Sample records for failure pressure evaluation

  1. Evaluation of Progressive Failure Analysis and Modeling of Impact Damage in Composite Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Sanchez, Christopher M.

    2011-01-01

    NASA White Sands Test Facility (WSTF) is leading an evaluation effort in advanced destructive and nondestructive testing of composite pressure vessels and structures. WSTF is using progressive finite element analysis methods for test design and for confirmation of composite pressure vessel performance. Using composite finite element analysis models and failure theories tested in the World-Wide Failure Exercise, WSTF is able to estimate the static strength of composite pressure vessels. Additionally, test and evaluation on composites that have been impact damaged is in progress so that models can be developed to estimate damage tolerance and the degradation in static strength.

  2. Levosimendan Prevents Pressure-Overload-induced Right Ventricular Failure.

    PubMed

    Hillgaard, Thomas Krarup; Andersen, Asger; Andersen, Stine; Vildbrad, Mads D; Ringgaard, Steffen; Nielsen, Jan M; Nielsen-Kudsk, Jens E

    2016-04-01

    We investigated if chronic levosimendan treatment can prevent and revert pressure-overload-induced right ventricular hypertrophy and failure in rats. Right ventricular hypertrophy and failure was induced in Wistar rats by pulmonary trunk banding (PTB). The PTB rats were treated with levosimendan (3 mg·kg·d) 3 days before surgery [n = 10, prevention (PREV)], 3 weeks after surgery [n = 10, reversal (REV)] or vehicle (n = 10, VEH). Sham-operated rats received vehicle (n = 16, SHAM). Right ventricular function was evaluated 7 weeks after surgery by echocardiography, magnetic resonance imaging, pressure-volume relations, gross anatomy, and histology. PTB induced right ventricular hypertrophy and compensated heart failure evident by reduced cardiac index (CI) without extra cardiac signs of heart failure. Levosimendan treatment prevented deterioration of right ventricular function measured by CI and right ventricular ejection fraction (RVEF) (CI: VEH vs. PREV 281 ± 17 vs. 362 ± 34 mL·min·kg, P ≤ 0.05, RVEF: VEH vs. PREV 57 ± 2% vs. 68 ± 3%, P ≤ 0.01) to values similar to SHAM (CI: 345 ± 21 mL·min·kg, RVEF: 71 ± 2%). RV contractility was improved in the REV group measured by preload recruitable stroke work (VEH vs. REV 39 ± 3 vs. 66 ± 10 mmHg P ≤ 0.05). Chronic treatment with levosimendan prevents the development of right ventricular failure and improves contractility in established pressure-overload-induced right ventricular failure.

  3. Prediction of failure pressure and leak rate of stress corrosion.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Majumdar, S.; Kasza, K.; Park, J. Y.

    2002-06-24

    An ''equivalent rectangular crack'' approach was employed to predict rupture pressures and leak rates through laboratory generated stress corrosion cracks and steam generator tubes removed from the McGuire Nuclear Station. Specimen flaws were sized by post-test fractography in addition to a pre-test advanced eddy current technique. The predicted and observed test data on rupture and leak rate are compared. In general, the test failure pressures and leak rates are closer to those predicted on the basis of fractography than on nondestructive evaluation (NDE). However, the predictions based on NDE results are encouraging, particularly because they have the potential to determinemore » a more detailed geometry of ligamented cracks, from which failure pressure and leak rate can be more accurately predicted. One test specimen displayed a time-dependent increase of leak rate under constant pressure.« less

  4. Esophageal and transpulmonary pressures in acute respiratory failure*

    PubMed Central

    Talmor, Daniel; Sarge, Todd; O’Donnell, Carl R.; Ritz, Ray; Malhotra, Atul; Lisbon, Alan; Loring, Stephen H.

    2008-01-01

    Objective Pressure inflating the lung during mechanical ventilation is the difference between pressure applied at the airway opening (Pao) and pleural pressure (Ppl). Depending on the chest wall’s contribution to respiratory mechanics, a given positive end-expiratory and/or end-inspiratory plateau pressure may be appropriate for one patient but inadequate or potentially injurious for another. Thus, failure to account for chest wall mechanics may affect results in clinical trials of mechanical ventilation strategies in acute respiratory distress syndrome. By measuring esophageal pressure (Pes), we sought to characterize influence of the chest wall on Ppl and transpulmonary pressure (PL) in patients with acute respiratory failure. Design Prospective observational study. Setting Medical and surgical intensive care units at Beth Israel Deaconess Medical Center. Patients Seventy patients with acute respiratory failure. Interventions: Placement of esophageal balloon-catheters. Measurements and Main Results Airway, esophageal, and gastric pressures recorded at end-exhalation and end-inflation Pes averaged 17.5 ± 5.7 cm H2O at end-expiration and 21.2 ± 7.7 cm H2O at end-inflation and were not significantly correlated with body mass index or chest wall elastance. Estimated PL was 1.5 ± 6.3 cm H2O at end-expiration, 21.4 ± 9.3 cm H2O at end-inflation, and 18.4 ± 10.2 cm H2O (n = 40) during an end-inspiratory hold (plateau). Although PL at end-expiration was significantly correlated with positive end-expiratory pressure (p < .0001), only 24% of the variance in PL was explained by Pao (R2 = .243), and 52% was due to variation in Pes. Conclusions In patients in acute respiratory failure, elevated esophageal pressures suggest that chest wall mechanical properties often contribute substantially and unpredictably to total respiratory impedance, and therefore Pao may not adequately predict PL or lung distention. Systematic use of esophageal manometry has the potential to

  5. Statistical Performance Evaluation Of Soft Seat Pressure Relief Valves

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Harris, Stephen P.; Gross, Robert E.

    2013-03-26

    Risk-based inspection methods enable estimation of the probability of failure on demand for spring-operated pressure relief valves at the United States Department of Energy's Savannah River Site in Aiken, South Carolina. This paper presents a statistical performance evaluation of soft seat spring operated pressure relief valves. These pressure relief valves are typically smaller and of lower cost than hard seat (metal to metal) pressure relief valves and can provide substantial cost savings in fluid service applications (air, gas, liquid, and steam) providing that probability of failure on demand (the probability that the pressure relief valve fails to perform its intendedmore » safety function during a potentially dangerous over pressurization) is at least as good as that for hard seat valves. The research in this paper shows that the proportion of soft seat spring operated pressure relief valves failing is the same or less than that of hard seat valves, and that for failed valves, soft seat valves typically have failure ratios of proof test pressure to set pressure less than that of hard seat valves.« less

  6. Round-robin analysis of the behavior of a 1:6-scale reinforced concrete containment model pressurized to failure: Posttest evaluations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Clauss, D.B.

    A 1:6-scale model of a reinforced concrete containment building was pressurized incrementally to failure at a remote site at Sandia National Laboratories. The response of the model was recorded with more than 1000 channels of data (primarily strain and displacement measurements) at 37 discrete pressure levels. The primary objective of this test was to generate data that could be used to validate methods for predicting the performance of containment buildings subject to loads beyond their design basis. Extensive analyses were conducted before the test to predict the behavior of the model. Ten organizations in Europe and the US conducted independentmore » analyses of the model and contributed to a report on the pretest predictions. Predictions included structural response at certain predetermined locations in the model as well as capacity and failure mode. This report discusses comparisons between the pretest predictions and the experimental results. Posttest evaluations that were conducted to provide additional insight into the model behavior are also described. The significance of the analysis and testing of the 1:6-scale model to performance evaluations of actual containments subject to beyond design basis loads is also discussed. 70 refs., 428 figs., 24 tabs.« less

  7. Evaluation of hawthorn extract on immunomodulatory biomarkers in a pressure overload model of heart failure.

    PubMed

    Bleske, Barry E; Zineh, Issam; Hwang, Hyun Seok; Welder, Gregory J; Ghannam, Michael M J; Boluyt, Marvin O

    2007-12-01

    Hawthorn extract (Crataegeus sp.) a botanical complementary and alternative medicine is often used to treat heart failure. The mechanism(s) by which hawthorn extract may treat heart failure is unknown but may include, theoretically, immunological effects. Therefore, the purpose of this study is to determine the effect of hawthorn extract on the immunomodulatory response in a pressure overload model of heart failure. A total of 62 male Sprague-Dawley rats were randomized to either aortic constriction + vehicle (AC; n=15), aortic constriction + hawthorn 1.3 mg/kg (HL, n=17), aortic constriction + hawthorn 13 mg/kg (HM, n=15), or aortic constriction + hawthorn 130 mg/kg (HH, n=15). Six months after surgical procedure animals were sacrificed and plasma samples obtained for the measurement of the following immunomodulatory markers: interleukin (IL) IL-1ss, IL-2, IL-6, IL-10; and leptin. The mortality rate following 6 months of aortic constriction was 40% in the AC group compared to 41%, 60%, and 53% for the HL, HM, and HH groups respectively (P>0.05 compared to AC). Aortic constriction produced a similar increase in the left ventricle/body weight ratio for all groups. Hawthorn extract had no effect on the immunomodulatory markers measured in this study, although there appeared to be a trend suggesting suppression of IL-2 plasma concentrations. In this animal model of heart failure, hawthorn extract failed to significantly affect the immunomodulatory response characterized after 6 months of pressure overload at a time when approximately 50% mortality was exhibited. Mechanisms other than immunological may better define hawthorn's effect in treating heart failure.

  8. Simplified failure sequence evaluation of reactor pressure vessel head corroding in-core instrumentation assembly

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McVicker, J.P.; Conner, J.T.; Hasrouni, P.N.

    1995-11-01

    In-Core Instrumentation (ICI) assemblies located on a Reactor Pressure Vessel Head have a history of boric acid leakage. The acid tends to corrode the nuts and studs which fasten the flanges of the assembly, thereby compromising the assembly`s structural integrity. This paper provides a simplified practical approach in determining the likelihood of an undetected progressing assembly stud deterioration, which would lead to a catastrophic loss of reactor coolant. The structural behavior of the In-Core Instrumentation flanged assembly is modeled using an elastic composite section assumption, with the studs transmitting tension and the pressure sealing gasket experiencing compression. Using the abovemore » technique, one can calculate the flange relative deflection and the consequential coolant loss flow rate, as well as the stress in any stud. A solved real life example develops the expected failure sequence and discusses the exigency of leak detection for safe shutdown. In the particular case of Calvert Cliffs Nuclear Power Plant (CCNPP) it is concluded that leak detection occurs before catastrophic failure of the ICI flange assembly.« less

  9. Relation between lowered colloid osmotic pressure, respiratory failure, and death.

    PubMed

    Tonnesen, A S; Gabel, J C; McLeavey, C A

    1977-01-01

    Plasma colloid osmotic pressure was measured each day in 84 intensive care unit patients. Probit analysis demonstrated a direct relationship between colloid osmotic pressure (COP) and survival. The COP associated with a 50% survival rate was 15.0 torr. COP was higher in survivors than in nonsurvivors without respiratory failure and in patients who recovered from respiratory failure. We conclude that lowered COP is associated with an elevated mortality rate. However, the relationship to death is not explained by the relationship to respiratory failure.

  10. Effects of Gas Pressure on the Failure Characteristics of Coal

    NASA Astrophysics Data System (ADS)

    Xie, Guangxiang; Yin, Zhiqiang; Wang, Lei; Hu, Zuxiang; Zhu, Chuanqi

    2017-07-01

    Several experiments were conducted using self-developed equipment for visual gas-solid coupling mechanics. The raw coal specimens were stored in a container filled with gas (99% CH4) under different initial gas pressure conditions (0.0, 0.5, 1.0, and 1.5 MPa) for 24 h prior to testing. Then, the specimens were tested in a rock-testing machine, and the mechanical properties, surface deformation and failure modes were recorded using strain gauges, an acoustic emission (AE) system and a camera. An analysis of the fractals of fragments and dissipated energy was performed to understand the changes observed in the stress-strain and crack propagation behaviour of the gas-containing coal specimens. The results demonstrate that increased gas pressure leads to a reduction in the uniaxial compression strength (UCS) of gas-containing coal and the critical dilatancy stress. The AE, surface deformation and fractal analysis results show that the failure mode changes during the gas state. Interestingly, a higher initial gas pressure will cause the damaged cracks and failure of the gas-containing coal samples to become severe. The dissipated energy characteristic in the failure process of a gas-containing coal sample is analysed using a combination of fractal theory and energy principles. Using the theory of fracture mechanics, based on theoretical analyses and calculations, the stress intensity factor of crack tips increases as the gas pressure increases, which is the main cause of the reduction in the UCS and critical dilatancy stress and explains the influence of gas in coal failure. More serious failure is created in gas-containing coal under a high gas pressure and low exterior load.

  11. Explosive Event in MON-3 Oxidizer System Resulting from Pressure Transducer Failure

    NASA Technical Reports Server (NTRS)

    Baker, David L.; Reynolds, Michael; Anderson, John

    2006-01-01

    In 2003, a Druck(Registered Trademark) pressure transducer failed catastrophically in a test system circulating nitrogen tetroxide at NASA Johnson Space Center White Sands Test Facility. The cause of the explosion was not immediately obvious since the wetted areas of the pressure transducer were constructed of materials compatible with nitrogen tetroxide. Chemical analysis of the resulting residue and a materials analysis of the diaphragm and its weld zones were used to determine the chain of events that led to the catastrophic failure. Due to excessive dynamic pressure loading in the test system, the diaphragm in the pressure transducer suffered cyclic failure and allowed the silicon oil located behind the isolation diaphragm to mix with the nitrogen tetroxide. The reaction between these two chemicals formed a combination of 2,4-di and 2,4,6-trinitrophenol, which are shock sensitive explosives that caused the failure of the pressure transducer. Further research indicated numerous manufacturers offer similar pressure transducers with silicone oil separated from the test fluid by a thin stainless steel isolation diaphragm. Caution must be exercised when purchasing a pressure transducer for a particular system to avoid costly failures and test system contamination.

  12. Mitochondrial division/mitophagy inhibitor (Mdivi) Ameliorates Pressure Overload Induced Heart Failure

    PubMed Central

    Givvimani, Srikanth; Munjal, Charu; Tyagi, Neetu; Sen, Utpal; Metreveli, Naira; Tyagi, Suresh C.

    2012-01-01

    Background We have previously reported the role of anti-angiogenic factors in inducing the transition from compensatory cardiac hypertrophy to heart failure and the significance of MMP-9 and TIMP-3 in promoting this process during pressure overload hemodynamic stress. Several studies reported the evidence of cardiac autophagy, involving removal of cellular organelles like mitochondria (mitophagy), peroxisomes etc., in the pathogenesis of heart failure. However, little is known regarding the therapeutic role of mitochondrial division inhibitor (Mdivi) in the pressure overload induced heart failure. We hypothesize that treatment with mitochondrial division inhibitor (Mdivi) inhibits abnormal mitophagy in a pressure overload heart and thus ameliorates heart failure condition. Materials and Methods To verify this, ascending aortic banding was done in wild type mice to create pressure overload induced heart failure and then treated with Mdivi and compared with vehicle treated controls. Results Expression of MMP-2, vascular endothelial growth factor, CD31, was increased, while expression of anti angiogenic factors like endostatin and angiostatin along with MMP-9, TIMP-3 was reduced in Mdivi treated AB 8 weeks mice compared to vehicle treated controls. Expression of mitophagy markers like LC3 and p62 was decreased in Mdivi treated mice compared to controls. Cardiac functional status assessed by echocardiography showed improvement and there is also a decrease in the deposition of fibrosis in Mdivi treated mice compared to controls. Conclusion Above results suggest that Mdivi inhibits the abnormal cardiac mitophagy response during sustained pressure overload stress and propose the novel therapeutic role of Mdivi in ameliorating heart failure. PMID:22479323

  13. Failure strength of the bovine caudal disc under internal hydrostatic pressure.

    PubMed

    Schechtman, Helio; Robertson, Peter A; Broom, Neil D

    2006-01-01

    The structure of the disc is both complex and inhomogeneous, and it functions as a successful load-bearing organ by virtue of the integration of its various structural regions. These same features also render it impossible to assess the failure strength of the disc from isolated tissue samples, which at best can only yield material properties. This study investigated the intrinsic failure strength of the intact bovine caudal disc under a simple mode of internal hydrostatic pressure. Using a hydraulic actuator, coloured hydrogel was injected under monitored pressure into the nucleus through a hollow screw insert which passed longitudinally through one of the attached vertebrae. Failure did not involve vertebra/endplate structures. Rather, failure of the disc annulus was indicated by the simultaneous manifestation of a sudden loss of gel pressure, a flood of gel colouration appearing in the outer annulus and audible fibrous tearing. A mean hydrostatic failure pressure of 18+/-3 MPa was observed which was approximated as a thick-wall hoop stress of 45+/-7 MPa. The experiment provides a measurement of the intrinsic strength of the disc using a method of internal hydrostatic loading which avoids any disruption of the complex architecture of the annular wall. Although the disc in vivo is subjected to a much more complex pattern of loading than is achieved using simple hydrostatic pressurization, this latter mode provides a useful tool for investigating alterations in intrinsic disc strength associated with prior loading history or degeneration.

  14. MitoQ improves mitochondrial dysfunction in heart failure induced by pressure overload.

    PubMed

    Ribeiro Junior, Rogério Faustino; Dabkowski, Erinne Rose; Shekar, Kadambari Chandra; O Connell, Kelly A; Hecker, Peter A; Murphy, Michael P

    2018-03-01

    Heart failure remains a major public-health problem with an increase in the number of patients worsening from this disease. Despite current medical therapy, the condition still has a poor prognosis. Heart failure is complex but mitochondrial dysfunction seems to be an important target to improve cardiac function directly. Our goal was to analyze the effects of MitoQ (100 µM in drinking water) on the development and progression of heart failure induced by pressure overload after 14 weeks. The main findings are that pressure overload-induced heart failure in rats decreased cardiac function in vivo that was not altered by MitoQ. However, we observed a reduction in right ventricular hypertrophy and lung congestion in heart failure animals treated with MitoQ. Heart failure also decreased total mitochondrial protein content, mitochondrial membrane potential in the intermyofibrillar mitochondria. MitoQ restored membrane potential in IFM but did not restore mitochondrial protein content. These alterations are associated with the impairment of basal and stimulated mitochondrial respiration in IFM and SSM induced by heart failure. Moreover, MitoQ restored mitochondrial respiration in heart failure induced by pressure overload. We also detected higher levels of hydrogen peroxide production in heart failure and MitoQ restored the increase in ROS production. MitoQ was also able to improve mitochondrial calcium retention capacity, mainly in the SSM whereas in the IFM we observed a small alteration. In summary, MitoQ improves mitochondrial dysfunction in heart failure induced by pressure overload, by decreasing hydrogen peroxide formation, improving mitochondrial respiration and improving mPTP opening. Published by Elsevier Inc.

  15. Outcomes and complications of intracranial pressure monitoring in acute liver failure: a retrospective cohort study.

    PubMed

    Karvellas, Constantine J; Fix, Oren K; Battenhouse, Holly; Durkalski, Valerie; Sanders, Corron; Lee, William M

    2014-05-01

    To determine if intracranial pressure monitor placement in patients with acute liver failure is associated with significant clinical outcomes. Retrospective multicenter cohort study. Academic liver transplant centers comprising the U.S. Acute Liver Failure Study Group. Adult critically ill patients with acute liver failure presenting with grade III/IV hepatic encephalopathy (n = 629) prospectively enrolled between March 2004 and August 2011. Intracranial pressure monitored (n = 140) versus nonmonitored controls (n = 489). Intracranial pressure monitored patients were younger than controls (35 vs 43 yr, p < 0.001) and more likely to be on renal replacement therapy (52% vs 38%, p = 0.003). Of 87 intracranial pressure monitored patients with detailed information, 44 (51%) had evidence of intracranial hypertension (intracranial pressure > 25 mm Hg) and overall 21-day mortality was higher in patients with intracranial hypertension (43% vs 23%, p = 0.05). During the first 7 days, intracranial pressure monitored patients received more intracranial hypertension-directed therapies (mannitol, 56% vs 21%; hypertonic saline, 14% vs 7%; hypothermia, 24% vs 10%; p < 0.03 for each). Forty-one percent of intracranial pressure monitored patients received liver transplant (vs 18% controls; p < 0.001). Overall 21-day mortality was similar (intracranial pressure monitored 33% vs controls 38%, p = 0.24). Where data were available, hemorrhagic complications were rare in intracranial pressure monitored patients (4 of 56 [7%]; three died). When stratifying by acetaminophen status and adjusting for confounders, intracranial pressure monitor placement did not impact 21-day mortality in acetaminophen patients (p = 0.89). However, intracranial pressure monitor was associated with increased 21-day mortality in nonacetaminophen patients (odds ratio, ~ 3.04; p = 0.014). In intracranial pressure monitored patients with acute liver failure, intracranial hypertension is commonly observed. The use

  16. Cost-Effectiveness of Implantable Pulmonary Artery Pressure Monitoring in Chronic Heart Failure.

    PubMed

    Sandhu, Alexander T; Goldhaber-Fiebert, Jeremy D; Owens, Douglas K; Turakhia, Mintu P; Kaiser, Daniel W; Heidenreich, Paul A

    2016-05-01

    This study aimed to evaluate the cost-effectiveness of the CardioMEMS (CardioMEMS Heart Failure System, St Jude Medical Inc, Atlanta, Georgia) device in patients with chronic heart failure. The CardioMEMS device, an implantable pulmonary artery pressure monitor, was shown to reduce hospitalizations for heart failure and improve quality of life in the CHAMPION (CardioMEMS Heart Sensor Allows Monitoring of Pressure to Improve Outcomes in NYHA Class III Heart Failure Patients) trial. We developed a Markov model to determine the hospitalization, survival, quality of life, cost, and incremental cost-effectiveness ratio of CardioMEMS implantation compared with usual care among a CHAMPION trial cohort of patients with heart failure. We obtained event rates and utilities from published trial data; we used costs from literature estimates and Medicare reimbursement data. We performed subgroup analyses of preserved and reduced ejection fraction and an exploratory analysis in a lower-risk cohort on the basis of the CHARM (Candesartan in Heart failure: Reduction in Mortality and Morbidity) trials. CardioMEMS reduced lifetime hospitalizations (2.18 vs. 3.12), increased quality-adjusted life-years (QALYs) (2.74 vs. 2.46), and increased costs ($176,648 vs. $156,569), thus yielding a cost of $71,462 per QALY gained and $48,054 per life-year gained. The cost per QALY gained was $82,301 in patients with reduced ejection fraction and $47,768 in those with preserved ejection fraction. In the lower-risk CHARM cohort, the device would need to reduce hospitalizations for heart failure by 41% to cost <$100,000 per QALY gained. The cost-effectiveness was most sensitive to the device's durability. In populations similar to that of the CHAMPION trial, the CardioMEMS device is cost-effective if the trial effectiveness is sustained over long periods. Post-marketing surveillance data on durability will further clarify its value. Copyright © 2016 American College of Cardiology Foundation

  17. [Mean values of blood pressure and endothelin plasma concentration in patients with chronic renal failure].

    PubMed

    Kocur, E; Kidawa, Z; Polakowski, P; Orszulak-Michalak, D; Karpinski, J; Rogulski, B; Wołkanin, P

    1998-09-01

    The aim of the present study was evaluation of correlation between big-endothelin concentration of the precursor substance of endothelin and mean values of blood pressure in 13 patients with compensates chronic renal failure. Their age ranged from 29 years to 55 years the mean age was 42.9 +/- 8.2 years. The patients were from the Consultational Nephrologic Outpatient Clinic. These patients were sent to the clinic after a hospital observation with recognised chronic renal failure (CRF), caused by chronic glomerulonephritis (without pathomorphological differentiation). The control group consistent of 10 healthy volunteers, an age ranged from 22 years to 49 years, a mean was 32.6 +/- 10.8 years. The following mean blood pressure values were found: in patient group a systolic pressure was 139.1 +/- 17.3 mm Hg and a diastolic pressure was 88.4 +/- 12.5 mm Hg and similar values in healthy control group were respectively: 118.6 +/- 4.0 and 72.4 +/- 5.9 mm Hg. Analogously the proendothelin concentration was 18.48 +/- 22.04 fmol/ml in patients with CRF and it was 4.67 +/- 0.27 fmol/ml in the control group. A positive correlation between mean blood systolic pressure values and the proendothelin concentration (r = 0.666, Y = 0.52X + 129.5; p < 0.05) in the was found patients group.

  18. Direct Left Atrial Pressure Monitoring in Severe Heart Failure: Long-Term Sensor Performance

    PubMed Central

    Ritzema, Jay; Eigler, Neal L.; Melton, Iain C.; Krum, Henry; Adamson, Philip B.; Kar, Saibal; Shah, Prediman K.; Whiting, James S.; Heywood, J. Thomas; Rosero, Spencer; Singh, Jagmeet P.; Saxon, Leslie; Matthews, Ray; Crozier, Ian G.; Abraham, William T.

    2010-01-01

    We report the stability, accuracy, and development history of a new left atrial pressure (LAP) sensing system in ambulatory heart failure (HF) patients. A total of 84 patients with advanced HF underwent percutaneous transseptal implantation of the pressure sensor. Quarterly noninvasive calibration by modified Valsalva maneuver was achieved in all patients, and 96.5% of calibration sessions were successful with a reproducibility of 1.2 mmHg. Absolute sensor drift was maximal after 3 months at 4.7 mmHg (95% CI, 3.2–6.2 mmHg) and remained stable through 48 months. LAP was highly correlated with simultaneous pulmonary wedge pressure at 3 and 12 months (r = 0.98, average difference of 0.8 ± 4.0 mmHg). Freedom from device failure was 95% (n = 37) at 2 years and 88% (n = 12) at 4 years. Causes of failure were identified and mitigated with 100% freedom from device failure and less severe anomalies in the last 41 consecutive patients (p = 0.005). Accurate and reliable LAP measurement using a chronic implanted monitoring system is safe and feasible in patients with advanced heart failure. PMID:20945124

  19. Impact of changes in blood pressure during the treatment of acute decompensated heart failure on renal and clinical outcomes.

    PubMed

    Testani, Jeffrey M; Coca, Steven G; McCauley, Brian D; Shannon, Richard P; Kimmel, Stephen E

    2011-08-01

    One of the primary determinants of blood flow in regional vascular beds is perfusion pressure. Our aim was to investigate if reduction in blood pressure during the treatment of decompensated heart failure would be associated with worsening renal function (WRF). Our secondary aim was to evaluate the prognostic significance of this potentially treatment-induced form of WRF. Subjects included in the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) trial limited data were studied (386 patients). Reduction in systolic blood pressure (SBP) was greater in patients experiencing WRF (-10.3 ± 18.5 vs. -2.8 ± 16.0 mmHg, P < 0.001) with larger reductions associated with greater odds for WRF (odds ratio = 1.3 per 10 mmHg reduction, P < 0.001). Systolic blood pressure reduction (relative change > median) was associated with greater doses of in-hospital oral vasodilators (P ≤ 0.017), thiazide diuretic use (P = 0.035), and greater weight reduction (P = 0.023). In patients with SBP-reduction, WRF was not associated with worsened survival [adjusted hazard ratio (HR) = 0.76, P = 0.58]. However, in patients without SBP-reduction, WRF was strongly associated with increased mortality (adjusted HR = 5.3, P < 0.001, P interaction = 0.001). During the treatment of decompensated heart failure, significant blood pressure reduction is strongly associated with WRF. However, WRF that occurs in the setting of SBP-reduction is not associated with an adverse prognosis, whereas WRF in the absence of this provocation is strongly associated with increased mortality. These data suggest that WRF may represent the final common pathway of several mechanistically distinct processes, each with potentially different prognostic implications.

  20. [Implantable sensors for outpatient assessment of ventricular filling pressure in advanced heart failure : Which telemonitoring design is optimal?

    PubMed

    Herrmann, E; Fichtlscherer, S; Hohnloser, S H; Zeiher, A M; Aßmus, B

    2016-12-01

    Patients with advanced heart failure suffer from frequent hospitalizations. Non-invasive hemodynamic telemonitoring for assessment of ventricular filling pressure has been shown to reduce hospitalizations. We report on the right ventricular (RVP), the pulmonary artery (PAP) and the left atrial pressure (LAP) sensor for non-invasive assessment of the ventricular filling pressure. A literature search concerning the available implantable pressure sensors for noninvasive haemodynamic telemonitoring in patients with advanced heart failure was performed. Until now, only implantation of the PAP-sensor was able to reduce hospitalizations for cardiac decompensation and to improve quality of life. The right ventricular pressure sensor missed the primary endpoint of a significant reduction of hospitalizations, clinical data using the left atrial pressure sensor are still pending. The implantation of a pressure sensor for assessment of pulmonary artery filling pressure is suitable for reducing hospitalizations for heart failure and for improving quality of life in patients with advanced heart failure.

  1. Impact of changes in blood pressure during the treatment of acute decompensated heart failure on renal and clinical outcomes†

    PubMed Central

    Testani, Jeffrey M.; Coca, Steven G.; McCauley, Brian D.; Shannon, Richard P.; Kimmel, Stephen E.

    2011-01-01

    Aims One of the primary determinants of blood flow in regional vascular beds is perfusion pressure. Our aim was to investigate if reduction in blood pressure during the treatment of decompensated heart failure would be associated with worsening renal function (WRF). Our secondary aim was to evaluate the prognostic significance of this potentially treatment-induced form of WRF. Methods and results Subjects included in the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) trial limited data were studied (386 patients). Reduction in systolic blood pressure (SBP) was greater in patients experiencing WRF (−10.3 ± 18.5 vs. −2.8 ± 16.0 mmHg, P < 0.001) with larger reductions associated with greater odds for WRF (odds ratio = 1.3 per 10 mmHg reduction, P < 0.001). Systolic blood pressure reduction (relative change > median) was associated with greater doses of in-hospital oral vasodilators (P ≤ 0.017), thiazide diuretic use (P = 0.035), and greater weight reduction (P = 0.023). In patients with SBP-reduction, WRF was not associated with worsened survival [adjusted hazard ratio (HR) = 0.76, P = 0.58]. However, in patients without SBP-reduction, WRF was strongly associated with increased mortality (adjusted HR = 5.3, P < 0.001, P interaction = 0.001). Conclusion During the treatment of decompensated heart failure, significant blood pressure reduction is strongly associated with WRF. However, WRF that occurs in the setting of SBP-reduction is not associated with an adverse prognosis, whereas WRF in the absence of this provocation is strongly associated with increased mortality. These data suggest that WRF may represent the final common pathway of several mechanistically distinct processes, each with potentially different prognostic implications. PMID:21693504

  2. Activation of PPAR-α in the early stage of heart failure maintained myocardial function and energetics in pressure-overload heart failure.

    PubMed

    Kaimoto, Satoshi; Hoshino, Atsushi; Ariyoshi, Makoto; Okawa, Yoshifumi; Tateishi, Shuhei; Ono, Kazunori; Uchihashi, Motoki; Fukai, Kuniyoshi; Iwai-Kanai, Eri; Matoba, Satoaki

    2017-02-01

    Failing heart loses its metabolic flexibility, relying increasingly on glucose as its preferential substrate and decreasing fatty acid oxidation (FAO). Peroxisome proliferator-activated receptor α (PPAR-α) is a key regulator of this substrate shift. However, its role during heart failure is complex and remains unclear. Recent studies reported that heart failure develops in the heart of myosin heavy chain-PPAR-α transgenic mice in a manner similar to that of diabetic cardiomyopathy, whereas cardiac dysfunction is enhanced in PPAR-α knockout mice in response to chronic pressure overload. We created a pressure-overload heart failure model in mice through transverse aortic constriction (TAC) and activated PPAR-α during heart failure using an inducible transgenic model. After 8 wk of TAC, left ventricular (LV) function had decreased with the reduction of PPAR-α expression in wild-type mice. We examined the effect of PPAR-α induction during heart failure using the Tet-Off system. Eight weeks after the TAC operation, LV construction was preserved significantly by PPAR-α induction with an increase in PPAR-α-targeted genes related to fatty acid metabolism. The increase of expression of fibrosis-related genes was significantly attenuated by PPAR-α induction. Metabolic rates measured by isolated heart perfusions showed a reduction in FAO and glucose oxidation in TAC hearts, but the rate of FAO preserved significantly owing to the induction of PPAR-α. Myocardial high-energy phosphates were significantly preserved by PPAR-α induction. These results suggest that PPAR-α activation during pressure-overloaded heart failure improved myocardial function and energetics. Thus activating PPAR-α and modulation of FAO could be a promising therapeutic strategy for heart failure. NEW & NOTEWORTHY The present study demonstrates the role of PPAR-α activation in the early stage of heart failure using an inducible transgenic mouse model. Induction of PPAR-α preserved heart

  3. Fractographic study of a thick wall pressure vessel failure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Canonico, D.A.; Crouse, R.S.; Henson, T.J.

    1979-01-01

    The pressure vessel described in this paper is identified as Intermediate Test Vessel 1 (ITV-1) and was fabricated of SA508, Class 2 Steel. It was tested to failure at 54/sup 0/C (130/sup 0/F). The gross failure appeared to be a brittle fracture although accompanied by a measured strain of 0.9%. Seven regions of the fracture were examined in detail and the observed surfaces were compared to Charpy V-notch (C/sub v/) specimens of SA508, Class 2 steel broken at temperatures above and below the ductile to brittle transition temperature. Three samples from the vessel were taken in the region around themore » fatigue notch and four from areas well removed from the notch. All these were carefully examined both optically and by scanning electron microscopy (SEM). It was established that early crack extension was by ductile mode until a large flaw approximately 500 mm long 83 mm wide was developed. At this point the vessel could no longer contain the internal pressure and final rupture was by brittle fracture.« less

  4. Failure analysis of thick composite cylinders under external pressure

    NASA Technical Reports Server (NTRS)

    Caiazzo, A.; Rosen, B. W.

    1992-01-01

    Failure of thick section composites due to local compression strength and overall structural instability is treated. Effects of material nonlinearity, imperfect fiber architecture, and structural imperfections upon anticipated failure stresses are determined. Comparisons with experimental data for a series of test cylinders are described. Predicting the failure strength of composite structures requires consideration of stability and material strength modes of failure using linear and nonlinear analysis techniques. Material strength prediction requires the accurate definition of the local multiaxial stress state in the material. An elasticity solution for the linear static analysis of thick anisotropic cylinders and rings is used herein to predict the axisymmetric stress state in the cylinders. Asymmetric nonlinear behavior due to initial cylinder out of roundness and the effects of end closure structure are treated using finite element methods. It is assumed that local fiber or ply waviness is an important factor in the initiation of material failure. An analytical model for the prediction of compression failure of fiber composites, which includes the effects of fiber misalignments, matrix inelasticity, and multiaxial applied stresses is used for material strength calculations. Analytical results are compared to experimental data for a series of glass and carbon fiber reinforced epoxy cylinders subjected to external pressure. Recommendations for pretest characterization and other experimental issues are presented. Implications for material and structural design are discussed.

  5. Negative-Pressure Ventilation in Pediatric Acute Respiratory Failure.

    PubMed

    Hassinger, Amanda B; Breuer, Ryan K; Nutty, Kirsten; Ma, Chang-Xing; Al Ibrahim, Omar S

    2017-12-01

    The objective of this work was to describe the use of negative-pressure ventilation (NPV) in a heterogeneous critically ill, pediatric population. A retrospective chart review was conducted of all patients admitted to a pediatric ICU with acute respiratory failure supported with NPV from January 1, 2012 to May 15, 2015. Two hundred thirty-three subjects at a median age of 15.5 months were supported with NPV for various etiologies, most commonly bronchiolitis (70%). Median (interquartile range) duration of support was 18.7 (8.7-34.3) h. The majority were NPV responders (70%), defined as not needing escalation to any form of positive-pressure ventilation. In non-responders, escalation occurred at a median (interquartile range) of 6.9 (3.3-16.6) h. More NPV non-responders had upper-airway obstruction ( P = .02), and fewer had bronchiolitis ( P = .008) compared with responders. A bedside scoring system developed on these data was 98% specific in predicting NPV failure by 4 h after NPV start (area under the curve 0.759, 95% CI 0.675-0.843, P < .001). Complications from NPV were rare (3%); however, delayed enteral nutrition (33%) and continuous intravenous sedation use (51%) in children while receiving NPV were more frequent. The annual percentage of pediatric ICU admissions requiring intubation declined by 28% in the 3 y after NPV introduction, compared with the 3 y prior. NPV is a noninvasive respiratory support for pediatric acute respiratory failure from all causes with few complications and a 70% response rate. Children receiving NPV often required intravenous sedation for comfort, and one third received delayed enteral nutrition. Those who required escalation from NPV worsened within 6 h; this may be predictable with a bedside scoring system. Copyright © 2017 by Daedalus Enterprises.

  6. A Study of Failure in Small Pressurized Cylindrical Shells Containing a Crack

    NASA Technical Reports Server (NTRS)

    Barwell, Craig A.; Eber, Lorenz; Fyfe, Ian M.

    1998-01-01

    The deformation in the vicinity of axial cracks in thin pressurized cylinders is examined using small experimental The deformation in the vicinity of axial cracks in thin pressurized cylinders is examined using small experimental models. The loading applied was either symmetric or unsymmetric about the crack plane, the latter being caused by structural constraints such as stringers. The objective was two fold - one, to provide the experimental results which will allow computer modeling techniques to be evaluated for deformations that are significantly different from that experienced by flat plates, and the other to examine the deformations and conditions associated with the onset of crack kinking which often precedes crack curving. The stresses which control crack growth in a cylindrical geometry depend on conditions introduced by the axial bulging, which is an integral part of this type of failure. For the symmetric geometry, both the hoop and radial strain just ahead off the crack, r = a, were measured and these results compared with those obtained from a variety of structural analysis codes, in particular STAGS [1], ABAQUS and ANSYS. In addition to these measurements, the pressures at the onset of stable and unstable crack growth were obtained and the corresponding crack deformations measured as the pressures were increased to failure. For the unsymmetric cases, measurements were taken of the crack kinking angle, and the displacements in the vicinity of the crack. In general, the strains ahead of the crack showed good agreement between the three computer codes and between the codes and the experiments. In the case of crack behavior, it was determined that modeling stable tearing with a crack-tip opening displacement fracture criterion could be successfully combined with the finite-element analysis techniques as used in structural analysis codes. The analytic results obtained in this study were very compatible with the experimental observations of crack growth

  7. Stress analysis and failure of an internally pressurized composite-jacketed steel cylinder

    NASA Technical Reports Server (NTRS)

    Chen, Peter C. T.

    1992-01-01

    This paper presents a nonlinear stress analysis of a thick-walled compound tube subjected to internal pressure. The compound tube is constructed of a steel liner and a graphite-bismaleimide outer shell. Analytical expressions for the stresses, strains, and displacements are derived for all loading ranges up to failure. Numerical results for the stresses and the maximum value that the compound tube can contain without failure are presented.

  8. Clinical monitoring of intracranial pressure in fulminant hepatic failure.

    PubMed

    Hanid, M A; Davies, M; Mellon, P J; Silk, D B; Strunin, L; McCabe, J J; Williams, R

    1980-10-01

    Cerebral oedema is the commonest immediate cause of death in fulminant hepatic failure and an investigation was carried out to determine the value of monitoring intracranial pressure (ICP) and to examine the effects of ICP of dexamethasone therapy and mannitol administration. ICP values in 10 patients at the time of insertion of a subdural pressure transducer (grade IV encephalopathy) averaged 15.5 +/- SD 14.8 mmHg. Despite dexamethansone therapy, which had been started on admission, rises in ICP were subsequently observed in seven of the eight patients who died. In the two patients who survived, the highest reading were 47 and 35 mmHg. Mannitol consistently reversed or arrested ICP rises when pressure was < 60 mmHg. ICP monitoring provides additional information in the managment of patients and is essential if mannitol therapy is to be used.

  9. Prediction of Composite Pressure Vessel Failure Location using Fiber Bragg Grating Sensors

    NASA Technical Reports Server (NTRS)

    Kreger, Steven T.; Taylor, F. Tad; Ortyl, Nicholas E.; Grant, Joseph

    2006-01-01

    Ten composite pressure vessels were instrumented with fiber Bragg grating sensors in order to assess the strain levels of the vessel under various loading conditions. This paper and presentation will discuss the testing methodology, the test results, compare the testing results to the analytical model, and present a possible methodology for predicting the failure location and strain level of composite pressure vessels.

  10. Failure and life cycle evaluation of watering valves.

    PubMed

    Gonzalez, David M; Graciano, Sandy J; Karlstad, John; Leblanc, Mathias; Clark, Tom; Holmes, Scott; Reuter, Jon D

    2011-09-01

    Automated watering systems provide a reliable source of ad libitum water to animal cages. Our facility uses an automated water delivery system to support approximately 95% of the housed population (approximately 14,000 mouse cages). Drinking valve failure rates from 2002 through 2006 never exceeded the manufacturer standard of 0.1% total failure, based on monthly cage census and the number of floods. In 2007, we noted an increase in both flooding and cases of clinical dehydration in our mouse population. Using manufacturer's specifications for a water flow rate of 25 to 50 mL/min, we initiated a wide-scale screening of all valves used. During a 4-mo period, approximately 17,000 valves were assessed, of which 2200 failed according to scoring criteria (12.9% overall; 7.2% low flow; 1.6% no flow; 4.1% leaky). Factors leading to valve failures included residual metal shavings, silicone flash, introduced debris or bedding, and (most common) distortion of the autoclave-rated internal diaphragm and O-ring. Further evaluation revealed that despite normal autoclave conditions of heat, pressure, and steam, an extreme negative vacuum pull caused the valves' internal silicone components (diaphragm and O-ring) to become distorted and water-permeable. Normal flow rate often returned after a 'drying out' period, but components then reabsorbed water while on the animal rack or during subsequent autoclave cycles to revert to a variable flow condition. On the basis of our findings, we recalibrated autoclaves and initiated a preventative maintenance program to mitigate the risk of future valve failure.

  11. Failure and Life Cycle Evaluation of Watering Valves

    PubMed Central

    Gonzalez, David M; Graciano, Sandy J; Karlstad, John; Leblanc, Mathias; Clark, Tom; Holmes, Scott; Reuter, Jon D

    2011-01-01

    Automated watering systems provide a reliable source of ad libitum water to animal cages. Our facility uses an automated water delivery system to support approximately 95% of the housed population (approximately 14,000 mouse cages). Drinking valve failure rates from 2002 through 2006 never exceeded the manufacturer standard of 0.1% total failure, based on monthly cage census and the number of floods. In 2007, we noted an increase in both flooding and cases of clinical dehydration in our mouse population. Using manufacturer's specifications for a water flow rate of 25 to 50 mL/min, we initiated a wide-scale screening of all valves used. During a 4-mo period, approximately 17,000 valves were assessed, of which 2200 failed according to scoring criteria (12.9% overall; 7.2% low flow; 1.6% no flow; 4.1% leaky). Factors leading to valve failures included residual metal shavings, silicone flash, introduced debris or bedding, and (most common) distortion of the autoclave-rated internal diaphragm and O-ring. Further evaluation revealed that despite normal autoclave conditions of heat, pressure, and steam, an extreme negative vacuum pull caused the valves’ internal silicone components (diaphragm and O-ring) to become distorted and water-permeable. Normal flow rate often returned after a ‘drying out’ period, but components then reabsorbed water while on the animal rack or during subsequent autoclave cycles to revert to a variable flow condition. On the basis of our findings, we recalibrated autoclaves and initiated a preventative maintenance program to mitigate the risk of future valve failure. PMID:22330720

  12. Filament-reinforced metal composite pressure vessel evaluation and performance demonstration

    NASA Technical Reports Server (NTRS)

    Landes, R. E.

    1976-01-01

    Two different Kevlar-49 filament-reinforced metal sphere designs were developed, and six vessels of each type were fabricated and subjected to fatigue cycling, sustained loading, and hydrostatic burst. The 61 cm (24 inch) diameter Kevlar-49/cryoformed 301 stainless steel pressure vessels demonstrated the required pressure cycle capability, burst factor of safety, and a maximum pressure times volume divided by weight (pV/W) performance of 210 J/g (834 000 in-lb/lbm) at burst; this represented a 25 to 30% weight saving over the lightest weight comparable, 6A1-4V Ti, homogeneous pressure vessel. Both the Kevlar/stainless steel design and the 97 cm (38 inch) diameter Kevlar-49/2219-T62 aluminum sphere design demonstrated nonfragmentation and controlled failure mode features when pressure cycled to failure at operating pressure. When failure occurred during pressure cycling, the mode was localized leakage and not catastrophic. Kevlar/stainless steel vessels utilized a unique conical boss design, and Kevlar/aluminum vessels incorporated a tie-rod to carry port loads; both styles of polar fittings performed as designed during operational testing of the vessels.

  13. Transcatheter Interatrial Shunt Device for the Treatment of Heart Failure: Rationale and Design of the Randomized Trial to REDUCE Elevated Left Atrial Pressure in Heart Failure (REDUCE LAP-HF I).

    PubMed

    Feldman, Ted; Komtebedde, Jan; Burkhoff, Daniel; Massaro, Joseph; Maurer, Mathew S; Leon, Martin B; Kaye, David; Silvestry, Frank E; Cleland, John G F; Kitzman, Dalane; Kubo, Spencer H; Van Veldhuisen, Dirk J; Kleber, Franz; Trochu, Jean-Noël; Auricchio, Angelo; Gustafsson, Finn; Hasenfuβ, Gerd; Ponikowski, Piotr; Filippatos, Gerasimos; Mauri, Laura; Shah, Sanjiv J

    2016-07-01

    Heart failure with preserved ejection fraction (HFpEF), a major public health problem with high morbidity and mortality rates, remains difficult to manage because of a lack of effective treatment options. Although HFpEF is a heterogeneous clinical syndrome, elevated left atrial pressure-either at rest or with exertion-is a common factor among all forms of HFpEF and one of the primary reasons for dyspnea and exercise intolerance in these patients. On the basis of clinical experience with congenital interatrial shunts in mitral stenosis, it has been hypothesized that the creation of a left-to-right interatrial shunt to decompress the left atrium (without compromising left ventricular filling or forward cardiac output) is a rational, nonpharmacological strategy for alleviating symptoms in patients with HFpEF. A novel transcatheter interatrial shunt device has been developed and evaluated in patients with HFpEF in single-arm, nonblinded clinical trials. These studies have demonstrated the safety and potential efficacy of the device. However, a randomized, placebo-controlled evaluation of the device is required to further evaluate its safety and efficacy in patients with HFpEF. In this article, we give the rationale for a therapeutic transcatheter interatrial shunt device in HFpEF, and we describe the design of REDUCE Elevated Left Atrial Pressure in Heart Failure (REDUCE LAP-HF I), the first randomized controlled trial of a device-based therapy to reduce left atrial pressure in HFpEF. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02600234. © 2016 American Heart Association, Inc.

  14. Safety and feasibility of pulmonary artery pressure-guided heart failure therapy: rationale and design of the prospective CardioMEMS Monitoring Study for Heart Failure (MEMS-HF).

    PubMed

    Angermann, Christiane E; Assmus, Birgit; Anker, Stefan D; Brachmann, Johannes; Ertl, Georg; Köhler, Friedrich; Rosenkranz, Stephan; Tschöpe, Carsten; Adamson, Philip B; Böhm, Michael

    2018-05-19

    Wireless monitoring of pulmonary artery (PA) pressures with the CardioMEMS HF™ system is indicated in patients with New York Heart Association (NYHA) class III heart failure (HF). Randomized and observational trials have shown a reduction in HF-related hospitalizations and improved quality of life in patients using this device in the United States. MEMS-HF is a prospective, non-randomized, open-label, multicenter study to characterize safety and feasibility of using remote PA pressure monitoring in a real-world setting in Germany, The Netherlands and Ireland. After informed consent, adult patients with NYHA class III HF and a recent HF-related hospitalization are evaluated for suitability for permanent implantation of a CardioMEMS™ sensor. Participation in MEMS-HF is open to qualifying subjects regardless of left ventricular ejection fraction (LVEF). Patients with reduced ejection fraction must be on stable guideline-directed pharmacotherapy as tolerated. The study will enroll 230 patients in approximately 35 centers. Expected duration is 36 months (24-month enrolment plus ≥ 12-month follow-up). Primary endpoints are freedom from device/system-related complications and freedom from pressure sensor failure at 12-month post-implant. Secondary endpoints include the annualized rate of HF-related hospitalization at 12 months versus the rate over the 12 months preceding implant, and health-related quality of life. Endpoints will be evaluated using data obtained after each subject's 12-month visit. The MEMS-HF study will provide robust evidence on the clinical safety and feasibility of implementing haemodynamic monitoring as a novel disease management tool in routine out-patient care in selected European healthcare systems. ClinicalTrials.gov; NCT02693691.

  15. Low-frequency blood pressure oscillations and inotrope treatment failure in premature infants.

    PubMed

    Vesoulis, Zachary A; Hao, Jessica; McPherson, Christopher; El Ters, Nathalie M; Mathur, Amit M

    2017-07-01

    The underlying mechanism as to why some hypotensive preterm infants do not respond to inotropic medications remains unclear. For these infants, we hypothesize that impaired vasomotor function is a significant factor and is manifested through a decrease in low-frequency blood pressure variability across regulatory components of vascular tone. Infants born ≤28 wk estimated gestational age underwent prospective recording of mean arterial blood pressure for 72 h after birth. After error correction, root-mean-square spectral power was calculated for each valid 10-min data frame across each of four frequency bands ( B1 , 0.005-0.0095 Hz; B2 , 0.0095-0.02 Hz; B3 , 0.02-0.06 Hz; and B4 , 0.06-0.16) corresponding to different components of vasomotion control. Forty infants (twenty-nine normotensive control and eleven inotrope-exposed) were included with a mean ± SD estimated gestational age of 25.2 ± 1.6 wk and birth weight 790 ± 211 g. 9.7/11.8 Million (82%) data points were error-free and used for analysis. Spectral power across all frequency bands increased with time, although the magnitude was 20% less in the inotrope-exposed infants. A statistically significant increase in spectral power in response to inotrope initiation was noted across all frequency bands. Infants with robust blood pressure response to inotropes had a greater increase compared with those who had limited or no blood pressure response. In this study, hypotensive infants who require inotropes have decreased low-frequency variability at baseline compared with normotensive infants, which increases after inotrope initiation. Low-frequency spectral power does not change for those with inotrope treatment failure, suggesting dysfunctional regulation of vascular tone as a potential mechanism of treatment failure. NEW & NOTEWORTHY In this study, we examine patterns of low-frequency oscillations in blood pressure variability across regulatory components of vascular tone in normotensive and

  16. Tendon–bone contact pressure and biomechanical evaluation of a modified suture-bridge technique for rotator cuff repair

    PubMed Central

    Geyer, Michael; Büschken, Meike; Buchhorn, Gottfried H.; Spahn, Gunter; Klinger, Hans-Michael

    2009-01-01

    The aim of the study was to evaluate the time-zero mechanical and footprint properties of a suture-bridge technique for rotator cuff repair in an animal model. Thirty fresh-frozen sheep shoulders were randomly assigned among three investigation groups: (1) cyclic loading, (2) load-to-failure testing, and (3) tendon–bone interface contact pressure measurement. Shoulders were cyclically loaded from 10 to 180 N and displacement to gap formation of 5- and 10-mm at the repair site. Cycles to failure were determined. Additionally, the ultimate tensile strength and stiffness were verified along with the mode of failure. The average contact pressure and pressure pattern were investigated using a pressure-sensitive film system. All of the specimens resisted against 3,000 cycles and none of them reached a gap formation of 10 mm. The number of cycles to 5-mm gap formation was 2,884.5 ± 96.8 cycles. The ultimate tensile strength was 565.8 ± 17.8 N and stiffness was 173.7 ± 9.9 N/mm. The entire specimen presented a unique mode of failure as it is well known in using high strength sutures by pulling them through the tendon. We observed a mean contact pressure of 1.19 ± 0.03 MPa, applied on the footprint area. The fundamental results of our study support the use of a suture-bridge technique for optimising the conditions of the healing biology of a reconstructed rotator cuff tendon. Nevertheless, an individual estimation has to be done if using the suture-bridge technique clinically. Further investigation is necessary to evaluate the cell biological healing process in order to achieve further sufficient advancements in rotator cuff repair. PMID:19826786

  17. Echocardiographic evaluation of right ventricular stroke work index in advanced heart failure: a new index?

    PubMed

    Frea, Simone; Bovolo, Virginia; Bergerone, Serena; D'Ascenzo, Fabrizio; Antolini, Marina; Capriolo, Michele; Canavosio, Federico Giovanni; Morello, Mara; Gaita, Fiorenzo

    2012-12-01

    Right ventricular (RV) function plays a pivotal role in advanced heart failure patients, especially for screening those who may benefit from left ventricular assist device (LVAD) implantation. We introduce RV contraction pressure index (RVCPI) as a new echo-Doppler parameter of RV function. The accuracy of RVCPI in detecting RV failure was compared with the criterion standard, the RV stroke work index (RVSWI) obtained through right heart catheterization in advanced heart failure patients referred for heart transplantation or LVAD implantation. Right heart catheterization and echo-Doppler were simultaneously performed in 94 consecutive patients referred to our center for advanced heart failure (ejection fraction (EF) 24 ± 8.8%, 40% NYHA functional class IV). RV stroke volume and invasive pulmonary pressures were used to obtain RVSWI. Simplified RVCPI (sRVCPI) was derived as TAPSE × (RV - right atrial pressure gradient). Close positive correlation between sRVCPI and RVSWI was found (r = 0.68; P < .001). With logistic regression, we found that increased sRVCPI showed an independent reduced risk (odds ratio 0.98, 95% confidence interval [CI] 0.97-0.99; P = .016) for patients to present a depressed RVSWI (<0.25 mm Hg/L·m(2)). Simplified RVCPI showed high diagnostic accuracy (area under the receiver operating characteristic curve 0.94, 95% CI 0.89-0.99) and good sensitivity and specificity (92% and 85%, respectively) to predict depressed RVSWI with the use of a cutoff value of <400 mm·mm Hg. In patients with advanced heart failure, the new simple bedside sRVCPI closely correlated with RVSWI, providing an independent, noninvasive, and easy tool for the evaluation of RV function. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Heart failure and the discrepancy between trials of intensive blood pressure management: an analysis of individual patient data.

    PubMed

    Aggarwal, Rahul; Mirzan, Haares; Chiu, Nicholas; Steinkamp, Jackson

    2018-02-26

    ACCORD and SPRINT are the best randomized controlled trial data evaluating the effects of blood pressure targets below 140 mmHg. These trials had contradictory results regarding the benefits of intensive antihypertensive therapy. We investigate if this discordance was driven by SPRINT's inclusion of Heart Failure in its primary outcome, as this is a parameter not included in ACCORD's original primary outcome. This analysis helps to resolve a significant area of contention. Individual patient data from 4733 participants in ACCORD were analyzed from time of randomization. All participants were diabetic and at increased cardiovascular risk. Participants were assigned to their original intervention, a standard blood pressure target of less than 140 mmHg or an intensive target of less than 120 mmHg. Primary composite outcome was defined as in SPRINT: a composite of first occurrence of myocardial infarction, stroke, heart failure, death from cardiovascular causes, and other acute coronary syndromes. Primary outcome was not significantly different between standard and intensive groups [HR: 0.89; 95% CI: (0.76-1.03); p = 0.108]. The primary composite outcome occurred in 370 participants in the standard group (15.6%) and 324 participants in the intensive group (13.7%), with an event rate of 3.38% per year for the standard group and 3.01% per year for the intensive group. Differing results between ACCORD and SPRINT are not attributable to ACCORD's exclusion of Heart Failure from its original primary outcome measurement. No significant differences in primary outcome were observed between intensive and standard blood pressure groups in the ACCORD patients under the SPRINT primary outcome definition. Caution should be taken in extrapolating the intensive blood pressure control benefits of SPRINT to the diabetic population.

  19. Factors Associated with Failure of Non-invasive Positive Pressure Ventilation in a Critical Care Helicopter Emergency Medical Service.

    PubMed

    Lee, James S; O'Dochartaigh, Domhnall; MacKenzie, Mark; Hudson, Darren; Couperthwaite, Stephanie; Villa-Roel, Cristina; Rowe, Brian H

    2015-06-01

    Non-invasive positive pressure ventilation (NIPPV) is used to treat severe acute respiratory distress. Prehospital NIPPV has been associated with a reduction in both in-hospital mortality and the need for invasive ventilation. The authors of this study examined factors associated with NIPPV failure and evaluated the impact of NIPPV on scene times in a critical care helicopter Emergency Medical Service (HEMS). Non-invasive positive pressure ventilation failure was defined as the need for airway intervention or alternative means of ventilatory support. A retrospective chart review of consecutive patients where NIPPV was completed in a critical care HEMS was conducted. Factors associated with NIPPV failure in univariate analyses and from published literature were included in a multivariable, logistic regression model. From a total of 44 patients, NIPPV failed in 14 (32%); a Glasgow Coma Scale (GCS)<15 at HEMS arrival was associated independently with NIPPV failure (adjusted odds ratio 13.9; 95% CI, 2.4-80.3; P=.003). Mean scene times were significantly longer in patients who failed NIPPV when compared with patients in whom NIPPV was successful (95 minutes vs 51 minutes; 39.4 minutes longer; 95% CI, 16.2-62.5; P=.001). Patients with a decreased level of consciousness were more likely to fail NIPPV. Furthermore, patients who failed NIPPV had significantly longer scene times. The benefits of NIPPV should be balanced against risks of long scene times by HEMS providers. Knowing risk factors of NIPPV failure could assist HEMS providers to make the safest decision for patients on whether to initiate NIPPV or proceed directly to endotracheal intubation prior to transport.

  20. Failure Pressure and Leak Rate of Steam Generator Tubes With Stress Corrosion Cracks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Majumdar, S.; Kasza, K.; Park, J.Y.

    2002-07-01

    This paper illustrates the use of an 'equivalent rectangular crack' approach to predict leak rates through laboratory generated stress corrosion cracks. A comparison between predicted and observed test data on rupture and leak rate from laboratory generated stress corrosion cracks are provided. Specimen flaws were sized by post-test fractography in addition to pre-test advanced eddy current technique. The test failure pressures and leak rates are shown to be closer to those predicted on the basis of fractography than on NDE. However, the predictions based on NDE results are encouraging, particularly because they have the potential to determine a more detailedmore » geometry of ligamentous cracks from which more accurate predictions of failure pressure and leak rate can be made in the future. (authors)« less

  1. Mitochondrial proteome remodelling in pressure overload-induced heart failure: the role of mitochondrial oxidative stress

    PubMed Central

    Dai, Dao-Fu; Hsieh, Edward J.; Liu, Yonggang; Chen, Tony; Beyer, Richard P.; Chin, Michael T.; MacCoss, Michael J.; Rabinovitch, Peter S.

    2012-01-01

    Aims We investigate the role of mitochondrial oxidative stress in mitochondrial proteome remodelling using mouse models of heart failure induced by pressure overload. Methods and results We demonstrate that mice overexpressing catalase targeted to mitochondria (mCAT) attenuate pressure overload-induced heart failure. An improved method of label-free unbiased analysis of the mitochondrial proteome was applied to the mouse model of heart failure induced by transverse aortic constriction (TAC). A total of 425 mitochondrial proteins were compared between wild-type and mCAT mice receiving TAC or sham surgery. The changes in the mitochondrial proteome in heart failure included decreased abundance of proteins involved in fatty acid metabolism, an increased abundance of proteins in glycolysis, apoptosis, mitochondrial unfolded protein response and proteolysis, transcription and translational control, and developmental processes as well as responses to stimuli. Overexpression of mCAT better preserved proteins involved in fatty acid metabolism and attenuated the increases in apoptotic and proteolytic enzymes. Interestingly, gene ontology analysis also showed that monosaccharide metabolic processes and protein folding/proteolysis were only overrepresented in mCAT but not in wild-type mice in response to TAC. Conclusion This is the first study to demonstrate that scavenging mitochondrial reactive oxygen species (ROS) by mCAT not only attenuates most of the mitochondrial proteome changes in heart failure, but also induces a subset of unique alterations. These changes represent processes that are adaptive to the increased work and metabolic requirements of pressure overload, but which are normally inhibited by overproduction of mitochondrial ROS. PMID:22012956

  2. BPC 157 therapy to detriment sphincters failure-esophagitis-pancreatitis in rat and acute pancreatitis patients low sphincters pressure.

    PubMed

    Petrovic, I; Dobric, I; Drmic, D; Sever, M; Klicek, R; Radic, B; Brcic, L; Kolenc, D; Zlatar, M; Kunjko, K; Jurcic, D; Martinac, M; Rasic, Z; Boban Blagaic, A; Romic, Z; Seiwerth, S; Sikiric, P

    2011-10-01

    Possibly, acute esophagitis and pancreatitis cause each other, and we focused on sphincteric failure as the common causative key able to induce either esophagitis and acute pancreatitis or both of them, and thereby investigate the presence of a common therapy nominator. This may be an anti-ulcer pentadecapeptide BPC 157 (tested for inflammatory bowel disease, wound treatment) affecting esophagitis, lower esophageal and pyloric sphincters failure and acute pancreatitis (10 μg/kg, 10 ng/kg intraperitoneally or in drinking water). The esophagitis-sphincter failure procedure (i.e., insertion of the tubes into the sphincters, lower esophageal and pyloric) and acute pancreatitis procedure (i.e., bile duct ligation) were combined in rats. Esophageal manometry was done in acute pancreatitis patients. In rats acute pancreatitis procedure produced also esophagitis and both sphincter failure, decreased pressure 24 h post-surgery. Furthermore, bile duct ligation alone immediately declines the pressure in both sphincters. Vice versa, the esophagitis-sphincter failure procedure alone produced acute pancreatitis. What's more, these lesions (esophagitis, sphincter failure, acute pancreatitis when combined) aggravate each other (tubes into sphincters and ligated bile duct). Counteraction occurred by BPC 157 therapies. In acute pancreatitis patients lower pressure at rest was in both esophageal sphincters in acute pancreatitis patients. We conclude that BPC 157 could cure esophagitis/sphincter/acute pancreatitis healing failure.

  3. Lay Consultations in Heart Failure Symptom Evaluation.

    PubMed

    Reeder, Katherine M; Sims, Jessica L; Ercole, Patrick M; Shetty, Shivan S; Wallendorf, Michael

    2017-01-01

    Lay consultations can facilitate or impede healthcare. However, little is known about how lay consultations for symptom evaluation affect treatment decision-making. The purpose of this study was to explore the role of lay consultations in symptom evaluation prior to hospitalization among patients with heart failure. Semi-structured interviews were conducted with 60 patients hospitalized for acute decompensated heart failure. Chi-square and Fisher's exact tests, along with logistic regression were used to characterize lay consultations in this sample. A large proportion of patients engaged in lay consultations for symptom evaluation and decision-making before hospitalization. Lay consultants provided attributions and advice and helped make the decision to seek medical care. Men consulted more often with their spouse than women, while women more often consulted with adult children. Findings have implications for optimizing heart failure self-management interventions, improving outcomes, and reducing hospital readmissions.

  4. Lay Consultations in Heart Failure Symptom Evaluation

    PubMed Central

    Reeder, Katherine M.; Sims, Jessica L.; Ercole, Patrick M.; Shetty, Shivan S.; Wallendorf, Michael

    2017-01-01

    Purpose Lay consultations can facilitate or impede healthcare. However, little is known about how lay consultations for symptom evaluation affect treatment decision-making. The purpose of this study was to explore the role of lay consultations in symptom evaluation prior to hospitalization among patients with heart failure. Methods Semi-structured interviews were conducted with 60 patients hospitalized for acute decompensated heart failure. Chi-square and Fisher’s exact tests, along with logistic regression were used to characterize lay consultations in this sample. Results A large proportion of patients engaged in lay consultations for symptom evaluation and decision-making before hospitalization. Lay consultants provided attributions and advice and helped make the decision to seek medical care. Men consulted more often with their spouse than women, while women more often consulted with adult children. Conclusions Findings have implications for optimizing heart failure self-management interventions, improving outcomes, and reducing hospital readmissions. PMID:29399657

  5. Differing prognostic value of pulse pressure in patients with heart failure with reduced or preserved ejection fraction: results from the MAGGIC individual patient meta-analysis.

    PubMed

    Jackson, Colette E; Castagno, Davide; Maggioni, Aldo P; Køber, Lars; Squire, Iain B; Swedberg, Karl; Andersson, Bert; Richards, A Mark; Bayes-Genis, Antoni; Tribouilloy, Christophe; Dobson, Joanna; Ariti, Cono A; Poppe, Katrina K; Earle, Nikki; Whalley, Gillian; Pocock, Stuart J; Doughty, Robert N; McMurray, John J V

    2015-05-07

    Low pulse pressure is a marker of adverse outcome in patients with heart failure (HF) and reduced ejection fraction (HF-REF) but the prognostic value of pulse pressure in patients with HF and preserved ejection fraction (HF-PEF) is unknown. We examined the prognostic value of pulse pressure in patients with HF-PEF [ejection fraction (EF) ≥ 50%] and HF-REF. Data from 22 HF studies were examined. Preserved left ventricular ejection fraction (LVEF) was defined as LVEF ≥ 50%. All-cause mortality at 3 years was evaluated in 27 046 patients: 22 038 with HF-REF (4980 deaths) and 5008 with HF-PEF (828 deaths). Pulse pressure was analysed in quintiles in a multivariable model adjusted for the previously reported Meta-Analysis Global Group in Chronic Heart Failure prognostic variables. Heart failure and reduced ejection fraction patients in the lowest pulse pressure quintile had the highest crude and adjusted mortality risk (adjusted hazard ratio 1.68, 95% confidence interval 1.53-1.84) compared with all other pulse pressure groups. For patients with HF-PEF, higher pulse pressure was associated with the highest crude mortality, a gradient that was eliminated after adjustment for other prognostic variables. Lower pulse pressure (especially <53 mmHg) was an independent predictor of mortality in patients with HF-REF, particularly in those with an LVEF < 30% and systolic blood pressure <140 mmHg. Overall, this relationship between pulse pressure and outcome was not consistently observed among patients with HF-PEF. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  6. Reliability Evaluation of Machine Center Components Based on Cascading Failure Analysis

    NASA Astrophysics Data System (ADS)

    Zhang, Ying-Zhi; Liu, Jin-Tong; Shen, Gui-Xiang; Long, Zhe; Sun, Shu-Guang

    2017-07-01

    In order to rectify the problems that the component reliability model exhibits deviation, and the evaluation result is low due to the overlook of failure propagation in traditional reliability evaluation of machine center components, a new reliability evaluation method based on cascading failure analysis and the failure influenced degree assessment is proposed. A direct graph model of cascading failure among components is established according to cascading failure mechanism analysis and graph theory. The failure influenced degrees of the system components are assessed by the adjacency matrix and its transposition, combined with the Pagerank algorithm. Based on the comprehensive failure probability function and total probability formula, the inherent failure probability function is determined to realize the reliability evaluation of the system components. Finally, the method is applied to a machine center, it shows the following: 1) The reliability evaluation values of the proposed method are at least 2.5% higher than those of the traditional method; 2) The difference between the comprehensive and inherent reliability of the system component presents a positive correlation with the failure influenced degree of the system component, which provides a theoretical basis for reliability allocation of machine center system.

  7. Noninvasive estimation of left atrial pressure in patients with congestive heart failure and mitral regurgitation by Doppler echocardiography.

    PubMed

    Gorcsan, J; Snow, F R; Paulsen, W; Nixon, J V

    1991-03-01

    A completely noninvasive method for estimating left atrial pressure in patients with congestive heart failure and mitral regurgitation has been devised with the use of continuous-wave Doppler echocardiography and brachial sphygmomanometry. Of 46 patients studied with mitral regurgitation, 35 (76%) had jets with distinct Doppler spectral envelopes recorded. The peak ventriculoatrial gradient was obtained by measuring peak mitral regurgitant velocity in systole and using the modified Bernoulli equation. This gradient was then subtracted from peak brachial systolic blood pressure, an estimate of left ventricular systolic pressure, to yield left atrial pressure (left atrial pressure = systolic blood pressure - mitral regurgitant pressure gradient). Noninvasive estimates of left atrial pressure from 35 patients were plotted against simultaneous recordings of mean pulmonary capillary wedge pressure resulting in the correlation y = 0.88x + 3.3, r = 0.88, standard error of estimate = +/- 4 mm Hg (p less than 0.001). Therefore, continuous-wave Doppler echocardiography and sphygmomanometry may be used in selected patients with congestive heart failure and mitral regurgitation for noninvasive estimation of left atrial pressure.

  8. Failure Behavior of Granite Affected by Confinement and Water Pressure and Its Influence on the Seepage Behavior by Laboratory Experiments

    PubMed Central

    Cheng, Cheng; Li, Xiao; Li, Shouding; Zheng, Bo

    2017-01-01

    Failure behavior of granite material is paramount for host rock stability of geological repositories for high-level waste (HLW) disposal. Failure behavior also affects the seepage behavior related to transportation of radionuclide. Few of the published studies gave a consistent analysis on how confinement and water pressure affect the failure behavior, which in turn influences the seepage behavior of the rock during the damage process. Based on a series of laboratory experiments on NRG01 granite samples cored from Alxa area, a candidate area for China’s HLW disposal, this paper presents some detailed observations and analyses for a better understanding on the failure mechanism and seepage behavior of the samples under different confinements and water pressure. The main findings of this study are as follows: (1) Strength reduction properties were found for the granite under water pressure. Besides, the complete axial stress–strain curves show more obvious yielding process in the pre-peak region and a more gradual stress drop in the post-peak region; (2) Shear fracturing pattern is more likely to form in the granite samples with the effect of water pressure, even under much lower confinements, than the predictions from the conventional triaxial compressive results; (3) Four stages of inflow rate curves are divided and the seepage behaviors are found to depend on the failure behavior affected by the confinement and water pressure. PMID:28773157

  9. Failure Behavior of Granite Affected by Confinement and Water Pressure and Its Influence on the Seepage Behavior by Laboratory Experiments.

    PubMed

    Cheng, Cheng; Li, Xiao; Li, Shouding; Zheng, Bo

    2017-07-14

    Failure behavior of granite material is paramount for host rock stability of geological repositories for high-level waste (HLW) disposal. Failure behavior also affects the seepage behavior related to transportation of radionuclide. Few of the published studies gave a consistent analysis on how confinement and water pressure affect the failure behavior, which in turn influences the seepage behavior of the rock during the damage process. Based on a series of laboratory experiments on NRG01 granite samples cored from Alxa area, a candidate area for China's HLW disposal, this paper presents some detailed observations and analyses for a better understanding on the failure mechanism and seepage behavior of the samples under different confinements and water pressure. The main findings of this study are as follows: (1) Strength reduction properties were found for the granite under water pressure. Besides, the complete axial stress-strain curves show more obvious yielding process in the pre-peak region and a more gradual stress drop in the post-peak region; (2) Shear fracturing pattern is more likely to form in the granite samples with the effect of water pressure, even under much lower confinements, than the predictions from the conventional triaxial compressive results; (3) Four stages of inflow rate curves are divided and the seepage behaviors are found to depend on the failure behavior affected by the confinement and water pressure.

  10. Blood pressure dynamics during exercise rehabilitation in heart failure patients.

    PubMed

    Hecht, Idan; Arad, Michael; Freimark, Dov; Klempfner, Robert

    2017-05-01

    Background Patients suffering from heart failure (HF) may demonstrate an abnormal blood pressure response to exercise (ABPRE), which may revert to a normal one following medical treatment. It is assumed that this change correlates positively with prognosis and functional aspects. The aim of this study was to characterize patients with ABPRE and assess ABPRE normalization and the correlation with clinical and functional outcomes. Methods In the study, 651 patients with HF who underwent cardiac rehabilitation (CR) were examined. Patients who presented an ABPRE during stress testing were identified and divided into those who corrected their initial ABPRE following CR and those who did not. Results Pre-rehabilitation ABPRE was present in 27% of patients, 68% of whom normalized their ABPRE following CR. Two parameters were independently predictive of failure to normalize the blood pressure response: female gender (odds ratio (OR) 3.5; 95% confidence interval (CI) 1.4-9.0) and decreased systolic function (OR 3.2; 95% CI 1.0-9.4). Patients with hypertrophic cardiomyopathy demonstrated higher rates of ABPRE normalization than patients with other causes of HF (93% vs. 62%, respectively, P = 0.03). The research population exhibited an average improvement in exercise capacity (4.7 to 6.4 metabolic equivalents (METS), P < .001), ejection fraction (35.4% to 37.7%, P < .001) and percentage of patients with New York Heart Association (NYHA) class 3-4 (50% to 43.4%, P = .123). The group who normalized their ABPRE exhibited greater improvement. Conclusions Amongst a population of patients suffering from HF, an ABPRE was normalized following CR in two thirds of patients. Female gender and a reduced systolic function independently predicted the failure to correct the ABPRE, while patients with hypertrophic cardiomyopathy demonstrated exceptionally high rates of normalization.

  11. Thin-metal lined PRD 49-III composite vessels. [evaluation of pressure vessels for burst strength and fatigue performance

    NASA Technical Reports Server (NTRS)

    Hoggatt, J. T.

    1974-01-01

    Filament wound pressure vessels of various configurations were evaluated for burst strength and fatigue performance. The dimensions and characteristics of the vessels are described. The types of tests conducted are explained. It was determined that all vessels leaked in a relatively few cycles (20 to 60 cycles) with failure occurring in all cases in the metallic liner. The thin liner would de-bond from the composite and buckling took place during depressurization. No composite failures or indications of impeding composite failures were obtained in the metal-lined vessels.

  12. Pressurized thermal shock evaluation of the Calvert Cliffs Unit 1 Nuclear Power Plant

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Abbott, L

    1985-09-01

    An evaluation of the risk to the Calvert Cliffs Unit 1 nuclear power plant due to pressurized thermal shock (PTS) has been completed by Oak Ridge National Laboratory (ORNL) with the assistance of several other organizations. This evaluation was part of a Nuclear Regulatory Commission program designed to study the PTS risk to three nuclear plants, the other two plants being Oconee Unit 1 and H.B. Robinson Unit 2. The specific objectives of the program were to (1) provide a best estimate of the frequency of a through-the-wall crack in the pressure vessel at each of the three plants, togethermore » with the uncertainty in the estimated frequency and its sensitivity to the variables used in the evaluation; (2) determine the dominant overcooling sequences contributing to the estimated frequency and the associated failures in the plant systems or in operator actions; and (3) evaluate the effectiveness of potential corrective measures.« less

  13. Drp1-Dependent Mitochondrial Autophagy Plays a Protective Role Against Pressure Overload-Induced Mitochondrial Dysfunction and Heart Failure.

    PubMed

    Shirakabe, Akihiro; Zhai, Peiyong; Ikeda, Yoshiyuki; Saito, Toshiro; Maejima, Yasuhiro; Hsu, Chiao-Po; Nomura, Masatoshi; Egashira, Kensuke; Levine, Beth; Sadoshima, Junichi

    2016-03-29

    Mitochondrial autophagy is an important mediator of mitochondrial quality control in cardiomyocytes. The occurrence of mitochondrial autophagy and its significance during cardiac hypertrophy are not well understood. Mice were subjected to transverse aortic constriction (TAC) and observed at multiple time points up to 30 days. Cardiac hypertrophy developed after 5 days, the ejection fraction was reduced after 14 days, and heart failure was observed 30 days after TAC. General autophagy was upregulated between 1 and 12 hours after TAC but was downregulated below physiological levels 5 days after TAC. Mitochondrial autophagy, evaluated by electron microscopy, mitochondrial content, and Keima with mitochondrial localization signal, was transiently activated at ≈3 to 7 days post-TAC, coinciding with mitochondrial translocation of Drp1. However, it was downregulated thereafter, followed by mitochondrial dysfunction. Haploinsufficiency of Drp1 abolished mitochondrial autophagy and exacerbated the development of both mitochondrial dysfunction and heart failure after TAC. Injection of Tat-Beclin 1, a potent inducer of autophagy, but not control peptide, on day 7 after TAC, partially rescued mitochondrial autophagy and attenuated mitochondrial dysfunction and heart failure induced by overload. Haploinsufficiency of either drp1 or beclin 1 prevented the rescue by Tat-Beclin 1, suggesting that its effect is mediated in part through autophagy, including mitochondrial autophagy. Mitochondrial autophagy is transiently activated and then downregulated in the mouse heart in response to pressure overload. Downregulation of mitochondrial autophagy plays an important role in mediating the development of mitochondrial dysfunction and heart failure, whereas restoration of mitochondrial autophagy attenuates dysfunction in the heart during pressure overload. © 2016 American Heart Association, Inc.

  14. [In vitro evaluation of the method effectiveness to limit inflation pressure cuffs of endotracheal tubes].

    PubMed

    Coelho, Rafael de Macedo; Paiva, Thiago Trigueiro Morais de; Mathias, Ligia Andrade da Silva Telles

    2016-01-01

    Cuffs of tracheal tubes protect the lower airway from aspiration of gastric contents and facilitate ventilation, but may cause many complications, especially when the cuff pressure exceeds 30cm H2O. This occurs in over 30% of conventional insufflations, so it is recommended to limit this pressure. In this study we evaluated the in vitro effectiveness of a method of limiting the cuff pressure to a range between 20 and 30cm H2O. Using an adapter to connect the tested tube to the anesthesia machine, the relief valve was regulated to 30cm H2O, inflating the cuff by operating the rapid flow of oxygen button. There were 33 trials for each tube of three manufacturers, of five sizes (6.5 to 8.5), using three times inflation (10, 15 and 20seconds), totaling 1485 tests. After inflation, the pressure obtained was measured with a manometer. Pressure >30cm H2O or <20cm H2O were considered failures. There were eight failures (0.5%, 95% CI: 0.1-0.9%), with all by pressures <20cm H2O and after 10seconds inflation (1.6%, 95% CI: 0 5-2.7%). One failure occurred with a 6.5 tube (0.3%, 95% CI: -0.3-0.9%), six with 7.0 tubes (2%, 95% CI: 0.4 to 3.6%), and one with a 7.5 tube (0.3%, 95% CI: -0.3-0.9%). This method was effective for inflating tracheal tube cuffs of different sizes and manufacturers, limiting its pressure to a range between 20 and 30cm H2O, with a success rate of 99.5% (95% CI: 99.1-99.9%). Copyright © 2014 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

  15. In vitro evaluation of the method effectiveness to limit inflation pressure cuffs of endotracheal tubes.

    PubMed

    Coelho, Rafael de Macedo; de Paiva, Thiago Trigueiro Morais; da Silva Telles Mathias, Ligia Andrade

    2016-01-01

    Cuffs of tracheal tubes protect the lower airway from aspiration of gastric contents and facilitate ventilation, but may cause many complications, especially when the cuff pressure exceeds 30cm H2O. This occurs in over 30% of conventional insufflations, so it is recommended to limit this pressure. In this study we evaluated the in vitro effectiveness of a method of limiting the cuff pressure to a range between 20 and 30cm H2O. Using an adapter to connect the tested tube to the anesthesia machine, the relief valve was regulated to 30cm H2O, inflating the cuff by operating the rapid flow of oxygen button. There were 33 trials for each tube of three manufacturers, of five sizes (6.5-8.5), using three times inflation (10, 15 and 20s), totaling 1485 tests. After inflation, the pressure obtained was measured with a manometer. Pressure >30cm H2O or <20cm H2O were considered failures. There were eight failures (0.5%, 95% CI: 0.1-0.9%), with all by pressures <20cm H2O and after 10s inflation (1.6%, 95% CI: 0 5-2.7%). One failure occurred with a 6.5 tube (0.3%, 95% CI: -0.3 to 0.9%), six with 7.0 tubes (2%, 95% CI: 0.4-3.6%), and one with a 7.5 tube (0.3%, 95% CI: -0.3 to 0.9%). This method was effective for inflating tracheal tube cuffs of different sizes and manufacturers, limiting its pressure to a range between 20 and 30cm H2O, with a success rate of 99.5% (95% CI: 99.1-99.9%). Copyright © 2014 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

  16. Heart Failure

    MedlinePlus

    ... cause heart failure, such as coronary artery disease, high blood pressure, diabetes or obesity. Symptoms Heart failure can be ongoing ( ... include: Not smoking Controlling certain conditions, such as high blood pressure and diabetes Staying physically active Eating healthy foods Maintaining a ...

  17. Relationship of right- to left-sided ventricular filling pressures in advanced heart failure: insights from the ESCAPE trial.

    PubMed

    Drazner, Mark H; Velez-Martinez, Mariella; Ayers, Colby R; Reimold, Sharon C; Thibodeau, Jennifer T; Mishkin, Joseph D; Mammen, Pradeep P A; Markham, David W; Patel, Chetan B

    2013-03-01

    Although right atrial pressure (RAP) and pulmonary capillary wedge pressure (PCWP) are correlated in heart failure, in a sizeable minority of patients, the RAP and PCWP are not tightly coupled. The basis of this variability in the RAP/PCWP ratio, and whether it conveys prognostic value, is not known. We analyzed the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) trial database. Baseline characteristics, including echocardiographic assessment of right ventricular (RV) structure and function, and invasively measured hemodynamic parameters, were compared among tertiles of the RAP/PCWP ratio. Multivariable Cox proportional hazard models assessed the association of RAP/PCWP ratio with the primary ESCAPE outcome (6-month death or hospitalization [days]) adjusting for systolic blood pressure, blood urea nitrogen, 6-minute walk distance, and PCWP. The RAP/PCWP tertiles were 0.27 to 0.4 (tertile 1); 0.41 to 0.615 (tertile 2), and 0.62 to 1.21 (tertile 3). Increasing RAP/PCWP was associated with increasing median right atrial area (23, 26, 29 cm2, respectively; P<0.005), RV area in diastole (21, 27, 27 cm2, respectively; P<0.005), and pulmonary vascular resistance (2.4, 2.9, 3.6 woods units, respectively; P=0.003), and lower RV stroke work index (8.6, 8.4, 5.5 g·m/m2 per beat, respectively; P<0.001). RAP/PCWP ratio was associated with death or hospitalization within 6 months (hazard ratio, 1.16 [1, 1.4]; P<0.05). Increased RAP/PCWP ratio was associated with higher pulmonary vascular resistance, reduced RV function (manifest as a larger right atrium and ventricle and lower RV stroke work index), and an increased risk of adverse outcomes in patients with advanced heart failure.

  18. Low diastolic blood pressure and adverse outcomes in heart failure with preserved ejection fraction.

    PubMed

    Tsujimoto, Tetsuro; Kajio, Hiroshi

    2018-07-15

    It remains unknown whether a low diastolic blood pressure (DBP) increases the risks of cardiovascular events and death in patients with heart failure with preserved ejection fraction (HFpEF). We used data from the TOPCAT trial. The primary outcome was a composite of all-cause death, non-fatal myocardial infarction, non-fatal stroke, or hospitalization for heart failure. Hazard ratios (HRs) were analyzed for DBPs of <60, 60-69, 70-79, and ≥90 mm Hg in comparison with a DBP of 80-89 mm Hg using multivariable Cox proportional hazard models. This study included 3417 patients with HFpEF who had a controlled blood pressure. In the mean follow-up period of 3.0 years, 881 patients experienced at least one confirmed primary outcome event. Compared with patients with a DBP of 80-89 mm Hg, the adjusted HRs for primary outcome events were significantly higher in those with DBPs of <60 mm Hg (HR: 2.19 [95% confidence interval,1.72-2.78]) and 60-69 mm Hg (HR: 1.52 [1.23-1.87]). Similarly, the adjusted HRs for all-cause death, major cardiovascular events, and hospitalization for heart failure, but not stroke, were significantly higher in patients with a DBP of <70 mm Hg. A relationship between a low DBP and adverse outcomes was found in HFpEF patients with a systolic blood pressure of ≥120 mm Hg; however, a low systolic blood pressure with a DBP of ≥70 mm Hg was not associated with these event risks. A low DBP increased the risks of adverse outcomes in patients with HFpEF. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  19. Right ventricular failure resulting from pressure overload: role of intra-aortic balloon counterpulsation and vasopressor therapy.

    PubMed

    Liakopoulos, Oliver J; Ho, Jonathan K; Yezbick, Aaron B; Sanchez, Elizabeth; Singh, Vivek; Mahajan, Aman

    2010-11-01

    Augmentation of coronary perfusion may improve right ventricular (RV) failure following acute increases of RV afterload. We investigated whether intra-aortic balloon counterpulsation (IABP) can improve cardiac function by enhancing myocardial perfusion and reversing compromised biventricular interactions using a model of acute pressure overload. In 10 anesthetized pigs, RV failure was induced by pulmonary artery constriction and systemic hypertension strategies with IABP, phenylephrine (PE), or the combination of both were tested. Systemic and ventricular hemodynamics [cardiac index(CI), ventricular pressures, coronary driving pressures (CDP)] were measured and echocardiography was used to assess tricuspid valve regurgitation, septal positioning (eccentricity index (ECI)), and changes in ventricular and septal dimensions and function [myocardial performance index (MPI), peak longitudinal strain]. Pulmonary artery constriction resulted in doubling of RV systolic pressure (54 ± 4mm Hg), RV distension, severe TR (4+) with decreased RV function (strain: -33%; MPI: +56%), septal flattening (Wt%: -35%) and leftward septal shift (ECI:1.36), resulting in global hemodynamic deterioration (CI: -51%; SvO(2): -26%), and impaired CDP (-30%; P<0.05). IABP support alone failed to improve RV function despite higher CDP (+33%; P<0.05). Systemic hypertension by PE improved CDP (+70%), RV function (strain: +22%; MPI: -21%), septal positioning (ECI:1.12) and minimized TR, but LV dysfunction (strain: -25%; MPI: +31%) occurred after LV afterloading (P<0.05). With IABP, less PE (-41%) was needed to maintain hypertension and CDP was further augmented (+25%). IABP resulted in LV unloading and restored LV function, and increased CI (+46%) and SvO(2) (+29%; P<0.05). IABP with minimal vasopressors augments myocardial perfusion pressure and optimizes RV function after pressure-induced failure. Copyright © 2010 Elsevier Inc. All rights reserved.

  20. Creep failure of a reactor pressure vessel lower head under severe accident conditions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pilch, M.M.; Ludwigsen, J.S.; Chu, T.Y.

    A severe accident in a nuclear power plant could result in the relocation of large quantities of molten core material onto the lower head of he reactor pressure vessel (RPV). In the absence of inherent cooling mechanisms, failure of the RPV ultimately becomes possible under the combined effects of system pressure and the thermal heat-up of the lower head. Sandia National Laboratories has performed seven experiments at 1:5th scale simulating creep failure of a RPV lower head. This paper describes a modeling program that complements the experimental program. Analyses have been performed using the general-purpose finite-element code ABAQUS-5.6. In ordermore » to make ABAQUS solve the specific problem at hand, a material constitutive model that utilizes temperature dependent properties has been developed and attached to ABAQUS-executable through its UMAT utility. Analyses of the LHF-1 experiment predict instability-type failure. Predicted strains are delayed relative to the observed strain histories. Parametric variations on either the yield stress, creep rate, or both (within the range of material property data) can bring predictions into agreement with experiment. The analysis indicates that it is necessary to conduct material property tests on the actual material used in the experimental program. The constitutive model employed in the present analyses is the subject of a separate publication.« less

  1. Evaluation of a Linear Cumulative Damage Failure Model for Epoxy Adhesive

    NASA Technical Reports Server (NTRS)

    Richardson, David E.; Batista-Rodriquez, Alicia; Macon, David; Totman, Peter; McCool, Alex (Technical Monitor)

    2001-01-01

    Recently a significant amount of work has been conducted to provide more complex and accurate material models for use in the evaluation of adhesive bondlines. Some of this has been prompted by recent studies into the effects of residual stresses on the integrity of bondlines. Several techniques have been developed for the analysis of bondline residual stresses. Key to these analyses is the criterion that is used for predicting failure. Residual stress loading of an adhesive bondline can occur over the life of the component. For many bonded systems, this can be several years. It is impractical to directly characterize failure of adhesive bondlines under a constant load for several years. Therefore, alternative approaches for predictions of bondline failures are required. In the past, cumulative damage failure models have been developed. These models have ranged from very simple to very complex. This paper documents the generation and evaluation of some of the most simple linear damage accumulation tensile failure models for an epoxy adhesive. This paper shows how several variations on the failure model were generated and presents an evaluation of the accuracy of these failure models in predicting creep failure of the adhesive. The paper shows that a simple failure model can be generated from short-term failure data for accurate predictions of long-term adhesive performance.

  2. Effect of Combined Loading Due to Bending and Internal Pressure on Pipe Flaw Evaluation Criteria

    NASA Astrophysics Data System (ADS)

    Miura, Naoki; Sakai, Shinsuke

    Considering a rule for the rationalization of maintenance of Light Water Reactor piping, reliable flaw evaluation criteria are essential for determining how a detected flaw will be detrimental to continuous plant operation. Ductile fracture is one of the dominant failure modes that must be considered for carbon steel piping and can be analyzed by elastic-plastic fracture mechanics. Some analytical efforts have provided various flaw evaluation criteria using load correction factors, such as the Z-factors in the JSME codes on fitness-for-service for nuclear power plants and the section XI of the ASME boiler and pressure vessel code. The present Z-factors were conventionally determined, taking conservativity and simplicity into account; however, the effect of internal pressure, which is an important factor under actual plant conditions, was not adequately considered. Recently, a J-estimation scheme, LBB.ENGC for the ductile fracture analysis of circumferentially through-wall-cracked pipes subjected to combined loading was developed for more accurate prediction under more realistic conditions. This method explicitly incorporates the contributions of both bending and tension due to internal pressure by means of a scheme that is compatible with an arbitrary combined-loading history. In this study, the effect of internal pressure on the flaw evaluation criteria was investigated using the new J-estimation scheme. The Z-factor obtained in this study was compared with the presently used Z-factors, and the predictability of the current flaw evaluation criteria was quantitatively evaluated in consideration of the internal pressure.

  3. Evaluation Methodologies for Estimating the Likelihood of Program Implementation Failure

    ERIC Educational Resources Information Center

    Durand, Roger; Decker, Phillip J.; Kirkman, Dorothy M.

    2014-01-01

    Despite our best efforts as evaluators, program implementation failures abound. A wide variety of valuable methodologies have been adopted to explain and evaluate the "why" of these failures. Yet, typically these methodologies have been employed concurrently (e.g., project monitoring) or to the post-hoc assessment of program activities.…

  4. Evaluation of strength and failure of brittle rock containing initial cracks under lithospheric conditions

    NASA Astrophysics Data System (ADS)

    Li, Xiaozhao; Qi, Chengzhi; Shao, Zhushan; Ma, Chao

    2018-02-01

    Natural brittle rock contains numerous randomly distributed microcracks. Crack initiation, growth, and coalescence play a predominant role in evaluation for the strength and failure of brittle rocks. A new analytical method is proposed to predict the strength and failure of brittle rocks containing initial microcracks. The formulation of this method is based on an improved wing crack model and a suggested micro-macro relation. In this improved wing crack model, the parameter of crack angle is especially introduced as a variable, and the analytical stress-crack relation considering crack angle effect is obtained. Coupling the proposed stress-crack relation and the suggested micro-macro relation describing the relation between crack growth and axial strain, the stress-strain constitutive relation is obtained to predict the rock strength and failure. Considering different initial microcrack sizes, friction coefficients and confining pressures, effects of crack angle on tensile wedge force acting on initial crack interface are studied, and effects of crack angle on stress-strain constitutive relation of rocks are also analyzed. The strength and crack initiation stress under different crack angles are discussed, and the value of most disadvantaged angle triggering crack initiation and rock failure is founded. The analytical results are similar to the published study results. Rationality of this proposed analytical method is verified.

  5. Acetylcysteine reduces plasma homocysteine concentration and improves pulse pressure and endothelial function in patients with end-stage renal failure.

    PubMed

    Scholze, Alexandra; Rinder, Christiane; Beige, Joachim; Riezler, Reiner; Zidek, Walter; Tepel, Martin

    2004-01-27

    Increased oxidative stress, elevated plasma homocysteine concentration, increased pulse pressure, and impaired endothelial function constitute risk factors for increased mortality in patients with end-stage renal failure. We investigated the metabolic and hemodynamic effects of intravenous administration of acetylcysteine, a thiol-containing antioxidant, during a hemodialysis session in a prospective, randomized, placebo-controlled crossover study in 20 patients with end-stage renal failure. Under control conditions, a hemodialysis session reduced plasma homocysteine concentration to 58+/-22% predialysis (mean+/-SD), whereas in the presence of acetylcysteine, the plasma homocysteine concentration was significantly more reduced to 12+/-7% predialysis (P<0.01). The reduction of plasma homocysteine concentration was significantly correlated with a reduction of pulse pressure. A 10% decrease in plasma homocysteine concentration was associated with a decrease of pulse pressure by 2.5 mm Hg. Analysis of the second derivative of photoplethysmogram waveform showed changes of arterial wave reflectance during hemodialysis in the presence of acetylcysteine, indicating improved endothelial function. Acetylcysteine-dependent increase of homocysteine removal during a hemodialysis session improves plasma homocysteine concentration, pulse pressure, and endothelial function in patients with end-stage renal failure.

  6. Midterm prospective evaluation of TVT-Secur reveals high failure rate.

    PubMed

    Cornu, Jean-Nicolas; Sèbe, Philippe; Peyrat, Laurence; Ciofu, Calin; Cussenot, Olivier; Haab, Francois

    2010-07-01

    TVT-Secur has been described as a new minimally invasive sling for women's stress urinary incontinence (SUI) management, showing promising results in short-term studies. Our goal was to evaluate the outcome of this procedure after a midterm follow-up. A prospective evaluation involved 45 consecutive patients presenting SUI associated with urethral hypermobility. Fourteen patients preoperatively reported overactive bladder (OAB) symptoms, but none had objective detrusor overactivity. Eight patients had low maximal urethral closure pressure (MUCP). Four patients had pelvic organ prolapse (POP). Patients with POP were treated under general anesthesia by Prolift and TVT-Secur procedure. The 41 other patients received TVT-Secur under local anesthesia on an outpatient basis. All interventions were made by the same surgeon. Postoperative assessment included pad count, bladder diary, clinical examination with stress test, evaluation of satisfaction with the Patient Global Impression of Improvement (PGI-I) scale, and evaluation of side effects. Patients were classified as cured if they used no pads, had no leakage, and had a PGI-I score < or = 2; as improved in case of reduction of SUI symptoms >50% and PGI-I score < or = 3; and as failure otherwise. Mean postoperative follow-up was 30.2 +/- 9.8 mo (range: 11-40 mo). Short-term evaluation showed a 93.5% success rate, but, at last follow-up, only 18 (40%) patients were cured, while 8 (18%) were improved, and 19 (42%) failed. Twelve patients underwent implantation of TVT or transobturator tape during follow-up. Age, MUCP, or OAB were not associated with failure. Side effects were limited to five cases of de novo OAB and three cases of urinary tract infection. This work is limited by the absence of a comparison group. Our experience shows that despite its good short-term efficacy, TVT-Secur is associated with a high recurrence rate of SUI. Therefore, TVT-Secur does not seem appropriate for SUI first-line management in women

  7. Positive pressure ventilation in the management of acute and chronic cardiac failure: a systematic review and meta-analysis.

    PubMed

    Nadar, Sunil; Prasad, Neeraj; Taylor, Rod S; Lip, Gregory Y H

    2005-03-18

    Chronic heart failure (CHF) is a common condition and is associated with excess morbidity and mortality, in spite of the many advances in its treatment. Chronic stable heart failure is also associated with an increased incidence of sleep-related breathing disorders, such as central sleep apnoea (CSA) and Cheyne Stokes respiration (CSR). Continuous positive airways pressure (CPAP) has been shown to alleviate the symptoms of CHF, improve left ventricular function and oxygenation. To a certain extent, CPAP also abolishes sleep-related breathing disorders in patients with chronic heart failure. In patients with acute pulmonary oedema, the use of positive pressure ventilation improves cardiac haemodynamic indices, as well as symptoms and oxygenation, and is associated with a lower need for intubation. However, some studies have cast doubts about its safety and suggest a higher rate of myocardial infarction associated with its use. In our opinion, non-invasive positive pressure ventilation and CPAP offers an adjunctive mode of therapy in patients with acute pulmonary oedema and chronic heart failure, who may not be suitable for intubation and in those not responsive to conventional therapies. Non-invasive ventilation also helps to improve oxygenation in those patients with exhaustion and respiratory acidosis. Many trials are still ongoing and the results of these studies would throw more light on the present role of non-invasive ventilation in the management of CHF.

  8. Factors Associated With Treatment Failure of Infected Pressure Sores.

    PubMed

    Jugun, Kheeldass; Richard, Jean-Christophe; Lipsky, Benjamin A; Kressmann, Benjamin; Pittet-Cuenod, Brigitte; Suvà, Domizio; Modarressi, Ali; Uçkay, Ilker

    2016-08-01

    In this study, we assess interdisciplinary surgical and medical parameters associated to recurrences of infected pressure ulcers. There is a little in the published literature regarding factors associated with the outcome of treatment of infected pressure ulcers. We undertook a single-center review of spinal injured adults hospitalized for an infected pressure ulcer or implant-free osteomyelitis and reviewed the literature on this topic from 1990-2015. We found 70 lesions in 31 patients (52 with osteomyelitis) who had a median follow-up of 2.7 years (range, 4 months to 19 years). The median duration of antibiotic therapy was 6 weeks, of which 1 week was parenteral. Clinical recurrence after treatment was noted in 44 infected ulcers (63%), after a median interval of 1 year. In 86% of these recurrences, cultures yielded a different organism than the preceding episode. By multivariate analyses, the following factors were not significantly related to recurrence: number of surgical interventions (hazard ratio 0.9, 95% confidence interval 0.5-1.5); osteomyelitis (hazard ratio 1.5; 0.7-3.1); immune suppression; prior sacral infections, and duration of total (or just parenteral) antibiotic sue. Patients with antibiotic treatment for <6 weeks had the same failure rate as those with as >12 weeks (χ test; P = 0.90). In patients with infected pressure ulcers, clinical recurrence occurs in almost two-thirds of lesions, but in only 14% with the same pathogen(s). The number of surgical debridements, flap use, or duration of antibiotic therapy was not associated with recurrence, suggesting recurrences are caused by reinfections caused by other extrahospital factors.

  9. Mononuclear Phagocytes Are Dispensable for Cardiac Remodeling in Established Pressure-Overload Heart Failure

    PubMed Central

    Patel, Bindiya; Ismahil, Mohamed Ameen; Hamid, Tariq; Bansal, Shyam S.; Prabhu, Sumanth D.

    2017-01-01

    Background Although cardiac and splenic mononuclear phagocytes (MPs), i.e., monocytes, macrophages and dendritic cells (DCs), are key contributors to cardiac remodeling after myocardial infarction, their role in pressure-overload remodeling is unclear. We tested the hypothesis that these immune cells are required for the progression of remodeling in pressure-overload heart failure (HF), and that MP depletion would ameliorate remodeling. Methods and Results C57BL/6 mice were subjected to transverse aortic constriction (TAC) or sham operation, and assessed for alterations in MPs. As compared with sham, TAC mice exhibited expansion of circulating LyC6hi monocytes and pro-inflammatory CD206− cardiac macrophages early (1 w) after pressure-overload, prior to significant hypertrophy and systolic dysfunction, with subsequent resolution during chronic HF. In contrast, classical DCs were expanded in the heart in a biphasic manner, with peaks both early, analogous to macrophages, and late (8 w), during established HF. There was no significant expansion of circulating DCs, or Ly6C+ monocytes and DCs in the spleen. Periodic systemic MP depletion from 2 to 16 w after TAC in macrophage Fas-induced apoptosis (MaFIA) transgenic mice did not alter cardiac remodeling progression, nor did splenectomy in mice with established HF after TAC. Lastly, adoptive transfer of splenocytes from TAC HF mice into naïve recipients did not induce immediate or long-term cardiac dysfunction in recipient mice. Conclusions Mononuclear phagocytes populations expand in a phasic manner in the heart during pressure-overload. However, they are dispensable for the progression of remodeling and failure once significant hypertrophy is evident and blood monocytosis has normalized. PMID:28125666

  10. Causes of corneal graft failure in India.

    PubMed

    Dandona, L; Naduvilath, T J; Janarthanan, M; Rao, G N

    1998-09-01

    The success of corneal grafting in visual rehabilitation of the corneal blind in India depends on survival of the grafts. Understanding the causes of graft failure may help reduce the risk of failure. We studied these causes in a series of 638 graft failures at our institution. Multivariate logistic regression analysis was used to evaluate the association of particular causes of graft failure with indications for grafting, socioeconomic status, age, sex, host corneal vascularization, donor corneal quality, and experience of surgeon. The major causes of graft failure were allograft rejection (29.2%), increased intraocular pressure (16.9%), infection excluding endophthalmitis (15.4%), and surface problems (12.7%). The odds of infection causing graft failure were significantly higher in patients of lower socioeconomic status (odds ratio 2.45, 95% CI 1.45-4.15). Surface problems as a cause of graft failure was significantly associated with grafts done for corneal scarring or for regrafts (odds ratio 3.36, 95% CI 1.80-6.30). Increased intraocular pressure as a cause of graft failure had significant association with grafts done for aphakic or pseudophakic bullous keratopathy, congenital conditions or glaucoma, or regrafts (odds ratio 2.19, 95% CI 1.25-3.84). Corneal dystrophy was the indication for grafting in 12 of the 13 cases of graft failure due to recurrence of host disease. Surface problems, increased intraocular pressure, and infection are modifiable risk factors that are more likely to cause graft failure in certain categories of patients in India. Knowledge about these associations can be helpful in looking for and aggressively treating these modifiable risk factors in the at-risk categories of corneal graft patients. This can possibly reduce the chance of graft failure.

  11. Dynamic analysis method for prevention of failure in the first-stage low-pressure turbine blade with two-finger root

    NASA Astrophysics Data System (ADS)

    Park, Jung-Yong; Jung, Yong-Keun; Park, Jong-Jin; Kang, Yong-Ho

    2002-05-01

    Failures of turbine blades are identified as the leading causes of unplanned outages for steam turbine. Accidents of low-pressure turbine blade occupied more than 70 percent in turbine components. Therefore, the prevention of failures for low pressure turbine blades is certainly needed. The procedure is illustrated by the case study. This procedure is used to guide, and support the plant manager's decisions to avoid a costly, unplanned outage. In this study, we are trying to find factors of failures in LP turbine blade and to make three steps to approach the solution of blade failure. First step is to measure natural frequency in mockup test and to compare it with nozzle passing frequency. Second step is to use FEM and to calculate the natural frequencies of 7 blades and 10 blades per group in BLADE code. Third step is to find natural frequencies of grouped blade off the nozzle passing frequency.

  12. Liquefaction, flow, and associated ground failure

    USGS Publications Warehouse

    Youd, T. Leslie

    1973-01-01

    Ambiguities in the use of the term liquefaction and in defining the relation between liquefaction and ground failure have led to encumbered communication between workers in various fields and between specialists in the same field, and the possibility that evaluations of liquefaction potential could be misinterpreted or misapplied. Explicit definitions of liquefaction and related concepts are proposed herein. These definitions, based on observed laboratory behavior, are then used to clarify the relation between liquefaction and ground failure. Soil liquefaction is defined as the transformation of a granular material from a solid into a liquefied state as a consequence of increased pore-water pressures. This definition avoids confusion between liquefaction and possible flow-failure conditions after liquefaction. Flow-failure conditions are divided into two types: (1) unlimited flow if pore-pressure reductions caused by dilatancy during flow deformation are not sufficient to solidify the material and thus arrest flow, and (2) limited flow if they are sufficient to solidify the material after a finite deformation. After liquefaction in the field, unlimited flow commonly leads to flow landslides, whereas limited flow leads at most to lateral-spreading landslides. Quick-condition failures such as loss of bearing capacity form a third type of ground failure associated with liquefaction.

  13. On-line detection of key radionuclides for fuel-rod failure in a pressurized water reactor.

    PubMed

    Qin, Guoxiu; Chen, Xilin; Guo, Xiaoqing; Ni, Ning

    2016-08-01

    For early on-line detection of fuel rod failure, the key radionuclides useful in monitoring must leak easily from failing rods. Yield, half-life, and mass share of fission products that enter the primary coolant also need to be considered in on-line analyses. From all the nuclides that enter the primary coolant during fuel-rod failure, (135)Xe and (88)Kr were ultimately chosen as crucial for on-line monitoring of fuel-rod failure. A monitoring system for fuel-rod failure detection for pressurized water reactor (PWR) based on the LaBr3(Ce) detector was assembled and tested. The samples of coolant from the PWR were measured using the system as well as a HPGe γ-ray spectrometer. A comparison showed the method was feasible. Finally, the γ-ray spectra of primary coolant were measured under normal operations and during fuel-rod failure. The two peaks of (135)Xe (249.8keV) and (88)Kr (2392.1keV) were visible, confirming that the method is capable of monitoring fuel-rod failure on-line. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Evaluation of Window Failure Modes

    DTIC Science & Technology

    1999-12-01

    U.S. Coast Guard Research and Development Center 1082 Shennecossett Road, Groton, CT 06340-6096 Report No. CG-D-08-00 EVALUATION OF WINDOW FAILURE...States Coast Guard Research & Development Center 1082 Shennecossett Road Groton, CT 06340-6096 11 I.Report No. CG-D-08-00 Technical Report...Development Center 1082 Shennecossett Road Groton,CT 06340-6096 12. Sponsoring Organization Name and Address U.S. Department of Transportation United

  15. Heart Failure

    MedlinePlus

    Heart failure is a condition in which the heart can't pump enough blood to meet the body's needs. Heart failure does not mean that your heart has stopped ... and shortness of breath Common causes of heart failure are coronary artery disease, high blood pressure and ...

  16. An evaluation of the pressure proof test concept for thin sheet 2024-T3

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Poe, C. C., Jr.; Newman, J. C., Jr.; Harris, C. E.

    1990-01-01

    The concept of pressure proof testing of fuselage structures with fatigue cracks to insure structural integrity was evaluated from a fracture mechanics viewpoint. A generic analytical and experimental investigation was conducted on uniaxially loaded flat panels with crack configurations and stress levels typical of longitudinal lap-splice joints in commercial transport aircraft fuselage. The results revealed that the remaining fatigue life after a proof test was longer than that without the proof test because of crack growth retardation due to increased crack closure. However, based on a crack length that is slightly less than the critical value at the maximum proof test stress, the minimum assured life or proof test interval must be no more than 550 pressure cycles for a 1.33 proof factor and 1530 pressure cycles for a 1.5 proof factor to prevent in-flight failures.

  17. An evaluation of the pressure proof test concept for thin sheet 2024-T3

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Poe, C. C., Jr.; Newman, James C., Jr.; Harris, Charles E.

    1990-01-01

    The concept of pressure proof testing of fuselage structures with fatigue cracks to insure structural integrity was evaluated from a fracture mechanics viewpoint. A generic analytical and experimental investigation was conducted on uniaxially loaded flat panels with crack configurations and stress levels typical of longitudinal lap splice joints in commercial transport aircraft fuselages. The results revealed that the remaining fatigue life after a proof test was longer than that without the proof test because of crack growth retardation due to increased crack closure. However, based on a crack length that is slightly less than the critical value at the maximum proof test stress, the minimum assured life or proof test interval must be no more than 550 pressure cycles for a 1.33 proof factor and 1530 pressure cycles for a 1.5 proof factor to prevent in-flight failures.

  18. Gaussian fitting for carotid and radial artery pressure waveforms: comparison between normal subjects and heart failure patients.

    PubMed

    Liu, Chengyu; Zheng, Dingchang; Zhao, Lina; Liu, Changchun

    2014-01-01

    It has been reported that Gaussian functions could accurately and reliably model both carotid and radial artery pressure waveforms (CAPW and RAPW). However, the physiological relevance of the characteristic features from the modeled Gaussian functions has been little investigated. This study thus aimed to determine characteristic features from the Gaussian functions and to make comparisons of them between normal subjects and heart failure patients. Fifty-six normal subjects and 51 patients with heart failure were studied with the CAPW and RAPW signals recorded simultaneously. The two signals were normalized first and then modeled by three positive Gaussian functions, with their peak amplitude, peak time, and half-width determined. Comparisons of these features were finally made between the two groups. Results indicated that the peak amplitude of the first Gaussian curve was significantly decreased in heart failure patients compared with normal subjects (P<0.001). Significantly increased peak amplitude of the second Gaussian curves (P<0.001) and significantly shortened peak times of the second and third Gaussian curves (both P<0.001) were also presented in heart failure patients. These results were true for both CAPW and RAPW signals, indicating the clinical significance of the Gaussian modeling, which should provide essential tools for further understanding the underlying physiological mechanisms of the artery pressure waveform.

  19. Interrelationship of Nondestructive Evaluation Methodologies Applied to Testing of Composite Overwrapped Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Leifeste, Mark R.

    2007-01-01

    Composite Overwrapped Pressure Vessels (COPVs) are commonly used in spacecraft for containment of pressurized gases and fluids, incorporating strength and weight savings. The energy stored is capable of extensive spacecraft damage and personal injury in the event of sudden failure. These apparently simple structures, composed of a metallic media impermeable liner and fiber/resin composite overwrap are really complex structures with numerous material and structural phenomena interacting during pressurized use which requires multiple, interrelated monitoring methodologies to monitor and understand subtle changes critical to safe use. Testing of COPVs at NASA Johnson Space Center White Sands T est Facility (WSTF) has employed multiple in-situ, real-time nondestructive evaluation (NDE) methodologies as well as pre- and post-test comparative techniques to monitor changes in material and structural parameters during advanced pressurized testing. The use of NDE methodologies and their relationship to monitoring changes is discussed based on testing of real-world spacecraft COPVs. Lessons learned are used to present recommendations for use in testing, as well as a discussion of potential applications to vessel health monitoring in future applications.

  20. Pressure ulcer-related pelvic osteomyelitis: evaluation of a two-stage surgical strategy (debridement, negative pressure therapy and flap coverage) with prolonged antimicrobial therapy.

    PubMed

    Andrianasolo, Johan; Ferry, Tristan; Boucher, Fabien; Chateau, Joseph; Shipkov, Hristo; Daoud, Fatiha; Braun, Evelyne; Triffault-Fillit, Claire; Perpoint, Thomas; Laurent, Frédéric; Mojallal, Alain-Ali; Chidiac, Christian; Valour, Florent

    2018-04-10

    A two-stage surgical strategy (debridement-negative pressure therapy (NPT) and flap coverage) with prolonged antimicrobial therapy is usually proposed in pressure ulcer-related pelvic osteomyelitis but has not been widely evaluated. Adult patients with pressure ulcer-related pelvic osteomyelitis treated by a two-stage surgical strategy were included in a retrospective cohort study. Determinants of superinfection (i.e., additional microbiological findings at reconstruction) and treatment failure were assessed using binary logistic regression and Kaplan-Meier curve analysis. Sixty-four pressure ulcer-related pelvic osteomyelitis in 61 patients (age, 47 (IQR, 36-63)) were included. Osteomyelitis was mostly polymicrobial (73%), with a predominance of S. aureus (47%), Enterobacteriaceae spp. (44%) and anaerobes (44%). Flap coverage was performed after 7 (IQR, 5-10) weeks of NPT, with 43 (68%) positive bone samples among which 39 (91%) were superinfections, associated with a high ASA score (OR, 5.8; p = 0.022). An increased prevalence of coagulase negative staphylococci (p = 0.017) and Candida spp. (p = 0.003) was observed at time of flap coverage. An ESBL Enterobacteriaceae spp. was found in 5 (12%) patients, associated with fluoroquinolone consumption (OR, 32.4; p = 0.005). Treatment duration was as 20 (IQR, 14-27) weeks, including 11 (IQR, 8-15) after reconstruction. After a follow-up of 54 (IQR, 27-102) weeks, 15 (23%) failures were observed, associated with previous pressure ulcer (OR, 5.7; p = 0.025) and Actinomyces spp. infection (OR, 9.5; p = 0.027). Pressure ulcer-related pelvic osteomyelitis is a difficult-to-treat clinical condition, generating an important consumption of broad-spectrum antibiotics. The lack of correlation between outcome and the debridement-to-reconstruction interval argue for a short sequence to limit the total duration of treatment.

  1. Failure pressures after repairs of 2-cm × 2.5-cm rhinologic dural defects in a porcine ex vivo model.

    PubMed

    Lin, Ryan P; Weitzel, Erik Kent; Chen, Philip G; McMains, Kevin Christopher; Chang, Daniel R; Braxton, Ernest E; Majors, Jacob; Bunegin, Leon

    2016-10-01

    The objective of this study was to determine failure pressures of 6 rhinologic repair techniques of large skull base/dural defects in a controlled, ex vivo model. Failure pressures of 6 dural repairs in a porcine model were studied using a closed testing apparatus; 24-mm × 19-mm dural defects were created; 40-mm × 34-mm grafts composed of porcine Duragen (Integra), fascia lata, and Biodesign (Cook) were used either with or without Tisseel (Baxter International Inc.) to create 6 repairs: Duragen/no glue (D/NG), Duragen/Tisseel (D/T), fascia lata/no glue (FL/NG), fascia lata/Tisseel (FL/T), Biodesign/no glue (B/NG), and Biodesign/Tisseel (B/T). Saline was infused at 30 mL/hour, applying even force to the underside of the graft until repair failure. Five trials were performed per repair type for a total of 30 repairs. Mean failure pressures were as follows: D/NG 1.361 ± 0.169 cmH 2 O; D/T 9.127 ± 1.805 cmH 2 O; FL/NG 0.200 ± 0.109 cmH 2 O; FL/T 7.833 ± 2.657 cmH 2 O; B/NG 0.299 ± 0.109 cmH 2 O; and B/T 2.67 ± 0.619 cmH 2 O. There were statistically significant differences between glued (Tisseel) and non-glued repairs for each repair category (p < 0.05). All glued repairs performed better than non-glued repairs. Both D/T and FL/T repairs performed better than B/T repairs. No repair tolerated pressures throughout the full range of adult supine intracranial pressure. © 2016 ARS-AAOA, LLC.

  2. Importance Sampling in the Evaluation and Optimization of Buffered Failure Probability

    DTIC Science & Technology

    2015-07-01

    12th International Conference on Applications of Statistics and Probability in Civil Engineering, ICASP12 Vancouver, Canada, July 12-15, 2015...Importance Sampling in the Evaluation and Optimization of Buffered Failure Probability Marwan M. Harajli Graduate Student, Dept. of Civil and Environ...criterion is usually the failure probability . In this paper, we examine the buffered failure probability as an attractive alternative to the failure

  3. Shock-absorbing and failure mechanisms of WS2 and MoS2 nanoparticles with fullerene-like structures under shock wave pressure.

    PubMed

    Zhu, Yan Qiu; Sekine, Toshimori; Li, Yan Hui; Fay, Michael W; Zhao, Yi Min; Patrick Poa, C H; Wang, Wen Xin; Roe, Martin J; Brown, Paul D; Fleischer, Niles; Tenne, Reshef

    2005-11-23

    The excellent shock-absorbing performance of WS2 and MoS2 nanoparticles with inorganic fullerene-like structures (IFs) under very high shock wave pressures of 25 GPa is described. The combined techniques of X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, thermal analysis, and transmission electron microscopy have been used to evaluate the diverse, intriguing features of shock recovered IFs, of interest for their tribological applications, thereby allowing improved understanding of their antishock behavior and structure-property relationships. Two possible failure mechanisms are proposed and discussed. The supershock-absorbing ability of the IF-WS2 enables them to survive pressures up to 25 GPa accompanied with concurrent temperatures of up to 1000 degrees C without any significant structural degradation or phase change making them probably the strongest cage molecules now known.

  4. Burst Pressure Failure of Titanium Tanks Damaged by Secondary Plumes from Hypervelocity Impacts on Aluminum Shields

    NASA Technical Reports Server (NTRS)

    Nahra, Henry; Ghosn, Louis; Christiansen, Eric; Davis, B. Alan; Keddy, Chris; Rodriquez, Karen; Miller, Joshua; Bohl, William

    2011-01-01

    Metallic pressure tanks used in space missions are inherently vulnerable to hypervelocity impacts from micrometeoroids and orbital debris; thereby knowledge of impact damage and its effect on the tank integrity is crucial to a spacecraft risk assessment. This paper describes tests that have been performed to assess the effects of hypervelocity impact (HVI) damage on Titanium alloy (Ti-6Al-4V) pressure vessels burst pressure and characteristics. The tests consisted of a pair of HVI impact tests on water-filled Ti-6Al-4V tanks (water being used as a surrogate to the actual propellant) and subsequent burst tests as well as a burst test on an undamaged control tank. The tanks were placed behind Aluminum (Al) shields and then each was impacted with a 7 km/s projectile. The resulting impact debris plumes partially penetrated the Ti-6Al-4V tank surfaces resulting in a distribution of craters. During the burst tests, the tank that failed at a lower burst pressure did appear to have the failure initiating at a crater site with observed spall cracks. A fracture mechanics analysis showed that the tanks failure at the impact location may have been due to a spall crack that formed upon impact of a fragmentation on the Titanium surface. This result was corroborated with a finite element analysis from calculated Von-Mises and hoop stresses.

  5. Review of reactor pressure vessel evaluation report for Yankee Rowe Nuclear Power Station (YAEC No. 1735)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cheverton, R.D.; Dickson, T.L.; Merkle, J.G.

    1992-03-01

    The Yankee Atomic Electric Company has performed an Integrated Pressurized Thermal Shock (IPTS)-type evaluation of the Yankee Rowe reactor pressure vessel in accordance with the PTS Rule (10 CFR 50. 61) and a US Regulatory Guide 1.154. The Oak Ridge National Laboratory (ORNL) reviewed the YAEC document and performed an independent probabilistic fracture-mechnics analysis. The review included a comparison of the Pacific Northwest Laboratory (PNL) and the ORNL probabilistic fracture-mechanics codes (VISA-II and OCA-P, respectively). The review identified minor errors and one significant difference in philosophy. Also, the two codes have a few dissimilar peripheral features. Aside from these differences,more » VISA-II and OCA-P are very similar and with errors corrected and when adjusted for the difference in the treatment of fracture toughness distribution through the wall, yield essentially the same value of the conditional probability of failure. The ORNL independent evaluation indicated RT{sub NDT} values considerably greater than those corresponding to the PTS-Rule screening criteria and a frequency of failure substantially greater than that corresponding to the primary acceptance criterion'' in US Regulatory Guide 1.154. Time constraints, however, prevented as rigorous a treatment as the situation deserves. Thus, these results are very preliminary.« less

  6. Review of reactor pressure vessel evaluation report for Yankee Rowe Nuclear Power Station (YAEC No. 1735)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cheverton, R.D.; Dickson, T.L.; Merkle, J.G.

    1992-03-01

    The Yankee Atomic Electric Company has performed an Integrated Pressurized Thermal Shock (IPTS)-type evaluation of the Yankee Rowe reactor pressure vessel in accordance with the PTS Rule (10 CFR 50. 61) and a US Regulatory Guide 1.154. The Oak Ridge National Laboratory (ORNL) reviewed the YAEC document and performed an independent probabilistic fracture-mechnics analysis. The review included a comparison of the Pacific Northwest Laboratory (PNL) and the ORNL probabilistic fracture-mechanics codes (VISA-II and OCA-P, respectively). The review identified minor errors and one significant difference in philosophy. Also, the two codes have a few dissimilar peripheral features. Aside from these differences,more » VISA-II and OCA-P are very similar and with errors corrected and when adjusted for the difference in the treatment of fracture toughness distribution through the wall, yield essentially the same value of the conditional probability of failure. The ORNL independent evaluation indicated RT{sub NDT} values considerably greater than those corresponding to the PTS-Rule screening criteria and a frequency of failure substantially greater than that corresponding to the ``primary acceptance criterion`` in US Regulatory Guide 1.154. Time constraints, however, prevented as rigorous a treatment as the situation deserves. Thus, these results are very preliminary.« less

  7. Physical Exercise and Patients with Chronic Renal Failure: A Meta-Analysis.

    PubMed

    Qiu, Zhenzhen; Zheng, Kai; Zhang, Haoxiang; Feng, Ji; Wang, Lizhi; Zhou, Hao

    2017-01-01

    Chronic renal failure is a severe clinical problem which has some significant socioeconomic impact worldwide and hemodialysis is an important way to maintain patients' health state, but it seems difficult to get better in short time. Considering these, the aim in our research is to update and evaluate the effects of exercise on the health of patients with chronic renal failure. The databases were used to search for the relevant studies in English or Chinese. And the association between physical exercise and health state of patients with chronic renal failure has been investigated. Random-effect model was used to compare the physical function and capacity in exercise and control groups. Exercise is helpful in ameliorating the situation of blood pressure in patients with renal failure and significantly reduces VO 2 in patients with renal failure. The results of subgroup analyses show that, in the age >50, physical activity can significantly reduce blood pressure in patients with renal failure. The activity program containing warm-up, strength, and aerobic exercises has benefits in blood pressure among sick people and improves their maximal oxygen consumption level. These can help patients in physical function and aerobic capacity and may give them further benefits.

  8. Lifelong Cyclic Mechanical Strain Promotes Large Elastic Artery Stiffening: Increased Pulse Pressure and Old Age-Related Organ Failure.

    PubMed

    Thorin-Trescases, Nathalie; Thorin, Eric

    2016-05-01

    The arterial wall is under a huge mechanical constraint imposed by the cardiac cycle that is bound to generate damage with time. Each heartbeat indeed imposes a pulsatile pressure that generates a vascular stretch. Lifetime accumulation of pulsatile stretches will eventually induce fatigue of the elastic large arterial walls, such as aortic and carotid artery walls, promoting their stiffening that will gradually perturb the normal blood flow and local pressure within the organs, and lead to organ failure. The augmented pulse pressure induced by arterial stiffening favours left ventricular hypertrophy because of the repeated extra work against stiff high-pressure arteries, and tissue damage as a result of excessive pulsatile pressure transmitted into the microcirculation, especially in low resistance/high-flow organs such as the brain and kidneys. Vascular aging is therefore characterized by the stiffening of large elastic arteries leading to a gradual increase in pulse pressure with age. In this review we focus on the effect of age-related stiffening of large elastic arteries. We report the clinical evidence linking arterial stiffness and organ failure and discuss the molecular pathways that are activated by the increase of mechanical stress in the wall. We also discuss the possible interventions that could limit arterial stiffening with age, such as regular aerobic exercise training, and some pharmacological approaches. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  9. An evaluation of the pressure proof test concept for 2024-T3 aluminium alloy sheet

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Poe, C. C., Jr.; Newman, J. C.; Harris, C. E.

    1991-01-01

    The concept of pressure proof testing of fuselage structures with fatigue cracks to insure structural integrity was evaluated from a fracture mechanics viewpoint. A generic analytical and experimental investigation was conducted on uniaxially loaded flat panels with crack configurations and stress levels typical of longitudinal lap splice joints in commercial transport aircraft fuselages. The results revealed that the remaining fatigue life after a proof cycle was longer than that without the proof cycle because of crack growth retardation due to increased crack closure. However, based on a crack length that is slightly less than the critical value at the maximum proof stress, the minimum assured life or proof test interval must be no more than 550 pressure cycles for a 1.33 proof factor and 1530 pressure cycles for a 1.5 proof factor to prevent in-flight failures.

  10. Acute Effects of Continuous Positive Air way Pressure on Pulse Pressure in Chronic Heart Failure

    PubMed Central

    Quintão, Mônica; Chermont, Sérgio; Marchese, Luana; Brandão, Lúcia; Bernardez, Sabrina Pereira; Mesquita, Evandro Tinoco; Rocha, Nazareth de Novaes; Nóbrega, Antônio Claudio L.

    2014-01-01

    Background Patients with heart failure (HF) have left ventricular dysfunction and reduced mean arterial pressure (MAP). Increased adrenergic drive causes vasoconstriction and vessel resistance maintaining MAP, while increasing peripheral vascular resistance and conduit vessel stiffness. Increased pulse pressure (PP) reflects a complex interaction of the heart with the arterial and venous systems. Increased PP is an important risk marker in patients with chronic HF (CHF). Non-invasive ventilation (NIV) has been used for acute decompensated HF, to improve congestion and ventilation through both respiratory and hemodynamic effects. However, none of these studies have reported the effect of NIV on PP. Objective The objective of this study was to determine the acute effects of NIV with CPAP on PP in outpatients with CHF. Methods Following a double-blind, randomized, cross-over, and placebo-controlled protocol, twenty three patients with CHF (17 males; 60 ± 11 years; BMI 29 ± 5 kg/cm2, NYHA class II, III) underwent CPAP via nasal mask for 30 min in a recumbent position. Mask pressure was 6 cmH2O, whereas placebo was fixed at 0-1 cmH2O. PP and other non invasive hemodynamics variables were assessed before, during and after placebo and CPAP mode. Results CPAP decreased resting heart rate (Pre: 72 ± 9; vs. Post 5 min: 67 ± 10 bpm; p < 0.01) and MAP (CPAP: 87 ± 11; vs. control 96 ± 11 mmHg; p < 0.05 post 5 min). CPAP decreased PP (CPAP: 47 ± 20 pre to 38 ± 19 mmHg post; vs. control: 42 ± 12 mmHg, pre to 41 ± 18 post p < 0.05 post 5 min). Conclusion NIV with CPAP decreased pulse pressure in patients with stable CHF. Future clinical trials should investigate whether this effect is associated with improved clinical outcome. PMID:24676373

  11. Photomultiplier tube failure under hydrostatic pressure in future neutrino detectors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chambliss, K.; Diwan, M.; Simos, N.

    Failure of photomultiplier tubes (PMTs) under hydrostatic pressure is a concern in neutrino detection, specifically, in the proposed Long-Baseline Neutrino Experiment project. Controlled hydrostatic implosion tests were performed on prototypic PMT bulbs of 10-inch diameter and recorded using high speed filming techniques to capture failures in detail. These high-speed videos were analyzed frame-by-frame in order to identify the origin of a crack, measure the progression of individual crack along the surface of the bulb as it propagates through the glass, and estimate crack velocity. Crack velocity was calculated for each individual crack, and an average velocity was determined for allmore » measurable cracks on each bulb. Overall, 32 cracks were measured in 9 different bulbs tested. Finite element modeling (FEM) of crack formation and growth in prototypic PMT shows stress concentration near the middle section of the PMT bulbs that correlates well with our crack velocity measurements in that section. The FEM model predicts a crack velocity value that is close to the terminal crack velocity reported. Our measurements also reveal significantly reduced crack velocities compared to terminal crack velocities measured in glasses using fracture mechanics testing and reported in literature.« less

  12. Photomultiplier tube failure under hydrostatic pressure in future neutrino detectors

    DOE PAGES

    Chambliss, K.; Diwan, M.; Simos, N.; ...

    2014-10-09

    Failure of photomultiplier tubes (PMTs) under hydrostatic pressure is a concern in neutrino detection, specifically, in the proposed Long-Baseline Neutrino Experiment project. Controlled hydrostatic implosion tests were performed on prototypic PMT bulbs of 10-inch diameter and recorded using high speed filming techniques to capture failures in detail. These high-speed videos were analyzed frame-by-frame in order to identify the origin of a crack, measure the progression of individual crack along the surface of the bulb as it propagates through the glass, and estimate crack velocity. Crack velocity was calculated for each individual crack, and an average velocity was determined for allmore » measurable cracks on each bulb. Overall, 32 cracks were measured in 9 different bulbs tested. Finite element modeling (FEM) of crack formation and growth in prototypic PMT shows stress concentration near the middle section of the PMT bulbs that correlates well with our crack velocity measurements in that section. The FEM model predicts a crack velocity value that is close to the terminal crack velocity reported. Our measurements also reveal significantly reduced crack velocities compared to terminal crack velocities measured in glasses using fracture mechanics testing and reported in literature.« less

  13. A preliminary evaluation of a failure detection filter for detecting and identifying control element failures in a transport aircraft

    NASA Technical Reports Server (NTRS)

    Bundick, W. T.

    1985-01-01

    The application of the failure detection filter to the detection and identification of aircraft control element failures was evaluated in a linear digital simulation of the longitudinal dynamics of a B-737 Aircraft. Simulation results show that with a simple correlator and threshold detector used to process the filter residuals, the failure detection performance is seriously degraded by the effects of turbulence.

  14. A comparison of synchronized intermittent mandatory ventilation and pressure-regulated volume control ventilation in elderly patients with acute exacerbations of COPD and respiratory failure

    PubMed Central

    Chang, Suchi; Shi, Jindong; Fu, Cuiping; Wu, Xu; Li, Shanqun

    2016-01-01

    Background COPD is the third leading cause of death worldwide. Acute exacerbations of COPD may cause respiratory failure, requiring intensive care unit admission and mechanical ventilation. Intensive care unit patients with acute exacerbations of COPD requiring mechanical ventilation have higher mortality rates than other hospitalized patients. Although mechanical ventilation is the most effective intervention for these conditions, invasive ventilation techniques have yielded variable effects. Objective We evaluated pressure-regulated volume control (PRVC) ventilation treatment efficacy and preventive effects on pulmonary barotrauma in elderly COPD patients with respiratory failure. Patients and methods Thirty-nine intubated patients were divided into experimental and control groups and treated with the PRVC and synchronized intermittent mandatory ventilation – volume control methods, respectively. Vital signs, respiratory mechanics, and arterial blood gas analyses were monitored for 2–4 hours and 48 hours. Results Both groups showed rapidly improved pH, partial pressure of oxygen (PaO2), and PaO2 per fraction of inspired O2 levels and lower partial pressure of carbon dioxide (PaCO2) levels. The pH and PaCO2 levels at 2–4 hours were lower and higher, respectively, in the test group than those in the control group (P<0.05 for both); after 48 hours, blood gas analyses showed no statistical difference in any marker (P>0.05). Vital signs during 2–4 hours and 48 hours of treatment showed no statistical difference in either group (P>0.05). The level of peak inspiratory pressure in the experimental group after mechanical ventilation for 2–4 hours and 48 hours was significantly lower than that in the control group (P<0.05), while other variables were not significantly different between groups (P>0.05). Conclusion Among elderly COPD patients with respiratory failure, application of PRVC resulted in rapid improvement in arterial blood gas analyses while maintaining

  15. A comparison of synchronized intermittent mandatory ventilation and pressure-regulated volume control ventilation in elderly patients with acute exacerbations of COPD and respiratory failure.

    PubMed

    Chang, Suchi; Shi, Jindong; Fu, Cuiping; Wu, Xu; Li, Shanqun

    2016-01-01

    COPD is the third leading cause of death worldwide. Acute exacerbations of COPD may cause respiratory failure, requiring intensive care unit admission and mechanical ventilation. Intensive care unit patients with acute exacerbations of COPD requiring mechanical ventilation have higher mortality rates than other hospitalized patients. Although mechanical ventilation is the most effective intervention for these conditions, invasive ventilation techniques have yielded variable effects. We evaluated pressure-regulated volume control (PRVC) ventilation treatment efficacy and preventive effects on pulmonary barotrauma in elderly COPD patients with respiratory failure. Thirty-nine intubated patients were divided into experimental and control groups and treated with the PRVC and synchronized intermittent mandatory ventilation - volume control methods, respectively. Vital signs, respiratory mechanics, and arterial blood gas analyses were monitored for 2-4 hours and 48 hours. Both groups showed rapidly improved pH, partial pressure of oxygen (PaO2), and PaO2 per fraction of inspired O2 levels and lower partial pressure of carbon dioxide (PaCO2) levels. The pH and PaCO2 levels at 2-4 hours were lower and higher, respectively, in the test group than those in the control group (P<0.05 for both); after 48 hours, blood gas analyses showed no statistical difference in any marker (P>0.05). Vital signs during 2-4 hours and 48 hours of treatment showed no statistical difference in either group (P>0.05). The level of peak inspiratory pressure in the experimental group after mechanical ventilation for 2-4 hours and 48 hours was significantly lower than that in the control group (P<0.05), while other variables were not significantly different between groups (P>0.05). Among elderly COPD patients with respiratory failure, application of PRVC resulted in rapid improvement in arterial blood gas analyses while maintaining a low peak inspiratory pressure. PRVC can reduce pulmonary barotrauma

  16. Different components of blood pressure are associated with increased risk of atherosclerotic cardiovascular disease versus heart failure in advanced chronic kidney disease

    PubMed Central

    Bansal, Nisha; McCulloch, Charles E.; Lin, Feng; Robinson-Cohen, Cassianne; Rahman, Mahboob; Kusek, John W.; Anderson, Amanda H.; Xie, Dawei; Townsend, Raymond R.; Lora, Claudia M.; Wright, Jackson; Go, Alan S.; Ojo, Akinlolu; Alper, Arnold; Lustigova, Eva; Cuevas, Magda; Kallem, Radhakrishna; Hsu, Chi-yuan

    2016-01-01

    Blood pressure is a modifiable risk for cardiovascular disease (CVD). Among hemodialysis patients, there is a U-shaped association between blood pressure and risk of death. However, few studies have examined the association between blood pressure and CVD in patients with stage 4 and 5 chronic kidney disease. Here we studied 1,795 Chronic Renal Insufficiency Cohort (CRIC) Study participants with estimated glomerular filtration rate under 30 ml/min/1.73 m2 and not on dialysis. The association of systolic (SBP), diastolic (DBP) and pulse pressure with risk of physician-adjudicated atherosclerotic CVD (stroke, myocardial infarction or peripheral arterial disease) and heart failure were tested using Cox regression adjusted for demographics, comorbidity and medications. There was a significant association with higher SBP (adjusted hazard ratio 2.04 [95% confidence interval: 1.46, 2.84]) for SBP over 140 vs under 120 mmHg, higher DBP (2.52 [1.54, 4.11]) for DBP over 90 vs under 80 mmHg and higher pulse pressure (2.67 [1.82, 3.92]) for pulse pressure over 68 vs under 51 mmHg with atherosclerotic CVD. For heart failure, there was a significant association with higher pulse pressure only (1.42 [1.05, 1.92]) for pulse pressure over 68 vs under 51 mmHg, but not for SBP or DBP. Thus, among participants with stage 4 and 5 chronic kidney disease, there was an independent association between higher SBP, DBP and pulse pressure with risk of atherosclerotic CVD, while only higher pulse pressure was independently associated with greater risk of heart failure. Further trials are needed to determine whether aggressive reduction of blood pressure reduces the risk of CVD events in patients with stage 4 and 5 chronic kidney disease. PMID:27717485

  17. Forecasting volcanic eruptions and other material failure phenomena: An evaluation of the failure forecast method

    NASA Astrophysics Data System (ADS)

    Bell, Andrew F.; Naylor, Mark; Heap, Michael J.; Main, Ian G.

    2011-08-01

    Power-law accelerations in the mean rate of strain, earthquakes and other precursors have been widely reported prior to material failure phenomena, including volcanic eruptions, landslides and laboratory deformation experiments, as predicted by several theoretical models. The Failure Forecast Method (FFM), which linearizes the power-law trend, has been routinely used to forecast the failure time in retrospective analyses; however, its performance has never been formally evaluated. Here we use synthetic and real data, recorded in laboratory brittle creep experiments and at volcanoes, to show that the assumptions of the FFM are inconsistent with the error structure of the data, leading to biased and imprecise forecasts. We show that a Generalized Linear Model method provides higher-quality forecasts that converge more accurately to the eventual failure time, accounting for the appropriate error distributions. This approach should be employed in place of the FFM to provide reliable quantitative forecasts and estimate their associated uncertainties.

  18. Implantable Hemodynamic Monitoring for Heart Failure Patients.

    PubMed

    Abraham, William T; Perl, Leor

    2017-07-18

    Rates of heart failure hospitalization remain unacceptably high. Such hospitalizations are associated with substantial patient, caregiver, and economic costs. Randomized controlled trials of noninvasive telemedical systems have failed to demonstrate reduced rates of hospitalization. The failure of these technologies may be due to the limitations of the signals measured. Intracardiac and pulmonary artery pressure-guided management has become a focus of hospitalization reduction in heart failure. Early studies using implantable hemodynamic monitors demonstrated the potential of pressure-based heart failure management, whereas subsequent studies confirmed the clinical utility of this approach. One large pivotal trial proved the safety and efficacy of pulmonary artery pressure-guided heart failure management, showing a marked reduction in heart failure hospitalizations in patients randomized to active pressure-guided management. "Next-generation" implantable hemodynamic monitors are in development, and novel approaches for the use of this data promise to expand the use of pressure-guided heart failure management. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  19. Ratio of Systolic Blood Pressure to Right Atrial Pressure, a Novel Marker to Predict Morbidity and Mortality in Acute Systolic Heart Failure.

    PubMed

    Omar, Hesham R; Charnigo, Richard; Guglin, Maya

    2017-04-01

    Congestion is the main contributor to heart failure (HF) morbidity and mortality. We assessed the combined role of congestion and decreased forward flow in predicting morbidity and mortality in acute systolic HF. The Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness trial data set was used to determine if the ratio of simultaneously measured systolic blood pressure (SBP)/right atrial pressure (RAP) on admission predicted HF rehospitalization and 6-month mortality. One hundred ninety-five patients (mean age 56.5 years, 75% men) who received pulmonary artery catheterization were studied. The RAP, SBP, and SBP/RAP had an area under the curve (AUC) of 0.593 (p = 0.0205), 0.585 (p = 0.0359), and 0.621 (p = 0.0026), respectively, in predicting HF rehospitalization. The SBP/RAP was a superior marker of HF rehospitalization compared with RAP alone (difference in AUC 0.0289, p = 0.0385). The optimal criterion of SBP/RAP <11 provided the highest combined sensitivity (77.1%) and specificity (50.9%) in predicting HF rehospitalization. The SBP/RAP had an AUC 0.622, p = 0.0108, and a cut-off value of SBP/RAP <8 had a sensitivity of 61.9% and specificity 64.1% in predicting mortality. Multivariate analysis showed that an SBP/RAP <11 independently predicted rehospitalization for HF (estimated odds ratio 3.318, 95% confidence interval 1.692 to 6.506, p = 0.0005) and an SBP/RAP <8 independently predicted mortality (estimated hazard ratio 2.025, 95% confidence interval 1.069 to 3.833, p = 0.030). In conclusion, SBP/RAP ratio is a marker that identifies a spectrum of complications after hospitalization of patients with decompensated systolic HF, starting with increased incidence of HF rehospitalization at SBP/RAP <11 to increased mortality with SBP/RAP <8. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Physical Exercise and Patients with Chronic Renal Failure: A Meta-Analysis

    PubMed Central

    Qiu, Zhenzhen; Zheng, Kai; Zhang, Haoxiang; Feng, Ji; Wang, Lizhi

    2017-01-01

    Chronic renal failure is a severe clinical problem which has some significant socioeconomic impact worldwide and hemodialysis is an important way to maintain patients' health state, but it seems difficult to get better in short time. Considering these, the aim in our research is to update and evaluate the effects of exercise on the health of patients with chronic renal failure. The databases were used to search for the relevant studies in English or Chinese. And the association between physical exercise and health state of patients with chronic renal failure has been investigated. Random-effect model was used to compare the physical function and capacity in exercise and control groups. Exercise is helpful in ameliorating the situation of blood pressure in patients with renal failure and significantly reduces VO2 in patients with renal failure. The results of subgroup analyses show that, in the age >50, physical activity can significantly reduce blood pressure in patients with renal failure. The activity program containing warm-up, strength, and aerobic exercises has benefits in blood pressure among sick people and improves their maximal oxygen consumption level. These can help patients in physical function and aerobic capacity and may give them further benefits. PMID:28316986

  1. An Educational Intervention to Evaluate Nurses' Knowledge of Heart Failure.

    PubMed

    Sundel, Siobhan; Ea, Emerson E

    2018-07-01

    Nurses are the main providers of patient education in inpatient and outpatient settings. Unfortunately, nurses may lack knowledge of chronic medical conditions, such as heart failure. The purpose of this one-group pretest-posttest intervention was to determine the effectiveness of teaching intervention on nurses' knowledge of heart failure self-care principles in an ambulatory care setting. The sample consisted of 40 staff nurses in ambulatory care. Nurse participants received a focused education intervention based on knowledge deficits revealed in the pretest and were then resurveyed within 30 days. Nurses were evaluated using the valid and reliable 20-item Nurses Knowledge of Heart Failure Education Principles Survey tool. The results of this project demonstrated that an education intervention on heart failure self-care principles improved nurses' knowledge of heart failure in an ambulatory care setting, which was statistically significant (p < .05). Results suggest that a teaching intervention could improve knowledge of heart failure, which could lead to better patient education and could reduce patient readmission for heart failure. J Contin Educ Nurs. 2018;49(7):315-321. Copyright 2018, SLACK Incorporated.

  2. Nocturnal blood pressure non-dipping is not associated with increased left ventricular mass index in hypertensive children without end-stage renal failure.

    PubMed

    Seeman, Tomáš; Hradský, Ondřej; Gilík, Jiří

    2016-08-01

    The aim of our study was to investigate whether nocturnal blood pressure (BP) dip is associated with increased left ventricular mass index and hypertrophy in children with hypertension (HT). We retrospectively reviewed data from all children with confirmed ambulatory HT in our center and performed ambulatory blood pressure monitoring (ABPM) and echocardiography at the same time. Left ventricular hypertrophy (LVH) was defined as left ventricular mass index (LVMI) ≥95th centile. Non-dipping phenomenon was defined as nocturnal BP dip <10 %. A total of 114 ABPM studies were included, the median age of children was 15.3 years (3.8-18.9), 80 children had renoparenchymal HT without end-stage renal failure, 34 had primary HT, and 27 studies were done on untreated children and 87 on treated children. Non-dipping phenomenon was present in 63 (55 %) studies (non-dippers). The LVMI adjusted for age was not significantly different between non-dippers and dippers (0.87 ± 0.03 vs. 0.81 ± 0.02, p = 0.13). Left ventricular hypertrophy was not significantly higher in non-dippers than in dippers (20 vs. 9 %, p = 0.12). Hypertensive children without end-stage renal failure with non-dipping phenomenon do not have increased prevalence of LVH or higher LVMI adjusted for age than hypertensive children with preserved nocturnal BP dip. • Adult and pediatric hypertensive patients with end-stage renal failure have often nocturnal blood pressure non-dipping phenomenon. • Non-dipping phenomenon is in patients with end-stage renal failure associated with increased prevalence of left ventricular hypertrophy. What is New: • Pediatric hypertensive patients without end-stage renal failure with blood pressure non-dipping phenomenon do not have increased prevalence of left ventricular hypertrophy.

  3. Sildenafil ameliorates left ventricular T-tubule remodeling in a pressure overload-induced murine heart failure model

    PubMed Central

    Huang, Chun-kai; Chen, Bi-yi; Guo, Ang; Chen, Rong; Zhu, Yan-qi; Kutschke, William; Hong, Jiang; Song, Long-sheng

    2016-01-01

    Aim: Sildenafil, a phosphodiesterase 5 (PDE5) inhibitor, has been shown to exert beneficial effects in heart failure. The purpose of this study was to test whether sildenafil suppressed transverse-tubule (T-tubule) remodeling in left ventricular (LV) failure and thereby providing the therapeutic benefits. Methods: A pressure overload-induced murine heart failure model was established in mice by thoracic aortic banding (TAB). One day after TAB, the mice received sildenafil (100 mg·kg−1·d−1, sc) or saline for 5 weeks. At the end of treatment, echocardiography was used to examine LV function. Then the intact hearts were dissected out and placed in Langendorff-perfusion chamber for in situ confocal imaging of T-tubule ultrastructure from epicardial myocytes. Results: TAB surgery resulted in heart failure accompanied by remarkable T-tubule remodeling. Sildenafil treatment significantly attenuated TAB-induced cardiac hypertrophy and congestive heart failure, improved LV contractile function, and preserved T-tubule integrity in LV cardiomyocytes. But sildenafil treatment did not significantly affect the chamber dilation. The integrity of LV T-tubule structure was correlated with cardiac hypertrophy (R2=0.74, P<0.01) and global LV function (R2=0.47, P<0.01). Conclusion: Sildenafil effectively ameliorates LV T-tubule remodeling in TAB mice, revealing a novel mechanism underlying the therapeutic benefits of sildenafil in heart failure. PMID:26972492

  4. Efficacy and Safety of Renal Sympathetic Denervation on Dogs with Pressure Overload-Induced Heart Failure.

    PubMed

    Chen, Pingan; Leng, Shuilong; Luo, Yishan; Li, Shaonan; Huang, Zicheng; Liu, Zhenxi; Liu, Zhen; Wang, Jie; Lei, Xiaoming

    2017-02-01

    In dogs with heart failure (HF) induced by overload pressure, the role of renal sympathetic denervation (RSD) on heart failure and in the renal artery is unclear. Therefore, we investigated the efficacy and safety of RSD in dogs with pressure overload-induced heart failure. Twenty mongrel dogs were divided into a sham-operated group, an HF group and an HF + RSD group. In the sham-operated group, the abdominal aorta was located but was not constricted, in the HF group, the abdominal aorta was constricted without RSD, and the HF+RSD group underwent RSD with constriction of the abdominal aorta after 10 weeks. Blood sampling assays, echocardiography, intravascular ultrasound (IVUS) measurement and histopathological examination were performed. Renal sympathetic denervation caused a significant reduction in the levels of noradrenaline (166.62±6.84 vs. 183.48±13.66 pg/ml, P<0.05), plasma renin activity (1.93±0.12 vs. 2.10±0.13 ng/mlh, P<0.05) and B-type natriuretic peptide (71.14±3.86 vs. 83.15±5.73 pg/ml, P<0.05) at eight weeks after RSD in the HF+RSD group. Compared with the HF group at eight weeks, the left ventricular internal dimension at end-diastole and end-systole were lower and the left ventricular ejection fraction was higher (all P<0.05) at eight weeks after RSD in the HF+RSD group. Intravenous ultrasound images showed no changes in the renal artery lumen, and intimal hyperplasia and vascular lumen stenosis were not observed after RSD. Renal sympathetic denervation could improve cardiac function in dogs with HF induced by pressure overload; RSD had no adverse influence on the renal artery. Copyright © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  5. The effect of preignition on cylinder temperatures, pressures, power output, and piston failures

    NASA Technical Reports Server (NTRS)

    Corrington, Lester C; Fisher, William F

    1947-01-01

    An investigation was conducted using a cylinder of a V-type liquid-cooled engine to observe the behavior of the cylinder when operated under preignition conditions. Data were recorded that showed cylinder-head temperatures, time of ignition, engine speed, power output, and change in maximum cylinder pressure as a function of time as the engine entered preignition and was allowed to operate under preignition conditions for a short time. The effects of the following variables on the engine behavior during preignition were investigated: fuel-air ratio, power level, aromatic content of fuel, engine speed, mixture temperature, and preignition source. The power levels at which preignition would cause complete piston failure for the selected engine operating conditions and the types of failure encountered when using various values of clearance between the piston and cylinder barrel were determined. The fuels used had performance numbers high enough to preclude any possibility of knock throughout the test program.

  6. Implant experience with an implantable hemodynamic monitor for the management of symptomatic heart failure.

    PubMed

    Steinhaus, David; Reynolds, Dwight W; Gadler, Fredrik; Kay, G Neal; Hess, Mike F; Bennett, Tom

    2005-08-01

    Management of congestive heart failure is a serious public health problem. The use of implantable hemodynamic monitors (IHMs) may assist in this management by providing continuous ambulatory filling pressure status for optimal volume management. The Chronicle system includes an implanted monitor, a pressure sensor lead with passive fixation, an external pressure reference (EPR), and data retrieval and viewing components. The tip of the lead is placed near the right ventricular outflow tract to minimize risk of sensor tissue encapsulation. Implant technique and lead placement is similar to that of a permanent pacemaker. After the system had been successfully implanted in 148 patients, the type and frequency of implant-related adverse events were similar to a single-chamber pacemaker implant. R-wave amplitude was 15.2 +/- 6.7 mV and the pressure waveform signal was acceptable in all but two patients in whom presence of artifacts required lead repositioning. Implant procedure time was not influenced by experience, remaining constant throughout the study. Based on this evaluation, permanent placement of an IHM in symptomatic heart failure patients is technically feasible. Further investigation is warranted to evaluate the use of the continuous hemodynamic data in management of heart failure patients.

  7. Mitochondrial reactive oxygen species production and respiratory complex activity in rats with pressure overload-induced heart failure

    PubMed Central

    Schwarzer, Michael; Osterholt, Moritz; Lunkenbein, Anne; Schrepper, Andrea; Amorim, Paulo; Doenst, Torsten

    2014-01-01

    We investigated the impact of cardiac reactive oxygen species (ROS) during the development of pressure overload-induced heart failure. We used our previously described rat model where transverse aortic constriction (TAC) induces compensated hypertrophy after 2 weeks, heart failure with preserved ejection fraction at 6 and 10 weeks, and heart failure with systolic dysfunction after 20 weeks. We measured mitochondrial ROS production rates, ROS damage and assessed the therapeutic potential of in vivo antioxidant therapies. In compensated hypertrophy (2 weeks of TAC) ROS production rates were normal at both mitochondrial ROS production sites (complexes I and III). Complex I ROS production rates increased with the appearance of diastolic dysfunction (6 weeks of TAC) and remained high thereafter. Surprisingly, maximal ROS production at complex III peaked at 6 weeks of pressure overload. Mitochondrial respiratory capacity (state 3 respiration) was elevated 2 and 6 weeks after TAC, decreased after this point and was significantly impaired at 20 weeks, when contractile function was also impaired and ROS damage was found with increased hydroxynonenal. Treatment with the ROS scavenger α-phenyl-N-tert-butyl nitrone or the uncoupling agent dinitrophenol significantly reduced ROS production rates at 6 weeks. Despite the decline in ROS production capacity, no differences in contractile function between treated and untreated animals were observed. Increased ROS production occurs early in the development of heart failure with a peak at the onset of diastolic dysfunction. However, ROS production may not be related to the onset of contractile dysfunction. PMID:24951621

  8. High Pressure Electrolyzer System Evaluation

    NASA Technical Reports Server (NTRS)

    Prokopius, Kevin; Coloza, Anthony

    2010-01-01

    This report documents the continuing efforts to evaluate the operational state of a high pressure PEM based electrolyzer located at the NASA Glenn Research Center. This electrolyzer is a prototype system built by General Electric and refurbished by Hamilton Standard (now named Hamilton Sunstrand). It is capable of producing hydrogen and oxygen at an output pressure of 3000 psi. The electrolyzer has been in storage for a number of years. Evaluation and testing was performed to determine the state of the electrolyzer and provide an estimate of the cost for refurbishment. Pressure testing was performed using nitrogen gas through the oxygen ports to ascertain the status of the internal membranes and seals. It was determined that the integrity of the electrolyzer stack was good as there were no appreciable leaks in the membranes or seals within the stack. In addition to the integrity testing, an itemized list and part cost estimate was produced for the components of the electrolyzer system. An evaluation of the system s present state and an estimate of the cost to bring it back to operational status was also produced.

  9. An automated pressure data acquisition system for evaluation of pressure sensitive paint chemistries

    NASA Technical Reports Server (NTRS)

    Sealey, Bradley S.; Mitchell, Michael; Burkett, Cecil G.; Oglesby, Donald M.

    1993-01-01

    An automated pressure data acquisition system for testing of pressure sensitive phosphorescent paints was designed, assembled, and tested. The purpose of the calibration system is the evaluation and selection of pressure sensitive paint chemistries that could be used to obtain global aerodynamic pressure distribution measurements. The test apparatus and setup used for pressure sensitive paint characterizations is described. The pressure calibrations, thermal sensitivity effects, and photodegradation properties are discussed.

  10. Evaluation of Acoustic Emission SHM of PRSEUS Composite Pressure Cube Tests

    NASA Technical Reports Server (NTRS)

    Horne, Michael R.; Madaras, Eric I.

    2013-01-01

    A series of tests of the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) pressure cube were conducted during third quarter 2011 at NASA Langley Research Center (LaRC) in the Combined Loads Test facility (COLTS). This is a report of the analysis of the Acoustic Emission (AE) data collected during those tests. The AE signals of the later tests are consistent with the final failure progression through two of the pressure cube panels. Calibration tests and damage precursor AE indications, from preliminary checkout pressurizations, indicated areas of concern that eventually failed. Hence those tests have potential for vehicle health monitoring.

  11. Studies and analyses of the space shuttle main engine: High-pressure oxidizer turbopump failure information propagation model

    NASA Technical Reports Server (NTRS)

    Glover, R. C.; Rudy, S. W.; Tischer, A. E.

    1987-01-01

    The high-pressure oxidizer turbopump (HPOTP) failure information propagation model (FIPM) is presented. The text includes a brief discussion of the FIPM methodology and the various elements which comprise a model. Specific details of the HPOTP FIPM are described. Listings of all the HPOTP data records are included as appendices.

  12. Evaluative pressure overcomes perceptual load effects.

    PubMed

    Normand, Alice; Autin, Frédérique; Croizet, Jean-Claude

    2015-06-01

    Perceptual load has been found to be a powerful bottom-up determinant of distractibility, with high perceptual load preventing distraction by any irrelevant information. However, when under evaluative pressure, individuals exert top-down attentional control by giving greater weight to task-relevant features, making them more distractible from task-relevant distractors. One study tested whether the top-down modulation of attention under evaluative pressure overcomes the beneficial bottom-up effect of high perceptual load on distraction. Using a response-competition task, we replicated previous findings that high levels of perceptual load suppress task-relevant distractor response interference, but only for participants in a control condition. Participants under evaluative pressure (i.e., who believed their intelligence was assessed) showed interference from task-relevant distractor at all levels of perceptual load. This research challenges the assumptions of the perceptual load theory and sheds light on a neglected determinant of distractibility: the self-relevance of the performance situation in which attentional control is solicited.

  13. Design and Evaluation of a Web-Based Symptom Monitoring Tool for Heart Failure.

    PubMed

    Wakefield, Bonnie J; Alexander, Gregory; Dohrmann, Mary; Richardson, James

    2017-05-01

    Heart failure is a chronic condition where symptom recognition and between-visit communication with providers are critical. Patients are encouraged to track disease-specific data, such as weight and shortness of breath. Use of a Web-based tool that facilitates data display in graph form may help patients recognize exacerbations and more easily communicate out-of-range data to clinicians. The purposes of this study were to (1) design a Web-based tool to facilitate symptom monitoring and symptom recognition in patients with chronic heart failure and (2) conduct a usability evaluation of the Web site. Patient participants generally had a positive view of the Web site and indicated it would support recording their health status and communicating with their doctors. Clinician participants generally had a positive view of the Web site and indicated it would be a potentially useful adjunct to electronic health delivery systems. Participants expressed a need to incorporate decision support within the site and wanted to add other data, for example, blood pressure, and have the ability to adjust font size. A few expressed concerns about data privacy and security. Technologies require careful design and testing to ensure they are useful, usable, and safe for patients and do not add to the burden of busy providers.

  14. Early Caffeine Prophylaxis and Risk of Failure of Initial Continuous Positive Airway Pressure in Very Low Birth Weight Infants.

    PubMed

    Patel, Ravi M; Zimmerman, Kanecia; Carlton, David P; Clark, Reese; Benjamin, Daniel K; Smith, P Brian

    2017-11-01

    To test the hypothesis that early caffeine treatment on the day of birth, compared with later treatment in very low birth weight (VLBW, <1500 g) infants receiving continuous positive airway pressure (CPAP) therapy, is associated with a decreased risk of CPAP failure in the first week of life. Multicenter, observational cohort study in 366 US neonatal intensive care units. We evaluated inborn, VLBW infants discharged from 2000 to 2014, who received only CPAP therapy without surfactant treatment on day of life (DOL) 0, had a 5-minute Apgar ≥3, and received caffeine in the first week of life. We used multivariable conditional logistic regression to compare the risk of CPAP failure, defined as invasive mechanical ventilation or surfactant therapy on DOL 1-6, by timing of caffeine treatment as either early (initiation on DOL 0) or routine (initiation on DOL 1-6). We identified 11 133 infants; 4528 (41%) received early caffeine and 6605 (59%) received routine caffeine. Median gestational age was lower in the early caffeine group, 29 weeks (25th, 75th percentiles; 28, 30) vs the routine caffeine group, 30 weeks (29, 31); P < 0.001. The incidence of CPAP failure on DOL 1-6 was similar between the early and routine caffeine groups: 22% vs 21%; adjusted OR = 1.05 (95% CI: 0.93, 1.18). Early caffeine treatment on the day of birth was not associated with a decreased risk of CPAP failure in the first week of life for VLBW infants initially treated with CPAP. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. The errors of metacognitive evaluation on metacognitive failure of students in mathematical problem solving

    NASA Astrophysics Data System (ADS)

    Huda, Nizlel; Sutawidjaja, Akbar; Subanji; Rahardjo, Swasono

    2018-04-01

    Metacognitive activity is very important in mathematical problems solving. Metacognitive activity consists of metacognitive awareness, metacognitive evaluation and metacognitive regulation. This study aimed to reveal the errors of metacognitive evaluation in students’ metacognitive failure in solving mathematical problems. 20 students taken as research subjects were grouped into three groups: the first group was students who experienced one metacognitive failure, the second group was students who experienced two metacognitive failures and the third group was students who experienced three metacognitive failures. One person was taken from each group as the reasearch subject. The research data was collected from worksheets done using think aload then followed by interviewing the research subjects based on the results’ of subject work. The findings in this study were students who experienced metacognitive failure in solving mathematical problems tends to miscalculate metacognitive evaluation in considering the effectiveness and limitations of their thinking and the effectiveness of their chosen strategy of completion.

  16. NASA Prototype All Composite Tank Cryogenic Pressure Tests to Failure with Structural Health Monitoring

    NASA Technical Reports Server (NTRS)

    Werlink, Rudolph J.; Pena, Francisco

    2015-01-01

    This Paper will describe the results of pressurization to failure of 100 gallon composite tanks using liquid nitrogen. Advanced methods of health monitoring will be compared as will the experimental data to a finite element model. The testing is wholly under NASA including unique PZT (Lead Zirconate Titanate) based active vibration technology. Other technologies include fiber optics strain based systems including NASA AFRC technology, Acoustic Emission, Acellent smart sensor, this work is expected to lead to a practical in-Sutu system for composite tanks.

  17. Heart Failure Virtual Consultation: bridging the gap of heart failure care in the community - A mixed-methods evaluation.

    PubMed

    Gallagher, Joseph; James, Stephanie; Keane, Ciara; Fitzgerald, Annie; Travers, Bronagh; Quigley, Etain; Hecht, Christina; Zhou, Shuaiwei; Watson, Chris; Ledwidge, Mark; McDonald, Kenneth

    2017-08-01

    We undertook a mixed-methods evaluation of a Web-based conferencing service (virtual consult) between general practitioners (GPs) and cardiologists in managing patients with heart failure in the community to determine its effect on use of specialist heart failure services and acceptability to GPs. All cases from June 2015 to October 2016 were recorded using a standardized recording template, which recorded patient demographics, medical history, medications, and outcome of the virtual consult for each case. Quantitative surveys and qualitative interviewing of 17 participating GPs were also undertaken. During this time, 142 cases were discussed-68 relating to a new diagnosis of heart failure, 53 relating to emerging deterioration in a known heart failure patient, and 21 relating to therapeutic issues. Only 17% required review in outpatient department following the virtual consultation. GPs reported increased confidence in heart failure management, a broadening of their knowledge base, and a perception of overall better patient outcomes. These data from an initial experience with Heart Failure Virtual Consultation present a very positive impact of this strategy on the provision of heart failure care in the community and acceptability to users. Further research on the implementation and expansion of this strategy is warranted. © 2017 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.

  18. Immunity-based detection, identification, and evaluation of aircraft sub-system failures

    NASA Astrophysics Data System (ADS)

    Moncayo, Hever Y.

    This thesis describes the design, development, and flight-simulation testing of an integrated Artificial Immune System (AIS) for detection, identification, and evaluation of a wide variety of sensor, actuator, propulsion, and structural failures/damages including the prediction of the achievable states and other limitations on performance and handling qualities. The AIS scheme achieves high detection rate and low number of false alarms for all the failure categories considered. Data collected using a motion-based flight simulator are used to define the self for an extended sub-region of the flight envelope. The NASA IFCS F-15 research aircraft model is used and represents a supersonic fighter which include model following adaptive control laws based on non-linear dynamic inversion and artificial neural network augmentation. The flight simulation tests are designed to analyze and demonstrate the performance of the immunity-based aircraft failure detection, identification and evaluation (FDIE) scheme. A general robustness analysis is also presented by determining the achievable limits for a desired performance in the presence of atmospheric perturbations. For the purpose of this work, the integrated AIS scheme is implemented based on three main components. The first component performs the detection when one of the considered failures is present in the system. The second component consists in the identification of the failure category and the classification according to the failed element. During the third phase a general evaluation of the failure is performed with the estimation of the magnitude/severity of the failure and the prediction of its effect on reducing the flight envelope of the aircraft system. Solutions and alternatives to specific design issues of the AIS scheme, such as data clustering and empty space optimization, data fusion and duplication removal, definition of features, dimensionality reduction, and selection of cluster/detector shape are also

  19. Application of a system for measuring foot plantar pressure for evaluation of human mobility

    NASA Astrophysics Data System (ADS)

    Klimiec, Ewa; Jasiewicz, Barbara; Zaraska, Krzysztof; Piekarski, Jacek; Guzdek, Piotr; Kołaszczyński, Grzegorz

    2016-11-01

    The paper presents evaluation of human mobility by gait analysis, carried out in natural conditions (outside laboratory). Foot plantar pressure is measured using a shoe insole with 8 sensors placed in different anatomical zones of the foot, and placed inside a sports footwear. Polarized PVDF foil is used as a sensor material. A wireless transmission system is used to transmit voltage values to the computer. Due to linear relationship between force and transducer voltage, energy released during walking in arbitrary units can be calculated as integral of the square of transducer voltage over time. Gait measurements have been done over the next few days on healthy person during normal walking and slow walking. Performed measurements allow determination of walking speed (number of steps per second), gait rhythm and manner of walking (applying force to inside versus outside part of the sole). It is found that switching from normal to slow walk increases gait energy by 25% while the pressure distribution across the anatomical regions of the foot remains unchanged. The results will be used for developing a programme for evaluation of patients with cardiac failure and future integration of actimetry with pulse and spirometry measurements.

  20. Increased left atrial pressure in non-heart failure patients with subclinical hypothyroidism and atrial fibrillation.

    PubMed

    Sairaku, Akinori; Nakano, Yukiko; Uchimura, Yuko; Tokuyama, Takehito; Kawazoe, Hiroshi; Watanabe, Yoshikazu; Matsumura, Hiroya; Kihara, Yasuki

    2016-05-01

    The impact of subclinical hypothyroidism on the cardiovascular risk is still debated. We aimed to measure the relationship between subclinical hypothyroidism and the left atrial (LA) pressure. The LA pressures and thyroid function were measured in consecutive patients undergoing atrial fibrillation (AF) ablation, who did not have any known heart failure, structural heart disease, or overt thyroid disease. Subclinical hypothyroidism (4.5≤ thyroid-stimulating hormone <19.9 mIU/L) was present in 61 (13.0%) of the 471 patients included. More subclinical hypothyroidism patients than euthyroid patients (55.7% vs 40.2%; P=0.04).'euthyroid patients had persistent or long-standing persistent AF (55.7% vs 40.2%; P = 0.04). The mean LA pressure (10.9 ± 4.7 vs 9.1 ± 4.3 mmHg; P = 0.002) and LA V-wave pressure (17.4 ± 6.5 vs 14.3 ± 5.9 mmHg; P < 0.001) were, respectively, higher in the patients with subclinical hypothyroidism than in the euthyroid patients. After an adjustment for potential confounders, the LA pressures remained significantly higher in the subclinical hypothyroidism patients. A multiple logistic regression model showed that subclinical hypothyroidism was independently associated with a mean LA pressure of >18 mmHg (odds ratio 3.94, 95% CI 1.28 11.2; P = 0.02). Subclinical hypothyroidism may increase the LA pressure in AF patients. © 2016 The authors.

  1. Effects of heat and moisture exchangers on minute ventilation, ventilatory drive, and work of breathing during pressure-support ventilation in acute respiratory failure.

    PubMed

    Pelosi, P; Solca, M; Ravagnan, I; Tubiolo, D; Ferrario, L; Gattinoni, L

    1996-07-01

    To evaluate the effect of two commonly used heat and moisture exchangers on respiratory function and gas exchange in patients with acute respiratory failure during pressure-support ventilation. Prospective, randomized trial. Intensive care unit of a university hospital. Fourteen patients with moderate acute respiratory failure, receiving pressure-support ventilation. Patients were assigned randomly to two treatment groups, in which two different heat and moisture exchangers were used: Hygroster (DAR S.p.A., Mirandola, Italy) with higher deadspace and lower resistance (group 1, n = 7), and Hygrobac-S (DAR S.p.A.) with lower deadspace and higher resistance (group 2, n = 7). Patients were assessed at three pressure-support levels: a) baseline (10.3 +/- 2.4 cm H2O for group 1, 9.3 +/- 1.3 cm H2O for group 2); b) 5 cm H2O above baseline; and c) 5 cm H2O below baseline. Measurements obtained with the heat and moisture exchangers were compared with those values obtained using the standard heated hot water humidifier. At baseline pressure-support ventilation, the insertion of both heat and moisture exchangers induced in all patients a significant increase in the following parameters: minute ventilation (12.4 +/- 3.2 to 15.0 +/- 2.6 L/min for group 1, and 11.8 +/- 3.6 to 14.2 +/- 3.5 L/min for group 2); static intrinsic positive end-expiratory pressure (2.9 +/- 2.0 to 5.1 +/- 3.2 cm H2O for group 1, and 2.9 +/- 1.7 to 5.5 +/- 3.0 cm H2O for group 2); ventilatory drive, expressed as P41 (2.7 +/- 2.0 to 5.2 +/- 4.0 cm H2O for group 1, and 3.3 +/- 2.0 to 5.3 +/- 3.0 cm H2O for group 2); and work of breathing, expressed as either power (8.8 +/- 9.4 to 14.5 +/- 10.3 joule/ min for group 1, and 10.5 +/- 7.4 to 16.6 +/- 11.0 joule/min for group 2) or work per liter of ventilation (0.6 +/- 0.6 to 1.0 +/- 0.7 joule/L for group 1, and 0.8 +/- 0.4 to 1.1 +/- 0.5 joule/L. for group 2). These increases also occurred when pressure-support ventilation was both above and below the baseline

  2. [The effect of positive pressure ventilation combined with diaphragm pacing on respiratory mechanics in patients with respiratory failure].

    PubMed

    Deng, Yi-Jun; Ji, You-Lin; Chen, Lan-Ping; Jin, Qin

    2011-04-01

    To observe the effects of combining positive pressure ventilation with diaphragm pacing on respiratory mechanics in patients with respiratory failure. Twenty patients with central respiratory failure were studied with cohorts. The effects on respiratory mechanics were respectively observed in patients in control group, in whom ventilation by positive pressure only, and patients in experimental group in whom ventilation was instituted by combining positive pressure ventilation with diaphragm pacing. Compared with control group, mean airway pressure (Paw, cm H(2)O, 1 cm H(2)O= 0.098 kPa) and plateau pressure (Pplat, cm H(2)O) were significantly decreased in experimental group (Paw: 6.1±1.3 vs. 7.3±1.8; Pplat: 10.4±2.5 vs. 12.1±2.6, both P<0.05), while the negative value of peak esophageal pressure (P(PEAK ES) , cm H(2)O), the negative value of the difference between peak and basic esophageal pressure (dP(ES), cm H(2)O), transpulmonary pressure at end of inspiration hold (Ptp plat, cm H(2)O ), static compliance (Cst, ml/cm H(2)O) were significantly increased in experimental group (P(PEAK ES): -8.3± 1.9 vs. -3.2±1.4; dP(ES) : -11.2±2.6 vs. -8.2±2.2; Ptp plat: 23.6±3.8 vs. 15.6±3.1; Cst: 52.7±8.2 vs. 48.3±7.2, all P<0.05). No differences were found in airway resistance (Raw, cm H(2)O×L(-1) ×s(-1) ) and lung resistance (R(L), cm H(2)O×L(-1) ×s(-1) ) between experimental group and control group (Raw: 2.1±0.5 vs. 2.3±0.4; R(L): 2.9±0.6 vs. 3.1±0.5, both P>0.05). Work of breath by patient (WOBp, J/L) was significantly increased and work of breath by ventilator (WOBv, J/L) was significantly decreased in experimental group compared with control group (WOBp: 0.18±0.03 vs. 0; WOBv: 0.31±0.07 vs. 0.53±0.11, both P<0.05). Compared with positive pressure ventilation , positive pressure ventilation combined with diaphragm pacing can decrease the Paw, increase intrathoracic negative pressure, transpulmonary pressure, and Cst, and decrease WOBv, while there is

  3. Design and evaluation of candidate pressure ports for the HYFLITE experiment

    NASA Technical Reports Server (NTRS)

    Teter, John E., Jr.; Cleckner, Craig S.; Vontheumer, Alfred E.

    1994-01-01

    A concept for placing a pressure transducer directly in a shuttle type tile was developed at Langley Research Center. A 5 inch long quartz with a .020 inch inner diameter provides the thermal isolation necessary to allow 2800 F surface pressure measurements to be taken by pressure transducer rated at 250 F. The assembly is potted in place with RTV 560 in a piece of FRCI-12 thermal protection system insulation tile. The integrity of the thermal protection system is maintained even with the intrusion of the pressure port assembly and the pressure port does not disrupt the air flow across the lifting body. Approximately 200 of these pressure ports are to be used in each of the Hypersonic Flight Experiment (HYFLITE) flight tests. Initial vibroacoustic and aerothermal testing of the pressure port designs have been completed at Langley Research vibration laboratory and the 20 MWatt 2 x 9 turbulent duct facility at Ames Research Center. The performance of the pressure ports were found to be well within the required design limits for all cases. In addition, a failure mode in which the entire pressure port assembly was removed proved to be a begin case.

  4. Effects of short-term continuous positive airway pressure on myocardial sympathetic nerve function and energetics in patients with heart failure and obstructive sleep apnea: a randomized study.

    PubMed

    Hall, Allison B; Ziadi, Maria C; Leech, Judith A; Chen, Shin-Yee; Burwash, Ian G; Renaud, Jennifer; deKemp, Robert A; Haddad, Haissam; Mielniczuk, Lisa M; Yoshinaga, Keiichiro; Guo, Ann; Chen, Li; Walter, Olga; Garrard, Linda; DaSilva, Jean N; Floras, John S; Beanlands, Rob S B

    2014-09-09

    Heart failure with reduced ejection fraction and obstructive sleep apnea (OSA), 2 states of increased metabolic demand and sympathetic nervous system activation, often coexist. Continuous positive airway pressure (CPAP), which alleviates OSA, can improve ventricular function. It is unknown whether this is due to altered oxidative metabolism or presynaptic sympathetic nerve function. We hypothesized that short-term (6-8 weeks) CPAP in patients with OSA and heart failure with reduced ejection fraction would improve myocardial sympathetic nerve function and energetics. Forty-five patients with OSA and heart failure with reduced ejection fraction (left ventricular ejection fraction 35.8±9.7% [mean±SD]) were evaluated with the use of echocardiography and 11C-acetate and 11C-hydroxyephedrine positron emission tomography before and ≈6 to 8 weeks after randomization to receive short-term CPAP (n=22) or no CPAP (n=23). Work metabolic index, an estimate of myocardial efficiency, was calculated as follows: (stroke volume index×heart rate×systolic blood pressure÷Kmono), where Kmono is the monoexponential function fit to the myocardial 11C-acetate time-activity data, reflecting oxidative metabolism. Presynaptic sympathetic nerve function was measured with the use of the 11C-hydroxyephedrine retention index. CPAP significantly increased hydroxyephedrine retention versus no CPAP (Δretention: +0.012 [0.002, 0.021] versus -0.006 [-0.013, 0.005] min(-1); P=0.003). There was no significant change in work metabolic index between groups. However, in those with more severe OSA (apnea-hypopnea index>20 events per hour), CPAP significantly increased both work metabolic index and systolic blood pressure (P<0.05). In patients with heart failure with reduced ejection fraction and OSA, short-term CPAP increased hydroxyephedrine retention, indicating improved myocardial sympathetic nerve function, but overall did not affect energetics. In those with more severe OSA, CPAP may improve

  5. Sleep in heart failure.

    PubMed

    Naughton, Matthew T; Lorenzi-Filho, Geraldo

    2009-01-01

    Sleep plays a large role in patients with heart failure. In normal subjects, sleep is usually in a supine position with reduced sympathetic drive, elevated vagal tone and as such a relatively lower cardiac output and minute ventilation, allowing for recuperation. Patients with heart failure may not experience the same degree of autonomic activity change and the supine position may place a large strain on the pulmonary system. More than half of all heart failure patients have one of two types of sleep apnea: either obstructive or central sleep apnea. Some patients have both types. Obstructive sleep apnea is likely to be a cause of heart failure due to large negative intrathoracic pressures, apnea related hypoxemia and hypercapnia, terminated by an arousal and surge in systemic blood pressure associated with endothelial damage and resultant premature atherosclerosis. Reversal of obstructive sleep apnea improves blood pressure, systolic contraction and autonomic dysfunction however mortality studies are lacking. Central sleep apnea with Cheyne Stokes pattern of respiration (CSA-CSR) occurs as a result of increased central controller (brainstem driving ventilation) and plant (ventilation driving CO2) gain in the setting of a delayed feed back (i.e., low cardiac output). It is thought this type of apnea is a result of moderately to severely impaired cardiac function and is possibly indicative of high mortality. Treatment of CSA-CSR is best undertaken by treating the underlying cardiac condition which may include with medications, pacemakers, transplantation or continuous positive airway pressure (CPAP). In such patients CPAP exerts unique effects to assist cardiac function and reduce pulmonary edema. Whether CPAP improves survival in this heart failure population remains to be determined.

  6. Benchtop evaluation of pressure barrier insufflator and standard insufflator systems.

    PubMed

    Nepple, Kenneth G; Kallogjeri, Dorina; Bhayani, Sam B

    2013-01-01

    Previous experimental research has reported minimal differences in pressure maintenance between different versions of standard insufflators (SI). However, a recent report identified potential clinical benefits with a valveless pressure barrier insufflator (PBI). We sought to perform a benchtop objective evaluation of SI and PBI systems. A rigid box system with continuous pressure manometry was used to evaluate a PBI (Surgiquest Airseal) and two SIs (SI1 = Stryker PneumoSure High Flow Insufflator and SI2 = Storz SCB Thermoflator). Pressure maintenance of 15 mmHg was evaluated during experimental conditions of leakage from a 5 mm port site, leakage from a 12 mm port site, and continuous suction. With leakage from the 5 mm port site, the PBI maintained pressure of >13 mmHg whereas the pressures dropped moderately with the SI1 (7-13 mmHg) and SI2 insufflators (3-7 mmHg) and did not regain goal pressure until leakage was stopped. With leakage from 12 mm port site, the PBI pressure decreased to 9-11 mmHg, whereas the SI1 and SI2 lost insufflation pressures completely. The PBI maintained pressure of >11 mmHg during continuous suction while the SI1 and SI2 lost pressure entirely, and actually showed negative pressure from air suction into the rigid box system. When evaluated statistically with the mixed model repeated measures ANOVA, the SI1 and SI2 performed similarly while the PBI maintained increased pressure. In the experimental rigid box system, the PBI more successfully maintained pressure in response to leakage and suction than SIs.

  7. Is there a place for intra-aortic balloon counterpulsation support in acute right ventricular failure by pressure-overload?

    PubMed

    Vanden Eynden, Frederic; Mets, Gilles; De Somer, Filip; Bouchez, Stefaan; Bove, Thierry

    2015-10-15

    Most therapeutic strategies for acute right ventricular failure (RVF) by pressure-overload are directed to improve cardiac output and coronary perfusion pressure by vasopressive agents. The eventual role of intra-aortic balloon counterpulsation (IABP) support remains questionable. This study investigates the contribution of IABP for acute RVF by pressure-overload, in comparison with phenylephrine (PE) and norepinephrine (NOR). Acute RVF is induced by fixed pulmonary artery constriction in 6 pigs, pursuing a 50% reduction of cardiac output. Assessment of the treatment interventions included biventricular PV-loop analysis, and continuous measurement of aortic and right coronary artery flow. Restoration of baseline cardiac output was only observed by administration of NOR (Baseline=3.82±1.52ml/min - RVF=2.03±0.59ml/min - IABP=2.45±0.62ml/min - PE=2.98±0.63ml/min - NOR=3.95±0.73ml/min, p<0.001). NOR had most effect on biventricular contractility (PRSW-slope-RV: IABP +24% - PE +59% - NOR +208%, p<0.001 and PRSW-slope-LV: IABP +36% - PE +53% - NOR +196%, p<0.001), heart rate acceleration (IABP +7% - PE +12% - NOR +51%, p<0.001), and RCA flow (IABP +31% - PE +58% - NOR +180%, p<0.001), concomitant to a higher increase of LV-to-RV pressure ratio (IABP: +7% versus -3%, PE: +36% versus +8%, NOR: +101% versus 42%). The hemodynamic contribution of IABP was limited, unless a modest improvement of LV compliance during PE and NOR infusion. In a model of acute pressure-overload RV failure, IABP appears to offer limited hemodynamic benefit. The administration of norepinephrine is most effective to correct systemic output and myocardial perfusion through adding an inotropic and chronotropic effect to systemic vasopression. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. Evaluation of a Multi-Axial, Temperature, and Time Dependent (MATT) Failure Model

    NASA Technical Reports Server (NTRS)

    Richardson, D. E.; Anderson, G. L.; Macon, D. J.; Rudolphi, Michael (Technical Monitor)

    2002-01-01

    To obtain a better understanding the response of the structural adhesives used in the Space Shuttle's Reusable Solid Rocket Motor (RSRM) nozzle, an extensive effort has been conducted to characterize in detail the failure properties of these adhesives. This effort involved the development of a failure model that includes the effects of multi-axial loading, temperature, and time. An understanding of the effects of these parameters on the failure of the adhesive is crucial to the understanding and prediction of the safety of the RSRM nozzle. This paper documents the use of this newly developed multi-axial, temperature, and time (MATT) dependent failure model for modeling failure for the adhesives TIGA 321, EA913NA, and EA946. The development of the mathematical failure model using constant load rate normal and shear test data is presented. Verification of the accuracy of the failure model is shown through comparisons between predictions and measured creep and multi-axial failure data. The verification indicates that the failure model performs well for a wide range of conditions (loading, temperature, and time) for the three adhesives. The failure criterion is shown to be accurate through the glass transition for the adhesive EA946. Though this failure model has been developed and evaluated with adhesives, the concepts are applicable for other isotropic materials.

  9. Bed failure induced by internal solitary waves

    NASA Astrophysics Data System (ADS)

    Rivera-Rosario, Gustavo A.; Diamessis, Peter J.; Jenkins, James T.

    2017-07-01

    The pressure field inside a porous bed induced by the passage of an Internal Solitary Wave (ISW) of depression is examined using high-accuracy numerical simulations. The velocity and density fields are obtained by solving the Dubreil-Jacotin-Long Equation, for a two-layer, continuously stratified water column. The total wave-induced pressure across the surface of the bed is computed by vertically integrating for the hydrostatic and nonhydrostatic contributions. The bed is assumed to be a continuum composed of either sand or silt, with a small amount of trapped gas. Results show variations in pore-water pressure penetrating deeper into more conductive materials and remaining for a prolonged period after the wave has passed. In order to quantify the potential for failure, the vertical pressure gradient is compared against the buoyant weight of the bed. The pressure gradient exceeds this weight for weakly conductive materials. Failure is further enhanced by a decrease in bed saturation, consistent with studies in surface-wave induced failure. In deeper water, the ISW-induced pressure is stronger, causing failure only for weakly conductive materials. The pressure associated with the free-surface displacement that accompanies ISWs is significant, when the water depth is less than 100 m, but has little influence when it is greater than 100 m, where the hydrostatic pressure due to the pycnocline displacement is much larger. Since the pore-pressure gradient reduces the specific weight of the bed, results show that particles are easier for the flow to suspend, suggesting that pressure contributes to the powerful resuspension events observed in the field.

  10. Role of heat shock transcription factor 1(HSF1)-upregulated macrophage in ameliorating pressure overload-induced heart failure in mice.

    PubMed

    Du, Peizhao; Chang, Yaowei; Dai, Fangjie; Wei, Chunyan; Zhang, Qi; Li, Jiming

    2018-08-15

    In order to explore the role of macrophages in HSF1-mediated alleviation of heart failure, mice model of pressure overload-induced heart failure was established using transverse aortic constriction (TAC). Changes in cardiac function and morphology were studied in TAC and SHAM groups using ultrasonic device, tissue staining, electron microscopy, real-time quantitative polymerase chain reaction (RT-QPCR), and Western blotting. We found that mice in the TAC group showed evidence of impaired cardiac function and aggravation of fibrosis on ultrasonic and histopathological examination when compared to those in the SHAM group. The expressions of HSF1, LC3II/LC3I, Becline-1 and HIF-1, as well as autophagosome formation in TAC group were greater than that in SHAM group. On sub-group analyses in the TAC group, improved cardiac function and alleviation of fibrosis was observed in the HSF1 TG subgroup as compared to that in the wild type subgroup. Expressions of LC3II/LC3I, Becline-1 and HIF-1, too showed an obvious increase; and increased autophagosome formation was observed on electron microscopy. Opposite results were observed in the HSF1 KO subgroup. These results collectively suggest that in the pressure overload heart failure model, HSF1 promoted formation of macrophages by inducing upregulation of HIF-1 expression, through which heart failure was ameliorated. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Process evaluation of a cluster-randomised trial testing a pressure ulcer prevention care bundle: a mixed-methods study.

    PubMed

    Roberts, Shelley; McInnes, Elizabeth; Bucknall, Tracey; Wallis, Marianne; Banks, Merrilyn; Chaboyer, Wendy

    2017-02-13

    As pressure ulcers contribute to significant patient burden and increased health care costs, their prevention is a clinical priority. Our team developed and tested a complex intervention, a pressure ulcer prevention care bundle promoting patient participation in care, in a cluster-randomised trial. The UK Medical Research Council recommends process evaluation of complex interventions to provide insight into why they work or fail and how they might be improved. This study aimed to evaluate processes underpinning implementation of the intervention and explore end-users' perceptions of it, in order to give a deeper understanding of its effects. A pre-specified, mixed-methods process evaluation was conducted as an adjunct to the main trial, guided by a framework for process evaluation of cluster-randomised trials. Data was collected across eight Australian hospitals but mainly focused on the four intervention hospitals. Quantitative and qualitative data were collected across the evaluation domains: recruitment, reach, intervention delivery and response to intervention, at both cluster and individual patient level. Quantitative data were analysed using descriptive and inferential statistics. Qualitative data were analysed using thematic analysis. In the context of the main trial, which found a 42% reduction in risk of pressure ulcer with the intervention that was not significant after adjusting for clustering and covariates, this process evaluation provides important insights. Recruitment and reach among clusters and individuals was high, indicating that patients, nurses and hospitals are willing to engage with a pressure ulcer prevention care bundle. Of 799 intervention patients in the trial, 96.7% received the intervention, which took under 10 min to deliver. Patients and nurses accepted the care bundle, recognising benefits to it and describing how it enabled participation in pressure ulcer prevention (PUP) care. This process evaluation found no major failures

  12. Optical zero-differential pressure switch and its evaluation in a multiple pressure measuring system

    NASA Technical Reports Server (NTRS)

    Powell, J. A.

    1977-01-01

    The design of a clamped-diaphragm pressure switch is described in which diaphragm motion is detected by a simple fiber-optic displacement sensor. The switch was evaluated in a pressure measurement system where it detected the zero crossing of the differential pressure between a static test pressure and a tank pressure that was periodically ramped from near zero to fullscale gage pressure. With a ramping frequency of 1 hertz and a full-scale tank pressure of 69 N/sq cm gage (100 psig), the switch delay was as long as 2 milliseconds. Pressure measurement accuracies were 0.25 to 0.75 percent of full scale. Factors affecting switch performance are also discussed.

  13. Burst pressure investigation of filament wound type IV composite pressure vessel

    NASA Astrophysics Data System (ADS)

    Farhood, Naseer H.; Karuppanan, Saravanan; Ya, H. H.; Baharom, Mohamad Ariff

    2017-12-01

    Currently, composite pressure vessels (PVs) are employed in many industries such as aerospace, transportations, medical etc. Basically, the use of PVs in automotive application as a compressed natural gas (CNG) storage cylinder has been growing rapidly. Burst failure due to the laminate failure is the most critical failure mechanism for composite pressure vessels. It is predominantly caused by excessive internal pressure due to an overfilling or an overheating. In order to reduce fabrication difficulties and increase the structural efficiency, researches and studies are conducted continuously towards the proper selection of vessel design parameters. Hence, this paper is focused on the prediction of first ply failure pressure for such vessels utilizing finite element simulation based on Tsai-Wu and maximum stress failure criterions. The effects of laminate stacking sequence and orientation angle on the burst pressure were investigated in this work for a constant layered thickness PV. Two types of winding design, A [90°2/∓θ16/90°2] and B [90°2/∓θ]ns with different orientations of helical winding reinforcement were analyzed for carbon/epoxy composite material. It was found that laminate A sustained a maximum burst pressure of 55 MPa for a sequence of [90°2/∓15°16/90°2] while the laminate B returned a maximum burst pressure of 45 MPa corresponding to a stacking sequence of [90°2/±15°/90°2/±15°/90°2/±15° ....] up to 20 layers for a constant vessel thickness. For verification, a comparison was done with the literature under similar conditions of analysis and good agreement was achieved with a maximum difference of 4% and 10% for symmetrical and unsymmetrical layout, respectively.

  14. Maternal and neonatal outcomes of respiratory failure during pregnancy.

    PubMed

    Hung, Chen-Yiu; Hu, Han-Chung; Chiu, Li-Chung; Chang, Chih-Hao; Li, Li-Fu; Huang, Chung-Chi; Kao, Chuan-Chi; Cheng, Po-Jen; Kao, Kuo-Chin

    2018-05-01

    Obstetric patients comprise a limited portion of intensive care unit patients, but they often present with unfamiliar conditions and exhibit the potential for catastrophic deterioration. This study evaluated the maternal and neonatal outcomes of respiratory failure during pregnancy. Information on 71 patients at >25 weeks gestation in the ICU with respiratory failure was recorded between 2009 and 2013. The characteristics and outcomes of mothers and fetuses were determined through a retrospective chart review and evaluated using Student's t test, chi-square test, and Fisher's exact test. The leading causes of respiratory failure were postpartum hemorrhage and severe preeclampsia in the obstetric causes group and pneumonia in the nonobstetric causes group during pregnancy and the peripartum period. The non-obstetric causes group exhibited a higher incidence of acute respiratory distress syndrome and renal replacement therapy as well as requiring more ventilator days. The patients in the obstetric causes group showed significant improvement after delivery in the partial pressure of arterial oxygen to the fraction of inspired oxygen and peak inspiratory pressure decrease. Both groups exhibited high incidences of neonatal respiratory distress syndrome. Neonatal complications resulting from meconium aspiration syndrome (MAS) and sepsis were more common in the non-obstetric causes group; however, neurological development impairment was more common in the obstetric causes group. Obstetric cause was associated with longer ventilator free days and fewer episodes of ARDS after delivery. Neonatal complications resulting from different etiologies of respiratory failure were found to differ. Copyright © 2017. Published by Elsevier B.V.

  15. Shunting for hydrocephalus: analysis of techniques and failure patterns.

    PubMed

    Nigim, Fares; Critchlow, Jonathan F; Schneider, Benjamin E; Chen, Clark; Kasper, Ekkehard M

    2014-09-01

    Hydrocephalus is characterized by ventricular dilatation because of progressive accumulation of cerebrospinal fluid. Normal pressure hydrocephalus (NPH) affects a subset of patients representing a reversible clinical triad of gait disturbance, urinary incontinence, and dementia with normal cerebrospinal fluid pressure and composition. Various shunting procedures have been used for treatment, but techniques and outcomes remain under debate. The objective of this study was to evaluate the clinical outcomes of 232 patients with and without NPH after the first-time Ventriculoperitoneal shunt placement and assessed patterns of failure between December 2004 and December 2012. Mean age was 54.7 y in non-NPH and 71.9 y in NPH patients. We used open technique in 34.3% and laparoscopic technique in 65.7% of NPH patients and 32.7% and 67.3% of the non-NPH patients, respectively. A total of 36 of 232 patients displayed shunt failure, 16.4% in NPH and 15.2% in non-NPH patients. Twenty-three of 155 patients failed after laparoscopic and 13 of 77 failed after open placement. Proximal shunt failure was more frequent in the non-NPH cohort. Distal failures accounted for 13 of 232 cases, and the difference between laparoscopic (six of 155) and open failures (seven of 77) was profound, but not between NPH- and non-NPH patients. Shunt failures are related to the placement method. Non-NPH patients showed more proximal failures. NPH patients showed fewer proximal failures. Less distal failures were observed after laparoscopic ventriculoperitoneal shunt placement without significant differences between NPH and non-NPH patients. Beyond this, laparoscopic surgery carries distinct advantages such as shorter operating room times and hospital stays, which should translate into less use of pain medications, earlier mobilization, and a lower incidence of ileus. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Preventing Continuous Positive Airway Pressure Failure: Evidence-Based and Physiologically Sound Practices from Delivery Room to the Neonatal Intensive Care Unit.

    PubMed

    Wright, Clyde J; Sherlock, Laurie G; Sahni, Rakesh; Polin, Richard A

    2018-06-01

    Routine use of continuous positive airway pressure (CPAP) to support preterm infants with respiratory distress is an evidenced-based strategy to decrease incidence of bronchopulmonary dysplasia. However, rates of CPAP failure remain unacceptably high in very premature neonates, who are at high risk for developing bronchopulmonary dysplasia. Using the GRADE framework to assess the quality of available evidence, this article reviews strategies aimed at decreasing CPAP failure, starting with delivery room interventions and followed through to system-based efforts in the neonatal intensive care unit. Despite best efforts, some very premature neonates fail CPAP. Also reviewed are predictors of CPAP failure in this vulnerable population. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Evaluation of lightweight material concepts for aircraft turbine engine rotor failure protection

    DOT National Transportation Integrated Search

    1997-07-01

    Results of the evaluation of lightweight materials for aircraft turbine engine rotor failure protection are presented in this report. The program consisted of two phases. Phase 1 was an evaluation of a group of composite materials which could possibl...

  18. Ultrasonic Nondestructive Evaluation of PRSEUS Pressure Cube Article in Support of Load Test to Failure

    NASA Technical Reports Server (NTRS)

    Johnston, Patrick H.

    2013-01-01

    The PRSEUS Pressure Cube Test was a joint development effort between the Boeing Company and NASA Langley Research Center, sponsored in part by the Environmentally Responsible Aviation Project and Boeing internal R&D. This Technical Memorandum presents the results of ultrasonic inspections in support of the PRSEUS Pressure Cube Test, and is a companion document with the NASA test report and a report on the acoustic emission measurements made during the test.

  19. High Pressure Hydrogen Pressure Relief Devices: Accelerated Life Testing and Application Best Practices

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burgess, Robert M.; Post, Matthew B.; Buttner, William J.

    Pressure relief devices (PRDs ) are used to protect high pressure systems from burst failure caused by overpressurization. Codes and standards require the use of PRDs for the safe design of many pressurized systems. These systems require high reliability due to the risks associated with a burst failure. Hydrogen service can increase the risk of PRD failure due to material property degradation caused by hydrogen attack. The National Renewable Energy Laboratory (NREL) has conducted an accelerated life test on a conventional spring loaded PRD. Based on previous failures in the field, the nozzles specific to these PRDs are of particularmore » interest. A nozzle in a PRD is a small part that directs the flow of fluid toward the sealing surface to maintain the open state of the valve once the spring force is overcome. The nozzle in this specific PRD is subjected to the full tensile force of the fluid pressure. These nozzles are made from 440C material, which is a type of hardened steel that is commonly chosen for high pressure applications because of its high strength properties. In a hydrogen environment, however, 440C is considered a worst case material since hydrogen attack results in a loss of almost all ductility and thus 440C is prone to fatigue and material failure. Accordingly, 440C is not recommended for hydrogen service. Conducting an accelerated life test on a PRD with 440C material provides information on necessary and sufficient conditions required to produce crack initiation and failure. The accelerated life test also provides information on other PRD failure modes that are somewhat statistically random in nature.« less

  20. Kidney (Renal) Failure

    MedlinePlus

    ... News Physician Resources Professions Site Index A-Z Kidney Failure Kidney failure, also known as renal failure, ... evaluated? How is kidney failure treated? What is kidney (renal) failure? The kidneys are designed to maintain ...

  1. Extracellular high-mobility group box 1 mediates pressure overload-induced cardiac hypertrophy and heart failure.

    PubMed

    Zhang, Lei; Liu, Ming; Jiang, Hong; Yu, Ying; Yu, Peng; Tong, Rui; Wu, Jian; Zhang, Shuning; Yao, Kang; Zou, Yunzeng; Ge, Junbo

    2016-03-01

    Inflammation plays a key role in pressure overload-induced cardiac hypertrophy and heart failure, but the mechanisms have not been fully elucidated. High-mobility group box 1 (HMGB1), which is increased in myocardium under pressure overload, may be involved in pressure overload-induced cardiac injury. The objectives of this study are to determine the role of HMGB1 in cardiac hypertrophy and cardiac dysfunction under pressure overload. Pressure overload was imposed on the heart of male wild-type mice by transverse aortic constriction (TAC), while recombinant HMGB1, HMGB1 box A (a competitive antagonist of HMGB1) or PBS was injected into the LV wall. Moreover, cardiac myocytes were cultured and given sustained mechanical stress. Transthoracic echocardiography was performed after the operation and sections for histological analyses were generated from paraffin-embedded hearts. Relevant proteins and genes were detected. Cardiac HMGB1 expression was increased after TAC, which was accompanied by its translocation from nucleus to both cytoplasm and intercellular space. Exogenous HMGB1 aggravated TAC-induced cardiac hypertrophy and cardiac dysfunction, as demonstrated by echocardiographic analyses, histological analyses and foetal cardiac genes detection. Nevertheless, the aforementioned pathological change induced by TAC could partially be reversed by HMGB1 inhibition. Consistent with the in vivo observations, mechanical stress evoked the release and synthesis of HMGB1 in cultured cardiac myocytes. This study indicates that the activated and up-regulated HMGB1 in myocardium, which might partially be derived from cardiac myocytes under pressure overload, may be of crucial importance in pressure overload-induced cardiac hypertrophy and cardiac dysfunction. © 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  2. Development and psychometric evaluation of the Thirst Distress Scale for patients with heart failure.

    PubMed

    Waldréus, Nana; Jaarsma, Tiny; van der Wal, Martje Hl; Kato, Naoko P

    2018-03-01

    Patients with heart failure can experience thirst distress. However, there is no instrument to measure this in patients with heart failure. The aim of the present study was to develop the Thirst Distress Scale for patients with Heart Failure (TDS-HF) and to evaluate psychometric properties of the scale. The TDS-HF was developed to measure thirst distress in patients with heart failure. Face and content validity was confirmed using expert panels including patients and healthcare professionals. Data on the TDS-HF was collected from patients with heart failure at outpatient heart failure clinics and hospitals in Sweden, the Netherlands and Japan. Psychometric properties were evaluated using data from 256 heart failure patients (age 72±11 years). Concurrent validity of the scale was assessed using a thirst intensity visual analogue scale. Patients did not have any difficulties answering the questions, and time taken to answer the questions was about five minutes. Factor analysis of the scale showed one factor. After psychometric testing, one item was deleted. For the eight item TDS-HF, a single factor explained 61% of the variance and Cronbach's alpha was 0.90. The eight item TDS-HF was significantly associated with the thirst intensity score ( r=0.55, p<0.001). Regarding test-retest reliability, the intraclass correlation coefficient was 0.88, and the weighted kappa values ranged from 0.29-0.60. The eight-item TDS-HF is valid and reliable for measuring thirst distress in patients with heart failure.

  3. The importance of integrated left atrial evaluation: From hypertension to heart failure with preserved ejection fraction.

    PubMed

    Beltrami, Matteo; Palazzuoli, Alberto; Padeletti, Luigi; Cerbai, Elisabetta; Coiro, Stefano; Emdin, Michele; Marcucci, Rossella; Morrone, Doralisa; Cameli, Matteo; Savino, Ketty; Pedrinelli, Roberto; Ambrosio, Giuseppe

    2018-02-01

    Functional analysis and measurement of left atrium are an integral part of cardiac evaluation, and they represent a key element during non-invasive analysis of diastolic function in patients with hypertension (HT) and/or heart failure with preserved ejection fraction (HFpEF). However, diastolic dysfunction remains quite elusive regarding classification, and atrial size and function are two key factors for left ventricular (LV) filling evaluation. Chronic left atrial (LA) remodelling is the final step of chronic intra-cavitary pressure overload, and it accompanies increased neurohormonal, proarrhythmic and prothrombotic activities. In this systematic review, we aim to purpose a multi-modality approach for LA geometry and function analysis, which integrates diastolic flow with LA characteristics and remodelling through application of both traditional and new diagnostic tools. The most important studies published in the literature on LA size, function and diastolic dysfunction in patients with HFpEF, HT and/or atrial fibrillation (AF) are considered and discussed. In HFpEF and HT, pulsed and tissue Doppler assessments are useful tools to estimate LV filling pressure, atrio-ventricular coupling and LV relaxation but they need to be enriched with LA evaluation in terms of morphology and function. An integrated evaluation should be also applied to patients with a high arrhythmic risk, in whom eccentric LA remodelling and higher LA stiffness are associated with a greater AF risk. Evaluation of LA size, volume, function and structure are mandatory in the management of patients with HT, HFpEF and AF. A multi-modality approach could provide additional information, identifying subjects with more severe LA remodelling. Left atrium assessment deserves an accurate study inside the cardiac imaging approach and optimised measurement with established cut-offs need to be better recognised through multicenter studies. © 2017 John Wiley & Sons Ltd.

  4. Advanced detection, isolation and accommodation of sensor failures: Real-time evaluation

    NASA Technical Reports Server (NTRS)

    Merrill, Walter C.; Delaat, John C.; Bruton, William M.

    1987-01-01

    The objective of the Advanced Detection, Isolation, and Accommodation (ADIA) Program is to improve the overall demonstrated reliability of digital electronic control systems for turbine engines by using analytical redundacy to detect sensor failures. The results of a real time hybrid computer evaluation of the ADIA algorithm are presented. Minimum detectable levels of sensor failures for an F100 engine control system are determined. Also included are details about the microprocessor implementation of the algorithm as well as a description of the algorithm itself.

  5. Improvement of Heart Failure by Human Amniotic Mesenchymal Stromal Cell Transplantation in Rats.

    PubMed

    Razavi Tousi, Seyed Mohammad Taghi; Faghihi, Mahdieh; Nobakht, Maliheh; Molazem, Mohammad; Kalantari, Elham; Darbandi Azar, Amir; Aboutaleb, Nahid

    2016-07-06

    Background: Recently, stem cells have been considered for the treatment of heart diseases, but no marked improvement has been recorded. This is the first study to examine the functional and histological effects of the transplantation of human amniotic mesenchymal stromal cells (hAMSCs) in rats with heart failure (HF). Methods: This study was conducted in the years 2014 and 2015. 35 male Wistar rats were randomly assigned into 5 equal experimental groups (7 rats each) as 1- Control 2- Heart Failure (HF) 3- Sham 4- Culture media 5- Stem Cell Transplantation (SCT). Heart failure was induced using 170 mg/kg/d of isoproterenol subcutaneously injection in 4 consecutive days. The failure confirmed by the rat cardiac echocardiography on day 28. In SCT group, 3×10 6 cells in 150 µl of culture media were transplanted to the myocardium. At the end, echocardiographic and hemodynamic parameters together with histological evaluation were done. Results: Echocardiography results showed that cardiac ejection fraction in HF group increased from 58/73 ± 9% to 81/25 ± 6/05% in SCT group (p value < 0.001). Fraction shortening in HF group was increased from 27/53 ± 8/58% into 45/55 ± 6/91% in SCT group (p value < 0.001). Furthermore, hAMSCs therapy significantly improved mean diastolic blood pressure, mean arterial pressure, left ventricular systolic pressure, rate pressure product, and left ventricular end-diastolic pressure compared to those in the HF group, with the values reaching the normal levels in the control group. A marked reduction in fibrosis tissue was also found in the SCT group (p value < 0.001) compared with the animals in the HF group. Conclusion: The transplantation of hAMSCs in rats with heart failure not only decreased the level of fibrosis but also conferred significant improvement in heart performance in terms of echocardiographic and hemodynamic parameters.

  6. Failure detection and fault management techniques for flush airdata sensing systems

    NASA Technical Reports Server (NTRS)

    Whitmore, Stephen A.; Moes, Timothy R.; Leondes, Cornelius T.

    1992-01-01

    A high-angle-of-attack flush airdata sensing system was installed and flight tested on the F-18 High Alpha Research Vehicle at NASA-Dryden. This system uses a matrix of pressure orifices arranged in concentric circles on the nose of the vehicle to determine angles of attack, angles of sideslip, dynamic pressure, and static pressure as well as other airdata parameters. Results presented use an arrangement of 11 symmetrically distributed ports on the aircraft nose. Experience with this sensing system data indicates that the primary concern for real-time implementation is the detection and management of overall system and individual pressure sensor failures. The multiple port sensing system is more tolerant to small disturbances in the measured pressure data than conventional probe-based intrusive airdata systems. However, under adverse circumstances, large undetected failures in individual pressure ports can result in algorithm divergence and catastrophic failure of the entire system. How system and individual port failures may be detected using chi sq. analysis is shown. Once identified, the effects of failures are eliminated using weighted least squares.

  7. Response of Preterm Infants to 2 Noninvasive Ventilatory Support Systems: Nasal CPAP and Nasal Intermittent Positive-Pressure Ventilation.

    PubMed

    Silveira, Carmen Salum Thomé; Leonardi, Kamila Maia; Melo, Ana Paula Carvalho Freire; Zaia, José Eduardo; Brunherotti, Marisa Afonso Andrade

    2015-12-01

    Noninvasive ventilation (NIV) in preterm infants is currently applied using intermittent positive pressure (2 positive-pressure levels) or in a conventional manner (one pressure level). However, there are no studies in the literature comparing the chances of failure of these NIV methods. The aim of this study was to evaluate the occurrence of failure of 2 noninvasive ventilatory support systems in preterm neonates over a period of 48 h. A randomized, prospective, clinical study was conducted on 80 newborns (gestational age < 37 weeks, birthweight < 2,500 g). The infants were randomized into 2 groups: 40 infants were treated with nasal CPAP and 40 infants with nasal intermittent positive-pressure ventilation (NIPPV). The occurrence of apnea, progression of respiratory distress, nose bleeding, and agitation was defined as ventilation failure. The need for intubation and re-intubation after failure was also observed. There were no significant differences in birth characteristics between groups. Ventilatory support failure was observed in 25 (62.5%) newborns treated with nasal CPAP and in 12 (30%) newborns treated with NIPPV, indicating an association between NIV failure and the absence of intermittent positive pressure (odds ratio [OR] 1.22, P < .05). Apnea (32.5%) was the main reason for nasal CPAP failure. After failure, 25% (OR 0.33) of the newborns receiving nasal CPAP and 12.5% (OR 0.14) receiving NIPPV required invasive mechanical ventilation. Ventilatory support failure was significantly more frequent when nasal CPAP was used. Copyright © 2015 by Daedalus Enterprises.

  8. The effects of pressure dependent constitutive model to simulate concrete structures failure under impact loads

    NASA Astrophysics Data System (ADS)

    Mokhatar, S. N.; Sonoda, Y.; Kamarudin, A. F.; Noh, M. S. Md; Tokumaru, S.

    2018-04-01

    The main objective of this paper is to explore the effect of confining pressure in the compression and tension zone by simulating the behaviour of reinforced concrete/mortar structures subjected to the impact load. The analysis comprises the numerical simulation of the influences of high mass low speed impact weight dropping on concrete structures, where the analyses are incorporated with meshless method namely as Smoothed Particle Hydrodynamics (SPH) method. The derivation of the plastic stiffness matrix of Drucker-Prager (DP) that extended from Von-Mises (VM) yield criteria to simulate the concrete behaviour were presented in this paper. In which, the displacements for concrete/mortar structures are assumed to be infinitesimal. Furthermore, the influence of the different material model of DP and VM that used numerically for concrete and mortar structures are also discussed. Validation upon existing experimental test results is carried out to investigate the effect of confining pressure, it is found that VM criterion causes unreal impact failure (flexural cracking) of concrete structures.

  9. Mechanics of dual-mode dilative failure in subaqueous sediment deposits

    NASA Astrophysics Data System (ADS)

    You, Yao; Flemings, Peter; Mohrig, David

    2014-07-01

    We introduce dual-mode dilative failure with flume experiments. Dual-mode dilative failure combines slow and steady release of sediments by breaching with periodic sliding, which rapidly releases an internally coherent wedge of sediments. It occurs in dilative sandy deposits. This periodic slope failure results from cyclic evolution of the excess pore pressure in the deposit. Sliding generates large, transient, negative excess pore pressure that strengthens the deposit and allows breaching to occur. During breaching, negative excess pore pressure dissipates, the deposit weakens, and ultimately sliding occurs once again. We show that the sliding frequency is proportional to the coefficient of consolidation. We find that thicker deposits are more susceptible to dual-mode dilative failure. Discovery of dual-mode dilative failure provides a new mechanism to consider when interpreting the sedimentary deposits linked to submarine slope failures.

  10. Evaluation of pressurized water cleaning systems for hardware refurbishment

    NASA Technical Reports Server (NTRS)

    Dillard, Terry W.; Deweese, Charles D.; Hoppe, David T.; Vickers, John H.; Swenson, Gary J.; Hutchens, Dale E.

    1995-01-01

    Historically, refurbishment processes for RSRM motor cases and components have employed environmentally harmful materials. Specifically, vapor degreasing processes consume and emit large amounts of ozone depleting compounds. This program evaluates the use of pressurized water cleaning systems as a replacement for the vapor degreasing process. Tests have been conducted to determine if high pressure water washing, without any form of additive cleaner, is a viable candidate for replacing vapor degreasing processes. This paper discusses the findings thus far of Engineering Test Plan - 1168 (ETP-1168), 'Evaluation of Pressurized Water Cleaning Systems for Hardware Refurbishment.'

  11. Evaluation of Brazed Joints Using Failure Assessment Diagram

    NASA Technical Reports Server (NTRS)

    Flom, Yury

    2012-01-01

    Fitness-for service approach was used to perform structural analysis of the brazed joints consisting of several base metal / filler metal combinations. Failure Assessment Diagrams (FADs) based on tensile and shear stress ratios were constructed and experimentally validated. It was shown that such FADs can provide a conservative estimate of safe combinations of stresses in the brazed joints. Based on this approach, Margins of Safety (MS) of the brazed joints subjected to multi-axial loading conditions can be evaluated..

  12. Elastic geobarometry and the role of brittle failure on pressure release

    NASA Astrophysics Data System (ADS)

    Mazzucchelli, Mattia Luca; Angel, Ross John; Rustioni, Greta; Milani, Sula; Nimis, Paolo; Chiara Domeneghetti, Maria; Marone, Federica; Harris, Jeff W.; Nestola, Fabrizio; Alvaro, Matteo

    2016-04-01

    Mineral inclusions trapped in their hosts can provide fundamental information about geological processes. Recent developments in elastic geobarometry, for example, allow the retrieval of encapsulation pressures for host-inclusion pairs. In principle this method can be applied to any mineral-mineral pair so long as both the residual pressure on an inclusion (Pinc), and the equations of state for both host and inclusion are either known or determined (Angel et al., 2015). However, Angel et al. (2014) outlined some boundary conditions, one of which was that deformation in the host-inclusion pair has to be purely elastic. Thus this caveat would exclude from analysis all the inclusions that are surrounded by cracks, indicative of brittle deformation, which may result in partial or complete release of the Pinc. If however the effects of cracks surrounding trapped mineral inclusions could be quantitatively modelled, then the applicability of "elastic" geobarometry might be extended to a much larger number of inclusion-host pairs. We report the results of a pilot experiment in which the stress states (i.e. the residual pressure) have been determined for 10 olivine inclusions still entrapped in 5 diamonds. Inclusion pressures were determined from the unit-cell volumes of the olivines measured in-situ in the diamonds by X-ray diffraction. The olivine equations of state were determined from the olivine compositions by in-situ X-ray structure refinement. Values of Pinc range from 0.19 to 0.53 GPa. In order to quantify the degree of brittle failure surrounding the inclusions, the same set of samples were also investigated by synchrotron X-ray micro-tomography (SRXTM at TOMCAT, Swiss LightSource). Preliminary results showed that at the spatial resolution of our experiments (pixel size of 0.34μm), 90% of the inclusions trapped in our set of diamonds were surrounded by cracks. The volume of the cracks has been determined from 3D reconstruction with an accuracy of about 4%. Our

  13. Update: Non-Invasive Positive Pressure Ventilation in Chronic Respiratory Failure Due to COPD.

    PubMed

    Altintas, Nejat

    2016-01-01

    Long-term non-invasive positive pressure ventilation (NPPV) has widely been accepted to treat chronic hypercapnic respiratory failure arising from different etiologies. Although the survival benefits provided by long-term NPPV in individuals with restrictive thoracic disorders or stable, slowly-progressing neuromuscular disorders are overwhelming, the benefits provided by long-term NPPV in patients with chronic obstructive pulmonary disease (COPD) remain under question, due to a lack of convincing evidence in the literature. In addition, long-term NPPV reportedly failed in the classic trials to improve important physiological parameters such as arterial blood gases, which might serve as an explanation as to why long-term NPPV has not been shown to substantially impact on survival. However, high intensity NPPV (HI-NPPV) using controlled NPPV with the highest possible inspiratory pressures tolerated by the patient has recently been described as a new and promising approach that is well-tolerated and is also capable of improving important physiological parameters such as arterial blood gases and lung function. This clearly contrasts with the conventional approach of low-intensity NPPV (LI-NPPV) that uses considerably lower inspiratory pressures with assisted forms of NPPV. Importantly, HI-NPPV was very recently shown to be superior to LI-NPPV in terms of improved overnight blood gases, and was also better tolerated than LI-NPPV. Furthermore, HI-NPPV, but not LI-NPPV, improved dyspnea, lung function and disease-specific aspects of health-related quality of life. A recent study showed that long-term treatment with NPPV with increased ventilatory pressures that reduced hypercapnia was associated with significant and sustained improvements in overall mortality. Thus, long-term NPPV seems to offer important benefits in this patient group, but the treatment success might be dependent on effective ventilatory strategies.

  14. Loss of Akap1 Exacerbates Pressure Overload-Induced Cardiac Hypertrophy and Heart Failure.

    PubMed

    Schiattarella, Gabriele G; Boccella, Nicola; Paolillo, Roberta; Cattaneo, Fabio; Trimarco, Valentina; Franzone, Anna; D'Apice, Stefania; Giugliano, Giuseppe; Rinaldi, Laura; Borzacchiello, Domenica; Gentile, Alessandra; Lombardi, Assunta; Feliciello, Antonio; Esposito, Giovanni; Perrino, Cinzia

    2018-01-01

    Left ventricular hypertrophy (LVH) is a major contributor to the development of heart failure (HF). Alterations in cyclic adenosine monophosphate (cAMP)-dependent signaling pathways participate in cardiomyocyte hypertrophy and mitochondrial dysfunction occurring in LVH and HF. cAMP signals are received and integrated by a family of cAMP-dependent protein kinase A (PKA) anchor proteins (AKAPs), tethering PKA to discrete cellular locations. AKAPs encoded by the Akap1 gene (mitoAKAPs) promote PKA mitochondrial targeting, regulating mitochondrial structure and function, reactive oxygen species production, and cell survival. To determine the role of mitoAKAPs in LVH development, in the present investigation, mice with global genetic deletion of Akap1 ( Akap1 -/- ), Akap1 heterozygous ( Akap1 +/- ), and their wild-type ( wt ) littermates underwent transverse aortic constriction (TAC) or SHAM procedure for 1 week. In wt mice, pressure overload induced the downregulation of AKAP121, the major cardiac mitoAKAP. Compared to wt, Akap1 -/- mice did not display basal alterations in cardiac structure or function and cardiomyocyte size or fibrosis. However, loss of Akap1 exacerbated LVH and cardiomyocyte hypertrophy induced by pressure overload and accelerated the progression toward HF in TAC mice, and these changes were not observed upon prevention of AKAP121 degradation in seven in absentia homolog 2 ( Siah2 ) knockout mice ( Siah2 -/- ). Loss of Akap1 was also associated to a significant increase in cardiac apoptosis as well as lack of activation of Akt signaling after pressure overload. Taken together, these results demonstrate that in vivo genetic deletion of Akap1 enhances LVH development and accelerates pressure overload-induced cardiac dysfunction, pointing at Akap1 as a novel repressor of pathological LVH. These results confirm and extend the important role of mitoAKAPs in cardiac response to stress.

  15. Acute Respiratory Failure in Cardiac Transplant Recipients.

    PubMed

    Komurcu, Ozgur; Ozdemirkan, Aycan; Camkiran Firat, Aynur; Zeyneloglu, Pinar; Sezgin, Atilla; Pirat, Arash

    2015-11-01

    This study sought to evaluate the incidence, risk factors, and outcomes of acute respiratory failure in cardiac transplant recipients. Cardiac transplant recipients >15 years of age and readmitted to the intensive care unit after cardiac transplant between 2005 and 2015 were included. Thirty-nine patients were included in the final analyses. Patients with acute respiratory failure and without acute respiratory failure were compared. The most frequent causes of readmission were routine intensive care unit follow-up after endomyocardial biopsy, heart failure, sepsis, and pneumonia. Patients who were readmitted to the intensive care unit were further divided into 2 groups based on presence of acute respiratory failure. Patients' ages and body weights did not differ between groups. The groups were not different in terms of comorbidities. The admission sequential organ failure assessment scores were higher in patients with acute respiratory failure. Patients with acute respiratory failure were more likely to use bronchodilators and n-acetylcysteine before readmission. Mean peak inspiratory pressures were higher in patients in acute respiratory failure. Patients with acute respiratory failure developed sepsis more frequently and they were more likely to have hypotension. Patients with acute respiratory failure had higher values of serum creatinine before admission to intensive care unit and in the first day of intensive care unit. Patients with acute respiratory failure had more frequent bilateral opacities on chest radiographs and positive blood and urine cultures. Duration of intensive care unit and hospital stays were not statistically different between groups. Mortality in patients with acute respiratory failure was 76.5% compared with 0% in patients without acute respiratory failure. A significant number of cardiac transplant recipients were readmitted to the intensive care unit. Patients presenting with acute respiratory failure on readmission more frequently

  16. The failure of earthquake failure models

    USGS Publications Warehouse

    Gomberg, J.

    2001-01-01

    In this study I show that simple heuristic models and numerical calculations suggest that an entire class of commonly invoked models of earthquake failure processes cannot explain triggering of seismicity by transient or "dynamic" stress changes, such as stress changes associated with passing seismic waves. The models of this class have the common feature that the physical property characterizing failure increases at an accelerating rate when a fault is loaded (stressed) at a constant rate. Examples include models that invoke rate state friction or subcritical crack growth, in which the properties characterizing failure are slip or crack length, respectively. Failure occurs when the rate at which these grow accelerates to values exceeding some critical threshold. These accelerating failure models do not predict the finite durations of dynamically triggered earthquake sequences (e.g., at aftershock or remote distances). Some of the failure models belonging to this class have been used to explain static stress triggering of aftershocks. This may imply that the physical processes underlying dynamic triggering differs or that currently applied models of static triggering require modification. If the former is the case, we might appeal to physical mechanisms relying on oscillatory deformations such as compaction of saturated fault gouge leading to pore pressure increase, or cyclic fatigue. However, if dynamic and static triggering mechanisms differ, one still needs to ask why static triggering models that neglect these dynamic mechanisms appear to explain many observations. If the static and dynamic triggering mechanisms are the same, perhaps assumptions about accelerating failure and/or that triggering advances the failure times of a population of inevitable earthquakes are incorrect.

  17. Ceramic pressure housing with metal endcaps

    DOEpatents

    Downing, Jr., John P.; DeRoos, Bradley G.; Hackman, Donald J.

    1995-01-01

    A housing for the containment of instrumentation in a high pressure fluid environment that consists of a metallic endcap and ceramic cylinder bonded together. The improvement comprises a structure which results in the improved sealing of said housing as the fluid pressure increases. The cylindrical ceramic tube and endcap are dimensioned such that mechanical failure does not occur when exposed to the desired external operating pressures which includes up to 36,000 feet of water. The housing is designed to withstand the external operating pressures without being subject to mechanical failure or excessive deformation which results in the loss of pressure housing integrity via cracking or deformation of the ceramic tube, deformation of the endcap, or from failure of the bonding agent.

  18. Ceramic pressure housing with metal endcaps

    DOEpatents

    Downing, J.P. Jr.; DeRoos, B.G.; Hackman, D.J.

    1995-06-27

    A housing is disclosed for the containment of instrumentation in a high pressure fluid environment that consists of a metallic endcap and ceramic cylinder bonded together. The improvement comprises a structure which results in the improved sealing of said housing as the fluid pressure increases. The cylindrical ceramic tube and endcap are dimensioned such that mechanical failure does not occur when exposed to the desired external operating pressures which includes up to 36,000 feet of water. The housing is designed to withstand the external operating pressures without being subject to mechanical failure or excessive deformation which results in the loss of pressure housing integrity via cracking or deformation of the ceramic tube, deformation of the endcap, or from failure of the bonding agent. 9 figs.

  19. Transient radon signals driven by fluid pressure pulse, micro-crack closure, and failure during granite deformation experiments

    NASA Astrophysics Data System (ADS)

    Girault, Frédéric; Schubnel, Alexandre; Pili, Éric

    2017-09-01

    In seismically active fault zones, various crustal fluids including gases are released at the surface. Radon-222, a radioactive gas naturally produced in rocks, is used in volcanic and tectonic contexts to illuminate crustal deformation or earthquake mechanisms. At some locations, intriguing radon signals have been recorded before, during, or after tectonic events, but such observations remain controversial, mainly because physical characterization of potential radon anomalies from the upper crust is lacking. Here we conducted several month-long deformation experiments under controlled dry upper crustal conditions with a triaxial cell to continuously monitor radon emission from crustal rocks affected by three main effects: a fluid pressure pulse, micro-crack closure, and differential stress increase to macroscopic failure. We found that these effects are systematically associated with a variety of radon signals that can be explained using a first-order advective model of radon transport. First, connection to a source of deep fluid pressure (a fluid pressure pulse) is associated with a large transient radon emission increase (factor of 3-7) compared with the background level. We reason that peak amplitude is governed by the accumulation time and the radon source term, and that peak duration is controlled by radioactive decay, permeability, and advective losses of radon. Second, increasing isostatic compression is first accompanied by an increase in radon emission followed by a decrease beyond a critical pressure representing the depth below which crack closure hampers radon emission (150-250 MPa, ca. 5.5-9.5 km depth in our experiments). Third, the increase of differential stress, and associated shear and volumetric deformation, systematically triggers significant radon peaks (ca. 25-350% above background level) before macroscopic failure, by connecting isolated cracks, which dramatically enhances permeability. The detection of transient radon signals before rupture

  20. Transient radon signals driven by fluid pressure pulse, micro-crack closure, and failure during granite deformation experiments

    NASA Astrophysics Data System (ADS)

    Schubnel, A.; Girault, F.; Pili, E.

    2017-12-01

    In seismically active fault zones, various crustal fluids including gases are released at the surface. Radon-222, a radioactive gas naturally produced in rocks, is used in volcanic and tectonic contexts to illuminate crustal deformation or earthquake mechanisms. At some locations, intriguing radon signals have been recorded before, during, or after tectonic events, but such observations remain controversial, mainly because physical characterization of potential radon anomalies from the upper crust is lacking. Here we conducted several month-long deformation experiments under controlled dry upper crustal conditions with a triaxial cell to continuously monitor radon emission from crustal rocks affected by three main effects: a fluid pressure pulse, micro-crack closure, and differential stress increase to macroscopic failure. We found that these effects are systematically associated with a variety of radon signals that can be explained using a first-order advective model of radon transport. First, connection to a source of deep fluid pressure (a fluid pressure pulse) is associated with a large transient radon emission increase (factor of 3-7) compared with the background level. We reason that peak amplitude is governed by the accumulation time and the radon source term, and that peak duration is controlled by radioactive decay, permeability, and advective losses of radon. Second, increasing isostatic compression is first accompanied by an increase in radon emission followed by a decrease beyond a critical pressure representing the depth below which crack closure hampers radon emission (150-250 MPa, ca. 5.5-9.5 km depth in our experiments). Third, the increase of differential stress, and associated shear and volumetric deformation, systematically triggers significant radon peaks (ca. 25-350% above background level) before macroscopic failure, by connecting isolated cracks, which dramatically enhances permeability. The detection of transient radon signals before rupture

  1. Electrical Pressurization Concept for the Orion MPCV European Service Module Propulsion System

    NASA Technical Reports Server (NTRS)

    Meiss, Jan-Hendrik; Weber, Jorg; Ierardo, Nicola; Quinn, Frank D.; Paisley, Jonathan

    2015-01-01

    The paper presents the design of the pressurization system of the European Service Module (ESM) of the Orion Multi-Purpose Crew Vehicle (MPCV). Being part of the propulsion subsystem, an electrical pressurization concept is implemented to condition propellants according to the engine needs via a bang-bang regulation system. Separate pressurization for the oxidizer and the fuel tank permits mixture ratio adjustments and prevents vapor mixing of the two hypergolic propellants during nominal operation. In case of loss of pressurization capability of a single side, the system can be converted into a common pressurization system. The regulation concept is based on evaluation of a set of tank pressure sensors and according activation of regulation valves, based on a single-failure tolerant weighting of three pressure signals. While regulation is performed on ESM level, commanding of regulation parameters as well as failure detection, isolation and recovery is performed from within the Crew Module, developed by Lockheed Martin Space System Company. The overall design and development maturity presented is post Preliminary Design Review (PDR) and reflects the current status of the MPCV ESM pressurization system.

  2. Failure Mechanisms of Hollow Fiber Supported Ionic Liquid Membranes

    PubMed Central

    Zeh, Matthew; Wickramanayake, Shan; Hopkinson, David

    2016-01-01

    Hollow fiber supported ionic liquid membranes (SILMs) were tested using the bubble point method to investigate potential failure modes, including the maximum transmembrane pressure before loss of the ionic liquid from the support. Porous hollow fiber supports were fabricated with different pore morphologies using Matrimid® and Torlon® as the polymeric material and 1-hexyl-3-methylimidalzolium bis(trifluoromethylsulfonyl)imide ([C6mim][Tf2N]) as the ionic liquid (IL) component. Hollow fiber SILMs were tested for their maximum pressure before failure, with pressure applied either from the bore side or shell side. It was found that the membranes exhibited one or more of three different modes of failure when pressurized: liquid loss (occurring at the bubble point), rupture, and collapse. PMID:27023620

  3. Terahertz NDE of Stressed Composite Overwrapped Pressure Vessels - Initial Testing

    NASA Technical Reports Server (NTRS)

    Madaras, Eric I.; Seebo, Jeffrey P.; Anatasi, Robert F.

    2009-01-01

    Terahertz radiation nondestructive evaluation was applied to a set of Kevlar composite overwrapped pressure vessel bottles that had undergone a series of thermal and pressure tests to simulate stress rupture effects. The bottles in these nondestructive evaluation tests were bottles that had not ruptured but had survived various times at the elevated load and temperature levels. Some of the bottles showed evidence of minor composite failures. The terahertz radiation did detect visible surface flaws, but did not detect any internal chemical or material degradation of the thin overwraps.

  4. Natriuretic Peptide and Clinical Evaluation in the Diagnosis of Heart Failure Hemodynamic Profile: Comparison with Tissue Doppler Echocardiography.

    PubMed

    Almeida Junior, Gustavo Luiz Gouvêa de; Clausell, Nadine; Garcia, Marcelo Iorio; Esporcatte, Roberto; Rangel, Fernando Oswaldo Dias; Rocha, Ricardo Mourilhe; Beck-da-Silva, Luis; Silva, Fabricio Braga da; Gorgulho, Paula de Castro Carvalho; Xavier, Sergio Salles

    2018-03-01

    Physical examination and B-type natriuretic peptide (BNP) have been used to estimate hemodynamics and tailor therapy of acute decompensated heart failure (ADHF) patients. However, correlation between these parameters and left ventricular filling pressures is controversial. This study was designed to evaluate the diagnostic accuracy of physical examination, chest radiography (CR) and BNP in estimating left atrial pressure (LAP) as assessed by tissue Doppler echocardiogram. Patients admitted with ADHF were prospectively assessed. Diagnostic characteristics of physical signs of heart failure, CR and BNP in predicting elevation (> 15 mm Hg) of LAP, alone or combined, were calculated. Spearman test was used to analyze the correlation between non-normal distribution variables. The level of significance was 5%. Forty-three patients were included, with mean age of 69.9 ± 11.1years, left ventricular ejection fraction of 25 ± 8.0%, and BNP of 1057 ± 1024.21 pg/mL. Individually, all clinical, CR or BNP parameters had a poor performance in predicting LAP ≥ 15 mm Hg. A clinical score of congestion had the poorest performance [area under the receiver operating characteristic curve (AUC) 0.53], followed by clinical score + CR (AUC 0.60), clinical score + CR + BNP > 400 pg/mL (AUC 0.62), and clinical score + CR + BNP > 1000 pg/mL (AUC 0.66). Physical examination, CR and BNP had a poor performance in predicting a LAP ≥ 15 mm Hg. Using these parameters alone or in combination may lead to inaccurate estimation of hemodynamics.

  5. Blood pressure reactivity to psychological stress is associated with clinical outcomes in patients with heart failure.

    PubMed

    Sherwood, Andrew; Hill, LaBarron K; Blumenthal, James A; Adams, Kirkwood F; Paine, Nicola J; Koch, Gary G; O'Connor, Christopher M; Johnson, Kristy S; Hinderliter, Alan L

    2017-09-01

    Cardiovascular (CV) reactivity to psychological stress has been implicated in the development and exacerbation of cardiovascular disease (CVD). Although high CV reactivity traditionally is thought to convey greater risk of CVD, the relationship between reactivity and clinical outcomes is inconsistent and may depend on the patient population under investigation. The present study examined CV reactivity in patients with heart failure (HF) and its potential association with long-term clinical outcomes. One hundred ninety-nine outpatients diagnosed with HF, with ejection fraction ≤40%, underwent an evaluation of blood pressure (BP) and heart rate reactivity to a laboratory-based simulated public-speaking stressor. Cox proportional hazards regression models were used to examine the prospective association between BP and heart rate reactivity on a combined end point of death or CV hospitalization over a 5-year median follow-up period. Both systolic blood pressure (SBP) and diastolic blood pressure (DBP) reactivity, quantified as continuous variables, were inversely related to risk of death or CV hospitalization (Ps < .01) after controlling for established risk factors, including HF disease severity and etiology. In similar models, heart rate reactivity was unrelated to outcome (P = .12). In models with tertiles of reactivity, high SBP reactivity, compared with intermediate SBP reactivity, was associated with lower risk (hazard ratio [HR] = .498, 95% CI .335-.742, P =.001), whereas low SBP reactivity did not differ from intermediate reactivity. For DBP, high reactivity was marginally associated with lower risk compared with intermediate DBP reactivity (HR = .767, 95% CI .515-1.14, P =.193), whereas low DBP reactivity was associated with greater risk (HR = 1.49, 95% CI 1.027-2.155, P =.0359). No relationship of heart rate reactivity to outcome was identified. For HF patients with reduced ejection fraction, a robust increase in BP evoked by a laboratory

  6. Pressure ulcers: development and psychometric evaluation of the attitude towards pressure ulcer prevention instrument (APuP).

    PubMed

    Beeckman, D; Defloor, T; Demarré, L; Van Hecke, A; Vanderwee, K

    2010-11-01

    Pressure ulcers continue to be a significant problem in hospitals, nursing homes and community care settings. Pressure ulcer incidence is widely accepted as an indicator for the quality of care. Negative attitudes towards pressure ulcer prevention may result in suboptimal preventive care. A reliable and valid instrument to assess attitudes towards pressure ulcer prevention is lacking. Development and psychometric evaluation of the Attitude towards Pressure ulcer Prevention instrument (APuP). Prospective psychometric instrument validation study. A literature review was performed to design the instrument. Content validity was evaluated by nine European pressure ulcer experts and five experts in psychometric instrument validation in a double Delphi procedure. A convenience sample of 258 nurses and 291 nursing students from Belgium and The Netherlands participated in order to evaluate construct validity and stability reliability of the instrument. The data were collected between February and May 2008. A factor analysis indicated the construct of a 13 item instrument in a five factor solution: (1) attitude towards personal competency to prevent pressure ulcers (three items); (2) attitude towards the priority of pressure ulcer prevention (three items); (3) attitude towards the impact of pressure ulcers (three items); (4) attitude towards personal responsibility in pressure ulcer prevention (two items); and (5) attitude towards confidence in the effectiveness of prevention (two items). This five factor solution accounted for 61.4% of the variance in responses related to attitudes towards pressure ulcer prevention. All items demonstrated factor loadings over 0.60. The instrument produced similar results during stability testing [ICC=0.88 (95% CI=0.84-0.91, P<0.001)]. For the total instrument, the internal consistency (Cronbachs alpha) was 0.79. The APuP is a psychometrically sound instrument that can be used to effectively assess attitudes towards pressure ulcer prevention

  7. ELABELA-APJ axis protects from pressure overload heart failure and angiotensin II-induced cardiac damage.

    PubMed

    Sato, Teruki; Sato, Chitose; Kadowaki, Ayumi; Watanabe, Hiroyuki; Ho, Lena; Ishida, Junji; Yamaguchi, Tomokazu; Kimura, Akinori; Fukamizu, Akiyoshi; Penninger, Josef M; Reversade, Bruno; Ito, Hiroshi; Imai, Yumiko; Kuba, Keiji

    2017-06-01

    Elabela/Toddler/Apela (ELA) has been identified as a novel endogenous peptide ligand for APJ/Apelin receptor/Aplnr. ELA plays a crucial role in early cardiac development of zebrafish as well as in maintenance of self-renewal of human embryonic stem cells. Apelin was the first identified APJ ligand, and exerts positive inotropic heart effects and regulates the renin-angiotensin system. The aim of this study was to investigate the biological effects of ELA in the cardiovascular system. Continuous infusion of ELA peptide significantly suppressed pressure overload-induced cardiac hypertrophy, fibrosis and impaired contractility in mice. ELA treatment reduced mRNA expression levels of genes associated with heart failure and fibrosis. The cardioprotective effects of ELA were diminished in APJ knockout mice, indicating that APJ is the key receptor for ELA in the adult heart. Mechanistically, ELA downregulated angiotensin-converting enzyme (ACE) expression in the stressed hearts, whereas it showed little effects on angiotensin-converting enzyme 2 (ACE2) expression, which are distinct from the effects of Apelin. FoxM1 transcription factor, which induces ACE expression in the stressed hearts, was downregulated by ELA but not by Apelin. ELA antagonized angiotensin II-induced hypertension, cardiac hypertrophy, and fibrosis in mice. The ELA-APJ axis protects from pressure overload-induced heart failure possibly via suppression of ACE expression and pathogenic angiotensin II signalling. The different effects of ELA and Apelin on the expression of ACE and ACE2 implicate fine-tuned mechanisms for a ligand-induced APJ activation and downstream signalling. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions please email: journals.permissions@oup.com.

  8. Voluntary Consensus Organization Standards for Nondestructive Evaluation of Thin-Walled Metallic Liners and Composite Overwraps in Composite Overwrapped Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Waller, Jess; Saulsberry, Regor

    2012-01-01

    NASA fracture control requirements outlined in NASA-STD-5009 and NASA-STD-5014 are predicated on the availability and use of sensitive nondestructive evaluation (NDE) methods that can detect and monitor defects, thereby providing data that can be used to predict failure or reduce the risk of failure in fracture critical components. However, in the case of composite materials and components, including composite overwrapped pressure vessels (COPVs), the effect of defects is poorly understood, the NDE methods used to evaluate locate and size defects are typically at lower technical readiness level than analogous NDE methods used for metals, and demonstration studies to verify the probability of detection (POD) are generally lacking or unavailable. These factors together make failure prediction of fracture critical composite materials and components based on size, quantity, or orientation of defects nearly impossible. Also, when inspecting metal liners in as-manufactured COPVs, sensitivity is lost and only the inner surface of the liner is accessible. Also, NDE of COPVs as applied during manufacturing varies significantly from manufacturer to manufacturer and has not yet been standardized. Although requirements exist to perform NDE immediately after manufacturing to establish initial integrity of the parts, procedural detail for NDE of composites is still nonexistent or under development. For example, in practice, only a visual inspection of COPVs is performed during manufacturing and service, leaving in question whether defects of concern, for example, bridging, overwrap winding anomalies, impact damage below visible threshold, out-of-family strain growth, and liner buckling have been adequately detected and monitored. To address these shortcomings, in 2005 the NASA Nondestructive Evaluation Working Group (NNWG) began funding work to develop and adopt standards for nondestructive evaluation of aerospace composites in collaboration with the American Society for Testing

  9. Clinical evaluation of a new pressure ulcer risk assessment instrument, the Pressure Ulcer Risk Primary or Secondary Evaluation Tool (PURPOSE T).

    PubMed

    Coleman, Susanne; Smith, Isabelle L; McGinnis, Elizabeth; Keen, Justin; Muir, Delia; Wilson, Lyn; Stubbs, Nikki; Dealey, Carol; Brown, Sarah; Nelson, E Andrea; Nixon, Jane

    2018-02-01

    To test the psychometric properties and clinical usability of a new Pressure Ulcer Risk Assessment Instrument including inter-rater and test-retest reliability, convergent validity and data completeness. Methodological and practical limitations associated with traditional Pressure Ulcer Risk Assessment Instruments, prompted a programme to work to develop a new instrument, as part of the National Institute for Health Research funded, Pressure UlceR Programme Of reSEarch (RP-PG-0407-10056). Observational field test. For this clinical evaluation 230 patients were purposefully sampled across four broad levels of pressure ulcer risk with representation from four secondary care and four community NHS Trusts in England. Blinded and simultaneous paired (ward/community nurse and expert nurse) PURPOSE-T assessments were undertaken. Follow-up retest was undertaken by the expert nurse. Field notes of PURPOSE-T use were collected. Data were collected October 2012-January 2013. The clinical evaluation demonstrated "very good" (kappa) inter-rater and test-retest agreement for PURPOSE-T assessment decision overall. The percentage agreement for "problem/no problem" was over 75% for the main risk factors. Convergent validity demonstrated moderate to high associations with other measures of similar constructs. The PURPOSE-T evaluation facilitated the initial validation and clinical usability of the instrument and demonstrated that PURPOSE-T is suitable of use in clinical practice. Further study is needed to evaluate the impact of using the instrument on care processes and outcomes. © 2017 The Authors. Journal of Advanced Nursing Published by John Wiley & Sons Ltd.

  10. Prognostic Factors in Severe Chagasic Heart Failure

    PubMed Central

    Costa, Sandra de Araújo; Rassi, Salvador; Freitas, Elis Marra da Madeira; Gutierrez, Natália da Silva; Boaventura, Fabiana Miranda; Sampaio, Larissa Pereira da Costa; Silva, João Bastista Masson

    2017-01-01

    Background Prognostic factors are extensively studied in heart failure; however, their role in severe Chagasic heart failure have not been established. Objectives To identify the association of clinical and laboratory factors with the prognosis of severe Chagasic heart failure, as well as the association of these factors with mortality and survival in a 7.5-year follow-up. Methods 60 patients with severe Chagasic heart failure were evaluated regarding the following variables: age, blood pressure, ejection fraction, serum sodium, creatinine, 6-minute walk test, non-sustained ventricular tachycardia, QRS width, indexed left atrial volume, and functional class. Results 53 (88.3%) patients died during follow-up, and 7 (11.7%) remained alive. Cumulative overall survival probability was approximately 11%. Non-sustained ventricular tachycardia (HR = 2.11; 95% CI: 1.04 - 4.31; p<0.05) and indexed left atrial volume ≥ 72 mL/m2 (HR = 3.51; 95% CI: 1.63 - 7.52; p<0.05) were the only variables that remained as independent predictors of mortality. Conclusions The presence of non-sustained ventricular tachycardia on Holter and indexed left atrial volume > 72 mL/m2 are independent predictors of mortality in severe Chagasic heart failure, with cumulative survival probability of only 11% in 7.5 years. PMID:28443956

  11. International Space Station (ISS) Low Pressure Intramodule Quick Disconnect Failures

    NASA Technical Reports Server (NTRS)

    Lewis, John F.; Harris, Danny; Link, Dwight; Morrison, Russel

    2004-01-01

    A failure of an ISS intermodule Quick Disconnect (QD) during protoflight vibration testing of ISS regenerative Environmental Control and Life Support (ECLS) hardware led to the discovery of QD design, manufacturing, and test flaws which can yield the male QD susceptible to failure of the secondary housing seal and inadequate housing assembly locking mechanisms. Discovery of this failure had large implications when considering that currently there are 399 similar units on orbit and approximately 1100 units on the ground integrated into flight hardware. Discovery of the nature of the failure required testing and analysis and implementation of a recovery plan requiring part screening and review of element level and project hazard analysis to determine if secondary seals are required. Implementation also involves coordination with the Nodes and MPLM project offices, Regenerative ECLS Project, ISS Payloads, JAXA, ESA, and ISS Logistics and Maintenance.

  12. RBFox1-mediated RNA splicing regulates cardiac hypertrophy and heart failure.

    PubMed

    Gao, Chen; Ren, Shuxun; Lee, Jae-Hyung; Qiu, Jinsong; Chapski, Douglas J; Rau, Christoph D; Zhou, Yu; Abdellatif, Maha; Nakano, Astushi; Vondriska, Thomas M; Xiao, Xinshu; Fu, Xiang-Dong; Chen, Jau-Nian; Wang, Yibin

    2016-01-01

    RNA splicing is a major contributor to total transcriptome complexity; however, the functional role and regulation of splicing in heart failure remain poorly understood. Here, we used a total transcriptome profiling and bioinformatic analysis approach and identified a muscle-specific isoform of an RNA splicing regulator, RBFox1 (also known as A2BP1), as a prominent regulator of alternative RNA splicing during heart failure. Evaluation of developing murine and zebrafish hearts revealed that RBFox1 is induced during postnatal cardiac maturation. However, we found that RBFox1 is markedly diminished in failing human and mouse hearts. In a mouse model, RBFox1 deficiency in the heart promoted pressure overload-induced heart failure. We determined that RBFox1 is a potent regulator of RNA splicing and is required for a conserved splicing process of transcription factor MEF2 family members that yields different MEF2 isoforms with differential effects on cardiac hypertrophic gene expression. Finally, induction of RBFox1 expression in murine pressure overload models substantially attenuated cardiac hypertrophy and pathological manifestations. Together, this study identifies regulation of RNA splicing by RBFox1 as an important player in transcriptome reprogramming during heart failure that influence pathogenesis of the disease.

  13. RBFox1-mediated RNA splicing regulates cardiac hypertrophy and heart failure

    PubMed Central

    Gao, Chen; Ren, Shuxun; Lee, Jae-Hyung; Qiu, Jinsong; Chapski, Douglas J.; Rau, Christoph D.; Zhou, Yu; Abdellatif, Maha; Nakano, Astushi; Vondriska, Thomas M.; Xiao, Xinshu; Fu, Xiang-Dong; Chen, Jau-Nian; Wang, Yibin

    2015-01-01

    RNA splicing is a major contributor to total transcriptome complexity; however, the functional role and regulation of splicing in heart failure remain poorly understood. Here, we used a total transcriptome profiling and bioinformatic analysis approach and identified a muscle-specific isoform of an RNA splicing regulator, RBFox1 (also known as A2BP1), as a prominent regulator of alternative RNA splicing during heart failure. Evaluation of developing murine and zebrafish hearts revealed that RBFox1 is induced during postnatal cardiac maturation. However, we found that RBFox1 is markedly diminished in failing human and mouse hearts. In a mouse model, RBFox1 deficiency in the heart promoted pressure overload–induced heart failure. We determined that RBFox1 is a potent regulator of RNA splicing and is required for a conserved splicing process of transcription factor MEF2 family members that yields different MEF2 isoforms with differential effects on cardiac hypertrophic gene expression. Finally, induction of RBFox1 expression in murine pressure overload models substantially attenuated cardiac hypertrophy and pathological manifestations. Together, this study identifies regulation of RNA splicing by RBFox1 as an important player in transcriptome reprogramming during heart failure that influence pathogenesis of the disease. PMID:26619120

  14. Physiological Effects of Positive Pressure Ventilation.

    DTIC Science & Technology

    1992-05-01

    function in the patient with respiratory failure . In R. R. Kirby, M. J. Banner, & J. B. Downs (Eds.), Clinical Applications of Ventilatory Su2Rort (pp. 301...G., Blehschmidt, N. G., & Linder, W. J. (1990). Positive-pressure ventilation with positive end-expiratory pressure and atrial natriuretic peptide ...Acute Resniratorv Failure . New York: Churchill Livingstone. Ventilation 1 Physiological Effects of Positive Pressure Ventilation Dennis L. Oakes, RN, BSN

  15. Noninvasive Positive Pressure Ventilation for Chronic Respiratory Failure Patients With Stable Chronic Obstructive Pulmonary Disease (COPD)

    PubMed Central

    2012-01-01

    Executive Summary In July 2010, the Medical Advisory Secretariat (MAS) began work on a Chronic Obstructive Pulmonary Disease (COPD) evidentiary framework, an evidence-based review of the literature surrounding treatment strategies for patients with COPD. This project emerged from a request by the Health System Strategy Division of the Ministry of Health and Long-Term Care that MAS provide them with an evidentiary platform on the effectiveness and cost-effectiveness of COPD interventions. After an initial review of health technology assessments and systematic reviews of COPD literature, and consultation with experts, MAS identified the following topics for analysis: vaccinations (influenza and pneumococcal), smoking cessation, multidisciplinary care, pulmonary rehabilitation, long-term oxygen therapy, noninvasive positive pressure ventilation for acute and chronic respiratory failure, hospital-at-home for acute exacerbations of COPD, and telehealth (including telemonitoring and telephone support). Evidence-based analyses were prepared for each of these topics. For each technology, an economic analysis was also completed where appropriate. In addition, a review of the qualitative literature on patient, caregiver, and provider perspectives on living and dying with COPD was conducted, as were reviews of the qualitative literature on each of the technologies included in these analyses. The Chronic Obstructive Pulmonary Disease Mega-Analysis series is made up of the following reports, which can be publicly accessed at the MAS website at: http://www.hqontario.ca/en/mas/mas_ohtas_mn.html. Chronic Obstructive Pulmonary Disease (COPD) Evidentiary Framework Influenza and Pneumococcal Vaccinations for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Smoking Cessation for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Community-Based Multidisciplinary Care for Patients With Stable Chronic Obstructive

  16. Noninvasive Positive Pressure Ventilation for Acute Respiratory Failure Patients With Chronic Obstructive Pulmonary Disease (COPD)

    PubMed Central

    McCurdy, BR

    2012-01-01

    Executive Summary In July 2010, the Medical Advisory Secretariat (MAS) began work on a Chronic Obstructive Pulmonary Disease (COPD) evidentiary framework, an evidence-based review of the literature surrounding treatment strategies for patients with COPD. This project emerged from a request by the Health System Strategy Division of the Ministry of Health and Long-Term Care that MAS provide them with an evidentiary platform on the effectiveness and cost-effectiveness of COPD interventions. After an initial review of health technology assessments and systematic reviews of COPD literature, and consultation with experts, MAS identified the following topics for analysis: vaccinations (influenza and pneumococcal), smoking cessation, multidisciplinary care, pulmonary rehabilitation, long-term oxygen therapy, noninvasive positive pressure ventilation for acute and chronic respiratory failure, hospital-at-home for acute exacerbations of COPD, and telehealth (including telemonitoring and telephone support). Evidence-based analyses were prepared for each of these topics. For each technology, an economic analysis was also completed where appropriate. In addition, a review of the qualitative literature on patient, caregiver, and provider perspectives on living and dying with COPD was conducted, as were reviews of the qualitative literature on each of the technologies included in these analyses. The Chronic Obstructive Pulmonary Disease Mega-Analysis series is made up of the following reports, which can be publicly accessed at the MAS website at: http://www.hqontario.ca/en/mas/mas_ohtas_mn.html. Chronic Obstructive Pulmonary Disease (COPD) Evidentiary Framework Influenza and Pneumococcal Vaccinations for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Smoking Cessation for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Community-Based Multidisciplinary Care for Patients With Stable Chronic Obstructive

  17. Design and evaluation of a failure detection and isolation algorithm for restructurable control systems

    NASA Technical Reports Server (NTRS)

    Weiss, Jerold L.; Hsu, John Y.

    1986-01-01

    The use of a decentralized approach to failure detection and isolation for use in restructurable control systems is examined. This work has produced: (1) A method for evaluating fundamental limits to FDI performance; (2) Application using flight recorded data; (3) A working control element FDI system with maximal sensitivity to critical control element failures; (4) Extensive testing on realistic simulations; and (5) A detailed design methodology involving parameter optimization (with respect to model uncertainties) and sensitivity analyses. This project has concentrated on detection and isolation of generic control element failures since these failures frequently lead to emergency conditions and since knowledge of remaining control authority is essential for control system redesign. The failures are generic in the sense that no temporal failure signature information was assumed. Thus, various forms of functional failures are treated in a unified fashion. Such a treatment results in a robust FDI system (i.e., one that covers all failure modes) but sacrifices some performance when detailed failure signature information is known, useful, and employed properly. It was assumed throughout that all sensors are validated (i.e., contain only in-spec errors) and that only the first failure of a single control element needs to be detected and isolated. The FDI system which has been developed will handle a class of multiple failures.

  18. Vascular Physiology according to Clinical Scenario in Patients with Acute Heart Failure: Evaluation using the Cardio-Ankle Vascular Index.

    PubMed

    Goto, Toshihiko; Wakami, Kazuaki; Mori, Kento; Kikuchi, Shohei; Fukuta, Hidekatsu; Ohte, Nobuyuki

    2016-09-01

    Increased aortic stiffness may be an important cause of acute heart failure (AHF). Clinical scenario (CS), which classifies the pathophysiology of AHF based on the initial systolic blood pressure (sBP), was proposed to provide the most appropriate therapy for AHF patients. In CS, elevated aortic stiffness, vascular failure, has been considered as a feature of patients categorized as CS1 (sBP > 140 mmHg at initial presentation). However, whether elevated aortic stiffness, vascular failure, is present in such patients has not been fully elucidated. Therefore, we assessed aortic stiffness in AHF patients using the cardio-ankle vascular index (CAVI), which is considered to be independent of instantaneous blood pressure. Sixty-four consecutive AHF patients (mean age, 70.6 ± 12.8 years; 39 men) were classified with CS, based on their initial sBP: CS1: sBP > 140 mmHg (n = 29); CS2: sBP 100-140 mmHg (n = 22); and CS3: sBP < 100 mmHg (n = 13). There were significant group differences in CAVI (CS1 vs. CS2 vs. CS3: 9.7 ± 1.4 vs. 8.4 ± 1.7 vs. 8.3 ± 1.7, p = 0.006, analysis of variance). CAVI was significantly higher in CS1 than in CS2 (p = 0.02) and CS3 (p = 0.04). CAVI did not significantly correlate with sBP at the time of measurement of CAVI (r = 0.24 and p = 0.06). Aortic stiffness assessed using blood pressure-independent methodology apparently increased in CS1 AHF patients. We conclude that vascular failure is a feature of CS1 AHF initiation.

  19. In-Flight Validation of a Pilot Rating Scale for Evaluating Failure Transients in Electronic Flight Control Systems

    NASA Technical Reports Server (NTRS)

    Kalinowski, Kevin F.; Tucker, George E.; Moralez, Ernesto, III

    2006-01-01

    Engineering development and qualification of a Research Flight Control System (RFCS) for the Rotorcraft Aircrew Systems Concepts Airborne Laboratory (RASCAL) JUH-60A has motivated the development of a pilot rating scale for evaluating failure transients in fly-by-wire flight control systems. The RASCAL RFCS includes a highly-reliable, dual-channel Servo Control Unit (SCU) to command and monitor the performance of the fly-by-wire actuators and protect against the effects of erroneous commands from the flexible, but single-thread Flight Control Computer. During the design phase of the RFCS, two piloted simulations were conducted on the Ames Research Center Vertical Motion Simulator (VMS) to help define the required performance characteristics of the safety monitoring algorithms in the SCU. Simulated failures, including hard-over and slow-over commands, were injected into the command path, and the aircraft response and safety monitor performance were evaluated. A subjective Failure/Recovery Rating (F/RR) scale was developed as a means of quantifying the effects of the injected failures on the aircraft state and the degree of pilot effort required to safely recover the aircraft. A brief evaluation of the rating scale was also conducted on the Army/NASA CH-47B variable stability helicopter to confirm that the rating scale was likely to be equally applicable to in-flight evaluations. Following the initial research flight qualification of the RFCS in 2002, a flight test effort was begun to validate the performance of the safety monitors and to validate their design for the safe conduct of research flight testing. Simulated failures were injected into the SCU, and the F/RR scale was applied to assess the results. The results validate the performance of the monitors, and indicate that the Failure/Recovery Rating scale is a very useful tool for evaluating failure transients in fly-by-wire flight control systems.

  20. Episodic Sediment Failure in Northern Flemish Pass, Eastern Canadian Margin: Interplay of Seismicity, Contour Current Winnowing, and Excess Pore Pressures

    NASA Astrophysics Data System (ADS)

    Piper, D.

    2015-12-01

    Episodic sediment failures are recognised on continental slopes around Flemish Pass and Orphan Basin from multibeam bathymetry, seismic reflection profiles and piston cores. Seismic stratigraphy is tied to published long cores with O-isotope data back to before MIS 6 and carbonate rich Heinrich layers in places produce marker reflections in high-resolution sparker profiles. Heinrich layers, radiocarbon dates and peaks in diatom abundance provide core chronology. Slope sedimentation was strongly influenced by the Labrador Current and the silty muds show architecture characteristic of contourites. Variation in Labrador Current strength is known from the sortable silt proxy over the past 125 ka. Large slope failures were mapped from seismic reflection profiles and their age estimated from seismic stratigraphy (3-5 ka resolution) and in some cases refined from cores (1-3 ka resolution). Large slope failures occurred apparently synchronously over margin lengths of 50-350 km. Such failures were earthquake triggered: other mechanisms for producing laterally extensive synchronous failure do not apply. Triaxial shear measurements show a Su/σ' ratio of typical slope sediment of 0.48, implying considerable stability. However, some silty muds have Atterberg limits that suggest susceptibility to liquefaction under cyclic loading, particularly in Holocene deposits and by analogy those of past full interglacials. Basal failure planes of some large failures correspond with either the last interglacial or the MIS 6 glacial maximum. Comparison with seismological models suggests that the observed slope failures represent earthquakes ranging from Mw ~5.6 to ~7.6. Mean recurrence interval of M = 7 earthquakes at any point on the margin is estimated at 30 ka from seismological models and 40 ka from the sediment failure record. In northern Flemish Pass, a spatial cluster of several failures over 30 ka preceded by a long interval with no failures suggests that some other mechanism has

  1. Evaluation of Acoustic Emission NDE of Kevlar Composite Over Wrapped Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Horne, Michael R.; Madaras, Eric I.

    2008-01-01

    Pressurization and failure tests of small Kevlar/epoxy COPV bottles were conducted during 2006 and 2007 by Texas Research Institute Austin, Inc., at TRI facilities. This is a report of the analysis of the Acoustic Emission (AE) data collected during those tests. Results of some of the tests indicate a possibility that AE can be used to track the stress-rupture degradation of COPV vessels.

  2. Antithrombin III is associated with acute liver failure in patients with end-stage heart failure undergoing mechanical circulatory support.

    PubMed

    Hoefer, Judith; Ulmer, Hanno; Kilo, Juliane; Margreiter, Raimund; Grimm, Michael; Mair, Peter; Ruttmann, Elfriede

    2017-06-01

    There are few data on the role of liver dysfunction in patients with end-stage heart failure supported by mechanical circulatory support. The aim of our study was to investigate predictors for acute liver failure in patients with end-stage heart failure undergoing mechanical circulatory support. A consecutive 164 patients with heart failure with New York Heart Association class IV undergoing mechanical circulatory support were investigated for acute liver failure using the King's College criteria. Clinical characteristics of heart failure together with hemodynamic and laboratory values were analyzed by logistic regression. A total of 45 patients (27.4%) with heart failure developed subsequent acute liver failure with a hospital mortality of 88.9%. Duration of heart failure, cause, cardiopulmonary resuscitation, use of vasopressors, central venous pressure, pulmonary capillary wedge pressure, pulmonary pulsatility index, cardiac index, and transaminases were not significantly associated with acute liver failure. Repeated decompensation, atrial fibrillation (P < .001) and the use of inotropes (P = .007), mean arterial (P = .005) and pulmonary pressures (P = .042), cholinesterase, international normalized ratio, bilirubin, lactate, and pH (P < .001) were predictive of acute liver failure in univariate analysis only. In multivariable analysis, decreased antithrombin III was the strongest single measurement indicating acute liver failure (relative risk per %, 0.84; 95% confidence interval, 0.77-0.93; P = .001) and remained an independent predictor when adjustment for the Model for End-Stage Liver Disease score was performed (relative risk per %, 0.89; 95% confidence interval, 0.80-0.99; P = .031). Antithrombin III less than 59.5% was identified as a cutoff value to predict acute liver failure with a corresponding sensitivity of 81% and specificity of 87%. In addition to the Model for End-Stage Liver Disease score, decreased antithrombin III activity tends

  3. Weighted Fuzzy Risk Priority Number Evaluation of Turbine and Compressor Blades Considering Failure Mode Correlations

    NASA Astrophysics Data System (ADS)

    Gan, Luping; Li, Yan-Feng; Zhu, Shun-Peng; Yang, Yuan-Jian; Huang, Hong-Zhong

    2014-06-01

    Failure mode, effects and criticality analysis (FMECA) and Fault tree analysis (FTA) are powerful tools to evaluate reliability of systems. Although single failure mode issue can be efficiently addressed by traditional FMECA, multiple failure modes and component correlations in complex systems cannot be effectively evaluated. In addition, correlated variables and parameters are often assumed to be precisely known in quantitative analysis. In fact, due to the lack of information, epistemic uncertainty commonly exists in engineering design. To solve these problems, the advantages of FMECA, FTA, fuzzy theory, and Copula theory are integrated into a unified hybrid method called fuzzy probability weighted geometric mean (FPWGM) risk priority number (RPN) method. The epistemic uncertainty of risk variables and parameters are characterized by fuzzy number to obtain fuzzy weighted geometric mean (FWGM) RPN for single failure mode. Multiple failure modes are connected using minimum cut sets (MCS), and Boolean logic is used to combine fuzzy risk priority number (FRPN) of each MCS. Moreover, Copula theory is applied to analyze the correlation of multiple failure modes in order to derive the failure probabilities of each MCS. Compared to the case where dependency among multiple failure modes is not considered, the Copula modeling approach eliminates the error of reliability analysis. Furthermore, for purpose of quantitative analysis, probabilities importance weight from failure probabilities are assigned to FWGM RPN to reassess the risk priority, which generalize the definition of probability weight and FRPN, resulting in a more accurate estimation than that of the traditional models. Finally, a basic fatigue analysis case drawn from turbine and compressor blades in aeroengine is used to demonstrate the effectiveness and robustness of the presented method. The result provides some important insights on fatigue reliability analysis and risk priority assessment of structural

  4. Systolic blood pressure reduction during the first 24 h in acute heart failure admission: friend or foe?

    PubMed

    Cotter, Gad; Metra, Marco; Davison, Beth A; Jondeau, Guillaume; Cleland, John G F; Bourge, Robert C; Milo, Olga; O'Connor, Christopher M; Parker, John D; Torre-Amione, Guillermo; van Veldhuisen, Dirk J; Kobrin, Isaac; Rainisio, Maurizio; Senger, Stefanie; Edwards, Christopher; McMurray, John J V; Teerlink, John R

    2018-02-01

    Changes in systolic blood pressure (SBP) during an admission for acute heart failure (AHF), especially those leading to hypotension, have been suggested to increase the risk for adverse outcomes. We analysed associations of SBP decrease during the first 24 h from randomization with serum creatinine changes at the last time-point available (72 h), using linear regression, and with 30- and 180-day outcomes, using Cox regression, in 1257 patients in the VERITAS study. After multivariable adjustment for baseline SBP, greater SBP decrease at 24 h from randomization was associated with greater creatinine increase at 72 h and greater risk for 30-day all-cause death, worsening heart failure (HF) or HF readmission. The hazard ratio (HR) for each 1 mmHg decrease in SBP at 24 h for 30-day death, worsening HF or HF rehospitalization was 1.01 [95% confidence interval (CI) 1.00-1.02; P = 0.021]. Similarly, the HR for each 1 mmHg decrease in SBP at 24 h for 180-day all-cause mortality was 1.01 (95% CI 1.00-1.03; P = 0.038). The associations between SBP decrease and outcomes did not differ by tezosentan treatment group, although tezosentan treatment was associated with a greater SBP decrease at 24 h. In the current post hoc analysis, SBP decrease during the first 24 h was associated with increased renal impairment and adverse outcomes at 30 and 180 days. Caution, with special attention to blood pressure monitoring, should be exercised when vasodilating agents are given to AHF patients. © 2017 The Authors. European Journal of Heart Failure © 2017 European Society of Cardiology.

  5. Worsening renal function definition is insufficient for evaluating acute renal failure in acute heart failure.

    PubMed

    Shirakabe, Akihiro; Hata, Noritake; Kobayashi, Nobuaki; Okazaki, Hirotake; Matsushita, Masato; Shibata, Yusaku; Nishigoori, Suguru; Uchiyama, Saori; Asai, Kuniya; Shimizu, Wataru

    2018-06-01

    Whether or not the definition of a worsening renal function (WRF) is adequate for the evaluation of acute renal failure in patients with acute heart failure is unclear. One thousand and eighty-three patients with acute heart failure were analysed. A WRF, indicated by a change in serum creatinine ≥0.3 mg/mL during the first 5 days, occurred in 360 patients while no-WRF, indicated by a change <0.3 mg/dL, in 723 patients. Acute kidney injury (AKI) upon admission was defined based on the ratio of the serum creatinine value recorded on admission to the baseline creatinine value and placed into groups based on the degree of AKI: no-AKI (n = 751), Class R (risk; n = 193), Class I (injury; n = 41), or Class F (failure; n = 98). The patients were assigned to another set of four groups: no-WRF/no-AKI (n = 512), no-WRF/AKI (n = 211), WRF/no-AKI (n = 239), and WRF/AKI (n = 121). A multivariate logistic regression model found that no-WRF/AKI and WRF/AKI were independently associated with 365 day mortality (hazard ratio: 1.916; 95% confidence interval: 1.234-2.974 and hazard ratio: 3.622; 95% confidence interval: 2.332-5.624). Kaplan-Meier survival curves showed that the rate of any-cause death during 1 year was significantly poorer in the no-WRF/AKI and WRF/AKI groups than in the WRF/no-AKI and no-WRF/no-AKI groups and in Class I and Class F than in Class R and the no-AKI group. The presence of AKI on admission, especially Class I and Class F status, is associated with a poor prognosis despite the lack of a WRF within the first 5 days. The prognostic ability of AKI on admission may be superior to WRF within the first 5 days. © 2018 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.

  6. Dynamic wetting failure in surfactant solutions

    NASA Astrophysics Data System (ADS)

    Liu, Chen-Yu; Vandre, Eric; Carvalho, Marcio; Kumar, Satish

    2015-11-01

    The influence of insoluble surfactants on dynamic wetting failure during displacement of Newtonian fluids in a rectangular channel is studied in this work. A hydrodynamic model for steady Stokes flows of dilute surfactant solutions is developed and evaluated using three approaches: (i) a one-dimensional (1D) lubrication-type approach, (ii) a novel hybrid of a 1D description of the receding phase and a 2D description of the advancing phase, and (iii) an asymptotic theory of Cox. Steady-state solution families in the form of macroscopic contact angles as a function of the capillary number are determined and limit points are identified. When air is the receding fluid, Marangoni stresses are found to increase the receding-phase pressure gradients near the contact line by thinning the air film without significantly changing the capillary-pressure gradients there. As consequence, the limit points shift to lower capillary numbers and the onset of wetting failure is promoted. The model predictions are then used to interpret decades-old experimental observations concerning the influence of surfactants on air entrainment. The hybrid modeling approach developed here can readily be extended to more complicated geometries where a thin air layer is present near a contact line.

  7. Prognostic value of noninvasive hemodynamic evaluation of the acute effect of levosimendan in advanced heart failure.

    PubMed

    Malfatto, Gabriella; Della Rosa, Francesco; Rella, Valeria; Villani, Alessandra; Branzi, Giovanna; Blengino, Simonetta; Giglio, Alessia; Facchini, Mario; Parati, Gianfranco

    2014-04-01

    Optimization of inotropic treatment in worsening heart failure sometimes requires invasive hemodynamic assessment in selected patients. Impedance cardiography (ICG) may be useful for a noninvasive hemodynamic evaluation. ICG was performed in 40 patients (69 ± 8 years; left ventricular ejection fraction 27.5 ± 5.6%; New York Heart Association 3.18 ± 0.34; Interagency Registry for Mechanically Assisted Circulatory Support 5.48 ± 0.96, before and after infusion of Levosimendan (0.1–0.2 µg/kg per min for up to 24 h). Echocardiogram, ICG [measuring cardiac index (CI), total peripheral resistances (TPRs) and thoracic fluid content (TFC)] and plasma levels of brain natriuretic peptide (BNP) were obtained; in nine patients, right heart catheterization was also carried out. When right catheterization and ICG were performed simultaneously, a significant relationship was observed between values of CI and TPR, and between TFC and pulmonary wedge pressure. ICG detected the Levosimendan-induced recovery of the hemodynamic status, associated with improved systolic and diastolic function and reduction in BNP levels. One-year mortality was 4.4%. At multivariate analysis, independent predictors of mortality were: no improvement in the severity of mitral regurgitation, a persistent restrictive filling pattern (E/E’ > 15), a reduction of BNP levels below 30% and a change below 10% in CI, TPR and TFC. When combined, absence of hemodynamic improvement at ICG could predict 1-year mortality with better sensitivity (86%) and specificity (85%) than the combination of echocardiographic and BNP criteria only (sensitivity 80% and specificity 36%). Noninvasive hemodynamic evaluation of heart failure patients during infusion of inodilator drugs is reliable and may help in their prognostic stratification.

  8. Evaluating the Phoenix definition of biochemical failure after (125)I prostate brachytherapy: Can PSA kinetics distinguish PSA failures from PSA bounces?

    PubMed

    Thompson, Anna; Keyes, Mira; Pickles, Tom; Palma, David; Moravan, Veronika; Spadinger, Ingrid; Lapointe, Vincent; Morris, W James

    2010-10-01

    To evaluate the prostate-specific antigen (PSA) kinetics of PSA failure (PSAf) and PSA bounce (PSAb) after permanent (125)I prostate brachytherapy (PB). The study included 1,006 consecutive low and "low tier" intermediate-risk patients treated with (125)I PB, with a potential minimum follow-up of 4 years. Patients who met the Phoenix definition of biochemical failure (nadir + 2 ng/mL(-1)) were identified. If the PSA subsequently fell to ≤0.5 ng/mL(-1)without intervention, this was considered a PSAb. All others were scored as true PSAf. Patient, tumor and dosimetric characteristics were compared between groups using the chi-square test and analysis of variance to evaluate factors associated with PSAf or PSAb. Median follow-up was 54 months. Of the 1,006 men, 57 patients triggered the Phoenix definition of PSA failure, 32 (56%) were true PSAf, and 25 PSAb (44%). The median time to trigger nadir + 2 was 20.6 months (range, 6-36) vs. 49 mo (range, 12-83) for PSAb vs. PSAf groups (p < 0.001). The PSAb patients were significantly younger (p < 0.0001), had shorter time to reach the nadir (median 6 vs. 11.5 months, p = 0.001) and had a shorter PSA doubling time (p = 0.05). Men younger than age 70 who trigger nadir +2 PSA failure within 38 months of implant have an 80% likelihood of having PSAb and 20% chance of PSAf. With adequate follow-up, 44% of PSA failures by the Phoenix definition in our cohort were found to be benign PSA bounces. Our study reinforces the need for adequate follow-up when reporting PB PSA outcomes, to ensure accurate estimates of treatment efficacy and to avoid unnecessary secondary interventions. 2010. Published by Elsevier Inc. All rights reserved.

  9. Fuzzy Risk Evaluation in Failure Mode and Effects Analysis Using a D Numbers Based Multi-Sensor Information Fusion Method.

    PubMed

    Deng, Xinyang; Jiang, Wen

    2017-09-12

    Failure mode and effect analysis (FMEA) is a useful tool to define, identify, and eliminate potential failures or errors so as to improve the reliability of systems, designs, and products. Risk evaluation is an important issue in FMEA to determine the risk priorities of failure modes. There are some shortcomings in the traditional risk priority number (RPN) approach for risk evaluation in FMEA, and fuzzy risk evaluation has become an important research direction that attracts increasing attention. In this paper, the fuzzy risk evaluation in FMEA is studied from a perspective of multi-sensor information fusion. By considering the non-exclusiveness between the evaluations of fuzzy linguistic variables to failure modes, a novel model called D numbers is used to model the non-exclusive fuzzy evaluations. A D numbers based multi-sensor information fusion method is proposed to establish a new model for fuzzy risk evaluation in FMEA. An illustrative example is provided and examined using the proposed model and other existing method to show the effectiveness of the proposed model.

  10. Fuzzy Risk Evaluation in Failure Mode and Effects Analysis Using a D Numbers Based Multi-Sensor Information Fusion Method

    PubMed Central

    Deng, Xinyang

    2017-01-01

    Failure mode and effect analysis (FMEA) is a useful tool to define, identify, and eliminate potential failures or errors so as to improve the reliability of systems, designs, and products. Risk evaluation is an important issue in FMEA to determine the risk priorities of failure modes. There are some shortcomings in the traditional risk priority number (RPN) approach for risk evaluation in FMEA, and fuzzy risk evaluation has become an important research direction that attracts increasing attention. In this paper, the fuzzy risk evaluation in FMEA is studied from a perspective of multi-sensor information fusion. By considering the non-exclusiveness between the evaluations of fuzzy linguistic variables to failure modes, a novel model called D numbers is used to model the non-exclusive fuzzy evaluations. A D numbers based multi-sensor information fusion method is proposed to establish a new model for fuzzy risk evaluation in FMEA. An illustrative example is provided and examined using the proposed model and other existing method to show the effectiveness of the proposed model. PMID:28895905

  11. Determinants of the development of mitral regurgitation in pacing-induced heart failure.

    PubMed

    Takagaki, Masami; McCarthy, Patrick M; Goormastic, Marlene; Ochiai, Yoshie; Doi, Kazuyoshi; Kopcak, Michael W; Tabata, Tomotsugu; Cardon, Lisa A; Thomas, James D; Fukamachi, Kiyotaka

    2003-01-01

    The pacing-induced heart failure model provides an opportunity to assess the structural and functional determinants of mitral regurgitation (MR) in dilated cardiomyopathy. This study aimed to evaluate MR to better understand the multitude of factors contributing to its development. Heart failure was induced by rapid ventricular pacing (230 beats/min) in 40 mongrel dogs. Left ventricular (LV) size and MR were evaluated echocardiographically. LV contractility was analyzed using a conductance catheter. MR increased to mild in 12 animals (regurgitant orifice area, 0.06+/-0.05 cm(2)), moderate in 15 (0.14+/-0.07 cm(2)), and severe in 13 (0.34+/-0.16 cm(2)). The grade of MR had an inverse relationships with E(max) (the slope of the end-systolic pressure-volume relationship, p<0.01) and dE/dt (the slope of the maximum rate of change of pressure-end-diastolic volume [V(ED)] relationship, p<0.01) and positive relationships with V(ED) and end-diastolic cross-sectional areas and lengths (p<0.05) by univariate analysis. The dE/dt had an independently significant (p<0.01) relationship by multivariable logistic regression. Many factors influence the development of MR and because of its similarity to the clinical situation, this model can be used to investigate MR and heart failure, as well as new surgical therapies.

  12. Stress analysis and evaluation of a rectangular pressure vessel

    NASA Astrophysics Data System (ADS)

    Rezvani, M. A.; Ziada, H. H.; Shurrab, M. S.

    1992-10-01

    This study addresses structural analysis and evaluation of an abnormal rectangular pressure vessel, designed to house equipment for drilling and collecting samples from Hanford radioactive waste storage tanks. It had to be qualified according to ASME boiler and pressure vessel code, section 8; however, it had the cover plate bolted along the long face, a configuration not addressed by the code. Finite element method was used to calculate stresses resulting from internal pressure; these stresses were then used to evaluate and qualify the vessel. Fatigue is not a concern; thus, it can be built according to section 8, division 1 instead of division 2. Stress analysis was checked against the code. A stayed plate was added to stiffen the long side of the vessel.

  13. Subatmospheric vapor pressures evaluated from internal-energy measurements

    NASA Astrophysics Data System (ADS)

    Duarte-Garza, H. A.; Magee, J. W.

    1997-01-01

    Vapor pressures were evaluated from measured internal-energy changes in the vapor+liquid two-phase region, Δ U (2). The method employed a thermodynamic relationship between the derivative quantity (ϖ U (2)/ϖ V) T and the vapor pressure ( p σ) and its temperature derivative (ϖ p/ϖ T)σ. This method was applied at temperatures between the triple point and the normal boiling point of three substances: 1,1,1,2-tetrafluoroethane (R134a), pentafluoroethane (R125), and difluoromethane (R32). Agreement with experimentally measured vapor pressures near the normal boiling point (101.325 kPa) was within the experimental uncertainty of approximately ±0.04 kPa (±0.04%). The method was applied to R134a to test the thermodynamic consistency of a published p-p-T equation of state with an equation for p σ for this substance. It was also applied to evaluate published p σ data which are in disagreement by more than their claimed uncertainty.

  14. [Comorbidities of heart failure: sleep apnea].

    PubMed

    Woehrle, H; Oldenburg, O; Stadler, S; Arzt, M

    2018-05-01

    Since sleep apnea often occurs in heart failure, physicians regularly need to decide whether further diagnostic procedures and/or treatment are required. Which types of sleep apnea occur in heart failure patients? When is treatment needed? Which treatments and treatment goals are appropriate? Clinical trials and guidelines as well as their implementation in clinical practice are discussed. At least 40% of patients with heart failure, both with reduced and preserved left ventricular ejection fraction (HFrEF and HFpEF, respectively), suffer from relevant sleep apnea. In heart failure patients both obstructive and central sleep apnea are associated with increased mortality. In HFrEF as well as in HFpEF patients with obstructive sleep apnea, treatment with continuous positive airway pressure (CPAP) achieves symptomatic and functional improvements. In patients with HFpEF, positive airway pressure treatment of central sleep apnea may be beneficial. In patients with HFrEF and left ventricular ejection fraction ≤45%, adaptive servoventilation is contraindicated. Sleep apnea is highly prevalent in heart failure patients and its treatment in specific patient groups can improve symptoms and functional outcomes. Thus, testing for sleep apnea is recommended.

  15. Worsening renal function definition is insufficient for evaluating acute renal failure in acute heart failure

    PubMed Central

    Hata, Noritake; Kobayashi, Nobuaki; Okazaki, Hirotake; Matsushita, Masato; Shibata, Yusaku; Nishigoori, Suguru; Uchiyama, Saori; Asai, Kuniya; Shimizu, Wataru

    2018-01-01

    Abstract Aims Whether or not the definition of a worsening renal function (WRF) is adequate for the evaluation of acute renal failure in patients with acute heart failure is unclear. Methods and results One thousand and eighty‐three patients with acute heart failure were analysed. A WRF, indicated by a change in serum creatinine ≥0.3 mg/mL during the first 5 days, occurred in 360 patients while no‐WRF, indicated by a change <0.3 mg/dL, in 723 patients. Acute kidney injury (AKI) upon admission was defined based on the ratio of the serum creatinine value recorded on admission to the baseline creatinine value and placed into groups based on the degree of AKI: no‐AKI (n = 751), Class R (risk; n = 193), Class I (injury; n = 41), or Class F (failure; n = 98). The patients were assigned to another set of four groups: no‐WRF/no‐AKI (n = 512), no‐WRF/AKI (n = 211), WRF/no‐AKI (n = 239), and WRF/AKI (n = 121). A multivariate logistic regression model found that no‐WRF/AKI and WRF/AKI were independently associated with 365 day mortality (hazard ratio: 1.916; 95% confidence interval: 1.234–2.974 and hazard ratio: 3.622; 95% confidence interval: 2.332–5.624). Kaplan–Meier survival curves showed that the rate of any‐cause death during 1 year was significantly poorer in the no‐WRF/AKI and WRF/AKI groups than in the WRF/no‐AKI and no‐WRF/no‐AKI groups and in Class I and Class F than in Class R and the no‐AKI group. Conclusions The presence of AKI on admission, especially Class I and Class F status, is associated with a poor prognosis despite the lack of a WRF within the first 5 days. The prognostic ability of AKI on admission may be superior to WRF within the first 5 days. PMID:29388735

  16. Comparison of plasma B-type natriuretic peptide levels in single ventricle patients with systemic ventricle heart failure versus isolated cavopulmonary failure.

    PubMed

    Law, Yuk Ming; Ettedgui, Jose; Beerman, Lee; Maisel, Alan; Tofovic, Stevan

    2006-08-15

    The measurement of plasma B-type natriuretic peptide (BNP) has emerged as a useful biomarker of heart failure in patients with cardiomyopathy. The pathophysiology of heart failure in single ventricle (SV) circulation may be distinct from that of cardiomyopathies. A distinct pattern of BNP elevation in heart failure in the SV population was hypothesized: it is elevated in heart failure secondary to ventricular dysfunction but not in isolated cavopulmonary failure. BNP was measured prospectively in SV patients at catheterization (n = 22) and when assessing for heart failure (n = 11) (7 normal controls). Of 33 SV subjects (median age 62 months), 13 had aortopulmonary connections and 20 had cavopulmonary connections. Median and mean +/- SD BNP levels by shunt type were 184 and 754 +/- 1,086 pg/ml in the patients with aortopulmonary connections, 38 and 169 +/- 251 pg/ml in the patients with cavopulmonary connections, and 10 and 11 +/- 5 pg/ml in normal controls, respectively (p = 0.004). Median systemic ventricular end-diastolic pressure (8mm Hg, R = 0.45), mean pulmonary artery pressure (14.5 mm Hg, R = 0.62), and mean right atrial pressure (6.5 mm Hg, R = 0.54) were correlated with plasma BNP. SV subjects with symptomatic heart failure from dysfunctional systemic ventricles had median and mean +/- SD BNP levels of 378 and 714 +/- 912 pg/ml (n = 18) compared with patients with isolated failed Glenn or Fontan connections (19 and 23 +/- 16 pg/ml [n = 7, p = 0.001]) and those with no heart failure (22 and 22 +/- 12 pg/ml [n = 8, p = 0.001]). Excluding the group with cavopulmonary failure, the severity of heart failure from systemic ventricular dysfunction was associated with plasma BNP. In conclusion, plasma BNP is elevated in SV patients with systemic ventricular or left-sided cardiac failure. BNP is not elevated in patients missing a pulmonary ventricle with isolated cavopulmonary failure.

  17. Evaluation of the concept of pressure proof testing fuselage structures

    NASA Technical Reports Server (NTRS)

    Harris, Charles E.; Orringer, Oscar

    1991-01-01

    The FAA and NASA have recently completed independent technical evaluations of the concept of pressure proof testing the fuselage of commercial transport airplanes. The results of these evaluations are summarized. The objectives of the evaluations were to establish the potential benefit of the pressure proof test, to quantify the most desirable proof test pressure, and to quantify the required proof test interval. The focus of the evaluations was on multiple-site cracks extending from adjacent rivet holes of a typical fuselage longitudinal lap splice joint. The FAA and NASA do not support pressure proof testing the fuselage of aging commercial transport aircraft. The argument against proof testing is as follows: (1) a single proof test does not insure an indefinite life; therefore, the proof test must be repeated at regular intervals; (2) for a proof factor of 1.33, the required proof test interval must be below 300 flights to account for uncertainties in the evaluation; (3) conducting the proof test at a proof factor of 1.5 would considerably exceed the fuselage design limit load; therefore, it is not consistent with accepted safe practices; and (4) better safety can be assured by implementing enhanced nondestructive inspection requirements, and adequate reliability can be achieved by an inspection interval several times longer than the proof test interval.

  18. Acute Right Ventricle Failure in the Intensive Care Unit: Assessment and Management.

    PubMed

    Hrymak, Carmen; Strumpher, Johann; Jacobsohn, Eric

    2017-01-01

    Caring for the critically ill patient with acute right ventricle (RV) failure is a diagnostic and management challenge. A thorough understanding of normal RV anatomy and physiology is essential to manage RV failure. Despite the fact that the RV is essentially a volume chamber that ejects into a low-pressure system, the left ventricle contributes significantly to RV function through maintenance of the transseptal gradient (TSG). Preserving systemic mean arterial pressure maintains the TSG and RV perfusion. Various pathological states cause acute RV failure by decreasing the TSG and RV perfusion and/or increasing pulmonary vascular resistance. Early diagnosis prevents rapid progression of RV failure due to the "double hit phenomenon," which is acute intra-abdominal multiple organ system failure as a result of a reduced blood pressure and elevated central venous pressure. Management includes hemodynamic support and reversal of the precipitating cause through optimizing RV rate and rhythm, determining ideal RV filling pressure, reducing RV afterload through nonpharmacologic and pharmacological means, and selecting the appropriate RV inotrope or mechanical support. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  19. The coagulopathy of acute liver failure and implications for intracranial pressure monitoring.

    PubMed

    Munoz, Santiago J; Rajender Reddy, K; Lee, William

    2008-01-01

    The development of coagulopathy in acute liver failure (ALF) is universal. The severity of the coagulopathy is often assessed by determination of the prothrombin time and International Normalized Ratio (INR). In more than 1,000 ALF cases, the severity of the coagulopathy was moderate in 81% (INR 1.5-5.0), severe in 14% (INR 5.0-10.0), and very severe in 5% (INR > 10.0). Certain etiologies were associated with more severe coagulopathy, whereas ALF caused by fatty liver of pregnancy had the least severe coagulopathy. Management consisted of transfusions of FFP in 92%. Overall, FFP administered during the first week of admission amounted to 13.7 +/- 15 units. Patients who received an ICP monitor had significantly more FFP transfused than those managed without ICP monitor (22.7 +/- 2.4 vs. 12.3 +/- 0.8 units FFP; P < 0.001). Only a minority of patients developed gastrointestinal bleeding or had an intracranial pressure monitor installed. Further research is necessary to explore the reasons clinicians transfuse ALF patients with large amounts of FFP in the absence of active bleeding or invasive procedures.

  20. Failure detection and fault management techniques for flush airdata sensing systems

    NASA Technical Reports Server (NTRS)

    Whitmore, Stephen A.; Moes, Timothy R.; Leondes, Cornelius T.

    1992-01-01

    Methods based on chi-squared analysis are presented for detecting system and individual-port failures in the high-angle-of-attack flush airdata sensing system on the NASA F-18 High Alpha Research Vehicle. The HI-FADS hardware is introduced, and the aerodynamic model describes measured pressure in terms of dynamic pressure, angle of attack, angle of sideslip, and static pressure. Chi-squared analysis is described in the presentation of the concept for failure detection and fault management which includes nominal, iteration, and fault-management modes. A matrix of pressure orifices arranged in concentric circles on the nose of the aircraft indicate the parameters which are applied to the regression algorithms. The sensing techniques are applied to the F-18 flight data, and two examples are given of the computed angle-of-attack time histories. The failure-detection and fault-management techniques permit the matrix to be multiply redundant, and the chi-squared analysis is shown to be useful in the detection of failures.

  1. Fracture strength of flawed cylindrical pressure vessels under cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Christopher, T.; Sankarnarayanasamy, K.; Nageswara Rao, B.

    2002-11-01

    Damage tolerant and fail-safe approaches have been employed increasingly in the design of critical engineering components. In these approaches, one has to assess the residual strength of a component with an assumed pre-existing crack. In other cases, cracks may be detected during service. Then, there is a need to evaluate the residual strength of the cracked components in order to decide whether they can be continued safely or repair and replacement are imperative. A three-parameter fracture criterion is applied to correlate the fracture data on aluminium, titanium and steel materials from test results on cylindrical tanks/pressure vessels at cryogenic temperatures. Fracture parameters to generate the failure assessment diagram are determined for the materials considered in the present study. Failure pressure estimates were found to be in good agreement with test results.

  2. Cavitation Inside High-Pressure Optically Transparent Fuel Injector Nozzles

    NASA Astrophysics Data System (ADS)

    Falgout, Z.; Linne, M.

    2015-12-01

    Nozzle-orifice flow and cavitation have an important effect on primary breakup of sprays. For this reason, a number of studies in recent years have used injectors with optically transparent nozzles so that orifice flow cavitation can be examined directly. Many of these studies use injection pressures scaled down from realistic injection pressures used in modern fuel injectors, and so the geometry must be scaled up so that the Reynolds number can be matched with the industrial applications of interest. A relatively small number of studies have shown results at or near the injection pressures used in real systems. Unfortunately, neither the specifics of the design of the optical nozzle nor the design methodology used is explained in detail in these papers. Here, a methodology demonstrating how to prevent failure of a finished design made from commonly used optically transparent materials will be explained in detail, and a description of a new design for transparent nozzles which minimizes size and cost will be shown. The design methodology combines Finite Element Analysis with relevant materials science to evaluate the potential for failure of the finished assembly. Finally, test results imaging a cavitating flow at elevated pressures are presented.

  3. Beta-erythropoietin effects on ventricular remodeling, left and right systolic function, pulmonary pressure, and hospitalizations in patients affected with heart failure and anemia.

    PubMed

    Palazzuoli, Alberto; Silverberg, Donald S; Calabrò, Anna; Spinelli, Tommaso; Quatrini, Ilaria; Campagna, Maria S; Franci, Beatrice; Nuti, Ranuccio

    2009-06-01

    Anemia in heart failure is related to advanced New York Heart Association classes, severe systolic dysfunction, and reduced exercise tolerance. Although anemia is frequently found in congestive heart failure (CHF), little is known about the effect of its' correction with erythropoietin (EPO) on cardiac structure and function. The present study examines, in patients with advanced CHF and anemia, the effects of beta-EPO on left ventricular volumes, left ventricular ejection fraction (LVEF), left and right longitudinal function mitral anular plane systolic excursion (MAPSE), tricuspid anular plane excursion (TAPSE), and pulmonary artery pressures in 58 patients during 1-year follow-up in a double-blind controlled study of correction of anemia with subcutaneous beta-EPO. Echocardiographic evaluation, B-Type natriuretic peptide (BNP) levels, and hematological parameters are reported at 4 and 12 months. The patients in group A after 4 months of follow-up period demonstrated an increase in LVEF and MAPSE (P < 0.05 and P < 0.01, respectively) with left ventricular systolic volume reduction (P < 0.02) with respect to baseline and controls. After 12 months, results regarding left ventricular systolic volume LVEF and MAPSE persisted (P < 0.001). In addition, TAPSE increased and pulmonary artery pressures fell significantly in group A (P < 0.01). All these changes occurred together with a significant BNP reduction and significant hemoglobin increase in the treated group. Therefore, we revealed a reduced hospitalization rate in treated patients with respect to the controls (25% in treated vs. 54% in controls). In patients with anemia and CHF, correction of anemia with beta-EPO and oral iron over 1 year leads to an improvement in left and right ventricular systolic function by reducing cardiac remodeling, BNP levels, and hospitalization rate.

  4. Development of a Numerical Model of Hypervelocity Impact into a Pressurized Composite Overwrapped Pressure Vessel

    NASA Technical Reports Server (NTRS)

    Garcia, M. A.; Davis, B. A.; Miller, J. E.

    2017-01-01

    considered a catastrophic failure. This assumption is conservative and made due to lack of knowledge on the level of allow-able damage to the composite overwrap that can be sustained and still allow successful completion of the mission. To quantify the allowable damage level to the composite overwrap involves assessing stress redistribution following damage as well as evaluating possible time-dependent mechanisms involved in the COPV response to an impact event. Limited published work in this subject has shown that COPV can withstand at least some level of damage due to high energy impacts. These observations have been confirmed and expanded upon in recent experimental research performed by NASA. This research has demonstrated that there is not only robustness in a COPV to compensate for CFRP damage, but has also identified two significant failure modes for pressurized COPV. The lowest threshold failure mode involves the perforation of the vessel, and the highest threshold failure mode is the catastrophic rupture. While both of these failure modes mean a loss of the COPV, system robustness affords some tolerance to the venting as opposed to the more catastrophic rupture. As a consequence, it is necessary to understand the conditions that result in the transition between these failure modes. The aforementioned experimental research has been performed in both the unpressurized and pressurized condition to identify the damage level that triggered the failure thresh-old. This COPV test program was sponsored by the NASA Engineering and Safety Center (NESC), and tests were performed at NASA White Sands Test Facility (WSTF). Planning and coordination were provided by NASA JSC Hypervelocity Impact Technology (HVIT) group, and the COPVs were provided by the ISS Program. Unpressurized testing has been conducted at the pressure of the vacuum test chamber, while, the pressurized testing has been conducted at 290 +/- 10 bar (4,200 ? 100 psi) using nitrogen as the pressurizing gas, which

  5. Molecular Mechanisms of Right Ventricular Failure

    PubMed Central

    Reddy, Sushma; Bernstein, Daniel

    2015-01-01

    An abundance of data has provided insight into the mechanisms underlying the development of left ventricular (LV) hypertrophy and its progression to LV failure. In contrast, there is minimal data on the adaptation of the right ventricle (RV) to pressure and volume overload and the transition to RV failure. This is a critical clinical question, as the RV is uniquely at risk in many patients with repaired or palliated congenital heart disease and in those with pulmonary hypertension. Standard heart failure therapies have failed to improve function or survival in these patients, suggesting a divergence in the molecular mechanisms of RV vs. LV failure. Although, on the cellular level, the remodeling responses of the RV and LV to pressure overload are largely similar, there are several key differences: the stressed RV is more susceptible to oxidative stress, has a reduced angiogenic response, and is more likely to activate cell death pathways than the stressed LV. Together, these differences could explain the more rapid progression of the RV to failure vs. the LV. This review will highlight known molecular differences between the RV and LV responses to hemodynamic stress, the unique stressors on the RV associated with congenital heart disease, and the need to better understand these molecular mechanisms if we are to develop RV-specific heart failure therapeutics. PMID:26527692

  6. Porting Inition and Failure to Linked Cheetah

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vitello, P; Souers, P C

    2007-07-18

    Linked CHEETAH is a thermo-chemical code coupled to a 2-D hydrocode. Initially, a quadratic-pressure dependent kinetic rate was used, which worked well in modeling prompt detonation of explosives of large size, but does not work on other aspects of explosive behavior. The variable-pressure Tarantula reactive flow rate model was developed with JWL++ in order to also describe failure and initiation, and we have moved this model into Linked CHEETAH. The model works by turning on only above a pressure threshold, where a slow turn-on creates initiation. At a higher pressure, the rate suddenly leaps to a large value over amore » small pressure range. A slowly failing cylinder will see a rapidly declining rate, which pushes it quickly into failure. At a high pressure, the detonation rate is constant. A sequential validation procedure is used, which includes metal-confined cylinders, rate-sticks, corner-turning, initiation and threshold, gap tests and air gaps. The size (diameter) effect is central to the calibration.« less

  7. The evaluation of the effect of body positioning on intra-abdominal pressure measurement and the effect of intra-abdominal pressure at different body positioning on organ function and prognosis in critically ill patients.

    PubMed

    Yi, Min; Leng, Yuxin; Bai, Yu; Yao, Gaiqi; Zhu, Xi

    2012-04-01

    Current literatures confirmed the widespread and frequent development of both intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) among the critically ill with a significant associated risk of organ failure and increased mortality. The 2004 International ACS Consensus Conference committee proposed that intra-abdominal pressure (IAP) be measured in complete supine position; however, the supine position of intensive care unit (ICU) patients (<30° of bed increase) presented a significant risk for ventilator-associated pneumonia. Therefore, the potential contribution of head of bed (HOB) position in elevating IAP should be considered. The purpose of this study was to evaluate the effect of body positioning on IAP measurement and the effect of IAP at different body positions on organ function and prognosis in critically ill patients. A prospective cohort study to investigate the effect of different patient positioning on IAP, organ function, and prognosis was conducted on 88 patients admitted to a medical-surgical ICU. On admission, patients' epidemiological data and risk factors for IAH were studied; daily mean IAPs, abdominal perfusion pressure, filtration gradient, Acute Physiology and Chronic Health Evaluation II score, sequential organ failure assessment score, and multiple organ dysfunction scores were registered; next, conventional hemodynamic variables, intrathoracic blood volume index, global end-diastolic volume index and extravascular lung water using the pulse contour cardiac output system were recorded. Intra-abdominal pressures were recorded through a bladder catheter every 4 hours on the first day. Intra-abdominal pressure was measured with the patient HOB increases from 0° to 45°. Mean arterial pressure was recorded simultaneously, whereas abdominal perfusion pressure and filtration gradient (FG) were also calculated simultaneously. The main results of this study were the incidence of IAH (28.4%) and ACS (2.3%) in ICU patients

  8. Slope failures evaluation and landslides investigation using 2-D resistivity method

    NASA Astrophysics Data System (ADS)

    Nordiana, M. M.; Azwin, I. N.; Nawawi, M. N. M.; Khalil, A. E.

    2018-06-01

    Slope failure is a complex phenomenon that may caused to landslides. Buildings and infrastructure such as transportation facilities and pipelines located within the boundaries of a landslide can be damaged or destroyed. Slope failure classification and various factors contributing to the instability using 2-D resistivity survey conducted in Selangor, Malaysia are described. Six 2-D resistivity survey lines with 5 m minimum electrode spacing using Pole-dipole array were performed. The data were processed using Res2Dinv and surfer10 software to evaluate the subsurface characteristics. The 2-D resistivity results show that the subsurface consist of two main zones. The first zone was alluvium or highly weathered with resistivity value of 100-1000 Ω m and depth of >30 m. This zone consists of saturated area with resistivity value of 1-100 Ω m and boulders with resistivity value of 1200-7000 Ω m. The second zone with resistivity value of >7000 Ω m was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. This will cause to low strength of soil, debris flow and movement of earth. On the basis of the case examples described, 2-D resistivity method is categorized into desirable and useful method in determination of slope failure and future assessments.

  9. Bi-level positive airway pressure ventilation for treating heart failure with central sleep apnea that is unresponsive to continuous positive airway pressure.

    PubMed

    Dohi, Tomotaka; Kasai, Takatoshi; Narui, Koji; Ishiwata, Sugao; Ohno, Minoru; Yamaguchi, Tetsu; Momomura, Shin-Ichi

    2008-07-01

    Cheyne-Stokes respiration with central sleep apnea (CSR-CSA) is associated with a poor prognosis in patients with heart failure (HF). However, some patients do not respond to continuous positive airway pressure (CPAP), so other therapeutic modalities should be considered, such as bi-level positive airway pressure (PAP), which also assists respiration and might be effective for such patients. The 20 patients with HF because of left ventricular systolic dysfunction were assessed: 8 had ischemic etiology, and all had severe CSA according to the apnea - hypopnea index (AHI) determined by polysomnography. All diagnosed patients underwent repeat polysomnography using CPAP. The AHI improved significantly in 11 (AHI <15), but only slightly in 9, in whom the AHI remained high (>or=15). Bi-level PAP titration significantly improved the AHI in the latter group. Those who were unresponsive to CPAP had significantly lower PaCO(2), higher plasma brain natriuretic peptide (BNP), longer mean duration of CSR and fewer obstructive episodes than CPAP responders. After 6 months of positive airway support with either CPAP (n=9) or bi-level PAP (n=7), BNP levels significantly decreased and left ventricular ejection fraction significantly increased. Bi-level PAP could be an effective alternative for patients with HF and pure CSR-CSA who are unresponsive to CPAP.

  10. Continuous monitoring of intracranial pressure after endoscopic third ventriculostomy in the management of CSF shunt failure.

    PubMed

    Elgamal, E A

    2010-04-01

    The effectiveness of continuous intracranial pressure (ICP) monitoring in the adaptation period, after endoscopic third ventriculostomy (ETV), and removal of the failed shunt in the management of CSF shunt failure is assessed. Nine patients with active hydrocephalus presenting with CSF shunt obstruction or infection were managed by ETV, removal of the shunt and insertion of an external ventricular drain (EVD) containing an ICP sensor for the purpose of postoperative monitoring of the ICP, and intermittent drainage of CSF. Patient ages ranged from 8 months to 24 years, and six of them were females. Hydrocephalus was obstructive in seven patients, and multiloculated in two. Six patients had an ventriculoperitoneal shunt (VPS), one with a bilateral VPS, one patient had a ventriculoatrial shunt, and one had a VPS and cystoperitoneal shunt (CPS). Shunt failure was caused by obstruction in six patients and infection in three. The post-operative ICP monitoring period ranged from 1-7 days. Intracranial hypertension was persistent in the first day after ETV in 3 patients, and up to 110 mL of CSF were drained to improve its symptoms. ETV was successful in six patients and 3 had permanent VPS. Post-operative continuous ICP monitoring and EVD insertion were very useful in the treatment of CSF shunt failure with ETV. This procedure allowed intermittent CSF drainage, relieving symptoms of elevated ICP, and provided accurate assessment of the success of the ETV and patency of the stoma in the early postoperative days by CT ventriculography and can also be used to install antibiotics in cases of infection.

  11. Influence of pretreatment systolic blood pressure on the effect of carvedilol in patients with severe chronic heart failure: the Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS) study.

    PubMed

    Rouleau, Jean L; Roecker, Ellen B; Tendera, Michal; Mohacsi, Paul; Krum, Henry; Katus, Hugo A; Fowler, Michael B; Coats, Andrew J S; Castaigne, Alain; Scherhag, Armin; Holcslaw, Terry L; Packer, Milton

    2004-04-21

    We sought to evaluate the influence of pretreatment systolic blood pressure (SBP) on the efficacy and safety of carvedilol in patients with chronic heart failure (CHF). Although beta-blockers reduce the risk of death in CHF, there is little reported experience with these drugs in patients with a low pretreatment SBP, who may respond poorly to beta-blockade. We studied 2,289 patients with severe CHF who participated in the Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS) trial. Compared with placebo, carvedilol improved the clinical status and reduced the risk of death and the combined risk of death or hospitalization for any reason, for a cardiovascular reason, or for worsening heart failure (p < 0.001 for all). The relative magnitude of these benefits did not vary as a function of the pretreatment SBP (all interaction: p > 0.10). However, because patients with the lowest SBP were at highest risk of an event, they experienced the greatest absolute benefit from treatment with carvedilol. The lower the pretreatment SBP, the more likely that patients would report an adverse event, be intolerant of high doses of the study drug, or require permanent withdrawal of treatment (p < 0.001 for all). However, these risks were primarily related to the severity of the underlying illness and not to treatment with carvedilol. The current study provides little support for concerns about using beta-blockers (particularly those with vasodilatory actions) in patients with severe CHF who have a low SBP. Pretreatment blood pressure can identify patients who have the greatest need for risk reduction with carvedilol.

  12. Usability Evaluation of a Web-Based Symptom Monitoring Application for Heart Failure.

    PubMed

    Wakefield, Bonnie; Pham, Kassie; Scherubel, Melody

    2015-07-01

    Symptom recognition and reporting by patients with heart failure are critical to avoid hospitalization. This project evaluated a patient symptom tracking application. Fourteen end users (nine patients, five clinicians) from a Midwestern Veterans Affairs Medical Center evaluated the website using a think aloud protocol. A structured observation protocol was used to assess success or failure for each task. Measures included task time, success, and satisfaction. Patients had a mean age of 70 years; clinicians averaged 42 years in age. Patients took 9.3 min and clinicians took less than 3 min per scenario. Most patients needed some assistance, but few patients were completely unable to complete some tasks. Clinicians demonstrated few problems navigating the site. Patient System Usability Scale item scores ranged from 2.0 to 3.6; clinician item scores ranged from 1.8 to 4.0. Further work is needed to determine whether using the web-based tool improves symptom recognition and reporting. © The Author(s) 2015.

  13. Failure of Non-Circular Composite Cylinders

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.

    2004-01-01

    In this study, a progressive failure analysis is used to investigate leakage in internally pressurized non-circular composite cylinders. This type of approach accounts for the localized loss of stiffness when material failure occurs at some location in a structure by degrading the local material elastic properties by a certain factor. The manner in which this degradation of material properties takes place depends on the failure modes, which are determined by the application of a failure criterion. The finite-element code STAGS, which has the capability to perform progressive failure analysis using different degradation schemes and failure criteria, is utilized to analyze laboratory scale, graphite-epoxy, elliptical cylinders with quasi-isotropic, circumferentially-stiff, and axially-stiff material orthotropies. The results are divided into two parts. The first part shows that leakage, which is assumed to develop if there is material failure in every layer at some axial and circumferential location within the cylinder, does not occur without failure of fibers. Moreover before fibers begin to fail, only matrix tensile failures, or matrix cracking, takes place, and at least one layer in all three cylinders studied remain uncracked, preventing the formation of a leakage path. That determination is corroborated by the use of different degradation schemes and various failure criteria. Among the degradation schemes investigated are the degradation of different engineering properties, the use of various degradation factors, the recursive or non-recursive degradation of the engineering properties, and the degradation of material properties using different computational approaches. The failure criteria used in the analysis include the noninteractive maximum stress criterion and the interactive Hashin and Tsai-Wu criteria. The second part of the results shows that leakage occurs due to a combination of matrix tensile and compressive, fiber tensile and compressive, and inplane

  14. Evaluation of Pad 18 Spent Mercury Gold Trap Stainless Steel Container Failure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Skidmore, E.

    Failure of the Pad 18 spent mercury gold trap stainless steel waste container is principally attributed to corrosion induced by degradation of plasticized polyvinyl chloride (pPVC) waste packaging material. Dehydrochlorination of pPVC polymer by thermal and/or radiolytic degradation is well-known to evolve HCl gas, which is highly corrosive to stainless steel and other metals in the presence of moisture. Degradation of the pPVC packaging material was likely caused by radiolysis in the presence of tritium gas within the waste container, though other degradation mechanisms (aging, thermo-oxidation, plasticizer migration) over 30 years storage may have contributed. Corrosion was also likely enhancedmore » by the crevice in the container weld design, and may have been enhanced by the presence of tritiated water. Similar non-failed spent mercury gold trap waste containers did not show radiographic evidence of plastic packaging or trapped free liquid within the container. Therefore, those containers are not expected to exhibit similar failures. Halogenated polymers such as pPVC subject to degradation can evolve halide gases such as HCl, which is corrosive in the presence of moisture and can generate pressure in sealed systems.« less

  15. Structural design, analysis, and code evaluation of an odd-shaped pressure vessel

    NASA Astrophysics Data System (ADS)

    Rezvani, M. A.; Ziada, H. H.

    1992-12-01

    An effort to design, analyze, and evaluate a rectangular pressure vessel is described. Normally pressure vessels are designed in circular or spherical shapes to prevent stress concentrations. In this case, because of operational limitations, the choice of vessels was limited to a rectangular pressure box with a removable cover plate. The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code is used as a guideline for pressure containments whose width or depth exceeds 15.24 cm (6.0 in.) and where pressures will exceed 103.4 KPa (15.0 lbf/in(sup 2)). This evaluation used Section 8 of this Code, hereafter referred to as the Code. The dimensions and working pressure of the subject vessel fall within the pressure vessel category of the Code. The Code design guidelines and rules do not directly apply to this vessel. Therefore, finite-element methodology was used to analyze the pressure vessel, and the Code then was used in qualifying the vessel to be stamped to the Code. Section 8, Division 1 of the Code was used for evaluation. This action was justified by selecting a material for which fatigue damage would not be a concern. The stress analysis results were then checked against the Code, and the thicknesses adjusted to satisfy Code requirements. Although not directly applicable, the Code design formulas for rectangular vessels were also considered and presented.

  16. Mechanistic investigation of drug release from asymmetric membrane tablets: effect of media gradients (osmotic pressure and concentration), and potential coating failures on in vitro release.

    PubMed

    Am Ende, Mary Tanya; Miller, Lee A

    2007-02-01

    An asymmetric membrane (AM) tablet was developed for a soluble model compound to study the in vitro drug release mechanisms in challenge conditions, including osmotic gradients, concentration gradients, and under potential coating failure modes. Porous, semipermable membrane integrity may be compromised by a high fat meal or by the presence of a defect in the coating that could cause a safety concern about dose-dumping. The osmotic and diffusional release mechanisms of the AM tablet were independently shut down such that their individual contribution to the overall drug release was measured. Shut off of osmotic and diffusional release was accomplished by performing dissolution studies into receptor solutions with osmotic pressure above the internal core osmotic pressure and into receptor solutions saturated with drug, respectively. The effect of coating failure modes on in vitro drug release from the AM tablet was assessed through a simulated high-fat meal and by intentionally compromising the coating integrity. The predominant drug release mechanism for the AM tablet was osmotic and accounted for approximately 90-95% of the total release. Osmotic release was shutoff when the receptor media osmotic pressure exceeded 76 atm. Diffusional release of the soluble drug amounted to 5-10% of the total release mechanism. The observed negative in vitro food effect was attributed to the increased osmotic pressure from the high fat meal when compared to the predicted release rates in sucrose media with the same osmotic pressure. This suppression in drug release rate due to a high fat meal is not anticipated to affect in vivo performance of the dosage form, as the rise in pressure is short-lived. Drug release from the AM system studied was determined to be robust to varying and extreme challenge conditions. The conditions investigated included varying pH, agitation rate, media osmotic pressure, media saturated with drug to eliminate the concentration gradient, simulated high

  17. Dialysate temperature adjustment as an effective treatment for baroreflex failure syndrome in hemodialysis patient.

    PubMed

    Tanabe, Natsumi; Takane, Koki; Yokoyama, Keitaro; Tanno, Yudo; Yamamoto, Izumi; Ohkido, Ichiro; Yokoo, Takashi

    2014-09-17

    Baroreflex failure syndrome is a rare disorder which causes labile blood pressure, headache, flushing, diaphoresis and emotional lability. It is caused by history of trauma or radiotherapy in the cervical legion, bilateral carotid-body tumor or resection of glossopharyngeal nerve. We experienced a case of hemodialysis patient who had difficulty in controlling blood pressure during dialysis because of his baroreflex failure syndrome and successfully controlled his blood pressure by adjusting dialysate temperature. We report a case of a 68-year-old CKD5 patient who had difficulty in hemodialysis treatment because of severe fluctuations in blood pressure with hypertensive attacks and hypotensive episodes which caused him a severe discomfort. His dialysis treatment was started in 2010 and since that time baroreflex failure syndrome has been suspected because of his clinical manifestations and history of radiotherapy in the cervical region for his lingual cancer in 1994. Baroreflex failure syndrome is diagnosed by symptoms and cold stressor test. We performed a cold stressor test on an experimental baroreflex failure syndrome mouse and induced a significant elevation of blood pressure. From this experimental finding of model mouse, we changed the patients dialysate temperature between 34-38° according to his change in blood pressure though 80-240 mmHg. From this attempt, his blood pressure was successfully controlled between 100-180 mmHg and he was able to continue hemodialysis without any discomfort. In our case, environmental stimulation such as temperature change modified the patients fluctuating blood pressure. Change of dialysate temperature could be an option for controlling the unstable blood pressure due to baroreflex failure syndrome.

  18. Adherence to Positive Airway Pressure Therapy in Hospitalized Patients with Decompensated Heart Failure and Sleep-Disordered Breathing

    PubMed Central

    Sharma, Sunil; Chakraborty, Anasua; Chowdhury, Anindita; Mukhtar, Umer; Willes, Leslee; Quan, Stuart F.

    2016-01-01

    Study Objectives: Sleep-disordered breathing (SDB) has been implicated as a risk factor for the development of several adverse cardiovascular outcomes, but can be mitigated with positive airway pressure therapy (PAP). The nonadherence of patients with SDB on PAP in the outpatient setting ranges from 29% to 84%. However, adherence of PAP in patients with congestive heart failure (CHF) admitted for decompensated CHF and in whom SDB has been diagnosed in the hospital setting is not known. We hypothesized that despite a diagnosis in the hospital, the compliance of these patients with PAP therapy would not be different from the well-established adherence in patients with a diagnosis and treatment in the outpatient setting. Methods: The study was a retrospective analysis of patients admitted to an academic tertiary care hospital between March 2013 and February 2014. Patients presenting with decompensated CHF were screened and high-risk patients were started on PAP empirically and advised to undergo a postdischarge polysomnogram. Compliance of the patients with PAP was tracked for over 12 mo. Data from a similar outpatient group who underwent polysomnography during the study period were also reviewed. Results: Ninety-one patients underwent polysomnograhy postdischarge. Of the 91 patients, 81 patients agreed to PAP therapy. One patient was excluded as data were missing. The adherence at 3, 6, and 12 mo was 52%, 37%, and 27%, which was not significantly different than an outpatient control group. There was a trend for those with CHF plus SDB and compliant with PAP to have a higher probability of survival compared to those who were noncompliant (p = 0.07). Conclusions: Adherence of patients to PAP therapy in whom a SDB diagnosis is made during acute hospitalization for heart failure is comparable to patients in the ambulatory setting. Adherence in first 3 mo is a predictive marker for improved survival trend. Citation: Sharma S, Chakraborty A, Chowdhury A, Mukhtar U, Willes

  19. Progressive Fracture of Fiber Composite Thin Shell Structures Under Internal Pressure and Axial Loads

    NASA Technical Reports Server (NTRS)

    Gotsis, Pascal K.; Chamis, Christos C.; Minnetyan, Levon

    1996-01-01

    Graphite/epoxy composite thin shell structures were simulated to investigate damage and fracture progression due to internal pressure and axial loading. Defective and defect-free structures (thin cylinders) were examined. The three different laminates examined had fiber orientations of (90/0/+/-0)(sub s), where 0 is 45, 60, and 75 deg. CODSTRAN, an integrated computer code that scales up constituent level properties to the structural level and accounts for all possible failure modes, was used to simulate composite degradation under loading. Damage initiation, growth, accumulation, and propagation to fracture were included in the simulation. Burst pressures for defective and defect-free shells were compared to evaluate damage tolerance. The results showed that damage initiation began with matrix failure whereas damage and/or fracture progression occurred as a result of additional matrix failure and fiber fracture. In both thin cylinder cases examined (defective and defect-free), the optimum layup configuration was (90/0/+/-60)(sub s) because it had the best damage tolerance with respect to the burst pressure.

  20. Evaluating the operational risks of biomedical waste using failure mode and effects analysis.

    PubMed

    Chen, Ying-Chu; Tsai, Pei-Yi

    2017-06-01

    The potential problems and risks of biomedical waste generation have become increasingly apparent in recent years. This study applied a failure mode and effects analysis to evaluate the operational problems and risks of biomedical waste. The microbiological contamination of biomedical waste seldom receives the attention of researchers. In this study, the biomedical waste lifecycle was divided into seven processes: Production, classification, packaging, sterilisation, weighing, storage, and transportation. Twenty main failure modes were identified in these phases and risks were assessed based on their risk priority numbers. The failure modes in the production phase accounted for the highest proportion of the risk priority number score (27.7%). In the packaging phase, the failure mode 'sharp articles not placed in solid containers' had the highest risk priority number score, mainly owing to its high severity rating. The sterilisation process is the main difference in the treatment of infectious and non-infectious biomedical waste. The failure modes in the sterilisation phase were mainly owing to human factors (mostly related to operators). This study increases the understanding of the potential problems and risks associated with biomedical waste, thereby increasing awareness of how to improve the management of biomedical waste to better protect workers, the public, and the environment.

  1. Lox/Gox related failures during Space Shuttle Main Engine development

    NASA Technical Reports Server (NTRS)

    Cataldo, C. E.

    1981-01-01

    Specific rocket engine hardware and test facility system failures are described which were caused by high pressure liquid and/or gaseous oxygen reactions. The failures were encountered during the development and testing of the space shuttle main engine. Failure mechanisms are discussed as well as corrective actions taken to prevent or reduce the potential of future failures.

  2. [Evaluation of pressure ulcers area using the softwares Motic and AutoCAD®].

    PubMed

    Reis, Camila Letícia Dias dos; Cavalcante, Janaína Mortosa; Rocha Júnior, Edvar Ferreira da; Neves, Rinaldo Souza; Santana, Levy Aniceto; Guadagnin, Renato da Veiga; Brasil, Lourdes Mattos

    2012-01-01

    Pressure ulcer is a lesion that affects skin layers in some regions of the body and its healing can be followed up using image processing. The analysis of pressure ulcer area is relevant to evaluate its evolution and response to therapeutic procedures. Such areas can be evaluated through contour marking with the softwares Motic and AutoCAD®. In this study 35 volunteers computed areas from two grade III pressure ulcers using these instruments. It was possible to conclude that results are clinically equivalent and so can be considered to follow up healing evolution from pressure ulcers.

  3. Galectin-3: A Link between Myocardial and Arterial Stiffening in Patients with Acute Decompensated Heart Failure?

    PubMed

    Lala, Radu Ioan; Darabantiu, Dan; Pilat, Luminita; Puschita, Maria

    2016-02-01

    Heart failure is accompanied by abnormalities in ventricular-vascular interaction due to increased myocardial and arterial stiffness. Galectin-3 is a recently discovered biomarker that plays an important role in myocardial and vascular fibrosis and heart failure progression. The aim of this study was to determine whether galectin-3 is correlated with arterial stiffening markers and impaired ventricular-arterial coupling in decompensated heart failure patients. A total of 79 inpatients with acute decompensated heart failure were evaluated. Serum galectin-3 was determined at baseline, and during admission, transthoracic echocardiography and measurements of vascular indices by Doppler ultrasonography were performed. Elevated pulse wave velocity and low arterial carotid distensibility are associated with heart failure in patients with preserved ejection fraction (p = 0.04, p = 0.009). Pulse wave velocity, carotid distensibility and Young's modulus did not correlate with serum galectin-3 levels. Conversely, raised galectin-3 levels correlated with an increased ventricular-arterial coupling ratio (Ea/Elv) p = 0.047, OR = 1.9, 95% CI (1.0‑3.6). Increased galectin-3 levels were associated with lower rates of left ventricular pressure rise in early systole (dp/dt) (p=0.018) and raised pulmonary artery pressure (p = 0.046). High galectin-3 levels (p = 0.038, HR = 3.07) and arterial pulmonary pressure (p = 0.007, HR = 1.06) were found to be independent risk factors for all-cause mortality and readmissions. This study showed no significant correlation between serum galectin-3 levels and arterial stiffening markers. Instead, high galectin-3 levels predicted impaired ventricular-arterial coupling. Galectin-3 may be predictive of raised pulmonary artery pressures. Elevated galectin-3 levels correlate with severe systolic dysfunction and together with pulmonary hypertension are independent markers of outcome.

  4. Blood Pressure Control

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Engineering Development Laboratory developed a system for the cardiovascular study of weightless astronauts. This was designed to aid people with congestive heart failure and diabetes. While in space, astronauts' blood pressure rises, heart rate becomes unstable, and there are sometimes postflight lightheadedness or blackouts. The Baro-Cuff studies the resetting of blood pressure. When a silicone rubber chamber is strapped to the neck, the Baro-Cuff stimulates the carotid arteries by electronically controlled pressure application. Blood pressure controls in patients may be studied.

  5. Evaluating the risk of water distribution system failure: A shared frailty model

    NASA Astrophysics Data System (ADS)

    Clark, Robert M.; Thurnau, Robert C.

    2011-12-01

    Condition assessment (CA) Modeling is drawing increasing interest as a technique that can assist in managing drinking water infrastructure. This paper develops a model based on the application of a Cox proportional hazard (PH)/shared frailty model and applies it to evaluating the risk of failure in drinking water networks using data from the Laramie Water Utility (located in Laramie, Wyoming, USA). Using the risk model a cost/ benefit analysis incorporating the inspection value method (IVM), is used to assist in making improved repair, replacement and rehabilitation decisions for selected drinking water distribution system pipes. A separate model is developed to predict failures in prestressed concrete cylinder pipe (PCCP). Various currently available inspection technologies are presented and discussed.

  6. Determination of a tissue-level failure evaluation standard for rat femoral cortical bone utilizing a hybrid computational-experimental method.

    PubMed

    Fan, Ruoxun; Liu, Jie; Jia, Zhengbin; Deng, Ying; Liu, Jun

    2018-01-01

    Macro-level failure in bone structure could be diagnosed by pain or physical examination. However, diagnosing tissue-level failure in a timely manner is challenging due to the difficulty in observing the interior mechanical environment of bone tissue. Because most fractures begin with tissue-level failure in bone tissue caused by continually applied loading, people attempt to monitor the tissue-level failure of bone and provide corresponding measures to prevent fracture. Many tissue-level mechanical parameters of bone could be predicted or measured; however, the value of the parameter may vary among different specimens belonging to a kind of bone structure even at the same age and anatomical site. These variations cause difficulty in representing tissue-level bone failure. Therefore, determining an appropriate tissue-level failure evaluation standard is necessary to represent tissue-level bone failure. In this study, the yield and failure processes of rat femoral cortical bones were primarily simulated through a hybrid computational-experimental method. Subsequently, the tissue-level strains and the ratio between tissue-level failure and yield strains in cortical bones were predicted. The results indicated that certain differences existed in tissue-level strains; however, slight variations in the ratio were observed among different cortical bones. Therefore, the ratio between tissue-level failure and yield strains for a kind of bone structure could be determined. This ratio may then be regarded as an appropriate tissue-level failure evaluation standard to represent the mechanical status of bone tissue.

  7. Warning Signs of Heart Failure

    MedlinePlus

    ... the two terms are used interchangeably. View an animation of heart failure . If you have been diagnosed ... resources here Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  8. Porting Initiation and Failure into Linked CHEETAH

    NASA Astrophysics Data System (ADS)

    Souers, Clark; Vitello, Peter

    2007-06-01

    Linked CHEETAH is a thermo-chemical code coupled to a 2-D hydrocode. Initially, a quadratic-pressure dependent kinetic rate was used, which worked well in modeling prompt detonation of explosives of large size, but does not work on other aspects of explosive behavior. The variable-pressure Tarantula reactive flow rate model was developed with JWL++ in order to also describe failure and initiation, and we have moved this model into Linked CHEETAH. The model works by turning on only above a pressure threshold, where a slow turn-on creates initiation. At a higher pressure, the rate suddenly leaps to a large value over a small pressure range. A slowly failing cylinder will see a rapidly declining rate, which pushes it quickly into failure. At a high pressure, the detonation rate is constant. A sequential validation procedure is used, which includes metal-confined cylinders, rate-sticks, corner-turning, initiation and threshold, gap tests and air gaps. The size (diameter) effect is central to the calibration. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

  9. Rescue therapy by switching to total face mask after failure of face mask-delivered noninvasive ventilation in do-not-intubate patients in acute respiratory failure.

    PubMed

    Lemyze, Malcolm; Mallat, Jihad; Nigeon, Olivier; Barrailler, Stéphanie; Pepy, Florent; Gasan, Gaëlle; Vangrunderbeeck, Nicolas; Grosset, Philippe; Tronchon, Laurent; Thevenin, Didier

    2013-02-01

    To evaluate the impact of switching to total face mask in cases where face mask-delivered noninvasive mechanical ventilation has already failed in do-not-intubate patients in acute respiratory failure. Prospective observational study in an ICU and a respiratory stepdown unit over a 12-month study period. Switching to total face mask, which covers the entire face, when noninvasive mechanical ventilation using facial mask (oronasal mask) failed to reverse acute respiratory failure. Seventy-four patients with a do-not-intubate order and treated by noninvasive mechanical ventilation for acute respiratory failure. Failure of face mask-delivered noninvasive mechanical ventilation was associated with a three-fold increase in in-hospital mortality (36% vs. 10.5%; p = 0.009). Nevertheless, 23 out of 36 patients (64%) in whom face mask-delivered noninvasive mechanical ventilation failed to reverse acute respiratory failure and, therefore, switched to total face mask survived hospital discharge. Reasons for switching from facial mask to total face mask included refractory hypercapnic acute respiratory failure (n = 24, 66.7%), painful skin breakdown or facial mask intolerance (n = 11, 30%), and refractory hypoxemia (n = 1, 2.7%). In the 24 patients switched from facial mask to total face mask because of refractory hypercapnia, encephalopathy score (3 [3-4] vs. 2 [2-3]; p < 0.0001), PaCO2 (87 ± 25 mm Hg vs. 70 ± 17 mm Hg; p < 0.0001), and pH (7.24 ± 0.1 vs. 7.32 ± 0.09; p < 0.0001) significantly improved after 2 hrs of total face mask-delivered noninvasive ventilation. Patients switched early to total face mask (in the first 12 hrs) developed less pressure sores (n = 5, 24% vs. n = 13, 87%; p = 0.0002), despite greater length of noninvasive mechanical ventilation within the first 48 hrs (44 hrs vs. 34 hrs; p = 0.05) and less protective dressings (n = 2, 9.5% vs. n = 8, 53.3%; p = 0.007). The optimal cutoff value for face mask-delivered noninvasive mechanical ventilation

  10. Comparison of water and air charged transducer catheter pressures in the evaluation of cystometrogram and voiding pressure studies.

    PubMed

    McKinney, Timothy B; Babin, Elizabeth A; Ciolfi, Veronica; McKinney, Cynthia R; Shah, Nima

    2018-04-01

    Air-charged (AC) and water-perfused (WP) catheters have been evaluated for differences in measuring pressures for voiding dysfunction. Typically, a two-catheter system was used. We believe that simultaneous pressure measurements with AC and WP in a single catheter will provide analogous pressures for coughs, Valsalvas, and maximum pressures in voiding pressure studies (VPS). This IRB approved prospective study included 50 women over age 21. AC dual TDOC catheters were utilized. The water-filling channel served as the bladder filler and the water pressure readings. Patients were evaluated with empty bladders and at volumes of 50-100 mL, 200 mL, and maximum capacity with cough and Valsalva maneuvers. Comparative analysis was performed on maximum stress peak pressures. At maximum bladder capacity, VPS was done and maximum voiding pressure was recorded. Comparing coughs and Valsalva maneuvers pressures, there was significant increase in variability between AC and WP measurements with less than 50 mL volume (P < 0.001). Significant correlations were observed between AC and WP measurements for coughs and Valsalvas with bladder volume over 50 mL. Visual impression showed virtually identical tracings. Cough measurements had an average difference of 0.25 cmH 2 O (±8.81) and Valsalva measurements had an average difference of 3.15 cmH 2 O (±4.72). Thirty-eight women had usable maximum voiding pressure measurements and had a strong correlation. Cystometrogram and maximum voiding pressure measurements done with either water or air charged catheters will yield similarly accurate results and are comparable. Results suggest more variability at low bladder volumes <50 mL. © 2018 Wiley Periodicals, Inc.

  11. Diagnosis and management of baroreflex failure

    NASA Technical Reports Server (NTRS)

    Robertson, D.

    1995-01-01

    Baroreflex failure has a range of presentations, varying from the acute onset of a hypertensive crisis to a chronically volatile blood pressure and heart rate with hypertensive surges in response to stress, punctuated by periods of normal or even low blood pressure during rest. Differentiating this syndrome from other causes of labile hypertension is essential in devising effective treatment.

  12. Acoustic emission testing of 12-nickel maraging steel pressure vessels

    NASA Technical Reports Server (NTRS)

    Dunegan, H. L.

    1973-01-01

    Acoustic emission data were obtained from three point bend fracture toughness specimens of 12-nickel maraging steel, and two pressure vessels of the same material. One of the pressure vessels contained a prefabricated flaw which was extended and sharpened by fatigue cycling. It is shown that the flawed vessel had similar characteristics to the fracture specimens, thereby allowing estimates to be made of its nearness to failure during a proof test. Both the flawed and unflawed pressure vessel survived the proof pressure and 5 cycles to the working pressure, but it was apparent from the acoustic emission response during the proof cycle and the 5 cycles to the working pressure that the flawed vessel was very near failure. The flawed vessel did not survive a second cycle to the proof pressure before failure due to flaw extension through the wall (causing a leak).

  13. Data and Statistics: Heart Failure

    MedlinePlus

    ... commit" type="submit" value="Submit" /> Related CDC Web Sites Heart Disease Stroke High Blood Pressure Salt ... to Prevent and Control Chronic Diseases Million Hearts® Web Sites with More Information About Heart Failure For ...

  14. Evaluation of rotating, incompressibly lubricated, pressurized thrust bearings

    NASA Technical Reports Server (NTRS)

    Fleming, D. P.

    1971-01-01

    Program evaluates a series hybrid, fluid film ball bearing consisting of an orifice compensated pressurized thrust bearing in conjunction with a self-acting journal bearing. Oil viscosities corresponding to experimentally measured ball bearing outer-race temperatures were used.

  15. Evaluation of films for packaging applications in high pressure processing

    NASA Astrophysics Data System (ADS)

    Largeteau, A.; Angulo, I.; Coulet, J. P.; Demazeau, G.

    2010-03-01

    Food treatments implying high pressures used pre-packaging systems; consequently it appeared necessary to validate different packaging films able to be used in such processes. Two different packaging films from AMCOR FLEXIBLES have been evaluated: VIROFLEXAL: BOLSA 80 MICRAS, coextrusion PA/PE (20/60μm) RILTHENE: SEMI 20/60 MICRAS, laminate PA/PE (20/60μm) Three different physico-chemical characterizations have been developed for the evaluation of films behaviour after High Hydrostatic Pressure (HHP): (i) Mechanical properties (tensile strength and sealing strength), (ii) Oxygen permeability, (iii) Migration, through the contact with four food simulating liquids FSLs (water, acetic acid 3%, ethyl alcohol 10%, iso-octane). Two different pressures values (P = 400MPa and 500MPa) have been tested, with a duration of 15 min, at ambient temperature (+20°C) and only one pressure (P = 200MPa) for the experiments at low temperature (T = -20°C) with the same duration (15min). The selection of such values can be justified taking into account that experimental conditions as a temperature close to +20°C and a pressure between 400 and 500MPa are appropriated to inactivate bacteria and different others micro-organisms. Due to the efficiency of the association of hydrostatic pressure processing and low temperature (HHP/LT) [1, 2], the same films have been tested under high pressure processing (200MPa) but at negative temperature (-20°C).

  16. TSS-1R Failure Mode Evaluation

    NASA Technical Reports Server (NTRS)

    Vaughn, Jason A.; McCollum, Matthew B.; Kamenetzky, Rachel R.

    1997-01-01

    Soon after the break of the tether during the Tethered Satellite System (TSS-1R) mission in February, 1996, a Tiger Team was assembled at the George C. Marshall Space Flight Center to determine the tether failure mode. One possible failure scenario was the Kevlar' strength member of the tether failed because of degradation due to electrical discharge or electrical arcing. During the next several weeks, extensive electrical discharge testing in low vacuum and plasma environments was conducted in an attempt to reproduce the electrical activity recorded by on-board science instruments during the mission. The results of these tests are presented in this paper.

  17. Mothers' Attributions in Reminiscing Conversations about Children's Successes and Failures: Connections with Children's Self-Evaluations

    ERIC Educational Resources Information Center

    Goodvin, Rebecca; Rolfson, Jacqueline

    2014-01-01

    Effects of feedback on children's self-evaluations are well established, yet little is known about how parents talk with children about everyday successes and failures, despite the importance of parent-child reminiscing in children's psychological understanding. We examine mothers' attributions and performance evaluations in conversations about…

  18. Research study of pressure instrumentation

    NASA Technical Reports Server (NTRS)

    Hoogenboom, L.; Hull-Allen, G.

    1984-01-01

    To obtain a more vibration resistant pressure sensor for use on the Space Shuttle Main Engine, a proximity probe based, diaphragm type pressure sensor breadboard was developed. A fiber optic proximity probe was selected as the sensor. In combination with existing electronics, a thermal stability evaluation of the entire probe system was made. Based upon the results, a breadboard design of the pressure sensor and electronics was made and fabricated. A brief series of functional experiments was made with the breadboard to calibrate, thermally compensate, and linearize its response. In these experiments, the performance obtained in the temperature range of -320 F (liquid N2) to +200 F was comparable to that of the strain gage based sensor presently in use on the engine. In tests at NASA-Marshall Space Flight Center (MSFC), after some time at or near liquid nitrogen temperatures, the sensor output varied over the entire output range. These large spurious signals were attributed to condensation of air in the sensing gap. In the next phase of development of this sensor, an evaluation of fabrication techniques toward greater thermal and mechanical stability of the fiber probe assembly must be made. In addition to this, a positive optics to metal seal must be developed to withstand the pressure that would result from a diaphragm failure.

  19. An ex vivo porcine skin model to evaluate pressure-reducing devices of different mechanical properties used for pressure ulcer prevention.

    PubMed

    Yeung, Ching-Yan C; Holmes, David F; Thomason, Helen A; Stephenson, Christian; Derby, Brian; Hardman, Matthew J

    2016-11-01

    Pressure ulcers are complex wounds caused by pressure- and shear-induced trauma to skin and underlying tissues. Pressure-reducing devices, such as dressings, have been shown to successfully reduce pressure ulcer incidence, when used in adjunct to pressure ulcer preventative care. While pressure-reducing devices are available in a range of materials, with differing mechanical properties, understanding of how a material's mechanical properties will influence clinical efficacy remains limited. The aim of this study was to establish a standardized ex vivo model to allow comparison of the cell protection potential of two gel-like pressure-reducing devices with differing mechanical properties (elastic moduli of 77 vs. 35 kPa). The devices also displayed differing energy dissipation under compressive loading, and resisted strain differently under constant load in compressive creep tests. To evaluate biological efficacy we employed a new ex vivo porcine skin model, with a confirmed elastic moduli closely matching that of human skin (113 vs. 119 kPa, respectively). Static loads up to 20 kPa were applied to porcine skin ex vivo with subsequent evaluation of pressure-induced cell death and cytokine release. Pressure application alone increased the percentage of epidermal apoptotic cells from less than 2% to over 40%, and increased cellular secretion of the pro-inflammatory cytokine TNF-alpha. Co-application of a pressure-reducing device significantly reduced both cellular apoptosis and cytokine production, protecting against cellular damage. These data reveal new insight into the relationship between mechanical properties of pressure-reducing devices and their biological effects. After appropriate validation of these results in clinical pressure ulcer prevention with all tissue layers present between the bony prominence and external surface, this ex vivo porcine skin model could be widely employed to optimize design and evaluation of devices aimed at reducing pressure

  20. Non-invasive high-frequency ventilation versus bi-phasic continuous positive airway pressure (BP-CPAP) following CPAP failure in infants <1250 g: a pilot randomized controlled trial.

    PubMed

    Mukerji, A; Sarmiento, K; Lee, B; Hassall, K; Shah, V

    2017-01-01

    Non-invasive high-frequency ventilation (NIHFV), a relatively new modality, is gaining popularity despite limited data. We sought to evaluate the effectiveness of NIHFV versus bi-phasic continuous positive airway pressure (BP-CPAP) in preterm infants failing CPAP. Infants with BW<1250 g on CPAP were randomly assigned to NIHFV or BP-CPAP if they met pre-determined criteria for CPAP failure. Infants were eligible for randomization after 72 h age and until 2000 g. Guidelines for adjustment of settings and criteria for failure of assigned mode were implemented. The primary aim was to assess feasibility of a larger trial. In addition, failure of assigned non-invasive respiratory support (NRS) mode, invasive mechanical ventilation (MV) 72 h and 7 days post-randomization, and bronchopulmonary dysplasia (BPD) were assessed. Thirty-nine infants were randomized to NIHFV (N=16) or BP-CPAP (N=23). There were no significant differences in mean (s.d.) postmenstrual age (28.6 (1.5) versus 29.0 (2.3) weeks, P=0.47), mean (s.d.) weight at randomization (965.0 (227.0) versus 958.1 (310.4) g, P=0.94) or other baseline demographics between the groups. Failure of assigned NRS mode was lower with NIHFV (37.5 versus 65.2%, P=0.09), although not statistically significant. There were no differences in rates of invasive MV 72 h and 7 days post-randomization or BPD. NIHFV was not superior to BP-CPAP in this pilot study. Effectiveness of NIHFV needs to be proven in larger multi-center, appropriately powered trials before widespread implementation.

  1. Exercise Blood Pressure Guidelines: Time to Re-evaluate What is Normal and Exaggerated?

    PubMed

    Currie, Katharine D; Floras, John S; La Gerche, Andre; Goodman, Jack M

    2018-03-24

    Blood pressure responses to graded exercise testing can provide important diagnostic and prognostic information. While published guidelines outline what constitutes a "normal" and "abnormal" (i.e., exaggerated) blood pressure response to exercise testing, the widespread use of exaggerated blood pressure responses as a clinical tool is limited due to sparse and inconsistent data. A review of the original sources from these guidelines reveals an overall lack of empirical evidence to support both the normal blood pressure responses and their upper limits. In this current opinion, we critically evaluate the current exercise blood pressure guidelines including (1) the normal blood pressure responses to graded exercise testing; (2) the upper limits of this normal response; (3) the blood pressure criteria for test termination; and (4) the thresholds for exaggerated blood pressure responses. We provide evidence that exercise blood pressure responses vary according to subject characteristics, and subsequently a re-evaluation of what constitutes normal and abnormal responses is necessary to strengthen the clinical utility of this assessment.

  2. Scare Tactics: Evaluating Problem Decompositions Using Failure Scenarios

    NASA Technical Reports Server (NTRS)

    Helm, B. Robert; Fickas, Stephen

    1992-01-01

    Our interest is in the design of multi-agent problem-solving systems, which we refer to as composite systems. We have proposed an approach to composite system design by decomposition of problem statements. An automated assistant called Critter provides a library of reusable design transformations which allow a human analyst to search the space of decompositions for a problem. In this paper we describe a method for evaluating and critiquing problem decompositions generated by this search process. The method uses knowledge stored in the form of failure decompositions attached to design transformations. We suggest the benefits of our critiquing method by showing how it could re-derive steps of a published development example. We then identify several open issues for the method.

  3. [Acute heart failure: acute cardiogenic pulmonary edema and cardiogenic shock].

    PubMed

    Sánchez Marteles, Marta; Urrutia, Agustín

    2014-03-01

    Acute cardiogenic pulmonary edema and cardiogenic shock are two of the main forms of presentation of acute heart failure. Both entities are serious, with high mortality, and require early diagnosis and prompt and aggressive management. Acute pulmonary edema is due to the passage of fluid through the alveolarcapillary membrane and is usually the result of an acute cardiac episode. Correct evaluation and clinical identification of the process is essential in the management of acute pulmonary edema. The initial aim of treatment is to ensure hemodynamic stability and to correct hypoxemia. Other measures that can be used are vasodilators such as nitroglycerin, loop diuretics and, in specific instances, opioids. Cardiogenic shock is characterized by sustained hypoperfusion, pulmonary wedge pressure > 18 mmHg and a cardiac index < 2.2l/min/m(2). The process typically presents with hypotension (systolic blood pressure < 90 mmHg or a decrease in mean arterial pressure > 30 mmHg) and absent or reduced diuresis (< 0.5 ml/kg/h). The most common cause is left ventricular failure due to acute myocardial infarction. Treatment consists of general measures to reverse acidosis and hypoxemia, as well as the use of vasopressors and inotropic drugs. Early coronary revascularization has been demonstrated to improve survival in shock associated with ischaemic heart disease. Copyright © 2014 Elsevier España, S.L. All rights reserved.

  4. A finite element evaluation of the moment arm hypothesis for altered vertebral shear failure force.

    PubMed

    Howarth, Samuel J; Karakolis, Thomas; Callaghan, Jack P

    2015-01-01

    The mechanism of vertebral shear failure is likely a bending moment generated about the pars interarticularis by facet contact, and the moment arm length (MAL) between the centroid of facet contact and the location of pars interarticularis failure has been hypothesised to be an influential modulator of shear failure force. To quantitatively evaluate this hypothesis, anterior shear of C3 over C4 was simulated in a finite element model of the porcine C3-C4 vertebral joint with each combination of five compressive force magnitudes (0-60% of estimated compressive failure force) and three postures (flexed, neutral and extended). Bilateral locations of peak stress within C3's pars interarticularis were identified along with the centroids of contact force on the inferior facets. These measurements were used to calculate the MAL of facet contact force. Changes in MAL were also related to shear failure forces measured from similar in vitro tests. Flexed and extended vertebral postures respectively increased and decreased the MAL by 6.6% and 4.8%. The MAL decreased by only 2.6% from the smallest to the largest compressive force. Furthermore, altered MAL explained 70% of the variance in measured shear failure force from comparable in vitro testing with larger MALs being associated with lower shear failure forces. Our results confirmed that the MAL is indeed a significant modulator of vertebral shear failure force. Considering spine flexion is necessary when assessing low-back shear injury potential because of the association between altered facet articulation and lower vertebral shear failure tolerance.

  5. Laboratory evaluation of the pressure water level data logger manufactured by Infinities USA, Inc.: results of pressure and temperature tests

    USGS Publications Warehouse

    Carnley, Mark V.

    2015-01-01

    The Pressure Water Level Data Logger manufactured by Infinities USA, Inc., was evaluated by the U.S. Geological Survey (USGS) Hydrologic Instrumentation Facility for conformance with the manufacturer’s stated accuracy specifications for measuring pressure throughout the device’s operating temperature range and with the USGS accuracy requirements for water-level measurements. The Pressure Water Level Data Logger (Infinities Logger) is a submersible, sealed, water-level sensing device with an operating pressure range of 0 to 11.5 feet of water over a temperature range of −18 to 49 degrees Celsius. For the pressure range tested, the manufacturer’s accuracy specification of 0.1 percent of full scale pressure equals an accuracy of ±0.138 inch of water. Three Infinities Loggers were evaluated, and the testing procedures followed and results obtained are described in this report. On the basis of the test results, the device is poorly compensated for temperature. For the three Infinities Loggers, the mean pressure differences varied from –4.04 to 5.32 inches of water and were not within the manufacturer’s accuracy specification for pressure measurements made within the temperature-compensated range. The device did not meet the manufacturer’s stated accuracy specifications for pressure within its temperature-compensated operating range of –18 to 49 degrees Celsius or the USGS accuracy requirements of no more than 0.12 inch of water (0.01 foot of water) or 0.10 percent of reading, whichever is larger. The USGS accuracy requirements are routinely examined and reported when instruments are evaluated at the Hydrologic Instrumentation Facility. The estimated combined measurement uncertainty for the pressure cycling test was ±0.139 inch of water, and for temperature, the cycling test was ±0.127 inch of water for the three Infinities Loggers.

  6. Triaxial testing system for pressure core analysis using image processing technique

    NASA Astrophysics Data System (ADS)

    Yoneda, J.; Masui, A.; Tenma, N.; Nagao, J.

    2013-11-01

    In this study, a newly developed innovative triaxial testing system to investigate strength, deformation behavior, and/or permeability of gas hydrate bearing-sediments in deep sea is described. Transport of the pressure core from the storage chamber to the interior of the sealing sleeve of a triaxial cell without depressurization was achieved. An image processing technique was used to capture the motion and local deformation of a specimen in a transparent acrylic triaxial pressure cell and digital photographs were obtained at each strain level during the compression test. The material strength was successfully measured and the failure mode was evaluated under high confining and pore water pressures.

  7. Failure analysis and evaluation of a six cylinders crankshaft for marine diesel generator

    NASA Astrophysics Data System (ADS)

    Khaeroman, Haryadi, Gunawan Dwi; Ismail, R.; Kim, Seon Jin

    2017-01-01

    This paper discusses the failure of a diesel engine crankshaft of a four stroke 6 cylinders, used in a marine diesel generator. A correct analysis and evaluation of the dimension of the crankshaft are very essential to prevent failure of the crankshaft fracture and cracks. The crankshaft is liable to deformation due to misalignment of the main journals bearings. This article presents the result of crankshaft failure analysis by measuring the mean diameter of the rod journal and the main journal, on the wear, out of roundness, taper, etc. The measurement results must be compared with the acceptable value in the engine specification and manual service and also should follow the American Bureau of Shipping (ABS) guidance notes on propulsion shafting alignment. The measurement results of this study show that the main journal diameter of the third cylinder exhibits an excessive wear, 1.35 % above the permissible lowest rate. It also has a taper for 0.23 mm and out of roundness of 0.13 mm. The diameter of the rod journal indicates excessive wear, 1.06 % higher than the permissible lowest rate, the taper of 0.41 mm and out of roundness of 0.65 mm. The crankshaft warpage or run-out journal, the analysis of the crank web deflection are also evaluated and presented in this paper.

  8. Does Bilevel Positive Airway Pressure Improve Outcome of Acute Respiratory Failure after Open-heart Surgery?

    PubMed Central

    Elgebaly, Ahmed Said

    2017-01-01

    Background: Respiratory failure is of concern in the postoperative period after cardiac surgeries. Invasive ventilation (intermittent positive pressure ventilation [IPPV]) carries the risks and complications of intubation and mechanical ventilation (MV). Aims: Noninvasive positive pressure ventilation (NIPPV) is an alternative method and as effective as IPPV in treating insufficiency of respiration with less complications and minimal effects on respiratory and hemodynamic parameters next to open-heart surgery. Design: This is a prospective, randomized and controlled study. Materials and Methods: Forty-four patients scheduled for cardiac surgery were divided into two equal groups: Group I (IPPV) and Group II (NIPPV). Heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR), oxygen saturation (SpO2), arterial blood gas, weaning time, reintubation, tracheotomy rate, MV time, postoperative hospital stay, and ventilator-associated pneumonia during the period of hospital stay were recorded. Results: There was statistically significant difference in HR between groups with higher in Group I at 30 and 60 min and at 12 and 24 h. According to MAP, it started to increase significantly at hypoxemia, 15 min, 30 min, 4 h, 12 h, and at 24 h which was higher in Group I also. RR, PaO2, and PaCO2 showed significant higher in Group II at 15, 30, and 60 min and 4 h. According to pH, there was a significant difference between groups at 15, 30, and 60 min and at 4, 12, and 24 h postoperatively. SpO2 showed higher significant values in Group I at 15 and 30 min and at 12 h postoperatively. Duration of postoperative supportive ventilation was higher in Group I than that of Group II with statistically significant difference. Complications were statistically insignificant between Group I and Group II. Conclusion: Our study showed superiority of invasive over noninvasive mode of ventilator support. However, NIPPV (bilevel positive airway pressure) was proved to be a safe method

  9. Experimental evaluation of environmental scanning electron microscopes at high chamber pressure.

    PubMed

    Fitzek, H; Schroettner, H; Wagner, J; Hofer, F; Rattenberger, J

    2015-11-01

    In environmental scanning electron microscopy (ESEM) high pressure applications have become increasingly important. Wet or biological samples can be investigated without time-consuming sample preparation and potential artefacts from this preparation can be neglected. Unfortunately, the signal-to-noise ratio strongly decreases with increasing chamber pressure. To evaluate the high pressure performance of ESEM and to compare different electron microscopes, information about spatial resolution and detector type is not enough. On the one hand, the scattering of the primary electron beam increases, which vanishes the contrast in images; and on the other hand, the secondary electrons (SE) signal amplification decreases. The stagnation gas thickness (effective distance the beam has to travel through the imaging gas) as well as the SE detection system depend on the microscope and for a complete and serious evaluation of an ESEM or low vacuum SEM it is necessary to specify these two parameters. A method is presented to determine the fraction of scattered and unscattered electrons and to calculate the stagnation gas thickness (θ). To evaluate the high pressure performance of the SE detection system, a method is presented that allows for an analysis of a single image and the calculation of the signal-to-noise ratio of this image. All investigations are performed on an FEI ESEM Quanta 600 (field emission gun) and an FEI ESEM Quanta 200 (thermionic gun). These methods and measurements should represent opportunities for evaluating the high pressure performance of an ESEM. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  10. Time-dependent response of filamentary composite spherical pressure vessels

    NASA Technical Reports Server (NTRS)

    Dozier, J. D.

    1983-01-01

    A filamentary composite spherical pressure vessel is modeled as a pseudoisotropic (or transversely isotropic) composite shell, with the effects of the liner and fill tubes omitted. Equations of elasticity, macromechanical and micromechanical formulations, and laminate properties are derived for the application of an internally pressured spherical composite vessel. Viscoelastic properties for the composite matrix are used to characterize time-dependent behavior. Using the maximum strain theory of failure, burst pressure and critical strain equations are formulated, solved in the Laplace domain with an associated elastic solution, and inverted back into the time domain using the method of collocation. Viscoelastic properties of HBFR-55 resin are experimentally determined and a Kevlar/HBFR-55 system is evaluated with a FORTRAN program. The computed reduction in burst pressure with respect to time indicates that the analysis employed may be used to predict the time-dependent response of a filamentary composite spherical pressure vessel.

  11. Endoplasmic reticulum stress sensor protein kinase R-like endoplasmic reticulum kinase (PERK) protects against pressure overload-induced heart failure and lung remodeling.

    PubMed

    Liu, Xiaoyu; Kwak, Dongmin; Lu, Zhongbing; Xu, Xin; Fassett, John; Wang, Huan; Wei, Yidong; Cavener, Douglas R; Hu, Xinli; Hall, Jennifer; Bache, Robert J; Chen, Yingjie

    2014-10-01

    Studies have reported that development of congestive heart failure is associated with increased endoplasmic reticulum stress. Double stranded RNA-activated protein kinase R-like endoplasmic reticulum kinase (PERK) is a major transducer of the endoplasmic reticulum stress response and directly phosphorylates eukaryotic initiation factor 2α, resulting in translational attenuation. However, the physiological effect of PERK on congestive heart failure development is unknown. To study the effect of PERK on ventricular structure and function, we generated inducible cardiac-specific PERK knockout mice. Under unstressed conditions, cardiac PERK knockout had no effect on left ventricular mass, or its ratio to body weight, cardiomyocyte size, fibrosis, or left ventricular function. However, in response to chronic transverse aortic constriction, PERK knockout mice exhibited decreased ejection fraction, increased left ventricular fibrosis, enhanced cardiomyocyte apoptosis, and exacerbated lung remodeling in comparison with wild-type mice. PERK knockout also dramatically attenuated cardiac sarcoplasmic reticulum Ca(2+)-ATPase expression in response to aortic constriction. Our findings suggest that PERK is required to protect the heart from pressure overload-induced congestive heart failure. © 2014 American Heart Association, Inc.

  12. Contrasting effects of vasodilators on blood pressure and sodium balance in the hypertension of autonomic failure

    NASA Technical Reports Server (NTRS)

    Jordan, J.; Shannon, J. R.; Pohar, B.; Paranjape, S. Y.; Robertson, D.; Robertson, R. M.; Biaggioni, I.

    1999-01-01

    Supine hypertension, which is very common in patients with autonomic failure, limits the use of pressor agents and induces nighttime natriuresis. In 13 patients with severe orthostatic hypotension due to autonomic failure (7 women, 6 men, 72 +/- 3 yr) and supine hypertension, the effect of 30 mg nifedipine (n = 10) and 0.025 to 0.2 mg/h nitroglycerin patch (n = 11) on supine BP, renal sodium handling, and orthostatic tolerance was determined. Medications were given at 8 p.m.; patients stood up at 8 a.m. Nitroglycerin was removed at 6 a.m. Compared with placebo, nifedipine and nitroglycerin decreased systolic BP during the night by a maximum of 37 +/- 9 and 36 +/- 10 mmHg, respectively (P < 0.01). At 8 a.m., supine systolic BP was 23 +/- 7 mmHg lower with nifedipine than with placebo (P < 0.05), but was similar with nitroglycerin and placebo. Sodium excretion during the night was not reduced with nitroglycerin (0.13 +/- 0.02 mmol/mg creatinine [Cr] versus 0.15 +/- 0.03 mmol/mg Cr with placebo), but it was increased with nifedipine (0.35 +/- 0.06 mmol/mg Cr versus 0.13 +/- 0.02 mmol/mg Cr with placebo, P < 0.05). Nifedipine but not nitroglycerin worsened orthostatic hypotension in the morning. It is concluded that nifedipine and transdermal nitroglycerin are effective in controlling supine hypertension in patients with autonomic failure. However, nifedipine has a prolonged depressor effect and worsens orthostatic hypotension in the morning. The decrease in pressure natriuresis that would be expected with the substantial decrease in BP obtained with nitroglycerin and nifedipine may be offset by a direct effect of both drugs on renal sodium handling.

  13. Failure analysis of braided U-shaped metal bellows flexible hoses

    NASA Astrophysics Data System (ADS)

    Pierce, Stephen O.

    Most of the research performed extensively reviews the effects of non-reinforced metal bellows and their pressurized characteristics. However, the majority of flex hoses are manufactured with reinforcement by the means of interweaved wire braids. For this research, the outer braid reinforced metal bellows flex hoses will be examined for their failure at differing lengths. The relationship with the bellows expansion joints is such that as the length of the flex hoses increases, the pressure at which squirm occurs decreases. As such, for the testing being performed, the same approach to failure is expected. As the length of the flex hose increases, it is predicted that the hose will fail at a decreasing pressure. Since the braid is the only thing that prevents the squirm from occurring, more of the load will be displaced from the bellows and into the braid. This will ultimately cause failure of the braid to occur at a lower pressure as the length of the hoses increase due to more of the load being transmitted from the bellows and into the braid.

  14. Prevention of Contrast-Induced Nephropathy by Central Venous Pressure-Guided Fluid Administration in Chronic Kidney Disease and Congestive Heart Failure Patients.

    PubMed

    Qian, Geng; Fu, Zhenhong; Guo, Jun; Cao, Feng; Chen, Yundai

    2016-01-11

    This study aimed to explore the hemodynamic index-guided hydration method for patients with congestive heart failure (CHF) and chronic kidney disease (CKD) to reduce the risk of contrast-induced nephropathy (CIN) and at the same time to avoid the acute heart failure. Patients at moderate or high risk for CIN should receive sufficient hydration before contrast application. This prospective, randomized, double-blind, comparative clinical trial enrolled 264 consecutive patients with CKD and CHF undergoing coronary procedures. These patients were randomly assigned to either central venous pressure (CVP)-guided hydration group (n = 132) or the standard hydration group (n = 132). In the CVP-guided group, the hydration infusion rate was dynamically adjusted according to CVP level every hour. CIN was defined as an absolute increase in serum creatinine (SCr) >0.5 mg/dl (44.2 μmol/l) or a relative increase >25% compared with baseline SCr. Baseline characteristics were well-matched between the 2 groups. The total mean volume of isotonic saline administered in the CVP-guided hydration group was significantly higher than the control group (1,827 ± 497 ml vs. 1,202 ± 247 ml; p < 0.001). CIN occurred less frequently in CVP-guided hydration group than the control group (15.9% vs. 29.5%; p = 0.006). The incidences of acute heart failure during the hydration did not differ between the 2 groups (3.8% vs. 3.0%; p = 0.500). CVP-guided fluid administration can safely and effectively reduce the risk of CIN in patients with CKD and CHF. (Central Venous Pressure Guided Hydration Prevention for Contrast-Induced Nephropathy; NCT02405377). Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  15. PCI fuel failure analysis: a report on a cooperative program undertaken by Pacific Northwest Laboratory and Chalk River Nuclear Laboratories.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mohr, C.L.; Pankaskie, P.J.; Heasler, P.G.

    Reactor fuel failure data sets in the form of initial power (P/sub i/), final power (P/sub f/), transient increase in power (..delta..P), and burnup (Bu) were obtained for pressurized heavy water reactors (PHWRs), boiling water reactors (BWRs), and pressurized water reactors (PWRs). These data sets were evaluated and used as the basis for developing two predictive fuel failure models, a graphical concept called the PCI-OGRAM, and a nonlinear regression based model called PROFIT. The PCI-OGRAM is an extension of the FUELOGRAM developed by AECL. It is based on a critical threshold concept for stress dependent stress corrosion cracking. The PROFITmore » model, developed at Pacific Northwest Laboratory, is the result of applying standard statistical regression methods to the available PCI fuel failure data and an analysis of the environmental and strain rate dependent stress-strain properties of the Zircaloy cladding.« less

  16. Docosahexaenoic acid supplementation alters key properties of cardiac mitochondria and modestly attenuates development of left ventricular dysfunction in pressure overload-induced heart failure.

    PubMed

    Dabkowski, Erinne R; O'Connell, Kelly A; Xu, Wenhong; Ribeiro, Rogerio F; Hecker, Peter A; Shekar, Kadambari Chandra; Daneault, Caroline; Des Rosiers, Christine; Stanley, William C

    2013-12-01

    Supplementation with the n3 polyunsaturated fatty acid docosahexaenoic acid (DHA) is beneficial in heart failure patients, however the mechanisms are unclear. DHA is incorporated into membrane phospholipids, which may prevent mitochondrial dysfunction. Thus we assessed the effects of DHA supplementation on cardiac mitochondria and the development of heart failure caused by aortic pressure overload. Pathological cardiac hypertrophy was generated in rats by thoracic aortic constriction. Animals were fed either a standard diet or were supplemented with DHA (2.3 % of energy intake). After 14 weeks, heart failure was evident by left ventricular hypertrophy and chamber enlargement compared to shams. Left ventricle fractional shortening was unaffected by DHA treatment in sham animals (44.1 ± 1.6 % vs. 43.5 ± 2.2 % for standard diet and DHA, respectively), and decreased with heart failure in both treatment groups, but to a lesser extent in DHA treated animals (34.9 ± 1.7 %) than with the standard diet (29.7 ± 1.5 %, P < 0.03). DHA supplementation increased DHA content in mitochondrial phospholipids and decreased membrane viscosity. Myocardial mitochondrial oxidative capacity was decreased by heart failure and unaffected by DHA. DHA treatment enhanced Ca(2+) uptake by subsarcolemmal mitochondria in both sham and heart failure groups. Further, DHA lessened Ca(2+)-induced mitochondria swelling, an index of permeability transition, in heart failure animals. Heart failure increased hydrogen peroxide-induced mitochondrial permeability transition compared to sham, which was partially attenuated in interfibrillar mitochondria by treatment with DHA. DHA decreased mitochondrial membrane viscosity and accelerated Ca(2+) uptake, and attenuated susceptibility to mitochondrial permeability transition and development of left ventricular dysfunction.

  17. Radiosonde pressure sensor performance - Evaluation using tracking radars

    NASA Technical Reports Server (NTRS)

    Parsons, C. L.; Norcross, G. A.; Brooks, R. L.

    1984-01-01

    The standard balloon-borne radiosonde employed for synoptic meteorology provides vertical profiles of temperature, pressure, and humidity as a function of elapsed time. These parameters are used in the hypsometric equation to calculate the geopotential altitude at each sampling point during the balloon's flight. It is important that the vertical location information be accurate. The present investigation was conducted with the objective to evaluate the altitude determination accuracy of the standard radiosonde throughout the entire balloon profile. The tests included two other commercially available pressure sensors to see if they could provide improved accuracy in the stratosphere. The pressure-measuring performance of standard baroswitches, premium baroswitches, and hypsometers in balloon-borne sondes was correlated with tracking radars. It was found that the standard and premium baroswitches perform well up to about 25 km altitude, while hypsometers provide more reliable data above 25 km.

  18. Evaluation of the suitability of root cause analysis frameworks for the investigation of community-acquired pressure ulcers: a systematic review and documentary analysis.

    PubMed

    McGraw, Caroline; Drennan, Vari M

    2015-02-01

    To evaluate the suitability of root cause analysis frameworks for the investigation of community-acquired pressure ulcers. The objective was to identify the extent to which these frameworks take account of the setting where the ulcer originated as being the person's home rather than a hospital setting. Pressure ulcers involving full-thickness skin loss are increasingly being regarded as indicators of nursing patient safety failure, requiring investigation using root cause analysis frameworks. Evidence suggests that root cause analysis frameworks developed in hospital settings ignore the unique dimensions of risk in home healthcare settings. A systematic literature review and documentary analysis of frameworks used to investigate community-acquired grade three and four pressure ulcers by home nursing services in England. No published papers were identified for inclusion in the review. Fifteen patient safety investigative frameworks were collected and analysed. Twelve of the retrieved frameworks were intended for the investigation of community-acquired pressure ulcers; seven of which took account of the setting where the ulcer originated as being the patient's home. This study provides evidence to suggest that many of the root cause analysis frameworks used to investigate community-acquired pressure ulcers in England are unsuitable for this purpose. This study provides researchers and practitioners with evidence of the need to develop appropriate home nursing root cause analysis frameworks to investigate community-acquired pressure ulcers. © 2014 John Wiley & Sons Ltd.

  19. Become the PPUPET Master: Mastering Pressure Ulcer Risk Assessment With the Pediatric Pressure Ulcer Prediction and Evaluation Tool (PPUPET).

    PubMed

    Sterken, David J; Mooney, JoAnn; Ropele, Diana; Kett, Alysha; Vander Laan, Karen J

    2015-01-01

    Hospital acquired pressure ulcers (HAPU) are serious, debilitating, and preventable complications in all inpatient populations. Despite evidence of the development of pressure ulcers in the pediatric population, minimal research has been done. Based on observations gathered during quarterly HAPU audits, bedside nursing staff recognized trends in pressure ulcer locations that were not captured using current pressure ulcer risk assessment tools. Together, bedside nurses and nursing leadership created and conducted multiple research studies to investigate the validity and reliability of the Pediatric Pressure Ulcer Prediction and Evaluation Tool (PPUPET). Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Systematic review of non-invasive positive pressure ventilation for chronic respiratory failure.

    PubMed

    Hannan, Liam M; Dominelli, Giulio S; Chen, Yi-Wen; Darlene Reid, W; Road, Jeremy

    2014-02-01

    This systematic review examined the effect of non-invasive positive pressure ventilation (NIPPV) on patient reported outcomes (PROs) and survival for individuals with or at risk of chronic respiratory failure (CRF). Randomised controlled trials (RCTs) and prospective non-randomised studies in those treated with NIPPV for CRF were identified from electronic databases, reference lists and grey literature. Diagnostic groups included in the review were amyotrophic lateral sclerosis/motor neuron disease (ALS/MND), Duchenne muscular dystrophy (DMD), restrictive thoracic disease (RTD) and obesity hypoventilation syndrome (OHS). Eighteen studies were included and overall study quality was weak. Those with ALS/MND had improved somnolence and fatigue as well as prolonged survival with NIPPV. For OHS, improvements in somnolence and fatigue, dyspnoea and sleep quality were demonstrated, while for RTD, measures of dyspnoea, sleep quality, physical function and health, mental and emotional health and social function improved. There was insufficient evidence to form conclusions regarding the effect of NIPPV for those with DMD. This review has demonstrated that NIPPV influences PROs differently depending on the underlying cause of CRF. These findings may provide assistance to patients and clinicians to determine the relative costs and benefits of NIPPV therapy and also highlight areas in need of further research. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Pressure Safety: Advanced Live 11459

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Glass, George

    Many Los Alamos National Laboratory (LANL) operations use pressure equipment and systems. Failure to follow proper procedures when designing or operating pressure systems can result in injuries to personnel and damage to equipment and/or the environment. This manual presents an overview of the requirements and recommendations that address the safe design and operation of pressure systems at LANL.

  2. Noninvasive positive pressure ventilation for acute respiratory failure in delirious patients: understudied, underreported, or underappreciated? A systematic review and meta-analysis.

    PubMed

    Charlesworth, Michael; Elliott, Mark W; Holmes, John D

    2012-12-01

    We performed a systematic review and meta-analysis of the literature to determine the prevalence of delirium in patients receiving noninvasive positive pressure ventilation (NPPV) for acute respiratory failure and to quantify the prognostic impact of delirium with respect to NPPV failure. We searched the databases EMBASE (1996 to present), MEDLINE (1996 to present), PsycINFO(®) (2002 to present) and CINAHL (1992 to present). A Google™ search and hand searching of bibliographies or relevant articles were also performed. We searched for prospective observational studies conducted in a setting where patients with acute respiratory failure receiving NPPV were screened for delirium. All authors independently assessed references for inclusion and extracted data. Information was collated regarding study design, baseline characteristics of included patients, and the prevalence of delirium. Where prognostic information regarding NPPV failure was reported, a risk ratio for the association between delirium and NPPV failure was derived. These values were pooled in the meta-analysis. Three articles were retrieved by the search strategy. These included 239 patients receiving noninvasive ventilation who were assessed for delirium. The prevalence of delirium was recorded at between 33 and 38 % with a pooled prevalence of 37 %. Two studies reported prognostic data and the risk ratios for noninvasive ventilation failure in delirium were calculated as 1.79 (95 % CI 1.09-2.94) and 3.28 (95 % CI 1.60-6.73). A meta-analysis was performed and the pooled risk ratio was found to be 2.12 (95 % CI 1.41-3.18). The data in this context was scarce and of low quality. A diagnosis of delirium was made in 9 patients and inferred in 80. Despite the current lack of high-quality data and studies, the high reported prevalence of delirium and the association with noninvasive ventilation failure lends support for more awareness amongst health-care professionals and more routine screening. More

  3. EVALUATION OF SAFETY IN A RADIATION ONCOLOGY SETTING USING FAILURE MODE AND EFFECTS ANALYSIS

    PubMed Central

    Ford, Eric C.; Gaudette, Ray; Myers, Lee; Vanderver, Bruce; Engineer, Lilly; Zellars, Richard; Song, Danny Y.; Wong, John; DeWeese, Theodore L.

    2013-01-01

    Purpose Failure mode and effects analysis (FMEA) is a widely used tool for prospectively evaluating safety and reliability. We report our experiences in applying FMEA in the setting of radiation oncology. Methods and Materials We performed an FMEA analysis for our external beam radiation therapy service, which consisted of the following tasks: (1) create a visual map of the process, (2) identify possible failure modes; assign risk probability numbers (RPN) to each failure mode based on tabulated scores for the severity, frequency of occurrence, and detectability, each on a scale of 1 to 10; and (3) identify improvements that are both feasible and effective. The RPN scores can span a range of 1 to 1000, with higher scores indicating the relative importance of a given failure mode. Results Our process map consisted of 269 different nodes. We identified 127 possible failure modes with RPN scores ranging from 2 to 160. Fifteen of the top-ranked failure modes were considered for process improvements, representing RPN scores of 75 and more. These specific improvement suggestions were incorporated into our practice with a review and implementation by each department team responsible for the process. Conclusions The FMEA technique provides a systematic method for finding vulnerabilities in a process before they result in an error. The FMEA framework can naturally incorporate further quantification and monitoring. A general-use system for incident and near miss reporting would be useful in this regard. PMID:19409731

  4. Exercise duration and peak systolic blood pressure are predictive of mortality in ambulatory patients with mild-moderate chronic heart failure.

    PubMed

    Williams, Simon G; Jackson, Mark; Ng, Leong L; Barker, Diane; Patwala, Ashish; Tan, Lip-Bun

    2005-01-01

    It is a prevailing concept in chronic heart failure (CHF) that ventricular remodelling (evaluated via imaging) and neurohormonal activation (via biomarkers) exert major influences, such that the need to subject patients to haemodynamic evaluations and exercise testing has been questioned. We sought to investigate whether exercise and haemodynamic parameters lack independent prognostic value in a cohort of unselected ambulatory patients with mild-moderate CHF. Eighty-five consecutive patients with stable CHF in New York Heart Association functional classes I-IV, aged 55 +/- 12 years, 84% males, left ventricular ejection fraction (LVEF) 37 +/- 15%, participated in this study. Survivors were followed for a median of 5.08 years. All subjects underwent cardiopulmonary exercise testing to measure standard parameters including peak oxygen consumption, exercise duration and blood pressure. A sample of venous blood was taken to determine the N-terminal pro-brain natriuretic peptide (N-BNP) level. Echocardiography was performed at rest to measure LVEF. Predictors of mortality were sought using the Cox proportional hazards model. All-cause mortality was 19% (16 deaths, 95% CI 11-29%). Age and LVEF did not independently predict mortality. Although various parameters including New York Heart Association class, peak oxygen consumption and N-BNP level were all predictive of outcome on univariate analysis, multivariate analysis identified reduced exercise duration and peak systolic blood pressure (SBP) to be the only independent predictors of all-cause mortality. Hazard ratios of 0.78 (95% CI 0.65-0.93, p = 0.007) and 0.79 (95% CI 0.66-0.95, p = 0.01) were associated with an increase in exercise duration of 1 min and 10 mm Hg peak SBP, respectively. Two simple parameters (exercise duration and peak SBP) that are easily measured by standard exercise testing are the strongest independent predictors of mortality which outperform LVEF and N-BNP in ambulatory patients with mild

  5. Cheyne-stokes respiration in patients with heart failure.

    PubMed

    AlDabal, Laila; BaHammam, Ahmed S

    2010-01-01

    Cheyne-Stokes respiration (CSR) is a form of central sleep-disordered breathing (SDB) in which there are cyclical fluctuations in breathing that lead to periods of central apneas/hypopnea, which alternate with periods of hyperpnea. The crescendo-decrescendo pattern of respiration in CSR is a compensation for the changing levels of blood oxygen and carbon dioxide. Severe congestive heart failure seems to be the most important risk factor for the development of CSR. A number of pathophysiologic changes, such as sleep disruption, arousals, hypoxemia-reoxygenation, hypercapnia/hypocapnia, and changes in intrathoracic pressure have harmful effects on the cardiovascular system, and the presence of CSR is associated with increased mortality and morbidity in subjects with variable degrees of heart failure. The management of CSR involves optimal control of underlying heart failure, oxygen therapy, and positive airway pressure support. In this review, we initially define and describe the epidemiology of central sleep apnea (CSA) and CSR, its pathogenesis, clinical presentation, diagnostic methods, and then discuss the recent developments in the management in patients with heart failure.

  6. Evaluation of runner cone extension to dampen pressure pulsations in a Francis model turbine

    NASA Astrophysics Data System (ADS)

    Gogstad, Peter Joachim; Dahlhaug, Ole Gunnar

    2016-11-01

    Today's energy market has a high demand of flexibility due to introduction of other intermittent renewables as wind and solar. To ensure a steady power supply, hydro turbines are often forced to operate more at part load conditions. Originally, turbines were built for steady operation around the best efficiency point. The demand of flexibility, combined with old designs has showed an increase in turbines having problems with hydrodynamic instabilities such as pressure pulsations. Different methods have been investigated to mitigate pressure pulsations. Air injection shows a significant reduction of pressure pulsation amplitudes. However, installation of air injection requires extra piping and a compressor. Investigation of other methods such as shaft extension shows promising results for some operational points, but may significantly reduce the efficiency of the turbine at other operational points. The installation of an extension of the runner cone has been investigated at NTNU by Vekve in 2004. This has resulted in a cylindrical extension at Litjfossen Power Plant in Norway, where the bolt suffered mechanical failure. This indicates high amplitude pressure pulsations in the draft tube centre. The high pressure pulsation amplitudes are believed to be related to high tangential velocity in the draft tube. The mentioned runner cone extension has further been developed to a freely rotating extension. The objective is to reduce the tangential velocity in the draft tube and thereby the pressure pulsation amplitudes.

  7. Evaluation of a Progressive Failure Analysis Methodology for Laminated Composite Structures

    NASA Technical Reports Server (NTRS)

    Sleight, David W.; Knight, Norman F., Jr.; Wang, John T.

    1997-01-01

    A progressive failure analysis methodology has been developed for predicting the nonlinear response and failure of laminated composite structures. The progressive failure analysis uses C plate and shell elements based on classical lamination theory to calculate the in-plane stresses. Several failure criteria, including the maximum strain criterion, Hashin's criterion, and Christensen's criterion, are used to predict the failure mechanisms. The progressive failure analysis model is implemented into a general purpose finite element code and can predict the damage and response of laminated composite structures from initial loading to final failure.

  8. Congestive renal failure: the pathophysiology and treatment of renal venous hypertension.

    PubMed

    Ross, Edward A

    2012-12-01

    Longstanding experimental evidence supports the role of renal venous hypertension in causing kidney dysfunction and "congestive renal failure." A focus has been heart failure, in which the cardiorenal syndrome may partly be due to high venous pressure, rather than traditional mechanisms involving low cardiac output. Analogous diseases are intra-abdominal hypertension and renal vein thrombosis. Proposed pathophysiologic mechanisms include reduced transglomerular pressure, elevated renal interstitial pressure, myogenic and neural reflexes, baroreceptor stimulation, activation of sympathetic nervous and renin angiotensin aldosterone systems, and enhanced proinflammatory pathways. Most clinical trials have addressed the underlying condition rather than venous hypertension per se. Interpreting the effects of therapeutic interventions on renal venous congestion are therefore problematic because of such confounders as changes in left ventricular function, cardiac output, and blood pressure. Nevertheless, there is preliminary evidence from small studies of intense medical therapy or extracorporeal ultrafiltration for heart failure that there can be changes to central venous pressure that correlate inversely with renal function, independently from the cardiac index. Larger more rigorous trials are needed to definitively establish under what circumstances conventional pharmacologic or ultrafiltration goals might best be directed toward central venous pressures rather than left ventricular or cardiac output parameters. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. [Evaluation of the cost of treating pressure ulcers in hospitalized patients using industrialized dressings].

    PubMed

    Lima, Angela Cristina Beck; Guerra, Diana Mendonça

    2011-01-01

    This work evaluated wound dresses used in the Neurosurgery Department of Restauração Hospital: polyurethane, hydrogel and activated carbon wound dresses and hydrogel with alginate used for pressure ulcer care. This work aimed to identify a critical factor that increases demand and cost of wound dresses. The evaluation conducted at the Neurosurgery Department identified individuals at risk of pressure ulcer development. Sixty-two patients were evaluated and the prevalence of pressure ulcer was 22.6% according to the Braden scale. Comparative evaluation between patients that didn't receive preventive measures and others that received, showed that the average daily cost of hospitalization for the first group was 45% higher than the mean for the second group. The Wilcoxon-Mann-Withiney test compared the population at risk to develop pressure ulcer and population at low risk showing that the evaluation of Braden Scale scores between the groups presents statistically significant differences and confidence limits of 95%. Pressure ulcer is a key quality indicator in health services.It is possible to reduce costs and offer higher quality public health services by implementing a training program of nursing staff using a preventive measure protocol based on a test to evaluate risk as Braden Scale.

  10. Seat pressure measurement technologies: considerations for their evaluation.

    PubMed

    Gyi, D E; Porter, J M; Robertson, N K

    1998-04-01

    Interface pressure measurement has generated interest in the automotive industry as a technique which could be used in the prediction of driver discomfort for various car seat designs, and provide designers and manufacturers with rapid information early on in the design process. It is therefore essential that the data obtained are of the highest quality, relevant and have some quantitative meaning. Exploratory experimental work carried out with the commercially available Talley Pressure Monitor is outlined. This led to a better understanding of the strengths and weaknesses of this system and the re-design of the sensor matrix. Such evaluation, in the context of the actual experimental environment, is considered essential.

  11. X-33 LH2 Tank Failure Investigation Findings

    NASA Technical Reports Server (NTRS)

    Niedermeyer, Mindy; Clinton, R. G., Jr. (Technical Monitor)

    2000-01-01

    This presentation focuses on the tank history, test objectives, failure description, investigation and conclusions. The test objectives include verify structural integrity at 105% expected flight load limit varying the following parameters: cryogenic temperature; internal pressure; and mechanical loading. The Failure description includes structural component of the aft body, quad-lobe design, and sandwich - honeycomb graphite epoxy construction.

  12. Betterment, undermining, support and distortion: A heuristic model for the analysis of pressure on evaluators.

    PubMed

    Pleger, Lyn; Sager, Fritz

    2016-09-18

    Evaluations can only serve as a neutral evidence base for policy decision-making as long as they have not been altered along non-scientific criteria. Studies show that evaluators are repeatedly put under pressure to deliver results in line with given expectations. The study of pressure and influence to misrepresent findings is hence an important research strand for the development of evaluation praxis. A conceptual challenge in the area of evaluation ethics research is the fact that pressure can be not only negative, but also positive. We develop a heuristic model of influence on evaluations that does justice to this ambivalence of influence: the BUSD-model (betterment, undermining, support, distortion). The model is based on the distinction of two dimensions, namely 'explicitness of pressure' and 'direction of influence'. We demonstrate how the model can be applied to understand pressure and offer a practical tool to distinguish positive from negative influence in the form of three so-called differentiators (awareness, accordance, intention). The differentiators comprise a practical component by assisting evaluators who are confronted with influence. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Choline Diet and Its Gut Microbe-Derived Metabolite, Trimethylamine N-Oxide, Exacerbate Pressure Overload-Induced Heart Failure.

    PubMed

    Organ, Chelsea L; Otsuka, Hiroyuki; Bhushan, Shashi; Wang, Zeneng; Bradley, Jessica; Trivedi, Rishi; Polhemus, David J; Tang, W H Wilson; Wu, Yuping; Hazen, Stanley L; Lefer, David J

    2016-01-01

    Trimethylamine N-oxide (TMAO), a gut microbe-dependent metabolite of dietary choline and other trimethylamine-containing nutrients, is both elevated in the circulation of patients having heart failure and heralds worse overall prognosis. In animal studies, dietary choline or TMAO significantly accelerates atherosclerotic lesion development in ApoE-deficient mice, and reduction in TMAO levels inhibits atherosclerosis development in the low-density lipoprotein receptor knockout mouse. C57BL6/J mice were fed either a control diet, a diet containing choline (1.2%) or a diet containing TMAO (0.12%) starting 3 weeks before surgical transverse aortic constriction. Mice were studied for 12 weeks after transverse aortic constriction. Cardiac function and left ventricular structure were monitored at 3-week intervals using echocardiography. Twelve weeks post transverse aortic constriction, myocardial tissues were collected to evaluate cardiac and vascular fibrosis, and blood samples were evaluated for cardiac brain natriuretic peptide, choline, and TMAO levels. Pulmonary edema, cardiac enlargement, and left ventricular ejection fraction were significantly (P<0.05, each) worse in mice fed either TMAO- or choline-supplemented diets when compared with the control diet. In addition, myocardial fibrosis was also significantly greater (P<0.01, each) in the TMAO and choline groups relative to controls. Heart failure severity is significantly enhanced in mice fed diets supplemented with either choline or the gut microbe-dependent metabolite TMAO. The present results suggest that additional studies are warranted examining whether gut microbiota and the dietary choline → TMAO pathway contribute to increased heart failure susceptibility. © 2015 American Heart Association, Inc.

  14. Development and evaluation of a composite risk score to predict kidney transplant failure.

    PubMed

    Moore, Jason; He, Xiang; Shabir, Shazia; Hanvesakul, Rajesh; Benavente, David; Cockwell, Paul; Little, Mark A; Ball, Simon; Inston, Nicholas; Johnston, Atholl; Borrows, Richard

    2011-05-01

    Although risk factors for kidney transplant failure are well described, prognostic risk scores to estimate risk in prevalent transplant recipients are limited. Development and validation of risk-prediction instruments. The development data set included 2,763 prevalent patients more than 12 months posttransplant enrolled into the LOTESS (Long Term Efficacy and Safety Surveillance) Study. The validation data set included 731 patients who underwent transplant at a single UK center. Estimated glomerular filtration rate (eGFR) and other risk factors were evaluated using Cox regression. Scores for death-censored and overall transplant failure were based on the summed hazard ratios for baseline predictor variables. Predictive performance was assessed using calibration (Hosmer-Lemeshow statistic), discrimination (C statistic), and clinical reclassification (net reclassification improvement) compared with eGFR alone. In the development data set, 196 patients died and another 225 experienced transplant failure. eGFR, recipient age, race, serum urea and albumin levels, declining eGFR, and prior acute rejection predicted death-censored transplant failure. eGFR, recipient age, sex, serum urea and albumin levels, and declining eGFR predicted overall transplant failure. In the validation data set, 44 patients died and another 101 experienced transplant failure. The weighted scores comprising these variables showed adequate discrimination and calibration for death-censored (C statistic, 0.83; 95% CI, 0.75-0.91; Hosmer-Lemeshow χ(2)P = 0.8) and overall (C statistic, 0.70; 95% CI, 0.64-0.77; Hosmer-Lemeshow χ(2)P = 0.5) transplant failure. However, the scores failed to reclassify risk compared with eGFR alone (net reclassification improvements of 7.6% [95% CI, -0.2 to 13.4; P = 0.09] and 4.3% [95% CI, -2.7 to 11.8; P = 0.3] for death-censored and overall transplant failure, respectively). Retrospective analysis of predominantly cyclosporine-treated patients; limited study size and

  15. Thermoplastic fusion bonding using a pressure-assisted boiling point control system.

    PubMed

    Park, Taehyun; Song, In-Hyouk; Park, Daniel S; You, Byoung Hee; Murphy, Michael C

    2012-08-21

    A novel thermoplastic fusion bonding method using a pressure-assisted boiling point (PABP) control system was developed to apply precise temperatures and pressures during bonding. Hot embossed polymethyl methacrylate (PMMA) components containing microchannels were sealed using the PABP system. Very low aspect ratio structures (AR = 1/100, 10 μm in depth and 1000 μm in width) were successfully sealed without collapse or deformation. The integrity and strength of the bonds on the sealed PMMA devices were evaluated using leakage and rupture tests; no leaks were detected and failure during the rupture tests occurred at pressures greater than 496 kPa. The PABP system was used to seal 3D shaped flexible PMMA devices successfully.

  16. Failure of a gas well to respond to a foam hydraulic fracturing treatment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rauscher, B.D.

    1996-12-31

    Well No. 1 (not the real name of the well) is not producing gas at maximum capacity following a foam hydraulic fracturing treatment performed upon completion of the well in 1987. The failure of the stimulation treatment, which has affected other wells throughout the field, was due to a combination of three factors: (1) downward fracture growth and proppant settling during injection (2) embedment due to a high pressure drawdown in the wellbore during flowback procedures, and (3) poor cleanup of the fracture fluid due to high capillary pressures. The following are recommendations to help improve future fracturing treatments throughoutmore » the field: (1) Fracture at lower treating pressures; (2) Improve perforating techniques; (3) Change flowback procedures; and (4) Evaluate using N{sub 2} as a fracture fluid.« less

  17. Use of failure mode and effects analysis for proactive identification of communication and handoff failures from organ procurement to transplantation.

    PubMed

    Steinberger, Dina M; Douglas, Stephen V; Kirschbaum, Mark S

    2009-09-01

    A multidisciplinary team from the University of Wisconsin Hospital and Clinics transplant program used failure mode and effects analysis to proactively examine opportunities for communication and handoff failures across the continuum of care from organ procurement to transplantation. The team performed a modified failure mode and effects analysis that isolated the multiple linked, serial, and complex information exchanges occurring during the transplantation of one solid organ. Failure mode and effects analysis proved effective for engaging a diverse group of persons who had an investment in the outcome in analysis and discussion of opportunities to improve the system's resilience for avoiding errors during a time-pressured and complex process.

  18. Arterial blood pressure response to heavy resistance exercise.

    PubMed

    MacDougall, J D; Tuxen, D; Sale, D G; Moroz, J R; Sutton, J R

    1985-03-01

    The purpose of this study was to record the blood pressure response to heavy weight-lifting exercise in five experienced body builders. Blood pressure was directly recorded by means of a capacitance transducer connected to a catheter in the brachial artery. Intrathoracic pressure with the Valsalva maneuver was recorded as mouth pressure by having the subject maintain an open glottis while expiring against a column of Hg during the lifts. Exercises included single-arm curls, overhead presses, and both double- and single-leg presses performed to failure at 80, 90, 95, and 100% of maximum. Systolic and diastolic blood pressures rose rapidly to extremely high values during the concentric contraction phase for each lift and declined with the eccentric contraction. The greatest peak pressures occurred during the double-leg press where the mean value for the group was 320/250 mmHg, with pressures in one subject exceeding 480/350 mmHg. Peak pressures with the single-arm curl exercise reached a mean group value of 255/190 mmHg when repetitions were continued to failure. Mouth pressures of 30-50 Torr during a single maximum lift, or as subjects approached failure with a submaximal weight, indicate that a portion of the observed increase in blood pressure was caused by a Valsalva maneuver. It was concluded that when healthy young subjects perform weight-lifting exercises the mechanical compression of blood vessels combines with a potent pressor response and a Valsalva response to produce extreme elevations in blood pressure. Pressures are extreme even when exercise is performed with a relatively small muscle mass.

  19. Echocardiographic evaluation during weaning from mechanical ventilation.

    PubMed

    Schifelbain, Luciele Medianeira; Vieira, Silvia Regina Rios; Brauner, Janete Salles; Pacheco, Deise Mota; Naujorks, Alexandre Antonio

    2011-01-01

    Echocardiographic, electrocardiographic and other cardiorespiratory variables can change during weaning from mechanical ventilation. To analyze changes in cardiac function, using Doppler echocardiogram, in critical patients during weaning from mechanical ventilation, using two different weaning methods: pressure support ventilation and T-tube; and comparing patient subgroups: success vs. failure in weaning. Randomized crossover clinical trial including patients under mechanical ventilation for more than 48 h and considered ready for weaning. Cardiorespiratory variables, oxygenation, electrocardiogram and Doppler echocardiogram findings were analyzed at baseline and after 30 min in pressure support ventilation and T-tube. Pressure support ventilation vs. T-tube and weaning success vs. failure were compared using ANOVA and Student's t-test. The level of significance was p<0.05. Twenty-four adult patients were evaluated. Seven patients failed at the first weaning attempt. No echocardiographic or electrocardiographic differences were observed between pressure support ventilation and T-tube. Weaning failure patients presented increases in left atrium, intraventricular septum thickness, posterior wall thickness and diameter of left ventricle and shorter isovolumetric relaxation time. Successfully weaned patients had higher levels of oxygenation. No differences were observed between Doppler echocardiographic variables and electrocardiographic and other cardiorespiratory variables during pressure support ventilation and T-tube. However cardiac structures were smaller, isovolumetric relaxation time was larger, and oxygenation level was greater in successfully weaned patients.

  20. Echocardiographic evaluation during weaning from mechanical ventilation

    PubMed Central

    Schifelbain, Luciele Medianeira; Vieira, Silvia Regina Rios; Brauner, Janete Salles; Pacheco, Deise Mota; Naujorks, Alexandre Antonio

    2011-01-01

    INTRODUCTION: Echocardiographic, electrocardiographic and other cardiorespiratory variables can change during weaning from mechanical ventilation. OBJECTIVES: To analyze changes in cardiac function, using Doppler echocardiogram, in critical patients during weaning from mechanical ventilation, using two different weaning methods: pressure support ventilation and T‐tube; and comparing patient subgroups: success vs. failure in weaning. METHODS: Randomized crossover clinical trial including patients under mechanical ventilation for more than 48 h and considered ready for weaning. Cardiorespiratory variables, oxygenation, electrocardiogram and Doppler echocardiogram findings were analyzed at baseline and after 30 min in pressure support ventilation and T‐tube. Pressure support ventilation vs. T‐tube and weaning success vs. failure were compared using ANOVA and Student's t‐test. The level of significance was p<0.05. RESULTS: Twenty‐four adult patients were evaluated. Seven patients failed at the first weaning attempt. No echocardiographic or electrocardiographic differences were observed between pressure support ventilation and T‐tube. Weaning failure patients presented increases in left atrium, intraventricular septum thickness, posterior wall thickness and diameter of left ventricle and shorter isovolumetric relaxation time. Successfully weaned patients had higher levels of oxygenation. CONCLUSION: No differences were observed between Doppler echocardiographic variables and electrocardiographic and other cardiorespiratory variables during pressure support ventilation and T‐tube. However cardiac structures were smaller, isovolumetric relaxation time was larger, and oxygenation level was greater in successfully weaned patients. PMID:21437445

  1. Studies and analyses of the Space Shuttle Main Engine: SSME failure data review, diagnostic survey and SSME diagnostic evaluation

    NASA Technical Reports Server (NTRS)

    Glover, R. C.; Kelley, B. A.; Tischer, A. E.

    1986-01-01

    The results of a review of the Space Shuttle Main Engine (SSME) failure data for the period 1980 through 1983 are presented. The data was collected, evaluated, and ranked according to procedures established during this study. A number of conclusions and recommendations are made based upon this failure data review. The results of a state-of-the-art diagnostic survey are also presented. This survey covered a broad range of diagnostic sensors and techniques and the findings were evaluated for application to the SSME. Finally, a discussion of the initial activities for the on-going SSME diagnostic evaluation is included.

  2. First metatarsophalangeal joint arthrodesis: an evaluation of hardware failure.

    PubMed

    Bennett, Gordon L; Kay, David B; Sabatta, James

    2005-08-01

    First metatarsophalangeal joint (MTPJ) arthrodesis is commonly used for the treatment of a variety of conditions affecting the hallux. We used a method incorporating a ball-and-cup preparation of the first metatarsal and proximal phalanx, followed by fixation of the arthrodesis with a lag screw and a dorsal plate (Synthes Modular Hand Set). Ninety-five consecutive patients had first MTPJ arthrodesis using fixation with the Synthes Modular Hand Set. All patients were evaluated preoperatively, at regular intervals postoperatively, and at final followup. The American Orthopaedic Foot and Ankle Society (AOFAS) forefoot scoring system was used preoperatively and at final followup. Solid fusion occurred in 93 of 107 feet (86.9%). In the 14 that did not fuse, either the screws or plate, or both, broke. Ten of the 14 feet were symptomatic, but only three required further operative treatment. There were no hardware problems or failures in patients who had solid fusions. Preoperative AOFAS scores were improved after surgery in all patients. A solid first MTPJ fusion results in excellent function and pain relief, but the Synthes Modular Hand Set implants do not appear to be strong enough in all patients for this application; nonunion at the arthrodesis site and failure of hardware occurred in 13% of arthrodeses. We no longer recommend this implant for this application.

  3. Right ventricular effects of intracoronary delivery of mesenchymal stem cells (MSC) in an animal model of pressure overload heart failure.

    PubMed

    Molina, Ezequiel J; Palma, Jon; Gupta, Dipin; Gaughan, John P; Houser, Steven; Macha, Mahender

    2009-12-01

    In a rat model of left ventricular pressure overload hypertrophy with biventricular failure, we studied the effects of intracoronary delivery of mesenchymal stem cells (MCS) upon right ventricular hemodynamic performance, profiles of local inflammation and apoptosis, and determinants of extracellular matrix remodeling. Sprague-Dawley rats underwent aortic banding and were followed by echocardiography. After a decrease in left ventricular fractional shortening of 25% from the baseline (relative 50% reduction), animals were randomized to an intracoronary injection of MSC (n=28) or PBS (n=20). Right ventricular hemodynamic assessment and measurement of local inflammatory markers, proapoptotic factors, and determinants of extracellular matrix remodeling were performed on post-transplantation day 7, 14, 21 or 28. MSC injection improved right ventricular systolic function in the MSC group compared to the control group (mean+/-SD, max dP/dt 772+/-272 mm Hg/s vs. 392+/-132 at 28 days, P<0.01). Diastolic function was similarly improved (mean+/-SD, max -dP/dt -558+/-171 mm Hg/s vs. -327+/-131 at 28 days, P<0.05). Right ventricular levels of IL-1, IL-6, TNF-alpha, bax, bak and p38 were significantly decreased in the MSC treated animals. Expression of MMP-3, MMP-6, MMP-9, TIMP-1 and TIMP-3 declined in the MSC group compared with controls after 28 days. In this model of left ventricular pressure overload hypertrophy and biventricular failure, intracoronary delivery of MSC was associated with an improvement in the right ventricular hemodynamic performance, profiles of local inflammation and apoptosis, and determinants of extracellular matrix remodeling.

  4. Hypertension as a risk factor for heart failure.

    PubMed

    Kannan, Arun; Janardhanan, Rajesh

    2014-07-01

    Hypertension remains a significant risk factor for development of congestive heart failure CHF), with various mechanisms contributing to both systolic and diastolic dysfunction. The pathogenesis of myocardial changes includes structural remodeling, left ventricular hypertrophy, and fibrosis. Activation of the sympathetic nervous system and renin-angiotensin system is a key contributing factor of hypertension, and thus interventions that antagonize these systems promote regression of hypertrophy and heart failure. Control of blood pressure is of paramount importance in improving the prognosis of patients with heart failure.

  5. Study on Failure of Third-Party Damage for Urban Gas Pipeline Based on Fuzzy Comprehensive Evaluation.

    PubMed

    Li, Jun; Zhang, Hong; Han, Yinshan; Wang, Baodong

    2016-01-01

    Focusing on the diversity, complexity and uncertainty of the third-party damage accident, the failure probability of third-party damage to urban gas pipeline was evaluated on the theory of analytic hierarchy process and fuzzy mathematics. The fault tree of third-party damage containing 56 basic events was built by hazard identification of third-party damage. The fuzzy evaluation of basic event probabilities were conducted by the expert judgment method and using membership function of fuzzy set. The determination of the weight of each expert and the modification of the evaluation opinions were accomplished using the improved analytic hierarchy process, and the failure possibility of the third-party to urban gas pipeline was calculated. Taking gas pipelines of a certain large provincial capital city as an example, the risk assessment structure of the method was proved to conform to the actual situation, which provides the basis for the safety risk prevention.

  6. Pressure Ulcer Risk Evaluation in Critical Patients: Clinical and Social Characteristics.

    PubMed

    de Azevedo Macena, Mônica Suêla; da Costa Silva, Rayanne Suely; Dias Fernandes, Maria Isabel Da Conceição; de Almeida Medeiros, Ana Beatriz; Batista Lúcio, Kadyjina Daiane; de Carvalho Lira, Ana Luisa Brandão

    2017-01-01

    Pressure ulcers increase hospital stays and treatment costs due to their complications. Therefore, recognizing factors that contribute to pressure ulcer risk are important to patient safety. To evaluate the association between the scores of the Waterlow, Braden, and Norton scales and clinical and social characteristics in critically ill patients. A cross-sectional study of 78 patients in an adult intensive care unit of a university hospital in Northeastern Brazil was conducted from July to December 2015. Data included social and clinical information and the risk factors of the Braden, Norton and Waterlow scales. Data were analysed by the descriptive and inferential statistics. Most of the participants were female, adults and elderly people with brown skin colour, low education levels and insufficient income. Most of them showed a high risk for developing pressure ulcers using the three evaluated scales. Age, smoking status, diabetes and hypertension were associated with scores on the Waterlow, Braden and Norton scales. Age, use of the tobacco, diabetes and hypertension were associated with the risk of pressure ulcers in ICU patients.

  7. Failure Analysis and Magnetic Evaluation of Tertiary Superheater Tube Used in Gas-Fired Boiler

    NASA Astrophysics Data System (ADS)

    Mohapatra, J. N.; Patil, Sujay; Sah, Rameshwar; Krishna, P. C.; Eswarappa, B.

    2018-02-01

    Failure analysis was carried out on a prematurely failed tertiary superheater tube used in gas-fired boiler. The analysis includes a comparative study of visual examination, chemical composition, hardness and microstructure at failed region, adjacent and far to failure as well as on fresh tube. The chemistry was found matching to the standard specification, whereas the hardness was low in failed tube compared to the fish mouth opening region and the fresh tube. Microscopic examination of failed sample revealed the presence of spheroidal carbides of Cr and Mo predominantly along the grain boundaries. The primary cause of failure is found to be localized heating. Magnetic hysteresis loop (MHL) measurements were carried out to correlate the magnetic parameters with microstructure and mechanical properties to establish a possible non-destructive evaluation (NDE) for health monitoring of the tubes. The coercivity of the MHL showed a very good correlation with microstructure and mechanical properties deterioration enabling a possible NDE technique for the health monitoring of the tubes.

  8. Evaluating selection and efficacy of pressure-relieving equipment.

    PubMed

    Chaloner, Donna; Stevens, Jenny

    2003-06-01

    The drive towards evidence-based practice has highlighted the lack of randomized controlled trials that compare interventions such as pressure-relieving medical devices. This may influence practitioners, particularly purchasing practitioners, to consider other types of evidence when appraising literature to determine clinical practice and support recommendations and local guidelines. This article will illustrate the development of an audit tool used to evaluate nurses' knowledge and skills in patient assessment, selection and installation of appropriate pressure-relieving equipment. The tool also assists in assessing clinical effectiveness and user satisfaction of equipment. This article focuses on a small audit of the Karomed Ltd Transair 1500 (also known as the 3-Comm) mattress replacement system.

  9. Prospective clinical study to evaluate an oscillometric blood pressure monitor in pet rabbits.

    PubMed

    Bellini, Luca; Veladiano, Irene A; Schrank, Magdalena; Candaten, Matteo; Mollo, Antonio

    2018-02-27

    Rabbits are particularly sensitive to develop hypotension during sedation or anaesthesia. Values of systolic or mean non-invasive arterial blood pressure below 80 or 60 mmHg respectively are common under anaesthesia despite an ongoing surgery. A reliable method of monitoring arterial blood pressure is extremely important, although invasive technique is not always possible due to the anatomy and dimension of the artery. The aim of this study was to evaluate the agreement between a new oscillometric device for non-invasive arterial blood pressure measurement and the invasive method. Moreover the trending ability of the device, ability to identify changes in the same direction with the invasive methods, was evaluated as well as the sensibility of the device in identifying hypotension arbitrarily defined as invasive arterial blood pressure below 80 or 60 mmHg. Bland-Altman analysis for repeated measurements showed a poor agreement between the two methods; the oscillometric device overestimated the invasive arterial blood pressure, particularly at high arterial pressure values. The same analysis repeated considering oscillometric measurement that match invasive mean pressure lower or equal to 60 mmHg showed a decrease in biases and limits of agreement between methods. The trending ability of the device, evaluated with both the 4-quadrant plot and the polar plot was poor. Concordance rate of mean arterial blood pressure was higher than systolic and diastolic pressure although inferior to 90%. The sensibility of the device in detecting hypotension defined as systolic or mean invasive arterial blood pressure lower than 80 or 60 mmHg was superior for mean oscillometric pressure rather than systolic. A sensitivity of 92% was achieved with an oscillometric measurement for mean pressure below 65 mmHg instead of 60 mmHg. Non-invasive systolic blood pressure is less sensitive as indicator of hypotension regardless of the cutoff limit considered. Although mean invasive

  10. Field Evaluation of Ultra-High Pressure Water Systems for Runway Rubber Removal

    DTIC Science & Technology

    2014-04-01

    ER D C/ G SL T R- 14 -1 1 Field Evaluation of Ultra-High Pressure Water Systems for Runway Rubber Removal G eo te ch ni ca l a nd S tr...Field Evaluation of Ultra-High Pressure Water Systems for Runway Rubber Removal Aaron B. Pullen Applied Research Associates, Inc. 421 Oak Avenue...collaboration with Applied Research Associates, Inc. (ARA). Several types of commercial UHPW water blasting systems were tested on an ungrooved portland cement

  11. Mineralocorticoid Receptor Activation Contributes to the Supine Hypertension of Autonomic Failure.

    PubMed

    Arnold, Amy C; Okamoto, Luis E; Gamboa, Alfredo; Black, Bonnie K; Raj, Satish R; Elijovich, Fernando; Robertson, David; Shibao, Cyndya A; Biaggioni, Italo

    2016-02-01

    Primary autonomic failure is characterized by disabling orthostatic hypotension, but at least half of these patients have paradoxical supine hypertension. Renin-angiotensin mechanisms were not initially thought to contribute to this hypertension because plasma renin activity is often undetectable in autonomic failure. Plasma aldosterone levels are normal, however, and we recently showed that plasma angiotensin II is elevated and acts at AT1 (angiotensin type 1) receptors to contribute to hypertension in these patients. Because aldosterone and angiotensin II can also bind mineralocorticoid receptors to elevate blood pressure, we hypothesized that mineralocorticoid receptor activation plays a role in the hypertension of autonomic failure. To test this hypothesis, we determined the acute effects of the mineralocorticoid receptor antagonist eplerenone (50 mg, oral) versus placebo on supine blood pressure in a randomized, double-blind, crossover study. Medications were given at 8:00 pm with blood pressure recorded every 2 hours for 12 hours. Ten primary autonomic failure patients with supine hypertension completed this study (7 pure autonomic failure, 2 multiple system atrophy, 1 parkinson's disease; 7 male; 70±2 years of age). Eplerenone maximally reduced supine systolic blood pressure by 32±6 mm Hg at 8 hours after administration (versus 8±10 mm Hg placebo, P=0.016), with no effect on nocturia (12-hour urine volume: 985±134 mL placebo versus 931±94 mL eplerenone, P=0.492; nocturnal weight loss: -1.19±0.15 kg placebo versus -1.18±0.15 kg eplerenone, P=0.766). These findings suggest that inappropriate mineralocorticoid receptor activation contributes to the hypertension of autonomic failure, likely independent of canonical mineralocorticoid effects, and provides rationale for use of eplerenone in these patients. © 2015 American Heart Association, Inc.

  12. Evaluation of the accuracy of the Rotating Parallel Ray Omnidirectional Integration for instantaneous pressure reconstruction from the measured pressure gradient

    NASA Astrophysics Data System (ADS)

    Moreto, Jose; Liu, Xiaofeng

    2017-11-01

    The accuracy of the Rotating Parallel Ray omnidirectional integration for pressure reconstruction from the measured pressure gradient (Liu et al., AIAA paper 2016-1049) is evaluated against both the Circular Virtual Boundary omnidirectional integration (Liu and Katz, 2006 and 2013) and the conventional Poisson equation approach. Dirichlet condition at one boundary point and Neumann condition at all other boundary points are applied to the Poisson solver. A direct numerical simulation database of isotropic turbulence flow (JHTDB), with a homogeneously distributed random noise added to the entire field of DNS pressure gradient, is used to assess the performance of the methods. The random noise, generated by the Matlab function Rand, has a magnitude varying randomly within the range of +/-40% of the maximum DNS pressure gradient. To account for the effect of the noise distribution pattern on the reconstructed pressure accuracy, a total of 1000 different noise distributions achieved by using different random number seeds are involved in the evaluation. Final results after averaging the 1000 realizations show that the error of the reconstructed pressure normalized by the DNS pressure variation range is 0.15 +/-0.07 for the Poisson equation approach, 0.028 +/-0.003 for the Circular Virtual Boundary method and 0.027 +/-0.003 for the Rotating Parallel Ray method, indicating the robustness of the Rotating Parallel Ray method in pressure reconstruction. Sponsor: The San Diego State University UGP program.

  13. Evaluation of failure criterion for graphite/epoxy fabric laminates

    NASA Technical Reports Server (NTRS)

    Tennyson, R. C.; Wharram, G. E.

    1985-01-01

    The development and application of the tensor polynomial failure criterion for composite laminate analysis is described. Emphasis is given to the fabrication and testing of Narmco Rigidite 5208-WT300, a plain weave fabric of Thornel 300 Graphite fibers impregnated with Narmco 5208 Resin. The quadratic-failure criterion with F sub 12=0 provides accurate estimates of failure stresses for the graphite/epoxy investigated. The cubic failure criterion was recast into an operationally easier form, providing design curves that can be applied to laminates fabricated from orthotropic woven fabric prepregs. In the form presented, no interaction strength tests are required, although recourse to the quadratic model and the principal strength parameters is necessary. However, insufficient test data exist at present to generalize this approach for all prepreg constructions, and its use must be restricted to the generic materials and configurations investigated to date.

  14. Effects of pressure angle and tip relief on the life of speed increasing gearbox: a case study.

    PubMed

    Shanmugasundaram, Sankar; Kumaresan, Manivarma; Muthusamy, Nataraj

    2014-01-01

    This paper examines failure of helical gear in speed increasing gearbox used in the wind turbine generator (WTG). In addition, an attempt has been made to get suitable gear micro-geometry such as pressure angle and tip relief to minimize the gear failure in the wind turbines. As the gear trains in the wind turbine gearbox is prearranged with higher speed ratio and the gearboxes experience shock load due to atmospheric turbulence, gust wind speed, non-synchronization of pitching, frequent grid drops and failure of braking, the gear failure occurs either in the intermediate or high speed stage pinion. KISS soft gear calculation software was used to determine the gear specifications and analysis is carried out in ANSYS software version.11.0 for the existing and the proposed gear to evaluate the performance of bending stress tooth deflection and stiffness. The main objective of this research study is to propose suitable gear micro-geometry that is tip relief and pressure angle blend for increasing tooth strength of the helical gear used in the wind turbine for trouble free operation.

  15. Analytical Method to Evaluate Failure Potential During High-Risk Component Development

    NASA Technical Reports Server (NTRS)

    Tumer, Irem Y.; Stone, Robert B.; Clancy, Daniel (Technical Monitor)

    2001-01-01

    Communicating failure mode information during design and manufacturing is a crucial task for failure prevention. Most processes use Failure Modes and Effects types of analyses, as well as prior knowledge and experience, to determine the potential modes of failures a product might encounter during its lifetime. When new products are being considered and designed, this knowledge and information is expanded upon to help designers extrapolate based on their similarity with existing products and the potential design tradeoffs. This paper makes use of similarities and tradeoffs that exist between different failure modes based on the functionality of each component/product. In this light, a function-failure method is developed to help the design of new products with solutions for functions that eliminate or reduce the potential of a failure mode. The method is applied to a simplified rotating machinery example in this paper, and is proposed as a means to account for helicopter failure modes during design and production, addressing stringent safety and performance requirements for NASA applications.

  16. SU-F-T-246: Evaluation of Healthcare Failure Mode And Effect Analysis For Risk Assessment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Harry, T; University of California, San Diego, La Jolla, CA; Manger, R

    Purpose: To evaluate the differences between the Veteran Affairs Healthcare Failure Modes and Effect Analysis (HFMEA) and the AAPM Task Group 100 Failure and Effect Analysis (FMEA) risk assessment techniques in the setting of a stereotactic radiosurgery (SRS) procedure were compared respectively. Understanding the differences in the techniques methodologies and outcomes will provide further insight into the applicability and utility of risk assessments exercises in radiation therapy. Methods: HFMEA risk assessment analysis was performed on a stereotactic radiosurgery procedure. A previous study from our institution completed a FMEA of our SRS procedure and the process map generated from this workmore » was used for the HFMEA. The process of performing the HFMEA scoring was analyzed, and the results from both analyses were compared. Results: The key differences between the two risk assessments are the scoring criteria for failure modes and identifying critical failure modes for potential hazards. The general consensus among the team performing the analyses was that scoring for the HFMEA was simpler and more intuitive then the FMEA. The FMEA identified 25 critical failure modes while the HFMEA identified 39. Seven of the FMEA critical failure modes were not identified by the HFMEA and 21 of the HFMEA critical failure modes were not identified by the FMEA. HFMEA as described by the Veteran Affairs provides guidelines on which failure modes to address first. Conclusion: HFMEA is a more efficient model for identifying gross risks in a process than FMEA. Clinics with minimal staff, time and resources can benefit from this type of risk assessment to eliminate or mitigate high risk hazards with nominal effort. FMEA can provide more in depth details but at the cost of elevated effort.« less

  17. Multimodal brain monitoring in fulminant hepatic failure

    PubMed Central

    Paschoal Jr, Fernando Mendes; Nogueira, Ricardo Carvalho; Ronconi, Karla De Almeida Lins; de Lima Oliveira, Marcelo; Teixeira, Manoel Jacobsen; Bor-Seng-Shu, Edson

    2016-01-01

    Acute liver failure, also known as fulminant hepatic failure (FHF), embraces a spectrum of clinical entities characterized by acute liver injury, severe hepatocellular dysfunction, and hepatic encephalopathy. Cerebral edema and intracranial hypertension are common causes of mortality in patients with FHF. The management of patients who present acute liver failure starts with determining the cause and an initial evaluation of prognosis. Regardless of whether or not patients are listed for liver transplantation, they should still be monitored for recovery, death, or transplantation. In the past, neuromonitoring was restricted to serial clinical neurologic examination and, in some cases, intracranial pressure monitoring. Over the years, this monitoring has proven insufficient, as brain abnormalities were detected at late and irreversible stages. The need for real-time monitoring of brain functions to favor prompt treatment and avert irreversible brain injuries led to the concepts of multimodal monitoring and neurophysiological decision support. New monitoring techniques, such as brain tissue oxygen tension, continuous electroencephalogram, transcranial Doppler, and cerebral microdialysis, have been developed. These techniques enable early diagnosis of brain hemodynamic, electrical, and biochemical changes, allow brain anatomical and physiological monitoring-guided therapy, and have improved patient survival rates. The purpose of this review is to discuss the multimodality methods available for monitoring patients with FHF in the neurocritical care setting. PMID:27574545

  18. Pore fluid pressure and the seismic cycle

    NASA Astrophysics Data System (ADS)

    French, M. E.; Zhu, W.; Hirth, G.; Belzer, B.

    2017-12-01

    In the brittle crust, the critical shear stress required for fault slip decreases with increasing pore fluid pressures according to the effective stress criterion. As a result, higher pore fluid pressures are thought to promote fault slip and seismogenesis, consistent with observations that increasing fluid pressure as a result of wastewater injection is correlated with increased seismicity. On the other hand, elevated pore fluid pressure is also proposed to promote slow stable failure rather than seismicity along some fault zones, including during slow slip in subduction zones. Here we review recent experimental evidence for the roles that pore fluid pressure and the effective stress play in controlling fault slip behavior. Using two sets of experiments on serpentine fault gouge, we show that increasing fluid pressure does decrease the shear stress for reactivation under brittle conditions. However, under semi-brittle conditions as expected near the base of the seismogenic zone, high pore fluid pressures are much less effective at reducing the shear stress of reactivation even though deformation is localized and frictional. We use an additional study on serpentinite to show that cohesive fault rocks, potentially the product of healing and cementation, experience an increase in fracture energy during faulting as fluid pressures approach lithostatic, which can lead to more stable failure. Structural observations show that the increased fracture energy is associated with a greater intensity of transgranular fracturing and delocalization of deformation. Experiments on several lithologies indicate that the stabilizing effect of fluid pressure occurs independent of rock composition and hydraulic properties. Thus, high pore fluid pressures have the potential to either enhance seismicity or promote stable faulting depending on pressure, temperature, and fluid pressure conditions. Together, the results of these studies indicate that pore fluid pressure promotes

  19. Pore pressure control on faulting behavior in a block-gouge system

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Juanes, R.

    2016-12-01

    Pore fluid pressure in a fault zone can be altered by natural processes (e.g., mineral dehydration and thermal pressurization) and industrial operations involving subsurface fluid injection/extraction for the development of energy and water resources. However, the effect of pore pressure change on the stability and slip motion of a preexisting geologic fault remain poorly understood; yet they are critical for the assessment of seismic risk. In this work, we develop a micromechanical model to investigate the effect of pore pressure on faulting behavior. The model couples pore network fluid flow and mechanics of the solid grains. We conceptualize the fault zone as a gouge layer sandwiched between two blocks; the block material is represented by a group of contact-bonded grains and the gouge is composed of unbonded grains. A pore network is extracted from the particulate pack of the block-gouge system with pore body volumes and pore throat conductivities calculated rigorously based on the geometry of the local pore space. Pore fluid exerts pressure force onto the grains, the motion of which is solved using the discrete element method (DEM). The model updates the pore network regularly in response to deformation of the solid matrix. We study the fault stability in the presence of a pressure inhomogeneity (gradient) across the gouge layer, and compare it with the case of homogeneous pore pressure. We consider both normal and thrust faulting scenarios with a focus on the onset of shear failure along the block-gouge interfaces. Numerical simulations show that the slip behavior is characterized by intermittent dynamics, which is evident in the number of slipping contacts at the block-gouge interfaces and the total kinetic energy of the gouge particles. Numerical results also show that, for the case of pressure inhomogeneity, the onset of slip occurs earlier for the side with higher pressure, and that this onset appears to be controlled by the maximum pressure of both sides

  20. Application of Quality Management Tools for Evaluating the Failure Frequency of Cutter-Loader and Plough Mining Systems

    NASA Astrophysics Data System (ADS)

    Biały, Witold

    2017-06-01

    Failure frequency in the mining process, with a focus on the mining machine, has been presented and illustrated by the example of two coal-mines. Two mining systems have been subjected to analysis: a cutter-loader and a plough system. In order to reduce costs generated by failures, maintenance teams should regularly make sure that the machines are used and operated in a rational and effective way. Such activities will allow downtimes to be reduced, and, in consequence, will increase the effectiveness of a mining plant. The evaluation of mining machines' failure frequency contained in this study has been based on one of the traditional quality management tools - the Pareto chart.

  1. In-Situ Nondestructive Evaluation of Kevlar(Registered Trademark)and Carbon Fiber Reinforced Composite Micromechanics for Improved Composite Overwrapped Pressure Vessel Health Monitoring

    NASA Technical Reports Server (NTRS)

    Waller, Jess; Saulsberry, Regor

    2012-01-01

    NASA has been faced with recertification and life extension issues for epoxy-impregnated Kevlar 49 (K/Ep) and carbon (C/Ep) composite overwrapped pressure vessels (COPVs) used in various systems on the Space Shuttle and International Space Station, respectively. Each COPV has varying criticality, damage and repair histories, time at pressure, and pressure cycles. COPVs are of particular concern due to the insidious and catastrophic burst-before-leak failure mode caused by stress rupture (SR) of the composite overwrap. SR life has been defined [1] as the minimum time during which the composite maintains structural integrity considering the combined effects of stress level(s), time at stress level(s), and associated environment. SR has none of the features of predictability associated with metal pressure vessels, such as crack geometry, growth rate and size, or other features that lend themselves to nondestructive evaluation (NDE). In essence, the variability or surprise factor associated with SR cannot be eliminated. C/Ep COPVs are also susceptible to impact damage that can lead to reduced burst pressure even when the amount of damage to the COPV is below the visual detection threshold [2], thus necessitating implementation of a mechanical damage control plan [1]. Last, COPVs can also fail prematurely due to material or design noncompliance. In each case (SR, impact or noncompliance), out-of-family behavior is expected leading to a higher probability of failure at a given stress, hence, greater uncertainty in performance. For these reasons, NASA has been actively engaged in research to develop NDE methods that can be used during post-manufacture qualification, in-service inspection, and in-situ structural health monitoring. Acoustic emission (AE) is one of the more promising NDE techniques for detecting and monitoring, in real-time, the strain energy release and corresponding stress-wave propagation produced by actively growing flaws and defects in composite

  2. Failure Behavior of Elbows with Local Wall Thinning

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Ho; Lee, Jeong-Keun; Park, Jai-Hak

    Wall thinning defect due to corrosion is one of major aging phenomena in carbon steel pipes in most plant industries, and it results in reducing load carrying capacity of the piping components. A failure test system was set up for real scale elbows containing various simulated wall thinning defects, and monotonic in-plane bending tests were performed under internal pressure to find out the failure behavior of them. The failure behavior of wall-thinned elbows was characterized by the circumferential angle of thinned region and the loading conditions to the piping system.

  3. Hypercalcemia with renal failure.

    PubMed

    Bhavani, Nisha; Praveen, Valiyaparambil Pavithran; Jayakumar, Rohinivilasam Vasukutty; Nair, Vasantha; Muraleedharan, Mangath; Kuma, Harish; Unnikrishnan, Ambika Gopalakrishnan; Menon, Vadayath Usha

    2012-06-01

    We report a cse of nephrocalcinosis with renal failure which on evaluation was found to have hypercalcemia. Further investigations showed an inappropriately normal intact parathormone (iPTH) and 1,25 dihydroxy-vitamin D level in the setting of renal failure. Probing for a cause of non-PTH mediated hypercalcemia led to the diagnosis of sarcoidosis. Treatment with glucocorticoids could partially reverse the renal failure and control the hypercalcemia. This case illustrates the importance of careful interpretation of laboratory parameters especially levels of iPTH and vitamin D metabolites in renal failure.

  4. Evaluation of an electric bed frame and pressure-reducing mattresses.

    PubMed

    Gray, D; Whelan, S; Russell, G; Balura, N

    2000-12-01

    Pressure ulcers remain a challenge to all healthcare professionals. With the trend towards caring for ill patients in the community there is a need to ensure that equipment used to prevent pressure ulcers in these patients is effective. It is not always appropriate to simply use equipment designed for hospital. This article describes the evaluation of an electric bed frame and three mattresses specifically designed for patients in the community, in either their own homes or nursing home/residential care. The location of this research can reduce the number of participants recruited. In order to compensate for this, three different methods of evaluation were employed - clinical, laboratory and anecdotal - which have produced results relevant to both purchasers and users of the system tested.

  5. Evaluation of atomic pressure in the multiple time-step integration algorithm.

    PubMed

    Andoh, Yoshimichi; Yoshii, Noriyuki; Yamada, Atsushi; Okazaki, Susumu

    2017-04-15

    In molecular dynamics (MD) calculations, reduction in calculation time per MD loop is essential. A multiple time-step (MTS) integration algorithm, the RESPA (Tuckerman and Berne, J. Chem. Phys. 1992, 97, 1990-2001), enables reductions in calculation time by decreasing the frequency of time-consuming long-range interaction calculations. However, the RESPA MTS algorithm involves uncertainties in evaluating the atomic interaction-based pressure (i.e., atomic pressure) of systems with and without holonomic constraints. It is not clear which intermediate forces and constraint forces in the MTS integration procedure should be used to calculate the atomic pressure. In this article, we propose a series of equations to evaluate the atomic pressure in the RESPA MTS integration procedure on the basis of its equivalence to the Velocity-Verlet integration procedure with a single time step (STS). The equations guarantee time-reversibility even for the system with holonomic constrants. Furthermore, we generalize the equations to both (i) arbitrary number of inner time steps and (ii) arbitrary number of force components (RESPA levels). The atomic pressure calculated by our equations with the MTS integration shows excellent agreement with the reference value with the STS, whereas pressures calculated using the conventional ad hoc equations deviated from it. Our equations can be extended straightforwardly to the MTS integration algorithm for the isothermal NVT and isothermal-isobaric NPT ensembles. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  6. Failure Investigation of an Intra-Manifold Explosion in a Horizontally-Mounted 870 lbf Reaction Control Thruster

    NASA Technical Reports Server (NTRS)

    Durning, Joseph G., III; Westover, Shayne C.; Cone, Darren M.

    2011-01-01

    In June 2010, an 870 lbf Space Shuttle Orbiter Reaction Control System Primary Thruster experienced an unintended shutdown during a test being performed at the NASA White Sands Test Facility. Subsequent removal and inspection of the thruster revealed permanent deformation and misalignment of the thruster valve mounting plate. Destructive evaluation determined that after three nominal firing sequences, the thruster had experienced an energetic event within the fuel (monomethylhydrazine) manifold at the start of the fourth firing sequence. The current understanding of the phenomenon of intra-manifold explosions in hypergolic bipropellant thrusters is documented in literature where it is colloquially referred to as a ZOT. The typical ZOT scenario involves operation of a thruster in a gravitational field with environmental pressures above the triple point pressure of the propellants. Post-firing, when the thruster valves are commanded closed, there remains a residual quantity of propellant in both the fuel and oxidizer (nitrogen tetroxide) injector manifolds known as the "dribble volume". In an ambient ground test configuration, these propellant volumes will drain from the injector manifolds but are impeded by the local atmospheric pressure. The evacuation of propellants from the thruster injector manifolds relies on the fluids vapor pressure to expel the liquid. The higher vapor pressure oxidizer will evacuate from the manifold before the lower vapor pressure fuel. The localized cooling resulting from the oxidizer boiling during manifold draining can result in fuel vapor migration and condensation in the oxidizer passage. The liquid fuel will then react with the oxidizer that enters the manifold during the next firing and may produce a localized high pressure reaction or explosion within the confines of the oxidizer injector manifold. The typical ZOT scenario was considered during this failure investigation, but was ultimately ruled out as a cause of the explosion

  7. Postural effects on intracranial pressure: modeling and clinical evaluation.

    PubMed

    Qvarlander, Sara; Sundström, Nina; Malm, Jan; Eklund, Anders

    2013-11-01

    The physiological effect of posture on intracranial pressure (ICP) is not well described. This study defined and evaluated three mathematical models describing the postural effects on ICP, designed to predict ICP at different head-up tilt angles from the supine ICP value. Model I was based on a hydrostatic indifference point for the cerebrospinal fluid (CSF) system, i.e., the existence of a point in the system where pressure is independent of body position. Models II and III were based on Davson's equation for CSF absorption, which relates ICP to venous pressure, and postulated that gravitational effects within the venous system are transferred to the CSF system. Model II assumed a fully communicating venous system, and model III assumed that collapse of the jugular veins at higher tilt angles creates two separate hydrostatic compartments. Evaluation of the models was based on ICP measurements at seven tilt angles (0-71°) in 27 normal pressure hydrocephalus patients. ICP decreased with tilt angle (ANOVA: P < 0.01). The reduction was well predicted by model III (ANOVA lack-of-fit: P = 0.65), which showed excellent fit against measured ICP. Neither model I nor II adequately described the reduction in ICP (ANOVA lack-of-fit: P < 0.01). Postural changes in ICP could not be predicted based on the currently accepted theory of a hydrostatic indifference point for the CSF system, but a new model combining Davson's equation for CSF absorption and hydrostatic gradients in a collapsible venous system performed well and can be useful in future research on gravity and CSF physiology.

  8. Preoperative short hookwire placement for small pulmonary lesions: evaluation of technical success and risk factors for initial placement failure.

    PubMed

    Iguchi, Toshihiro; Hiraki, Takao; Matsui, Yusuke; Fujiwara, Hiroyasu; Masaoka, Yoshihisa; Tanaka, Takashi; Sato, Takuya; Gobara, Hideo; Toyooka, Shinichi; Kanazawa, Susumu

    2018-05-01

    To retrospectively evaluate the technical success of computed tomography fluoroscopy-guided short hookwire placement before video-assisted thoracoscopic surgery and to identify the risk factors for initial placement failure. In total, 401 short hookwire placements for 401 lesions (mean diameter 9.3 mm) were reviewed. Technical success was defined as correct positioning of the hookwire. Possible risk factors for initial placement failure (i.e., requirement for placement of an additional hookwire or to abort the attempt) were evaluated using logistic regression analysis for all procedures, and for procedures performed via the conventional route separately. Of the 401 initial placements, 383 were successful and 18 failed. Short hookwires were finally placed for 399 of 401 lesions (99.5%). Univariate logistic regression analyses revealed that in all 401 procedures only the transfissural approach was a significant independent predictor of initial placement failure (odds ratio, OR, 15.326; 95% confidence interval, CI, 5.429-43.267; p < 0.001) and for the 374 procedures performed via the conventional route only lesion size was a significant independent predictor of failure (OR 0.793, 95% CI 0.631-0.996; p = 0.046). The technical success of preoperative short hookwire placement was extremely high. The transfissural approach was a predictor initial placement failure for all procedures and small lesion size was a predictor of initial placement failure for procedures performed via the conventional route. • Technical success of preoperative short hookwire placement was extremely high. • The transfissural approach was a significant independent predictor of initial placement failure for all procedures. • Small lesion size was a significant independent predictor of initial placement failure for procedures performed via the conventional route.

  9. Study on Failure of Third-Party Damage for Urban Gas Pipeline Based on Fuzzy Comprehensive Evaluation

    PubMed Central

    Li, Jun; Zhang, Hong; Han, Yinshan; Wang, Baodong

    2016-01-01

    Focusing on the diversity, complexity and uncertainty of the third-party damage accident, the failure probability of third-party damage to urban gas pipeline was evaluated on the theory of analytic hierarchy process and fuzzy mathematics. The fault tree of third-party damage containing 56 basic events was built by hazard identification of third-party damage. The fuzzy evaluation of basic event probabilities were conducted by the expert judgment method and using membership function of fuzzy set. The determination of the weight of each expert and the modification of the evaluation opinions were accomplished using the improved analytic hierarchy process, and the failure possibility of the third-party to urban gas pipeline was calculated. Taking gas pipelines of a certain large provincial capital city as an example, the risk assessment structure of the method was proved to conform to the actual situation, which provides the basis for the safety risk prevention. PMID:27875545

  10. Choline Diet and Its Gut Microbe Derived Metabolite, Trimethylamine N-Oxide (TMAO), Exacerbate Pressure Overload-Induced Heart Failure

    PubMed Central

    Organ, Chelsea L.; Otsuka, Hiroyuki; Bhushan, Shashi; Wang, Zeneng; Bradley, Jessica; Trivedi, Rishi; Polhemus, David J.; Tang, W. H. Wilson; Wu, Yuping; Hazen, Stanley L.; Lefer, David J.

    2015-01-01

    Background Trimethylamine N-oxide (TMAO), a gut microbe dependent metabolite of dietary choline and other trimethylamine containing nutrients, is both elevated in the circulation of patients suffering from heart failure (HF) and heralds worse overall prognosis. In animal studies, dietary choline or TMAO significantly accelerate atherosclerotic lesion development in ApoE deficient mice, and reduction in TMAO levels inhibits atherosclerosis development in the LDL receptor knockout mouse. Methods and Results C57BL6/J mice were fed either a control diet, a diet containing choline (1.2%) or a diet containing TMAO (0.12%) starting 3 weeks prior to surgical TAC. Mice were studied for 12 weeks following TAC. Cardiac function and left ventricular structure were monitored at 3-week intervals using echocardiography. Twelve weeks post-TAC myocardial tissues were collected to evaluate cardiac and vascular fibrosis, and blood samples were evaluated for cardiac BNP, choline, and TMAO levels. Pulmonary edema, cardiac enlargement, and left ventricular ejection fraction (LVEF) were significantly (p < 0.05, each) worse in mice fed either TMAO or choline supplemented diets compared to the control diet. In addition, myocardial fibrosis was also significantly greater (p < 0.01, each) in the TMAO and choline groups relative to controls. Conclusions Heart failure severity is significantly enhanced in mice fed diets supplemented in either choline or the gut microbe-dependent metabolite TMAO. The present results suggest that further studies are warranted examining whether gut microbiota and the dietary choline -> TMAO pathway contribute to increased heart failure susceptibility. PMID:26699388

  11. Diuretics as pathogenetic treatment for heart failure

    PubMed Central

    Guglin, Maya

    2011-01-01

    Increased intracardiac filling pressure or congestion causes symptoms and leads to hospital admissions in patients with heart failure, regardless of their systolic function. A history of hospital admission, in turn, predicts further hospitalizations and morbidity, and a higher number of hospitalizations determine higher mortality. Congestion is therefore the driving force of the natural history of heart failure. Congestion is the syndrome shared by heart failure with preserved and reduced systolic function. These two conditions have almost identical morbidity, mortality, and survival because the outcomes are driven by congestion. A small difference in favor of heart failure with preserved systolic function comes from decreased ejection fraction and left ventricular remodeling which is only present in heart failure with decreased systolic function. The magnitude of this difference reflects the contribution of decreased systolic function and ventricular remodeling to the progression of heart failure. The only treatment available for congestion is fluid removal via diuretics, ultrafiltration, or dialysis. It is the only treatment that works equally well for heart failure with reduced and preserved systolic function because it affects congestion, the main pathogenetic feature of the disease. Diuretics are pathogenetic therapy for heart failure. PMID:21403798

  12. Tools for Economic Analysis of Patient Management Interventions in Heart Failure Cost-Effectiveness Model: A Web-based program designed to evaluate the cost-effectiveness of disease management programs in heart failure.

    PubMed

    Reed, Shelby D; Neilson, Matthew P; Gardner, Matthew; Li, Yanhong; Briggs, Andrew H; Polsky, Daniel E; Graham, Felicia L; Bowers, Margaret T; Paul, Sara C; Granger, Bradi B; Schulman, Kevin A; Whellan, David J; Riegel, Barbara; Levy, Wayne C

    2015-11-01

    Heart failure disease management programs can influence medical resource use and quality-adjusted survival. Because projecting long-term costs and survival is challenging, a consistent and valid approach to extrapolating short-term outcomes would be valuable. We developed the Tools for Economic Analysis of Patient Management Interventions in Heart Failure Cost-Effectiveness Model, a Web-based simulation tool designed to integrate data on demographic, clinical, and laboratory characteristics; use of evidence-based medications; and costs to generate predicted outcomes. Survival projections are based on a modified Seattle Heart Failure Model. Projections of resource use and quality of life are modeled using relationships with time-varying Seattle Heart Failure Model scores. The model can be used to evaluate parallel-group and single-cohort study designs and hypothetical programs. Simulations consist of 10,000 pairs of virtual cohorts used to generate estimates of resource use, costs, survival, and incremental cost-effectiveness ratios from user inputs. The model demonstrated acceptable internal and external validity in replicating resource use, costs, and survival estimates from 3 clinical trials. Simulations to evaluate the cost-effectiveness of heart failure disease management programs across 3 scenarios demonstrate how the model can be used to design a program in which short-term improvements in functioning and use of evidence-based treatments are sufficient to demonstrate good long-term value to the health care system. The Tools for Economic Analysis of Patient Management Interventions in Heart Failure Cost-Effectiveness Model provides researchers and providers with a tool for conducting long-term cost-effectiveness analyses of disease management programs in heart failure. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Developmental problems and their solution for the Space Shuttle main engine alternate liquid oxygen high-pressure turbopump: Anomaly or failure investigation the key

    NASA Astrophysics Data System (ADS)

    Ryan, R.; Gross, L. A.

    1995-05-01

    The Space Shuttle main engine (SSME) alternate high-pressure liquid oxygen pump experienced synchronous vibration and ball bearing life problems that were program threatening. The success of the program hinged on the ability to solve these development problems. The design and solutions to these problems are engirded in the lessons learned and experiences from prior programs, technology programs, and the ability to properly conduct failure or anomaly investigations. The failure investigation determines the problem cause and is the basis for recommending design solutions. For a complex problem, a comprehensive solution requires that formal investigation procedures be used, including fault trees, resolution logic, and action items worked through a concurrent engineering-multidiscipline team. The normal tendency to use an intuitive, cut-and-try approach will usually prove to be costly, both in money and time and will reach a less than optimum, poorly understood answer. The SSME alternate high-pressure oxidizer turbopump development has had two complex problems critical to program success: (1) high synchronous vibrations and (2) excessive ball bearing wear. This paper will use these two problems as examples of this formal failure investigation approach. The results of the team's investigation provides insight into the complexity of the turbomachinery technical discipline interacting/sensitivities and the fine balance of competing investigations required to solve problems and guarantee program success. It is very important to the solution process that maximum use be made of the resources that both the contractor and Government can bring to the problem in a supporting and noncompeting way. There is no place for the not-invented-here attitude. The resources include, but are not limited to: (1) specially skilled professionals; (2) supporting technologies; (3) computational codes and capabilities; and (4) test and manufacturing facilities.

  14. Developmental problems and their solution for the Space Shuttle main engine alternate liquid oxygen high-pressure turbopump: Anomaly or failure investigation the key

    NASA Technical Reports Server (NTRS)

    Ryan, R.; Gross, L. A.

    1995-01-01

    The Space Shuttle main engine (SSME) alternate high-pressure liquid oxygen pump experienced synchronous vibration and ball bearing life problems that were program threatening. The success of the program hinged on the ability to solve these development problems. The design and solutions to these problems are engirded in the lessons learned and experiences from prior programs, technology programs, and the ability to properly conduct failure or anomaly investigations. The failure investigation determines the problem cause and is the basis for recommending design solutions. For a complex problem, a comprehensive solution requires that formal investigation procedures be used, including fault trees, resolution logic, and action items worked through a concurrent engineering-multidiscipline team. The normal tendency to use an intuitive, cut-and-try approach will usually prove to be costly, both in money and time and will reach a less than optimum, poorly understood answer. The SSME alternate high-pressure oxidizer turbopump development has had two complex problems critical to program success: (1) high synchronous vibrations and (2) excessive ball bearing wear. This paper will use these two problems as examples of this formal failure investigation approach. The results of the team's investigation provides insight into the complexity of the turbomachinery technical discipline interacting/sensitivities and the fine balance of competing investigations required to solve problems and guarantee program success. It is very important to the solution process that maximum use be made of the resources that both the contractor and Government can bring to the problem in a supporting and noncompeting way. There is no place for the not-invented-here attitude. The resources include, but are not limited to: (1) specially skilled professionals; (2) supporting technologies; (3) computational codes and capabilities; and (4) test and manufacturing facilities.

  15. Sleep Disordered Breathing in Patients with Heart Failure: Pathophysiology and Management

    PubMed Central

    Sharma, Bhavneesh; McSharry, David; Malhotra, Atul

    2013-01-01

    Opinion statement Sleep disordered breathing (SDB) is common in heart failure patients across the range of ejection fractions and is associated with adverse prognosis. Although effective pharmacologic and device-based treatment of heart failure may reduce the frequency or severity of SDB, heart failure treatment alone may not be adequate to restore normal breathing during sleep. Continuous positive airway pressure (CPAP) is the major treatment for SDB in heart failure, especially if obstructive rather than central sleep apnea (CSA) predominates. Adequate suppression of CSA by PAP is associated with a heart transplant-free survival benefit, although randomized trials are ongoing. Bilevel PAP (BPAP) may be as effective as CPAP in treating SDB and may be preferable over CPAP in patients who experience expiratory pressure discomfort. Adaptive (or auto) servo-ventilation (ASV), which adjusts the PAP depending on the patient’s airflow or tidal volume, may be useful in congestive heart failure patients if CPAP is ineffective. Other therapies that have been proposed for SDB in congestive heart failure include nocturnal oxygen, CO2 administration (by adding dead space), theophylline, and acetazolamide; most of which have not been systematically studied in outcome-based prospective randomized trials. PMID:21894522

  16. Positive end expiratory pressure in acute hypoxemic respiratory failure due to community acquired pneumonia: do we need a personalized approach?

    PubMed Central

    Paolini, Valentina; Faverio, Paola; Aliberti, Stefano; Messinesi, Grazia; Foti, Giuseppe; Sibila, Oriol; Monzani, Anna; Stainer, Anna; Pesci, Alberto

    2018-01-01

    Background Acute respiratory failure (ARF) is a life-threatening complication in patients with community acquired pneumonia (CAP). The use of non-invasive ventilation is controversial. With this prospective, observational study we aimed to describe a protocol to assess whether a patient with moderate-to-severe hypoxemic ARF secondary to CAP benefits, in clinical and laboratoristic terms, from the application of a positive end expiratory pressure (PEEP) + oxygen vs oxygen alone. Methods Patients who benefit from PEEP application (PEEP-responders) were defined as those with partial pressure of arterial oxygen to the fraction of inspired oxygen (PaO2/FiO2) increase >20% and/or reduction of respiratory distress during PEEP + oxygen therapy compared to oxygen therapy alone. Clinical characteristics and outcomes were compared between PEEP-responders and PEEP-non responders. Results Out of 41 patients, 27 (66%) benefit from PEEP application (PEEP-responders), the best response was obtained with a PEEP of 10 cmH2O in 13 patients, 7.5 cmH2O in eight and 5 cmH2O in six. PEEP-responders were less likely to present comorbidities compared to PEEP-non responders. No differences between groups were found in regards to endotracheal intubation criteria fullfillment, intensive care unit admission and in-hospital mortality, while PEEP-responders had a shorter length of hospital stay. Discussion The application of a protocol to evaluate PEEP responsiveness might be useful in patients with moderate-to-severe hypoxemic ARF due to CAP in order to personalize and maximize the effectiveness of therapy, and prevent the inappropriate PEEP use. PEEP responsiveness does not seem to be associated with better outcomes, with the exception of a shorter length of hospital stay. PMID:29404202

  17. An improved method for risk evaluation in failure modes and effects analysis of CNC lathe

    NASA Astrophysics Data System (ADS)

    Rachieru, N.; Belu, N.; Anghel, D. C.

    2015-11-01

    Failure mode and effects analysis (FMEA) is one of the most popular reliability analysis tools for identifying, assessing and eliminating potential failure modes in a wide range of industries. In general, failure modes in FMEA are evaluated and ranked through the risk priority number (RPN), which is obtained by the multiplication of crisp values of the risk factors, such as the occurrence (O), severity (S), and detection (D) of each failure mode. However, the crisp RPN method has been criticized to have several deficiencies. In this paper, linguistic variables, expressed in Gaussian, trapezoidal or triangular fuzzy numbers, are used to assess the ratings and weights for the risk factors S, O and D. A new risk assessment system based on the fuzzy set theory and fuzzy rule base theory is to be applied to assess and rank risks associated to failure modes that could appear in the functioning of Turn 55 Lathe CNC. Two case studies have been shown to demonstrate the methodology thus developed. It is illustrated a parallel between the results obtained by the traditional method and fuzzy logic for determining the RPNs. The results show that the proposed approach can reduce duplicated RPN numbers and get a more accurate, reasonable risk assessment. As a result, the stability of product and process can be assured.

  18. Evaluative threat and ambulatory blood pressure: cardiovascular effects of social stress in daily experience.

    PubMed

    Smith, Timothy W; Birmingham, Wendy; Uchino, Bert N

    2012-11-01

    Physiological effects of social evaluation are central in models of psychosocial influences on physical health. Experimental manipulations of evaluative threat evoke substantial cardiovascular and neuroendocrine responses in laboratory studies, but only preliminary evidence is available regarding naturally occurring evaluative threats in daily life. In such nonexperimental ambulatory studies, it is essential to distinguish effects of evaluative threat from related constructs known to alter stress, such as ability perceptions and concerns about appearance. 94 married, working couples (mean age 29.2 years) completed a 1-day (8 a.m. to 10 p.m.) ambulatory blood pressure protocol with random interval-contingent measurements using a Suntech monitor and Palm Pilot-based measures of control variables and momentary experiences of social-evaluative threat, concerns about appearance, and perceived ability. In hierarchical analyses for couples and multiple measurement occasions (Proc Mixed; SAS) and controlling individual differences (BMI, age, income) and potential confounds (e.g., posture, activity), higher reports of social-evaluative threat were associated with higher concurrent systolic (estimate = .87, SE = .34) and diastolic blood pressure (estimate = 1.06; SE = .26), both p < .02. Effects of social-evaluative threat remained significant when perceived ability and appearance concerns were controlled. Naturally occurring social-evaluative threat during daily activity is associated with increased systolic and diastolic blood pressure. Given associations between ambulatory blood pressure and risk of cardiovascular disease, the findings support conceptual models of threats to the social self as a potentially important influence on physical health.

  19. Role of neuropeptide Y in renal sympathetic vasoconstriction: studies in normal and congestive heart failure rats.

    PubMed

    DiBona, G F; Sawin, L L

    2001-08-01

    Sympathetic nerve activity, including that in the kidney, is increased in heart failure with increased plasma concentrations of norepinephrine and the vasoconstrictor cotransmitter neuropeptide Y (NPY). We examined the contribution of NPY to sympathetically mediated alterations in kidney function in normal and heart failure rats. Heart failure rats were created by left coronary ligation and myocardial infarction. In anesthetized normal rats, the NPY Y(1) receptor antagonist, H 409/22, at two doses, had no effect on heart rate, arterial pressure, or renal hemodynamic and excretory function. In conscious severe heart failure rats, high-dose H 409/22 decreased mean arterial pressure by 8 +/- 2 mm Hg but had no effect in normal and mild heart failure rats. During graded frequency renal sympathetic nerve stimulation (0 to 10 Hz), high-dose H 409/22 attenuated the decreases in renal blood flow only at 10 Hz (-36% +/- 5%, P <.05) in normal rats but did so at both 4 (-29% +/- 4%, P <.05) and 10 Hz (-33% +/- 5%, P <.05) in heart failure rats. The glomerular filtration rate, urinary flow rate, and sodium excretion responses to renal sympathetic nerve stimulation were not affected by high-dose H 409/22 in either normal or heart failure rats. NPY does not participate in the regulation of kidney function and arterial pressure in normal conscious or anesthetized rats. When sympathetic nervous system activity is increased, as in heart failure and intense renal sympathetic nerve stimulation, respectively, a small contribution of NPY to maintenance of arterial pressure and to sympathetic renal vasoconstrictor responses may be identified.

  20. Internal Progressive Failure in Deep-Seated Landslides

    NASA Astrophysics Data System (ADS)

    Yerro, Alba; Pinyol, Núria M.; Alonso, Eduardo E.

    2016-06-01

    Except for simple sliding motions, the stability of a slope does not depend only on the resistance of the basal failure surface. It is affected by the internal distortion of the moving mass, which plays an important role on the stability and post-failure behaviour of a landslide. The paper examines the stability conditions and the post-failure behaviour of a compound landslide whose geometry is inspired by one of the representative cross-sections of Vajont landslide. The brittleness of the mobilized rock mass was described by a strain-softening Mohr-Coulomb model, whose parameters were derived from previous contributions. The analysis was performed by means of a MPM computer code, which is capable of modelling the whole instability procedure in a unified calculation. The gravity action has been applied to initialize the stress state. This step mobilizes part of the strength along a shearing band located just above the kink of the basal surface, leading to the formation a kinematically admissible mechanism. The overall instability is triggered by an increase of water level. The increase of pore water pressures reduces the effective stresses within the slope and it leads to a progressive failure mechanism developing along an internal shearing band which controls the stability of the compound slope. The effect of the basal shearing resistance has been analysed during the post-failure stage. If no shearing strength is considered (as predicted by a thermal pressurization analysis), the model predicts a response similar to actual observations, namely a maximum sliding velocity of 25 m/s and a run-out close to 500 m.

  1. The utility of levosimendan in the treatment of heart failure.

    PubMed

    Lehtonen, Lasse; Põder, Pentti

    2007-01-01

    Calcium sensitizers are a new group of inotropic drugs. Levosimendan is the only calcium sensitizer in clinical use in Europe. Its mechanism of action includes both calcium sensitization of contractile proteins and the opening of adenosine triphosphate (ATP)-dependent potassium channels as mechanism of vasodilation. The combination of K-channel opening with positive inotropy offers potential benefits in comparison to currently available intravenous inotropes, since K-channel opening protects myocardium during ischemia. Due to the calcium-dependent binding of levosimendan to troponin C, the drug increases contractility without negative lusitropic effects. In patients with heart failure levosimendan dose-dependently increases cardiac output and reduces pulmonary capillary wedge pressure. Since levosimendan has an active metabolite OR-1896 with a half-life of some 80 hours, the duration of the hemodynamic effects significantly exceeds the 1-hour half-life of the parent compound. The hemodynamic effects of the levosimendan support its use in acute and postoperative heart failure. Several moderate-size trials (LIDO, RUSSLAN, CASINO) have previously suggested that the drug might even improve the prognosis of patients with decompensated heart failure. These trials were carried out in patients with high filling pressures. Recently two larger trials (SURVIVE and REVIVE) in patients who were hospitalized because of worsening heart failure have been finalized. These trials did not require filling pressures to be measured. The two trials showed that levosimendan improves the symptoms of heart failure, but does not improve survival. The results raise the question whether a 24-hour levosimendan infusion can be used without invasive hemodynamic monitoring.

  2. The hypertension of autonomic failure and its treatment

    NASA Technical Reports Server (NTRS)

    Shannon, J.; Jordan, J.; Costa, F.; Robertson, R. M.; Biaggioni, I.

    1997-01-01

    We studied the incidence and severity of supine hypertension in 117 patients with severe primary autonomic failure presenting to a referral center over a 9-year period. Patients were uniformly characterized by disabling orthostatic hypotension, lack of compensatory heart rate increase, abnormal autonomic function tests, and unresponsive plasma norepinephrine. Fifty-four patients had isolated autonomic impairment (pure autonomic failure). Sixty-three patients had central nervous system involvement in addition to autonomic impairment (multiple-system atrophy). Patients were studied off medications, in a metabolic ward, and on a controlled diet containing 150 mEq of sodium. Fifty-six percent of patients had supine diastolic blood pressure > or =90 mm Hg. The prevalence of hypertension was slightly greater in females (63%) than in males (52%). Potential mechanisms responsible for this hypertension were investigated. No correlation was found between blood volume and blood pressure. Similarly, plasma norepinephrine (92+/-15 pg/mL) and plasma renin activity (0.3+/-0.05 ng/mL per hour) were very low in the subset of patients with pure autonomic failure and supine hypertension (mean systolic/diastolic pressure, 177 +/- 6/108 +/- 2 mm Hg, range 167/97 to 219/121). Supine hypertension represents a challenge in the treatment of orthostatic hypotension. We found these patients to be particularly responsive to the hypotensive effects of transdermal nitroglycerin. Doses ranging from 0.025 to 0.1 mg/h decreased systolic blood pressure by 36+/-7 mm Hg and may effectively treat supine hypertension overnight, but the dose should be individualized and used with caution.

  3. Failure mechanisms of fibrin-based surgical tissue adhesives

    NASA Astrophysics Data System (ADS)

    Sierra, David Hugh

    A series of studies was performed to investigate the potential impact of heterogeneity in the matrix of multiple-component fibrin-based tissue adhesives upon their mechanical and biomechanical properties both in vivo and in vitro. Investigations into the failure mechanisms by stereological techniques demonstrated that heterogeneity could be measured quantitatively and that the variation in heterogeneity could be altered both by the means of component mixing and delivery and by the formulation of the sealant. Ex vivo tensile adhesive strength was found to be inversely proportional to the amount of heterogeneity. In contrast, in vivo tensile wound-closure strength was found to be relatively unaffected by the degree of heterogeneity, while in vivo parenchymal organ hemostasis in rabbits was found to be affected: greater heterogeneity appeared to correlate with an increase in hemostasis time and amount of sealant necessary to effect hemostasis. Tensile testing of the bulk sealant showed that mechanical parameters were proportional to fibrin concentration and that the physical characteristics of the failure supported a ductile mechanism. Strain hardening as a function of percentage of strain, and strain rate was observed for both concentrations, and syneresis was observed at low strain rates for the lower fibrin concentration. Blister testing demonstrated that burst pressure and failure energy were proportional to fibrin concentration and decreased with increasing flow rate. Higher fibrin concentration demonstrated predominately compact morphology debonds with cohesive failure loci, demonstrating shear or viscous failure in a viscoelastic rubbery adhesive. The lower fibrin concentration sealant exhibited predominately fractal morphology debonds with cohesive failure loci, supporting an elastoviscous material condition. The failure mechanism for these was hypothesized and shown to be flow-induced ductile fracture. Based on these findings, the failure mechanism was

  4. The SMART personalised self-management system for congestive heart failure: results of a realist evaluation.

    PubMed

    Bartlett, Yvonne K; Haywood, Annette; Bentley, Claire L; Parker, Jack; Hawley, Mark S; Mountain, Gail A; Mawson, Susan

    2014-11-25

    Technology has the potential to provide support for self-management to people with congestive heart failure (CHF). This paper describes the results of a realist evaluation of the SMART Personalised Self-Management System (PSMS) for CHF. The PSMS was used, at home, by seven people with CHF. Data describing system usage and usability as well as questionnaire and interview data were evaluated in terms of the context, mechanism and outcome hypotheses (CMOs) integral to realist evaluation. The CHF PSMS improved heart failure related knowledge in those with low levels of knowledge at baseline, through providing information and quizzes. Furthermore, participants perceived the self-regulatory aspects of the CHF PSMS as being useful in encouraging daily walking. The CMOs were revised to describe the context of use, and how this influences both the mechanisms and the outcomes. Participants with CHF engaged with the PSMS despite some technological problems. Some positive effects on knowledge were observed as well as the potential to assist with changing physical activity behaviour. Knowledge of CHF and physical activity behaviour change are important self-management targets for CHF, and this study provides evidence to direct the further development of a technology to support these targets.

  5. Interhospital transfer of children in respiratory failure: a clinician interview qualitative study.

    PubMed

    Odetola, Folafoluwa O; Anspach, Renee R; Han, Yong Y; Clark, Sarah J

    2017-02-01

    To investigate the decision making underlying transfer of children with respiratory failure from level II to level I pediatric intensive care unit care. Interviews with 19 eligible level II pediatric intensive care unit physicians about a hypothetical scenario of a 2-year-old girl in respiratory failure: RESULTS: At baseline, indices critical to management were as follows: OI (53%), partial pressure of oxygen in arterial blood (Pao 2 )/Fio 2 (32%), and inflation pressure (16%). Poor clinical response was signified by high OI, inflation pressure, and Fio 2 , and low Pao 2 /Fio 2 . At EP 1, 18 of 19 respondents would initiate high-frequency oscillatory ventilation, and 1 would transfer. At EP 2, 15 of 18 respondents would maintain high-frequency oscillatory ventilation, 9 of them calling to discuss transfer. All respondents would transfer if escalated therapies failed to reverse the patient's clinical deterioration. Interhospital transfer of children in respiratory failure is triggered by poor response to escalation of locally available care modalities. This finding provides new insight into decision making underlying interhospital transfer of children with respiratory failure. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Effect of Pore Pressure on Slip Failure of an Impermeable Fault: A Coupled Micro Hydro-Geomechanical Model

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Juanes, R.

    2015-12-01

    The geomechanical processes associated with subsurface fluid injection/extraction is of central importance for many industrial operations related to energy and water resources. However, the mechanisms controlling the stability and slip motion of a preexisting geologic fault remain poorly understood and are critical for the assessment of seismic risk. In this work, we develop a coupled hydro-geomechanical model to investigate the effect of fluid injection induced pressure perturbation on the slip behavior of a sealing fault. The model couples single-phase flow in the pores and mechanics of the solid phase. Granular packs (see example in Fig. 1a) are numerically generated where the grains can be either bonded or not, depending on the degree of cementation. A pore network is extracted for each granular pack with pore body volumes and pore throat conductivities calculated rigorously based on geometry of the local pore space. The pore fluid pressure is solved via an explicit scheme, taking into account the effect of deformation of the solid matrix. The mechanics part of the model is solved using the discrete element method (DEM). We first test the validity of the model with regard to the classical one-dimensional consolidation problem where an analytical solution exists. We then demonstrate the ability of the coupled model to reproduce rock deformation behavior measured in triaxial laboratory tests under the influence of pore pressure. We proceed to study the fault stability in presence of a pressure discontinuity across the impermeable fault which is implemented as a plane with its intersected pore throats being deactivated and thus obstructing fluid flow (Fig. 1b, c). We focus on the onset of shear failure along preexisting faults. We discuss the fault stability criterion in light of the numerical results obtained from the DEM simulations coupled with pore fluid flow. The implication on how should faults be treated in a large-scale continuum model is also presented.

  7. Underground storage systems for high-pressure air and gases

    NASA Technical Reports Server (NTRS)

    Beam, B. H.; Giovannetti, A.

    1975-01-01

    This paper is a discussion of the safety and cost of underground high-pressure air and gas storage systems based on recent experience with a high-pressure air system installed at Moffett Field, California. The system described used threaded and coupled oil well casings installed vertically to a depth of 1200 ft. Maximum pressure was 3000 psi and capacity was 500,000 lb of air. A failure mode analysis is presented, and it is shown that underground storage offers advantages in avoiding catastrophic consequences from pressure vessel failure. Certain problems such as corrosion, fatigue, and electrolysis are discussed in terms of the economic life of such vessels. A cost analysis shows that where favorable drilling conditions exist, the cost of underground high-pressure storage is approximately one-quarter that of equivalent aboveground storage.

  8. Wind Turbine Failures - Tackling current Problems in Failure Data Analysis

    NASA Astrophysics Data System (ADS)

    Reder, M. D.; Gonzalez, E.; Melero, J. J.

    2016-09-01

    The wind industry has been growing significantly over the past decades, resulting in a remarkable increase in installed wind power capacity. Turbine technologies are rapidly evolving in terms of complexity and size, and there is an urgent need for cost effective operation and maintenance (O&M) strategies. Especially unplanned downtime represents one of the main cost drivers of a modern wind farm. Here, reliability and failure prediction models can enable operators to apply preventive O&M strategies rather than corrective actions. In order to develop these models, the failure rates and downtimes of wind turbine (WT) components have to be understood profoundly. This paper is focused on tackling three of the main issues related to WT failure analyses. These are, the non-uniform data treatment, the scarcity of available failure analyses, and the lack of investigation on alternative data sources. For this, a modernised form of an existing WT taxonomy is introduced. Additionally, an extensive analysis of historical failure and downtime data of more than 4300 turbines is presented. Finally, the possibilities to encounter the lack of available failure data by complementing historical databases with Supervisory Control and Data Acquisition (SCADA) alarms are evaluated.

  9. Competitive evaluation of failure detection algorithms for strapdown redundant inertial instruments

    NASA Technical Reports Server (NTRS)

    Wilcox, J. C.

    1973-01-01

    Algorithms for failure detection, isolation, and correction of redundant inertial instruments in the strapdown dodecahedron configuration are competitively evaluated in a digital computer simulation that subjects them to identical environments. Their performance is compared in terms of orientation and inertial velocity errors and in terms of missed and false alarms. The algorithms appear in the simulation program in modular form, so that they may be readily extracted for use elsewhere. The simulation program and its inputs and outputs are described. The algorithms, along with an eight algorithm that was not simulated, also compared analytically to show the relationships among them.

  10. Evaluation of neutrophil/leukocyte ratio and organ failure score as predictors of reversibility and survival following an acute-on-chronic liver failure event.

    PubMed

    Agiasotelli, Danai; Alexopoulou, Alexandra; Vasilieva, Larisa; Kalpakou, Georgia; Papadaki, Sotiria; Dourakis, Spyros P

    2016-05-01

    Acute-on-chronic liver failure (ACLF) is defined as an acute deterioration of liver disease with high mortality in patients with cirrhosis. The early mortality in ACLF is associated with organ failure and high leukocyte count. The time needed to reverse this condition and the factors affecting mortality after the early 30-day-period were evaluated. One hundred and ninety-seven consecutive patients with cirrhosis were included. Patients were prospectively followed up for 180 days. ACLF was diagnosed in 54.8% of the patients. Infection was the most common precipitating event in patients with ACLF. On multivariate analysis, only the neutrophil/leukocyte ratio and Chronic Liver Failure Consortium Organ Failure (CLIF-C OF) score were associated with mortality. Hazard ratios for mortality of patients with ACLF compared with those without at different time end-points post-enrollment revealed that the relative risk of death in the ACLF group was 8.54 during the first 30-day period and declined to 1.94 during the second period of observation. The time varying effect of neutrophil/leukocyte ratio and CLIF-C score was negative (1% and 18% decline in the hazard ratio per month) while that of Model for End-Stage Liver Disease (MELD) was positive (3% increase in the hazard ratio per month). The condition of ACLF was reversible in patients who survived. During the 30-180-day period following the acute event, the probability of death in ACLF became gradually similar to the non-ACLF group. The impact of inflammatory response and organ failure on survival is powerful during the first 30-day period and weakens thereafter while that of MELD increases. © 2015 The Japan Society of Hepatology.

  11. Analysis of scale effect in compressive ice failure and implications for design

    NASA Astrophysics Data System (ADS)

    Taylor, Rocky Scott

    was observed. The pressure-thickness behavior was found to be well modeled by the power law relationships Pavg = 0.278 h-0.408 MPa and Pstd = 0.172h-0.273 MPa for the mean and standard deviation of pressure, respectively. To study theoretical aspects of spalling fracture and the pressure-thickness scale effect, probabilistic failure models have been developed. A probabilistic model based on Weibull theory (tensile stresses only) was first developed. Estimates of failure pressure obtained with this model were orders of magnitude higher than the pressures observed from benchmark data due to the assumption of only tensile failure. A probabilistic fracture mechanics (PFM) model including both tensile and compressive (shear) cracks was developed. Criteria for unstable fracture in tensile and compressive (shear) zones were given. From these results a clear theoretical scale effect in peak (spalling) pressure was observed. This scale effect followed the relationship Pp,th = 0.15h-0.50 MPa which agreed well with the benchmark data. The PFM model was applied to study the effect of ice edge shape (taper angle) and hpz eccentricity. Results indicated that specimens with flat edges spall at lower pressures while those with more tapered edges spall less readily. The mean peak (failure) pressure was also observed to decrease with increased eccentricity. It was concluded that hpzs centered about the middle of the ice thickness are the zones most likely to create the peak pressures that are of interest in design. Promising results were obtained using the PFM model, which provides strong support for continued research in the development and application of probabilistic fracture mechanics to the study of scale effects in compressive ice failure and to guide the development of methods for the estimation of design ice pressures.

  12. System Study: High-Pressure Coolant Injection 1998-2014

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schroeder, John Alton

    2015-12-01

    This report presents an unreliability evaluation of the high-pressure coolant injection system (HPCI) at 25 U.S. commercial boiling water reactors. Demand, run hours, and failure data from fiscal year 1998 through 2014 for selected components were obtained from the Institute of Nuclear Power Operations (INPO) Consolidated Events Database (ICES). The unreliability results are trended for the most recent 10 year period, while yearly estimates for system unreliability are provided for the entire active period. No statistically significant increasing or decreasing trends were identified in the HPCI results.

  13. System Study: High-Pressure Core Spray 1998-2014

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schroeder, John Alton

    2015-12-01

    This report presents an unreliability evaluation of the high-pressure core spray (HPCS) at eight U.S. commercial boiling water reactors. Demand, run hours, and failure data from fiscal year 1998 through 2014 for selected components were obtained from the Institute of Nuclear Power Operations (INPO) Consolidated Events Database (ICES). The unreliability results are trended for the most recent 10 year period, while yearly estimates for system unreliability are provided for the entire active period. No statistically significant increasing or decreasing trends were identified in the HPCS results.

  14. System Study: High-Pressure Safety Injection 1998-2014

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schroeder, John Alton

    2015-12-01

    This report presents an unreliability evaluation of the high-pressure safety injection system (HPSI) at 69 U.S. commercial nuclear power plants. Demand, run hours, and failure data from fiscal year 1998 through 2014 for selected components were obtained from the Institute of Nuclear Power Operations (INPO) Consolidated Events Database (ICES). The unreliability results are trended for the most recent 10 year period, while yearly estimates for system unreliability are provided for the entire active period. No statistically significant increasing or decreasing trends were identified in the HPSI results.

  15. The elasticity and failure of fluid-filled cellular solids: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Warner, M.; Thiel, B. L.; Donald, A. M.

    2000-02-01

    We extend and apply theories of filled foam elasticity and failure to recently available data on foods. The predictions of elastic modulus and failure mode dependence on internal pressure and on wall integrity are borne out by photographic evidence of distortion and failure under compressive loading and under the localized stress applied by a knife blade, and by mechanical data on vegetables differing only in their turgor pressure. We calculate the dry modulus of plate-like cellular solids and the cross over between dry-like and fully fluid-filled elastic response. The bulk elastic properties of limp and aging cellular solids are calculated for model systems and compared with our mechanical data, which also show two regimes of response. The mechanics of an aged, limp beam is calculated, thus offering a practical procedure for comparing experiment and theory. This investigation also thereby offers explanations of the connection between turgor pressure and crispness and limpness of cellular materials.

  16. The elasticity and failure of fluid-filled cellular solids: theory and experiment.

    PubMed

    Warner, M; Thiel, B L; Donald, A M

    2000-02-15

    We extend and apply theories of filled foam elasticity and failure to recently available data on foods. The predictions of elastic modulus and failure mode dependence on internal pressure and on wall integrity are borne out by photographic evidence of distortion and failure under compressive loading and under the localized stress applied by a knife blade, and by mechanical data on vegetables differing only in their turgor pressure. We calculate the dry modulus of plate-like cellular solids and the cross over between dry-like and fully fluid-filled elastic response. The bulk elastic properties of limp and aging cellular solids are calculated for model systems and compared with our mechanical data, which also show two regimes of response. The mechanics of an aged, limp beam is calculated, thus offering a practical procedure for comparing experiment and theory. This investigation also thereby offers explanations of the connection between turgor pressure and crispness and limpness of cellular materials.

  17. The elasticity and failure of fluid-filled cellular solids: Theory and experiment

    PubMed Central

    Warner, M.; Thiel, B. L.; Donald, A. M.

    2000-01-01

    We extend and apply theories of filled foam elasticity and failure to recently available data on foods. The predictions of elastic modulus and failure mode dependence on internal pressure and on wall integrity are borne out by photographic evidence of distortion and failure under compressive loading and under the localized stress applied by a knife blade, and by mechanical data on vegetables differing only in their turgor pressure. We calculate the dry modulus of plate-like cellular solids and the cross over between dry-like and fully fluid-filled elastic response. The bulk elastic properties of limp and aging cellular solids are calculated for model systems and compared with our mechanical data, which also show two regimes of response. The mechanics of an aged, limp beam is calculated, thus offering a practical procedure for comparing experiment and theory. This investigation also thereby offers explanations of the connection between turgor pressure and crispness and limpness of cellular materials. PMID:10660680

  18. Vasodilators and α-adrenoceptor antagonists in hypertension and heart failure

    PubMed Central

    Taylor, S. H.

    1981-01-01

    1 The mechanism of the increase in arteriolar resistance in hypertension and heart failure is differently derived. In hypertension, venous compliance is normal and the concentric narrowing of the arteriolar resistance vessels is `anatomical'; it is not due to increased stimulation or enhanced sensitivity of the vascular smooth muscle. In heart failure narrowing of both the arteriolar resistance and venous capacitance vessels derives predominantly from increased sympathoadrenal stimulation of α1-adrenoceptors in the vascular smooth muscle. 2 Vasodilator drugs which relax vascular smooth muscle differ widely in their site of activity. None are entirely specific for arteries, arterioles or veins, but they may be grouped for therapeutic convenience into those predominantly acting on arterioles (for example hydralazine) and those acting on veins (for example nitrates). 3 Control of the resting blood pressure in stable essential hypertension appears to be equally well achieved with non-specific arteriolar dilators (for example hydralazine, minoxidil, calcium antagonists) as those with specific α1-adrenoceptor blocking properties (for example prazosin, indoramin). Pressure surges due to dynamic exercise and mental stress are little influenced by either category of drug. In contrast, α-adrenoceptor antagonists appear to be capable of partly suppressing increase in ambulatory pressure and the pressor responses to isometric exercise and cold, particularly in patients pre-treated with β-blocking drugs. 4 In acute heart failure, non-selective α-blocking drugs (for example phentolamine) produce an equal reduction in left ventricular filling pressure but greater increase in cardiac output than vasodilator drugs with a more balanced relaxing effect on arterioles and venules. 5 In chronic heart failure, the little information available indicates that non-selective arteriolar dilatation is probably associated with a greater increase in cardiac output lesser reduction in left

  19. Mechanics of rainfall-induced flow failure in unsaturated shallow slopes (Invited)

    NASA Astrophysics Data System (ADS)

    Buscarnera, G.

    2013-12-01

    The increase in pore water pressure due to rain infiltration can be a dominant component in the activation of slope instabilities. This work shows an application of the theory of material stability to the triggering analysis of this important class of natural hazards. The goal is to identify the mechanisms through which the process of rain infiltration promotes instabilities of the flow-type in the soil covers. The interplay between increase in pore water pressure and failure mechanisms is investigated at material point level. To account for multiple failure mechanisms, the second-order energy input is linked to the controllability theory and used to define different types of stability indices, each associated with a specific mode of slope failure. It is shown that the theory can be used to assess both shear failure and static liquefaction in saturated and unsaturated soil covers. In particular, it is shown that these instability modes are regulated by the hydro-mechanical characteristics of the soil covers, as well as by their mutual coupling. This finding discloses the importance of the constitutive functions that simulate the interaction between the response of the solid skeleton and the fluid-retention characteristics of the soil. As a consequence, they suggest that even material properties that are not be to directly associated with the shearing resistance (e.g., the potential for wetting compaction) may play a role in the initiation of catastrophic slope failures. According to the proposed interpretation, the process of pore pressure increase can be seen as the trigger of uncontrolled strains, which can anticipate the onset of frictional failure and promote a solid-to-fluid transition.

  20. Cost-effectiveness of Out-of-Hospital Continuous Positive Airway Pressure for Acute Respiratory Failure.

    PubMed

    Thokala, Praveen; Goodacre, Steve; Ward, Matt; Penn-Ashman, Jerry; Perkins, Gavin D

    2015-05-01

    We determine the cost-effectiveness of out-of-hospital continuous positive airway pressure (CPAP) compared with standard care for adults presenting to emergency medical services with acute respiratory failure. We developed an economic model using a United Kingdom health care system perspective to compare the costs and health outcomes of out-of-hospital CPAP to standard care (inhospital noninvasive ventilation) when applied to a hypothetical cohort of patients with acute respiratory failure. The model assigned each patient a probability of intubation or death, depending on the patient's characteristics and whether he or she had out-of-hospital CPAP or standard care. The patients who survived accrued lifetime quality-adjusted life-years (QALYs) and health care costs according to their age and sex. Costs were accrued through intervention and hospital treatment costs, which depended on patient outcomes. All results were converted into US dollars, using the Organisation for Economic Co-operation and Development purchasing power parities rates. Out-of-hospital CPAP was more effective than standard care but was also more expensive, with an incremental cost-effectiveness ratio of £20,514 per QALY ($29,720/QALY) and a 49.5% probability of being cost-effective at the £20,000 per QALY ($29,000/QALY) threshold. The probability of out-of-hospital CPAP's being cost-effective at the £20,000 per QALY ($29,000/QALY) threshold depended on the incidence of eligible patients and varied from 35.4% when a low estimate of incidence was used to 93.8% with a high estimate. Variation in the incidence of eligible patients also had a marked influence on the expected value of sample information for a future randomized trial. The cost-effectiveness of out-of-hospital CPAP is uncertain. The incidence of patients eligible for out-of-hospital CPAP appears to be the key determinant of cost-effectiveness. Copyright © 2015 American College of Emergency Physicians. Published by Elsevier Inc. All

  1. Cost-effectiveness of Out-of-Hospital Continuous Positive Airway Pressure for Acute Respiratory Failure

    PubMed Central

    Thokala, Praveen; Goodacre, Steve; Ward, Matt; Penn-Ashman, Jerry; Perkins, Gavin D.

    2015-01-01

    Study objective We determine the cost-effectiveness of out-of-hospital continuous positive airway pressure (CPAP) compared with standard care for adults presenting to emergency medical services with acute respiratory failure. Methods We developed an economic model using a United Kingdom health care system perspective to compare the costs and health outcomes of out-of-hospital CPAP to standard care (inhospital noninvasive ventilation) when applied to a hypothetical cohort of patients with acute respiratory failure. The model assigned each patient a probability of intubation or death, depending on the patient’s characteristics and whether he or she had out-of-hospital CPAP or standard care. The patients who survived accrued lifetime quality-adjusted life-years (QALYs) and health care costs according to their age and sex. Costs were accrued through intervention and hospital treatment costs, which depended on patient outcomes. All results were converted into US dollars, using the Organisation for Economic Co-operation and Development purchasing power parities rates. Results Out-of-hospital CPAP was more effective than standard care but was also more expensive, with an incremental cost-effectiveness ratio of £20,514 per QALY ($29,720/QALY) and a 49.5% probability of being cost-effective at the £20,000 per QALY ($29,000/QALY) threshold. The probability of out-of-hospital CPAP’s being cost-effective at the £20,000 per QALY ($29,000/QALY) threshold depended on the incidence of eligible patients and varied from 35.4% when a low estimate of incidence was used to 93.8% with a high estimate. Variation in the incidence of eligible patients also had a marked influence on the expected value of sample information for a future randomized trial. Conclusion The cost-effectiveness of out-of-hospital CPAP is uncertain. The incidence of patients eligible for out-of-hospital CPAP appears to be the key determinant of cost-effectiveness. PMID:25737210

  2. LCZ696 (Valsartan/Sacubitril)--A Possible New Treatment for Hypertension and Heart Failure.

    PubMed

    Andersen, Mathilde Borring; Simonsen, Ulf; Wehland, Markus; Pietsch, Jessica; Grimm, Daniela

    2016-01-01

    The aim of this MiniReview was to introduce the newly invented dual-acting drug valsartan/sacubitril (LCZ696), which combines an angiotensin receptor blocker (valsartan) with sacubitril, a specific inhibitor of the neutral endopeptidase (NEP) that degrades vasoactive peptides, including natriuretic peptides ANP and BNP, but also glucagon, enkephalins and bradykinin, among others. The MiniReview presents the data of four available trials NCT01193101, NCT00549770, NCT00887588 and NCT01035255 and provides the current knowledge about LCZ696 effects in patients with hypertension and heart failure. Presently, patients suffering from hypertension and heart failure are treated with ACE inhibitors or angiotensin receptor antagonists often in combination with other drugs. These current medications lead to a reduction in blood pressure in hypertensive patients and a decreased mortality and morbidity in patients with heart failure with reduced ejection fraction, but not in patients with heart failure with preserved ejection fraction. LCZ696 had been tested to utilize the beneficial properties of natriuretic peptides in combination with angiotensin receptor antagonism. It induces even greater blood pressure reductions and decreased mortality and morbidity in patients with heart failure with reduced ejection fraction, while patients with heart failure with preserved ejection fraction show lowered blood pressure and decreased NT-pro-BNP levels. Although long-term studies remain to be performed, these initial data suggest that there is a potential clinical benefit of LCZ696 in the treatment of hypertension and heart failure. © 2015 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

  3. Causes of catastrophic failure in complex systems

    NASA Astrophysics Data System (ADS)

    Thomas, David A.

    2010-08-01

    Root causes of mission critical failures and major cost and schedule overruns in complex systems and programs are studied through the post-mortem analyses compiled for several examples, including the Hubble Space Telescope, the Challenger and Columbia Shuttle accidents, and the Three Mile Island nuclear power plant accident. The roles of organizational complexity, cognitive biases in decision making, the display of quantitative data, and cost and schedule pressure are all considered. Recommendations for mitigating the risk of similar failures in future programs are also provided.

  4. [Refractory heart failure. Models of hospital, ambulatory, and home management].

    PubMed

    Oliva, Fabrizio; Alunni, Gianfranco

    2002-08-01

    Chronic heart failure is an enormous and growing public health problem and is reaching epidemic proportions. Its economic impact is dramatic; two thirds of expenses are for hospitalizations and relatively little is being spent for medications and outpatient visits. Most of the hospitalizations, deaths and costs are incurred by a relatively small minority of patients who may be described as having "complex", "advanced", "refractory" or "end-stage" heart failure; however, in essence they are patients who have severe symptoms and/or recurrent hospitalizations and/or emergency department visits despite maximal oral therapy. Many of the recommendations regarding the management of these patients are based more on experience than on evidence from controlled trials. This, because such patients require an individualized therapy which limits their inclusion in large trials and because support is less easily available when testing specific strategies than when testing specific agents. Improving the treatment of this group of patients by optimizing their medical regimen, aggressive monitoring and providing early intervention to avert heart failure can reduce their morbidity, mortality and costs of care. Refractory heart failure is not a single disease and it is extremely unlikely that all patients should be treated in a similar manner; before selecting the appropriate therapy, the clinician must categorize and profile the patient. The first step should be a re-evaluation of the previous treatment because many patients are treated suboptimally. It is also important to identify reversible or precipitating factors. For patients with advanced heart failure, the initial goal of therapy is to improve symptoms; the next goal is to maintain the improvement and to prevent later deterioration. The appropriate treatment plan will reflect the presence of comorbidities, the patients' history regarding previous responses to therapy, their own expectations with regard to daily life. The most

  5. Pressure melting and ice skating

    NASA Astrophysics Data System (ADS)

    Colbeck, S. C.

    1995-10-01

    Pressure melting cannot be responsible for the low friction of ice. The pressure needed to reach the melting temperature is above the compressive failure stress and, if it did occur, high squeeze losses would result in very thin films. Pure liquid water cannot coexist with ice much below -20 °C at any pressure and friction does not increase suddenly in that range. If frictional heating and pressure melting contribute equally, the length of the wetted contact could not exceed 15 μm at a speed of 5 m/s, which seems much too short. If pressure melting is the dominant process, the water films are less than 0.08 μm thick because of the high pressures.

  6. Evaluation of Left Ventricular Diastolic Dysfunction with Early Systolic Dysfunction Using Two-Dimensional Speckle Tracking Echocardiography in Canine Heart Failure Model.

    PubMed

    Wu, Wei-Chun; Ma, Hong; Xie, Rong-Ai; Gao, Li-Jian; Tang, Yue; Wang, Hao

    2016-04-01

    This study evaluated the role of two-dimensional speckle tracking echocardiography (2DSTE) for predicting left ventricular (LV) diastolic dysfunction in pacing-induced canine heart failure. Pacing systems were implanted in 8 adult mongrel dogs, and continuous rapid right ventricular pacing (RVP, 240 beats/min) was maintained for 2 weeks. The obtained measurements from 2DSTE included global strain rate during early diastole (SRe) and during late diastole (SRa) in the longitudinal (L-SRe, L-SRa), circumferential (C-SRe, C-SRa), and radial directions (R-SRe, R-SRa). Changes in heart morphology were observed by light microscopy and transmission electron microscopy at 2 weeks. The onset of LV diastolic dysfunction with early systolic dysfunction occurred 3 days after RVP initiation. Most of the strain rate imaging indices were altered at 1 or 3 days after RVP onset and continued to worsen until heart failure developed. Light and transmission electron microscopy showed myocardial vacuolar degeneration and mitochondrial swelling in the left ventricular at 2 weeks after RVP onset. Pearson's correlation analysis revealed that parameters of conventional echocardiography and 2DSTE showed moderate correlation with LV pressure parameters, including E/Esep' (r = 0.58, P < 0.01), L-SRe (r = -0.58, P < 0.01), E/L-SRe (r = 0.65, P < 0.01), and R-SRe (r = 0.53, P < 0.01). ROC curves analysis showed that these indices of conventional echocardiography and strain rate imaging could effectively predict LV diastolic dysfunction (area under the curve: E/Esep' 0.78; L-SRe 0.84; E/L-SRe 0.80; R-SRe 0.80). 2DSTE was a sensitive and accurate technique that could be used for predicting LV diastolic dysfunction in canine heart failure model. © 2015, Wiley Periodicals, Inc.

  7. Congestive kidney failure in cardiac surgery: the relationship between central venous pressure and acute kidney injury.

    PubMed

    Gambardella, Ivancarmine; Gaudino, Mario; Ronco, Claudio; Lau, Christopher; Ivascu, Natalia; Girardi, Leonard N

    2016-11-01

    Acute kidney injury (AKI) in cardiac surgery has traditionally been linked to reduced arterial perfusion. There is ongoing evidence that central venous pressure (CVP) has a pivotal role in precipitating acute renal dysfunction in cardiac medical and surgical settings. We can regard this AKI driven by systemic venous hypertension as 'kidney congestive failure'. In the cardiac surgery population as a whole, when the CVP value reaches the threshold of 14 mmHg in postoperative period, the risk of AKI increases 2-fold with an odds ratio (OR) of 1.99, 95% confidence interval (95% CI) of 1.16-3.40. In cardiac surgery subsets where venous hypertension is a hallmark feature, the incidence of AKI is higher (tricuspid disease 30%, carcinoid valve disease 22%). Even in the non-chronically congested coronary artery bypass population, CVP measured 6 h postoperatively showed significant association to renal failure: risk-adjusted OR for AKI was 5.5 (95% CI 1.93-15.5; P = 0.001) with every 5 mmHg rise in CVP for patients with CVP <9 mmHg; for CVP increments of 5 mmHg above the threshold of 9 mmHg, the risk-adjusted OR for AKI was 1.3 (95% CI 1.01-1.65; P = 0.045). This and other clinical evidence are discussed along with the underlying pathophysiological mechanisms, involving the supremacy of volume receptors in regulating the autonomic output in hypervolaemia, and the regional effect of venous congestion on the nephron. The effect of CVP on renal function was found to be modulated by ventricular function class, aetiology and acuity of venous congestion. Evidence suggests that acute increases of CVP should be actively treated to avoid a deterioration of the renal function, particularly in patients with poor ventricular fraction. Besides, the practice of treating right heart failure with fluid loading should be avoided in favour of other ways to optimize haemodynamics in this setting, because of the detrimental effects on the kidney function. © The Author 2016. Published by Oxford

  8. Effects of body position on the carbon monoxide diffusing capacity in patients with chronic heart failure: relation to hemodynamic changes.

    PubMed

    Faggiano, P; D'Aloia, A; Simoni, P; Gualeni, A; Foglio, K; Ambrosino, N; Giordano, A

    1998-01-01

    Pulmonary diffusion has been found to be reduced in patients with congestive heart failure. The effects of postural changes on the diffusing capacity had been evaluated in healthy subjects, but not in patients with heart failure. The aim of this study was to evaluate the posture-induced changes in diffusing capacity in patients with chronic heart failure and their relation to the hemodynamic profile. The pulmonary carbon monoxide diffusing capacity (DLCO) was measured in the supine position, with 20 degrees passive head elevation, and in the sitting position, both postures maintained for 10 min, in a group of 32 male patients with mild to moderate chronic heart failure due to left ventricular systolic dysfunction (ejection fraction <35%). On a separate day, in the absence of any changes in clinical status and therapy, the hemodynamic parameters were measured by right-heart catheterization. The sequence of postures was assigned randomly. The mean values of DLCO were slightly reduced and did not differ in the two positions (20.3 +/- 5.7 vs. 19.4 +/- 5.6 ml/min/mm Hg, 77 +/- 23 vs. 75 +/- 20% of predicted, respectively). The patients were then subdivided according to changes in DLCO from the supine to the sitting position: DLCO increased (+23%) in 9 patients (28%, group 1), decreased (-17.5%) in 17 patients (53%, group 2), and remained within the coefficient of reproducibility ( +/- 5 %) in 6 patients (group 3). As compared with group 2, group 1 patients showed a significant increase in mean pulmonary artery pressure (+7 vs. -15%, p < 0.01) and pulmonary capillary wedge pressure (+8 vs. -22%, p < 0.005) from the supine to the sitting position, while the cardiac index showed a smaller - but not significant - decrease in group 1 (-5 vs. -12%). The percent changes in DLCO significantly correlated with changes in pulmonary capillary wedge (r = 0.54, p < 0.0005) and mean pulmonary artery (r = 0.47, p < 0.005) pressures. In chronic heart failure postural changes may induce

  9. Oral theophylline in chronic heart failure

    PubMed Central

    Al-Damluji, S.; Johnston, A.; Spurrell, R. A. J.; Nathan, A. W.; Banim, S. O.; Camm, A. J.

    1982-01-01

    Theophylline choline 600 mg was given as a single oral dose to nine patients in chronic left ventricular failure due to myocardial dysfunction. Cardiac output, left ventricular filling pressure (LVFP) and right atrial pressure (RAP) were measured with a pulmonary artery thermodilution catheter for the following 3 hr. Continuous recordings of cardiac rhythm were made throughout the study. Mean cardiac index increased from 1·75 (±0·14 s.e. mean) to 2·04 (±0·11) 1/min/m2 (P<0·02), mean LVFP fell from 27 (±2·4) to 22 (±1·5) mmHg (P<0·01), mean RAP fell from 5 (±1·3) to 3 (±2·0) mmHg (P<0·05) and mean systemic arterial pressure rose from 80 (±3) to 86 (±3·5) mmHg (P<0·05). There were no significant changes in heart rate or systemic vascular resistance; thus the increase in cardiac output was probably due to a positive inotropic effect. Side effects were seen in two patients, both of whom proved to have toxic plasma theophylline concentrations. This study demonstrated a beneficial acute haemodynamic effect of oral theophylline in chronic cardiac failure. PMID:7111101

  10. Acute Respiratory Failure in Renal Transplant Recipients: A Single Intensive Care Unit Experience.

    PubMed

    Ulas, Aydin; Kaplan, Serife; Zeyneloglu, Pinar; Torgay, Adnan; Pirat, Arash; Haberal, Mehmet

    2015-11-01

    Frequency of pulmonary complications after renal transplant has been reported to range from 3% to 17%. The objective of this study was to evaluate renal transplant recipients admitted to an intensive care unit to identify incidence and cause of acute respiratory failure in the postoperative period and compare clinical features and outcomes between those with and without acute respiratory failure. We retrospectively screened the data of 540 consecutive adult renal transplant recipients who received their grafts at a single transplant center and included those patients admitted to an intensive care unit during this period for this study. Acute respiratory failure was defined as severe dyspnea, respiratory distress, decreased oxygen saturation, hypoxemia or hypercapnia on room air, or requirement of noninvasive or invasive mechanical ventilation. Among the 540 adult renal transplant recipients, 55 (10.7%) were admitted to an intensive care unit, including 26 (47.3%) admitted for acute respiratory failure. Median time from transplant to intensive care unit admission was 10 months (range, 0-67 mo). The leading causes of acute respiratory failure were bacterial pneumonia (56%) and cardiogenic pulmonary edema (44%). Mean partial pressure of arterial oxygen to fractional inspired oxygen ratio was 174 ± 59, invasive mechanical ventilation was used in 13 patients (50%), and noninvasive mechanical ventilation was used in 8 patients (31%). The overall mortality was 16.4%. Acute respiratory failure was the reason for intensive care unit admission in almost half of our renal transplant recipients. Main causes of acute respiratory failure were bacterial pneumonia and cardiogenic pulmonary edema. Mortality of patients admitted for acute respiratory failure was similar to those without acute respiratory failure.

  11. Systolic Blood Pressure and Incident Heart Failure in the Elderly

    PubMed Central

    Butler, Javed; Kalogeropoulos, Andreas P.; Georgiopoulou, Vasiliki V.; Bibbins-Domingo, Kirsten; Najjar, Samer S.; Sutton-Tyrrell, Kim C.; Harris, Tamara B.; Kritchevsky, Stephen B.; Lloyd-Jones, Donald M.; Newman, Anne B.; Psaty, Bruce M.

    2013-01-01

    Objectives The exact form of the association between systolic blood pressure (SBP) and heart failure (HF) risk in the elderly remains incompletely defined, especially in individuals not receiving antihypertensive medications. Our aim was to examine the association between SBP and HF risk in the elderly. Design Competing-risks proportional hazards modeling of incident HF risk, utilizing 10-year follow-up data from two NIH-sponsored cohort studies; the Cardiovascular Health Study (inception: 1989-90 and 1992-93) and the Health ABC Study (inception: 1997-98). Setting Community-based cohorts. Participants 4408 participants (age, 72.8 [4.9] years; 53.1% women, 81.7% white; 18.3% black) without prevalent HF and not receiving antihypertensive medications at baseline. Main outcome measures Incident HF, defined as first adjudicated hospitalisation for HF. Results Over 10 years, 493 (11.1%) participants developed HF. Prehypertension (120-139 mmHg), stage 1 (140-159 mmHg), and stage 2 (≥160 mmHg) hypertension were associated with escalating HF risk; hazard ratios vs. optimal SBP (<120 mmHg) in competing-risks models controlling for clinical characteristics were 1.63 (95% CI, 1.23-2.16; P=0.001), 2.21 (95% CI, 1.65-2.96; P<0.001), and 2.60 (95% CI, 1.85-364; P<0.001), respectively. Overall 255 of 493 (51.7%) HF events occurred in participants with SBP <140 mm Hg at baseline. Increasing SBP was associated with higher HF risk in women than men; no race-SBP interaction was observed. In analyses with continuous SBP, HF risk had a continuous positive association with SBP to levels as low as 113 mmHg in men and 112 mmHg in women. Conclusions There is a continuous positive association between SBP and HF risk in the elderly for levels of SBP as low as <115 mmHg; over half of incident HF events occur in individuals with SBP <140 mmHg. PMID:21636845

  12. Analysis of a Turbine Blade Failure in a Military Turbojet Engine

    NASA Astrophysics Data System (ADS)

    Sahoo, Benudhar; Satpathy, R. K.; Panigrahi, S. K.

    2016-06-01

    This paper deals with failure analysis of a low-pressure turbine blade of a straight flow turbojet engine. The blade is made of a wrought precipitation hardened Nickel base superalloy with oxidation-resistant diffusion aluminizing coating. The failure mode is found to be fatigue with multiple cracks inside the blade having crack origin at metal carbides. In addition to the damage in the coating, carbide banding has been observed in few blades. Carbide banding may be defined as inclusions in the form of highly elongated along deformation direction. The size, shape and banding of carbides and their location critically affect the failure of blades. Carbon content needs to be optimized to reduce interdendritic segregation and thereby provide improved fatigue and stress rupture life. Hence, optimization of size, shape and distribution of carbides in the billet and forging parameters during manufacturing of blade play a vital role to eliminate/reduce extent of banding. Reference micrographs as acceptance criteria are essential for evaluation of raw material and blade. There is a need to define the acceptance criteria for carbide bandings and introduce more sensitive ultrasonic check during billet and on finished blade inspection.

  13. Browns Ferry Nuclear Plant: variation in test intervals for high-pressure coolant injection (HPCI) system

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Christie, R.F.; Stetkar, J.W.

    1985-01-01

    The change in availability of the high-pressure coolant injection system (HPCIS) due to a change in pump and valve test interval from monthly to quarterly was analyzed. This analysis started by using the HPCIS base line evaluation produced as part of the Browns Ferry Nuclear Plant (BFN) Probabilistic Risk Assessment (PRA). The base line evaluation showed that the dominant contributors to the unavailability of the HPCI system are hardware failures and the resultant downtime for unscheduled maintenance.

  14. Evaluation of marginal failures of dental composite restorations by acoustic emission analysis.

    PubMed

    Gu, Ja-Uk; Choi, Nak-Sam

    2013-01-01

    In this study, a nondestructive method based on acoustic emission (AE) analysis was developed to evaluate the marginal failure states of dental composite restorations. Three types of ring-shaped substrates, which were modeled after a Class I cavity, were prepared from polymethyl methacrylate, stainless steel, and human molar teeth. A bonding agent and a composite resin were applied to the ring-shaped substrates and cured by light exposure. At each time-interval measurement, the tooth substrate presented a higher number of AE hits than polymethyl methacrylate and steel substrates. Marginal disintegration estimations derived from cumulative AE hits and cumulative AE energy parameters showed that a signification portion of marginal gap formation was already realized within 1 min at the initial light-curing stage. Estimation based on cumulative AE energy gave a higher level of marginal failure than that based on AE hits. It was concluded that the AE analysis method developed in this study was a viable approach in predicting the clinical survival of dental composite restorations efficiently within a short test period.

  15. Respiratory sleep disorders in patients with congestive heart failure

    PubMed Central

    2015-01-01

    Respiratory sleep disorders (RSD) occur in about 40-50% of patients with symptomatic congestive heart failure (CHF). Obstructive sleep apnea (OSA) is considered a cause of CHF, whereas central sleep apnea (CSA) is considered a response to heart failure, perhaps even compensatory. In the setting of heart failure, continuous positive airway pressure (CPAP) has a definite role in treating OSA with improvements in cardiac parameters expected. However in CSA, CPAP is an adjunctive therapy to other standard therapies directed towards the heart failure (pharmacological, device and surgical options). Whether adaptive servo controlled ventilatory support, a variant of CPAP, is beneficial is yet to be proven. Supplemental oxygen therapy should be used with caution in heart failure, in particular, by avoiding hyperoxia as indicated by SpO2 values >95%. PMID:26380758

  16. Right Ventricular Failure Post LVAD Implantation Corrected with Biventricular Support: An In Vitro Model.

    PubMed

    Shehab, Sajad; Allida, Sabine M; Davidson, Patricia M; Newton, Phillip J; Robson, Desiree; Jansz, Paul C; Hayward, Christopher S

    Right ventricular failure after left ventricular assist device (LVAD) implantation is associated with high mortality. Management remains limited to pharmacologic therapy and temporary mechanical support. Delayed right ventricular assist device (RVAD) support after LVAD implantation is associated with poorer outcomes. With the advent of miniaturized, durable, continuous flow ventricular assist device systems, chronic RVAD and biventricular assist device (BiVAD) support has been used with some success. The purpose of this study was to assess combined BiVAD and LVAD with delayed RVAD support within a four-elemental mock circulatory loop (MCL) simulating the human cardiovascular system. Our hypothesis was that delayed continuous flow RVAD (RVAD) would produce similar hemodynamic and flow parameters to those of initial BiVAD support. Using the MCL, baseline biventricular heart failure with elevated right and left filling pressures with low cardiac output was simulated. The addition of LVAD within a biventricular configuration improved cardiac output somewhat, but was associated with persistent right heart failure with elevated right-sided filling pressures. The addition of an RVAD significantly improved LVAD outputs and returned filling pressures to normal throughout the circulation. In conclusion, RVAD support successfully restored hemodynamics and flow parameters of biventricular failure supported with isolated LVAD with persistent elevated right atrial pressure.

  17. Prognostic incremental role of right ventricular function in acute decompensation of advanced chronic heart failure.

    PubMed

    Frea, Simone; Pidello, Stefano; Bovolo, Virginia; Iacovino, Cristina; Franco, Erica; Pinneri, Francesco; Galluzzo, Alessandro; Volpe, Alessandra; Visconti, Massimiliano; Peirone, Andrea; Morello, Mara; Bergerone, Serena; Gaita, Fiorenzo

    2016-05-01

    The purpose of this study was to evaluate the additional prognostic value of echocardiography in acute decompensation of advanced chronic heart failure (CHF), focusing on right ventricular (RV) dysfunction and its interaction with loading conditions. Few data are available on the prognostic role of echocardiography in acute HF and on the significance of pulmonary hypertension in patients with severe RV failure. A total of 265 NYHA IV patients admitted for acute decompensation of advanced CHF (EF 22 ± 7%, systolic blood pressure 107 ± 20 mmHg) were prospectively enrolled. Fifty-nine patients met the primary composite endpoint of cardiac death, urgent heart transplantation, and urgent mechanical circulatory support implantation at 90 days. Pulmonary hypertension failed to predict events, while patients with a low transtricuspid systolic gradient (TR gradient <20 mmHg) showed a worse outcome [hazard ratio (HR) 2.37, 95% confidence interval (CI) 1.12-5.00, P = 0.02]. RV dysfunction [tricuspid annular plane systolic excursion (TAPSE) ≤14 mm] in the presence of a low TR gradient identified patients at higher risk of events (HR 2.97, 95% CI 1.19-7.41, P = 0.02). Multivariate analysis showed as best predictors of outcome low RV contraction pressure index (RVCPI), defined as TAPSE × TR gradient, and high estimated right atrial pressure (eRAP). Adding RVCPI (<400 mm*mmHg) and eRAP (≥20 mmHg) to conventional clinical (ADHERE risk tree and NT-proBNP) and echocardiographic risk evaluation resulted in an increase in net reclassification improvement of +19.1% and +20.1%, respectively (P = 0.01) and in c-statistic from 0.59 to 0.73 (P < 0.01). In acute decompensation of advanced CHF, pulmonary hypertension failed to predict events. The in-hospital and short-term prognosis can be better predicted by eRAP and RVCPI. © 2016 The Authors. European Journal of Heart Failure © 2016 European Society of Cardiology.

  18. Different acute cardiovascular stress in response to resistance exercise leading to failure versus not to failure in elderly women with and without hypertension--a pilot study.

    PubMed

    Tajra, Vitor; Vieira, Denis C L; Tibana, Ramires A; Teixeira, Tatiane G; Silva, Alessandro O; Farias, Darlan L; Nascimento, Dahan da C; de Sousa, Nuno M F; Willardson, Jeffrey; Prestes, Jonato

    2015-03-01

    The purpose of the present study was to compare the effects of resistance exercise (RE) leading to failure versus not to failure on 24-h blood pressure (BP) and rate-pressure product (RPP) responses in normotensive and hypertensive trained elderly women. Seven normotensive women and seven women with medically documented hypertension randomly performed three experimental sessions: (i) a non-exercise control session that involved 30 min of seated rest, (ii) whole body RE leading to failure that involved three sets with an eight repetitions maximum (8RM) load and (iii) whole body RE not to failure that involved three sets with 70% of an 8RM load. Systolic BP (SBP), diastolic BP (DBP) and mean BP (MBP) responses during each hour of sleep and awake states were measured. Results of all subjects revealed that the RPP was higher (P ≤ 0.05) during afternoon and night hours after the RE session leading to failure versus not to failure and the non-exercise control session. For the hypertensive group during the night hours, SBP remained higher after the RE session not to failure (P = 0.047) versus non-exercise control session. For the normotensive group, DBP remained higher after the RE session leading to failure over the 24-h period (approximately 8 mmHg h(-1), P = 0.044) and the period upon awaking (approximately 5 mmHg h(-1), P = 0.044) versus the hypertensive group. The normotensive elderly women of this pilot study presented a greater cardiovascular response to RE leading to failure, as a consequence of the higher training intensity. © 2014 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  19. Evaluation of anticipatory signal to steam generator pressure control program for 700 MWe Indian pressurized heavy water reactor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pahari, S.; Hajela, S.; Rammohan, H. P.

    2012-07-01

    700 MWe Indian Pressurized Heavy Water Reactor (IPHWR) is horizontal channel type reactor with partial boiling at channel outlet. Due to boiling, it has a large volume of vapor present in the primary loops. It has two primary loops connected with the help of pressurizer surge line. The pressurizer has a large capacity and is partly filled by liquid and partly by vapor. Large vapor volume improves compressibility of the system. During turbine trip or load rejection, pressure builds up in Steam Generator (SG). This leads to pressurization of Primary Heat Transport System (PHTS). To control pressurization of SG andmore » PHTS, around 70% of the steam generated in SG is dumped into the condenser by opening Condenser Steam Dump Valves (CSDVs) and rest of the steam is released to the atmosphere by opening Atmospheric Steam Discharge Valves (ASDVs) immediately after sensing the event. This is accomplished by adding anticipatory signal to the output of SG pressure controller. Anticipatory signal is proportional to the thermal power of reactor and the proportionality constant is set so that SG pressure controller's output jacks up to ASDV opening range when operating at 100% FP. To simulate this behavior for 700 MWe IPHWR, Primary and secondary heat transport system is modeled. SG pressure control and other process control program have also been modeled to capture overall plant dynamics. Analysis has been carried out with 3-D neutron kinetics coupled thermal hydraulic computer code ATMIKA.T to evaluate the effect of the anticipatory signal on PHT pressure and over all plant dynamics during turbine trip in 700 MWe IPHWR. This paper brings out the results of the analysis with and without considering anticipatory signal in SG pressure control program during turbine trip. (authors)« less

  20. Aircraft control surface failure detection and isolation using the OSGLR test. [orthogonal series generalized likelihood ratio

    NASA Technical Reports Server (NTRS)

    Bonnice, W. F.; Motyka, P.; Wagner, E.; Hall, S. R.

    1986-01-01

    The performance of the orthogonal series generalized likelihood ratio (OSGLR) test in detecting and isolating commercial aircraft control surface and actuator failures is evaluated. A modification to incorporate age-weighting which significantly reduces the sensitivity of the algorithm to modeling errors is presented. The steady-state implementation of the algorithm based on a single linear model valid for a cruise flight condition is tested using a nonlinear aircraft simulation. A number of off-nominal no-failure flight conditions including maneuvers, nonzero flap deflections, different turbulence levels and steady winds were tested. Based on the no-failure decision functions produced by off-nominal flight conditions, the failure detection and isolation performance at the nominal flight condition was determined. The extension of the algorithm to a wider flight envelope by scheduling on dynamic pressure and flap deflection is examined. Based on this testing, the OSGLR algorithm should be capable of detecting control surface failures that would affect the safe operation of a commercial aircraft. Isolation may be difficult if there are several surfaces which produce similar effects on the aircraft. Extending the algorithm over the entire operating envelope of a commercial aircraft appears feasible.

  1. Evaluation of monkey intraocular pressure by rebound tonometer

    PubMed Central

    Yu, Wenhan; Cao, Guiqun; Qiu, Jinghua; Ma, Jia; Li, Ni; Yu, Man; Yan, Naihong; Chen, Lei; Pang, Iok-Hou

    2009-01-01

    Purpose To evaluate the usefulness of the TonoVet™ rebound tonometer in measuring intraocular pressure (IOP) of monkeys. Methods The accuracy of the TonoVet™ rebound tonometer was determined in cannulated eyes of anesthetized rhesus monkeys where IOP was controlled by adjusting the height of a connected perfusate reservoir. To assess the applicability of the equipment through in vivo studies, the diurnal fluctuation of IOP and effects of IOP-lowering compounds were evaluated in monkeys. Results IOP readings generated by the TonoVet™ tonometer correlated very well with the actual pressure in the cannulated monkey eye. The linear correlation had a slope of 0.922±0.014 (mean±SEM, n=4), a y-intercept of 3.04±0.61, and a correlation coefficient of r2=0.97. Using this method, diurnal IOP fluctuation of the rhesus monkey was demonstrated. The tonometer was also able to detect IOP changes induced by pharmacologically active compounds. A single topical ocular instillation (15 μg) of the rho kinase inhibitor, H1152, produced a 5–6 mmHg reduction (p<0.001) in IOP, lasting at least 4 h. In addition, topical administration of Travatan®, a prostaglandin agonist, induced a small transient IOP increase (1.1 mmHg versus vehicle control; p=0.26) at 2 h after treatment followed by a pressure reduction at 23 h (−2.4 mmHg; p<0.05). Multiple daily dosing with the drug produced a persistent IOP-lowering effect. Three consecutive days of Travatan treatment produced ocular hypotension of −2.0 to −2.2 mmHg (p<0.05) the following day. Conclusions The rebound tonometer was easy to use and accurately measured IOP in the rhesus monkey eye. PMID:19898690

  2. Acute Heart Failure Triggered by Coronary Spasm With Transient Left Ventricular Dysfunction.

    PubMed

    Adachi, Yusuke; Sakakura, Kenichi; Ibe, Tatsuro; Yoshida, Nanae; Wada, Hiroshi; Fujita, Hideo; Momomura, Shin-Ichi

    2017-04-06

    Coronary spasm is abnormal contraction of an epicardial coronary artery resulting in myocardial ischemia. Coronary spasm induces not only depressed myocardial contractility, but also incomplete myocardial relaxation, which leads to elevated ventricular filling pressure. We herein report the case of a 55-year-old woman who had repeated acute heart failure caused by coronary spasm. Acetylcholine provocation test with simultaneous right heart catheterization was useful for the diagnosis of elevated ventricular filling pressure as well as coronary artery spasm. We should add coronary spasm to a differential diagnosis for repeated acute heart failure.

  3. Analysis of flexural strength and contact pressure after simulated chairside adjustment of pressed lithium disilicate glass-ceramic.

    PubMed

    Ramadhan, Ali; Thompson, Geoffrey A; Maroulakos, Georgios; Berzins, David

    2018-04-30

    Research evaluating load-to-failure of pressed lithium disilicate glass-ceramic (LDGC) with a clinically validated test after adjustment and repair procedures is scarce. The purpose of this in vitro study was to investigate the effect of the simulated chairside adjustment of the intaglio surface of monolithic pressed LDGC and procedures intended to repair damage. A total of 423 IPS e.max Press (Ivoclar Vivadent AG) disks (15 mm diameter, 1 mm height) were used in the study. The material was tested by using an equibiaxial loading arrangement (n≥30/group) and a contact pressure test (n≥20/group). Specimens were assigned to 1 of 14 groups. One-half was assigned to the equibiaxial load test and the other half underwent contact pressure testing. Testing was performed in 2 parts, before glazing and after glazing. Before-glazing specimens were devested and entered in the test protocol, while after-glazing specimens were devested and glazed before entering the test protocol. Equibiaxial flexure test specimens were placed on a ring-on-ring apparatus and loaded until failure. Contact pressure specimens were cemented to epoxy resin blocks with a resin cement and loaded with a 50-mm diameter hemisphere until failure. Tests were performed on a universal testing machine with a crosshead speed of 0.5 mm/min. Weibull statistics and likelihood ratio contour plots determined intergroup differences (95% confidence bounds). Before glazing, the equibiaxial flexural strength test and the Weibull and likelihood ratio contour plots demonstrated a significantly higher failure strength for 1EC (188 MPa) than that of the damaged and/or repaired groups. Glazing following diamond-adjustment (1EGG) was the most beneficial post-damage procedure (176 MPa). Regarding the contact pressure test, the Weibull and likelihood ratio contour plots revealed no significant difference between the 1PC (98 MPa) and 1PGG (98 MPa) groups. Diamond-adjustment, without glazing (1EG and 1PG), resulted in the

  4. Development of an adaptive failure detection and identification system for detecting aircraft control element failures

    NASA Technical Reports Server (NTRS)

    Bundick, W. Thomas

    1990-01-01

    A methodology for designing a failure detection and identification (FDI) system to detect and isolate control element failures in aircraft control systems is reviewed. An FDI system design for a modified B-737 aircraft resulting from this methodology is also reviewed, and the results of evaluating this system via simulation are presented. The FDI system performed well in a no-turbulence environment, but it experienced an unacceptable number of false alarms in atmospheric turbulence. An adaptive FDI system, which adjusts thresholds and other system parameters based on the estimated turbulence level, was developed and evaluated. The adaptive system performed well over all turbulence levels simulated, reliably detecting all but the smallest magnitude partially-missing-surface failures.

  5. Energy evolution mechanism in process of Sandstone failure and energy strength criterion

    NASA Astrophysics Data System (ADS)

    Wang, Yunfei; Cui, Fang

    2018-07-01

    To reveal the inherent relation between energy change and confining pressure during the process of sandstone damage, and its characteristics of energy storage and energy dissipation in different deformation stage. Obtaining the mechanical parameters by testing the Sandstone of two1 coal seam roof under uniaxial compression in Zhaogu coalmine, using Particle Flow Code (PFC) and fish program to get the meso-mechanical parameters, studying Sandstone energy evolution mechanism under different confining pressures, and deducing energy strength criterion based on energy principle of rock failure, some main researching results are reached as follows: with the increasing of confining pressure, the Sandstone yield stage and ductility increases, but brittleness decreases; Under higher confining pressure, the elastic strain energy of Sandstone before peak approximately keeps constant in a certain strain range, and rock absorbs all the energy which converts into surface energy required for internal damage development; Under lower confining pressure, Sandstone no longer absorbs energy with increasing strain after peak under lower confining pressure, while it sequentially absorbs energy under higher confining pressure; Under lower confining pressure, the energy Sandstone before peak absorbed mainly converts into elastic strain energy, while under higher confining pressure, dissipation energy significantly increases before peak, which indicates that the degree rock strength loss is higher under higher confining pressure; with the increasing of confining pressure, the limit of elastic strain energy increases and there exists a favourable linear variation relationship; At the peak point, the ratio of elastic strain energy to total energy of Sandstone nonlinearly decreases, while the ratio of dissipation energy to total energy nonlinearly increases with the increasing of confining pressure; According to energy evolution mechanism of rock failure, an energy strength criterion is

  6. Clinical and pathological analysis of IgA nephropathy with chronic renal failure.

    PubMed

    Liu, Yuyuan; Hu, Qinfeng; Shen, Ping; Tang, Li; Yuan, Gang; Zhou, Yongmei; Chai, Huaqi

    2016-10-01

    To investigative clinical and pathological characteristics of IgA nephropathy with chronic renal failure. Clinical and pathological findings from 65 cases of IgA nephropathy with chronic renal failure were reviewed. Pathological characteristics of all the cases were analyzed according to WHO definition and Oxford Classification. Evaluating the severity of pathological lesions by the Katafuchi R semiquantitative scoring system, and analyzing their relationship with clinical indexes of renal function. Of all 65 cases the male and female ratio was 1.4, and the mean age was 37 ± 13 years old. Levels of systolic pressure, mean arterial pressure (MAP), blood urea nitrogen (BUN), serum creatinine (Scr), uric acid (UA), album (Alb), serum IgG and 24 h urinary protein were related with eGRF level (p < 0.05, respectively). The most common pathological type was proliferative sclerosis glomerulonephritis (PSGN) and M1S1E0T0 according to WHO definition and Oxford Classification, respectively, and most of the 65 cases had glomerulosclerosis. Simple IgA deposition was the most common immunopathologic type. Of all the cases, 44.6% accompanied with C3 while 4.6% with C1q. Further analysis revealed there were no relationships between severity of pathological lesion and levels of clinical indexes (Scr and eGRF) (p > 0.05). IgA nephropathy with chronic renal failure usually occurred in young adults, and it had severe clinical condition and pathological changes, while there was no significant relationship between them.

  7. Characteristics of patients with severe heart failure exhibiting exercise oscillatory ventilation.

    PubMed

    Matsuki, Ryosuke; Kisaka, Tomohiko; Ozono, Ryoji; Kinoshita, Hiroki; Sada, Yoshiharu; Oda, Noboru; Hidaka, Takayuki; Tashiro, Naonori; Takahashi, Makoto; Sekikawa, Kiyokazu; Ito, Yoshihiro; Kimura, Hiroaki; Hamada, Hironobu; Kihara, Yasuki

    2013-01-01

    This study aims to elucidate the characteristics of patients with severe nonischemic heart failure exhibiting exercise oscillatory ventilation (EOV) and the association of these characteristics with the subjective dyspnea. Forty-six patients with nonischemic heart failure who were classified into the New York Heart Association (NYHA) functional class III underwent cardiopulmonary exercise testing (CPX) and were divided into two groups according to the presence or absence of EOV. We evaluated the patients by using the Specific Activity Scale (SAS), biochemical examination, echocardiographic evaluation, results of CPX and symptoms during CPX (Borg scale), and reasons for exercise termination. EOV was observed in 20 of 46 patients. The following characteristics were observed in patients with EOV as compared with those without EOV with statistically significant differences: more patients complaining dyspnea as the reason for exercise termination, lower SAS score, higher N-terminal pro-brain natriuretic peptide level, larger left atrial dimension and volume, left ventricular end-diastolic volume, higher Borg scale score at rest and at the anerobic threshold, higher respiratory rate at rest and at peak exercise, and higher slope of the minute ventilation-to-CO₂ output ratio, and lower end-tidal CO₂ pressure at peak exercise. Among the subjects with NYHA III nonischemic heart failure, more patients with EOV had a stronger feeling of dyspnea during exercise as compared with those without EOV, and the subjective dyspnea was an exercise-limiting factor in many cases.

  8. Fiber-optic interferometric sensors for measurements of pressure fluctuations: Experimental evaluation

    NASA Technical Reports Server (NTRS)

    Cho, Y. C.; Soderman, P. T.

    1993-01-01

    This paper addresses an anechoic chamber evaluation of a fiber-optic interferometric sensor (fiber-optic microphone), which is being developed at NASA Ames Research Center for measurements of pressure fluctuations in wind tunnels.

  9. Zebrafish Heart Failure Models for the Evaluation of Chemical Probes and Drugs

    PubMed Central

    Monte, Aaron; Cook, James M.; Kabir, Mohd Shahjahan; Peterson, Karl P.

    2013-01-01

    Abstract Heart failure is a complex disease that involves genetic, environmental, and physiological factors. As a result, current medication and treatment for heart failure produces limited efficacy, and better medication is in demand. Although mammalian models exist, simple and low-cost models will be more beneficial for drug discovery and mechanistic studies of heart failure. We previously reported that aristolochic acid (AA) caused cardiac defects in zebrafish embryos that resemble heart failure. Here, we showed that cardiac troponin T and atrial natriuretic peptide were expressed at significantly higher levels in AA-treated embryos, presumably due to cardiac hypertrophy. In addition, several human heart failure drugs could moderately attenuate the AA-induced heart failure by 10%–40%, further verifying the model for drug discovery. We then developed a drug screening assay using the AA-treated zebrafish embryos and identified three compounds. Mitogen-activated protein kinase kinase inhibitor (MEK-I), an inhibitor for the MEK-1/2 known to be involved in cardiac hypertrophy and heart failure, showed nearly 60% heart failure attenuation. C25, a chalcone derivative, and A11, a phenolic compound, showed around 80% and 90% attenuation, respectively. Time course experiments revealed that, to obtain 50% efficacy, these compounds were required within different hours of AA treatment. Furthermore, quantitative polymerase chain reaction showed that C25, not MEK-I or A11, strongly suppressed inflammation. Finally, C25 and MEK-I, but not A11, could also rescue the doxorubicin-induced heart failure in zebrafish embryos. In summary, we have established two tractable heart failure models for drug discovery and three potential drugs have been identified that seem to attenuate heart failure by different mechanisms. PMID:24351044

  10. Blood pressure evaluation using sphygmomanometry assisted by arterial pulse waveform detection by fiber Bragg grating pulse device

    NASA Astrophysics Data System (ADS)

    Sharath, Umesh; Sukreet, Raju; Apoorva, Girish; Asokan, Sundarrajan

    2013-06-01

    We report a blood pressure evaluation methodology by recording the radial arterial pulse waveform in real time using a fiber Bragg grating pulse device (FBGPD). Here, the pressure responses of the arterial pulse in the form of beat-to-beat pulse amplitude and arterial diametrical variations are monitored. Particularly, the unique signatures of pulse pressure variations have been recorded in the arterial pulse waveform, which indicate the systolic and diastolic blood pressure while the patient is subjected to the sphygmomanometric blood pressure examination. The proposed method of blood pressure evaluation using FBGPD has been validated with the auscultatory method of detecting the acoustic pulses (Korotkoff sounds) by an electronic stethoscope.

  11. Evaluating skeletal muscle electromechanical delay with intramuscular pressure.

    PubMed

    Go, Shanette A; Litchy, William J; Evertz, Loribeth Q; Kaufman, Kenton R

    2018-06-08

    Intramuscular pressure (IMP) is the fluid pressure generated within skeletal muscle and directly reflects individual muscle tension. The purpose of this study was to assess the development of force, IMP, and electromyography (EMG) in the tibialis anterior (TA) muscle during ramped isometric contractions and evaluate electromechanical delay (EMD). Force, EMG, and IMP were simultaneously measured during ramped isometric contractions in eight young, healthy human subjects. The EMD between the onset of force and EMG activity (Δt-EMG force) and the onset of IMP and EMG activity (Δt EMG-IMP) were calculated. A statistically significant difference (p < 0.05) was found between the mean force-EMG EMD (36 ± 31 ms) and the mean IMP-EMG EMD (3 ± 21 ms). IMP reflects changes in muscle tension due to the contractile muscle elements. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. The less familiar side of heart failure: symptomatic diastolic dysfunction.

    PubMed

    Morris, Spencer A; Van Swol, Mark; Udani, Bela

    2005-06-01

    Arrange for echocardiography or radionuclide angiography within 72 hours of a heart failure exacerbation. An ejection fraction >50% in the presence of signs and symptoms of heart failure makes the diagnosis of diastolic heart failure probable. To treat associated hypertension, use angiotensin receptor blockers (ARBs), angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, calcium channel blockers, or diuretics to achieve a blood pressure goal of <130/80 mm Hg. When using beta-blockers to control heart rate, titrate doses more aggressively than would be done for systolic failure, to reach a goal of 60 to 70 bpm. Use ACE inhibitors/ARBs to decrease hospitalizations, decrease symptoms, and prevent left ventricular remodeling.

  13. Evaluation of Procedures for Backcalculation of Airfield Pavement Moduli

    DTIC Science & Technology

    2015-08-01

    to develop pavement design and structural evaluation criteria, procedures, and software to ensure that its airfield pavements can support mission...aircraft. As tire pressures and aircraft weights have increased steadily during this time, the design and evaluation software– Pavement -Transportation...the remaining life for the pavement in terms of remaining pavement life (passes-to-failure) or allowable gross aircraft loads and also to design

  14. Evaluation of the Stress Adjustment and Adaptation Model among Families Reporting Economic Pressure

    ERIC Educational Resources Information Center

    Vandsburger, Etty; Biggerstaff, Marilyn A.

    2004-01-01

    This research evaluates the Stress Adjustment and Adaptation Model (double ABCX model) examining the effects resiliency resources on family functioning when families experience economic pressure. Families (N = 128) with incomes at or below the poverty line from a rural area of a southern state completed measures of perceived economic pressure,…

  15. Four hundred meters walking test in the evaluation of heart failure patients.

    PubMed

    Zdrenghea, D; Beudean, Maria; Pop, Dana; Zdrenghea, V

    2010-01-01

    The best evaluation of the severity and prognosis of heart failure patients is obtained by the maximal exercise stress testing, but for the very large number of HF patients and for evaluation of their daily effort capacity submaximal stress testing, mainly 6 minutes walking test are used. The limit of 6mWT is that during it the patients are not motivated to walk and also, the periphery, so important for heart failure patients, is not equally involved. To compare a new fixed walking test-400m walking test with 6MWT and maximal exercise testing. There were investigated 20 patients with dilated cardiomyopathy (DCM). The patients were included in the study after the relief of the congestive syndrome. Each patient was submitted in three consecutive days to a maximal symptom-limited exercise stress test on cycloergometer, a six minutes walking test, a 400 meters walking test. The last one consisted of walking on a corridor 40 meters long, at a speed chosen by the patient himself. The results were expressed in seconds representing the necessary time to cover the established 400 meters of distance. During cycloergometer exercise stress test the calculated mean peak VO2 was 15.2 +/- 1.4 mlO2/kg/min (4.32 METs). The mean distance walked during 6MWT was 350 +/- 34m and the mean time needed to walk 400m (400mWT) was 300 +/- 27 seconds. The correlation between peak VO2 and distance walked during 6MWT was -0.40, a similar but negative value (r = -0.42) being registered between peak VO2 and time registered during 400mWT. Only weak correlation was registered between LVEF and all the three tests. In turn the correlation between distance registered during 6MWT and time registered during 400mWT was excellent: r = -0.60. 400mWT is a useful tool for the evaluation of submaximal effort capacity of CHF patients. Its value to evaluate exercise capacity is similar with that of the 6 MWT, but 400mWT can assure a better evaluation of peripheral involvement.

  16. Failure rates of mini-implants placed in the infrazygomatic region.

    PubMed

    Uribe, Flavio; Mehr, Rana; Mathur, Ajay; Janakiraman, Nandakumar; Allareddy, Veerasathpurush

    2015-01-01

    The purpose of this pilot study was to evaluate the failure rates of mini-implants placed in the infrazygomatic region and to evaluate factors that affect their stability. A retrospective cohort study of 30 consecutive patients (55 mini-implants) who had infrazygomatic mini-implants at a University Clinic were evaluated for failure rates. Patient, mini-implant, orthodontic, surgical, and mini-implant maintenance factors were evaluated by univariate logistic regression models for association to failure rates. A 21.8 % failure rate of mini-implants placed in the infazygomatic region was observed. None of the predictor variables were significantly associated with higher or lower odds for failed implants. Failure rates for infrazygomatic mini-implants were slightly higher than those reported in other maxilla-mandibular osseous locations. No predictor variables were found to be associated to the failure rates.

  17. Blood Pressure Control

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Engineering Development Lab., Inc.'s E-2000 Neck Baro Reflex System was developed for cardiovascular studies of astronauts. It is regularly used on Space Shuttle Missions, and a parallel version has been developed as a research tool to facilitate studies of blood pressure reflex controls in patients with congestive heart failure, diabetes, etc. An advanced version, the PPC-1000, was developed in 1991, and the technology has been refined substantially. The PPC provides an accurate means of generating pressure for a broad array of laboratory applications. An improved version, the E2010 Barosystem, is anticipated.

  18. Visit-to-visit variability of blood pressure and coronary heart disease, stroke, heart failure and mortality: A cohort study

    PubMed Central

    Muntner, Paul; Whittle, Jeff; Lynch, Amy I.; Colantonio, Lisandro D.; Simpson, Lara M.; Einhorn, Paula T.; Levitan, Emily B.; Whelton, Paul K; Cushman, William C.; Louis, Gail T.; Davis, Barry R.; Oparil, Suzanne

    2016-01-01

    Background Variability of blood pressure (BP) across outpatient visits is frequently dismissed as random fluctuation around a patient’s underlying BP. Objective: Examine the association between visit-to-visit variability (VVV) of systolic and diastolic BP (SBP and DBP) on cardiovascular disease and mortality outcomes. Design Prospective cohort study Setting Post-hoc analysis of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). Participants 25,814 ALLHAT participants. Measurements VVV of SBP was defined as the standard deviation (SD) across BP measurements obtained at 7 visits conducted from 6 to 28 months following ALLHAT enrollment. Participants free of cardiovascular disease events during the first 28 months of follow-up were followed from the month 28 study visit through the end of active ALLHAT follow-up. Outcomes included fatal coronary heart disease or non-fatal myocardial infarction, all-cause mortality, stroke and heart failure. Results There were 1194 cases of fatal CHD or non-fatal MI, 1948 deaths, 606 cases of stroke and 921 cases of heart failure during follow-up. After multivariable adjustment including mean SBP, the hazard ratio comparing participants in the highest versus lowest quintile of SD of SBP (≥14.4 mmHg versus <6.5 mmHg) was 1.30 (1.06–1.59) for fatal coronary heart disease or non-fatal myocardial infarction, 1.58 (1.32–1.90) for all-cause mortality, 1.46 (1.06–2.01) for stroke, and 1.25 (0.97–1.61) for heart failure. Higher VVV of DBP was also associated with cardiovascular disease events and mortality. Limitations Long-term outcomes were not available. Conclusions Higher VVV of SBP is associated with increased cardiovascular disease and mortality risk. Future studies should examine whether reducing VVV of BP lowers this risk. Primary funding source National Institutes of Health PMID:26215765

  19. Comparison of Comfort and Effectiveness of Total Face Mask and Oronasal Mask in Noninvasive Positive Pressure Ventilation in Patients with Acute Respiratory Failure: A Clinical Trial.

    PubMed

    Sadeghi, Somayeh; Fakharian, Atefeh; Nasri, Peiman; Kiani, Arda

    2017-01-01

    Background . There is a growing controversy about the use of oronasal masks (ONM) or total facemask (TFM) in noninvasive positive pressure ventilation (NPPV), so we designed a trial to compare the uses of these two masks in terms of effectiveness and comfort. Methods . Between February and November 2014, a total of 48 patients with respiratory failure were studied. Patients were randomized to receive NPPV via ONM or TFM. Data were recorded at 60 minutes and six and 24 hours after intervention. Patient comfort was assessed using a questionnaire. Data were analyzed using t -test and chi-square test. Repeated measures ANOVA and Mann-Whitney U test were used to compare clinical and laboratory data. Results . There were no differences in venous blood gas (VBG) values between the two groups ( P > 0.05). However, at six hours, TFM was much more effective in reducing the partial pressure of carbon dioxide (PCO2) ( P = 0.04). Patient comfort and acceptance were statistically similar in both groups ( P > 0.05). Total time of NPPV was also similar in the two groups ( P > 0.05). Conclusions . TFM was superior to ONM in acute phase of respiratory failure but not once the patients were out of acute phase.

  20. Hemodynamic changes during weaning: can we assess and predict cardiac-related weaning failure by transthoracic echocardiography?

    PubMed Central

    2010-01-01

    Cardiac-related failure of weaning from mechanical ventilation is an important reason for prolonged mechanical ventilation, intensive care unit treatment, and increased morbidity and mortality. When transthoracic echocardiography (TTE) is routinely performed before a weaning trial, patients at high risk of cardiac-related failure can be detected by low left ventricular (LV) ejection fraction, diastolic dysfunction, and elevated LV filling pressure. During the weaning trial, a further increase of LV filling pressure and progression of diastolic failure can be observed by repeated TTE. Owing to certain limitations concerning patients and methodology, TTE cannot be employed in every patient and invasive hemodynamic monitoring is still mandatory in selected patients with repetitive weaning failure. PMID:20619005

  1. Hemodynamic changes during weaning: can we assess and predict cardiac-related weaning failure by transthoracic echocardiography?

    PubMed

    Voga, Gorazd

    2010-01-01

    Cardiac-related failure of weaning from mechanical ventilation is an important reason for prolonged mechanical ventilation, intensive care unit treatment, and increased morbidity and mortality. When transthoracic echocardiography (TTE) is routinely performed before a weaning trial, patients at high risk of cardiac-related failure can be detected by low left ventricular (LV) ejection fraction, diastolic dysfunction, and elevated LV filling pressure. During the weaning trial, a further increase of LV filling pressure and progression of diastolic failure can be observed by repeated TTE. Owing to certain limitations concerning patients and methodology, TTE cannot be employed in every patient and invasive hemodynamic monitoring is still mandatory in selected patients with repetitive weaning failure.

  2. Improving Patient Outcomes With Oral Heart Failure Medications.

    PubMed

    Sherrod, Melissa M; Cheek, Dennis J; Seale, Ashlie

    2016-05-01

    Hospitals are under immense pressure to reduce heart failure readmissions that occur within 30 days of discharge, and to improve the quality of care for these patients. Penalties mandated by the Affordable Care Act decrease hospital reimbursement and ultimately the overall cost of caring for these patients increases if they are not well managed. Approximately 25% of patients hospitalized for heart failure are at high risk for readmission and these rates have not changed over the past decade. As a result of an aging population, the incidence of heart failure is expected to increase to one in five Americans over the age of 65. Pharmacologic management can reduce the risk of death and help prevent unnecessary hospitalizations. Healthcare providers who have knowledge of heart failure medications and drug interactions and share this information with their patients contribute to improved long-term survival and physical functioning as well as fewer hospitalizations and a delay of progressive worsening of heart failure.

  3. Assessment of Intralaminar Progressive Damage and Failure Analysis Using an Efficient Evaluation Framework

    NASA Technical Reports Server (NTRS)

    Hyder, Imran; Schaefer, Joseph; Justusson, Brian; Wanthal, Steve; Leone, Frank; Rose, Cheryl

    2017-01-01

    Reducing the timeline for development and certification for composite structures has been a long standing objective of the aerospace industry. This timeline can be further exacerbated when attempting to integrate new fiber-reinforced composite materials due to the large number of testing required at every level of design. computational progressive damage and failure analysis (PDFA) attempts to mitigate this effect; however, new PDFA methods have been slow to be adopted in industry since material model evaluation techniques have not been fully defined. This study presents an efficient evaluation framework which uses a piecewise verification and validation (V&V) approach for PDFA methods. Specifically, the framework is applied to evaluate PDFA research codes within the context of intralaminar damage. Methods are incrementally taken through various V&V exercises specifically tailored to study PDFA intralaminar damage modeling capability. Finally, methods are evaluated against a defined set of success criteria to highlight successes and limitations.

  4. Cost-Effectiveness Analysis of Plasma Versus Recombinant Factor VIIa for Placing Intracranial Pressure Monitors in Pretransplant Patients With Acute Liver Failure.

    PubMed

    Pham, Huy P; Sireci, Anthony N; Kim, Chong H; Schwartz, Joseph

    2014-09-01

    Both plasma- and recombinant activated factor VII (rFVIIa)-based algorithms can be used to correct coagulopathy in preliver transplant patients with acute liver failure requiring intracranial pressure monitor (ICPM) placement. A decision model was created to compare the cost-effectiveness of these methods. A 70-kg patient could receive either 1 round of plasma followed by coagulation testing or 2 units of plasma and 40 μg/kg rFVIIa. Intracranial pressure monitor is placed without coagulation testing after rFVIIa administration. In the plasma algorithm, the probability of ICPM placement was estimated based on expected international normalized ratio (INR) after plasma administration. Risks of rFVIIa thrombosis and transfusion reactions were also included. The model was run for patients with INRs ranging from 2 to 6 with concomitant adjustments to model parameters. The model supported the initial use of rFVIIa for ICPM placement as a cost-effective treatment when INR ≥2 (with incremental cost-effectiveness ratio of at most US$7088.02). © The Author(s) 2014.

  5. Independent Orbiter Assessment (IOA): Analysis of the atmospheric revitalization pressure control subsystem

    NASA Technical Reports Server (NTRS)

    Saiidi, M. J.; Duffy, R. E.; Mclaughlin, T. D.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis/Critical Items List (FMEA/CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Atmospheric Revitalization and Pressure Control Subsystem (ARPCS) are documented. The ARPCS hardware was categorized into the following subdivisions: (1) Atmospheric Make-up and Control (including the Auxiliary Oxygen Assembly, Oxygen Assembly, and Nitrogen Assembly); and (2) Atmospheric Vent and Control (including the Positive Relief Vent Assembly, Negative Relief Vent Assembly, and Cabin Vent Assembly). The IOA analysis process utilized available ARPCS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

  6. Urocortin-2 infusion in acute decompensated heart failure: findings from the UNICORN study (urocortin-2 in the treatment of acute heart failure as an adjunct over conventional therapy).

    PubMed

    Chan, W Y Wandy; Frampton, Christopher M; Crozier, Ian G; Troughton, Richard W; Richards, A Mark

    2013-10-01

    The purpose of this study is to investigate the effects of urocortin-2 as adjunct therapy in acute decompensated heart failure (ADHF). Urocortin-2 produced favorable integrated effects in experimental heart failure but there are no equivalent human data. We describe the first therapeutic study of urocortin-2 infusion in ADHF. Fifty-three patients with ADHF were randomly assigned to 5 ng/kg/min of urocortin-2 or placebo infusion for 4 h as an adjunct therapy. Changes in vital signs, plasma neurohormonal and renal indices during treatment were compared using repeated-measures analysis of covariance. Ten patients in each arm underwent more detailed invasive hemodynamic evaluation. Urocortin-2 produced greater falls in systolic blood pressure compared to placebo (16 ± 5.8 mm Hg, p < 0.001) with nonsignificant increases in heart rate (5.7 ± 3.8 beats/min, p = 0.07) and increased cardiac output (2.1 ± 0.4 l/min vs. -0.1 ± 0.4 l/min, p < 0.001) associated with a 47% reduction in calculated total peripheral resistance (p = 0.015). Falls in pulmonary artery and pulmonary capillary wedge pressures did not differ significantly between groups. Urocortin-2 reduced urine volume and creatinine clearance during infusion but these returned to above baseline level in the 8 h after infusion. Plasma renin activity rose briefly with urocortin-2 coinciding with reductions in blood pressure (p < 0.001). B-type natriuretic peptide levels fell significantly over 24 h with urocortin-2 (p < 0.01) but not with placebo. Urocortin-2 infusion in ADHF markedly augmented cardiac output without significant reflex tachycardia. Renal indices fell transiently concurrent with urocortin-2-induced reductions in blood pressure. Further investigations are required to uncover the full potential of urocortin-2 in treating ADHF. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  7. Decreased brain sigma-1 receptor contributes to the relationship between heart failure and depression.

    PubMed

    Ito, Koji; Hirooka, Yoshitaka; Matsukawa, Ryuichi; Nakano, Masatsugu; Sunagawa, Kenji

    2012-01-01

    Depression often coexists with cardiovascular disease, such as hypertension and heart failure, in which sympathetic hyperactivation is critically involved. Reduction in the brain sigma-1 receptor (S1R) functions in depression pathogenesis via neuronal activity modulation. We hypothesized that reduced brain S1R exacerbates heart failure, especially with pressure overload via sympathetic hyperactivation and worsening depression. Male Institute of Cancer Research mice were treated with aortic banding and, 4 weeks thereafter, fed a high-salt diet for an additional 4 weeks to accelerate cardiac dysfunction (AB-H). Compared with sham-operated controls (Sham), AB-H showed augmented sympathetic activity, decreased per cent fractional shortening, increased left ventricular dimensions, and significantly lower brain S1R expression. Intracerebroventricular (ICV) infusion of S1R agonist PRE084 increased brain S1R expression, lowered sympathetic activity, and improved cardiac function in AB-H. ICV infusion of S1R antagonist BD1063 increased sympathetic activity and decreased cardiac function in Sham. Tail suspension test was used to evaluate the index of depression-like behaviour, with immobility time and strain amplitude recorded as markers of struggle activity using a force transducer. Immobility time increased and strain amplitude decreased in AB-H compared with Sham, and these changes were attenuated by ICV infusion of PRE084. These results indicate that decreased brain S1R contributes to the relationship between heart failure and depression in a mouse model of pressure overload.

  8. 14 CFR 23.365 - Pressurized cabin loads.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... stress concentrations, must be accounted for. (c) If landings may be made with the cabin pressurized... be designed for the effects of sudden release of pressure in any compartment with external doors or windows. This condition must be investigated for the effects of failure of the largest opening in the...

  9. [Pressure ulcer prevention--evaluation of awarness in families of patients at risk].

    PubMed

    Kwiczala-Szydłowska, Seweryna; Skalska, Anna; Grodzicki, Tomasz

    2005-01-01

    Widespread use of risk assessing scales and standards in health care of chronically ill patients resulted in improvement of pressure ulcer prevention and treatment in institutional care. However many bed-ridden patients depend on awareness and preparation of families and caregivers, who provide home care after discharge from the hospital. The aim of this study was to evaluate the knowledge of pressure ulcers prevention in families of patient at risk. During a 4 month period, 62 caregivers (78% family members and 22% non-related) filled out the questionnaire enquiring about the issue related to pressure ulcer prevention and treatment. Only 11% of questioned person knew what the pressure ulcer was, 42% of caregivers were not aware of possible pressure ulcer causes, and 54.8% were not able to mention any pressure ulcer risk factor. Most of caregivers did not know basic principles of prevention including devices useful in pressure ulcer prevention, did not know about pressure reducing mattresses nor dressings used in pressure ulcers treatment. Fifty three percent of questioned persons never received any information about pressure ulcer prevention, and only 23% received such information from nurses--which reflects low involvement of professional staff in education of families of patients at risk in principles of pressure ulcers prevention. Families and caregivers of bed-ridden patients have insufficient knowledge of pressure ulcer prevention. Contribution of medical staff in education of families of patients at risk in pressure ulcer prevention is minimal, indicating the need of preparation and implementation of an educational program for bed-ridden patients' caregivers.

  10. Four faces of baroreflex failure: hypertensive crisis, volatile hypertension, orthostatic tachycardia, and malignant vagotonia

    NASA Technical Reports Server (NTRS)

    Ketch, Terry; Biaggioni, Italo; Robertson, RoseMarie; Robertson, David

    2002-01-01

    BACKGROUND: The baroreflex normally serves to buffer blood pressure against excessive rise or fall. Baroreflex failure occurs when afferent baroreceptive nerves or their central connections become impaired. In baroreflex failure, there is loss of buffering ability, and wide excursions of pressure and heart rate occur. Such excursions may derive from endogenous factors such as stress or drowsiness, which result in quite high and quite low pressures, respectively. They may also derive from exogenous factors such as drugs or environmental influences. METHODS AND RESULTS: Impairment of the baroreflex may produce an unusually broad spectrum of clinical presentations; with acute baroreflex failure, a hypertensive crisis is the most common presentation. Over succeeding days to weeks, or in the absence of an acute event, volatile hypertension with periods of hypotension occurs and may continue for many years, usually with some attenuation of pressor surges and greater prominence of depressor valleys during long-term follow-up. With incomplete loss of baroreflex afferents, a mild syndrome of orthostatic tachycardia or orthostatic intolerance may appear. Finally, if the baroreflex failure occurs without concomitant destruction of the parasympathetic efferent vagal fibers, a resting state may lead to malignant vagotonia with severe bradycardia and hypotension and episodes of sinus arrest. CONCLUSIONS: Although baroreflex failure is not the most common cause of the above conditions, correct differentiation from other cardiovascular disorders is important, because therapy of baroreflex failure requires specific strategies, which may lead to successful control.

  11. Diagnostic workup, etiologies and management of acute right ventricle failure : A state-of-the-art paper.

    PubMed

    Vieillard-Baron, Antoine; Naeije, R; Haddad, F; Bogaard, H J; Bull, T M; Fletcher, N; Lahm, T; Magder, S; Orde, S; Schmidt, G; Pinsky, M R

    2018-05-09

    This is a state-of-the-art article of the diagnostic process, etiologies and management of acute right ventricular (RV) failure in critically ill patients. It is based on a large review of previously published articles in the field, as well as the expertise of the authors. The authors propose the ten key points and directions for future research in the field. RV failure (RVF) is frequent in the ICU, magnified by the frequent need for positive pressure ventilation. While no universal definition of RVF is accepted, we propose that RVF may be defined as a state in which the right ventricle is unable to meet the demands for blood flow without excessive use of the Frank-Starling mechanism (i.e. increase in stroke volume associated with increased preload). Both echocardiography and hemodynamic monitoring play a central role in the evaluation of RVF in the ICU. Management of RVF includes treatment of the causes, respiratory optimization and hemodynamic support. The administration of fluids is potentially deleterious and unlikely to lead to improvement in cardiac output in the majority of cases. Vasopressors are needed in the setting of shock to restore the systemic pressure and avoid RV ischemia; inotropic drug or inodilator therapies may also be needed. In the most severe cases, recent mechanical circulatory support devices are proposed to unload the RV and improve organ perfusion CONCLUSION: RV function evaluation is key in the critically-ill patients for hemodynamic management, as fluid optimization, vasopressor strategy and respiratory support. RV failure may be diagnosed by the association of different devices and parameters, while echocardiography is crucial.

  12. Efficacy of nasal bi-level positive airway pressure in congestive heart failure patients with cheyne-stokes respiration and central sleep apnea.

    PubMed

    Kasai, Takatoshi; Narui, Koji; Dohi, Tomotaka; Ishiwata, Sugao; Yoshimura, Kunihiko; Nishiyama, Shin-Ichiro; Yamaguchi, Tetsu; Momomura, Shin-Ichi

    2005-08-01

    Cheyne - Stokes respiration with central sleep apnea (CSR-CSA) contributes to the poor prognosis in patients with congestive heart failure (CHF). Bi-level positive airway pressure (bi-level PAP) may be an effective alternative for treating CSR-CSA and CHF. Fourteen patients with CSR-CSA were divided into 2 groups, a control group that included 7 patients who decided to receive only conventional medications and a group of 7 patients that received bi-level PAP. Left ventricular ejection fraction (LVEF), mitral regurgitation (MR) area, plasma brain natriuretic peptide (BNP) concentration and the New York Heart Association (NYHA) functional class were evaluated initially (baseline) and 3 months later. In the control group, there were no significant changes in cardiac function during the study period. In contrast, in the group that received bi-level PAP, there were significant improvements in LVEF (from 36.3+/-2.9% to 46.0+/-4.0%, p = 0.02), MR area (from 30.4+/-7.6% to 20.0+/-5.1%, p = 0.02), BNP (from 993.6+/-332.0 pg/ml to 474.0+/-257.6 pg/ml, p = 0.02) and NYHA functional class (from 3.1+/-0.1 to 2.1+/-0.1, p = 0.03). Treatment with bi-level PAP improved cardiac functions in CHF patients with CSR-CSA.

  13. Design of high pressure oxygen filter for extravehicular activity life support system, volume 1

    NASA Technical Reports Server (NTRS)

    Wilson, B. A.

    1977-01-01

    The experience of the National Aeronautics and Space Administration (NASA) with extravehicular activity life support emergency oxygen supply subsystems has shown a large number of problems associated with particulate contamination. These problems have resulted in failures of high pressure oxygen component sealing surfaces. A high pressure oxygen filter was designed which would (a) control the particulate contamination level in the oxygen system to a five-micron glass bead rating, ten-micron absolute condition (b) withstand the dynamic shock condition resulting from the sudden opening of 8000 psi oxygen system shutoff valve. Results of the following program tasks are reported: (1) contaminant source identification tests, (2) dynamic system tests, (3) high pressure oxygen filter concept evaluation, (4) design, (5) fabrication, (6) test, and (7) application demonstration.

  14. Economic impact of heart failure according to the effects of kidney failure.

    PubMed

    Sicras Mainar, Antoni; Navarro Artieda, Ruth; Ibáñez Nolla, Jordi

    2015-01-01

    To evaluate the use of health care resources and their cost according to the effects of kidney failure in heart failure patients during 2-year follow-up in a population setting. Observational retrospective study based on a review of medical records. The study included patients ≥ 45 years treated for heart failure from 2008 to 2010. The patients were divided into 2 groups according to the presence/absence of KF. Main outcome variables were comorbidity, clinical status (functional class, etiology), metabolic syndrome, costs, and new cases of cardiovascular events and kidney failure. The cost model included direct and indirect health care costs. Statistical analysis included multiple regression models. The study recruited 1600 patients (prevalence, 4.0%; mean age 72.4 years; women, 59.7%). Of these patients, 70.1% had hypertension, 47.1% had dyslipidemia, and 36.2% had diabetes mellitus. We analyzed 433 patients (27.1%) with kidney failure and 1167 (72.9%) without kidney failure. Patients with kidney failure were associated with functional class III-IV (54.1% vs 40.8%) and metabolic syndrome (65.3% vs 51.9%, P<.01). The average unit cost was €10,711.40. The corrected cost in the presence of kidney failure was €14,868.20 vs €9,364.50 (P=.001). During follow-up, 11.7% patients developed ischemic heart disease, 18.8% developed kidney failure, and 36.1% developed heart failure exacerbation. Comorbidity associated with heart failure is high. The presence of kidney failure increases the use of health resources and leads to higher costs within the National Health System. Copyright © 2014 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

  15. Continuous ambulatory right heart pressure measurements with an implantable hemodynamic monitor: a multicenter, 12-month follow-up study of patients with chronic heart failure.

    PubMed

    Magalski, Anthony; Adamson, Philip; Gadler, Frederick; Böehm, Michael; Steinhaus, David; Reynolds, Dwight; Vlach, Kathryn; Linde, Cecilia; Cremers, Bodo; Sparks, Brandon; Bennett, Tom

    2002-04-01

    We describe the performance of an implantable hemodynamic monitor (IHM) that allows continuous recording of heart rate, patient activity levels, and right ventricular systolic, right ventricular diastolic, and estimated pulmonary artery diastolic pressures. Pressure parameters derived from the implantable monitor were correlated to measurements made with a balloon-tipped catheter to establish accuracy and reproducibility over time in patients with chronic heart failure (CHF). IHM devices were implanted in 32 patients with CHF (left ventricular ejection fraction, 29% +/- 11%; range, 14%-62%) and were tested with right heart catheterization at implantation and 3, 6, and 12 months later. Hemodynamic variables were digitally recorded simultaneously from the IHM and catheter. Values were recorded during supine rest, peak response of Valsalva maneuver, sitting, peak of a 2-stage (25-50 W) bicycle exercise test, and final rest period. The median of 21 paired beat-to-beat cardiac cycles was analyzed for each intervention. A total of 217 paired data values from all maneuvers were analyzed for 32 patients at implantation and 129 paired data values for 20 patients at 1 year. The IHM and catheter values were not different at baseline or at 1 year (P >.05). Combining all interventions, correlation coefficients were 0.96 and 0.94 for right ventricular systolic pressure, 0.96 and 0.83 for right ventricular diastolic pressure, and 0.87 and 0.87 for estimated pulmonary artery diastolic pressure at implantation and 1 year, respectively. The IHM and a standard reference pressure system recorded comparable right heart pressure values in patients with CHF. This implantable pressure transducer is accurate over time and provides a means to precisely monitor the hemodynamic condition of patients with CHF in a continuous fashion.

  16. Efficacy of atomoxetine versus midodrine for the treatment of orthostatic hypotension in autonomic failure.

    PubMed

    Ramirez, Claudia E; Okamoto, Luis E; Arnold, Amy C; Gamboa, Alfredo; Diedrich, André; Choi, Leena; Raj, Satish R; Robertson, David; Biaggioni, Italo; Shibao, Cyndya A

    2014-12-01

    The clinical presentation of autonomic failure is orthostatic hypotension. Severely affected patients require pharmacological treatment to prevent presyncopal symptoms or frank syncope. We previously reported in a proof of concept study that pediatric doses of the norepinephrine transporter blockade, atomoxetine, increases blood pressure in autonomic failure patients with residual sympathetic activity compared with placebo. Given that the sympathetic nervous system is maximally activated in the upright position, we hypothesized that atomoxetine would be superior to midodrine, a direct vasoconstrictor, in improving upright blood pressure and orthostatic hypotension-related symptoms. To test this hypothesis, we compared the effect of acute atomoxetine versus midodrine on upright systolic blood pressure and orthostatic symptom scores in 65 patients with severe autonomic failure. There were no differences in seated systolic blood pressure (means difference=0.3 mm Hg; 95% confidence [CI], -7.3 to 7.9; P=0.94). In contrast, atomoxetine produced a greater pressor response in upright systolic blood pressure (means difference=7.5 mm Hg; 95% CI, 0.6 to 15; P=0.03) compared with midodrine. Furthermore, atomoxetine (means difference=0.4; 95% CI, 0.1 to 0.8; P=0.02), but not midodrine (means difference=0.5; 95% CI, -0.1 to 1.0; P=0.08), improved orthostatic hypotension-related symptoms as compared with placebo. The results of our study suggest that atomoxetine could be a superior therapeutic option than midodrine for the treatment of orthostatic hypotension in autonomic failure. © 2014 American Heart Association, Inc.

  17. Evaluation of Encapsulated Liver Cell Spheroids in a Fluidised-Bed Bioartificial Liver for Treatment of Ischaemic Acute Liver Failure in Pigs in a Translational Setting

    PubMed Central

    Selden, Clare; Spearman, Catherine Wendy; Kahn, Delawir; Miller, Malcolm; Figaji, Anthony; Erro, Eloy; Bundy, James; Massie, Isobel; Chalmers, Sherri-Ann; Arendse, Hiram; Gautier, Aude; Sharratt, Peter; Fuller, Barry; Hodgson, Humphrey

    2013-01-01

    Liver failure is an increasing problem. Donor-organ shortage results in patients dying before receiving a transplant. Since the liver can regenerate, alternative therapies providing temporary liver-support are sought. A bioartificial-liver would temporarily substitute function in liver failure buying time for liver regeneration/organ-procurement. Our aim: to develop a prototype bioartificial-liver-machine (BAL) comprising a human liver-derived cell-line, cultured to phenotypic competence and deliverable in a clinical setting to sites distant from its preparation. The objective of this study was to determine whether its use would improve functional parameters of liver failure in pigs with acute liver failure, to provide proof-of-principle. HepG2cells encapsulated in alginate-beads, proliferated in a fluidised-bed-bioreactor providing a biomass of 4–6×1010cells, were transported from preparation-laboratory to point-of-use operating theatre (6000miles) under perfluorodecalin at ambient temperature. Irreversible ischaemic liver failure was induced in anaesthetised pigs, after portal-systemic-shunt, by hepatic-artery-ligation. Biochemical parameters, intracranial pressure, and functional-clotting were measured in animals connected in an extracorporeal bioartificial-liver circuit. Efficacy was demonstrated comparing outcomes between animals connected to a circuit containing alginate-encapsulated cells (Cell-bead BAL), and those connected to circuit containing alginate capsules without cells (Empty-bead BAL). Cells of the biomass met regulatory standards for sterility and provenance. All animals developed progressive liver-failure after ischaemia induction. Efficacy of BAL was demonstrated since animals connected to a functional biomass (+ cells) had significantly smaller rises in intracranial pressure, lower ammonia levels, more bilirubin conjugation, improved acidosis and clotting restoration compared to animals connected to the circuit without cells. In the +cell

  18. Comparative clinical evaluation of Boerhavia diffusa root extract with standard Enalapril treatment in Canine chronic renal failure

    PubMed Central

    Oburai, Nethaji Lokeswar; Rao, V. Vaikunta; Bonath, Ram Babu Naik

    2015-01-01

    Background: Complementing herbal drugs with conservative modern treatment could improve renal condition in canine chronic renal failure (CRF). Objective: In this study, clinical evaluation of Boerhavia diffusa root extract was carried out in CRF in dogs in comparison with standard enalapril. Materials and Methods: A total of 20 dogs of mixed breeds suffering from CRF from 1 to 2 months were divided into two groups (n = 10) and treated as follows: Group I - Enalapril at 0.5 mg/kg p.o. once daily for 90 days + amoxicillin and cloxacillin at 25 mg/kg i.m. once daily for 1-week; Group II - B. diffusa root extract at 500 mg p.o per dog daily for 90 days. Both groups were maintained on a supportive fluid therapy. The data were analyzed using paired t-test and one-way ANOVA followed by Dunnett's post-hoc test. Results: CRF caused a significant (P < 0.05) increase in systolic and diastolic blood pressure, serum creatinine, urea nitrogen, sodium, potassium, phosphorus, urinary protein, alkaline phosphatase (ALP), and glutamyl transferase (GGT). A significant (P < 0.05) decrease in hemoglobin and total erythrocyte count (TEC) was also observed. Nephrosonography revealed indistinct corticomedullary junction, altered renal architecture, hyper-echoic cortex, medulla, and sunken kidneys. Both the treatments significantly (P < 0.05) reduced systolic and diastolic blood pressure by day 30. Serum Creatinine, urea nitrogen, phosphorus, urinary protein, ALP, and GGT showed significant (P < 0.05) reduction by day 60 in both the treatments. However, potassium levels were normalized only by B. diffusa root extract treatment by day 30. Both the treatments failed to show a significant improvement in nephrosonographic picture even after 90 days posttreatment. Conclusion: In conclusion, the efficacy of B. diffusa root extract was comparable to standard enalapril treatment of CRF in dogs. PMID:26604549

  19. [Telemetric monitoring reduces visits to the emergency room and cost of care in patients with chronic heart failure].

    PubMed

    Pérez-Rodríguez, Gilberto; Brito-Zurita, Olga Rosa; Sistos-Navarro, Enrique; Benítez-Aréchiga, Zaria Margarita; Sarmiento-Salazar, Gloria Leticia; Vargas-Lizárraga, José Feliciano

    2015-01-01

    Tele-cardiology is the use of information technologies that help prolong survival, improve quality of life and reduce costs in health care. Heart failure is a chronic disease that leads to high care costs. To determine the effectiveness of telemetric monitoring for controlling clinical variables, reduced emergency room visits, and cost of care in a group of patients with heart failure compared to traditional medical consultation. A randomized, controlled and open clinical trial was conducted on 40 patients with Heart failure in a tertiary care centre in north-western Mexico. The patients were divided randomly into 2 groups of 20 patients each (telemetric monitoring, traditional medical consultation). In each participant was evaluated for: blood pressure, heart rate and body weight. The telemetric monitoring group was monitored remotely and traditional medical consultation group came to the hospital on scheduled dates. All patients could come to the emergency room if necessary. The telemetric monitoring group decreased their weight and improved control of the disease (P=.01). Systolic blood pressure and cost of care decreased (51%) significantly compared traditional medical consultation group (P>.05). Admission to the emergency room was avoided in 100% of patients in the telemetric monitoring group. In patients with heart failure, the telemetric monitoring was effective in reducing emergency room visits and saved significant resources in care during follow-up. Copyright © 2015 Academia Mexicana de Cirugía A.C. Published by Masson Doyma México S.A. All rights reserved.

  20. Evaluation of blood and serum markers in spinal cord injured patients with pressure sores.

    PubMed

    Gurcay, Eda; Bal, Ajda; Gurcay, Ahmet G; Cakci, Aytul

    2009-03-01

    To evaluate blood and serum markers in traumatic spinal cord injured (SCI) patients, with and without pressure sores. This cross-sectional study was performed at the Ministry of Health Diskapi Yildirim Beyazit, and Numune Education and Research Hospitals, Ankara, Turkey, from 2006-2008. A total of 23 SCI patients with pressure sores (group I) and a control group of 25 SCI patients without pressure sores (group II) were evaluated. Characteristics of sores were examined with respect to duration, location, grade, tissue types, surface area, and exudate amount. Recorded laboratory parameters included erythrocyte sedimentation rates (ESR), C-reactive protein (CRP), hemoglobin (Hb), hematocrit (Htc), lymphocytes, white blood cells (WBC), red blood cells (RBC), serum iron, transferrin, total iron-binding capacity (TIBC), ferritin, total protein, albumin, vitamin B12, and zinc. The most common pressure sore location was the sacrum (38%). Compared to the control group, the patients with pressure sores showed anemia with reduced serum iron, transferrin, TIBC, and increased ferritin. They also had increased ESR, CRP, and WBC and reduced lymphocytes, total protein, albumin and zinc. Statistically significant correlations were found between CRP, Hb, Htc, lymphocytes, RBC, WBC, and serum protein levels, and grade of pressure sores. Clinicians should regularly screen patients with respect to blood and serum markers, in order to determine any risks for pressure sores, and they should perform immediate preventive measures based on the patient's condition.

  1. Failure Simulation Testing of the Z-1 Spacesuit Titanium Bearing Assemblies

    NASA Technical Reports Server (NTRS)

    de Baca, Richard C.; Juarez, Alfredo; Peralta, Stephen; Tylka, Jonathan; Rhodes, Richard

    2016-01-01

    The Z-2 is a candidate for NASA's next generation spacesuit, designed for a range of possible missions with enhanced mobility for spacewalks both on planetary surfaces and in microgravity. Increased mobility was accomplished through innovations in shoulder and hip joints, using a number of new bearings to allow spacesuit wearers to dip, walk, and bend with ease; all important tasks for a planetary explorer collecting samples or traveling over rough terrain. The Advanced Spacesuit Development Team of NASA Johnson Space Center requested that the NASA White Sands Test Facility (WSTF) perform a series failure simulation tests on three titanium bearing assemblies, an elemental part of the joint construction used in new spacesuit designs. This testing simulated two undetected failures within the bearings and as a result the objective of this test program was to evaluate whether a failed or failing bearing could result in ignition of the titanium race material due to friction. The first failure was an inner seal leak sufficient to pressurize the race with +99 percent oxygen. The second failure was an improperly installed or mismatched ball port that created a protrusion in the ball bearing race, partially obstructing the nominal rolling path of each ball bearing. When the spacesuit bearings are assembled, bearing balls are loaded into the assembly via a ball port. The ball port is specific and unique to each bearing assembly (matched pair). The simulated mismatched ball port is a significant source of friction, which would be caused by an assembly error. To evaluate this risk, the bearings were cycled in a simulated worst-case scenario environment, with operational loads, and potential flaw conditions. During test the amount of actuation torque required and heat generated through continuous operation were measured and the bearings were observed for sparks or burning events. This paper provides detailed descriptions of the test hardware, methodology, and results.

  2. High definition urethral pressure profilometry: Evaluating a novel microtip catheter.

    PubMed

    Klünder, Mario; Amend, Bastian; Vaegler, Martin; Kelp, Alexandra; Feuer, Ronny; Sievert, Karl-Dietrich; Stenzl, Arnulf; Sawodny, Oliver; Ederer, Michael

    2016-11-01

    Urethral pressure profilometry (UPP) is used in the diagnosis of stress urinary incontinence (SUI). SUI is a significant medical, social, and economic problem, affecting about 12.5% of the population. A novel microtip catheter was developed for UPP featuring an inclination sensor and higher angular resolution compared to systems in clinical use today. Therewith, the location of each measured pressure sample can be determined and the spatial pressure distribution inside the urethra reconstructed. In order to assess the performance and plausibility of data from the microtip catheter, we compare it to data from a double balloon air charged system. Both catheters are used on sedated female minipigs. Data from the microtip catheter are processed through a signal reconstruction algorithm, plotted and compared against data from the air-charged catheter. The microtip catheter delivers results in agreement with previous comparisons of microtip and air-charged systems. It additionally provides a new level of detail in the reconstructed UPPs which may lead to new insights into the sphincter mechanism of minipigs. The ability of air-charged catheters to measure pressure circumferentially is widely considered a main advantage over microtip catheters. However, directional pressure readings can provide additional information on angular fluctuations in the urethral pressure distribution. It is shown that the novel microtip catheter in combination with a signal reconstruction algorithm delivers plausible data. It offers the opportunity to evaluate urethral structures, especially the sphincter, in context of the correct location within the anatomical location of the pelvic floor. Neurourol. Urodynam. 35:888-894, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  3. Probabilistic pipe fracture evaluations for leak-rate-detection applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rahman, S.; Ghadiali, N.; Paul, D.

    1995-04-01

    Regulatory Guide 1.45, {open_quotes}Reactor Coolant Pressure Boundary Leakage Detection Systems,{close_quotes} was published by the U.S. Nuclear Regulatory Commission (NRC) in May 1973, and provides guidance on leak detection methods and system requirements for Light Water Reactors. Additionally, leak detection limits are specified in plant Technical Specifications and are different for Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs). These leak detection limits are also used in leak-before-break evaluations performed in accordance with Draft Standard Review Plan, Section 3.6.3, {open_quotes}Leak Before Break Evaluation Procedures{close_quotes} where a margin of 10 on the leak detection limit is used in determining the crackmore » size considered in subsequent fracture analyses. This study was requested by the NRC to: (1) evaluate the conditional failure probability for BWR and PWR piping for pipes that were leaking at the allowable leak detection limit, and (2) evaluate the margin of 10 to determine if it was unnecessarily large. A probabilistic approach was undertaken to conduct fracture evaluations of circumferentially cracked pipes for leak-rate-detection applications. Sixteen nuclear piping systems in BWR and PWR plants were analyzed to evaluate conditional failure probability and effects of crack-morphology variability on the current margins used in leak rate detection for leak-before-break.« less

  4. Risk stratification of ambulatory patients with advanced heart failure undergoing evaluation for heart transplantation.

    PubMed

    Kato, Tomoko S; Stevens, Gerin R; Jiang, Jeffrey; Schulze, P Christian; Gukasyan, Natalie; Lippel, Matthew; Levin, Alison; Homma, Shunichi; Mancini, Donna; Farr, Maryjane

    2013-03-01

    Risk stratification of ambulatory heart failure (HF) patients has relied on peak VO(2)<14 ml/kg/min. We investigated whether additional clinical variables might further specify risk of death, ventricular assist device (VAD) implantation (INTERMACS <4) or heart transplantation (HTx, Status 1A or 1B) within 1 year after HTx evaluation. We hypothesized that right ventricular stroke work index (RVSWI), pulmonary capillary wedge pressure (PCWP) and the model for end-stage liver disease-albumin score (MELD-A) would be additive prognostic predictors. We retrospectively collected data on 151 ambulatory patients undergoing HTx evaluation. Primary outcomes were defined as HTx, LVAD or death within 1 year after evaluation. Average age in our cohort was 55 ± 11.1 years, 79.1% were male and 39% had an ischemic etiology (LVEF 21 ± 10.5% and peak VO(2) 12.6 ± 3.5 ml/kg/min). Fifty outcomes (33.1%) were observed (27 HTxs, 15 VADs and 8 deaths). Univariate logistic regression showed a significant association of RVSWI (OR 0.47, p = 0.036), PCWP (OR 2.65, p = 0.007) and MELD-A (OR 2.73, p = 0.006) with 1-year events. Stepwise regression showed an independent correlation of RVSWI<5gm-m(2)/beat (OR 6.70, p < 0.01), PCWP>20 mm Hg (OR 5.48, p < 0.01), MELD-A>14 (OR 3.72, p< 0.01) and peak VO(2)<14 ml/kg/min (OR 3.36, p = 0.024) with 1-year events. A scoring system was developed: MELD-A>14 and peak VO(2)<14-1 point each; and PCWP>20 and RVSWI<5-2 points each. A cut-off at≥4 demonstrated a 54% sensitivity and 88% specificity for 1-year events. Ambulatory HF patients have significant 1-year event rates. Risk stratification based on exercise performance, left-sided congestion, right ventricular dysfunction and liver congestion allows prediction of 1-year prognosis. Our findings support early and timely referral for VAD and/or transplant. Copyright © 2013 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

  5. Evaluation of Peripheral Blood Circulation Disorder in Scleroderma Patients Using an Optical Sensor with a Pressurization Mechanism

    PubMed Central

    Yamakoshi, Yoshiki

    2016-01-01

    Blood circulation function of peripheral blood vessels in skin dermis was evaluated employing an optical sensor with a pressurization mechanism using the blood outflow and reflow characteristics. The device contains a light source and an optical sensor. When applied to the skin surface, it first exerts the primary pressure (higher than the systolic blood pressure), causing an outflow of blood from the dermal peripheral blood vessels. After two heartbeats, the pressure is lowered (secondary pressure) and blood reflows into the peripheral blood vessels. Hemoglobin concentration, which changes during blood outflow and reflow, is derived from the received light intensity using the Beer–Lambert law. This method was evaluated in 26 healthy female volunteers and 26 female scleroderma patients. In order to evaluate the blood circulation function of the peripheral blood vessels of scleroderma patients, pressurization sequence which consists of primary pressure followed by secondary pressure was adopted. Blood reflow during the first heartbeat period after applying the secondary pressure of 40mmHg was (mean±SD) 0.059±0.05%mm for scleroderma patients and 0.173±0.104%mm for healthy volunteers. Blood reflow was significantly lower in scleroderma patients than in healthy volunteers (p<0.05). This result indicates that the information necessary for assessing blood circulation disorder of peripheral blood vessels in scleroderma patients is objectively obtained by the proposed method. PMID:27479094

  6. Evaluation of Peripheral Blood Circulation Disorder in Scleroderma Patients Using an Optical Sensor with a Pressurization Mechanism.

    PubMed

    Yamakoshi, Yoshiki; Motegi, Sei-Ichiro; Ishikawa, Osamu

    2016-01-01

    Blood circulation function of peripheral blood vessels in skin dermis was evaluated employing an optical sensor with a pressurization mechanism using the blood outflow and reflow characteristics. The device contains a light source and an optical sensor. When applied to the skin surface, it first exerts the primary pressure (higher than the systolic blood pressure), causing an outflow of blood from the dermal peripheral blood vessels. After two heartbeats, the pressure is lowered (secondary pressure) and blood reflows into the peripheral blood vessels. Hemoglobin concentration, which changes during blood outflow and reflow, is derived from the received light intensity using the Beer-Lambert law. This method was evaluated in 26 healthy female volunteers and 26 female scleroderma patients. In order to evaluate the blood circulation function of the peripheral blood vessels of scleroderma patients, pressurization sequence which consists of primary pressure followed by secondary pressure was adopted. Blood reflow during the first heartbeat period after applying the secondary pressure of 40mmHg was (mean±SD) 0.059±0.05%mm for scleroderma patients and 0.173±0.104%mm for healthy volunteers. Blood reflow was significantly lower in scleroderma patients than in healthy volunteers (p<0.05). This result indicates that the information necessary for assessing blood circulation disorder of peripheral blood vessels in scleroderma patients is objectively obtained by the proposed method.

  7. Evaluation Criteria of Noninvasive Telemonitoring for Patients With Heart Failure: Systematic Review.

    PubMed

    Farnia, Troskah; Jaulent, Marie-Christine; Steichen, Olivier

    2018-01-16

    Telemonitoring can improve heart failure (HF) management, but there is no standardized evaluation framework to comprehensively evaluate its impact. Our objectives were to list the criteria used in published evaluations of noninvasive HF telemonitoring projects, describe how they are used in the evaluation studies, and organize them into a consistent scheme. Articles published from January 1990 to August 2015 were obtained through MEDLINE, Web of Science, and EMBASE. Articles were eligible if they were original reports of a noninvasive HF telemonitoring evaluation study in the English language. Studies of implantable telemonitoring devices were excluded. Each selected article was screened to extract the description of the telemonitoring project and the evaluation process and criteria. A qualitative synthesis was performed. We identified and reviewed 128 articles leading to 52 evaluation criteria classified into 6 dimensions: clinical, economic, user perspective, educational, organizational, and technical. The clinical and economic impacts were evaluated in more than 70% of studies, whereas the educational, organizational, and technical impacts were studied in fewer than 15%. User perspective was the most frequently covered dimension in the development phase of telemonitoring projects, whereas clinical and economic impacts were the focus of later phases. Telemonitoring evaluation frameworks should cover all 6 dimensions appropriately distributed along the telemonitoring project lifecycle. Our next goal is to build such a comprehensive evaluation framework for telemonitoring and test it on an ongoing noninvasive HF telemonitoring project. ©Troskah Farnia, Marie-Christine Jaulent, Olivier Steichen. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 16.01.2018.

  8. Disease management: remote monitoring in heart failure patients with implantable defibrillators, resynchronization devices, and haemodynamic monitors.

    PubMed

    Abraham, William T

    2013-06-01

    Heart failure represents a major public health concern, associated with high rates of morbidity and mortality. A particular focus of contemporary heart failure management is reduction of hospital admission and readmission rates. While optimal medical therapy favourably impacts the natural history of the disease, devices such as cardiac resynchronization therapy devices and implantable cardioverter defibrillators have added incremental value in improving heart failure outcomes. These devices also enable remote patient monitoring via device-based diagnostics. Device-based measurement of physiological parameters, such as intrathoracic impedance and heart rate variability, provide a means to assess risk of worsening heart failure and the possibility of future hospitalization. Beyond this capability, implantable haemodynamic monitors have the potential to direct day-to-day management of heart failure patients to significantly reduce hospitalization rates. The use of a pulmonary artery pressure measurement system has been shown to significantly reduce the risk of heart failure hospitalization in a large randomized controlled study, the CardioMEMS Heart Sensor Allows Monitoring of Pressure to Improve Outcomes in NYHA Class III Heart Failure Patients (CHAMPION) trial. Observations from a pilot study also support the potential use of a left atrial pressure monitoring system and physician-directed patient self-management paradigm; these observations are under further investigation in the ongoing LAPTOP-HF trial. All these devices depend upon high-intensity remote monitoring for successful detection of parameter deviations and for directing and following therapy.

  9. [Acute renal failure after cardiac surgery: evaluation of the RIFLE criteria].

    PubMed

    Kallel, Sami; Triki, Zied; Abdenadher, Mohammed; Frikha, Imed; Jemel, Amine; Karoui, Abdelhamid

    2013-04-01

    Acute renal failure is a common complication is a common complication in cardiac surgery under cardiopulmonary bypass. It is associated with increased morbidity and mortality. Acute kidney injury (AKI) is a clinical entity encompassing the entire spectrum of acute renal failure, since minor alterations to the need for renal replacement therapy. The RIFLE criteria have been proposed for defining and classifying AKI. The aim of our study was to apply the RIFLE to a population of patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) and to assess its relevance in terms of risk factor for hospital mortality compared to other risk factors. In this prospective observational study, we included patients who were operated for programmed cardiac surgery. The assay of blood creatinine was performed at admission, after surgery and daily for 5 days post-surgery. The AKI was evaluated according to the criteria of classification RIFLE. The patients were divided into three levels of severity based on plasmatic creatinine (R: Risk=creatinine×1.5; I: Injury=creatinine×2; F: Failure=creatinine×3). We have analyzed the different perioperative parameters and we sought associations with the occurrence of AKI. We also studied the impact of AKI on length of stay in ICU and mortality early and late. One hundred and thirty-six patients were included. AKI was diagnosed in 17.6% of patients (RIFLE-R: 8.8%, RIFLE-I: 5.9% and RIFLE-F: 2.9%). AKI significantly prolongs the duration of ICU stay (7±3.8 versus 5±2.3 days; P=0.02). RIFLE-R patients had a mortality of 8.3%, compared to 12.5% for I and 50% for F. Patients without PORD had a mortality of 1.8%. In univariate analysis, age, the EURO score, preoperative renal dysfunction, duration of aortic clamping, duration of CPB and C-reactive protein (CRP) were significantly associated with the occurrence of AKI. In multivariate analysis only preoperative renal dysfunction (clearance less than 63 mL/min) and CRP greater than 158

  10. Positive inotropes in heart failure: a review article

    PubMed Central

    Amin, Ahmad; Maleki, Majid

    2012-01-01

    Increasing myocardial contractility has long been considered a big help for patients with systolic heart failure, conferring an augmented haemodynamic profile in terms of higher cardiac output, lower cardiac filling pressure and better organ perfusion. Though concerns have been raised over the safety issues regarding the clinical trials of different inotropes in hearts with systolic dysfunction, they still stand as a main therapeutic strategy in many centres dealing with such patients. They must be used as short in duration, low in dose and stopped as early as possible. Evidence-based guidelines have provided clinicians with valuable data for better applying inotropes in heart failure patients. In this paper, the authors address clinical trials with different agents used for increasing cardiac contractility in heart failure patients. Furthermore, the authors focus on recent guidelines on making the most out of inotropes in heart failure patients. PMID:27326019

  11. Surface topography and bond strengths of feldspathic porcelain prepared using various sandblasting pressures.

    PubMed

    Moravej-Salehi, Elham; Moravej-Salehi, Elahe; Valian, Azam

    2016-11-01

    The purpose of this study was to determine the bond strength of composite resin to feldspathic porcelain and its surface topography after sandblasting at different pressures. In this in vitro study, 68 porcelain disks were fabricated and randomly divided into four groups of 17. The porcelain surface in group 1 was etched with hydrofluoric acid. Groups 2, 3, and 4 were sandblasted at 2, 3 and 4 bars pressure, respectively. Surface topography of seven samples in each of the four groups was examined by a scanning electron microscope (SEM). The remaining 40 samples received the same silane agent, bonding agent, and composite resin and they were then subjected to 5000 thermal cycles and evaluated for shear bond strength. Data were analyzed using one-way anova. The mode of failure was determined using stereomicroscope and SEM. The highest shear bond strength was seen in group 4. however, statistically significant differences were not seen between the groups (P = 0.780). The most common mode of failure was cohesive in porcelain. The SEM showed different patterns of hydrofluoric acid etching and sandblasting. Increasing the sandblasting pressure increased the surface roughness of feldspathic porcelain but no difference in bond strength occurred. © 2015 Wiley Publishing Asia Pty Ltd.

  12. Sensor failure detection for jet engines

    NASA Technical Reports Server (NTRS)

    Beattie, E. C.; Laprad, R. F.; Akhter, M. M.; Rock, S. M.

    1983-01-01

    Revisions to the advanced sensor failure detection, isolation, and accommodation (DIA) algorithm, developed under the sensor failure detection system program were studied to eliminate the steady state errors due to estimation filter biases. Three algorithm revisions were formulated and one revision for detailed evaluation was chosen. The selected version modifies the DIA algorithm to feedback the actual sensor outputs to the integral portion of the control for the nofailure case. In case of a failure, the estimates of the failed sensor output is fed back to the integral portion. The estimator outputs are fed back to the linear regulator portion of the control all the time. The revised algorithm is evaluated and compared to the baseline algorithm developed previously.

  13. Both high and low HbA1c predict incident heart failure in type 2 diabetes mellitus.

    PubMed

    Parry, Helen M; Deshmukh, Harshal; Levin, Daniel; Van Zuydam, Natalie; Elder, Douglas H J; Morris, Andrew D; Struthers, Allan D; Palmer, Colin N A; Doney, Alex S F; Lang, Chim C

    2015-03-01

    Type 2 diabetes mellitus is an independent risk factor for heart failure development, but the relationship between incident heart failure and antecedent glycemia has not been evaluated. The Genetics of Diabetes Audit and Research in Tayside Study study holds data for 8683 individuals with type 2 diabetes mellitus. Dispensed prescribing, hospital admission data, and echocardiography reports were linked to extract incident heart failure cases from December 1998 to August 2011. All available HbA1c measures until heart failure development or end of study were used to model HbA1c time-dependently. Individuals were observed from study enrolment until heart failure development or end of study. Proportional hazard regression calculated heart failure development risk associated with specific HbA1c ranges accounting for comorbidities associated with heart failure, including blood pressure, body mass index, and coronary artery disease. Seven hundred and one individuals with type 2 diabetes mellitus (8%) developed heart failure during follow up (mean 5.5 years, ±2.8 years). Time-updated analysis with longitudinal HbA1c showed that both HbA1c <6% (hazard ratio =1.60; 95% confidence interval, 1.38-1.86; P value <0.0001) and HbA1c >10% (hazard ratio =1.80; 95% confidence interval, 1.60-2.16; P value <0.0001) were independently associated with the risk of heart failure. Both high and low HbA1c predicted heart failure development in our cohort, forming a U-shaped relationship. © 2015 American Heart Association, Inc.

  14. In-hospital management and outcomes of acute coronary syndromes in relation to prior history of heart failure.

    PubMed

    Zhang, Hanfei; Goodman, Shaun G; Yan, Raymond T; Steg, Ph Gabriel; Kornder, Jan M; Gyenes, Gabor T; Grondin, Francois R; Brieger, David; DeYoung, J Paul; Gallo, Richard; Yan, Andrew T

    2016-06-01

    The prognostic significance of prior heart failure in acute coronary syndromes has not been well studied. Accordingly, we evaluated the baseline characteristics, management patterns and clinical outcomes in patients with acute coronary syndromes who had prior heart failure. The study population consisted of acute coronary syndrome patients in the Global Registry of Acute Coronary Events, expanded Global Registry of Acute Coronary Events and Canadian Registry of Acute Coronary Events between 1999 and 2008. Of the 13,937 eligible patients (mean age 66±13 years, 33% female and 28.3% with ST-elevation myocardial infarction), 1498 (10.7%) patients had a history of heart failure. Those with prior heart failure tended to be older, female and had lower systolic blood pressure, higher Killip class and creatinine on presentation. Prior heart failure was also associated with significantly worse left ventricular systolic function and lower rates of cardiac catheterization and coronary revascularization. The group with previous heart failure had significantly higher rates of acute decompensated heart failure, cardiogenic shock, myocardial (re)infarction and mortality in hospital. In multivariable analysis, prior heart failure remained an independent predictor of in-hospital mortality (odds ratio 1.48, 95% confidence interval 1.08-2.03, p=0.015). Prior heart failure was associated with high risk features on presentation and adverse outcomes including higher adjusted in-hospital mortality in acute coronary syndrome patients. However, acute coronary syndrome patients with prior heart failure were less likely to receive evidence-based therapies, suggesting potential opportunities to target more intensive treatment to improve their outcome. © The European Society of Cardiology 2015.

  15. Modeling Dynamic Anisotropic Behaviour and Spall Failure in Commercial Aluminium Alloys AA7010

    NASA Astrophysics Data System (ADS)

    Mohd Nor, M. K.; Ma'at, N.; Ho, C. S.

    2018-04-01

    This paper presents a finite strain constitutive model to predict a complex elastoplastic deformation behaviour involves very high pressures and shockwaves in orthotropic materials of aluminium alloys. The previous published constitutive model is used as a reference to start the development in this work. The proposed formulation that used a new definition of Mandel stress tensor to define Hill's yield criterion and a new shock equation of state (EOS) of the generalised orthotropic pressure is further enhanced with Grady spall failure model to closely predict shockwave propagation and spall failure in the chosen commercial aluminium alloy. This hyperelastic-plastic constitutive model is implemented as a new material model in the Lawrence Livermore National Laboratory (LLNL)-DYNA3D code of UTHM's version, named Material Type 92 (Mat92). The implementations of a new EOS of the generalised orthotropic pressure including the spall failure are also discussed in this paper. The capability of the proposed constitutive model to capture the complex behaviour of the selected material is validated against range of Plate Impact Test data at 234, 450 and 895 ms-1 impact velocities.

  16. Design of the heart failure endpoint evaluation of AII-antagonist losartan (HEAAL) study in patients intolerant to ACE-inhibitor.

    PubMed

    Konstam, Marvin A; Poole-Wilson, Philip A; Dickstein, Kenneth; Drexler, Helmut; Justice, Steven J; Komajda, Michel; Malbecq, William; Martinez, Felipe A; Neaton, James D; Riegger, Gunter A J; Guptha, Soneil

    2008-09-01

    In patients with heart failure and reduced left ventricular ejection fraction, angiotensin receptor blockers have been found to reduce mortality and morbidity and to prevent or reverse left ventricular remodelling, compared to optimized background treatment. In light of these data, The Heart failure Endpoint evaluation of Angiotensin II Antagonist Losartan (HEAAL) study was developed to determine whether losartan 150 mg is superior to losartan 50 mg (antihypertensive dose) in reducing morbidity and mortality among patients with symptomatic heart failure who are intolerant of angiotensin-converting enzyme (ACE)-inhibitors. To compare the effect of high and moderate doses of losartan on the primary endpoint of all-cause mortality and hospitalisation due to heart failure in patients (n = 3834) with symptomatic heart failure and an ejection fraction < or = 40% who are intolerant of ACE-inhibitor treatment. This paper presents the rationale, trial design, and baseline characteristics of the study population. The study, which completed recruitment on 31 March 2005, is event-driven and is estimated to accrue the target of 1710 adjudicated primary events during the latter half of 2008. The results of HEAAL should facilitate selection of an optimal dosing regimen for losartan in patients with symptomatic heart failure who are intolerant of ACE-inhibitors.

  17. [Evaluation of a chronic fatigue in patients with moderate-to-severe chronic heart failure].

    PubMed

    Jasiukeviciene, Lina; Vasiliauskas, Donatas; Kavoliūniene, Ausra; Marcinkeviciene, Jolanta; Grybauskiene, Regina; Grizas, Vytautas; Tumyniene, Vida

    2008-01-01

    To evaluate the chronic fatigue and its relation to the function of hypothalamus-pituitary-adrenal axis in patients with New York Heart Association (NYHA) functional class III-IV chronic heart failure. A total of 170 patients with NYHA functional class III-IV chronic heart failure completed MFI-20L, DUFS, and DEFS questionnaires assessing chronic fatigue and underwent echocardiography. Blood cortisol concentration was assessed at 8:00 am and 3:00 pm, and plasma N-terminal brain natriuretic pro-peptide (NT-proBNP) concentration was measured at 8:00 am. Neurohumoral investigations were repeated before cardiopulmonary exercise test and after it. The results of all questionnaires showed that 100% of patients with NYHA functional class III-IV heart failure complained of chronic fatigue. The level of overall fatigue was 54.5+/-31.5 points; physical fatigue - 56.8+/-24.6 points. Blood cortisol concentration at 8:00 am was normal (410.1+/-175.1 mmol/L) in majority of patients. Decreased concentration was only in four patients (122.4+/-15.5 mmol/L); one of these patients underwent heart transplantation. In the afternoon, blood cortisol concentration was insufficiently decreased (355.6+/-160.3 mmol/L); reaction to a physical stress was attenuated (Delta 92.9 mmol/L). Plasma NT-proBNP concentration was 2188.9+/-1852.2 pg/L; reaction to a physical stress was diminished (Delta 490.3 pg/L). All patients with NYHA class III-IV heart failure complained of daily chronic fatigue. Insufficiently decreased blood cortisol concentration in the afternoon showed that in the presence of chronic fatigue in long-term cardiovascular organic disease, disorder of a hypothalamus-pituitary-adrenal axis is involved.

  18. Cardio-Pulmonary Stethoscope: Clinical Validation With Heart Failure and Hemodialysis Patients.

    PubMed

    Iskander, Magdy F; Seto, Todd B; Perron, Ruthsenne Rg; Lim, Eunjung; Qazi, Farhan

    2018-05-01

    The purpose of this study is to evaluate the accuracy of a noninvasive radiofrequency-based device, the Cardio-Pulmonary Stethoscope (CPS), to monitor heart and respiration rates, and detect changes in lung water content in human experiments and clinical trials. Three human populations (healthy subjects ( ), heart failure (), and hemodialysis () patients) were enrolled in this study. The study was conducted at the University of Hawaii and the Queen's Medical Center in Honolulu, HI, USA. Measurement of heart and respiration rates for all patients was compared with standard FDA - approved monitoring methods. For lung water measurements, CPS data were compared with simultaneous pulmonary capillary wedge pressure (PCWP) measurements for heart failure patients, and with change in weight of extracted fluid for hemodialysis patients. Statistical correlation methods (Pearson, mixed, and intraclass) were used to compare the data and examine accuracy of CPS results. Results show that heart and respiration rates of all patients have excellent correlation factors, r≥0.9. Comparisons with fluid removed during hemodialysis treatment showed correlation factor of to 1, while PCWP measurements of heart failure patients had correlation factor of to 0.97. These results suggest that CPS technology accurately quantifies heart and respiration rates and measure fluid changes in the lungs. The CPS has the potential to accurately monitor lung fluid status noninvasively and continuously in a clinical and outpatient setting. Early and efficient management of lung fluid status is key in managing chronic conditions such heart failure, pulmonary hypertension, and acute respiration distress syndrome.

  19. Achievement of Target Blood Pressure Levels among Japanese Workers with Hypertension and Healthy Lifestyle Characteristics Associated with Therapeutic Failure.

    PubMed

    Kudo, Nagako; Yokokawa, Hirohide; Fukuda, Hiroshi; Sanada, Hironobu; Miwa, Yuichi; Hisaoka, Teruhiko; Isonuma, Hiroshi

    2015-01-01

    Few studies have examined Japanese with regard to the achievement rates for target blood pressure levels, or the relationship between these rates and healthy lifestyle characteristics in patients with hypertension as defined by the newly established hypertension management guidelines (JSH2014). The aim of this study was to elucidate achievement rates and examine healthy lifestyle characteristics associated with achievement status among Japanese. This cross-sectional study, conducted in January-December 2012, examined blood pressure control and healthy lifestyle characteristics in 8,001 Japanese workers with hypertension (mean age, 57.0 years; 78.8% were men) who participated in a workplace health checkup. Data were collected from workplace medical checkup records and participants' self-administered questionnaires. We divided into 5 groups [G1; young, middle-aged, and early-phase elderly patients (65-74 years old) without diabetes mellitus or chronic kidney disease (CKD) (<140/90 mmHg), G2; late-phase elderly patients (≥75 years old) without diabetes mellitus or CKD (<150/90 mmHg), G3; diabetic patients (<130/80 mmHg), G4; patients with CKD (<130/80 mmHg), and G5; patients with cerebrovascular and/or coronary artery diseases (<140/90 mmHg)] according to JSH2014. And then, achievement rates were calculated in each group. Multivariate analysis identified healthy lifestyle characteristics associated with "therapeutic failure" of target blood pressure. Target blood pressures were achieved by 60.2% of young, middle-aged, and early-phase elderly patients (G1), 71.4% of late-phase elderly patients (G2), 30.5% of diabetic patients (G3), 33.4% of those with chronic kidney disease (G4), and 66.0% of those with cerebrovascular and/or coronary artery diseases (G5). A body mass index of 18.5-24.9 and non-daily alcohol consumption were protective factors, and adequate sleep was found to contribute to therapeutic success. We found low achievement rates for treatment goals among

  20. Applying the Growth Failure in CKD Consensus Conference: evaluation and treatment algorithm in children with chronic kidney disease.

    PubMed

    Mahan, John D

    2006-07-01

    Growth failure is a common and significant clinical problem for children with chronic kidney disease (CKD), particularly those with chronic renal insufficiency (CRI). Children with CRI (typically defined by a glomerular filtration rate [GFR] <75 mL/min/1.73 m2) who have growth impairment exhibit a variety of medical and psychological problems in addition to increased mortality. Growth failure in children with CKD is usually multifactorial in etiology, including abnormalities in the growth hormone (GH)-insulin-like growth factor (IGF)-I axis and a variety of nutritional and metabolic concerns characteristic of CKD. Proper management of these factors contributes to better growth in affected children. Although the safety and efficacy of recombinant human GH (rhGH) therapy in promoting growth in children with CKD are well established, recent data indicate that the use of rhGH administration in children with CKD and growth failure remains low. Recently, guidelines were developed by the Consensus Conference for Evaluation and Treatment of Growth Failure in Children with CKD. This paper focuses on the application of these guidelines to children with CKD.

  1. Cardiac magnetic resonance imaging in heart failure: where the alphabet begins!

    PubMed

    Aljizeeri, Ahmed; Sulaiman, Abdulbaset; Alhulaimi, Naji; Alsaileek, Ahmed; Al-Mallah, Mouaz H

    2017-07-01

    Cardiac Magnetic Resonance Imaging has become a cornerstone in the evaluation of heart failure. It provides a comprehensive evaluation by answering all the pertinent clinical questions across the full pathological spectrum of heart failure. Nowadays, CMR is considered the gold standard in evaluation of ventricular volumes, wall motion and systolic function. Through its unique ability of tissue characterization, it provides incremental diagnostic and prognostic information and thus has emerged as a comprehensive imaging modality in heart failure. This review outlines the role of main conventional CMR sequences in the evaluation of heart failure and their impact in the management and prognosis.

  2. X-33 LH2 Tank Failure Investigation Findings

    NASA Technical Reports Server (NTRS)

    Niedermeyer, M.

    2001-01-01

    The X-33 liquid hydrogen tank failure investigation found the following: (1) The inner skin microcracked and hydrogen infiltrated into it; (2) The cracks grew larger under pressure; (3) When pressure was removed, the cracks closed slightly; (4) When the tank was drained and warmed, the cracks closed and blocked the leak path; (5) Foreign object debris (FOD) and debond areas provided an opportunity for a leak path; and (6) There is still hydrogen in the other three lobes today.

  3. Cognitive impairment in heart failure patients

    PubMed Central

    Leto, Laura; Feola, Mauro

    2014-01-01

    Cognitive damage in heart failure (HF) involves different domains thus interfering with the ability for single patient to self-care and to cope with treatment regimens, modifying symptoms and health behaviours. Many cerebral and functional changes were detected in brain imaging, involving areas of both grey and white matter deputed to cognition. Although various instruments are available to explore cognition, no consensus was obtained on better tools to be used in HF population. Reduction in cerebral blood flow, decreased cardiac output, alterations of cerebrovascular reactivity and modification of blood pressure levels are the main features involved in the etiopathogenetic mechanisms of cognitive deficit. Several cardiac variables, laboratory parameters, demographic and clinical elements were studied for their possible relation with cognition and should be properly evaluated to define patients at increased risk of impairment. The present review gathers available data pointing out assured information and discussing possible areas of research development. PMID:25593581

  4. Economic Evaluations of Strategies to Prevent Hospital-Acquired Pressure Injuries.

    PubMed

    Ocampo, Wrechelle; Cheung, Amanda; Baylis, Barry; Clayden, Nancy; Conly, John M; Ghali, William A; Ho, Chester H; Kaufman, Jaime; Stelfox, Henry T; Hogan, David B

    2017-07-01

    To provide information from a review of literature about economic evaluations of preventive strategies for pressure injuries (PIs). This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care. After participating in this educational activity, the participant should be better able to:1. Identify the purpose and methods used for this study.2. Compare costs and effectiveness related to preventative strategies for PIs. BACKGROUND: Pressure injuries (PIs) are a common and resource-intensive challenge for acute care hospitals worldwide. While a number of preventive strategies have the potential to reduce the cost of hospital-acquired PIs, it is unclear what approach is the most effective. The authors performed a narrative review of the literature on economic evaluations of preventive strategies to survey current findings and identify important factors in economic assessments. Ovid, MEDLINE, NHS Economic Evaluation Databases, and the Cochrane Database of Systematic ReviewsSELECTION CRITERIA: Potentially relevant original research articles and systematic reviews were considered. Selection criteria included articles that were written in English, provided data on cost or economic evaluations of preventive strategies of PIs in acute care, and published between January 2004 and September 2015. Data were abstracted from the articles using a standardized approach to evaluate how the items on the Consolidated Health Economic Evaluation Reporting Standards checklist were addressed. The searches identified 192 references. Thirty-three original articles were chosen for full-text reviews. Nineteen of these articles provided clear descriptions of interventions, study methods, and outcomes considered. Limitations in the available literature prevent firm conclusions from being reached about the relative economic merits of the various approaches to the prevention of PIs. The authors' review

  5. Cerebral blood flow in patients with congestive heart failure treated with captopril.

    PubMed

    Paulson, O B; Jarden, J O; Godtfredsen, J; Vorstrup, S

    1984-05-31

    The effect of captopril on cerebral blood flow was studied in five patients with severe congestive heart failure and in five control subjects. Cerebral blood flow was measured by inhalation of 133xenon and registration of its uptake and washout from the brain by single photon emission computer tomography. In addition, cerebral (internal jugular) venous oxygen tension was determined in the controls. The measurements were made before and 15, 60, and 180 minutes after a single oral dose of captopril (6.25 mg in patients with congestive heart failure and 25 mg in controls). Despite a marked decrease in blood pressure, cerebral blood flow increased slightly in the patients with severe congestive heart failure. When a correction was applied to take account of a change in arterial carbon dioxide tension, however, cerebral blood flow was unchanged after captopril administration even in patients with the greatest decrease in blood pressure, in whom a decrease in cerebral blood flow might have been expected. In the controls, blood pressure was little affected by captopril, whereas a slight, but not statistically significant, decrease in cerebral blood flow was observed. The cerebral venous oxygen tension decreased concomitantly.

  6. Evaluating the risk of eye injuries: intraocular pressure during high speed projectile impacts.

    PubMed

    Duma, Stefan M; Bisplinghoff, Jill A; Senge, Danielle M; McNally, Craig; Alphonse, Vanessa D

    2012-01-01

    To evaluate the risk of eye injuries by determining intraocular pressure during high speed projectile impacts. A pneumatic cannon was used to impact eyes with a variety of projectiles at multiple velocities. Intraocular pressure was measured with a small pressure sensor inserted through the optic nerve. A total of 36 tests were performed on 12 porcine eyes with a range of velocities between 6.2 m/s and 66.5 m/s. Projectiles selected for the test series included a 6.35  mm diameter metal ball, a 9.25  mm diameter aluminum rod, and an 11.16  mm diameter aluminum rod. Experiments were designed with velocities in the range of projectile consumer products such as toy guns. A range of intraocular pressures ranged between 2017 mmHg to 26,426 mmHg (39 psi-511 psi). Four of the 36 impacts resulted in globe rupture. Intraocular pressures dramatically above normal physiological pressure were observed for high speed projectile impacts. These pressure data provide critical insight to chronic ocular injuries and long-term complications such as glaucoma and cataracts.

  7. [Quantitative evaluation of resource and environment pressure in Qinghai Province, China based on footprint family].

    PubMed

    Ma, Cai Hong; Zhao, Jing

    2016-04-22

    In order to effectively evaluate the influence of human activities on the resource and environment, this paper constructed an resource and environment pressure evaluation system based on footprint family, and calculated the ecological footprint, carbon footprint, water footprint, and resource and environment pressure in Qinghai Province. The results showed that from 1990 to 2013, the ecological footprint per capita in Qinghai Province increased from 1.32 hm 2 to 3.32 hm 2 , and biological capacity per capita decreased from 2.33 hm 2 to 2.07 hm 2 . Since 2006 there was ecological deficit. However, the biomass surplus existed during 1990-2013. The carbon footprint per capita increased from 5.82 t to 15.85 t, which had been more than 7.93 times of the target to address climate change. The water footprint per capita decreased from 967.67 m 3 to 732.05 m 3 . Since 1990, the ecological pressure was at low grade (1 b ), greenhouse gas (GHG) emissions pressure was enhanced from low grade (1 b ) to above-average grade (2 b ), the water pressure was at very low grade (1 a ), the resource and environment pressure increased from very low grade (1 a ) to low grade (1 b ). The rate of contribution of ecological pressure and water resource pressure to resources and environment pressure gradually decreased, whereas, the rate of contribution of GHG emission pressure to resources and environment pressure gradually increased. The resource and environment pressure had spatial heterogeneity. In 2013, it was at very high grade (3 b ) in Xining City, at above-average grade (2 b ) in Haidong City, at below-average grade (2 a ) in Haixi State and atvery low grade (1 a ) in the rest regions. The main resource and environment pressure source also had obvious spatial heterogeneity. In future, differentiation strategies should be taken in the decompression progress.

  8. Program Helps In Analysis Of Failures

    NASA Technical Reports Server (NTRS)

    Stevenson, R. W.; Austin, M. E.; Miller, J. G.

    1993-01-01

    Failure Environment Analysis Tool (FEAT) computer program developed to enable people to see and better understand effects of failures in system. User selects failures from either engineering schematic diagrams or digraph-model graphics, and effects or potential causes of failures highlighted in color on same schematic-diagram or digraph representation. Uses digraph models to answer two questions: What will happen to system if set of failure events occurs? and What are possible causes of set of selected failures? Helps design reviewers understand exactly what redundancies built into system and where there is need to protect weak parts of system or remove them by redesign. Program also useful in operations, where it helps identify causes of failure after they occur. FEAT reduces costs of evaluation of designs, training, and learning how failures propagate through system. Written using Macintosh Programmers Workshop C v3.1. Can be linked with CLIPS 5.0 (MSC-21927, available from COSMIC).

  9. A Sample of NASA Langley Unsteady Pressure Experiments for Computational Aerodynamics Code Evaluation

    NASA Technical Reports Server (NTRS)

    Schuster, David M.; Scott, Robert C.; Bartels, Robert E.; Edwards, John W.; Bennett, Robert M.

    2000-01-01

    As computational fluid dynamics methods mature, code development is rapidly transitioning from prediction of steady flowfields to unsteady flows. This change in emphasis offers a number of new challenges to the research community, not the least of which is obtaining detailed, accurate unsteady experimental data with which to evaluate new methods. Researchers at NASA Langley Research Center (LaRC) have been actively measuring unsteady pressure distributions for nearly 40 years. Over the last 20 years, these measurements have focused on developing high-quality datasets for use in code evaluation. This paper provides a sample of unsteady pressure measurements obtained by LaRC and available for government, university, and industry researchers to evaluate new and existing unsteady aerodynamic analysis methods. A number of cases are highlighted and discussed with attention focused on the unique character of the individual datasets and their perceived usefulness for code evaluation. Ongoing LaRC research in this area is also presented.

  10. Differential activation of stress-response signaling in load-induced cardiac hypertrophy and failure

    PubMed Central

    Rothermel, Beverly A.; Berenji, Kambeez; Tannous, Paul; Kutschke, William; Dey, Asim; Nolan, Bridgid; Yoo, Ki-Dong; Demetroulis, Elaine; Gimbel, Michael; Cabuay, Barry; Karimi, Mohsen; Hill, Joseph A.

    2014-01-01

    Hypertrophic growth of the myocardium occurs in most forms of heart failure and may contribute to the pathogenesis of the failure state. Little is known about the regulatory mechanisms governing the often-coexisting phenotypes of hypertrophy, systolic failure, and diastolic stiffness that characterize clinical disease. We hypothesized that intracellular signaling pathways are differentially activated by graded degrees of hemodynamic stress. To test this, we developed models of graded pressure stress in mice and used them to directly compare compensated hypertrophy and pressure-overload heart failure. Surgical interventions were designed to be similar, on either side of a threshold separating compensated from decompensated responses. Our findings revealed two dramatically different hypertrophic phenotypes with only modest differences in the activation of relevant intracellular signaling pathways. Furthermore, we uncovered a functional requirement of calcineurin signaling in each model such that calcineurin suppression blunted hypertrophic growth. Remarkably, in each case, suppression of calcineurin signaling was not associated with clinical deterioration or increased mortality. Profiles of stress-response signaling and Ca2+ handling differ between the steady-state, maintenance phases of load-induced cardiac hypertrophy and failure. This information may be useful in identifying novel targets of therapy in chronic disease. PMID:16033866

  11. Differential activation of stress-response signaling in load-induced cardiac hypertrophy and failure.

    PubMed

    Rothermel, Beverly A; Berenji, Kambeez; Tannous, Paul; Kutschke, William; Dey, Asim; Nolan, Bridgid; Yoo, Ki-Dong; Demetroulis, Elaine; Gimbel, Michael; Cabuay, Barry; Karimi, Mohsen; Hill, Joseph A

    2005-09-21

    Hypertrophic growth of the myocardium occurs in most forms of heart failure and may contribute to the pathogenesis of the failure state. Little is known about the regulatory mechanisms governing the often-coexisting phenotypes of hypertrophy, systolic failure, and diastolic stiffness that characterize clinical disease. We hypothesized that intracellular signaling pathways are differentially activated by graded degrees of hemodynamic stress. To test this, we developed models of graded pressure stress in mice and used them to directly compare compensated hypertrophy and pressure-overload heart failure. Surgical interventions were designed to be similar, on either side of a threshold separating compensated from decompensated responses. Our findings revealed two dramatically different hypertrophic phenotypes with only modest differences in the activation of relevant intracellular signaling pathways. Furthermore, we uncovered a functional requirement of calcineurin signaling in each model such that calcineurin suppression blunted hypertrophic growth. Remarkably, in each case, suppression of calcineurin signaling was not associated with clinical deterioration or increased mortality. Profiles of stress-response signaling and Ca2+ handling differ between the steady-state, maintenance phases of load-induced cardiac hypertrophy and failure. This information may be useful in identifying novel targets of therapy in chronic disease.

  12. Liver Stiffness Reflecting Right-Sided Filling Pressure Can Predict Adverse Outcomes in Patients With Heart Failure.

    PubMed

    Taniguchi, Tatsunori; Ohtani, Tomohito; Kioka, Hidetaka; Tsukamoto, Yasumasa; Onishi, Toshinari; Nakamoto, Kei; Katsimichas, Themistoklis; Sengoku, Kaoruko; Chimura, Misato; Hashimoto, Haruko; Yamaguchi, Osamu; Sawa, Yoshiki; Sakata, Yasushi

    2018-01-12

    This study sought to investigate whether elevated liver stiffness (LS) values at discharge reflect residual liver congestion and are associated with worse outcomes in patients with heart failure (HF). Transient elastography is a newly developed, noninvasive method for assessing LS, which can be highly reflective of right-sided filling pressure associated with passive liver congestion in patients with HF. LS values were determined for 171 hospitalized patients with HF before discharge using a Fibroscan device. The median LS value was 5.6 kPa (interquartile range: 4.4 to 8.1; range 2.4 to 39.7) and that of right-sided filling pressure, which was estimated based on LS, was 5.7 mm Hg (interquartile range: 4.1 to 8.2 mm Hg; range 0.1 to 18.9 mm Hg). The patients in the highest LS tertile (>6.9 kPa, corresponding to an estimated right-sided filling pressure of >7.1 mm Hg) had advanced New York Heart Association functional class, high prevalence of jugular venous distention and moderate/severe tricuspid regurgitation, large inferior vena cava (IVC) diameter, low hemoglobin and hematocrit levels, high serum direct bilirubin level, and a similar left ventricular ejection fraction compared with the lower tertiles. During follow-up periods (median: 203 days), 8 (5%) deaths and 33 (19%) hospitalizations for HF were observed. The patients in the highest LS group had a significantly higher mortality rate and HF rehospitalization (hazard ratio: 3.57; 95% confidence interval: 1.93 to 6.83; p < 0.001) compared with the other tertiles. Although LS correlated with IVC diameter and serum direct bilirubin and brain natriuretic peptide levels, LS values were predictive of worse outcomes, even after adjustment for these indices. These data suggest that LS is a useful index for assessing systemic volume status and predicting the severity of HF, and that the presence of liver congestion at discharge is associated with worse outcomes in patients with HF. Copyright © 2018 American

  13. When should we use nitrates in congestive heart failure?

    PubMed

    Vizzardi, Enrico; Bonadei, Ivano; Rovetta, Riccardo; D'Aloia, Antonio; Quinzani, Filippo; Curnis, Antonio; Dei Cas, Livio

    2013-02-01

    Organic nitrates remain among the oldest and most commonly employed drugs in cardiology. Although, in most cases, their use in acute and chronic heart failure is based on clinical practice, only a few clinical trials have been conducted to evaluate their use in acute and chronic heart failure, most of which compare them with other drugs to evaluate differing endpoints. The purpose of this review is to examine the various trials that have evaluated the use of nitrates in acute and chronic heart failure. © 2012 Blackwell Publishing Ltd.

  14. Decongestion: Diuretics and other therapies for hospitalized heart failure

    PubMed Central

    Vazir, Ali; Cowie, Martin R.

    2016-01-01

    Acute heart failure (AHF) is a potentially life-threatening clinical syndrome, usually requiring hospital admission. Often the syndrome is characterized by congestion, and is associated with long hospital admissions and high risk of readmission and further healthcare expenditure. Despite a limited evidence-base, diuretics remain the first-line treatment for congestion. Loop diuretics are typically the first-line diuretic strategy with some evidence that initial treatment with continuous infusion or boluses of high-dose loop diuretic is superior to an initial lower dose strategy. In patients who have impaired responsiveness to diuretics, the addition of an oral thiazide or thiazide-like diuretic to induce sequential nephron blockade can be beneficial. The use of intravenous low-dose dopamine is no longer supported in heart failure patients with preserved systolic blood pressure and its use to assist diuresis in patients with low systolic blood pressures requires further study. Mechanical ultrafiltration has been used to treat patients with heart failure and fluid retention, but the evidence-base is not robust, and its place in clinical practice is yet to be established. Several novel pharmacological agents remain under investigation. PMID:27056656

  15. Stress failure of pulmonary capillaries: role in lung and heart disease

    NASA Technical Reports Server (NTRS)

    West, J. B.; Mathieu-Costello, O.

    1992-01-01

    Pulmonary capillaries have extremely thin walls to allow rapid exchange of respiratory gases across them. Recently it has been shown that the wall stresses become very large when the capillary pressure is raised, and in anaesthetised rabbits, ultrastructural damage to the walls is seen at pressures of 40 mm Hg and above. The changes include breaks in the capillary endothelial layer, alveolar epithelial layer, and sometimes all layers of the wall. The strength of the thin part of the capillary wall can be attributed to the type IV collagen in the extracellular matrix. Stress failure of pulmonary capillaries results in a high-permeability form of oedema, or even frank haemorrhage, and is apparently the mechanism of neurogenic pulmonary oedema and high-altitude pulmonary oedema. It also explains the exercise-induced pulmonary haemorrhage that occurs in all racehorses. Several features of mitral stenosis are consistent with stress failure. Overinflation of the lung also leads to stress failure, a common cause of increased capillary permeability in the intensive care environment. Stress failure also occurs if the type IV collagen of the capillary wall is weakened by autoantibodies as in Goodpasture's syndrome. Neutrophil elastase degrades type IV collagen and this may be the starting point of the breakdown of alveolar walls that is characteristic of emphysema. Stress failure of pulmonary capillaries is a hitherto overlooked and potentially important factor in lung and heart disease.

  16. Bolus versus continuous low dose of enalaprilat in congestive heart failure with acute refractory decompensation.

    PubMed

    Podbregar, M; Voga, G; Horvat, M; Zuran, I; Krivec, B; Skale, R; Pareznik, R

    1999-01-01

    The first dose of angiotensin-converting enzyme (ACE) inhibitors may trigger a considerable fall of blood pressure in chronic heart failure. The response may be dose-related. To determine hemodynamic and systemic oxygenation effects of low-dose enalaprilat, we administered intravenous enalaprilat (0.004 mg/kg) as bolus (group B) or continuous 1-hour infusion (group C) in 20 patients with congestive heart failure due to ischemic heart disease with acute decompensation refractory to inotropic, vasodilator and diuretic therapy. Hemodynamic and systemic oxygenation variables were recorded at baseline (+0 min), +30, +60, +120, +180, and +360 min after the start of intervention. Mean arterial pressure (MAP) (p < 0. 001), mean pulmonary artery pressure (MPAP) (p < 0.001), pulmonary artery occlusion pressure (PAOP) (p < 0.001), oxygen extraction ratio (ER) (p < 0.026) decreased regardless of enalaprilat application. Compared to group B, there was in group C prolonged decrease of MAP, MPAP, PAOP, ER and increase of pulmonary artery oxyhemoglobin saturation in regard to baseline values. Cardiac index, heart rate, central venous pressure and oxygen consumption index did not change. A low dose of intravenous enalaprilat (0.004 mg/kg) can be used to safely improve hemodynamics and systemic oxygenation in congestive heart failure due to ischemic heart disease with acute refractory decompensation.

  17. Experimental Investigation on Deformation Failure Characteristics of Crystalline Marble Under Triaxial Cyclic Loading

    NASA Astrophysics Data System (ADS)

    Yang, Sheng-Qi; Tian, Wen-Ling; Ranjith, P. G.

    2017-11-01

    The deformation failure characteristics of marble subjected to triaxial cyclic loading are significant when evaluating the stability and safety of deep excavation damage zones. To date, however, there have been notably few triaxial experimental studies on marble under triaxial cyclic loading. Therefore, in this research, a series of triaxial cyclic tests was conducted to analyze the mechanical damage characteristics of a marble. The post-peak deformation of the marble changed gradually from strain softening to strain hardening as the confining pressure increased from 0 to 10 MPa. Under uniaxial compression, marble specimens showed brittle failure characteristics with a number axial splitting tensile cracks; in the range of σ 3 = 2.5-7.5 MPa, the marble specimens assumed single shear fracture characteristics with larger fracture angles of about 65°. However, at σ 3 = 10 MPa, the marble specimens showed no obvious shear fracture surfaces. The triaxial cyclic experimental results indicate that in the range of the tested confining pressures, the triaxial strengths of the marble specimens under cyclic loading were approximately equal to those under monotonic loading. With the increase in cycle number, the elastic strains of the marble specimens all increased at first and later decreased, achieving maximum values, but the plastic strains of the marble specimens increased nonlinearly. To evaluate quantitatively the damage extent of the marble under triaxial cyclic loading, a damage variable is defined according to the irreversible deformation for each cycle. The evolutions of the elastic modulus for the marble were characterized by four stages: material strengthening, material degradation, material failure and structure slippage. Based on the experimental results of the marble specimens under complex cyclic loading, the cohesion of the marble decreased linearly, but the internal friction angles did not depend on the damage extent. To describe the peak strength

  18. The application of probabilistic fracture analysis to residual life evaluation of embrittled reactor vessels

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dickson, T.L.; Simonen, F.A.

    1992-05-01

    Probabilistic fracture mechanics analysis is a major element of comprehensive probabilistic methodology on which current NRC regulatory requirements for pressurized water reactor vessel integrity evaluation are based. Computer codes such as OCA-P and VISA-II perform probabilistic fracture analyses to estimate the increase in vessel failure probability that occurs as the vessel material accumulates radiation damage over the operating life of the vessel. The results of such analyses, when compared with limits of acceptable failure probabilities, provide an estimation of the residual life of a vessel. Such codes can be applied to evaluate the potential benefits of plant-specific mitigating actions designedmore » to reduce the probability of failure of a reactor vessel. 10 refs.« less

  19. The application of probabilistic fracture analysis to residual life evaluation of embrittled reactor vessels

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dickson, T.L.; Simonen, F.A.

    1992-01-01

    Probabilistic fracture mechanics analysis is a major element of comprehensive probabilistic methodology on which current NRC regulatory requirements for pressurized water reactor vessel integrity evaluation are based. Computer codes such as OCA-P and VISA-II perform probabilistic fracture analyses to estimate the increase in vessel failure probability that occurs as the vessel material accumulates radiation damage over the operating life of the vessel. The results of such analyses, when compared with limits of acceptable failure probabilities, provide an estimation of the residual life of a vessel. Such codes can be applied to evaluate the potential benefits of plant-specific mitigating actions designedmore » to reduce the probability of failure of a reactor vessel. 10 refs.« less

  20. Evaluation of Flexible Force Sensors for Pressure Monitoring in Treatment of Chronic Venous Disorders.

    PubMed

    Parmar, Suresh; Khodasevych, Iryna; Troynikov, Olga

    2017-08-21

    The recent use of graduated compression therapy for treatment of chronic venous disorders such as leg ulcers and oedema has led to considerable research interest in flexible and low-cost force sensors. Properly applied low pressure during compression therapy can substantially improve the treatment of chronic venous disorders. However, achievement of the recommended low pressure levels and its accurate determination in real-life conditions is still a challenge. Several thin and flexible force sensors, which can also function as pressure sensors, are commercially available, but their real-life sensing performance has not been evaluated. Moreover, no researchers have reported information on sensor performance during static and dynamic loading within the realistic test conditions required for compression therapy. This research investigated the sensing performance of five low-cost commercial pressure sensors on a human-leg-like test apparatus and presents quantitative results on the accuracy and drift behaviour of these sensors in both static and dynamic conditions required for compression therapy. Extensive experimental work on this new human-leg-like test setup demonstrated its utility for evaluating the sensors. Results showed variation in static and dynamic sensing performance, including accuracy and drift characteristics. Only one commercially available pressure sensor was found to reliably deliver accuracy of 95% and above for all three test pressure points of 30, 50 and 70 mmHg.

  1. Evaluation of Flexible Force Sensors for Pressure Monitoring in Treatment of Chronic Venous Disorders

    PubMed Central

    Parmar, Suresh; Khodasevych, Iryna; Troynikov, Olga

    2017-01-01

    The recent use of graduated compression therapy for treatment of chronic venous disorders such as leg ulcers and oedema has led to considerable research interest in flexible and low-cost force sensors. Properly applied low pressure during compression therapy can substantially improve the treatment of chronic venous disorders. However, achievement of the recommended low pressure levels and its accurate determination in real-life conditions is still a challenge. Several thin and flexible force sensors, which can also function as pressure sensors, are commercially available, but their real-life sensing performance has not been evaluated. Moreover, no researchers have reported information on sensor performance during static and dynamic loading within the realistic test conditions required for compression therapy. This research investigated the sensing performance of five low-cost commercial pressure sensors on a human-leg-like test apparatus and presents quantitative results on the accuracy and drift behaviour of these sensors in both static and dynamic conditions required for compression therapy. Extensive experimental work on this new human-leg-like test setup demonstrated its utility for evaluating the sensors. Results showed variation in static and dynamic sensing performance, including accuracy and drift characteristics. Only one commercially available pressure sensor was found to reliably deliver accuracy of 95% and above for all three test pressure points of 30, 50 and 70 mmHg. PMID:28825672

  2. Flight test evaluation of an RAF high altitude partial pressure protective assembly

    NASA Technical Reports Server (NTRS)

    Ashworth, G. R.; Putnam, T. W.; Dana, W. J.; Enevoldson, E. K.; Winter, W. R.

    1979-01-01

    A partial pressure suit was evaluated during tests in an F-104 and F-15 as a protective garment for emergency descents. The garment is an pressure jerkin and modified anti-g suit combined with an oronasal mask. The garment can be donned and doffed at the aircraft to minimize thermal buildup. The oronasal mask was favored by the pilots due to its immobility on the face during high g-loading. The garment was chosen to provide optimum dexterity for the pilot, which is not available in a full pressure suit, while protecting the pilot at altitudes up to 18,288 meters, during a cabin decompression, and subsequent aircraft descent. During cabin decompressions in the F-104 and F-15, cabin pressure altitude was measured at various aircraft angles of attack, Mach numbers, and altitudes to determine the effect of the aerodynamic slipstream on the cabin altitude.

  3. Solving the Fluid Pressure Poisson Equation Using Multigrid-Evaluation and Improvements.

    PubMed

    Dick, Christian; Rogowsky, Marcus; Westermann, Rudiger

    2016-11-01

    In many numerical simulations of fluids governed by the incompressible Navier-Stokes equations, the pressure Poisson equation needs to be solved to enforce mass conservation. Multigrid solvers show excellent convergence in simple scenarios, yet they can converge slowly in domains where physically separated regions are combined at coarser scales. Moreover, existing multigrid solvers are tailored to specific discretizations of the pressure Poisson equation, and they cannot easily be adapted to other discretizations. In this paper we analyze the convergence properties of existing multigrid solvers for the pressure Poisson equation in different simulation domains, and we show how to further improve the multigrid convergence rate by using a graph-based extension to determine the coarse grid hierarchy. The proposed multigrid solver is generic in that it can be applied to different kinds of discretizations of the pressure Poisson equation, by using solely the specification of the simulation domain and pre-assembled computational stencils. We analyze the proposed solver in combination with finite difference and finite volume discretizations of the pressure Poisson equation. Our evaluations show that, despite the common assumption, multigrid schemes can exploit their potential even in the most complicated simulation scenarios, yet this behavior is obtained at the price of higher memory consumption.

  4. Performance of fuselage pressure structure

    NASA Technical Reports Server (NTRS)

    Maclin, James R.

    1992-01-01

    There are currently more than 1,000 Boeing airplanes around the world over 20 years old. That number is expected to double by the year 1995. With these statistics comes the reality that structural airworthiness will be in the forefront of aviation issues well into the next century. The results of previous and recent test programs Boeing has implemented to study the structural performance of older airplanes relative to pressurized fuselage sections are described. Included in testing were flat panels with multiple site damage (MSD), a full-scale 737 and 2 747s as well as panels representing a 737 and 777, and a generic aircraft in large pressure-test fixtures. Because damage is a normal part of aging, focus is on the degree to which structural integrity is maintained after failure or partial failure of any structural element, including multiple site damage (MSD), and multiple element damage (MED).

  5. Debonding Stress Concentrations in a Pressurized Lobed Sandwich-Walled Generic Cryogenic Tank

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    2004-01-01

    A finite-element stress analysis has been conducted on a lobed composite sandwich tank subjected to internal pressure and cryogenic cooling. The lobed geometry consists of two obtuse circular walls joined together with a common flat wall. Under internal pressure and cryogenic cooling, this type of lobed tank wall will experience open-mode (a process in which the honeycomb is stretched in the depth direction) and shear stress concentrations at the junctures where curved wall changes into flat wall (known as a curve-flat juncture). Open-mode and shear stress concentrations occur in the honeycomb core at the curve-flat junctures and could cause debonding failure. The levels of contributions from internal pressure and temperature loading to the open-mode and shear debonding failure are compared. The lobed fuel tank with honeycomb sandwich walls has been found to be a structurally unsound geometry because of very low debonding failure strengths. The debonding failure problem could be eliminated if the honeycomb core at the curve-flat juncture is replaced with a solid core.

  6. An FMEA evaluation of intensity modulated radiation therapy dose delivery failures at tolerance criteria levels.

    PubMed

    Faught, Jacqueline Tonigan; Balter, Peter A; Johnson, Jennifer L; Kry, Stephen F; Court, Laurence E; Stingo, Francesco C; Followill, David S

    2017-11-01

    scores positively correlated (P < 0.01) for each FM as expected. No universal correlations were found between the demographic information collected and scoring, percent dose errors or ranking. Failure modes investigated overall were evaluated as low to medium risk, with average RPNs less than 110. The ranking of 11 failure modes was not agreed upon by the community. Large variability in FMEA scoring may be caused by individual interpretation and/or experience, reflecting the subjective nature of the FMEA tool. © 2017 American Association of Physicists in Medicine.

  7. Is the area under blood pressure curve the best parameter to evaluate 24-h ambulatory blood pressure monitoring data?

    PubMed

    Nobre, Fernando; Mion, Décio

    2005-10-01

    Ambulatory blood pressure monitoring (ABPM) provides relevant data about blood pressure over a 24-h period. The analysis of parameters to determine the blood pressure profile from these data is of great importance. To calculate areas under systolic and diastolic blood pressure curves (SBP-AUC/DBP-AUC) and compare with systolic and diastolic blood pressure load (SBPL/DBPL) and 24-h systolic and diastolic blood pressure (24-h SBP/24-h DBP) in order to determine which provides the best correlation with left ventricular mass index (LVMI). ABPM measurements (1143 individuals) were analyzed to obtain 24-h SBP/24-h DBP, SBPL/DBPL, and SBP-AUC/ DBP-AUC, using Spacelabs (90207) and CardioSistemas devices. Left ventricular mass was determined using an echocardiograph HP Sonos 5500 and LVMI was calculated. The correlations between all possible pairs within the group 24-h SBP/SBPL/SBP-AUC and 24-h DBP/DBPL/DBP-AUC were high and statistically significant. The correlations between 24-h SBP/24-h DBP and SBP-AUC/DBP-AUC with SBPL/DBPL close to 100%, were lower than those mentioned above. The correlations of the parameters obtained by ABPM with LVMI were also high and statistically significant, except for blood pressure load between 90 and 100%, and for 24-h SBP of 135 mmHg or less and SBPL higher than 50%. SBPL/DBPL and SBP-AUC/DBP-AUC can be used for the evaluation of ABPM data owing to the strong correlation with 24-h SBP/24-h DBP and with LVMI, except when SBPL is close to 100% or 24-h SBP is below 135 mmHg but SBPL is above 50%. SBP-AUC/DBP-AUC, however, are a better alternative because they do not have the limitations of blood pressure load or even of 24-h blood pressure present.

  8. Rodent heart failure models do not reflect the human circulating microRNA signature in heart failure.

    PubMed

    Vegter, Eline L; Ovchinnikova, Ekaterina S; Silljé, Herman H W; Meems, Laura M G; van der Pol, Atze; van der Velde, A Rogier; Berezikov, Eugene; Voors, Adriaan A; de Boer, Rudolf A; van der Meer, Peter

    2017-01-01

    We recently identified a set of plasma microRNAs (miRNAs) that are downregulated in patients with heart failure in comparison with control subjects. To better understand their meaning and function, we sought to validate these circulating miRNAs in 3 different well-established rat and mouse heart failure models, and correlated the miRNAs to parameters of cardiac function. The previously identified let-7i-5p, miR-16-5p, miR-18a-5p, miR-26b-5p, miR-27a-3p, miR-30e-5p, miR-199a-3p, miR-223-3p, miR-423-3p, miR-423-5p and miR-652-3p were measured by means of quantitative real time polymerase chain reaction (qRT-PCR) in plasma samples of 8 homozygous TGR(mREN2)27 (Ren2) transgenic rats and 8 (control) Sprague-Dawley rats, 6 mice with angiotensin II-induced heart failure (AngII) and 6 control mice, and 8 mice with ischemic heart failure and 6 controls. Circulating miRNA levels were compared between the heart failure animals and healthy controls. Ren2 rats, AngII mice and mice with ischemic heart failure showed clear signs of heart failure, exemplified by increased left ventricular and lung weights, elevated end-diastolic left ventricular pressures, increased expression of cardiac stress markers and reduced left ventricular ejection fraction. All miRNAs were detectable in plasma from rats and mice. No significant differences were observed between the circulating miRNAs in heart failure animals when compared to the healthy controls (all P>0.05) and no robust associations with cardiac function could be found. The previous observation that miRNAs circulate in lower levels in human patients with heart failure could not be validated in well-established rat and mouse heart failure models. These results question the translation of data on human circulating miRNA levels to experimental models, and vice versa the validity of experimental miRNA data for human heart failure.

  9. Failure Progress of 3D Reinforced GFRP Laminate during Static Bending, Evaluated by Means of Acoustic Emission and Vibrations Analysis.

    PubMed

    Koziol, Mateusz; Figlus, Tomasz

    2015-12-14

    The work aimed to assess the failure progress in a glass fiber-reinforced polymer laminate with a 3D-woven and (as a comparison) plain-woven reinforcement, during static bending, using acoustic emission signals. The innovative method of the separation of the signal coming from the fiber fracture and the one coming from the matrix fracture with the use of the acoustic event's energy as a criterion was applied. The failure progress during static bending was alternatively analyzed by evaluation of the vibration signal. It gave a possibility to validate the results of the acoustic emission. Acoustic emission, as well as vibration signal analysis proved to be good and effective tools for the registration of failure effects in composite laminates. Vibration analysis is more complicated methodologically, yet it is more precise. The failure progress of the 3D laminate is "safer" and more beneficial than that of the plain-woven laminate. It exhibits less rapid load capacity drops and a higher fiber effort contribution at the moment of the main laminate failure.

  10. Gravity-driven groundwater flow and slope failure potential: 1. Elastic effective-stress model

    USGS Publications Warehouse

    Iverson, Richard M.; Reid, Mark E.

    1992-01-01

    Hilly or mountainous topography influences gravity-driven groundwater flow and the consequent distribution of effective stress in shallow subsurface environments. Effective stress, in turn, influences the potential for slope failure. To evaluate these influences, we formulate a two-dimensional, steady state, poroelastic model. The governing equations incorporate groundwater effects as body forces, and they demonstrate that spatially uniform pore pressure changes do not influence effective stresses. We implement the model using two finite element codes. As an illustrative case, we calculate the groundwater flow field, total body force field, and effective stress field in a straight, homogeneous hillslope. The total body force and effective stress fields show that groundwater flow can influence shear stresses as well as effective normal stresses. In most parts of the hillslope, groundwater flow significantly increases the Coulomb failure potential Φ, which we define as the ratio of maximum shear stress to mean effective normal stress. Groundwater flow also shifts the locus of greatest failure potential toward the slope toe. However, the effects of groundwater flow on failure potential are less pronounced than might be anticipated on the basis of a simpler, one-dimensional, limit equilibrium analysis. This is a consequence of continuity, compatibility, and boundary constraints on the two-dimensional flow and stress fields, and it points to important differences between our elastic continuum model and limit equilibrium models commonly used to assess slope stability.

  11. Controls on shallow landslide initiation: Diverse hydrologic pathways, 3D failure geometries, and unsaturated soil suctions

    NASA Astrophysics Data System (ADS)

    Reid, Mark; Iverson, Richard; Brien, Dianne; Iverson, Neal; LaHusen, Richard; Logan, Matthew

    2017-04-01

    Shallow landslides and ensuing debris flows are a common hazard worldwide, yet forecasting their initiation at a specific site is challenging. These challenges arise, in part, from diverse near-surface hydrologic pathways under different wetting conditions, 3D failure geometries, and the effects of suction in partially saturated soils. Simplistic hydrologic models typically used for regional hazard assessment disregard these complexities. As an alterative to field studies where the effects of these governing factors can be difficult to isolate, we used the USGS debris-flow flume to conduct controlled, field-scale landslide initiation experiments. Using overhead sprinklers or groundwater injectors on the flume bed, we triggered failures using three different wetting conditions: groundwater inflow from below, prolonged moderate-intensity precipitation, and bursts of high-intensity precipitation. Failures occurred in 6 m3 (0.65-m thick and 2-m wide) prisms of loamy sand on a 31° slope; these field-scale failures enabled realistic incorporation of nonlinear scale-dependent effects such as soil suction. During the experiments, we monitored soil deformation, variably saturated pore pressures, and moisture changes using ˜50 sensors sampling at 20 Hz. From ancillary laboratory tests, we determined shear strength, saturated hydraulic conductivities, and unsaturated moisture retention characteristics. The three different wetting conditions noted above led to different hydrologic pathways and influenced instrumental responses and failure timing. During groundwater injection, pore-water pressures increased from the bed of the flume upwards into the sediment, whereas prolonged moderate infiltration wet the sediment from the ground surface downward. In both cases, pore pressures acting on the impending failure surface slowly rose until abrupt failure. In contrast, a burst of intense sprinkling caused rapid failure without precursory development of widespread positive pore

  12. Detecting the transition to failure: wavelet analysis of multi-scale crack patterns at different confining pressures

    NASA Astrophysics Data System (ADS)

    Rizzo, R. E.; Healy, D.; Farrell, N. J.

    2017-12-01

    Numerous laboratory brittle deformation experiments have shown that a rapid transition exists in the behaviour of porous materials under stress: at a certain point, early formed tensile cracks interact and coalesce into a `single' narrow zone, the shear plane, rather than remaining distributed throughout the material. In this work, we present and apply a novel image processing tool which is able to quantify this transition between distributed (`stable') damage accumulation and localised (`unstable') deformation, in terms of size, density, and orientation of cracks at the point of failure. Our technique, based on a two-dimensional (2D) continuous Morlet wavelet analysis, can recognise, extract and visually separate the multi-scale changes occurring in the fracture network during the deformation process. We have analysed high-resolution SEM-BSE images of thin sections of Hopeman Sandstone (Scotland, UK) taken from core plugs deformed under triaxial conditions, with increasing confining pressure. Through this analysis, we can determine the relationship between the initial orientation of tensile microcracks and the final geometry of the through-going shear fault, exploiting the total areal coverage of the analysed image. In addition, by comparing patterns of fractures in thin sections derived from triaxial (σ1>σ2=σ3=Pc) laboratory experiments conducted at different confining pressures (Pc), we can quantitatively explore the relationship between the observed geometry and the inferred mechanical processes. The methodology presented here can have important implications for larger-scale mechanical problems related to major fault propagation. Just as a core plug scale fault localises through extension and coalescence of microcracks, larger faults also grow by extension and coalescence of segments in a multi-scale process by which microscopic cracks can ultimately lead to macroscopic faulting. Consequently, wavelet analysis represents a useful tool for fracture pattern

  13. A program to evaluate a control system based on feedback of aerodynamic pressure differentials

    NASA Technical Reports Server (NTRS)

    Levy, D. W.; Finn, P.; Roskam, J.

    1981-01-01

    The use of aerodynamic pressure differentials to position a control surface is evaluated. The system is a differential pressure command loop, analogous to a position command loop, where the surface is commanded to move until a desired differential pressure across the surface is achieved. This type of control is more direct and accurate because it is the differential pressure which causes the control forces and moments. A frequency response test was performed in a low speed wind tunnel to measure the performance of the system. Both pressure and position feedback were tested. The pressure feedback performed as well as position feedback implying that the actuator, with a break frequency on the order of 10 Rad/sec, was the limiting component. Theoretical considerations indicate that aerodynamic lags will not appear below frequencies of 50 Rad/sec, or higher.

  14. Patient engagement with a mobile web-based telemonitoring system for heart failure self-management: a pilot study.

    PubMed

    Zan, Shiyi; Agboola, Stephen; Moore, Stephanie A; Parks, Kimberly A; Kvedar, Joseph C; Jethwani, Kamal

    2015-04-01

    Intensive remote monitoring programs for congestive heart failure have been successful in reducing costly readmissions, but may not be appropriate for all patients. There is an opportunity to leverage the increasing accessibility of mobile technologies and consumer-facing digital devices to empower patients in monitoring their own health outside of the hospital setting. The iGetBetter system, a secure Web- and telephone-based heart failure remote monitoring program, which leverages mobile technology and portable digital devices, offers a creative solution at lower cost. The objective of this pilot study was to evaluate the feasibility of using the iGetBetter system for disease self-management in patients with heart failure. This was a single-arm prospective study in which 21 ambulatory, adult heart failure patients used the intervention for heart failure self-management over a 90-day study period. Patients were instructed to take their weight, blood pressure, and heart rate measurements each morning using a WS-30 bluetooth weight scale, a self-inflating blood pressure cuff (Withings LLC, Issy les Moulineaux, France), and an iPad Mini tablet computer (Apple Inc, Cupertino, CA, USA) equipped with cellular Internet connectivity to view their measurements on the Internet. Outcomes assessed included usability and satisfaction, engagement with the intervention, hospital resource utilization, and heart failure-related quality of life. Descriptive statistics were used to summarize data, and matched controls identified from the electronic medical record were used as comparison for evaluating hospitalizations. There were 20 participants (mean age 53 years) that completed the study. Almost all participants (19/20, 95%) reported feeling more connected to their health care team and more confident in performing care plan activities, and 18/20 (90%) felt better prepared to start discussions about their health with their doctor. Although heart failure-related quality of life

  15. High-throughput sequencing: a failure mode analysis.

    PubMed

    Yang, George S; Stott, Jeffery M; Smailus, Duane; Barber, Sarah A; Balasundaram, Miruna; Marra, Marco A; Holt, Robert A

    2005-01-04

    Basic manufacturing principles are becoming increasingly important in high-throughput sequencing facilities where there is a constant drive to increase quality, increase efficiency, and decrease operating costs. While high-throughput centres report failure rates typically on the order of 10%, the causes of sporadic sequencing failures are seldom analyzed in detail and have not, in the past, been formally reported. Here we report the results of a failure mode analysis of our production sequencing facility based on detailed evaluation of 9,216 ESTs generated from two cDNA libraries. Two categories of failures are described; process-related failures (failures due to equipment or sample handling) and template-related failures (failures that are revealed by close inspection of electropherograms and are likely due to properties of the template DNA sequence itself). Preventative action based on a detailed understanding of failure modes is likely to improve the performance of other production sequencing pipelines.

  16. Baseline Blood Pressure, the 2017 ACC/AHA High Blood Pressure Guidelines, and Long-Term Cardiovascular Risk in SPRINT.

    PubMed

    Vaduganathan, Muthiah; Pareek, Manan; Qamar, Arman; Pandey, Ambarish; Olsen, Michael H; Bhatt, Deepak L

    2018-02-05

    The 2017 American College of Cardiology (ACC)/American Heart Association (AHA) guidelines include lower thresholds to define hypertension than previous guidelines. Little is known about the impact of these guideline changes in patients with or at high risk for cardiovascular disease. In this exploratory analysis using baseline blood pressure assessments in Systolic Blood Pressure Intervention Trial (SPRINT), we evaluated the prevalence and associated cardiovascular prognosis of patients newly reclassified with hypertension based on the 2017 ACC/AHA (systolic blood pressure ≥130 mm Hg or diastolic blood pressure ≥80 mm Hg) compared with the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC 7) guidelines (systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg). The primary endpoint was the composite of myocardial infarction, other acute coronary syndromes, stroke, heart failure, or cardiovascular death. In 4683 patients assigned to the standard treatment arm of SPRINT, 2328 (49.7%) met hypertension thresholds by JNC 7 guidelines, and another 1424 (30.4%) were newly reclassified as having hypertension based on the 2017 ACC/AHA guidelines. Over 3.3-year median follow-up, 319 patients experienced the primary endpoint (87 of whom were newly reclassified with hypertension based on the revised guidelines). Patients with hypertension based on prior guidelines compared with those newly identified with hypertension based on the new guidelines had similar risk of the primary endpoint (2.3 [95% confidence interval {CI}, 2.0-2.7] vs 2.0 [95% CI, 1.6-2.4] events per 100 patient-years; adjusted HR, 1.10 [95% CI, 0.84-1.44]; P = .48). The 2017 ACC/AHA high blood pressure guidelines are expected to significantly increase the prevalence of patients with hypertension (perhaps to a greater extent in higher-risk patient cohorts compared with the general population) and

  17. Conduit Stability and Collapse in Explosive Volcanic Eruptions: Coupling Conduit Flow and Failure Models

    NASA Astrophysics Data System (ADS)

    Mullet, B.; Segall, P.

    2017-12-01

    Explosive volcanic eruptions can exhibit abrupt changes in physical behavior. In the most extreme cases, high rates of mass discharge are interspaced by dramatic drops in activity and periods of quiescence. Simple models predict exponential decay in magma chamber pressure, leading to a gradual tapering of eruptive flux. Abrupt changes in eruptive flux therefore indicate that relief of chamber pressure cannot be the only control of the evolution of such eruptions. We present a simplified physics-based model of conduit flow during an explosive volcanic eruption that attempts to predict stress-induced conduit collapse linked to co-eruptive pressure loss. The model couples a simple two phase (gas-melt) 1-D conduit solution of the continuity and momentum equations with a Mohr-Coulomb failure condition for the conduit wall rock. First order models of volatile exsolution (i.e. phase mass transfer) and fragmentation are incorporated. The interphase interaction force changes dramatically between flow regimes, so smoothing of this force is critical for realistic results. Reductions in the interphase force lead to significant relative phase velocities, highlighting the deficiency of homogenous flow models. Lateral gas loss through conduit walls is incorporated using a membrane-diffusion model with depth dependent wall rock permeability. Rapid eruptive flux results in a decrease of chamber and conduit pressure, which leads to a critical deviatoric stress condition at the conduit wall. Analogous stress distributions have been analyzed for wellbores, where much work has been directed at determining conditions that lead to wellbore failure using Mohr-Coulomb failure theory. We extend this framework to cylindrical volcanic conduits, where large deviatoric stresses can develop co-eruptively leading to multiple distinct failure regimes depending on principal stress orientations. These failure regimes are categorized and possible implications for conduit flow are discussed, including

  18. SPECT and PET in ischemic heart failure.

    PubMed

    Angelidis, George; Giamouzis, Gregory; Karagiannis, Georgios; Butler, Javed; Tsougos, Ioannis; Valotassiou, Varvara; Giannakoulas, George; Dimakopoulos, Nikolaos; Xanthopoulos, Andrew; Skoularigis, John; Triposkiadis, Filippos; Georgoulias, Panagiotis

    2017-03-01

    Heart failure is a common clinical syndrome associated with significant morbidity and mortality worldwide. Ischemic heart disease is the leading cause of heart failure, at least in the industrialized countries. Proper diagnosis of the syndrome and management of patients with heart failure require anatomical and functional information obtained through various imaging modalities. Nuclear cardiology techniques play a main role in the evaluation of heart failure. Myocardial single photon emission computed tomography (SPECT) with thallium-201 or technetium-99 m labelled tracers offer valuable data regarding ventricular function, myocardial perfusion, viability, and intraventricular synchronism. Moreover, positron emission tomography (PET) permits accurate evaluation of myocardial perfusion, metabolism, and viability, providing high-quality images and the ability of quantitative analysis. As these imaging techniques assess different parameters of cardiac structure and function, variations of sensitivity and specificity have been reported among them. In addition, the role of SPECT and PET guided therapy remains controversial. In this comprehensive review, we address these controversies and report the advances in patient's investigation with SPECT and PET in ischemic heart failure. Furthermore, we present the innovations in technology that are expected to strengthen the role of nuclear cardiology modalities in the investigation of heart failure.

  19. Automatic method for evaluating the activity of sourdough strains based on gas pressure measurements.

    PubMed

    Wick, M; Vanhoutte, J J; Adhemard, A; Turini, G; Lebeault, J M

    2001-04-01

    A new method is proposed for the evaluation of the activity of sourdough strains, based on gas pressure measurements in closed air-tight reactors. Gas pressure and pH were monitored on-line during the cultivation of commercial yeasts and heterofermentative lactic acid bacteria on a semi-synthetic medium with glucose as the major carbon source. Relative gas pressure evolution was compared both to glucose consumption and to acidification and growth. It became obvious that gas pressure evolution is related to glucose consumption kinetics. For each strain, a correlation was made between maximum gas pressure variation and amount of glucose consumed. The mass balance of CO2 in both liquid and gas phase demonstrated that around 90% of CO2 was recovered. Concerning biomass production, a linear relationship was found between log colony-forming units/ml and log pressure for both yeasts and bacteria during the exponential phase; and for yeasts, relative gas pressure evolution also followed optical density variation.

  20. Design Against Propagating Shear Failure in Pipelines

    NASA Astrophysics Data System (ADS)

    Leis, B. N.; Gray, J. Malcolm

    Propagating shear failure can occur in gas and certain hazardous liquid transmission pipelines, potentially leading to a large long-burning fire and/or widespread pollution, depending on the transported product. Such consequences require that the design of the pipeline and specification of the steel effectively preclude the chance of propagating shear failure. Because the phenomenology of such failures is complex, design against such occurrences historically has relied on full-scale demonstration experiments coupled with empirically calibrated analytical models. However, as economic drivers have pushed toward larger diameter higher pressure pipelines made of tough higher-strength grades, the design basis to ensure arrest has been severely compromised. Accordingly, for applications where the design basis becomes less certain, as has occurred increasing as steel grade and toughness has increased, it has become necessary to place greater reliance on the use and role of full-scale testing.

  1. Pressure-Relief Features of Fixed and Autotitrating Continuous Positive Airway Pressure May Impair Their Efficacy: Evaluation with a Respiratory Bench Model

    PubMed Central

    Zhu, Kaixian; Aouf, Sami; Roisman, Gabriel; Escourrou, Pierre

    2016-01-01

    , Roisman G, Escourrou P. Pressure-relief features of fixed and autotitrating continuous positive airway pressure may impair their efficacy: evaluation with a respiratory bench model. J Clin Sleep Med 2016;12(3):385–392. PMID:26564383

  2. Nonsteroidal anti-inflammatory drugs-induced failure of lower esophageal and pyloric sphincter and counteraction of sphincters failure with stable gatric pentadecapeptide BPC 157 in rats.

    PubMed

    Vitaic, S; Stupnisek, M; Drmic, D; Bauk, L; Kokot, A; Klicek, R; Vcev, A; Luetic, K; Seiwerth, S; Sikiric, P

    2017-04-01

    The sphincters failure is a part of NSAIDs-toxicity that can be accordingly counteracted. We used a safe stable gastric pentadecapeptide BPC 157 (GEPPPGKPADDAGLV, MW 1419), LD1 not achieved, since successful in inflammatory bowel disease trials, and counteracts esophagitis, sphincters failure, gastrointestinal ulcer and skin ulcer, external and internal fistulas in rats, and particularly counteracts all NSAIDs-lesions. We assessed lower esophageal sphincter and pyloric sphincter pressure (cmH 2 O) in rats treated with various NSAIDs regimens, at corresponding time points, known to produce stomach, small intestine lesions, hepatotoxicity and encephalopathy. Assessment was after diclofenac (12.5 mg/kg, 40 mg/kg intraperitoneal challenge), ibuprofen (400 mg/day/kg intraperitoneally for 4 weeks), paracetamol (5.0 g/kg intraperitoneal challenge), aspirin (400 mg/kg intraperitoneally or intragastrically), celecoxib (0.5 mg/kg, 1.0 mg/kg intraperitoneally). BPC 157 (10 μg/kg, 10 ng/kg) was given immediately after NSAIDs (intraperitoneally or intragastrically) or given in drinking water. Regularly, in all control NSAIDs fall of pressure occurred in both sphincters rapidly and then persisted. By contrast, in all NSAIDs-rats that received BPC 157, initial fall of pressure was minimized and pressure values restored to normal values. All tested NSAIDs decrease pressure in both sphincters, whilst BPC 157 counteracts their effects and restored both sphincters function.

  3. Failure Analysis of PRDS Pipe in a Thermal Power Plant Boiler

    NASA Astrophysics Data System (ADS)

    Ghosh, Debashis; Ray, Subrata; Mandal, Jiten; Mandal, Nilrudra; Shukla, Awdhesh Kumar

    2018-04-01

    The pressure reducer desuperheater (PRDS) pipeline is used for reducing the pressure and desuperheating of the steam in different auxiliary pipeline. When the PRDS pipeline is failed, the reliability of the boiler is affected. This paper investigates the probable cause/causes of failure of the PRDS tapping line. In that context, visual inspection, outside diameter and wall thickness measurement, chemical analysis, metallographic examination and hardness measurement are conducted as part of the investigative studies. Apart from these tests, mechanical testing and fractographic analysis are also conducted as supplements. Finally, it has been concluded that the PRDS pipeline has mainly failed due to graphitization due to prolonged exposure of the pipe at higher temperature. The improper material used is mainly responsible for premature failure of the pipe.

  4. Role of Copper and Homocysteine in Pressure Overload Heart Failure

    PubMed Central

    Hughes, William M.; Rodriguez, Walter E.; Rosenberger, Dorothea; Chen, Jing; Sen, Utpal; Tyagi, Neetu; Moshal, Karni S.; Vacek, Thomas; Kang, Y. James

    2009-01-01

    Elevated levels of homocysteine (Hcy) (known as hyperhomocysteinemia HHcy) are involved in dilated cardiomyopathy. Hcy chelates copper and impairs copper-dependent enzymes. Copper deficiency has been linked to cardiovascular disease. We tested the hypothesis that copper supplement regresses left ventricular hypertrophy (LVH), fibrosis and endothelial dysfunction in pressure overload DCM mice hearts. The mice were grouped as sham, sham + Cu, aortic constriction (AC), and AC + Cu. Aortic constriction was performed by transverse aortic constriction. The mice were treated with or without 20 mg/kg copper supplement in the diet for 12 weeks. The cardiac function was assessed by echocardiography and electrocardiography. The matrix remodeling was assessed by measuring matrix metalloproteinase (MMP), tissue inhibitor of metalloproteinases (TIMPs), and lysyl oxidase (LOX) by Western blot analyses. The results suggest that in AC mice, cardiac function was improved with copper supplement. TIMP-1 levels decreased in AC and were normalized in AC + Cu. Although MMP-9, TIMP-3, and LOX activity increased in AC and returned to baseline value in AC + Cu, copper supplement showed no significant effect on TIMP-4 activity after pressure overload. In conclusion, our data suggest that copper supplement helps improve cardiac function in a pressure overload dilated cardiomyopathic heart. PMID:18679830

  5. A modified Glenn shunt reduces venous congestion during acute right ventricular failure due to pulmonary banding: a randomized experimental study

    PubMed Central

    Vikholm, Per; Schiller, Petter; Hellgren, Laila

    2014-01-01

    OBJECTIVES Right ventricular failure after left ventricular assist device implantation is a serious complication with high rates of mortality and morbidity. It has been demonstrated in experimental settings that volume exclusion of the right ventricle with a modified Glenn shunt can improve haemodynamics during ischaemic right ventricular failure. However, the concept of a modified Glenn shunt is dependent on a normal pulmonary vascular resistance, which can limit its use in some patients. The aim of this study was to explore the effects of volume exclusion with a modified Glenn shunt during right ventricular failure due to pulmonary banding, and to study the alterations in genetic expression in the right ventricle due to pressure and volume overload. METHODS Experimental right ventricular failure was induced in pigs (n = 11) through 2 h of pulmonary banding. The pigs were randomized to either treatment with a modified Glenn shunt and pulmonary banding (n = 6) or solely pulmonary banding (n = 5) as a control group. Haemodynamic measurements, blood samples and right ventricular biopsies for genetic analysis were sampled at baseline, at right ventricular failure (i.e. 2 h of pulmonary banding) and 1 h post-right ventricular failure in both groups. RESULTS Right atrial pressure increased from 10 mmHg (9.0–12) to 18 mmHg (16–22) (P < 0.01) and the right ventricular pressure from 31 mmHg (26–35) to 57 mmHg (49–61) (P < 0.01) after pulmonary banding. Subsequent treatment with the modified Glenn shunt resulted in a decrease in right atrial pressure to 13 mmHg (11–14) (P = 0.03). In the control group, right atrial pressure was unchanged at 19 mmHg (16–20) (P = 0.18). At right heart failure, there was an up-regulation of genes associated with heart failure, inflammation, angiogenesis, negative regulation of cell death and proliferation. CONCLUSIONS Volume exclusion with a modified Glenn shunt during right ventricular failure reduced venous congestion compared

  6. Extracorporeal Respiratory Support With a Miniature Integrated Pediatric Pump-Lung Device in an Acute Ovine Respiratory Failure Model.

    PubMed

    Wei, Xufeng; Sanchez, Pablo G; Liu, Yang; Claire Watkins, A; Li, Tieluo; Griffith, Bartley P; Wu, Zhongjun J

    2016-11-01

    Respiratory failure is one of the major causes of mortality and morbidity all over the world. Therapeutic options to treat respiratory failure remain limited. The objective of this study was to evaluate the gas transfer performance of a newly developed miniature portable integrated pediatric pump-lung device (PediPL) with small membrane surface for respiratory support in an acute ovine respiratory failure model. The respiratory failure was created in six adult sheep using intravenous anesthesia and reduced mechanical ventilation at 2 breaths/min. The PediPL device was surgically implanted and evaluated for respiratory support in a venovenous configuration between the right atrium and pulmonary artery. The hemodynamics and respiratory status of the animals during support with the device gas transfer performance of the PediPL were studied for 4 h. The animals exhibited respiratory failure 30 min after mechanical ventilation was reduced to 2 breaths/min, indicated by low oxygen partial pressure, low oxygen saturation, and elevated carbon dioxide in arterial blood. The failure was reversed by establishing respiratory support with the PediPL after 30 min. The rates of O 2 transfer and CO 2 removal of the PediPL were 86.8 and 139.1 mL/min, respectively. The results demonstrated that the PediPL (miniature integrated pump-oxygenator) has the potential to provide respiratory support as a novel treatment for both hypoxia and hypercarbia. The compact size of the PediPL could allow portability and potentially be used in many emergency settings to rescue patients suffering acute lung injury. Copyright © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  7. Biomarkers in acute heart failure.

    PubMed

    Mallick, Aditi; Januzzi, James L

    2015-06-01

    The care of patients with acutely decompensated heart failure is being reshaped by the availability and understanding of several novel and emerging heart failure biomarkers. The gold standard biomarkers in heart failure are B-type natriuretic peptide and N-terminal pro-B-type natriuretic peptide, which play an important role in the diagnosis, prognosis, and management of acute decompensated heart failure. Novel biomarkers that are increasingly involved in the processes of myocardial injury, neurohormonal activation, and ventricular remodeling are showing promise in improving diagnosis and prognosis among patients with acute decompensated heart failure. These include midregional proatrial natriuretic peptide, soluble ST2, galectin-3, highly-sensitive troponin, and midregional proadrenomedullin. There has also been an emergence of biomarkers for evaluation of acute decompensated heart failure that assist in the differential diagnosis of dyspnea, such as procalcitonin (for identification of acute pneumonia), as well as markers that predict complications of acute decompensated heart failure, such as renal injury markers. In this article, we will review the pathophysiology and usefulness of established and emerging biomarkers for the clinical diagnosis, prognosis, and management of acute decompensated heart failure. Copyright © 2015 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  8. High pressure inactivation of relevant target microorganisms in poultry meat products and the evaluation of pressure-induced protein denaturation of marinated poultry under different high pressure treatments

    NASA Astrophysics Data System (ADS)

    Schmidgall, Johanna; Hertel, Christian; Bindrich, Ute; Heinz, Volker; Toepfl, Stefan

    2011-03-01

    In this study, the possibility of extending shelf life of marinated poultry meat products by high pressure processing was evaluated. Relevant spoilage and pathogenic strains were selected and used as target microorganisms (MOs) for challenge experiments. Meat and brine were inoculated with MOs and treated at 450 MPa, 4 °C for 3 min. The results of inactivation show a decreasing pressure tolerance in the series Lactobacillus > Arcobacter > Carnobacterium > Bacillus cereus > Brochothrix thermosphacta > Listeria monocytogenes. Leuconostoc gelidum exhibited the highest pressure tolerance in meat. A protective effect of poultry meat was found for L. sakei and L. gelidum. In parallel, the influence of different marinade formulations (pH, carbonates, citrates) on protein structure changes during a pressure treatment was investigated. Addition of sodium carbonate shows a protection against denaturation of myofibrillar proteins and provides a maximum water-holding capacity. Caustic marinades allowed a higher retention of product characteristics than low-pH marinades.

  9. On-Board Particulate Filter Failure Prevention and Failure Diagnostics Using Radio Frequency Sensing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sappok, Alex; Ragaller, Paul; Herman, Andrew

    The increasing use of diesel and gasoline particulate filters requires advanced on-board diagnostics (OBD) to prevent and detect filter failures and malfunctions. Early detection of upstream (engine-out) malfunctions is paramount to preventing irreversible damage to downstream aftertreatment system components. Such early detection can mitigate the failure of the particulate filter resulting in the escape of emissions exceeding permissible limits and extend the component life. However, despite best efforts at early detection and filter failure prevention, the OBD system must also be able to detect filter failures when they occur. In this study, radio frequency (RF) sensors were used to directlymore » monitor the particulate filter state of health for both gasoline particulate filter (GPF) and diesel particulate filter (DPF) applications. The testing included controlled engine dynamometer evaluations, which characterized soot slip from various filter failure modes, as well as on-road fleet vehicle tests. The results show a high sensitivity to detect conditions resulting in soot leakage from the particulate filter, as well as potential for direct detection of structural failures including internal cracks and melted regions within the filter media itself. Furthermore, the measurements demonstrate, for the first time, the capability to employ a direct and continuous monitor of particulate filter diagnostics to both prevent and detect potential failure conditions in the field.« less

  10. An analysis of policy success and failure in formal evaluations of Australia's national mental health strategy (1992-2012).

    PubMed

    Grace, Francesca C; Meurk, Carla S; Head, Brian W; Hall, Wayne D; Harris, Meredith G; Whiteford, Harvey A

    2017-05-30

    Heightened fiscal constraints, increases in the chronic disease burden and in consumer expectations are among several factors contributing to the global interest in evidence-informed health policy. The present article builds on previous work that explored how the Australian Federal Government applied five instruments of policy, or policy levers, to implement a series of reforms under the Australian National Mental Health Strategy (NMHS). The present article draws on theoretical insights from political science to analyse the relative successes and failures of these levers, as portrayed in formal government evaluations of the NMHS. Documentary analysis of six evaluation documents corresponding to three National Mental Health Plans was undertaken. Both the content and approach of these government-funded, independently conducted evaluations were appraised. An overall improvement was apparent in the development and application of policy levers over time. However, this finding should be interpreted with caution due to variations in evaluation approach according to Plan and policy lever. Tabulated summaries of the success and failure of each policy initiative, ordered by lever type, are provided to establish a resource that could be consulted for future policy-making. This analysis highlights the complexities of health service reform and underscores the limitations of narrowly focused empirical approaches. A theoretical framework is provided that could inform the evaluation and targeted selection of appropriate policy levers in mental health.

  11. Severity of nocturnal hypoxia and daytime hypercapnia predicts CPAP failure in patients with COPD and obstructive sleep apnea overlap syndrome.

    PubMed

    Kuklisova, Zuzana; Tkacova, Ruzena; Joppa, Pavol; Wouters, Emiel; Sastry, Manuel

    2017-02-01

    Obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) are independent risk factors for cardiovascular diseases. In patients with OSA and concurrent COPD, continuous positive airway pressure (CPAP) therapy improves survival. Nevertheless, a significant proportion of such patients do not tolerate CPAP. The aim of the present study was to analyze early predictors of CPAP failure in patients with OSA and concurrent COPD, and to evaluate the effects of bilevel positive airway pressure (BiPAP) in this high-risk group of patients. A post hoc analysis from the database of 2100 patients diagnosed with OSA between 2012 and 2014 identified 84 subjects as having concomitant COPD and meeting inclusion criteria. Demographic data, pulmonary function tests, OSA parameters, blood gases, response to CPAP and BiPAP titration, and two months of therapy were collected. A multivariate model was generated to find determinants of CPAP failure. Primary CPAP failure was found in 23% of patients who were more obese (p = 0.018), had worse lung function, lower PO 2 (p = 0.023) and higher PCO 2 while awake (p < 0.001), and more sleep time with an SpO 2  < 90% (CT90%) (p < 0.001) compared to those who responded to CPAP. In multivariate analysis, PCO 2 while awake [odds ratio (OR) 29.5, confidence interval (CI) 2.22-391, p = 0.010] and CT90% (OR 1.06, CI 1.01-1.11, p = 0.017) independently predicted CPAP failure after adjustments for covariates. The BiPAP therapy was well tolerated and effectively alleviated hypercapnia in all patients with primary CPAP failure. Daytime hypercapnia and nocturnal hypoxia are independent predictors of early CPAP failure in patients with the OSA-COPD overlap syndrome. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Lungs in Heart Failure

    PubMed Central

    Apostolo, Anna; Giusti, Giuliano; Gargiulo, Paola; Bussotti, Maurizio; Agostoni, Piergiuseppe

    2012-01-01

    Lung function abnormalities both at rest and during exercise are frequently observed in patients with chronic heart failure, also in the absence of respiratory disease. Alterations of respiratory mechanics and of gas exchange capacity are strictly related to heart failure. Severe heart failure patients often show a restrictive respiratory pattern, secondary to heart enlargement and increased lung fluids, and impairment of alveolar-capillary gas diffusion, mainly due to an increased resistance to molecular diffusion across the alveolar capillary membrane. Reduced gas diffusion contributes to exercise intolerance and to a worse prognosis. Cardiopulmonary exercise test is considered the “gold standard” when studying the cardiovascular, pulmonary, and metabolic adaptations to exercise in cardiac patients. During exercise, hyperventilation and consequent reduction of ventilation efficiency are often observed in heart failure patients, resulting in an increased slope of ventilation/carbon dioxide (VE/VCO2) relationship. Ventilatory efficiency is as strong prognostic and an important stratification marker. This paper describes the pulmonary abnormalities at rest and during exercise in the patients with heart failure, highlighting the principal diagnostic tools for evaluation of lungs function, the possible pharmacological interventions, and the parameters that could be useful in prognostic assessment of heart failure patients. PMID:23365739

  13. Experimental validation of Critical Temperature-Pressure theory of scuffing

    NASA Astrophysics Data System (ADS)

    Lee, Si C.; Chen, Huanliang

    1995-07-01

    A series of experiments was conducted for validating a newly developed theory of scuffing. The Critical temperature-Pressure (CTP) theory is based on the physisorption behavior of lubricants and is capable of predicting the onset of scuffing failures over a wide range of operating conditions, including the contacts operating in the boundary lubrication and in the partial elastohydrodynamic lubrication (EHL) regimes. According to the CTP theory, failures occur when the contact temperature exceeds a certain critical value which is a function of the lubricant pressure generated by the hydrodynamic action of the EHL contact. A special device capable of simulating the ambient conditions of the partial EHL conjunctions (of contact temperature, pressure, and the lubricant pressure) was constructed. A ball-on-flat type wear tester was put inside a pressure vessel, completely immersed in a highly pressurized bath of mineral oil. The temperature on the flat specimen was gradually increased while the ball was slowly traversed. At a certain critical temmperature, the friction force abruptly jumped indicating the incipiency of the lubrication breakdown. This experiment was repeated for several levels of hydrostatic pressure and the corresponding critical temperatures were obtained. The test results showed an excellent correlation with the newly developed CTP theory.

  14. Management of Sleep Disordered Breathing in Patients with Heart Failure.

    PubMed

    Oates, Connor P; Ananthram, Manjula; Gottlieb, Stephen S

    2018-06-01

    This paper reviews treatment options for sleep disordered breathing (SDB) in patients with heart failure. We sought to identify therapies for SDB with the best evidence for long-term use in patients with heart failure and to minimize uncertainties in clinical practice by examining frequently discussed questions: what is the role of continuous positive airway pressure (CPAP) in patients with heart failure? Is adaptive servo-ventilation (ASV) safe in patients with heart failure? To what extent is SDB a modifiable risk factor? Consistent evidence has demonstrated that the development of SDB in patients with heart failure is a poor prognostic indicator and a risk factor for cardiovascular mortality. However, despite numerous available interventions for obstructive sleep apnea and central sleep apnea, it remains unclear what effect these therapies have on patients with heart failure. To date, all major randomized clinical trials have failed to demonstrate a survival benefit with SDB therapy and one major study investigating the use of adaptive servo-ventilation demonstrated harm. Significant questions persist regarding the management of SDB in patients with heart failure. Until appropriately powered trials identify a treatment modality that increases cardiovascular survival in patients with SDB and heart failure, a patient's heart failure management should remain the priority of medical care.

  15. Evaluation of the Sierra, hanging, quick-don, crew, pressure-breathing, oxygen mask.

    DOT National Transportation Integrated Search

    1966-06-01

    A new design, hanging, quick-don crew pressure breathing oxygen mask applicable to jet-transport operations was tested and evaluated in three phases, consisting of (1) exposing five masked subjects to a stepwise altitude-chamber flight profile with a...

  16. Malnutrition and Cachexia in Heart Failure.

    PubMed

    Rahman, Adam; Jafry, Syed; Jeejeebhoy, Khursheed; Nagpal, A Dave; Pisani, Barbara; Agarwala, Ravi

    2016-05-01

    Heart failure is a growing public health concern. Advanced heart failure is frequently associated with severe muscle wasting, termed cardiac cachexia This process is driven by systemic inflammation and tumor necrosis factor in a manner common to other forms of disease-related wasting seen with cancer or human immunodeficiency virus. A variable degree of malnutrition is often superimposed from poor nutrient intake. Cardiac cachexia significantly decreases quality of life and survival in patients with heart failure. This review outlines the evaluation of nutrition status in heart failure, explores the pathophysiology of cardiac cachexia, and discusses therapeutic interventions targeting wasting in these patients. © 2015 American Society for Parenteral and Enteral Nutrition.

  17. Randomized controlled trial comparing nasal intermittent positive pressure ventilation and nasal continuous positive airway pressure in premature infants after tracheal extubation.

    PubMed

    Komatsu, Daniela Franco Rizzo; Diniz, Edna Maria de Albuquerque; Ferraro, Alexandre Archanjo; Ceccon, Maria Esther Jurvest Rivero; Vaz, Flávio Adolfo Costa

    2016-09-01

    To analyze the frequency of extubation failure in premature infants using conventional mechanical ventilation (MV) after extubation in groups subjected to nasal intermittent positive pressure ventilation (nIPPV) and continuous positive airway pressure (nCPAP). Seventy-two premature infants with respiratory failure were studied, with a gestational age (GA) ≤ 36 weeks and birth weight (BW) > 750 g, who required tracheal intubation and mechanical ventilation. The study was controlled and randomized in order to ensure that the members of the groups used in the research were chosen at random. Randomization was performed at the time of extubation using sealed envelopes. Extubation failure was defined as the need for re-intubation and mechanical ventilation during the first 72 hours after extubation. Among the 36 premature infants randomized to nIPPV, six (16.6%) presented extubation failure in comparison to 11 (30.5%) of the 36 premature infants randomized to nCPAP. There was no statistical difference between the two study groups regarding BW, GA, classification of the premature infant, and MV time. The main cause of extubation failure was the occurrence of apnea. Gastrointestinal and neurological complications did not occur in the premature infants participating in the study. We found that, despite the extubation failure of the group of premature infants submitted to nIPPV being numerically smaller than in premature infants submitted to nCPAP, there was no statistically significant difference between the two modes of ventilatory support after extubation.

  18. A program to evaluate a control system based on feedback of aerodynamic pressure differentials, part 1

    NASA Technical Reports Server (NTRS)

    Hrabak, R. R.; Levy, D. W.; Finn, P.; Roskam, J.

    1981-01-01

    The use of pressure differentials in a flight control system was evaluated. The pressure profile around the test surface was determined using two techniques: (1) windtunnel data (actual); and (2) NASA/Langley Single Element Airfoil Computer Program (theoretical). The system designed to evaluate the concept of using pressure differentials is composed of a sensor drive and power amplifiers, actuator, position potentiometer, and a control surface. The characteristics (both desired and actual) of the system and each individual component were analyzed. The desired characteristics of the system as a whole are given. The flight control system developed, the testing procedures and data reduction methods used, and theoretical frequency response analysis are described.

  19. Adverse Outcomes after Major Surgery in Patients with Pressure Ulcer: A Nationwide Population-Based Retrospective Cohort Study

    PubMed Central

    Chou, Chia-Lun; Lee, Woan-Ruoh; Yeh, Chun-Chieh; Shih, Chun-Chuan

    2015-01-01

    Background Postoperative adverse outcomes in patients with pressure ulcer are not completely understood. This study evaluated the association between preoperative pressure ulcer and adverse events after major surgeries. Methods Using reimbursement claims from Taiwan’s National Health Insurance Research Database, we conducted a nationwide retrospective cohort study of 17391 patients with preoperative pressure ulcer receiving major surgery in 2008-2010. With a propensity score matching procedure, 17391 surgical patients without pressure ulcer were selected for comparison. Eight major surgical postoperative complications and 30-day postoperative mortality were evaluated among patients with pressure ulcer of varying severity. Results Patients with preoperative pressure ulcer had significantly higher risk than controls for postoperative adverse outcomes, including septicemia, pneumonia, stroke, urinary tract infection, and acute renal failure. Surgical patients with pressure ulcer had approximately 1.83-fold risk (95% confidence interval 1.54-2.18) of 30-day postoperative mortality compared with control group. The most significant postoperative mortality was found in those with serious pressure ulcer, such as pressure ulcer with local infection, cellulitis, wound or treatment by change dressing, hospitalized care, debridement or antibiotics. Prolonged hospital or intensive care unit stay and increased medical expenditures were also associated with preoperative pressure ulcer. Conclusion This nationwide propensity score-matched retrospective cohort study showed increased postoperative complications and mortality in patients with preoperative pressure ulcer. Our findings suggest the urgency of preventing and managing preoperative pressure ulcer by a multidisciplinary medical team for this specific population. PMID:26000606

  20. Evaluation of the Present-on-Admission Indicator among Hospitalized Fee-for-Service Medicare Patients with a Pressure Ulcer Diagnosis: Coding Patterns and Impact on Hospital-Acquired Pressure Ulcer Rates.

    PubMed

    Squitieri, Lee; Waxman, Daniel A; Mangione, Carol M; Saliba, Debra; Ko, Clifford Y; Needleman, Jack; Ganz, David A

    2018-01-25

    To evaluate national present-on-admission (POA) reporting for hospital-acquired pressure ulcers (HAPUs) and examine the impact of quality measure exclusion criteria on HAPU rates. Medicare inpatient, outpatient, and nursing facility data as well as independent provider claims (2010-2011). Retrospective cross-sectional study. We evaluated acute inpatient hospital admissions among Medicare fee-for-service (FFS) beneficiaries in 2011. Admissions were categorized as follows: (1) no pressure ulcer diagnosis, (2) new pressure ulcer diagnosis, and (3) previously documented pressure ulcer diagnosis. HAPU rates were calculated by varying patient exclusion criteria. Among admissions with a pressure ulcer diagnosis, we observed a large discrepancy in the proportion of admissions with a HAPU based on hospital-reported POA data (5.2 percent) and the proportion with a new pressure ulcer diagnosis based on patient history in billing claims (49.7 percent). Applying quality measure exclusion criteria resulted in removal of 91.2 percent of admissions with a pressure injury diagnosis from HAPU rate calculations. As payers and health care organizations expand the use of quality measures, it is important to consider how the measures are implemented, coding revisions to improve measure validity, and the impact of patient exclusion criteria on provider performance evaluation. © Health Research and Educational Trust.

  1. X-33 LH2 Tank Failure Investigation Findings

    NASA Technical Reports Server (NTRS)

    Niedermeyer, Melinda; Munafo, Paul (Technical Monitor)

    2002-01-01

    This viewgraph presentation gives an overview of the X-33 LH2 tank failure investigation findings. The conclusions of the investigation include the following: (1) the inner skin microcracked and hydrogen infiltrated; (2) the cracks grew larger under pressure; (3) when pressure was removed, the cracks closed slightly; (4) when the tank was drained and warmed, the cracks closed and blocked the leak path; (5) FOD and debond areas provided an opportunity for a leak path; and (6) there is still hydrogen in the the other three lobes today.

  2. Soft x-ray spectroscopy of high pressure liquid.

    PubMed

    Qiao, Ruimin; Xia, Yujian; Feng, Xuefei; Macdougall, James; Pepper, John; Armitage, Kevin; Borsos, Jason; Knauss, Kevin G; Lee, Namhey; Allézy, Arnaud; Gilbert, Benjamin; MacDowell, Alastair A; Liu, Yi-Sheng; Glans, Per-Anders; Sun, Xuhui; Chao, Weilun; Guo, Jinghua

    2018-01-01

    We describe a new experimental technique that allows for soft x-ray spectroscopy studies (∼100-1000 eV) of high pressure liquid (∼100 bars). We achieve this through a liquid cell with a 100 nm-thick Si 3 N 4 membrane window, which is sandwiched by two identical O-rings for vacuum sealing. The thin Si 3 N 4 membrane allows soft x-rays to penetrate, while separating the high-pressure liquid under investigation from the vacuum required for soft x-ray transmission and detection. The burst pressure of the Si 3 N 4 membrane increases with decreasing size and more specifically is inversely proportional to the side length of the square window. It also increases proportionally with the membrane thickness. Pressures > 60 bars could be achieved for 100 nm-thick square Si 3 N 4 windows that are smaller than 65 μm. However, above a certain pressure, the failure of the Si wafer becomes the limiting factor. The failure pressure of the Si wafer is sensitive to the wafer thickness. Moreover, the deformation of the Si 3 N 4 membrane is quantified using vertical scanning interferometry. As an example of the performance of the high-pressure liquid cell optimized for total-fluorescence detected soft x-ray absorption spectroscopy (sXAS), the sXAS spectra at the Ca L edge (∼350 eV) of a CaCl 2 aqueous solution are collected under different pressures up to 41 bars.

  3. Soft x-ray spectroscopy of high pressure liquid

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Qiao, Ruimin; Xia, Yujian; Feng, Xuefei

    Here, we describe a new experimental technique that allows for soft x-ray spectroscopy studies (~100-1000 eV) of high pressure liquid (~100 bars). We achieve this through a liquid cell with a 100 nm-thick Si 3N 4 membrane window, which is sandwiched by two identical O-rings for vacuum sealing. The thin Si 3N 4 membrane allows soft x-rays to penetrate, while separating the high-pressure liquid under investigation from the vacuum required for soft x-ray transmission and detection. The burst pressure of the Si 3N 4 membrane increases with decreasing size and more specifically is inversely proportional to the side length ofmore » the square window. It also increases proportionally with the membrane thickness. Pressures > 60 bars could be achieved for 100 nm-thick square Si 3N 4 windows that are smaller than 65 μm. However, above a certain pressure, the failure of the Si wafer becomes the limiting factor. The failure pressure of the Si wafer is sensitive to the wafer thickness. Moreover, the deformation of the Si 3N 4 membrane is quantified using vertical scanning interferometry. As an example of the performance of the high-pressure liquid cell optimized for total-fluorescence detected soft x-ray absorption spectroscopy (sXAS), the sXAS spectra at the Ca L edge (~350 eV) of a CaCl 2 aqueous solution are collected under different pressures up to 41 bars.« less

  4. Soft x-ray spectroscopy of high pressure liquid

    DOE PAGES

    Qiao, Ruimin; Xia, Yujian; Feng, Xuefei; ...

    2018-01-01

    Here, we describe a new experimental technique that allows for soft x-ray spectroscopy studies (~100-1000 eV) of high pressure liquid (~100 bars). We achieve this through a liquid cell with a 100 nm-thick Si 3N 4 membrane window, which is sandwiched by two identical O-rings for vacuum sealing. The thin Si 3N 4 membrane allows soft x-rays to penetrate, while separating the high-pressure liquid under investigation from the vacuum required for soft x-ray transmission and detection. The burst pressure of the Si 3N 4 membrane increases with decreasing size and more specifically is inversely proportional to the side length ofmore » the square window. It also increases proportionally with the membrane thickness. Pressures > 60 bars could be achieved for 100 nm-thick square Si 3N 4 windows that are smaller than 65 μm. However, above a certain pressure, the failure of the Si wafer becomes the limiting factor. The failure pressure of the Si wafer is sensitive to the wafer thickness. Moreover, the deformation of the Si 3N 4 membrane is quantified using vertical scanning interferometry. As an example of the performance of the high-pressure liquid cell optimized for total-fluorescence detected soft x-ray absorption spectroscopy (sXAS), the sXAS spectra at the Ca L edge (~350 eV) of a CaCl 2 aqueous solution are collected under different pressures up to 41 bars.« less

  5. Evaluation of chronic kidney disease in chronic heart failure: From biomarkers to arterial renal resistances

    PubMed Central

    Iacoviello, Massimo; Leone, Marta; Antoncecchi, Valeria; Ciccone, Marco Matteo

    2015-01-01

    Chronic kidney disease and its worsening are recurring conditions in chronic heart failure (CHF) which are independently associated with poor patient outcome. The heart and kidney share many pathophysiological mechanisms which can determine dysfunction in each organ. Cardiorenal syndrome is the condition in which these two organs negatively affect each other, therefore an accurate evaluation of renal function in the clinical setting of CHF is essential. This review aims to revise the parameters currently used to evaluate renal dysfunction in CHF with particular reference to the usefulness and the limitations of biomarkers in evaluating glomerular dysfunction and tubular damage. Moreover, it is reported the possible utility of renal arterial resistance index (a parameter associated with abnormalities in renal vascular bed) for a better assesment of kidney disfunction. PMID:25610846

  6. Fluid removal in acute heart failure: diuretics versus devices.

    PubMed

    Krishnamoorthy, Arun; Felker, G Michael

    2014-10-01

    Fluid removal and relief of congestion are central to treatment of acute heart failure. Diuretics have been the decongestive mainstay but their known limitations have led to the exploration of alternative strategies. This review compares diuretics with ultrafiltration and examines the recent evidence evaluating their use. Relevant recent studies are the Diuretic Optimization Strategies Evaluation trial (of diuretics) and the Cardiorenal Rescue Study in Acute Decompensated Heart Failure (of ultrafiltration). The Diuretic Optimization Strategies Evaluation study evaluated strategies of loop diuretic use during acute heart failure (continuous infusion versus intermittent bolus and high dose versus low dose). After 72  h, there was no significant difference with either comparison for the coprimary end points. Patients treated with a high-dose strategy tended to have greater diuresis and more decongestion compared with low-dose therapy, at the cost of transient changes in renal function. The Cardiorenal Rescue Study in Acute Decompensated Heart Failure study showed that in acute heart failure patients with persistent congestion and worsening renal function, ultrafiltration, as compared with a medical therapy, was associated with similar weight loss but greater increase in serum creatinine and more adverse events. Decongestion remains a major challenge in acute heart failure. Although recent studies provide useful data to guide practice, the relatively poor outcomes point to the continued need to identify better strategies for safe and effective decongestion.

  7. Psychometric Evaluation of Two Appetite Questionnaires in Patients With Heart Failure.

    PubMed

    Andreae, Christina; Strömberg, Anna; Sawatzky, Richard; Årestedt, Kristofer

    2015-12-01

    Decreased appetite in heart failure (HF) may lead to undernutrition which could negatively influence prognosis. Appetite is a complex clinical issue that is often best measured with the use of self-report instruments. However, there is a lack of self-rated appetite instruments. The Council on Nutrition Appetite Questionnaire (CNAQ) and the Simplified Nutritional Appetite Questionnaire (SNAQ) are validated instruments developed primarily for elderly people. Yet, the psychometric properties have not been evaluated in HF populations. The aim of the present study was to evaluate the psychometric properties of CNAQ and SNAQ in patients with HF. A total of 186 outpatients with reduced ejection fraction and New York Heart Association (NYHA) functional classifications II-IV were included (median age 72 y; 70% men). Data were collected with the use of a questionnaire that included the CNAQ and SNAQ. The psychometric evaluation included data quality, factor structure, construct validity, known-group validity, and internal consistency. Unidimensionality was supported by means of parallel analysis and confirmatory factor analyses (CFAs). The CFA results indicated sufficient model fit. Both construct validity and known-group validity were supported. Internal consistency reliability was acceptable, with ordinal coefficient alpha estimates of 0.82 for CNAQ and 0.77 for SNAQ. CNAQ and SNAQ demonstrated sound psychometric properties and can be used to measure appetite in patients with HF. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. CESAR: conventional ventilatory support vs extracorporeal membrane oxygenation for severe adult respiratory failure.

    PubMed

    Peek, Giles J; Clemens, Felicity; Elbourne, Diana; Firmin, Richard; Hardy, Pollyanna; Hibbert, Clare; Killer, Hilliary; Mugford, Miranda; Thalanany, Mariamma; Tiruvoipati, Ravin; Truesdale, Ann; Wilson, Andrew

    2006-12-23

    An estimated 350 adults develop severe, but potentially reversible respiratory failure in the UK annually. Current management uses intermittent positive pressure ventilation, but barotrauma, volutrauma and oxygen toxicity can prevent lung recovery. An alternative treatment, extracorporeal membrane oxygenation, uses cardio-pulmonary bypass technology to temporarily provide gas exchange, allowing ventilator settings to be reduced. While extracorporeal membrane oxygenation is proven to result in improved outcome when compared to conventional ventilation in neonates with severe respiratory failure, there is currently no good evidence from randomised controlled trials to compare these managements for important clinical outcomes in adults, although evidence from case series is promising. The aim of the randomised controlled trial of Conventional ventilatory support vs extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR) is to assess whether, for patients with severe, but potentially reversible, respiratory failure, extracorporeal membrane oxygenation will increase the rate of survival without severe disability ('confined to bed' and 'unable to wash or dress') by six months post-randomisation, and be cost effective from the viewpoints of the NHS and society, compared to conventional ventilatory support. Following assent from a relative, adults (18-65 years) with severe, but potentially reversible, respiratory failure (Murray score >/= 3.0 or hypercapnea with pH < 7.2) will be randomised for consideration of extracorporeal membrane oxygenation at Glenfield Hospital, Leicester or continuing conventional care in a centre providing a high standard of conventional treatment. The central randomisation service will minimise by type of conventional treatment centre, age, duration of high pressure ventilation, hypoxia/hypercapnea, diagnosis and number of organs failed, to ensure balance in key prognostic variables. Extracorporeal membrane oxygenation

  9. International Space Station Powered Bolt Nut Anomaly and Failure Analysis Summary

    NASA Technical Reports Server (NTRS)

    Sievers, Daniel E.; Warden, Harry K.

    2010-01-01

    A key mechanism used in the on-orbit assembly of the International Space Station (ISS) pressurized elements is the Common Berthing Mechanism. The mechanism that effects the structural connection of the Common Berthing Mechanism halves is the Powered Bolt Assembly. There are sixteen Powered Bolt Assemblies per Common Berthing Mechanism. The Common Berthing Mechanism has a bolt which engages a self aligning Powered Bolt Nut (PBN) on the mating interface (Figure 1). The Powered Bolt Assemblies are preloaded to approximately 84.5 kN (19000 lb) prior to pressurization of the CBM. The PBNs mentioned below, manufactured in 2009, will be used on ISS future missions. An on orbit functional failure of this hardware would be unacceptable and in some instances catastrophic due to the failure of modules to mate and seal the atmosphere, risking loss of crew and ISS functions. The manufacturing processes that create the PBNs need to be strictly controlled. Functional (torque vs. tension) acceptance test failures will be the result of processes not being strictly followed. Without the proper knowledge of thread tolerances, fabrication techniques, and dry film lubricant application processes, PBNs will be, and have been manufactured improperly. The knowledge gained from acceptance test failures and the resolution of those failures, thread fabrication techniques and thread dry film lubrication processes can be applied to many aerospace mechanisms to enhance their performance. Test data and manufactured PBN thread geometry will be discussed for both failed and successfully accepted PBNs.

  10. International Space Station Powered Bolt Nut Anomaly and Failure Analysis Summary

    NASA Technical Reports Server (NTRS)

    Sievers, Daniel E.; Warden, Harry K.

    2010-01-01

    A key mechanism used in the on-orbit assembly of the International Space Station (ISS) pressurized elements is the Common Berthing Mechanism (CBM). The mechanism that effects the structural connection of the CBM halves is the Powered Bolt Assembly. There are sixteen Powered Bolt Assemblies per CBM. The CBM has a bolt which engages a self aligning Powered Bolt Nut (PBN) on the mating interface; see Figure 1. The Powered Bolt Assemblies are preloaded to approximately 19 kilo pounds (KIPs) prior to pressurization of the CBM. The PBNs mentioned below, manufactured in 2009, will be used on ISS future missions. An on orbit functional failure of this hardware would be unacceptable and in some instances catastrophic due to the failure of modules to mate and seal the atmosphere, risking loss of crew and ISS functions. The manufacturing processes which create the PBNs need to be strictly controlled. Functional (torque vs. tension) acceptance test failures will be the result of processes not being strictly followed. Without the proper knowledge of thread tolerances, fabrication techniques, and dry film lubricant application processes, PBNs will be, and have been manufactured improperly. The knowledge gained from acceptance test failures and the resolution of those failures, thread fabrication techniques and thread dry film lubrication processes can be applied to many aerospace mechanisms to enhance their performance. Test data and manufactured PBN thread geometry will be discussed for both failed and successfully accepted PBNs.

  11. [Effect of oxygen tubing connection site on percutaneous oxygen partial pressure and percutaneous carbon dioxide partial pressure in patients with chronic obstructive pulmonary disease during noninvasive positive pressure ventilation].

    PubMed

    Mi, S; Zhang, L M

    2017-04-12

    Objective: We evaluated the effects of administering oxygen through nasal catheters inside the mask or through the mask on percutaneous oxygen partial pressure (PcO(2))and percutaneous carbon dioxide partial pressure (PcCO(2)) during noninvasive positive pressure ventilation (NPPV) to find a better way of administering oxygen, which could increase PcO(2) by increasing the inspired oxygen concentration. Methods: Ten healthy volunteers and 9 patients with chronic obstructive pulmonary disease complicated by type Ⅱ respiratory failure were included in this study. Oxygen was administered through a nasal catheter inside the mask or through the mask (oxygen flow was 3 and 5 L/min) during NPPV. PcO(2) and PcCO(2) were measured to evaluate the effects of administering oxygen through a nasal catheter inside the mask or through the mask, indirectly reflecting the effects of administering oxygen through nasal catheter inside the mask or through the mask on inspired oxygen concentration. Results: Compared to administering oxygen through the mask during NPPV, elevated PcO(2) was measured in administering oxygen through the nasal catheter inside the mask, and the differences were statistically significant ( P <0.05). At the same time, there was no significant change in PcCO(2) ( P >0.05). Conclusion: Administering oxygen through a nasal catheter inside the mask during NPPV increased PcO(2) by increasing the inspired oxygen concentration but did not increase PcCO(2). This method of administering oxygen could conserve oxygen and be suitable for family NPPV. Our results also provided theoretical basis for the development of new masks.

  12. Kinin B1 receptor blockade and ACE inhibition attenuate cardiac postinfarction remodeling and heart failure in rats

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lin, Xinchun

    Introduction: The aim of the present study was to evaluate the effects of the novel kinin B1 receptor antagonist BI113823 on postinfarction cardiac remodeling and heart failure, and to determine whether B1 receptor blockade alters the cardiovascular effects of an angiotensin 1 converting enzyme (ACE) inhibitor in rats. Methods and results: Sprague Dawley rats were subjected to permanent occlusion of the left coronary artery. Cardiovascular function was determined at 6 weeks postinfarction. Treatment with either B1 receptor antagonist (BI113823) or an ACE inhibitor (lisinopril) alone or in combination significantly reduced the heart weight-to-body weight and lung weight-to-body weight ratios, andmore » improved postinfarction cardiac function as evidenced by greater cardiac output, the maximum rate of left ventricular pressure rise (± dP/dtmax), left ventricle ejection fraction, fractional shorting, better wall motion, and attenuation of elevated left ventricular end diastolic pressure (LVEDP). Furthermore, all three treatment groups exhibited significant reduction in cardiac interstitial fibrosis, collagen deposition, CD68 positive macrophages, neutrophils, and proinflammatory cytokine production (TNF-α and IL-1β), compared to vehicle controls. Conclusion: The present study shows that treatment with the novel kinin B1 receptor antagonist, BI113823, reduces postinfarction cardiac remodeling and heart failure, and does not influence the cardiovascular effects of the ACE inhibitor. - Highlights: • We examined the role of kinin B1 receptors in the development of heart failure. • Kinin B1 receptor blockade attenuates post-infarction cardiac remodeling. • Kinin B1 receptor blockade improves dysfunction, and prevented heart failure. • B1 receptor blockade does not affect the cardio-protection of an ACE inhibitor.« less

  13. Evaluation of Pressure Generated by Resistors From Different Positive Expiratory Pressure Devices.

    PubMed

    Fagevik Olsén, Monika; Carlsson, Maria; Olsén, Erik; Westerdahl, Elisabeth

    2015-10-01

    Breathing exercises with positive expiratory pressure (PEP) are used to improve pulmonary function and airway clearance. Different PEP devices are available, but there have been no studies that describe the pressure generated by different resistors. The purpose of this study was to compare pressures generated from the proprietary resistor components of 4 commercial flow-dependent PEP valves with all other parameters kept constant. Resistors from 4 flow-regulated PEP devices (Pep/Rmt system, Wellspect HealthCare; Pipe P breathing exerciser, Koo Medical Equipment; Mini-PEP, Philips Respironics [including resistors by Rüsch]; and 15-mm endo-adapter, VBM Medizintechnik) were tested randomly by a blinded tester at constant flows of 10 and 18 L/min from an external gas system. All resistors were tested 3 times. Resistors with a similar diameter produced statistically significant different pressures at the same flow. The differences were smaller when the flow was 10 L/min compared with 18 L/min. The differences were also smaller when the diameter of the resistor was increased. The pressures produced by the 4 resistors of the same size were all significantly different when measuring 1.5- and 2.0-mm resistors at a flow of 10 L/min and 2.0-mm resistors at a flow of 18 L/min (P < .001). There were no significant differences between any of the resistors when testing sizes of 4.5 and 5.0 mm at either flow. The Mini-PEP and adapter resistors gave the highest pressures. Pressures generated by the different proprietary resistor components of 4 commercial PEP devices were not comparable, even though the diameter of the resistors is reported to be the same. The pressures generated were significantly different, particularly when using small-diameter resistors at a high flow. Therefore, the resistors may not be interchangeable. This is important information for clinicians, particularly when considering PEP for patients who do not tolerate higher pressures. Copyright © 2015 by

  14. Crucial role of rho-kinase in pressure overload-induced right ventricular hypertrophy and dysfunction in mice.

    PubMed

    Ikeda, Shohei; Satoh, Kimio; Kikuchi, Nobuhiro; Miyata, Satoshi; Suzuki, Kota; Omura, Junichi; Shimizu, Toru; Kobayashi, Kenta; Kobayashi, Kazuto; Fukumoto, Yoshihiro; Sakata, Yasuhiko; Shimokawa, Hiroaki

    2014-06-01

    Right ventricular (RV) failure is the leading cause of death in various cardiopulmonary diseases, including pulmonary hypertension. It is generally considered that the RV is vulnerable to pressure overload as compared with the left ventricle (LV). However, as compared with LV failure, the molecular mechanisms of RV failure are poorly understood, and hence therapeutic targets of the disorder remain to be elucidated. Thus, we aimed to identify molecular therapeutic targets for RV failure in a mouse model of pressure overload. To induce pressure overload to respective ventricles, we performed pulmonary artery constriction or transverse aortic constriction in mice. We first performed microarray analysis and found that the molecules related to RhoA/Rho-kinase and integrin pathways were significantly upregulated in the RV with pulmonary artery constriction compared with the LV with transverse aortic constriction. Then, we examined the responses of both ventricles to chronic pressure overload in vivo. We demonstrated that compared with transverse aortic constriction, pulmonary artery constriction caused greater extents of mortality, Rho-kinase expression (especially ROCK2 isoform), and oxidative stress in pressure-overloaded RV, reflecting the weakness of the RV in response to pressure overload. Furthermore, mice with myocardial-specific overexpression of dominant-negative Rho-kinase showed resistance to pressure overload-induced hypertrophy and dysfunction associated with reduced oxidative stress. Finally, dominant-negative Rho-kinase mice showed a significantly improved long-term survival in both pulmonary artery constriction and transverse aortic constriction as compared with littermate controls. These results indicate that the Rho-kinase pathway plays a crucial role in RV hypertrophy and dysfunction, suggesting that the pathway is a novel therapeutic target of RV failure in humans. © 2014 American Heart Association, Inc.

  15. Optimizing the effectiveness of a mechanical suture-based anulus fibrosus repair construct in an acute failure laboratory simulation.

    PubMed

    Bartlett, Ashley; Wales, Larry; Houfburg, Rodney; Durfee, William K; Griffith, Steven L; Bentley, Ishmael

    2013-10-01

    In vitro comparative, laboratory experiments. This study developed a laboratory apparatus that measured resistance to failure using pressures similar to intradiscal pressure of a lumbar spinal disk. Various combinations of an anular repair device were compared. Herniated material of the intervertebral disk is removed during a lumbar discectomy; however, the defect in the anulus fibrosus remains and can provide a pathway for future herniation. Repairing the anulus fibrosus could mitigate this reherniation and improve patient outcomes. A pneumatic cylinder was used to increase the pressure of a sealed chamber until artificial nucleus pulposus material was expulsed through either a 3-mm circular (diameter) or a 6-mm slit anular defect created in a surrogate anulus fibrosus. Each unrepaired condition was compared with 3 repaired conditions using a commercially available soft tissue repair system. The repaired conditions included: (1) a single tension band; (2) 2 tension bands in a cruciate pattern; or (3) 2 tension bands in a parallel pattern. Maximum pressure at the point of extrusion of the internal chamber material and failure or nonfailure of the repair was measured. Significant differences were detected (P<0.05) in maximum failure pressures for the nonrepaired (control) versus repaired conditions. With 1 or 2 tension bands repairing the circular defect, the maximum failure pressure increased by approximately 76% and 131%, respectively. In addition, the failure pressure for 2 tension bands in either a cruciate or parallel configuration was not different, and was approximately 32% higher (P<0.05) than a single tension band in the case of the circular defect. Similar results were seen for the slit defect, with the exception that no difference between the repaired conditions (ie, single vs. 2 tension bands) was detected. This laboratory simulation demonstrated that repairing the anulus fibrosus after a discectomy procedure can be beneficial for retaining intradiscal

  16. Automatic Monitoring System Design and Failure Probability Analysis for River Dikes on Steep Channel

    NASA Astrophysics Data System (ADS)

    Chang, Yin-Lung; Lin, Yi-Jun; Tung, Yeou-Koung

    2017-04-01

    The purposes of this study includes: (1) design an automatic monitoring system for river dike; and (2) develop a framework which enables the determination of dike failure probabilities for various failure modes during a rainstorm. The historical dike failure data collected in this study indicate that most dikes in Taiwan collapsed under the 20-years return period discharge, which means the probability of dike failure is much higher than that of overtopping. We installed the dike monitoring system on the Chiu-She Dike which located on the middle stream of Dajia River, Taiwan. The system includes: (1) vertical distributed pore water pressure sensors in front of and behind the dike; (2) Time Domain Reflectometry (TDR) to measure the displacement of dike; (3) wireless floating device to measure the scouring depth at the toe of dike; and (4) water level gauge. The monitoring system recorded the variation of pore pressure inside the Chiu-She Dike and the scouring depth during Typhoon Megi. The recorded data showed that the highest groundwater level insides the dike occurred 15 hours after the peak discharge. We developed a framework which accounts for the uncertainties from return period discharge, Manning's n, scouring depth, soil cohesion, and friction angle and enables the determination of dike failure probabilities for various failure modes such as overtopping, surface erosion, mass failure, toe sliding and overturning. The framework was applied to Chiu-She, Feng-Chou, and Ke-Chuang Dikes on Dajia River. The results indicate that the toe sliding or overturning has the highest probability than other failure modes. Furthermore, the overall failure probability (integrate different failure modes) reaches 50% under 10-years return period flood which agrees with the historical failure data for the study reaches.

  17. On high-pressure melting of tantalum

    NASA Astrophysics Data System (ADS)

    Luo, Sheng-Nian; Swift, Damian C.

    2007-01-01

    The issues related to high-pressure melting of Ta are discussed within the context of diamond-anvil cell (DAC) and shock wave experiments, theoretical calculations and common melting models. The discrepancies between the extrapolations of the DAC melting curve and the melting point inferred from shock wave experiments, cannot be reconciled either by superheating or solid-solid phase transition. The failure to reproduce low-pressure DAC melting curve by melting models such as dislocation-mediated melting and the Lindemann law, and molecular dynamics and quantum mechanics-based calculations, undermines their predictions at moderate and high pressures. Despite claims to the contrary, the melting curve of Ta (as well as Mo and W) remains inconclusive at high pressures.

  18. The serine/threonine-protein kinase/endoribonuclease IRE1α protects the heart against pressure overload-induced heart failure.

    PubMed

    Steiger, DeAnna; Yokota, Tomohiro; Li, Jin; Ren, Shuxun; Minamisawa, Susumu; Wang, Yibin

    2018-05-16

    Heart failure is associated with induction of endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). The serine/threonine protein kinase/endoribonuclease IRE1α is a key protein in ER stress signal transduction. IRE1α activity can induce both protective UPR and apoptotic downstream signaling events, but the specific role for IRE1α activity in the heart is unknown. A major aim of this study was to characterize the specific contribution of IRE1α in cardiac physiology and pathogenesis. We used both cultured myocytes and a transgenic mouse line with inducible and cardiomyocyte-specific IRE1α overexpression as experimental models to achieve targeted IRE1α activation. IRE1α expression induced a potent but transient ER stress response in cardiomyocytes and did not cause significant effects in the intact heart under normal physiological condition. Furthermore, the IRE1α-activated transgenic heart responding to pressure overload exhibited preserved function and reduced fibrotic area, associated with increased adaptive UPR signaling and with blunted inflammatory and pathological gene expression. Therefore, we conclude that IRE1α induces transient ER stress signaling and confers a protective effect against pressure overload-induced pathological remodeling in the heart. To our knowledge, this report provides first direct evidence of a specific and protective role for IRE1α in the heart and reveals an interaction between ER stress signaling and inflammatory regulation in the pathologically stressed heart. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Use of prazosin in management of hypertension in patients with chronic renal failure and in renal transplant recipients.

    PubMed Central

    Curtis, J R; Bateman, F J

    1975-01-01

    Prazosin was used in combination with other antihypertensive drugs in the successful management of hypertension in seven patients with chronic renal failure and six renal transplant recipients, also with chronic renal failure. The addition of small doses of prazosin (mean 3 mg/day) to the antihypertensive regimen produced significant falls in systolic and diastolic blood pressures in both the lying and standing positions. The standing blood pressures were significantly lower than the lying blood pressures during prazosin treatment. Neither the mean blood urea concentrations nor the mean plasma creatinine concentrations changed significantly during prazosin administration. Chromium-51 edetic acid clearances did not change significantly during prazosin treatment in the seven patients in whom it was measured. Severe symptomatic postural hypotension occurred in one patient a week after starting prazosin 3 mg/day. This hypotensive episode was associated with a transient and reversible deterioration in renal function. Another patient developed a rash while on prazosin but it was probably related to propranolol rather than prazosin. Prazosin is thus an effective antihypertensive drug in patients with chronic renal failure, and it may be used with a variety of other drugs. It should be used cautiously, however, since patients with chronic renal failure may respond to small doses, and significant postural falls in blood pressure may result. There was no evidence that the use of prazosin resulted in progressive deterioration in the residual renal function of the patients with chronic renal failure. PMID:811312

  20. Use of prazosin in management of hypertension in patients with chronic renal failure and in renal transplant recipients.

    PubMed

    Curtis, J R; Bateman, F J

    1975-11-22

    Prazosin was used in combination with other antihypertensive drugs in the successful management of hypertension in seven patients with chronic renal failure and six renal transplant recipients, also with chronic renal failure. The addition of small doses of prazosin (mean 3 mg/day) to the antihypertensive regimen produced significant falls in systolic and diastolic blood pressures in both the lying and standing positions. The standing blood pressures were significantly lower than the lying blood pressures during prazosin treatment. Neither the mean blood urea concentrations nor the mean plasma creatinine concentrations changed significantly during prazosin administration. Chromium-51 edetic acid clearances did not change significantly during prazosin treatment in the seven patients in whom it was measured. Severe symptomatic postural hypotension occurred in one patient a week after starting prazosin 3 mg/day. This hypotensive episode was associated with a transient and reversible deterioration in renal function. Another patient developed a rash while on prazosin but it was probably related to propranolol rather than prazosin. Prazosin is thus an effective antihypertensive drug in patients with chronic renal failure, and it may be used with a variety of other drugs. It should be used cautiously, however, since patients with chronic renal failure may respond to small doses, and significant postural falls in blood pressure may result. There was no evidence that the use of prazosin resulted in progressive deterioration in the residual renal function of the patients with chronic renal failure.