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1

Understanding cardiac output  

PubMed Central

Cardiac output is the amount of blood the heart pumps in 1 minute, and it is dependent on the heart rate, contractility, preload, and afterload. Understanding of the applicability and practical relevance of each of these four components is important when interpreting cardiac output values. In the present article, we use a simple analogy comparing cardiac output with the speed of a bicycle to help appreciate better the effects of various disease processes and interventions on cardiac output and its four components.

Vincent, Jean-Louis

2008-01-01

2

Crystalloid and colloid preload for maintaining cardiac output in elderly patients undergoing total hip replacement under spinal anesthesia  

PubMed Central

The aim of the present study was to compare the effects of colloid and crystalloid preload on cardiac output (CO) and incidence of hypotension in elderly patients under spinal anesthesia (SA). A randomized, double-blinded study was conducted including 47 elderly patients undergoing scheduled total hip replacement (THR), who were randomized to three groups: the control group (C group, n = 15), crystalloid (RS group, n =16) and colloid group (HES group, n = 16). An intravenous preload of 8 mL/kg of either lactated Ringer's solution in the RS group or 6% hydroxyethyl starch in the HES group was infused within 20 min before SA induction, while no intravenous preload was given in the C group. There was a trend of decrease in CO and systolic blood pressure after SA with time in the C group. In the RS and HES groups, CO increased significantly after fluid preloading as compared with baseline (P < 0.01). Thereafter, CO remained higher than baseline until 30 min after SA in the HES group. The change of systolic blood pressure was similar to CO, but no significant difference from baseline was observed in each group. Hypotension occurred in 3 patients in the C group and one each in the RS and HES group, respectively (P = 0.362). Intravascular volume preload with colloid is more effective than crystalloid solution in maintaining CO, which may be improved the hemodynamic stability in elderly patients during SA.

Xie, Rufeng; Wang, Lizhong; Bao, Hongguang

2011-01-01

3

Predictors of low cardiac output syndrome after coronary artery bypass  

Microsoft Academic Search

The purpose of this study was to identify patients at risk for the development of low cardiac output syndrome after coronary artery bypass. Low cardiac output syndrome was defined as the need for postoperative intraaortic balloon pump or inotropic support for longer than 30 minutes in the intensive care unit to maintain the systolic blood pressure greater than 90 mm

Vivek Rao; Joan Ivanov; Richard D. Weisel; John S. Ikonomidis; George T. Christakis; Tirone E. David

1996-01-01

4

Clinical review: Positive end-expiratory pressure and cardiac output  

Microsoft Academic Search

In patients with acute lung injury, high levels of positive end-expiratory pressure (PEEP) may be necessary to maintain or restore oxygenation, despite the fact that 'aggressive' mechanical ventilation can markedly affect cardiac function in a complex and often unpredictable fashion. As heart rate usually does not change with PEEP, the entire fall in cardiac output is a consequence of a

Thomas Luecke; Paolo Pelosi

2005-01-01

5

Cardiac output: a view from Buffalo  

Microsoft Academic Search

Cardiac output ( Q?) is a primary determinant of blood pressure and O 2 delivery and is critical in the maintenance of homeostasis, particularly during environmental stress. Cardiac output can be determined invasively in patients; however, indirect methods are required for other situations. Soluble gas techniques are widely used to determine Q?. Historically, measurements during a breathhold, prolonged expiration and

A. J. Olszowka; B. E. Shykoff; D. R. Pendergast; C. E. G. Lundgren; L. E. Farhi

2003-01-01

6

Near continuous cardiac output by thermodilution.  

PubMed

A new thermodilution method for frequent (near continuous) estimation of cardiac output, without manual injection of fluid into the blood, was tested. The method utilizes a pulmonary artery catheter equipped with a fluid filled heat exchanger. The technique is based on cyclic cooling of the blood in the right atrium and measurement of the temperature changes in the pulmonary artery. Using this technique, a new estimate of cardiac output can be obtained every 32 s. Cardiac output estimates, obtained for a running mean of three measurements with this method, were compared to the mean of three conventional thermodilution measurements. The measurements were obtained during short periods of stable respiration and circulation. In six pigs, we made 46 paired measurements of conventional thermodilution (TD) and near continuous (TDc) thermodilution. The cardiac output (COTD) ranged from 2.4-13.7 l/min (mean 5.4 l/min). The best linear fit through the paired data points was COTDc = -0.57 + 1.01 COTD. The mean difference between the methods was -0.50 l/min (S.D. = 0.39). The mean coefficient of variation of repeated measurements with the near continuous thermodilution was 3.6%. Considering changes of more than 0.25 l/min to be significant, all changes in cardiac output measured by conventional thermodilution were followed by the running mean of three near continuous thermodilution estimates. This study demonstrates the feasibility of the new method to monitor cardiac output, and to detect all changes greater than 0.25 l/min. PMID:9269617

Jansen, J R; Johnson, R W; Yan, J Y; Verdouw, P D

1997-07-01

7

Noninvasive Cardiac Output Assessment During Heart Surgery  

Microsoft Academic Search

Objective. To evaluate the reliability of a new noninvasivemethod for the assessment of cardiac output with the partial carbondioxide rebreathing technique. Methods. This technique wasapplied to patients undergoing heart surgery. Values of cardiac indexobtained with this equipment were compared with the artero-venousCO2 gradient, a reliable index of cardiovascular status.Positive and negative predictive values of the test were assessed.Results. A total

Piero Ceriana; Marco Maurelli; Antonio Braschi; Paola Baiardi; Donatella De Amici

2002-01-01

8

Determination of cardiac output by Doppler echocardiography  

Microsoft Academic Search

Cardiac output determined by Doppler echocardiography was compared with that determined by thermodilution at rest and during dobutamine infusion in 10 patients (group A) and by the Fick method at rest in 11 patients (group B). All patients had angina pectoris without valvular heart disease. Maximum spatial blood velocity and cross sectional aortic area were estimated by the Doppler technique

H Ihlen; J P Amlie; J Dale; K Forfang; S Nitter-Hauge; J E Otterstad; S Simonsen; E Myhre

1984-01-01

9

Clinical review: Positive end-expiratory pressure and cardiac output  

PubMed Central

In patients with acute lung injury, high levels of positive end-expiratory pressure (PEEP) may be necessary to maintain or restore oxygenation, despite the fact that 'aggressive' mechanical ventilation can markedly affect cardiac function in a complex and often unpredictable fashion. As heart rate usually does not change with PEEP, the entire fall in cardiac output is a consequence of a reduction in left ventricular stroke volume (SV). PEEP-induced changes in cardiac output are analyzed, therefore, in terms of changes in SV and its determinants (preload, afterload, contractility and ventricular compliance). Mechanical ventilation with PEEP, like any other active or passive ventilatory maneuver, primarily affects cardiac function by changing lung volume and intrathoracic pressure. In order to describe the direct cardiocirculatory consequences of respiratory failure necessitating mechanical ventilation and PEEP, this review will focus on the effects of changes in lung volume, factors controlling venous return, the diastolic interactions between the ventricles and the effects of intrathoracic pressure on cardiac function, specifically left ventricular function. Finally, the hemodynamic consequences of PEEP in patients with heart failure, chronic obstructive pulmonary disease and acute respiratory distress syndrome are discussed.

Luecke, Thomas; Pelosi, Paolo

2005-01-01

10

Pulseco: a less-invasive method to monitor cardiac output from arterial pressure after cardiac surgery  

Microsoft Academic Search

BackgroundCardiac output is often monitored after cardiac operations with a pulmonary artery catheter. A new method has been introduced that measures cardiac output by lithium dilution (LiDCO) and uses these data to calibrate a system (PulseCO) that calculates cardiac output continuously from the energy of the arterial pressure waveform. It is unknown whether PulseCO measurements are valid early after cardiac

Timothy T Hamilton; Lynne M Huber; Michael E Jessen

2002-01-01

11

Reduced maximal cardiac output at altitude — mechanisms and significance  

Microsoft Academic Search

When a lowlander ascends to altitude and acclimatizes over days to weeks, both maximal exercise capacity and maximal cardiac output are reduced compared to sea level. Of the several possible mechanisms underlying this reduction of maximal cardiac output, the available data are interpreted as supporting the simplest hypothesis — that this merely reflects the reduced requirement for muscle blood flow

Peter D Wagner

2000-01-01

12

Modelflow underestimates cardiac output in heat-stressed individuals  

PubMed Central

An estimation of cardiac output can be obtained from arterial pressure waveforms using the Modelflow method. However, whether the assumptions associated with Modelflow calculations are accurate during whole body heating is unknown. This project tested the hypothesis that cardiac output obtained via Modelflow accurately tracks thermodilution-derived cardiac outputs during whole body heat stress. Acute changes of cardiac output were accomplished via lower-body negative pressure (LBNP) during normothermic and heat-stressed conditions. In nine healthy normotensive subjects, arterial pressure was measured via brachial artery cannulation and the volume-clamp method of the Finometer. Cardiac output was estimated from both pressure waveforms using the Modeflow method. In normothermic conditions, cardiac outputs estimated via Modelflow (arterial cannulation: 6.1 ± 1.0 l/min; Finometer 6.3 ± 1.3 l/min) were similar with cardiac outputs measured by thermodilution (6.4 ± 0.8 l/min). The subsequent reduction in cardiac output during LBNP was also similar among these methods. Whole body heat stress elevated internal temperature from 36.6 ± 0.3 to 37.8 ± 0.4°C and increased cardiac output from 6.4 ± 0.8 to 10.9 ± 2.0 l/min when evaluated with thermodilution (P < 0.001). However, the increase in cardiac output estimated from the Modelflow method for both arterial cannulation (2.3 ± 1.1 l/min) and Finometer (1.5 ± 1.2 l/min) was attenuated compared with thermodilution (4.5 ± 1.4 l/min, both P < 0.01). Finally, the reduction in cardiac output during LBNP while heat stressed was significantly attenuated for both Modelflow methods (cannulation: ?1.8 ± 1.2 l/min, Finometer: ?1.5 ± 0.9 l/min) compared with thermodilution (?3.8 ± 1.19 l/min). These results demonstrate that the Modelflow method, regardless of Finometer or direct arterial waveforms, underestimates cardiac output during heat stress and during subsequent reductions in cardiac output via LBNP.

Shibasaki, Manabu; Wilson, Thad E.; Bundgaard-Nielsen, Morten; Seifert, Thomas; Secher, Niels H.

2011-01-01

13

The relationship between cardiac output and effective renal plasma flow in patients with cardiac disease  

Microsoft Academic Search

The relationship between effective renal plasma flow (ERPF) and cardiac output was examined in 46 patients (22 with congestive heart failure and 24 following cardiac surgical procedures) by simultaneously measuring the global ERPF by the single-injection method and cardiac output by the thermodilution method. Of the patients in the heart-failure group, 21 also had pulmonary artery end diastolic pressure (PAEDP)

David McGiffin; W. Newlon Tauxe; Clifton Lewis; Robert Karp; John Mantle

1984-01-01

14

Evaluation of Noninvasive Cardiac Output Methods During Exercise.  

National Technical Information Service (NTIS)

Noninvasive techniques to estimate cardiac output (Qc) will be used during future space flight. This retrospective literature survey compared the Qc techniques of carbon dioxide rebreathing (CO2-R), CO2 single breath (CO2-S), Doppler (DOP), impedance (IM)...

A. D. Moore L. H. Barrows M. Rashid S. F. Siconolfi

1992-01-01

15

High-Output Cardiac Failure Revealing Primary Plasma Cell Leukemia  

PubMed Central

High-output cardiac failure in multiple myeloma (MM) is related to arteriovenous shunting in bone infiltrate disease. We describe such a complication in a patient with primary plasma cell leukemia (pPCL) without bone disease. We review the mechanisms that could be involved. As previously described, traditional cardiac failure therapy is not effective. pPCL therapy should not be delayed.

Chaoui, Driss; Gallet, Bruno; Genet, Philippe; Mbungani, Babette; Al Jijakli, Ahmad; Arakelyan, Nina; Mesbah, Louisa; Sutton, Laurent

2013-01-01

16

Evaluation of heavy water for indicator dilution cardiac output measurement  

SciTech Connect

We evaluated deuterium oxide (D2O) as a tracer for cardiac output measurements. Cardiac output measurements made by thermodilution were compared with those made by indicator dilution with D2O and indocyanine green as tracers. Five triplicate measurements for each method were made at intervals of 30 minutes in each of 9 anesthetized, mechanically ventilated goats. Cardiac output ranged between 0.68 and 3.79 L/min. The 45 data points yielded a correlation coefficient of 0.948 for the comparison of D2O indicator dilution cardiac output measurements with thermodilution measurements and a linear regression slope of 1.046. D2O indicator dilution measurements were biased by -0.11 +/- 0.22 L/min compared with thermodilution measurements and had a standard deviation of +/- 0.12 L/min for triplicate measurements. Hematocrits ranging between 20 and 50 vol% had no effect on optical density for D2O. D2O is more stable than indocyanine green and approximately one-tenth the price (40 cents per injection compared with $4). The basic instrumentation cost of approximately $9,000 is an additional initial expense, but provides the ability to perform pulmonary extravascular water measurements with a double-indicator dilution technique. D2O has potential as a tracer for the clinical determination of indicator dilution cardiac output measurements and pulmonary extravascular water measurements.

Schreiner, M.S.; Leksell, L.G.; Neufeld, G.R. (Univ. of Pennsylvania School of Medicine, Philadelphia (USA))

1989-10-01

17

Minimally Invasive Monitoring of Cardiac Output in the Cardiac Surgery Intensive Care Unit  

Microsoft Academic Search

Cardiac output monitoring in the cardiac surgery patient is standard practice that is traditionally performed using the pulmonary\\u000a artery catheter. However, over the past 20 years, the value of pulmonary artery catheters has been challenged, with some authors\\u000a suggesting that its use might be not only unnecessary but also harmful. New minimally invasive devices that measure cardiac\\u000a output have become available.

Jamal A. Alhashemi; Maurizio Cecconi; Giorgio della Rocca; Maxime Cannesson; Christoph K. Hofer

2010-01-01

18

Validation of a continuous, arterial pressure-based cardiac output measurement: a multicenter, prospective clinical trial  

Microsoft Academic Search

INTRODUCTION: The present study compared measurements of cardiac output by an arterial pressure-based cardiac output (APCO) analysis method with measurement by intermittent thermodilution cardiac output (ICO) via pulmonary artery catheter in a clinical setting. METHODS: The multicenter, prospective clinical investigation enrolled patients with a clinical indication for cardiac output monitoring requiring pulmonary artery and radial artery catheters at two hospitals

William T McGee; Jeffrey L Horswell; Joachim Calderon; Gerard Janvier; Tom Van Severen; Greet Van den Berghe; Lori Kozikowski

2007-01-01

19

Effect of an irregular ventricular rhythm on cardiac output  

Microsoft Academic Search

The results of this study suggest that a third mechanism for the reduction of cardiac output in patients with AF is irregularity of the ventricular rhythm. Catheter ablation of the AV junction and implantation of a rate-responsive pacemaker in patients with AF may offer hemodynamic benefit beyond rate control by eliminating the irregularity that is present with medical therapy or

Emile G. Daoud; Raul Weiss; Marwan Bahu; Bradley P. Knight; Frank Bogun; Rajiva Goyal; Mark Harvey; S. Adam Strickberger; K. Ching Man; Fred Morady

1996-01-01

20

Noninvasive cardiac output estimation using a novel photoplethysmogram index  

Microsoft Academic Search

Cardiac output (CO) monitoring is essential for indicating the perfusion status of the human cardiovascular system under different physiological conditions. However, it is currently limited to hospital use due to the need for either skilled operators or big, expensive measurement devices. Therefore, in this paper we devise a new CO indicator which can easily be incorporated into existing wearable devices.

L. Wang; Emma Pickwell-MacPherson; Y. P. Liang; Y. T. Zhang

2009-01-01

21

Comparison of thermodilution bolus cardiac output and Doppler cardiac output in the early post-cardiopulmonary bypass period  

Microsoft Academic Search

Objective: To evaluate the accuracy of measuring cardiac output (CO) in the early post-cardiopulmonary bypass (CPB) period by comparing thermodilution with Doppler methods. Design: Prospective and blinded human trial. Setting: Academic medical center. Participants: Thirty adult patients undergoing elective coronary artery bypass graft surgery. Measurements and Main Results: Thermodilution CO (TCO) was obtained in triplicate. Doppler CO (DCO) in triplicate

Xiaoqin Zhao; John S. Mashikian; Pete Panzica; Adam Lerner; Kyung W. Park; Mark E. Comunale

2003-01-01

22

Continuous cardiac output measurement: pulse contour analysis vs thermodilution technique in cardiac surgical patients  

Microsoft Academic Search

We have analysed the clinical agreement between two methods of continuous cardiac output measurement: pulse contour analysis (PCCO) and a continuous thermodilution technique (CCO), were both compared with the intermittent bolus thermodilution technique (BCO). Measurements were performed in 26 cardiac surgical patients (groups 1 and 2, 13 patients each, with an ejection fraction .45% and ,45%, respectively) at 12 selected

G. Rodig; C. Prasser; C. Keyl; A. Liebold; J. Hobbhahn

1999-01-01

23

Cardiac output and sympathetic vasoconstrictor responses during upright tilt to presyncope in healthy humans  

PubMed Central

Syncope is a common clinical condition occurring even in healthy people without manifest cardiovascular disease. The purpose of this study was to determine the role of cardiac output and sympathetic vasoconstriction in neurally mediated (pre)syncope. Twenty-five subjects (age 15–51) with no history of recurrent syncope but who had presyncope during 60 deg upright tilt were studied; 10 matched controls who completed 45 min tilting were analysed retrospectively. Beat-to-beat haemodynamics (Modelflow), muscle sympathetic nerve activity (MSNA) and sympathetic baroreflex sensitivity (MSNA–diastolic pressure relation) were measured. MSNA, haemodynamic responses and baroreflex sensitivity during early tilting were not different between presyncopal subjects and controls. Hypotension was mediated by a drop in cardiac output in all presyncopal subjects, accompanied by a decrease in total peripheral resistance in 16 of them (64%, group A). In the other 9 subjects, total peripheral resistance was well maintained even at presyncope (36%, group B). Cardiac output was smaller (3.26 ± 0.34 (SEM) vs. 5.02 ± 0.40 l min?1, P= 0.01), while total peripheral resistance was greater (1327 ± 117 vs. 903 ± 80 dyn s cm?5, P < 0.01) in group B than group A at presyncope. The steeper fall in cardiac output in group B was due to a drop in heart rate. MSNA decreased rapidly at presyncope after the onset of hypotension. Thus, a moderate fall in cardiac output with coincident vasodilatation or a marked fall in cardiac output with no changes in peripheral vascular resistance may contribute to (pre)syncope. However, an intrinsic impairment of vasomotor responsiveness and sympathetic baroreflex function is not the cause of neurally mediated (pre)syncope in this population.

Fu, Qi; Verheyden, Bart; Wieling, Wouter; Levine, Benjamin D

2012-01-01

24

The relationship between cardiac output and dynamic cerebral autoregulation in humans  

PubMed Central

Cerebral autoregulation adjusts cerebrovascular resistance in the face of changing perfusion pressures to maintain relatively constant flow. Results from several studies suggest that cardiac output may also play a role. We tested the hypothesis that cerebral blood flow would autoregulate independent of changes in cardiac output. Transient systemic hypotension was induced by thigh-cuff deflation in 19 healthy volunteers (7 women) in both supine and seated positions. Mean arterial pressure (Finapres), cerebral blood flow (transcranial Doppler) in the anterior (ACA) and middle cerebral artery (MCA), beat-by-beat cardiac output (echocardiography), and end-tidal Pco2 were measured. Autoregulation was assessed using the autoregulatory index (ARI) defined by Tiecks et al. (Tiecks FP, Lam AM, Aaslid R, Newell DW. Stroke 26: 1014–1019, 1995). Cerebral autoregulation was better in the supine position in both the ACA [supine ARI: 5.0 ± 0.21 (mean ± SE), seated ARI: 3.9 ± 0.4, P = 0.01] and MCA (supine ARI: 5.0 ± 0.2, seated ARI: 3.8 ± 0.3, P = 0.004). In contrast, cardiac output responses were not different between positions and did not correlate with cerebral blood flow ARIs. In addition, women had better autoregulation in the ACA (P = 0.046), but not the MCA, despite having the same cardiac output response. These data demonstrate cardiac output does not appear to affect the dynamic cerebral autoregulatory response to sudden hypotension in healthy controls, regardless of posture. These results also highlight the importance of considering sex when studying cerebral autoregulation.

Deegan, B. M.; Devine, E. R.; Geraghty, M. C.; Jones, E.; OLaighin, G.

2010-01-01

25

Erroneous continuous cardiac output by calibrated pulse contour analysis.  

PubMed

Pulse contour analysis techniques are used for beat-to-beat tracking of cardiac output in critically ill patients. However, an adequate pulse pressure waveform signal and identification of the appropriate (i.e. systolic) part of the waveform by the monitor are crucial for correct calculation of continuous cardiac output. We observed a case where the monitor failed to correctly identify the systolic part of the waveform during tachycardia thus giving false readings. We would like to emphasize the importance of visually checking the waveform for any irregularities that may cause erroneous calculations before initiating a therapy based on these values. One advantage of the system used here is that the part of the pressure curve used for analysis is automatically indicated. PMID:23604580

Grensemann, Jörn; Wappler, Frank; Sakka, Samir G

2013-04-19

26

Rapid cardiac-output measurement with ungated spiral phase contrast  

Microsoft Academic Search

An ungated spiral phase-contrast (USPC) method was used to measure cardiac output (CO) rapidly and conveniently. The USPC method, which was originally designed for small periph- eral vessels, was modified to assess CO by measuring flow in the ascending aorta (AA). The modified USPC used a 12-inter- leaf spiral trajectory to acquire full-image data every 283 ms with 2-mm spatial

Jong B. Park; Bob S. Hu; Steven M. Conolly; Krishna S. Nayak; Dwight G. Nishimura

2006-01-01

27

Errors in the measurement of cardiac output by thermodilution  

Microsoft Academic Search

Cardiac output (CO) determination by thermodilution, which was introduced by Fegler in 1954, has gained wide acceptance in\\u000a clinical medicine and animal experiments because it has several advantages over other methods with respect to simplicity,\\u000a accuracy, reproducibility, repeated measurements at short intervals, and because there is no need for blood withdrawal. However,\\u000a errors in determination of CO by thermodilution may

Toshiaki Nishikawa; Shuji Dohi

1993-01-01

28

Cardiac Output and Central Blood Volume as a Function of Body Weight in the Baboon.  

National Technical Information Service (NTIS)

The relationship between cardiac output and central blood volume as a function of body weight was investigated in tranquilized adult baboons. Cardiac output was determined by the dye dilution method. Central blood volume was calculated as the product of c...

1971-01-01

29

Effect of norepinephrine dosage and calibration frequency on accuracy of pulse contour-derived cardiac output  

Microsoft Academic Search

INTRODUCTION: Continuous cardiac output monitoring is used for early detection of hemodynamic instability and guidance of therapy in critically ill patients. Recently, the accuracy of pulse contour-derived cardiac output (PCCO) has been questioned in different clinical situations. In this study, we examined agreement between PCCO and transcardiopulmonary thermodilution cardiac output (COTCP) in critically ill patients, with special emphasis on norepinephrine

Matthias Gruenewald; Patrick Meybohm; Jochen Renner; Ole Broch; Amke Caliebe; Norbert Weiler; Markus Steinfath; Jens Scholz; Berthold Bein

2011-01-01

30

A comparison of three minimally invasive cardiac output devices with thermodilution in elective cardiac surgery.  

PubMed

This study compared the cardiac output responses to haemodynamic interventions as measured by three minimally invasive monitors (Oesophageal Doppler Monitor the VigileoFlotrac and the LiDCOrapid) to the responses measured concurrently using thermodilution, in cardiac surgical patients. The study also assessed the precision and bias of these monitors in relation to thermodilution measurements. After a fluid bolus of at least 250 ml, the measured change in cardiac output was different among the devices, showing an increase with thermodilution in 82% of measurements, Oesophageal Doppler Monitor 68%, VigileoFlotrac 57% and LiDCOrapid 41%. When comparing the test devices to thermodilution, the kappa statistic showed at best only fair agreement, Oesophageal Doppler Monitor 0.34, LiDCOrapid 0.28 and VigileoFlotrac -0.03. After vasopressor administration, there was also significant variation in the change in cardiac output measured by the devices. Using Bland-Altman analysis, the precision of the devices in comparison to thermodilution showed minimal bias, but wide limits of agreement with percentage errors of Oesophageal Doppler Monitor 64.5%, VigileoFlotrac 47.6% and LiDCOrapid 54.2%. These findings indicate that these three devices differ in their responses, do not always provide the same information as thermodilution and should not be used interchangeably to track cardiac output changes. PMID:22165352

Phan, T D; Kluger, R; Wan, C; Wong, D; Padayachee, A

2011-11-01

31

NRSF regulates the fetal cardiac gene program and maintains normal cardiac structure and function  

PubMed Central

Reactivation of the fetal cardiac gene program is a characteristic feature of hypertrophied and failing hearts that correlates with impaired cardiac function and poor prognosis. However, the mechanism governing the reversible expression of fetal cardiac genes remains unresolved. Here we show that neuron-restrictive silencer factor (NRSF), a transcriptional repressor, selectively regulates expression of multiple fetal cardiac genes, including those for atrial natriuretic peptide, brain natriuretic peptide and ?-skeletal actin, and plays a role in molecular pathways leading to the re-expression of those genes in ventricular myocytes. Moreover, transgenic mice expressing a dominant-negative mutant of NRSF in their hearts exhibit dilated cardiomyopathy, high susceptibility to arrhythmias and sudden death. We demonstrate that genes encoding two ion channels that carry the fetal cardiac currents If and ICa,T, which are induced in these mice and are potentially responsible for both the cardiac dysfunction and the arrhythmogenesis, are regulated by NRSF. Our results indicate NRSF to be a key transcriptional regulator of the fetal cardiac gene program and suggest an important role for NRSF in maintaining normal cardiac structure and function.

Kuwahara, Koichiro; Saito, Yoshihiko; Takano, Makoto; Arai, Yuji; Yasuno, Shinji; Nakagawa, Yasuaki; Takahashi, Nobuki; Adachi, Yuichiro; Takemura, Genzo; Horie, Minoru; Miyamoto, Yoshihiro; Morisaki, Takayuki; Kuratomi, Shinobu; Noma, Akinori; Fujiwara, Hisayoshi; Yoshimasa, Yasunao; Kinoshita, Hideyuki; Kawakami, Rika; Kishimoto, Ichiro; Nakanishi, Michio; Usami, Satoru; Saito, Yoshitomo; Harada, Masaki; Nakao, Kazuwa

2003-01-01

32

Noninvasive Monitoring of Cardiac Output in Critically Ill Patients Using Transesophageal Doppler  

Microsoft Academic Search

Measurement of cardiac output using thermodilution technique in mechanically ventilated patients is associated with significant morbidity. The goal of the present study was to assess the validity of car- diac output measurement using transesophageal Doppler in critically ill patients. Forty-six patients from three different intensive care units underwent 136 paired cardiac output measurements using thermodilution (CO TH ) and transesophageal

BRUNO VALTIER; BERNARD P. CHOLLEY; JEAN-PIERRE BELOT; JOAQUIM MATEO; DIDIER M. PAYEN

1998-01-01

33

Cardiac Output Assessed by Invasive and Minimally Invasive Techniques  

PubMed Central

Cardiac output (CO) measurement has long been considered essential to the assessment and guidance of therapeutic decisions in critically ill patients and for patients undergoing certain high-risk surgeries. Despite controversies, complications and inherent errors in measurement, pulmonary artery catheter (PAC) continuous and intermittent bolus techniques of CO measurement continue to be the gold standard. Newer techniques provide less invasive alternatives; however, currently available monitors are unable to provide central circulation pressures or true mixed venous saturations. Esophageal Doppler and pulse contour monitors can predict fluid responsiveness and have been shown to decrease postoperative morbidity. Many minimally invasive techniques continue to suffer from decreased accuracy and reliability under periods of hemodynamic instability, and so few have reached the level of interchangeability with the PAC.

Lee, Allison J.; Cohn, Jennifer Hochman; Ranasinghe, J. Sudharma

2011-01-01

34

Rapid cardiac-output measurement with ungated spiral phase contrast.  

PubMed

An ungated spiral phase-contrast (USPC) method was used to measure cardiac output (CO) rapidly and conveniently. The USPC method, which was originally designed for small peripheral vessels, was modified to assess CO by measuring flow in the ascending aorta (AA). The modified USPC used a 12-interleaf spiral trajectory to acquire full-image data every 283 ms with 2-mm spatial resolution. The total scan time was 5 s. For comparison, a triggered real-time (TRT) method was used to indirectly calculate CO by measuring left-ventricular (LV) volume. The USPC and TRT measurements from all normal volunteers agreed. In a patient with patent ductus arteriosus (PDA), high CO was measured with USPC, which agreed well with the invasive cardiac-catheterized measurement. In normal volunteers, CO dropped about 20-30% with Valsalva maneuvering, and increased about 100% after exercise. Continuous 28-s cycling between Valsalva maneuvering and free-breathing showed that USPC can temporally resolve physiological CO changes. PMID:16802317

Park, Jong B; Hu, Bob S; Conolly, Steven M; Nayak, Krishna S; Nishimura, Dwight G

2006-08-01

35

Arterial pressure waveform derived cardiac output FloTrac/Vigileo system (third generation software): comparison of two monitoring sites with the thermodilution cardiac output.  

PubMed

The present study was conducted to study the effect of monitoring site, radial or femoral, for arterial pressure waveform derived cardiac output using FloTrac/Vigileo system with third generation software version 3.02 during cardiac surgery. The cardiac output derived from the two sites was also compared to the pulmonary artery catheter (PAC) derived cardiac output to reevaluate the relation between them using the newer software. The effect of cardiopulmonary bypass (CPB) was also studied by doing the sub analysis before and after bypass. Forty patients undergoing coronary artery bypass surgery with cardiopulmonary bypass were enrolled in the study. Cardiac output derived from radial artery (RADCO), femoral artery (FEMCO) using FloTrac/Vigileo system with third generation software version 3.02 and cardiac output using pulmonary artery catheter (PACCO) at predefined nine time points were recorded. Three hundred and forty two cardiac output data triplets were analysed. The Bland-Altman analysis of RADCO and FEMCO revealed a mean bias of -0.28 with percentage error of 20%. The pre CPB precision of both RADCO and FEMCO was 1.25 times as that of PACCO. The post CPB precision of FEMCO was 1.2 times of PACCO while that of RADCO was 1.7 times of PACCO. The third generation of FloTrac/Vigileo system shows good correlation between the radial and femoral derived cardiac outputs in both pre and post bypass periods. The newer software correlates better to PAC derived cardiac output in the post bypass period for femoral artery than radial artery. PMID:22350311

Vasdev, Sumit; Chauhan, Sandeep; Choudhury, Minati; Hote, Millind P; Malik, Madhur; Kiran, Usha

2012-02-17

36

Cardiac Output Measurement by Pulse Dye Densitometry: Comparison with Pulmonary Artery Thermodilution in Post-Cardiac Surgery Patients  

Microsoft Academic Search

Objective. Pulse-dye densitometry (PDD) could be a suitable, low-invasive alternative to thermodilution using a pulmonary artery catheter\\u000a (PAC) for monitoring cardiac output. The aim of our study was to assess the reproducibility and validity of PDD compared to\\u000a PAC-thermodilution. Methods. In 43 post-cardiac surgery patients, the mean of triplicate readings of cardiac output was assessed using both methods.\\u000a In a

Martijn Kroon; A. B. Johan Groeneveld; Yvo M. Smulders

2005-01-01

37

Cardiac output measurement in newborn infants using the ultrasonic cardiac output monitor: an assessment of agreement with conventional echocardiography, repeatability and new user experience  

Microsoft Academic Search

ObjectiveTo assess (1) agreement between the ultrasonic cardiac output monitor (USCOM) 1A device for measurement of cardiac output in newborn infants and conventional echocardiography (ECHO), (2) repeatability of USCOM measurements and (3) agreement between novice and expert users of the USCOM.DesignA prospective observational study.SettingThe Neonatal Unit at the Royal Children's Hospital, Melbourne, Australia.Patients56 term and near-term infants, with no evidence

Neil Patel; Melissa Dodsworth; John F Mills

2011-01-01

38

Cardiac output, blood pressure variability, and cognitive decline in geriatric cardiac patients  

PubMed Central

OBJECTIVE To prospectively investigate whether baseline findings on specific cardiovascular indices are predictive of subsequent rate of decline in Attention-Executive-Psychomotor function in a cohort of ambulatory older adults with cardiovascular diseases (CVDs). METHODS One hundred seventy-two older adults with CVD were administered a neuropsychological battery of executive functions tests at study entry, and at 12 and 36 months thereafter. At study entry, they also underwent vascular assessments including cardiac output (CO), ejection fraction, blood pressure (BP), brachial artery reactivity, and carotid intima media thickness. Random coefficient regressions were used to investigate the effect of these cardiac indices on rate of decline in Attention-Executive-Psychomotor function. RESULTS Cardiac output, systolic BP variability, and diastolic BP variability predicted decline in Attention-Executive-Psychomotor function. Specifically, lower CO, reduced variability in systolic BP, and increased variability in diastolic BP were associated with a faster rate of decline in Attention-Executive-Psychomotor function. Mean resting systolic and diastolic blood pressure did not predict decline in Attention-Executive-Psychomotor function. CONCLUSION Decline in frontal-subcortical cognitive functions among patients with CVDs appears to be mediated by systemic hypoperfusion and variability in blood pressure. The precise nature of these relationships, especially with regard to blood pressure variability, is complex and demands continued investigation.

Okonkwo, Ozioma C.; Cohen, Ronald A.; Gunstad, John; Poppas, Athena

2011-01-01

39

Non-invasive cardiac output monitoring during catheter interventions in patients with cavopulmonary circulations.  

PubMed

Introduction: Functionally univentricular hearts palliated with superior or total cavopulmonary connection result in circulations in series. The absence of a pre-pulmonary pump means that cardiac output is more difficult to adjust and control. Continuous monitoring of cardiac output is crucial during cardiac catheter interventions and can provide new insights into the complex physiology of these lesions. Materials and methods: The Icon® cardiac output monitor was used to study the changes in cardiac output during catheter interventions in 15 patients (median age: 6.1 years, range: 4.8-15.3 years; median weight: 18.5 kg, range: 15-63 kg) with cavopulmonary circulations. A total of 19 interventions were undertaken in these patients and the observed changes in cardiac output were recorded and analysed. Results: Cardiac output was increased with creation of stent fenestrations after total cavopulmonary connection (median increase of 22.2, range: 6.7%-28.6%) and also with drainage of significant pleural effusions (16.7% increase). Cardiac output was decreased with complete or partial occlusion of fenestrations (median decrease of 10.6, range: 7.1%-13.4%). There was a consistent increase in cardiac output with stenting of obstructive left pulmonary artery lesions (median increase of 7.7, range: 5%-14.3%, p = 0.007). Conclusions: Icon® provides a novel technique for the continuous, non-invasive monitoring of cardiac output. It provides a further adjunct for monitoring of physiologically complex patients during catheter interventions. These results are consistent with previously reported series involving manipulation of fenestrations. This is the first report identifying an increase in cardiac output with stenting of obstructive pulmonary arterial lesions. PMID:23680531

Noonan, Patrick Michael Emmet; Viswanathan, Sangeetha; Chambers, Amy; Stumper, Oliver

2013-05-17

40

Equipment review: An appraisal of the LiDCO(TM)plus method of measuring cardiac output  

PubMed Central

The LiDCO™plus system is a minimally/non-invasive technique of continuous cardiac output measurement. In common with all cardiac output monitors this technology has both strengths and weaknesses. This review discusses the technological basis of the device and its clinical application.

2004-01-01

41

The effects of chronic prostacyclin therapy on cardiac output and symptoms in primary pulmonary hypertension  

Microsoft Academic Search

OBJECTIVESThis study evaluated the response to prostacyclin dose reduction in patients with primary pulmonary hypertension (PPH) who developed high cardiac outputs.BACKGROUNDPatients on prostacyclin require chronic upward dose titration to overcome tolerance to the medication. No upper limit of effective dose has been described.METHODSWe studied 12 patients with PPH treated with chronic prostacyclin therapy who presented in high cardiac output states.

Stuart Rich; Vallerie V McLaughlin

1999-01-01

42

Feasibility and variability of six methods for the echocardiographic and Doppler determination of cardiac output  

Microsoft Academic Search

The feasibility and the intrinsic variability of six different methods of echocardiographic and Doppler flow determination of cardiac output were analysed in 34 healthy volunteers. Four were excluded because of poor quality echocardiograms. The mean (range) age of the remaining 30 (12 women, 18 men) was 21 years (13-36 years). Cardiac output was calculated by six methods as a product

G L Nicolosi; E Pungercic; E Cervesato; D Pavan; L Modena; E Moro; V DallAglio; D Zanuttini

1988-01-01

43

The relationship between the flow of arteriovenous fistula and cardiac output in haemodialysis patients  

Microsoft Academic Search

Background. Satisfactory haemodialysis (HD) vascular access flow (Qa) is necessary for dialysis adequacy. High Qa is postulated to increase cardiac output (CO) and cause high-output cardiac failure. Aim of the present prospective study was to evaluate the relation- ship between Qa of arteriovenous fistulas (AVFs) and CO in order to have a closer insight into this scarcely explored aspect of

Carlo Basile; Carlo Lomonte; Luigi Vernaglione; Francesco Casucci; Maurizio Antonelli; Nicola Losurdo

2008-01-01

44

Measurement of Stroke Volume and Cardiac Output Using Echocardiography and Doppler  

Microsoft Academic Search

\\u000a Cardiac output measurement is of prime importance in the hemodynamic assessment of patients with circulatory failure. It helps\\u000a distinguish the different types of shock and, more importantly, is crucial in discriminating between cardiac dysfunction and\\u000a failure and also in evaluating the impact of various interventions.\\u000a \\u000a \\u000a Different methods can be used to measure cardiac output or, more precisely, stroke volume since

Bernard P. Cholley

45

Gastric intramucosal pH: A predictor of survival in cardiac surgery patients with low cardiac output?  

Microsoft Academic Search

Objective: To assess the value of gastric intramucosal pH measurement in patients with low output after cardiac surgery.Design: Prospective clinical study.Setting: University hospital.Participants: Fifteen patients with low output after cardiac surgery were included. Those who survived the first postoperative day (n = 14) remained in the study.Interventions: Gastric intramucosal pH and arterial lactate concentrations were measured 6, 12, and 24

Hubert Böhrer; Heinfried Schmidt; Johann Motsch; René Gust; Alfons Bach; Eike Martin

1997-01-01

46

Continuous monitoring of cardiac output from TCG signals.  

PubMed

Continuous measurement of cardiac output (CO) is an important and difficult measure to obtain in an ambulatory environment. A novel ambulatory monitoring system (LifeShirt, VivoMetrics, Inc., Ventura, CA, USA) with three Inductive Plethysmographic (IP) sensors embedded in a garment, enables continuous monitoring of respiration from the ribcage and abdomen areas, and captures thoracocardiograph (TCG) signals from the thorax at the level of the left ventricle. This TCG signal provides a non-invasive measure of the volumetric contractions of the heart. The raw TCG signal must undergo extensive signal processing and digital filtering to extract a volume curve similar to the ventricular volume curve obtained through echocardiography. Typically the respiratory component has an amplitude of over twenty times that of the stroke volume curve. This investigation compares various signal processing algorithms such as spectral subtraction and adaptive filtering to separate these 2 components, which can occupy the same frequency band. These algorithms make use of the ribcage and abdominal signals to predict the respiratory component within the TCG signal. A dual axis accelerometer that measures posture and levels of activity aids filtering movement artifact. With the addition of a single lead ECG, ensemble averaging is used to smooth artifact in the signal, and CO may be obtained by including a heart rate measure. Additional measures can be derived including left ventricular systolic time intervals such as Pre-ejection period, Peak ejection rate and time to peak ejection rate. The results show that increases and decreases in SV and CO can be measured over time. PMID:15133982

Keenan, D B

2004-01-01

47

Comparison of bedside measurement of cardiac output with the thermodilution method and the Fick method in mechanically ventilated patients  

Microsoft Academic Search

INTRODUCTION: Bedside cardiac output determination is a common preoccupation in the critically ill. All available methods have drawbacks. We wished to re-examine the agreement between cardiac output determined using the thermodilution method (QTTHERM) and cardiac output determined using the metabolic (Fick) method (QTFICK) in patients with extremely severe states, all the more so in the context of changing practices in

Jésus Gonzalez; Christian Delafosse; Muriel Fartoukh; André Capderou; Christian Straus; Marc Zelter; Jean-Philippe Derenne; Thomas Similowski

2003-01-01

48

Lithium Dilution Cardiac Output Measurements Using a Peripheral Injection Site: Comparison with Central Injection Technique and Thermodilution  

Microsoft Academic Search

Objective. The lithium dilution technique for the measurement of cardiac output by the central injection of lithium chloride was introduced by Linton et al. in 1993. In the present report, we compare lithium dilution cardiac output measurement (LD) by the peripheral injection of lithium chloride (pLD) and by central venous injection (cLD), cardiac output determined by electromagnetic flowmetry (EM), and

Tadayoshi Kurita; Koji Morita; Shigeru Kato; Hiroyuki Kawasaki; Mutsuhito Kikura; Tomiei Kazama; Kazuyuki Ikeda

1999-01-01

49

Intensive insulin therapy to maintain normoglycemia after cardiac surgery.  

PubMed

Drugs used in the perioperative period could have an effect on survival as recently pointed out by an international consensus conference on the reduction in mortality in cardiac anesthesia and intensive care. Insulin infusion to achieve a strict glycemic control is the best example of how an ancillary (i.e. non-surgical) drug/technique/strategy might influence survival rates in patients undergoing cardiac surgery. The author of this "expert opinion" presents her insights into the use of insulin in this setting and suggest that based on available evidence based medicine, insulin infusion, titrated to "normoglycemia" is a complex intervention, that not only requires the simple administration of a "drug", the hormone insulin, but also needs tools and skills to accurately measure and control blood glucose to achieve normoglycemia while avoiding hypoglycemia and large glucose fluctuations. PMID:23439402

Van den Berghe, G

2011-01-01

50

Health Technology Assessment Reports, 1989. Number 3. Cardiac Output by Electrical Bioimpedance.  

National Technical Information Service (NTIS)

Electrical bioimpedance is a method used to determine stroke volume and cardiac output from thoracic tissue resistance to an imposed alternating electric current. The tissue resistance is inversely related to the thoracic blood content. When thoracic bloo...

H. Handelsman

1989-01-01

51

Comparison of dye dilution method to radionuclide techniques for cardiac output determination in dogs  

SciTech Connect

A study was undertaken to identify the most accurate /sup 99m/Tc-labeled radiopharmaceutical and to determine the accuracy of a noninvasive radionuclide technique or cardiac output determinations. Phase I employed sodium pertechnetate, stannous pyrophosphate with sodium pertechnetate, /sup 99m/Tc red blood cells, and /sup 99m/Tc human serum albumin as radionuclide tracers. Cardiac output was determined by the dye dilution method and then by the invasive radionuclide technique. A pairied t test and regression analysis indicated that /sup 99m/Tc human serum albumin was the most accurate radiopharmaceutical for cardiac output determinations, and the results compared favorably to those obtained by the dye dilution method. In Phase II, /sup 99m/Tc human serum albumin was used as the radionuclide tracer for cardiac output determinations with the noninvasive technique. The results compared favorably to those obtained by the dye dilution method.

Eng, S.S.; Robayo, J.R.; Porter, W.; Smith, R.E.

1980-05-01

52

Validation of a Modified One-Step Rebreathing Technique for Measuring Exercise Cardiac Output.  

National Technical Information Service (NTIS)

A modification of the Farhi one-step rebreathing technique is described for determining submaximal exercise cardiac output (Q). Factors critical in the estimation of Q are initial rebreathing bag volume and constant bag volume during the maneuver. By subs...

P. C. Szlyk K. C. Evans I. V. Sils

1988-01-01

53

Improvements in determination of cardiac output with a Swan-Ganz catheter.  

PubMed

The time constant for heat transfer may affect exact determination of cardiac output with Swan-Ganz catheters. Commercially available Swan-Ganz catheters are provided with thermistors with varying time constants. Current monitoring of cardiac output is not corrected for these time constants, so the conventional method of determining cardiac output using the equation of Stewart-Hamilton produces marked errors. The authors propose a new method of determining cardiac output with Swan-Ganz catheters with varying time constants from thermal dilution curve data based on Newton's cooling law. Values for blood flow rate determined by the new method using a completely stirred tank of original design, mimicking the natural heart and using bovine blood, are almost the same as values observed at varying saline infusion volumes, saline temperatures, and saline infusion times. PMID:2252783

Sakagami, M; Kuwana, K; Nakanishi, H; Sakai, K

54

Continuous measurement of cardiac output with the use of stochastic system identification techniques  

Microsoft Academic Search

The limitations of developing a technique to measure cardiac output continuously are given. Logical explanations are provided\\u000a for the economic, technical, and physiologic benefits of a stochastic system identification technique for measuring cardiac\\u000a output. Heat is supplied by a cathetermounted filament driven according to a pseudorandom binarsequence. Volumetric fluid\\u000a flow is derived by a crosscorrelation algorithm written in the C

Mark Yelderman

1990-01-01

55

Measurement of extravascular lung water by thermal-dye dilution technique: Mechanisms of cardiac output dependence  

Microsoft Academic Search

The extent to which extravascular lung water (EVLW) is dependent on cardiac output was analysed in anaesthetized and mechanically ventilated pigs. EVLW was measured by thermal-dye dilution technique, by a fibreoptic thermistor catheter system (system 1), and by a thermistor catheter-external optical cuvette system (system 2). During baseline conditions, at which cardiac output was 3.65 l\\/min, EVLW was 11.7 and

C.-J. Wickerts; J. Jakobsson; C. Frostell; G. Hedenstierna

1990-01-01

56

Volume loading improves low cardiac output in experimental right ventricular infarction. [Dogs  

SciTech Connect

To evaluate the effect of volume loading in the low output state associated with right ventricular infarction, isolated right ventricular infarction was produced in seven dogs with the pericardium intact. Volume loading and pericardiotomy were then sequentially performed. After the production of right ventricular infarction, right ventricular systolic pressure decreased by 25%, aortic pressure by 36% and cardiac output by 32%. Right ventricular ejection fraction decreased by 57%, but left ventricular ejection fraction did not change significantly. Left ventricular transmural pressure and diastolic size decreased, and right ventricular diastolic size increased. Intrapericardial pressure increased and equalization of diastolic pressures was noted. Volume loading resulted in increased right ventricular systolic pressure and stroke work, increased aortic pressure and cardiac output and increased transmural pressure and diastolic size in both ventricles. Pericardiotomy resulted in further increases in right and left ventricular filling, stroke work and cardiac output, as well as resolution of equalized diastolic pressures. These results indicate that cardiac output in experimental right ventricular infarction increases with volume loading, which enhances left ventricular preload by augmenting right ventricular output. Elevated intrapericardial pressure affects filling of both ventricles and may play a role in the pathophysiology of low cardiac output in right ventricular infarction.

Goldstein, J.A.; Vlahakes, G.J.; Verrier, E.D.; Schiller, N.B.; Botvinick, E.; Tyberg, J.V.; Parmley, W.W.; Chatterjee, K.

1983-08-01

57

Techniques for maintaining design efficiency when operating klystron amplifiers at levels below the maximum output power  

NASA Astrophysics Data System (ADS)

Some accelerator designs require that the amount of RF power supplied to the accelerating cavities be varied along the accelerator length. In order to minimize operating expense for a high-power, CW system, it is also desirable to maximize RF-generator efficiency. Klystrons are the traditional source used for RF-accelerator applications, but a high-efficiency klystron design is optimized to provide high efficiency at only one operating point, usually at saturation. Different klystron designs could be used for different power levels to maintain high efficiency; however, this approach would increase the capital costs of the accelerator. We discuss several methods of varying the output power of a klystron and show semi-empirically a way to preserve klystron efficiency. We derive two semi-empirical methods to predict the variations in power and efficiency under nonoptimum operating conditions. Experimental data from a 1.25 MW klystron are also shown. These data support our hypothesis and our models.

Tallerico, Paul; Rees, Daniel; Young, Andrew; Laycock, Don; Symons, Robert

1995-04-01

58

Cardiac Output Derived from Arterial Pressure Waveform Analysis in Patients Undergoing Cardiac Surgery: Validity of a Second Generation Device  

Microsoft Academic Search

BACKGROUND: The performance of a recently introduced, arterial waveform-based device for measuring cardiac output (CO) without the need of invasive calibration (FloTrac\\/Vigileo™) has been controversial. We designed the present study to assess the validity of an improved version of this monitoring technique compared with intermittent thermodilution CO measurement using a pulmonary artery catheter in patients undergoing cardiac surgery. METHODS: Forty

Jochen Mayer; Joachim Boldt; Michael W. Wolf; Johannes Lang; Stefan Suttner

2008-01-01

59

Non-invasive measurement of cardiac output by a single breath constant expiratory technique.  

PubMed Central

A new single breath test has been developed that measures pulmonary blood flow (Qc) and pulmonary tissue volume by using the fact that Qc is proportional to the relationship between the absorption rate of acetylene (C2H2) from the alveolar gas and the rate of change of lung volume during constant expiratory flow. To make these measurements a bag in bottle system with a rolling seal spirometer, a mass spectrometer, and a minicomputer with analogue to digital conversion have been used. Qc was compared with cardiac output measured by the thermodilution technique in 20 patients with cardiac disease; some also had mild chronic obstructive pulmonary disease. The mean (SD) resting Qc for the group was 5.27 (1.22) l/min and the cardiac output measured by thermodilution was 5.30 (1.31) l/min. The mean difference between the two estimations of cardiac output was 0.03 l and the standard deviation of this difference was 0.76 l. The Qc technique was not successful in patients with an FEV1/FVC less than 60%, but seemed to be accurate in those with higher FEV1/FVC values. Correction of Qc for the effect of venous admixture in 14 patients resulted in an average 19% overestimation of cardiac output (6.01 (2.52) l/min v 5.05 (1.64) l/min). It is concluded that cardiac output can be accurately measured in patients with cardiac or mild pulmonary disease. No correction for venous admixture due to ventilation-perfusion mismatch was necessary in these patients, presumably because the large breath used by the technique overcomes most mild ventilation-perfusion maldistribution. These findings, in addition to the non-invasive nature of the technique, suggest potential value for the measurement of cardiac output in various clinical conditions. Images

Elkayam, U; Wilson, A F; Morrison, J; Meltzer, P; Davis, J; Klosterman, P; Louvier, J; Henry, W L

1984-01-01

60

The uncalibrated pulse contour cardiac output during off-pump coronary bypass surgery: performance in patients with a low cardiac output status and a reduced left ventricular function  

PubMed Central

Background We compared the continuous cardiac index measured by the FloTrac/Vigileo™ system (FCI) to that measured by a pulmonary artery catheter (CCI) with emphasis on the accuracy of the FCI in patients with a decreased left ventricular ejection fraction (LVEF) and a low cardiac output status during off-pump coronary bypass surgery (OPCAB). We also assessed the influence of several factors affecting the pulse contour, such as the mean arterial pressure (MAP), the systemic vascular resistance index (SVRI) and the use of norepinephrine. Methods Fifty patients who were undergoing OPCAB (30 patients with a LVEF ? 40%, 20 patients with a LVEF < 40%) were enrolled. The FCI and CCI were measured and we performed a Bland-Altman analysis. Subgroup analyses were done according to the LVEF (< 40%), the CCI (? 2.4 L/min/m), the MAP (60-80 mmHg), the SVRI (1,600-2,600 dyne/s/cm5/m2) and the use of norepinephrine. Results The FCI was reliable at all the time points of measurement with an overall bias and limit of agreement of -0.07 and 0.67 L/min/m2, respectively, resulting in a percentage error of 26.9%. The percentage errors in the patients with a decreased LVEF and in a low cardiac output status were 28.2% and 22.3%, respectively. However, the percentage error in the 91 data pairs outside the normal range of the SVRI was 40.2%. Conclusions The cardiac output measured by the FloTrac/Vigileo™ system was reliable even in patients with a decreased LVEF and in a low cardiac output status during OPCAB. Acceptable agreement was also noted during the period of heart displacement and grafting of the obtuse marginalis branch.

Jo, Youn Yi; Song, Jong Wook; Yoo, Young Chul; Park, Ji Young; Kwak, Young Lan

2011-01-01

61

Cardiac power output and its response to exercise in athletes and non-athletes.  

PubMed

Cardiac power output (CPO) is an integrative measure of overall cardiac function as it accounts for both, flow- and pressure-generating capacities of the heart. The purpose of the present study was twofold: (i) to assess cardiac power output and its response to exercise in athletes and non-athletes and (ii) to determine the relationship between cardiac power output and reserve and selected measures of cardiac function and structure. Twenty male athletes and 32 age- and gender-matched healthy sedentary controls participated in this study. CPO was calculated as the product of cardiac output and mean arterial pressure, expressed in watts. Measures of hemodynamic status, cardiac structure and pumping capability were assessed by echocardiography. CPO was assessed at rest and after peak bicycle exercise. At rest, the two groups had similar values of cardiac power output (1·08 ± 0·2 W versus 1·1 ± 0·24 W, P>0·05), but the athletes demonstrated lower systolic blood pressure (109·5 ± 6·2 mmHg versus 117·2 ± 8·2 mmHg, P<0·05) and thicker posterior wall of the left ventricle (9·8 ± 1 mm versus 9 ± 1·1 mm, P<0·05). Peak CPO was higher in athletes (5·87 ± 0·75 W versus 5·4 ± 0·69 W, P<0·05) as was cardiac reserve (4·92 ± 0·66 W versus 4·26 ± 0·61 W, P<0·05), respectively. Peak exercise CPO and reserve were only moderately correlated with end-diastolic volume (r = 0·54; r = 0·46, P<0·05) and end-diastolic left ventricular internal diameter (r = 0·48; r = 0·42, P<0·05), respectively. Athletes demonstrated greater maximal cardiac pumping capability and reserve than non-athletes. The study provides new evidence that resting measures of cardiac structure and function need to be considered with caution in interpretation of maximal cardiac performance. PMID:23522013

Klasnja, Aleksandar V; Jakovljevic, Djordje G; Barak, Otto F; Popadic Gacesa, Jelena Z; Lukac, Damir D; Grujic, Nikola G

2012-12-13

62

Comparison of uncalibrated arterial waveform analysis in cardiac surgery patients with thermodilution cardiac output measurements  

PubMed Central

Introduction Cardiac output (CO) monitoring is indicated only in selected patients. In cardiac surgical patients, perioperative haemodynamic management is often guided by CO measurement by pulmonary artery catheterisation (COPAC). Alternative strategies of CO determination have become increasingly accepted in clinical practice because the benefit of guiding therapy by data derived from the PAC remains to be proven and less invasive alternatives are available. Recently, a device offering uncalibrated CO measurement by arterial waveform analysis (COWave) was introduced. As far as this approach is concerned, however, the validity of the CO measurements obtained is utterly unclear. Therefore, the aim of this study was to compare the bias and the limits of agreement (LOAs) (two standard deviations) of COWave at four specified time points prior, during, and after coronary artery bypass graft (CABG) surgery with a simultaneous measurement of the gold standard COPAC and aortic transpulmonary thermodilution CO (COTranspulm). Methods Data from 30 patients were analysed during this prospective study. COPAC, COTranspulm, and COWave were determined in all patients at four different time points prior, during, and after CABG surgery. The COPAC and the COTranspulm were measured by triple injection of 10 ml of iced isotone sodium chloride solution into the central venous line of the PAC. Measurements of COWave were simultaneously taken at these time points. Results The overall correlation showed a Spearman correlation coefficient between COPAC and COWave of 0.53 (p < 0.01) and 0.84 (p < 0.01) for COPAC and COTranspulm. Bland-Altman analysis showed a mean bias and LOAs of 0.6 litres per minute and -2.2 to +3.4 litres per minute for COPAC versus COWave and -0.1 litres per minute and -1.8 to +1.6 litres per minute for COPAC versus COTranspulm. Conclusion Arterial waveform analysis with an uncalibrated algorithm COWave underestimated COPAC to a clinically relevant extent. The wide range of LOAs requires further evaluation. Better results might be achieved with an improved new algorithm. In contrast to this, we observed a better correlation of thermodilution COTranspulm and thermodilution COPAC measurements prior, during, and after CABG surgery.

Sander, Michael; Spies, Claudia D; Grubitzsch, Herko; Foer, Achim; Muller, Marcus; von Heymann, Christian

2006-01-01

63

Validation of a new spectrometer for noninvasive measurement of cardiac output  

NASA Astrophysics Data System (ADS)

Acetylene is a blood-soluble gas and for many years its uptake rate during rebreathing tests has been used to calculate the flow rate of blood through the lungs (normally equal to cardiac output) as well as the volume of lung tissue. A new, portable, noninvasive instrument for cardiac output determination using the acetylene uptake method is described. The analyzer relies on nondispersive IR absorption spectroscopy as its principle of operation and is configured for extractive (side-stream) sampling. The instrument affords exceptionally fast (30 ms, 10%-90%, 90%-10%, at 500 mL min-1 flow rates), interference-free, simultaneous measurement of acetylene, sulfur hexafluoride (an insoluble reference gas used in the cardiac output calculation), and carbon dioxide (to determine alveolar ventilation), with good (typically +/-2% full-scale) signal-to-noise ratios. Comparison tests with a mass spectrometer using serially diluted calibration gas samples gave excellent (R2>0.99) correlation for all three gases, validating the IR system's linearity and accuracy. A similar level of agreement between the devices also was observed during human subject C2H2 uptake tests (at rest and under incremental levels of exercise), with the instruments sampling a common extracted gas stream. Cardiac output measurements by both instruments were statistically equivalent from rest to 90% of maximal oxygen consumption; the physiological validity of the measurements was confirmed by the expected linear relationship between cardiac output and oxygen consumption, with both the slope and intercept in the published range. These results indicate that the portable, low-cost, rugged prototype analyzer discussed here is suitable for measuring cardiac output noninvasively in a point-of-care setting.

Baum, Marc M.; Kumar, Sasi; Moss, John A.; Wagner, Peter D.

2004-07-01

64

Epi-aortic Doppler measurement of cardiac output in univentricular connection  

PubMed Central

Background In the initial postoperative period after a Fontan-type operation for a univentricular circulation, cardiac output information is important, but cannot be provided by conventional methods due to the surgical reconstruction of the heart. In this regard we investigated the feasibility of epi-aortic Doppler measurements in order to calculate cardiac output. Methods : Epi-aortic cardiac output measurement was compared with Fick measurements as the gold standard in eight patients with a univentricular circulation after a Fontan-type operation. Results The mean diameter of the aorta by epi-aortic measurement was 18 mm (range 14 to 25), by angiography 17 mm (range 10 to 24), correlation coefficient 0.88 (p < 0.05). The mean cardiac output by epi-aortic measurement was 2.8 l.min?1 (range 1.2 to 6.3), by the Fick calculations 1.8 l.min?1 (range 0.8 to 5.0). The correlation coefficient for cardiac output data in aortic diameters up to 20 millimeter in diameter was 0.55 (p < 0.05). Conclusions Epi-aortic Doppler measurement of cardiac output after Fontan type reconstructions could be applied in aortas up to 20 millimeter in diameter. A reasonable correlation with Fick calculations was found. This was supported by Bland–Altman plotting. The method is intrinsically invasive, but application and removal of the device were easy and no complications related to the system were observed. An important restriction is the often present abnormal anatomy, either congenitally or after surgery.

Bogers, Ad J J C; van den Burg, Martin; Schepp, Ronald; Klein, Jan

2009-01-01

65

Peak Cardiac Power Output, Measured Noninvasively, Is a Powerful Predictor of Outcome in Chronic Heart Failure  

Microsoft Academic Search

Background—The cardiac output (CO) response to exercise and other invasively derived hemodynamic variables has been variably described to provide better prognostication than peak VO2 in patients with chronic heart failure. Using noninvasive measurements of CO during exercise, we compared the prognostic value of peak CO and cardiac power to peak VO2 in chronic heart failure patients. Method and Results—One hundred

Chim C. Lang; Paula Karlin; Jennifer Haythe; Tiong K. Lim; Donna M. Mancini

2010-01-01

66

Cardiac output variations in supine resting subjects during head-out cold water immersion  

Microsoft Academic Search

Five men, aged 31.2 years (SD 2.3), under semi-nude conditions and resting in a dorsal reclining position, were exposed to thermoneutral air for 30 min, followed immediately by a cold water (15°C) immersion for 60 min. Cardiac output was measured using a dualbeam Doppler flow meter. During immersion in cold water, cardiac frequency (fc) showed an initial bradycardia. The lowest

P. Vogelaere; G. Deklunder; J. Lecroart

1995-01-01

67

Comparison between Flotrac-Vigileo and Bioreactance, a totally noninvasive method for cardiac output monitoring  

Microsoft Academic Search

ABSTRACT: INTRODUCTION: This study was designed to compare the clinical acceptability of two cardiac output (CO) monitoring systems: a pulse wave contour-based system (FloTrac-Vigileo) and a bioreactance-based system (NICOM), using continuous thermodilution (PAC-CCO) as a reference method. METHODS: Consecutive patients, requiring PAC-CCO monitoring following cardiac surgery, were also monitored by the two other devices. CO values obtained simultaneously by the

Sophie Marqué; Alain Cariou; Jean-Daniel Chiche; Pierre Squara

2009-01-01

68

Cardiac output monitoring: aortic transpulmonary thermodilution and pulse contour analysis agree with standard thermodilution methods in patients undergoing lung transplantation  

Microsoft Academic Search

Purpose  The PiCCO System is a relatively new device allowing intermittent cardiac output monitoring by aortic transpulmonary thermodilution\\u000a technique (Aorta intermittent) and continuous cardiac output monitoring by pulse contour analysis (Aorta continuous). The\\u000a objective of this study was to assess the level of agreement of Aorta intermittent and Aorta continuous with intermittent\\u000a (PA intermittent) and continuous cardiac output (PA continuous) measured

Giorgio Della Rocca; Maria Gabriella Costa; Cecilia Coccia; Livia Pompei; Pierangelo Di Marco; Vincenzo Vilardi; Paolo Pietropaoli

2003-01-01

69

Effects of cardiac output on disposition kinetics of sorbitol: recirculatory modelling.  

PubMed

1. The purpose of this study was to determine the effects of cardiac output on distribution and elimination kinetics of the marker compound sorbitol. 2. The disposition kinetics of sorbitol were investigated after rapid intravenous injection and arterial sampling in nine patients who had undergone cardiac catheterization whereby the cardiac output was measured. 3. A minimal circulatory model consisting of pulmonary and systemic subsystems, both of which were characterized by an inverse Gaussian transit time density function, fitted the data very well. The method involves numerical inverse Laplace transform of the model equations. 4. The mixing clearance introduced as a novel non-compartmental parameter of distribution dynamics was significantly correlated with cardiac output. The steady-state volume of 14 l matched the extracellular volume. The systemic extraction ratio of 23% may reflect the fractional liver blood flow. 5. This pharmacokinetic model can be applied when an independent observation of cardiac output is available. In contrast to the conventional compartmental (or sum of exponential) approach it contains fewer adjustable parameters which can be more readily interpreted in physiological terms. PMID:8730970

Weiss, M; Hübner, G H; Hübner, I G; Teichmann, W

1996-04-01

70

Assessment of a cardiac output device using arterial pulse waveform analysis, Vigileo, in cardiac surgery compared to pulmonary arterial thermodilution.  

PubMed

Many devices are available to assess cardiac output (CO) in critically ill patients and in the operating room. Classical CO monitoring via a pulmonary artery catheter involves continuous cardiac output (CCO) measurement. The second generation of Flotrac/Vigileo monitors propose an analysis of peripheral arterial pulse waves to calculate CO (APCO) without calibration. The aim of our study was to compare the CO between the Swan Ganz catheter and the VigileoT. In this observational study, nine patients undergoing coronary artery bypass grafting were prospectively included. APCO, mean (CCO) and instantaneous CO (ICO) were measured. Perioperative and postoperative assessments were performed up to 24 hours post-surgery. Measurements were recorded every minute, resulting in the collection of 6492 data pairs. Comparison of APCO and ICO showed a limited bias of -0.1 l/min but an important percentage error of 48%. Corresponding values were -0.1 l/min and 46% for the APCO versus CCO comparison, and 0 and 17% for ICO versus CCO comparison. Large inter-individual variability does exist. During cardiac surgery and after leaving the operating room, Vigileo is not clinically equivalent to continuous thermodilution by pulmonary artery catheter Nevertheless, the connection between CCO and ICO relates the difference between APCO and CCO more to the different algorithms used. Further efforts should be concentrated on assessing the ability of this device to track changes in cardiac output. PMID:20369763

Hamm, J B; Nguyen, B V; Kiss, G; Wargnier, J P; Jauffroy, A; Helaine, L; Arvieux, C C; Gueret, G

2010-03-01

71

Lack of reliability of cardiac output measurements derived from arterial pressure waveform analysis in on-pump cardiac surgery patients  

Microsoft Academic Search

\\u000a The arterial pressure waveform-based device for cardiac output (CO) measurement FloTrac\\/VigileoTM offers the possibility of minimal-invasive CO monitoring without the need for invasive calibration. The agreement of the\\u000a results of this device with bolus thermodilution remains controversialas is the choice of the best arterial cannulation site.\\u000a \\u000a \\u000a After approval of the local ethics committee 14 Patients scheduled for elective cardiac surgery

S. Eleftheriadis; M. Heringlake; K.-U. Berger; H. V. Groesdonk; J. Schoen

72

Distribution of cardiac output during pentobarbital versus midazolam\\/fentanyl\\/fluanisone anaesthesia in the rat  

Microsoft Academic Search

Summary Differences in effects on central haemodynamics, organ blood flow, and serum corticosterone were studied in 11 rats anaesthetized with midazolam\\/ fentanyl\\/fluanisone (MFF) and 11 other rats anaesthetized with sodium pentobarbital. Compared with pentobarbital, MFF reduced aortic blood pressure by 250\\/0, increased heart rate by 20%, and increased cardiac output by 80%. Unlike most tissues, MFF produced a fivefold increase

Knut C. Skolleborg; Jon E. Grönbech; Ketil Grong; Frank E. Åbyholm; Jon Lekven

1990-01-01

73

Cardiac output distribution and uteroplacental blood flow in the pregnant rabbit: a comparative study  

SciTech Connect

This study presents data on cardiac output distribution and uterine and placental blood flows in pregnant rabbits under chronic steady-state conditions. Ten litters and 67 fetuses were studied at 29 days of gestation, by means of radioactive microspheres. Five nonpregnant female animals were also studied for comparison. Mean cardiac outputs were 747.16 +/- 55.7 and 613.80 +/- 63.76 ml/min in the pregnant and nonpregnant states, respectively. In the pregnant animals, uterine and mammary blood flows were 6.7% +/- 0.7% and 5.1% +/- 0.5% of cardiac output, respectively. Within litters, the highest placental blood flows occurred at the ovarian and vaginal ends of the uterine horn. Placental blood flow per gram of fetus was 0.106 +/- 0.008 ml X min-1 X gm-1. A comparison with analogous data in the guinea pig and sheep demonstrates that toward the end of pregnancy placental blood flow per gram of fetus is approximately 2.5-times higher in sheep than in rabbits and guinea pigs. Expressed as a percentage of cardiac output, near-term uterine blood flow is significantly less in rabbits than in guinea pigs and sheep, whereas mammary blood flow is significantly higher. These interspecies differences are related to differences in placental structure, fetal/maternal mass ratio, and maturity at birth.

Johnson, R.L.; Gilbert, M.; Meschia, G.; Battaglia, F.C.

1985-03-01

74

Effect of region of interest selection on first-pass radionuclide cardiac output determination  

SciTech Connect

In principle, region of interest (ROI) selection should not affect the measurement of cardiac output by the first-pass technique with a radioactive intravascular indicator. Clinical application of the method requires that this theoretical hypothesis be tested. Sixty-eight left anterior oblique first-pass studies were acquired with a scintillation camera and computer using red blood cells labeled in vitro with /sup 99m/Tc. Calculated mean cardiac output varied in the following order with respect to ROI: lung greater than right heart greater than left ventricle greater than whole heart (both ventricles) greater than aorta. Similar variations were observed in patients both with and without valvular regurgitation. Regions of interest over left ventricle or whole heart yielded the best correlations with cardiac output by thermodilution (r = 0.96, 0.95, respectively, n = 28) as well as the smallest interobserver variations (r = 0.994, 0.995, respectively, n = 33). First-pass studies with (/sup 99m/Tc)red blood cells labeled in vitro can yield accurate, reproducible determinations of cardiac output provided that the effect of ROI selection is recognized and that regions are properly selected.

Glass, E.C.; Rahimian, J.; Hines, H.H.

1986-08-01

75

Improvement of cardiac output estimation by the thermodilution method during mechanical ventilation  

Microsoft Academic Search

The reliability of cardiac output estimation by thermodilution during artificial ventilation was studied in anesthetized pigs at the right side of the heart. The estimates exhibited a cyclic modulation related to the ventilation. The amplitude of the modulation was independent of the level of positive end-expiratory pressure, ventilatory pattern and volemic loading of the animals. However, a non-constant phase relation

J. R. C. Jansen; A. Versprille

1986-01-01

76

Precision of bolus thermodilution cardiac output measurements in patients with atrial fibrillation  

Microsoft Academic Search

Background: The precision of bolus thermodilution cardiac output measurements in patients with atrial fibrillation (AF) has not previously been determined. A priori we suspected that the precision would be lower in patients with AF than in patients with sinus rhythm (SR). Consequently, we also deter- mined if the precision could be improved by injecting the thermal indicator into the right

M. ØSTERGAARD; L. B. N ILSSON; J. C. N ILSSON; J. P. R ASMUSSEN; P. G. B ERTHELSEN

2005-01-01

77

Model reference adaptive control of cardiac output and blood pressure through two drug infusions  

Microsoft Academic Search

Control of blood pressure and cardiac output, with dopamine and sodium nitroprusside has been achieved using a model reference adaptive controller. A procedure for selecting the adaptation weights for a 2×2 system has been developed. Satisfactory model following has occurred despite time delays that caused stability criteria to be violated. The structure of the plant prohibited zero steady state error

Elisa Hope Barney; Howard Kaufman

1990-01-01

78

Lithium dilution cardiac output measurement in oleic acid–induced pulmonary edema  

Microsoft Academic Search

Objective: To determine whether lung injury influences the accuracy of lithium dilution cardiac output (CO) measurement. Design: Animal experimental study. Setting: Animal experimental laboratory. Participants: Swine (n = 23) weighing 26.4 ± 2.47 kg (mean ± SD). Interventions: The animals were anesthetized and tracheotomized, then a pulmonary artery catheter was inserted into the right jugular vein, and a catheter (18G)

Tadayoshi Kurita; Koji Morita; Hiroyuki Kawasaki; Kiyoyasu Fujii; Tomiei Kazama; Shigehito Sato

2002-01-01

79

Circulation Time in Man from Lung to Periphery as an Indirect Index of Cardiac Output  

Microsoft Academic Search

Circulation time (Ct) between lung and periphery may be a surrogate for cardiac output, estimated here, for the most part, as the time between taking a breath of nitrogen and peripheral detection of a desaturation pulse. Use of pulse oximetry involves an internal, instrument delay; however, using the ear, we found shortening with exercise (12.1 ± 0.37 sec, at rest;

Chris B. Wolff; Sophie K. Checkley; Georgina Bhageerutty; Himanshu Bhatt; Atholl Johnston; David Collier; Ilias Tachtsidis; N. Garvie; M. Rosenberg; Nigel Benjamin

80

Comparison of electrical velocimetry and transoesophageal Doppler echocardiography for measuring stroke volume and cardiac output  

Microsoft Academic Search

Background. Impedance cardiography (ICG) has been used extensively to estimate stroke volume (SV) and cardiac output (CO) from changes of thoracic electrical bioimpedance (TEB). However, studies comparing ICG with reference methods have questioned the reliability of this approach. Electrical velocimetry (EV) provides a new algorithm to calculate CO from variations in TEB. As the transoesophageal Doppler echocardiographic quantification of CO

C. Schmidt; G. Theilmeier; H. Van Aken; P. Korsmeier; S. P. Wirtz; E. Berendes; A. Hoffmeier; A. Meissner

2005-01-01

81

Effects of vasopressin on left anterior descending coronary artery blood flow during extremely low cardiac output  

Microsoft Academic Search

Because of the possibility of vasopressin-mediated coronary vasospasm, this study was designed to assess effects of vasopressin compared to saline placebo on left anterior descending (LAD) coronary artery blood flow. Twelve anaesthetized domestic swine were prepared for LAD coronary artery blood flow measurement with ultrasonic flow probes, using cardiopulmonary by-pass adjusted to 10% of the prearrest cardiac output. This 10%

Viktoria D Mayr; Volker Wenzel; Tilko Müller; Herwig Antretter; Klaus Rheinberger; Karl H Lindner; Hans-Ulrich Strohmenger

2004-01-01

82

Continuous and intermittent cardiac output measurement: pulmonary artery catheter versus aortic transpulmonary technique  

Microsoft Academic Search

Background. Cardiac output (CO) can be measured intermittently by bolus thermodilution methods in the pulmonary artery (COpa) or in the aorta (COart). A continuous thermodilu- tion method (CCO) and a method for continuous estimation using the arterial pulse wave (PCCO) are also available. Methods. We compared two methods of intermittent CO measurements in patients during liver transplantation: COpa, regarded as

G. Della Rocca; L. Pompei; C. Cocci; P. Pietropaoli

2002-01-01

83

Investigations concerning the application of the cross-correlation method in cardiac output measurements  

PubMed Central

Background In spite of numerous non-invasive examinations the “gold clinical standard” of cardiac output measurements is the invasive pulmonary artery catheterization by means of the Swan-Ganz catheter and the application of the thermodilution method to estimate the blood flow. The results obtained by means of thermodilution are sensitive to many physical and biological disturbances. The unreliability of this method amounts to 20-45% and depends on the given variant of the method. Therefore some other method, more accurate and resistant to disturbances, was looked for. This paper presents a new approach to cardiac output measurements, based on cross-correlation signal analysis. The goal of investigations was to verify experimentally the application of the cross-correlation method of cardiac output measurements. Results In 99.2% of the examined cases the extreme of the cross-correlation function was easy to be estimated by numerical algorithms. In 0,8% of the remaining cases (with a plateau region adjacent to the maximum point) numerical detection of the extreme was inaccurate. The typical unreliability of the investigated method amounted o 5.1% (9.8% in the worst case). Investigations performed on a physical model revealed that the unreliability of cardiac output measurements by means of the cross-correlation method is 3–5 times better than in the case of thermodilution. Conclusions The performed investigations and theoretical analysis have shown, that the cross-correlation method may be applied in cardiac output measurements. This kind of measurements seems to be more accurate and disturbance-resistant than clinically applied thermodilution.

2012-01-01

84

Beat-to-beat measurement of cardiac output by intravascular pulse contour analysis: A prospective criterion standard study in patients after cardiac surgery  

Microsoft Academic Search

Objective: To evaluate the accuracy of a new pulse contour method of measuring cardiac output in critically ill patients. p ]Design: A prospective criterion standard study. p ]Setting: Cardiac surgery intensive care unit in a university hospital. p ]Participants: Nineteen cardiac surgery patients requiring intensive care treatment with pulmonary artery catheters after surgery. p ]Interventions: None. p ]Measurements and Main

Christian Zöllner; Mathias Haller; Marion Weis; Karl Mörstedt; Peter Lamm; Erich Kilger; Alwin E. Goetz

2000-01-01

85

A Meta-Analysis of Studies Using Bias and Precision Statistics to Compare Cardiac Output Measurement Techniques  

Microsoft Academic Search

Introduction. Bias and precision statistics have succeeded regression analysis when measurement techniques are compared. However, when applied to cardiac output measurements, inconsistencies occur in reporting the results of this form of analysis. Methods. A MEDLINE search was performed, dating from 1986. Studies comparing techniques of cardiac output measurement using bias and precision statistics were surveyed. An error-gram was constructed from

Lester A. H. Critchley; Julian A. J. H. Critchley

1999-01-01

86

The decrease of cardiac chamber volumes and output during positive-pressure ventilation.  

PubMed

Positive-pressure ventilation (PPV) is widely used for treatment of acute cardiorespiratory failure, occasionally at the expense of compromised cardiac function and arterial blood pressure. The explanation why has largely rested on interpretation of intracardiac pressure changes. We evaluated the effect of PPV on the central circulation by studying cardiac chamber volumes with cardiac magnetic resonance imaging (CMR). We hypothesized that PPV lowers cardiac output (CO) mainly via the Frank-Starling relationship. In 18 healthy volunteers, cardiac chamber volumes and flow in aorta and the pulmonary artery were measured by CMR during PPV levels of 0, 10, and 20 cmH2O applied via a respirator and a face mask. All cardiac chamber volumes decreased in proportion to the level of PPV. Following 20-cmH2O PPV, the total diastolic and systolic cardiac volumes (±SE) decreased from 605 (±29) ml to 446 (±29) ml (P < 0.001) and from 265 (±17) ml to 212 (±16) ml (P < 0.001). Left ventricular stroke volume decreased by 27 (±4) ml/beat; heart rate increased by 7 (±2) beats/min; and CO decreased by 1.0 (±0.4) l/min (P < 0.001). From 0 to 20 cmH2O, right and left ventricular peak filling rates decreased by -146 (±32) and -187 (±64) ml/s (P < 0.05) but maximal emptying rates were unchanged. Cardiac filling and output decrease with increasing PPV in healthy volunteers. The decrease is seen even at low levels of PPV and should be taken into account when submitting patients to mechanical ventilation with positive pressures. The decrease in CO is fully explained by the Frank-Starling mechanism. PMID:23893161

Kyhl, Kasper; Ahtarovski, Kiril Aleksov; Iversen, Kasper; Thomsen, Carsten; Vejlstrup, Niels; Engstrøm, Thomas; Madsen, Per Lav

2013-07-26

87

Arterial pressure-based cardiac output in septic patients: different accuracy of pulse contour and uncalibrated pressure waveform devices  

Microsoft Academic Search

INTRODUCTION: We compared the ability of two devices estimating cardiac output from arterial pressure-curve analysis to track the changes in cardiac output measured with transpulmonary thermodilution induced by volume expansion and norepinephrine in sepsis patients. METHODS: In 80 patients with septic circulatory failure, we administered volume expansion (40 patients) or introduced\\/increased norepinephrine (40 patients). We measured the pulse contour-derived cardiac

Xavier Monnet; Nadia Anguel; Brice Naudin; Julien Jabot; Christian Richard; Jean-Louis Teboul

2010-01-01

88

First-pass radionuclide determination of cardiac output: an improved gamma camera method  

SciTech Connect

A technique for noninvasive determination of cardiac output by aid of first-pass radionuclide cardiography is described. After intravenous injection of 10-15 mCi technetium-99m-(99mTc) labeled red blood cells the method requires acquisition of a first passage time-activity curve recorded with a gamma camera over the left ventricle, the background corrected left ventricular count rate recorded after complete mixing of the tracer in the circulation, and determination of the distribution volume of the tracer. The method was applied in 14 patients with heart disease of various origins and evaluated against the conventional tracer dilution technique with arterial sampling of blood activity. Cardiac output determinations by external counting ranged from 2.30 to 8.56 l/min, mean +/- s.d. 4.50 +/- 1.66 l/min and by arterial blood sampling from 1.88 to 8.96 l/min, mean +/- s.d. 4.52 +/- 1.71 l/min. An excellent correlation was demonstrated between the two techniques, r = 0.978 (p less than 0.001). When no background subtraction was applied to the left ventricular counts at equilibrium, radionuclide cardiac output values were approximately 40% higher than those obtained by arterial sampling. The new first-pass radionuclide cardiographic technique may prove a useful tool in the noninvasive evaluation of cardiac function, especially in patients with arrhythmias and/or valvular incompetence.

Kelbaek, H.; Hartling, O.J.; Skagen, K.; Munck, O.; Henriksen, O.; Godtfredsen, J.

1987-08-01

89

Non-invasive cardiac output trending during exercise recovery on a bathroom-scale-based ballistocardiograph.  

PubMed

Cardiac ejection of blood into the aorta generates a reaction force on the body that can be measured externally via the ballistocardiogram (BCG). In this study, a commercial bathroom scale was modified to measure the BCGs of nine healthy subjects recovering from treadmill exercise. During the recovery, Doppler echocardiogram signals were obtained simultaneously from the left ventricular outflow tract of the heart. The percentage changes in root-mean-square (RMS) power of the BCG were strongly correlated with the percentage changes in cardiac output measured by Doppler echocardiography (R(2) = 0.85, n = 275 data points). The correlation coefficients for individually analyzed data ranged from 0.79 to 0.96. Using Bland-Altman methods for assessing agreement, the mean bias was found to be -0.5% (+/-24%) in estimating the percentage changes in cardiac output. In contrast to other non-invasive methods for trending cardiac output, the unobtrusive procedure presented here uses inexpensive equipment and could be performed without the aid of a medical professional. PMID:19202234

Inan, O T; Etemadi, M; Paloma, A; Giovangrandi, L; Kovacs, G T A

2009-02-06

90

Continuous minimally invasive peri-operative monitoring of cardiac output by pulmonary capnotracking: comparison with thermodilution and transesophageal echocardiography.  

PubMed

A number of technologies are available for minimally-invasive cardiac output measurement in patients during surgery but remain little used. A system has been developed based on CO(2) elimination (VCO(2)) by the lungs for use in ventilated patients, which can be fully integrated into a modern anesthesia/monitoring platform, and provides semi-automated, continuous breath-by-breath cardiac output monitoring. A prototype measurement system was constructed to measure VCO(2) and end-tidal CO(2) concentration with each breath. A baseline measurement of non-shunt cardiac output was made during a brief change in ventilator rate, according to the differential CO(2) Fick approach. Continuous breath-by-breath monitoring of cardiac output was then performed from measurement of VCO(2), using a derivation of the Fick equation applied to pulmonary CO(2) elimination. Automated recalibration was done periodically and data was processed and cardiac output displayed in real time. Measurements were compared with simultaneous measurements by bolus thermodilution in 77 patients undergoing cardiac surgery or liver transplantation. Overall mean bias [sd] for agreement in cardiac output measurement was -0.1 [1.2] L/min, percentage error +44.2%, r = 0.92. Concordance in measurement of changes of at least 15% in cardiac output was 80%. The method followed sudden changes in cardiac output due to arrythmias and run onto cardiopulmonary bypass in real time. The accuracy and precision were comparable to other clinical techniques. The method is relatively seamless and largely automated and has potential for continuous, cardiac output monitoring in ventilated patients during anesthesia and critical care. PMID:22350312

Peyton, Philip J

2012-02-18

91

Changes in cardiac output during swimming and aquatic hypoxia in the air-breathing Pacific tarpon.  

PubMed

Pacific tarpon (Megalops cyprinoides) use a modified gas bladder as an air-breathing organ (ABO). We examined changes in cardiac output (V(b)) associated with increases in air-breathing that accompany exercise and aquatic hypoxia. Juvenile (0.49 kg) and adult (1.21 kg) tarpon were allowed to recover in a swim flume at 27 degrees C after being instrumented with a Doppler flow probe around the ventral aorta to monitor V(b) and with a fibre-optic oxygen sensor in the ABO to monitor air-breathing frequency. Under normoxic conditions and in both juveniles and adults, routine air-breathing frequency was 0.03 breaths min(-1) and V(b) was about 15 mL min(-1) kg(-1). Normoxic exercise (swimming at about 1.1 body lengths s(-1)) increased air-breathing frequency by 8-fold in both groups (reaching 0.23 breaths min(-1)) and increased V(b) by 3-fold for juveniles and 2-fold for adults. Hypoxic exposure (2 kPa O2) at rest increased air-breathing frequency 19-fold (to around 0.53 breaths min(-1)) in both groups, and while V(b) again increased 3-fold in resting juvenile fish, V(b) was unchanged in resting adult fish. Exercise in hypoxia increased air-breathing frequency 35-fold (to 0.95 breaths min(-1)) in comparison with resting normoxic fish. While juvenile fish increased V(b) nearly 2-fold with exercise in hypoxia, adult fish maintained the same V(b) irrespective of exercise state and became agitated in comparison. These results imply that air-breathing during exercise and hypoxia can benefit oxygen delivery, but to differing degrees in juvenile and adult tarpon. We discuss this difference in the context of myocardial oxygen supply. PMID:17869150

Clark, T D; Seymour, R S; Christian, K; Wells, R M G; Baldwin, J; Farrell, A P

2007-08-01

92

Dynamic asymmetries of cardiac output transients in response to muscular exercise in man.  

PubMed Central

1. We determined the kinetics of cardiac output (Q) with respect to oxygen uptake (VO2) at the on- and off-transients of constant-load exercise. Six subjects performed constant-load exercise which consisted of 5 min rest, 5 min one-legged pedalling at 50 W and a 5 min recovery period. 2. The transient responses were characterized by first-order kinetics. There was no significant difference between the time constants for VO2 (tau VO2) at the on- (33.9 +/- 3.5 s, mean +/- S.E.M.) and off-transient (37.2 +/- 2.9 s). The time constant for Q (tau Q, 29.4 +/- 3.2 s) was consistently shorter than tau VO2 at the on-transient. However, tau Q was appreciably longer at the off-transient (44.3 +/- 3.6 s) than the on-transient. 3. The results support the contention that the time constant for the on-transient of Q is appreciably faster than that for VO2 and hence there seems little justification for the notion that the time constants for the kinetics of VO2 are determined by the limitations of blood flow in the transient. The asymmetry of Q kinetics, with the off-transient tau Q being appreciably slower than the on-transient tau Q, serves to maintain a sufficiently high oxygen flow to the muscle during recovery from exercise at a time when the muscle oxygen uptake remains high.

Yoshida, T; Whipp, B J

1994-01-01

93

Enhanced cardiac thermal dilution analysis for cardiac output, volumes, stroke volumes, and regurgitation rates--sensitivity analysis using digital simulation.  

PubMed

Cardiac output is measured by placing a double lumen catheter with a thermistor on the tip through the right ventricle into the pulmonary artery, injecting cold saline into the right atrium, and integrating the resulting pulmonary artery temperature profile. If a similar procedure is performed with thermistors located in the right atrium, right ventricle, and pulmonary artery, the resulting temperature curves are determined by the known or easily measured quantities: injectate temperature, injectate volume, heart rate, systolic time interval, body temperature, and time in the cardiac cycle at which injection begins and the unknown quantities: right atrial, right ventricular, pulmonary artery mean and stroke volumes, inflow and outflow valve regurgitation rates, and cardiac output. A digital computer program using a lumped parameter model has been developed to use these quantities to produce thermal dilution curves and optimize the fit of the model curves to the temperature curves from the thermal dilution measurement to determine the unknown quantities. The program is used to investigate the effects of measuring system time constant, heat transfer, and noise on the accuracy of these measurements. The results indicate that the method is practical. PMID:10999367

Donovan, F M; Taylor, B C

2000-01-01

94

Continuous and intermittent cardiac output measurement in hyperdynamic conditions: pulmonary artery catheter vs. lithium dilution technique  

Microsoft Academic Search

Objective  This study aimed to assess the level of agreement of both intermittent cardiac output monitoring by the lithium dilution technique\\u000a (COLi) and continuous cardiac output monitoring (PulseCOLi) using the arterial pressure waveform with intermittent thermodilution using a pulmonary artery catheter (COPAC).\\u000a \\u000a \\u000a \\u000a Design  Prospective, single-center evaluation.\\u000a \\u000a \\u000a \\u000a Setting  University Hospital Intensive Care Unit.\\u000a \\u000a \\u000a \\u000a Patients  Patients (n?=?23) receiving liver transplantation.\\u000a \\u000a \\u000a \\u000a Intervention  Pulmonary artery catheters were placed in all

Maria Gabriella Costa; Giorgio Della Rocca; Paolo Chiarandini; Silvia Mattelig; Livia Pompei; Mauricio Sainz Barriga; Toby Reynolds; Maurizio Cecconi; Paolo Pietropaoli

2008-01-01

95

In vitro approach to study the influence of the cardiac output distribution on drug concentration  

Microsoft Academic Search

Summary  Blood flow is not constant during the day, not only due to cardiac output variation but to the variable blood flow fraction\\u000a supplied to the organs. To what extent these variations could affect the relative drug concentration between two different\\u000a tissues, is the purpose of this work. In order to study that, a device was designed which took into account

P. Fagiolino; F. Wilson; E. Samaniego; M. Vázquez

2003-01-01

96

Changes in cardiac output during swimming and aquatic hypoxia in the air-breathing Pacific tarpon  

Microsoft Academic Search

Pacific tarpon (Megalops cyprinoides) use a modified gas bladder as an air-breathing organ (ABO). We examined changes in cardiac output (V?b) associated with increases in air-breathing that accompany exercise and aquatic hypoxia. Juvenile (0.49 kg) and adult (1.21 kg) tarpon were allowed to recover in a swim flume at 27 °C after being instrumented with a Doppler flow probe around the ventral aorta

T. D. Clark; R. S. Seymour; K. Christian; R. M. G. Wells; J. Baldwin; A. P. Farrell

2007-01-01

97

Comparison of pulmonary artery and arterial thermodilution cardiac output in critically ill patients  

Microsoft Academic Search

Objective: We studied the agreement between cardiac output measurements via pulmonary artery thermodilution [CO(PA)], regarded as the\\u000a current clinical gold standard, and aortic transpulmonary thermodilution [CO(AORTA)]. Design: Prospective clinical study. Setting: Surgical intensive care unit of a university hospital. Patients: 37 patients with sepsis or septic shock (n = 34) and subarachnoid haemorrhage (n = 3). Measurements and results: We

S. G. Sakka; K. Reinhart; A. Meier-Hellmann

1999-01-01

98

Temporal stability of ambulatory stroke volume and cardiac output measured by impedance cardiography  

Microsoft Academic Search

Recently, devices have become available that allow non-invasive measurement of stroke volume and cardiac output through ambulatory thorax impedance recording. If such recordings have adequate temporal stability, they offer great potential to further our understanding of how repeated or chronic cardiovascular activation in response to naturalistic events may contribute to cardiovascular disease. In this study, 24h ambulatory impedance-derived systolic time

Annebet D. Goedhart; Nina Kupper; Gonneke Willemsen; Dorret I. Boomsma; Eco J. C. de Geus

2006-01-01

99

Flow velocity profile of the pulmonary artery measured by the continuous cardiac output monitoring catheter  

Microsoft Academic Search

The KATS catheter (continuous arterial thermodeprivation system catheter) measures the blood flow velocity of the pulmonary\\u000a artery (PA) by thermodeprivation which enables continuous determination of cardiac output. The accuracy of this system may\\u000a depend on the degree of uniformity of flow velocity in the PA, because small movements of the catheter within the PA are inevitable\\u000a with a beating heart.

Keiko Miyasaka; Masao Takata; Katsuyuki Miyasaka MO

1993-01-01

100

Transpulmonary thermodilution cardiac output measurement using the axillary artery in critically ill patients  

Microsoft Academic Search

Study Objective: To compare cardiac output (CO) as measured by the arterial thermodilution technique using only a central venous catheter and an arterial catheter inserted into the axillary artery, with conventional CO measurement with thermodilution using a pulmonary artery (PA) catheter (PAC).Design: Prospective clinical study in which each patient served as his\\/her own control.Setting: General ICU of a large tertiary-care

Eran Segal; Rita Katzenelson; Haim Berkenstadt; Azriel Perel

2002-01-01

101

Measurement of cardiac output by transesophageal echocardiography in mechanically ventilated patients  

Microsoft Academic Search

Objective: The determination of basal cardiac output (CO) and of its variations during different therapeutic interventions liable to\\u000a increase or decrease it in mechanically ventilated patients using transesophageal echocardiography (TEE). Design: To compare CO measurements simultaneously obtained by transmitral single-plane TEE and thermodilution. Setting: Medical intensive care unit. Patients: Twenty-two consecutive mechanically ventilated patients hospitalized for various medical conditions were

P. Estagnasié; K. Djedaini; L. Mier; F. Coste; D. Dreyfuss

1997-01-01

102

Multiple-model adaptive predictive control of mean arterial pressure and cardiac output  

Microsoft Academic Search

A multiple-model adaptive predictive controller has been designed to simultaneously regulate mean arterial pressure and cardiac output in congestive heart failure subjects by adjusting the infusion rates of nitroprusside and dopamine. The algorithm is based on the multiple-model adaptive controller and utilizes model predictive controllers to provide reliable control in each model subspace. A total of 36 linear small-signal models

Clement Yu; Rob J. Roy; Howard Kaufman; B. Wayne Bequette

1992-01-01

103

Reliability of peak and maximal cardiac output assessed using thoracic bioimpedance in children  

Microsoft Academic Search

The purpose of this study was to evaluate the reliability of a thoracic electrical bioimpedance based device (PhysioFlow) for the determination of cardiac output and stroke volume during exercise at peak oxygen uptake (peak \\u000a in children. The reliability of peak \\u000a is also reported. Eleven boys and nine girls aged 10–11 years completed a cycle ergometer test to voluntary exhaustion on three

Joanne Welsman; Katie Bywater; Colin Farr; Deborah Welford; Neil Armstrong

2005-01-01

104

Pressure Pulse Contour-derived Stroke Volume and Cardiac Output in the Morbidly Obese Patient  

Microsoft Academic Search

Background  The pressure pulse contour method for measuring stroke volume (SV) and cardiac output (CO) has come of age. Various methods\\u000a have been proposed, but at this time no single technique has shown clear superiority over the others. This commentary and\\u000a review discusses the various methods, and particularly the pressure recording analytical method (PRAM). Dissection of the\\u000a method shows that vascular

Donald P. Bernstein

2008-01-01

105

Measurement of cardiac output using near-infrared heating of blood  

NASA Astrophysics Data System (ADS)

Thermodilution-based cardiac output measurements are made using iced saline or blood heated by resistive heating as a dilutable indicator. Because near-infrared irradiation penetrates sufficiently deeply into blood, it can safely deposit up to six times the energy of a resistive heater, improving the accuracy of the measurements while continuously monitoring cardiac output. We have developed a prototype system using 980 nm diode lasers to irradiate blood through a diffuser. This system was tested using an optical blood phantom and was compared to iced-saline injection and resistive heating. Three flow estimates were made at each of 18 combinations of stroke rate, stroke volume, and systole/diastole ratios. Accuracy was determined by the quality of the fit between the estimated flows and the actual flow. Reproducibility was determined by the normalized standard deviation. Results: Measurements made by saline injection were the most accurate (R2 equals 0.982) and reproducible (NSD equals 2.8%). Power limitations on the resistive heating to ensure a safe blood temperature limited its accuracy (R2 equals 0.537) and reproducibility (NSD equals 18.1%). Laser-based heating showed reasonable accuracy and reproducibility (R2 equals 0.950, NSD equals 7.8%). Laser heating thus represents a potentially more accurate alternative to saline injection for cardiac output measurement than does resistive heating.

Curley, Michael G.; Hamilton, Patrick S.; Walsh, Joseph T.

1997-05-01

106

Delayed time response of the continuous cardiac output pulmonary artery catheter.  

PubMed

Previous studies of the accuracy of pulmonary artery catheters (PAC) which provide continuous cardiac output (CCO) monitoring have investigated the performance during steady-state conditions. We compared the response time to hemodynamic change using a CCO PAC and an ultrasonic flow probe (UFP). In five sheep, a CCO PAC was inserted, and an UFP for measurement of CCO was placed around the pulmonary artery via a left thoracotomy. Six interventions which rapidly alter cardiac output were studied: crystalloid bolus, balloon inflation in the inferior vena cava (IVC), IVC balloon deflation, dobutamine infusion, hemorrhage, and reinfusion of blood. Cardiac output measured before and after each intervention was used to calculate the total change caused by the intervention, and the time intervals from intervention to 20%, 50%, and 80% of that change were noted. For all interventions, the time response of CCO was significantly slower than UFP. The largest differences were seen with the rapid infusion of lactated Ringer's solution for which the time interval for 20% change was 7.3 +/- 2.3 min (mean +/- SD) for CCO versus 0.5 +/- 0.3 min for UFP. The time interval for 80% change was 14.5 +/- 4.1 min for CCO versus 1.8 +/- 0.9 min with UFP. The current study demonstrates clinically important time delays in the response of the CCO catheter. This delay must be considered when rapid alterations of the hemodynamic state may occur. PMID:8942581

Siegel, L C; Hennessy, M M; Pearl, R G

1996-12-01

107

Alpha-adrenergic regulation of splanchnic volume and cardiac output in the dog.  

PubMed

The present study examined whether alpha-adrenergic stimulation causes a change in splanchnic intravascular volume in the anaesthetized animal with an intact circulation, which region(s) mediate the volume change, and whether the splanchnic volume change influences cardiac output. In order to ascertain that a radionuclide imaging technique could be used to assess total splanchnic volume changes, drugs known to increase or decrease splanchnic volume were infused on 21 occasions in eight dogs studied under conditions of selective perfusion and drainage of the splanchnic vasculature with erythrocytes labelled with 99Tcm and a gamma camera placed over the abdomen. For these 21 infusions, volume and radionuclide count changes were related: r greater than or equal to 0.90 (n = 20), r = 0.76 (n = 1). After ascertaining tissue attenuation and blood radioactivity in four of the animals, the standard error for a single estimate of the absolute volume change using the radionuclide technique was determined to be 75 ml. In six animals with intact circulations, phenylephrine (40-80 micrograms min-1) for 20 min was associated with an increase in cardiac output of 12 +/- 2% (P less than 0.001) and a decrease in total splanchnic volume estimated to be 431 +/- 95 ml (P less than 0.001). The splanchnic volume decrease was due entirely to decreases in splenic and intestinal volume. In eight eviscerated animals, cardiac output decreased by 30 +/- 2% (P less than 0.001) during phenylephrine.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2158209

Bell, L; Hennecken, J; Zaret, B L; Rutlen, D L

1990-03-01

108

Cardiac output variations in supine resting subjects during head-out cold water immersion  

NASA Astrophysics Data System (ADS)

Five men, aged 31.2 years (SD 2.3), under semi-nude conditions and resting in a dorsal reclining position, were exposed to thermoneutral air for 30 min, followed immediately by a cold water (15°C) immersion for 60 min. Cardiac output was measured using a dualbeam Doppler flow meter. During immersion in cold water, cardiac frequency ( f c) showed an initial bradycardia. The lowest values were reached at about 10 min after immersion, 58.3 (SD 2.5) to 48.3 (SD 7.8) beats min-1 ( P < 0.05). By the 20th min of exposure, f c had gradually risen to 70.0 beats min-1 (SD 6.6, P < 0.05). This change could be due to the inhibition of the initial vagal reflex by increased catecholamine concentration. Stroke volume ( V s) was significantly increased ( P < 0.05) during the whole cold immersion period. Cardiac output, increased from 3.57 (SD 0.50) to 6.26 (SD 1.33)1 min-1 ( P < 0.05) and its change with time was a function of both V s and f c. On the other hand, systolic flow acceleration was unchanged during the period of immersion. The changes in the respiratory variables (ventilation, oxygen uptake, carbon dioxide output and respiratory exchange ratio) during immersion showed an initial hyperventilation followed, as immersion proceeded, by a slower metabolic increase due to shivering.

Vogelaere, P.; Deklunder, G.; Lecroart, J.

1995-03-01

109

Cardiac Remodeling in Fish: Strategies to Maintain Heart Function during Temperature Change  

PubMed Central

Rainbow trout remain active in waters that seasonally change between 4°C and 20°C. To explore how these fish are able to maintain cardiac function over this temperature range we characterized changes in cardiac morphology, contractile function, and the expression of contractile proteins in trout following acclimation to 4°C (cold), 12°C (control), and 17°C (warm). The relative ventricular mass (RVM) of the cold acclimated male fish was significantly greater than that of males in the control group. In addition, the compact myocardium of the cold acclimated male hearts was thinner compared to controls while the amount of spongy myocardium was found to have increased. Cold acclimation also caused an increase in connective tissue content, as well as muscle bundle area in the spongy myocardium of the male fish. Conversely, warm acclimation of male fish caused an increase in the thickness of the compact myocardium and a decrease in the amount of spongy myocardium. There was also a decrease in connective tissue content in both myocardial layers. In contrast, there was no change in the RVM or connective tissue content in the hearts of female trout with warm or cold acclimation. Cold acclimation also caused a 50% increase in the maximal rate of cardiac AM Mg2+-ATPase but did not influence the Ca2+ sensitivity of this enzyme. To identify a mechanism for this change we utilized two-dimensional difference gel electrophoresis to characterize changes in the cardiac contractile proteins. Cold acclimation caused subtle changes in the phosphorylation state of the slow skeletal isoform of troponin T found in the heart, as well as of myosin binding protein C. These results demonstrate that acclimation of trout to warm and cold temperatures has opposing effects on cardiac morphology and tissue composition and that this results in distinct warm and cold cardiac phenotypes.

Klaiman, Jordan M.; Fenna, Andrew J.; Shiels, Holly A.; Macri, Joseph; Gillis, Todd E.

2011-01-01

110

Ultrasound Dilution: An Accurate Means of Determining Cardiac Output in Children  

PubMed Central

Background Cardiac output (CO) is a useful measure of myocardial performance. CO monitoring is frequently performed in critically ill adults in order to guide physicians’ treatment strategies. However, standard methods of determining CO in children are not without risk and can be problematic secondary to their invasive nature and other technical problems. COstatus® system (Transonic Systems Inc, NY, USA), which is based on ultrasound dilution technology, works off in situ catheters and uses an innocuous indicator to allow for routine measurements of cardiac output and blood volumes in pediatric patients. The purpose of this study was to validate CO measured by COstatus® with those obtained by the clinical standard technique of pulmonary artery (PAC) thermodilution. Methods This was a prospective evaluation performed at a single institution. Any child with a structurally normal heart undergoing hemodynamic evaluation in the cardiac catheterization laboratory was included. A prograde right heart catheterization was performed, and CO was first determined by using the PAC thermodilution technique. Thermodilution results were then compared with CO measurements obtained using the COstatus system. The results were analyzed by standard correlation, Bland-Altman, and Crichtley and Critchley analyses. Results Twenty-eight patients were evaluated with a median age of 8 yrs and a median weight of 31 kg. The mean thermodilution cardiac index = 3.18 L/min (+/? 1.35 L/min), and the mean COstatus® cardiac index = 3.17 L/min (+/? 1.31 L/min). Standard Pearson correlation tests revealed an excellent correlation coefficient of 0.95 (p<0.0001). Bland-Altman analysis revealed good clinical agreement with a mean difference of ?0.004 L/min with a precision of 0.8 L/min/ at 2 SD. A percentage error of 25.4% was noticed in this study which is less than the clinically acceptable limit. Conclusion The ultrasound dilution technique of determining CO using the COstatus® system provides a less invasive method than the traditional pulmonary artery thermodilution for accurately determining cardiac output in children. This is the first validation of the COstatus® system in pediatric patients. Further studies are required to establish its accuracy in pediatric patients with cardiac shunts and other hemodynamically unstable conditions.

Crittendon, Ivory; Dreyer, William J.; Decker, Jamie A; Kim, Jeffrey J.

2011-01-01

111

The influence of nonlinear intra-thoracic vascular behaviour and compression characteristics on cardiac output during CPR.  

PubMed

Clinical observations suggest that the assumption of a linear relationship between chest compression pressure and cardiac output may be oversimplified. More complex behaviour may occur when the transmural pressure is large, changing the compliances and resistances in the intra-thoracic vasculature. A fundamental understanding of these compression induced phenomena is required for improving CPR. An extensively used, lumped element computer model (model I) of the circulation was upgraded and refined to include the intrathoracic vasculature (model II). After validation, model II was extended by adding variable compliances and resistances (model III) to the vascular structures. Successively, ranges of compression pressures, frequencies, duty cycles and compression pulse shapes were applied while controlling all other parameters. Cardiac output was then compared. The nonlinearities in compliance and resistance become important, limiting factors in cardiac output, starting in our experimental series at 70 mmHg peak compression pressure, and increasing with higher pressures. This effect is reproducible for sinusoidal and trapezoidal compression forms, resulting in lower cardiac output in all experiments at high compression pressures. Duty cycle and wait time are key parameters for cardiac output. Our data strongly indicate that vascular compliance, especially the ability of vessels to collapse (and potentially the cardiac chambers), can be a central factor in the limited output generated by chest compressions. Just pushing 'harder' or 'faster' is not always better, as an 'optimal' force and frequency may exist. Overly forceful compression can limit blood flow by restricting filling or depleting volume in the cardiac chambers and central great vessels. PMID:21324578

Koeken, Yvette; Aelen, Paul; Noordergraaf, Gerrit J; Paulussen, Igor; Woerlee, Pierre; Noordergraaf, Abraham

2011-02-15

112

Evaluation of impedance cardiography as a non-invasive means of measuring systolic time intervals and cardiac output.  

PubMed

Impedance cardiography was used for non-invasive determinations of systolic time intervals (STI) and cardiac output. The results were compared with simultaneously obtained invasive measurements of STI from central aortic pressure curves and of cardiac output using the dye-dilution technique. The study was performed on eight dogs during increasing halothane concentration. A close correlation was found between non-invasively and invasively measured left ventricular ejection time = LVET (r = 0.986) and pre-ejection period - PEP (r - 0.948). Measurements of cardiac output derived from changes in thoracic impedance were determined 1) using a fixed value of p (p - the resistivity of blood) and 2) using an individual value of p based on the actual hematocrits. When compared to cardiac outputs obtained by dye-dilution the correlation coefficients were r = 0.806 and r = 0.816, respectively. Impedance cardiography is a useful method of evaluating changes in cardiac output. The method permits simultaneous observations of changes in STI and cardiac output as an index of cardiac function. PMID:1101602

Rasmussen, J P; Sorensen, B; Kann, T

1975-01-01

113

Mathematical basis for the measurement of absolute and fractional cardiac output with diffusible tracers by compartmental analysis methods  

SciTech Connect

Using compartmental analysis methods, a mathematical basis is given for the measurement of absolute and fractional cardiac output with diffusible tracers. Cardiac output is shown to be the product of the blood volume and the sum of the rate constants of tracer egress from blood, modified by a factor reflecting transcapillary diffusibility, the transfer fraction. The return of tracer to the blood and distant (intracellular) events are shown to play no role in the solution. Fractional cardiac output is the ratio of the rate constant of tracer egress from blood to an organ, divided by the sum of the egress constants from blood. Predominantly extracellular ions such as sodium or bromide are best suited for this technique, although theoretically any diffusible tracer whose compartmental model can be solved may be used. It is shown that fractional cardiac output is independent of the transfer fraction, and therefore can be measured accurately by tracers which are not freely diffusible.

Charkes, N.D.

1984-10-01

114

Reliability of Cardiac Output Calculation by the Fick Principle and Central Venous Oxygen Saturation in Emergency Conditions  

Microsoft Academic Search

Background  For many years thermodilution has been the gold standard for determining cardiac output in the critically ill patients. Less\\u000a invasive methods have recently been introduced. This study aimed at evaluating the agreement between cardiac output (CO) measured\\u000a by a new Fick method, using central venous saturation (Scvo2), and that measured by the classic thermodilution technique, in patients requiring emergent CO

Avi A. Weinbroum; Philippe Biderman; Dror Soffer; Joseph M. Klausner; Oded Szold

2008-01-01

115

Accuracy of an indirect carbon dioxide Fick method in determination of the cardiac output in critically ill mechanically ventilated patients  

Microsoft Academic Search

We evaluated the accuracy of an indirect CO2 Fick method for measuring cardiac output in 30 critically ill mechanically ventilated patients. When the Fick principle was applied to CO2 using estimated PaCO2, the cardiac output obtained underestimated the thermodilution technique showing a lack of accuracy. However, there was a significant correlation between thermodilution and CO2 rebreathing methods using measured (r=0.92;

L. Blanch; R. Fernfindez; S. Benito; J. Mancebo; N. Calaf; A. Net

1988-01-01

116

Evaluation of cerebral electrical activity and cardiac output after patent ductus arteriosus ligation in preterm infants.  

PubMed

Objective:To characterize and investigate the relationship between systemic blood flow and pre- and postoperative cerebral electrical activity in preterm neonates undergoing patent ductus arteriosus (PDA) ligation.Study design:A prospective observational study was conducted in 17 preterm neonates undergoing PDA ligation. All infants had amplitude-integrated electroencephalography (aEEG) recorded continuously from 4?h preoperatively to 24?h postoperatively. Targeted neonatal echocardiography was performed to evaluate myocardial performance and systemic blood flow at four sequential time points: preoperatively; 1, 8 and 24?h postoperatively.Result:PDA ligation was followed by a fall in the lower border of the aEEG trace lower left ventricular output, but recovery of diastolic flow in the middle cerebral artery. Altered lower margin was associated with gestational age and PDA diameter on univariate analysis, but not with low cardiac output.Conclusion:PDA ligation was associated with altered cerebral electrical activity, although these changes were not related to low cardiac output state. PMID:23887196

Leslie, A T F S; Jain, A; El-Khuffash, A; Keyzers, M; Rogerson, S; McNamara, P J

2013-07-25

117

Serum cortisol concentration with exploratory cut-off values do not predict the effects of hydrocortisone administration in children with low cardiac output after cardiac surgery  

PubMed Central

OBJECTIVES Low cardiac output syndrome is common after paediatric cardiac surgery. Previous studies suggested that hydrocortisone administration may improve haemodynamic stability in case of resistant low cardiac output syndrome in critically ill children. This study was set up to test the hypothesis that the effects of hydrocortisone on haemodynamics in children with low cardiac output syndrome depend on the presence of (relative) adrenal insufficiency. METHODS A retrospective study was done on paediatric patients who received hydrocortisone when diagnosed with resistant low cardiac output syndrome after paediatric cardiac surgery in the period from 1 November 2005 to 31 December 2008. We studied the difference in effects of treatment with hydrocortisone administration between patients with adrenal insufficiency defined as an exploratory cut-off value of total cortisol of <100 nmol/l and patients with a serum total cortisol of ?100 nmol/l. RESULTS A total of 62 of patients were enrolled, meeting the inclusion criteria for low cardiac output syndrome. Thirty-two patients were assigned to Group 1 (<100 nmol/l) and 30 were assigned to Group 2 (?100 nmol/l). Haemodynamics improved after hydrocortisone administration, with an increase in blood pressure, a decrease in administered vasopressors and inotropic drugs, an increase in urine production and a decrease in plasma lactate concentrations. CONCLUSIONS The effects of treatment with hydrocortisone in children with low cardiac output after cardiac surgery was similar in patients with a low baseline serum cortisol concentration and those with normal baseline cortisol levels. A cortisol value using an exploratory cut-off value of 100 nmol/l for adrenal insufficiency should not be used as a criterion to treat these patients with hydrocortisone.

Verweij, E.J.; Hogenbirk, Karin; Roest, Arno A.W.; van Brempt, Ronald; Hazekamp, Mark G.; de Jonge, Evert

2012-01-01

118

Physiologic and Clinical Principles behind Noninvasive Resuscitation Techniques and Cardiac Output Monitoring.  

PubMed

Clinical assessment and vital signs are poor predictors of the overall hemodynamic state. Optimal measurement of the response to fluid resuscitation and hemodynamics has previously required invasive measurement with radial and pulmonary artery catheterization. Newer noninvasive resuscitation technology offers the hope of more accurately and safely monitoring a broader range of critically ill patients while using fewer resources. Fluid responsiveness, the cardiac response to volume loading, represents a dynamic method of improving upon the assessment of preload when compared to static measures like central venous pressure. Multiple new hemodynamic monitors now exist that can noninvasively report cardiac output and oxygen delivery in a continuous manner. Proper assessment of the potential future role of these techniques in resuscitation requires understanding the underlying physiologic and clinical principles, reviewing the most recent literature examining their clinical validity, and evaluating their respective advantages and limitations. PMID:21860802

Napoli, Anthony M

2011-08-16

119

A pilot assessment of the FloTrac TM cardiac output monitoring system  

Microsoft Academic Search

Objective  To compare measurement of cardiac output (CO) by means of the FloTracTM CO monitor with the pulmonary artery catheter (PAC).\\u000a \\u000a \\u000a \\u000a Design  Prospective observational study.\\u000a \\u000a \\u000a \\u000a Setting  Intensive care unit of a tertiary hospital.\\u000a \\u000a \\u000a \\u000a Patients  Six post-operative cardiac surgery patients with existing arterial cannulas and PACs.\\u000a \\u000a \\u000a \\u000a Interventions  Attachment of the FloTracTM CO monitor and transducer to an existing arterial cannula. Simultaneous measurements of CO, indexed to body

Helen Ingrid Opdam; Li Wan; Rinaldo Bellomo

2007-01-01

120

[High output heart failure due to an iatrogenic arteriovenous fistula after cardiac catheterization].  

PubMed

The occurrence of an arteriovenous fistula is a potential complication of cardiac catheterization. Most of these fistulas cause no harm. We report the clinical case of a 70 years old woman with high-output heart failure caused by an arteriovenous fistula (FAV) in the groin. The fistula was successfully closed by surgical repair and the heart failure was resolved. This case confirms the potential harmfulness for the vascular bed of certain surgical/endovascular interventions and intravascular monitoring techniques. When heart failure of uncertain etiology appears in patients previously submitted to one of the above mentioned procedures, a careful clinical examination can lead to a correct diagnosis of iatrogenic FAV, whose surgical correction is usually followed by the restoration of a normal cardiac function. PMID:20140291

Ministro, Augusto; Costa, Tiago; Cunha e Sá, Diogo; Evangelista, Ana; da Gama, A Dinis

121

Accuracy of a Novel Approach to Measuring Arterial Thermodilution Cardiac Output During Intra-Aortic Counterpulsation  

Microsoft Academic Search

Objective  To assess the agreement between a novel approach of arterial and the pulmonary artery bolus thermodilution for measuring cardiac\\u000a output in critically ill patients during aortic counterpulsation.\\u000a \\u000a \\u000a \\u000a Methods  Eighteen male patients aged 37–80 years, undergoing preoperative insertion of an intra-aortic balloon pump (IABP) and elective\\u000a coronary artery bypass grafting. A thin 1.3FG thermistor was introduced through the pressure lumen to the tip

Werner Baulig; Philipp Schuett; Oliver Goedje; Edith R. Schmid

2007-01-01

122

Comparison of cardiac output measurements in critically ill patients: FloTrac/Vigileo vs transthoracic Doppler echocardiography.  

PubMed

Measurement of cardiac output is an integral part of patient management in the intensive care unit. FloTrac/Vigileo is a continuous cardiac output monitoring device that does not need re-calibration. However its reliability has been questioned in some studies, especially involving surgical patients. In this study, we evaluated the comparability of FloTrac/Vigileo and transthoracic Doppler echocardiography in 53 critically ill patients requiring continuous cardiac output monitoring. Most of these patients had septic or cardiogenic shock. Cardiac output was measured by both FloTrac/Vigileo and transthoracic Doppler echocardiography. The bias and precision (mean and SD) between the two devices was 0.35 +/- 1.35 l/minute. The limits of agreement were -2.3 to 3.0 l/minute (%error = 49.3%). When patients with irregular heart rhythms and aortic stenosis were excluded, the bias and precision was 0.02 +/- 0.80 l/minute (n = 42). The limits of agreement were -1.55 to 1.59 l/minute (%error = 29.5%). Patient demographics (body surface area, gender and age) did not affect the bias, but there was a mild tendency for FloTrac/ Vigileo to register a higher cardiac output at high heart rates. Changes in cardiac output for two consecutive days correlated well between the two methods (r = 0.86; P < 0.001). In summary, with the exceptions of patients with irregular heart rhythms and significant aortic stenosis, FloTrac/Vigileo is clinically comparable to transthoracic Doppler echocardiography in cardiac output measurements in critically ill patients. PMID:21823375

McLean, A S; Huang, S J; Kot, M; Rajamani, A; Hoyling, L

2011-07-01

123

A rebreathing method for measuring lung volume, diffusing capacity and cardiac output in conscious small animals.  

PubMed

We developed a multiple gas rebreathing technique for measuring lung diffusing capacity (DL(CO)), lung volume (V(L)) and cardiac output simultaneously in conscious spontaneously breathing small animals. Lung volume was measured from the dilution of methane (CH4) or sulfur hexafluoride (SF6) and verified independently by a helium washout technique. Cardiac output and DL(CO) were estimated from the uptake of acetylene and carbon monoxide, respectively. We tested guinea pigs at two levels of alveolar oxygen tension in order to estimate membrane diffusing capacity and pulmonary capillary blood volume by the Roughton-Forster technique. Results show that measured DL(CO) are consistent with reported values in anesthetized guinea pigs as well as with allometric comparison across species. Lung volume estimated from SF6 dilution agreed closely with that estimated independently from helium washout; however, lung volume estimated from CH4 dilution was systematically lower due to the addition of endogenously produced CH4 to the rebreathing system. We conclude that this technique can be used to measure resting lung function in conscious unsedated small animals. PMID:15766909

Yilmaz, Cuneyt; Johnson, Robert L; Hsia, Connie C W

2005-04-15

124

Correlation between supra-sternal Doppler cardiac output (USCOM) measurements and chest radiological features.  

PubMed

Cardiac output can be measured non-invasively using supra-sternal Doppler (USCOM, Sydney, NSW, Australia). However, scanning can be difficult in practice in older patients, the reason for which has not been elucidated previously. Chest radiographs from 60 previously studied anaesthetised patients were reviewed and scored for aortic unfolding, enlargement and calcification, and cardiac enlargement. Corresponding supra-sternal Doppler scans were graded as easy or difficult using the Cattermole scoring system. Twenty patients who were difficult to scan, aged 60-88 years, had mean (SD) radiological scores of 5.9 (2.5) out of 12, while 20 adult controls, 40-60 years, and 20 older patients who were easy to scan, 60-80 years, had radiological scores of 0.9 (1.1) and 1.7 (1.4), respectively (p < 0.001). Over 75% of the patients who were difficult to scan had two or more radiological features suggestive of aortic unfolding and cardiac enlargement. Morphological or anatomical changes associated with ageing within the upper chest play an important part in the success of using supra-sternal Doppler in older patients. PMID:24128014

Huang, L; Critchley, L A H; Lok, R L K; Liu, Y

2013-09-23

125

Clinical evaluation of the flotrac/vigileo(TM) system for continuous cardiac output monitoring in patients undergoing regional anesthesia for elective cesarean section: a pilot study  

PubMed Central

BACKGROUND: Spinal anesthesia for cesarean delivery may cause severe maternal hypotension and a decrease in cardiac output. Compared to assessment of cardiac output via a pulmonary artery catheter, the FloTrac/Vigileo™ system may offer a less invasive technique. The aim of this study was to evaluate cardiac output and other hemodynamic measurements made using the FloTrac/Vigileo™ system in patients undergoing spinal anesthesia for elective cesarean section. METHODS: A prospective study enrolling 10 healthy pregnant women was performed. Hemodynamic parameters were continuously obtained at 15 main points: admission to surgery (two baseline measurements), after preload, after spinal anesthesia administration and 4 time points thereafter (4, 6, 8 and 10 min after anesthesia), at skin and uterine incision, newborn and placental delivery, oxytocin administration, end of surgery, and recovery from anesthesia. Hemodynamic therapy was guided by mean arterial pressure, and vasopressors were used as appropriate to maintain baseline values. A repeated measures ANOVA was used for data analysis. RESULTS: There was a significant increase in heart rate and a decrease of stroke volume and stroke volume index up to 10 min after spinal anesthesia (P < 0.01). Importantly, stroke volume variation increased immediately after newborn delivery (P < 0.001) and returned to basal values at the end of surgery. Further hemodynamic parameters showed no significant changes over time. DISCUSSION AND CONCLUSIONS: No significant hemodynamic effects, except for heart rate and stroke volume changes, were observed in pregnant women managed with preload and vasopressors when undergoing elective cesarean section and spinal anesthesia.

Auler, Jose Otavio C.; Torres, Marcelo L. A.; Cardoso, Monica M.; Tebaldi, Thais C.; Schmidt, Andre P.; Kondo, Mario M.; Zugaib, Marcelo

2010-01-01

126

Pulmonary carbon dioxide elimination for cardiac output monitoring in peri-operative and critical care patients: history and current status.  

PubMed

Minimally invasive measurement of cardiac output as a central component of advanced haemodynamic monitoring has been increasingly recognised as a potential means of improving perioperative outcomes in patients undergoing major surgery. Methods based upon pulmonary carbon dioxide elimination are among the oldest techniques in this field, with comparable accuracy and precision to other techniques. Modern adaptations of these techniques suitable for use in the perioperative and critical are environment are based on the differential Fick approach, and include the partial carbon dioxide rebreathing method. The accuracy and precision of this approach to cardiac output measurement has been shown to be similar to other minimally invasive techniques. This paper reviews the underlying principles and evolution of the method, and future directions including recent adaptations designed to deliver continuous breath-by-breath monitoring of cardiac output. PMID:23778012

Peyton, Philip J

2013-01-01

127

Heterotrimeric G Proteins Regulate a Noncanonical Function of Septate Junction Proteins to Maintain Cardiac Integrity in Drosophila  

Microsoft Academic Search

SUMMARY The gene networks regulating heart morphology and cardiac integrity are largely unknown. We previously reported a role for the heterotrimeric G protein gsub- unit 1 (Gg1) in mediating cardial-pericardial cell ad- hesion in Drosophila. Here we show G-oa47A and Gb13F cooperate with Gg1 to maintain cardiac in- tegrity. Cardial-pericardial cell adhesion also relies on the septate junction (SJ) proteins

Peng Yi; Aaron N. Johnson; Zhe Han; Jiang Wu; Eric N. Olson

2008-01-01

128

Multiple-model adaptive predictive control of mean arterial pressure and cardiac output.  

PubMed

A multiple-model adaptive predictive controller has been designed to simultaneously regulate mean arterial pressure and cardiac output in congestive heart failure subjects by adjusting the infusion rates of nitroprusside and dopamine. The algorithm is based on the multiple-model adaptive controller and utilizes model predictive controllers to provide reliable control in each model subspace. A total of 36 linear small-signal models were needed to span the entire space of anticipated responses. To reduce computation time, only the six models with the highest probabilities were used in the control calculations. The controller was evaluated on laboratory animals that were either surgically or pharmacologically altered to exhibit symptoms of congestive heart failure. During trials, the controller performance was robust with respect to excessive switching between models and nonconvergence to a single dominant model. A comparison is also made with a previous multiple-drug controller design. PMID:1505992

Yu, C; Roy, R J; Kaufman, H; Bequette, B W

1992-08-01

129

A fMRI Study of Verbal Working Memory, Cardiac Output, and Ejection Fraction in Elderly Patients with Cardiovascular Disease  

Microsoft Academic Search

Cardiovascular disease (CVD) is associated with cognitive deficits even in the absence of stroke. We examined the relationship\\u000a between cardiac performance, as measured by cardiac output (CO) and ejection fraction (EF), and brain activity during a verbal\\u000a working memory (VWM) task in elderly CVD patients who tend to be at increased risk for vascular cognitive impairments. Seventeen\\u000a patients were recruited

Farzin Irani; Lawrence H. Sweet; Andreana P. Haley; John J. Gunstad; Beth A. Jerskey; Richard C. Mulligan; Angela L. Jefferson; Athena Poppas; Ronald A. Cohen

2009-01-01

130

Influence of levosimendan, pimobendan, and milrinone on the regional distribution of cardiac output in anaesthetized dogs.  

PubMed Central

1. The distribution of cardiac output during administration of levosimendan, a new myofilament calcium sensitizer, is unknown. We examined and compared the effects of levosimendan, pimobendan, and milrinone on regional tissue perfusion by use of the radioactive microsphere technique in barbiturate-anaesthetized dogs. 2. Haemodynamics and regional blood flow were determined before and during infusions of levosimendan (0.75, 1.5, and 3.0 micrograms kg-1 min-1), pimobendan (10, 20, and 40 micrograms kg-1 min-1), or milrinone (1.0, 2.0, and 4.0 micrograms kg-1 min-1). 3. All three drugs caused similar increases in heart rate, cardiac output, and left ventricular +dP/dt and decreases in end-diastolic pressure and systemic vascular resistance. No changes in subendocardial, midmyocardial, and subepicardial blood flow occurred during administration of levosimendan. However, a redistribution of blood flow from subendocardium to subepicardium was observed. Pimobendan increased midmyocardial and subepicardial blood flow and reduced the endo/epi ratio to a greater degree than levosimendan. Milrinone did not affect myocardial perfusion. 4. Levosimendan increased blood flow to the renal medulla and decreased renal medullary and cortical vascular resistance. Levosimendan increased blood flow to the small intestine and liver and reduced vascular resistance in these organs. Pimobendan increased hepatic blood flow to a greater degree than levosimendan but did not alter small intestinal perfusion. All three drugs decreased splenic blood flow to similar degrees. Levosimendan and pimobendan reduced cerebral vascular resistance. Levosimendan and milrinone reduced skeletal muscle vascular resistance. 5. The results indicate that levosimendan, pimobendan, and milrinone cause subtlety different alterations in regional tissue perfusion while producing similar haemodynamic effects.

Pagel, P. S.; Hettrick, D. A.; Warltier, D. C.

1996-01-01

131

Equipment review: New techniques for cardiac output measurement - oesophageal Doppler, Fick principle using carbon dioxide, and pulse contour analysis  

PubMed Central

Measuring cardiac output is of paramount importance in the management of critically ill patients in the intensive care unit and of 'high risk' surgical patients in the operating room. Alternatives to thermodilution are now available and are gaining acceptance among practitioners who have been trained almost exclusively in the use of the pulmonary artery catheter. The present review focuses on the principles, advantages and limitations of oesophageal Doppler, Fick principle applied to carbon dioxide, and pulse contour analysis. No single method stands out or renders the others obsolete. By making cardiac output easily measurable, however, these techniques should all contribute to improvement in haemodynamic management.

Berton, Christine; Cholley, Bernard

2002-01-01

132

Comparison of calibrated and uncalibrated arterial pressure-based cardiac output monitors during orthotopic liver transplantation.  

PubMed

Arterial pressure-based cardiac output monitors (APCOs) are increasingly used as alternatives to thermodilution. Validation of these evolving technologies in high-risk surgery is still ongoing. In liver transplantation, FloTrac-Vigileo (Edwards Lifesciences) has limited correlation with thermodilution, whereas LiDCO Plus (LiDCO Ltd.) has not been tested intraoperatively. Our goal was to directly compare the 2 proprietary APCO algorithms as alternatives to pulmonary artery catheter thermodilution in orthotopic liver transplantation (OLT). The cardiac index (CI) was measured simultaneously in 20 OLT patients at prospectively defined surgical landmarks with the LiDCO Plus monitor (CI(L)) and the FloTrac-Vigileo monitor (CI(V)). LiDCO Plus was calibrated according to the manufacturer's instructions. FloTrac-Vigileo did not require calibration. The reference CI was derived from pulmonary artery catheter intermittent thermodilution (CI(TD)). CI(V)-CI(TD) bias ranged from -1.38 (95% confidence interval = -2.02 to -0.75 L/minute/m(2), P = 0.02) to -2.51 L/minute/m(2) (95% confidence interval = -3.36 to -1.65 L/minute/m(2), P < 0.001), and CI(L)-CI(TD) bias ranged from -0.65 (95% confidence interval = -1.29 to -0.01 L/minute/m(2), P = 0.047) to -1.48 L/minute/m(2) (95% confidence interval = -2.37 to -0.60 L/minute/m(2), P < 0.01). For both APCOs, bias to CI(TD) was correlated with the systemic vascular resistance index, with a stronger dependence for FloTrac-Vigileo. The capability of the APCOs for tracking changes in CI(TD) was assessed with a 4-quadrant plot for directional changes and with receiver operating characteristic curves for specificity and sensitivity. The performance of both APCOs was poor in detecting increases and fair in detecting decreases in CI(TD). In conclusion, the calibrated and uncalibrated APCOs perform differently during OLT. Although the calibrated APCO is less influenced by changes in the systemic vascular resistance, neither device can be used interchangeably with thermodilution to monitor cardiac output during liver transplantation. PMID:20517912

Krejci, Vladimir; Vannucci, Andrea; Abbas, Alhan; Chapman, William; Kangrga, Ivan M

2010-06-01

133

Role of cardiac output versus peripheral vasoconstriction in mediating muscle metaboreflex pressor responses: dynamic exercise versus postexercise muscle ischemia.  

PubMed

Muscle metaboreflex activation (MMA) during submaximal dynamic exercise in normal individuals increases mean arterial pressure (MAP) via increases in cardiac output (CO) with little peripheral vasoconstriction. The rise in CO occurs primarily via increases in heart rate (HR) with maintained or slightly increased stroke volume. When the reflex is sustained during recovery (postexercise muscle ischemia, PEMI), HR declines yet MAP remains elevated. The role of CO in mediating the pressor response during PEMI is controversial. In seven chronically instrumented canines, steady-state values with MMA during mild exercise (3.2 km/h) were observed by reducing hindlimb blood flow by ~60% for 3-5 min. MMA during exercise was followed by 60 s of PEMI. Control experiments consisted of normal exercise and recovery. MMA during exercise increased MAP, HR, and CO by 55.3 ± 4.9 mmHg, 42.5 ± 6.9 beats/min, and 2.5 ± 0.4 l/min, respectively. During sustained MMA via PEMI, MAP remained elevated and CO remained well above the normal recovery levels. Neither MMA during dynamic exercise nor during PEMI significantly affected peripheral vascular conductance. We conclude that the sustained increase in MAP during PEMI is driven by a sustained increase in CO not peripheral vasoconstriction. PMID:23427084

Spranger, Marty D; Sala-Mercado, Javier A; Coutsos, Matthew; Kaur, Jasdeep; Stayer, Doug; Augustyniak, Robert A; O'Leary, Donal S

2013-02-20

134

Enhanced cardiac thermal dilution measurement of cardiac output, volumes, regurgitation, valve effective diameters, ventricular power and efficiency -- Feasibility analysis using digital simulation.  

PubMed

Cardiac output is measured by the thermal dilution method which uses a quadruple lumen catheter, with a thermistor on the tip, through the right atrium, right ventricle and into the pulmonary artery. Cold saline is injected into the right atrium and the resulting pulmonary artery temperature profile is integrated. The same procedure performed with three thermistors and three pressure sensors located on the catheter to measure temperature and pressure in the atrium, ventricle and artery respectively will produce a set of temperature and pressure curves with shapes determined by injectate temperature, injectate volume, heart rate, systolic time interval, body temperature, cardiac output, volumes, flow rates and valve openings. A digital computer program has been developed to optimize the fit of a lumped parameter model to the thermodilution curves in order to determine heart rate, systolic time as a fraction of cardiac cycle, right atrial systolic and diastolic volumes, ventricular systolic and diastolic volumes, cardiac output, inflow valve forward and reverse flow rates and effective diameters, outflow valve forward and reverse flow rates and effective diameters, ventricular power and efficiency. The program has been tested over a range of operating conditions including noise in the temperature and pressure signals, randomly varying heart rate and cardiac cycle. All of the data for the tests were produced by a digital computer simulation of a pulsatile artificial heart. The results of these tests indicate that the enhanced thermal dilution analysis method is feasible. PMID:11673669

Donovan, F M; Taylor, B C

2001-01-01

135

Non-invasive determination of stroke volume and cardiac output after high intensity playing exercise in elite female soccer players  

Microsoft Academic Search

BackgroundStroke volume (SV) and heart rate (HR), determining cardiac output (CO), are crucial hemodynamic parameters determining training adoptions to endurance training. In soccer, aerobic power as well as intermittent exercise performance varies significantly among level of competition as well as playing position. In this study cohort study we thought to determine the hemodynamic changes following a standardized soccer-specific exercise in

Karsten Knobloch

2009-01-01

136

Combined use of phenoxybenzamine and dopamine for low cardiac output syndrome in children at withdrawal from cardiopulmonary bypass  

Microsoft Academic Search

The combined use of phenoxybenzamine and dopamine was applied in infants and children when it was difficult to come off cardiopulmonary bypass for low cardiac output. The rationale of this method is to prevent the alpha-adrenergic action of dopamine by phenoxybenzamine and to encourage the beta-adrenergic and direct specific action of dopamine. Dopamine was used in dosage of 10 to

M Kawamura; O Minamikawa; H Yokochi; S Maki; T Yasuda; Y Mizukawa

1980-01-01

137

Interrelationship between cardiac output and vascular resistance as determinants of effective arterial blood volume in cirrhotic patients  

Microsoft Academic Search

Interrelationship between cardiac output and vascular resistance as determinants of effective arterial blood volume in cirrhotic patients. The effect of head-out water immersion (HWI) in decompensated cirrhotic patients to correct sodium and water excretion has been found to be incomplete and variable. The explanation may be that the efficacy of HWI in correcting a decreased effective arterial blood volume (EABV)

Michael D Shapiro; Kathleen M Nicholls; Bertron M Groves; Rudiger Kluge; Hsaio-Min Chung; Daniel G Bichet; Robert W Schrier

1985-01-01

138

Performance of a minimally invasive uncalibrated cardiac output monitoring system (FlotracTM\\/VigileoTM) in haemodynamically unstable patients  

Microsoft Academic Search

Background. Early haemodynamic assessment is of particular importance in the evaluation of haemodynamically compromised patients, but is often precluded by the invasiveness and com- plexity of the established cardiac output (CO) monitoring techniques. The FloTrac TM \\/Vigileo TM system allows minimally invasive CO determination based on the arterial pressure waveform derived from any standard arterial catheter, and the algorithm underlying

F. D. Compton; B. Zukunft; C. Hoffmann; W. Zidek; J.-H. Schaefer

2008-01-01

139

Cardiac Output Measurement in Patients Undergoing Liver Transplantation: Pulmonary Artery Catheter Versus Uncalibrated Arterial Pressure Waveform Analysis  

Microsoft Academic Search

BACKGROUND: Cardiac output (CO) and invasive hemodynamic measurements are useful during liver transplantation. The pulmonary artery catheter (PAC) is commonly used for these patients, despite the potential complications. Recently, a less invasive device (Vigileo®\\/FloTrac™) became available, which estimates CO using arterial pressure waveform analysis without external calibration. In this study, we compared CO obtained with a PAC using automatic thermodilution,

Biais Matthieu; Nouette-Gaulain Karine; Cottenceau Vincent; Vallet Alain; Cochard Jean François; Revel Philippe; Sztark François

2008-01-01

140

The Effects of Spread of Block and Adrenaline on Cardiac Output After Epidural Anesthesia in Young Children: A Randomized, Double-Blind, Prospective Study  

Microsoft Academic Search

Epidural anesthesia is considered to be without signifi- cant hemodynamic consequence in young children. However, conversely to adults, few studies have inves- tigated cardiac output. Using transesophageal Doppler monitoring of cardiac output, we prospectively investi- gated hemodynamic alterations in 48 children (median age, 22.5 mo) receiving sevoflurane general anesthesia combined with caudal or thoracolumbar epidural anes- thesia. They were randomly

Olivier Raux; Alain Rochette; Estelle Morau; Christophe Dadure; Christine Vergnes; Xavier Capdevila

2004-01-01

141

Regional blood flow in chronic heart failure: the reason for the lack of correlation between patients' exercise tolerance and cardiac output?  

Microsoft Academic Search

BACKGROUND--In patients with chronic heart failure there is no relation between cardiac output and symptom limited exercise tolerance measured on a bicycle or treadmill. Furthermore, the increase in cardiac output in response to treatment may not be matched by a similar increase in exercise tolerance. More important in determining exercise capability is blood flow to skeletal muscle. This implies that

A F Muller; P Batin; S Evans; M Hawkins; A J Cowley

1992-01-01

142

Effects of velocity distribution, diameter measurement and velocity tracing on the accuracy of cardiac output measurement by pulsed doppler echocardiography in the aortic annulus of pigs  

Microsoft Academic Search

The accuracy of cardiac output measurement by pulsed Doppler echocardiography can be affected by several factors, such as the velocity distribution, the measurement of diameter and the method of tracing the pulsed Doppler flow spectrum. This experimental study was designed to find the most accurate way of measuring cardiac output in consideration of all these factors. In 10 open-chest normal

Yu-Qing Zhou; Svein Faerestrand; Sigurd Birkeland; Knut Matre; Paul Husby; Mai-Elin Koller

1997-01-01

143

Estimation of cardiac output and peripheral resistance using square-wave-approximated aortic flow signal  

PubMed Central

This paper presents a model-based approach to estimation of cardiac output (CO) and total peripheral resistance (TPR). In the proposed approach, the response of cardiovascular system (CVS), described by the windkessel model, is tuned to the measurements of systolic, diastolic and mean arterial blood pressures (BP) so as to yield optimal individual- and time-specific system time constant that is used to estimate CO and TPR. Unique aspects of the proposed approach are that it approximates the aortic flow as a train of square waves and that it also assumes pressure-dependent arterial compliance, as opposed to the traditional windkessel model in which aortic flow is approximated as a train of impulses and constant arterial compliance is assumed. It was shown that the proposed model encompasses the standard windkessel model as a limiting case, and that it also yields more realistic BP waveform response than the standard windkessel model. The proposed approach has potential to outperform its standard counterpart by treating systolic, diastolic, and mean BP as independent features in estimating CO and TPR, rather than solely resorting to pulse pressure as in the case of the standard windkessel model. Experimental results from in-vivo data collected from a number of animal subjects supports the viability of the proposed approach in that it could achieve approximately 29% and 24% reduction in CO and TPR errors when compared with its standard counterpart.

Fazeli, Nima; Hahn, Jin-Oh

2012-01-01

144

Non-invasive measurement of cardiac output: evaluation of new infrared absorption spectrometer.  

PubMed

The mass spectrometer (MS) traditionally has been the instrument of choice for measuring cardiac output (Q (T)) non-invasively using the foreign gas uptake method. However, the size and cost of the MS has hampered widespread adoption of this technique outside of the laboratory. Here, we present results, from six normal human subjects at rest and during exercise, of simultaneous Q (T) measurements by an MS and a new, portable infrared (IR) device developed in our laboratories. These measurements are made using on the open-circuit acetylene uptake method. The IR device measures inspired and end-tidal concentrations of acetylene, sulfur hexafluoride, and carbon dioxide by IR absorption spectroscopy with a 10-90% response time of 43 ms; accurate measurements were made down to sample flow rates of 50 mL min(-1). Excellent correlation [Q (T)(IR)=0.98 Q (T)(MS), R(2)=0.94] was observed between instruments across the range from rest to heavy exercise. These results suggest that the IR device, which is small, light-weight, and rugged may enable the foreign gas uptake method to be used in clinical, field, and point-of-care settings for Q (T) measurement. PMID:16326150

Baum, M M; Moss, J A; Kumar, S; Wagner, P D

2005-12-02

145

Evaluation of coronary blood flow velocity during cardiac arrest with circulation maintained through mechanical chest compressions in a porcine model  

PubMed Central

Background Mechanical chest compressions (CCs) have been shown capable of maintaining circulation in humans suffering cardiac arrest for extensive periods of time. Reports have documented a visually normalized coronary blood flow during angiography in such cases (TIMI III flow), but it has never been actually measured. Only indirect measurements of the coronary circulation during cardiac arrest with on-going mechanical CCs have been performed previously through measurement of the coronary perfusion pressure (CPP). In this study our aim was to correlate average peak coronary flow velocity (APV) to CPP during mechanical CCs. Methods In a closed chest porcine model, cardiac arrest was established through electrically induced ventricular fibrillation (VF) in eleven pigs. After one minute, mechanical chest compressions were initiated and then maintained for 10 minutes upon which the pigs were defibrillated. Measurements of coronary blood flow in the left anterior descending artery were made at baseline and during VF with a catheter based Doppler flow fire measuring APV. Furthermore measurements of central (thoracic) venous and arterial pressures were also made in order to calculate the theoretical CPP. Results Average peak coronary flow velocity was significantly higher compared to baseline during mechanical chests compressions and this was observed during the entire period of mechanical chest compressions (12 - 39% above baseline). The APV slowly declined during the 10 min period of mechanical chest compressions, but was still higher than baseline at the end of mechanical chest compressions. CPP was simultaneously maintained at > 20 mmHg during the 10 minute episode of cardiac arrest. Conclusion Our study showed good correlation between CPP and APV which was highly significant, during cardiac arrest with on-going mechanical CCs in a closed chest porcine model. In addition APV was even higher during mechanical CCs compared to baseline. Mechanical CCs can, at minimum, re-establish coronary blood flow in non-diseased coronary arteries during cardiac arrest.

2011-01-01

146

Comparison of bedside measurement of cardiac output with the thermodilution method and the Fick method in mechanically ventilated patients  

PubMed Central

Introduction Bedside cardiac output determination is a common preoccupation in the critically ill. All available methods have drawbacks. We wished to re-examine the agreement between cardiac output determined using the thermodilution method (QTTHERM) and cardiac output determined using the metabolic (Fick) method (QTFICK) in patients with extremely severe states, all the more so in the context of changing practices in the management of patients. Indeed, the interchangeability of the methods is a clinically relevant question; for instance, in view of the debate about the risk–benefit balance of right heart catheterization. Patients and methods Eighteen mechanically ventilated passive patients with a right heart catheter in place were studied (six women, 12 men; age, 39–84 years; simplified acute physiology scoreII, 39–111). QTTHERM was obtained using a standard procedure. QTFICK was measured from oxygen consumption, carbon dioxide production, and arterial and mixed venous oxygen contents. Forty-nine steady-state pairs of measurements were performed. The data were normalized for repeated measurements, and were tested for correlation and agreement. Results The QTFICK value was 5.2 ± 2.0 l/min whereas that of QTTHERM was 5.8 ± 1.9 l/min (R = 0.840, P < 0.0001; mean difference, -0.7 l/min; lower limit of agreement, -2.8 l/min; upper limit of agreement, 1.5 l/min). The agreement was excellent between the two techniques at QTTHERM values <5 l/min but became too loose for clinical interchangeability above this value. Tricuspid regurgitation did not influence the results. Discussion and conclusions No gold standard is established to measure cardiac output in critically ill patients. The thermodilution method has known limitations that can lead to inaccuracies. The metabolic method also has potential pitfalls in this context, particularly if there is increased oxygen consumption within the lungs. The concordance between the two methods for low cardiac output values suggests that they can both be relied upon for clinical decision making in this context. Conversely, a high cardiac output value is more difficult to rely on in absolute terms.

Gonzalez, Jesus; Delafosse, Christian; Fartoukh, Muriel; Capderou, Andre; Straus, Christian; Zelter, Marc; Derenne, Jean-Philippe; Similowski, Thomas

2003-01-01

147

Semi-invasive monitoring of cardiac output by a new device using arterial pressure waveform analysis: a comparison with intermittent pulmonary artery thermodilution in patients undergoing cardiac surgery  

Microsoft Academic Search

Background. Thermodilution technique using a pulmonary artery catheter (PAC) is a widely used method to determine cardiac output (CO). It is increasingly criticized because of its inva- siveness and its unclear risk-benefit ratio. Thus, less invasive techniques for measuring CO are highly desirable. We compared a new, semi-invasive device (FloTrac\\/VigileoTM) using arterial pressure waveform analysis for CO measurement in patients

J. Mayer; J. Boldt; T. Schollhorn; K. D. Rohm; A. M. Mengistu; S. Suttner

2007-01-01

148

Heterotrimeric G proteins regulate a noncanonical function of septate junction proteins to maintain cardiac integrity in Drosophila.  

PubMed

The gene networks regulating heart morphology and cardiac integrity are largely unknown. We previously reported a role for the heterotrimeric G protein gamma subunit 1 (Ggamma1) in mediating cardial-pericardial cell adhesion in Drosophila. Here we show G-oalpha47A and Gbeta13F cooperate with Ggamma1 to maintain cardiac integrity. Cardial-pericardial cell adhesion also relies on the septate junction (SJ) proteins Neurexin-IV (Nrx-IV), Sinuous, Coracle, and Nervana2, which together function in a common pathway with Ggamma1. Furthermore, Ggamma1 signaling is required for proper SJ protein localization, and loss of at least one SJ protein, Nrx-IV, induces cardiac lumen collapse. These results are surprising because the embryonic heart lacks SJs and suggest that SJ proteins perform noncanonical functions to maintain cardiac integrity in Drosophila. Our findings unveil the components of a previously unrecognized network of genes that couple G protein signaling with structural constituents of the heart. PMID:19000835

Yi, Peng; Johnson, Aaron N; Han, Zhe; Wu, Jiang; Olson, Eric N

2008-11-01

149

Evaluation of a noninvasive continuous cardiac output monitoring system based on thoracic bioreactance.  

PubMed

Noninvasive cardiac output (CO) measurement can be useful in many clinical settings where invasive monitoring is not desired. Bioimpedance (intrabeat measurement of changes in transthoracic voltage amplitude in response to an injected high-frequency current) has been explored for this purpose but is limited in some clinical settings because of inherently low signal-to-noise ratio. Since changes in fluid content also induce changes in thoracic capacitive and inductive properties, we tested whether a noninvasive CO measurement could be obtained through measurement of the relative phase shift of an injected current (i.e., bioreactance). We constructed a prototype device that applies a 75-kHz current and determines the relative phase shift (dPhi/dt) of the recorded transthoracic voltage. CO was related to the product of peak dPhi/dt, heart rate, and ventricular ejection time. The preclinical study was done in nine open-chest pigs put on right heart bypass so that CO could be varied at known values. This was followed by a feasibility study in 27 postoperative patients who had a Swan-Ganz catheter (SGC). The measurements of noninvasive CO measurement and cardiopulmonary bypass pump correlated to each other (r = 0.84) despite the large variation in CO and temperatures. Similarly, in patients, mean CO values were 5.18 and 5.17 l/min as measured by SGC and the noninvasive CO measurement system, respectively, and were highly correlated over the range of values studied (r = 0.90). Preclinical and clinical data demonstrate the feasibility of using blood flow-related phase shifts of transthoracic electric signals to perform noninvasive continuous CO monitoring. PMID:17384132

Keren, Hanan; Burkhoff, Daniel; Squara, Pierre

2007-03-23

150

Cardiac output distribution in miniature swine during locomotory exercise to VO/sub 3max/  

SciTech Connect

Distribution of cardiac output (CO) was studied in miniature swine (22 +/- 1 kg) during level treadmill exercise up to the speed (17.7 km/hr) that elicited maximal oxygen consumption (VO/sub 2max/) (60 +/- 4 m1/min/kg). COs and tissue blood flows (BFs) were measured with the radiolabelled microsphere technique. CO increased from a preexercise value of 2.1 +/- 0.5 1/min up to 9.9 +/- 0.5 1/min at VO/sub 2max/. In preexercise standing 43% of CO went to skeletal muscle, which comprised 36 +/- 1% of body mass, 42% to viscera (12 +/- 1% mass), 5% to brain, heart, and lungs (2% +/- 0.1% mass), and 10% to skin and skeleton (35 +/- 2% mass). Preexercise could not be considered resting because of the animals' excitability. Skeletal muscle BF increased progressively with speed up to VO/sub 2max/, both in absolute terms and in percent CO. At VO/sub 2max/, 88% of CO went to muscle, 3% to viscera, 8% to brain, heart and lungs, and 1% to skin and skeleton. Thus, at VO/sub 2max/ only 4% of CO went to the inactive tissues, which constituted 47% of body mass. In 2 pigs that ran at speeds above 17 km/hr, total muscle BF leveled off at VO/sub 2max/. These findings demonstrate that muscle BF progressively increases up to VO/sub 2max/, and that VO/sub 2/ levels off at the same intensity as muscle flow.

Armstrong, R.B.; Delp, M.D.; Laughlin, M.H.

1986-03-01

151

Transpulmonary transit of microbubbles during contrast echocardiography: implications for estimating cardiac output and pulmonary blood volume.  

PubMed

We postulated that the pulmonary transit rate of sonicated albumin microbubbles, which have an intravascular rheology similar to that of red blood cells, would be directly proportional to cardiac output (CO) and inversely proportional to pulmonary blood volume (PBV). Accordingly, 4 ml of Albunex ultrasound contrast agent (0.5 billion/ml of 4.3 mu bubbles) was injected into the right atrium of six dogs (Group I) during simultaneously performed two-dimensional echocardiography, and the time between the initial appearance of the bubbles in the right and left ventricle, respectively, was measured. CO was either increased (by intravenous infusion of 15 micrograms/kg/min of dobutamine) or decreased (by producing left ventricular ischemia or by administering 2 mg of intravenous propranolol) in a random order and microbubbles were injected again. At each stage, thermodilution CO was measured. There was a close linear relation between CO and pulmonary transit rate of Albunex in each dog with the correlation coefficient ranging from 0.79 to 0.99, with a mean of 0.92. Pulmonary blood volume was derived in each dog from the reciprocal of the slope of the regression between CO and pulmonary transit rate and varied from 106 to 261 ml in the six dogs with a mean value of 178 +/- 64 ml. There was excellent interobserver and intraobserver correlation (r = 0.99 each) for determining the pulmonary transit rate of Albunex. The reproducibility of pulmonary transit rate estimation from repeated contrast injections at the same hemodynamic state in another group of six dogs (Group II) was also good (r = 0.99). It is concluded that the pulmonary transit rate of Albunex ultrasound contrast agent can be used to assess directional changes in CO and to measure pulmonary blood volume. This method may have clinical applications. PMID:8333975

Galanti, G; Jayaweera, A R; Villanueva, F S; Glasheen, W P; Ismail, S; Kaul, S

152

A comparison of pulse contour wave analysis and ultrasonic cardiac output monitoring in the critically ill.  

PubMed

Cardiac output (CO) is a key determinant of major organ blood flow and solute delivery to drug eliminating organs. As such, CO assessment is a key covariate in understanding altered drug handling in the critically ill. Newer minimally-invasive devices are providing unique platforms for such an application, although comparison data are currently lacking. In this study we evaluated the Vigileo (Edwards Lifesciences, Irvine, CA, USA) and USCOM (USCOM Ltd, Sydney, NSW) devices in 62 critically ill patients requiring antibacterial therapy. The mean COVigileo and COUSCOM for the first paired measurements were 8.20±2.65 l/minute and 6.84±2.57 l/minute respectively (P <0.001). A significant correlation was evident in all patients (r=0.537, P <0.001) although the recorded bias was large (1.36±2.51 l/minute, limits of agreement -3.6 to±6.3 l/minute). The overall percentage error was 65%. There was an improved correlation in those admitted with sepsis (r=0.639, P <0.001), compared to trauma (r=0.373, P=0.066), although bias, precision and percentage error were similar in both subgroups. In 54 patients a second paired assessment was obtained at three hours. A weak, although significant correlation (r=0.377, P=0.005) was observed suggesting that gross trends over time were similar. In conclusion, our findings demonstrate poor agreement between these techniques suggesting that these devices are not simply interchangeable when assessing CO in a research or clinical setting. PMID:22813490

Udy, A A; Altukroni, M; Jarrett, P; Roberts, J A; Lipman, J

2012-07-01

153

Monitoring non-invasive cardiac output and stroke volume during experimental human hypovolaemia and resuscitation  

PubMed Central

Background Multiple methods for non-invasive measurement of cardiac output (CO) and stroke volume (SV) exist. Their comparative capabilities are not clearly established. Methods Healthy human subjects (n=21) underwent central hypovolaemia through progressive lower body negative pressure (LBNP) until the onset of presyncope, followed by termination of LBNP, to simulate complete resuscitation. Measurement methods were electrical bioimpedance (EBI) of the thorax and three measurements of CO and SV derived from the arterial blood pressure (ABP) waveform: the Modelflow (MF) method, the long-time interval (LTI) method, and pulse pressure (PP). We computed areas under receiver-operating characteristic curves (ROC AUCs) for the investigational metrics, to determine how well they discriminated between every combination of LBNP levels. Results LTI and EBI yielded similar reductions in SV during progressive hypovolaemia and resuscitation (correlation coefficient 0.83) with ROC AUCs for distinguishing major LBNP (?60 mm Hg) vs resuscitation (0 mm Hg) of 0.98 and 0.99, respectively. MF yielded very similar reductions and ROC AUCs during progressive hypovolaemia, but after resuscitation, MF-CO did not return to baseline, yielding lower ROC AUCs (?ROC AUC range, ?0.18 to ?0.26, P<0.01). PP declined during hypovolaemia but tended to be an inferior indicator of specific LBNP levels, and PP did not recover during resuscitation, yielding lower ROC curves (P<0.01). Conclusions LTI, EBI, and MF were able to track progressive hypovolaemia. PP decreased during hypovolaemia but its magnitude of reduction underestimated reductions in SV. PP and MF were inferior for the identification of resuscitation.

Reisner, A. T.; Xu, D.; Ryan, K. L.; Convertino, V. A.; Rickards, C. A.; Mukkamala, R.

2011-01-01

154

Control of right atrial pressure at constant cardiac output suppresses volume natriuresis in anesthetized rats.  

PubMed

The blood volume of anesthetized rats was expanded acutely by 33% with donor blood while a caval snare was gradually tightened so that right atrial pressure (RAP) was prevented from rising (n = 6). In control experiments (n = 5) an aortic snare was used to hold mean arterial blood pressure near the values found in the experimental series. However, RAP was allowed to change freely and increased by 1.6 +/- 0.4 mmHg (1 mmHg = 133.322 Pa) during volume expansion. When the two groups were compared, there were no significant differences between their mean arterial blood pressures (near 110 mmHg) or in their cardiac outputs (near 0.25 mL X min-1 X g body weight-1). There were, however, significant differences between their renal responses to the volume load. When RAP was free to change, the rate of volume excretion (V) increased to 30 +/- 15 (SEM) microL X min-1 X g kidney weight-1 (KW) from its control value of 3.49 +/- 0.31 and the rate of sodium excretion (UNaV) increased to 3.59 +/- 0.20 muequiv X min-1 X g KW-1 from its preinfusion value of 0.42 +/- 0.10. When RAP was not allowed to increase during volume loading, V and UNaV did not change from their respective preinfusion values (2.99 +/- 0.46 microL X min-1 X g KW-1 and 0.35 +/- 0.10 muequiv X min-1 X g KW-1). The results imply that during acute blood volume expansion increased central vascular pressure is a prerequisite for the homeostasis of body water and salt. PMID:6498610

Ackermann, U; Rudolph, J R

1984-07-01

155

Clinical validation of cardiac output measurements using femoral artery thermodilution with direct Fick in ventilated children and infants  

Microsoft Academic Search

Objective: To validate clinically cardiac output (CO) measurements using femoral artery thermodilution in ventilated children and infants\\u000a by comparison with CO estimated from the Fick equation via a metabolic monitor. Design: Prospective, comparison study. Setting: Paediatric intensive care unit of a university hospital. Patients: 24 ventilated infants and children, aged 0.3 to 175 months (median age 19 months). Interventions: Oxygen

S. M. Tibby; M. Hatherill; M. J. Marsh; G. Morrison; D. Anderson; I. A. Murdoch

1997-01-01

156

The use of the electrical-impedance technique for the monitoring of cardiac output and limb bloodflow during anaesthesia  

Microsoft Academic Search

A need has long existed during routine anaesthesia for a convenient, noninvasive method for the monitoring of stroke volume,\\u000a and hence of changes in cardiac output. If knowledge of the mean arterial blood pressure is available, it becomes possible\\u000a to monitor changes occurring in the left-ventricular stroke work and the total systemic resistance. Nyboer et al. (1940) proposed\\u000a the use

D. W. Hill; H. J. Lowe

1973-01-01

157

Cardiac output measurement by transpulmonary versus conventional thermodilution technique in intensive care patients after coronary artery bypass grafting  

Microsoft Academic Search

Objective: The aim of the present study was to evaluate the correlation, accuracy, and precision of transpulmonary thermodilution cardiac output (CO) measurement. For this purpose, this technique was compared with the clinical gold standard, the CO measurement by pulmonary artery catheter in patients after coronary artery bypass grafting (CABG).Design: A prospective clinical study.Setting: A university medical center.Participants: Seventy-five patients in

René Gust; André Gottschalk; Harald Bauer; Bernd W. Böttiger; Hubert Böhrer; Eike Martin

1998-01-01

158

Development and in vitro validation of a device for measuring non-shunt cardiac output by nitrous oxide throughflow  

Microsoft Academic Search

A system has been developed for measuring non-shunt cardiac output by the throughflow technique, using nitrous oxide in patients\\u000a undergoing general anaesthesia. The throughflow measurement technique is a non-invasive method based on inert gas throughflow\\u000a theory. In vitro validation of the measurement system was performed using a lung gas exchange simulator. The accuracy and\\u000a precision of the throughflow measurement system

G. M. Vartuli; R. B. Burfoot; G. J. B. Robinson; P. J. Peyton; P. A. Junor

2002-01-01

159

Cardiac Output, Renal Blood Flow and Hepatic Blood Flow in Rats with Glycerol-Induced Acute Renal Failure  

Microsoft Academic Search

Cardiac output (CO), renal blood flow (RBF) and hepatic blood flow (HBF) were measured by the microsphere method before (control) and at 4 and 10 h after the induction of acute renal failure by intramuscular injection of glycerol in water-drinking, long-term saline-drinking and long-term captopril (converting enzyme inhibitor)-drinking rats. At 4 h after glycerol injection, CO, RBF and HBF significantly

T. Kishimoto; W. Sakamoto; T. Nakatani; T. Ito; K. Iwai; T. Kim; Y. Abe

1989-01-01

160

Effects of Endothelin1 and Endothelin1 Receptor Blockade on Cardiac Output, Aortic Pressure, and Pulse Wave Velocity in Humans  

Microsoft Academic Search

Endothelin-1 (ET-1) is a potent vasoconstrictor. Its effect on arterial wave reflections and central pressure augmentation is unknown. We studied whether ET-1, in plasma concentrations present in disease, increases pulse wave velocity (PWV) and augmentation index (AIx) and therefore compromises cardiac output, and whether the ET-1 receptor blocker VML-588 (previously AXV-034343 and Ro 61-1790) prevents such effects. Nine healthy men

Tycho J. L. Vuurmans; Peter Boer; Hein A. Koomans

161

[Reliability of a less-invasive cardiac output monitor in the perioperative period of a patient with severe dilated cardiomyopathy].  

PubMed

Recently, various less-invasive cardiac output monitors are used for a variety of cases. We used FloTrac system for a patient with severe dilated cardiomyopathy (LVDd/Ds = 75/62 mm, EF = 22%) and recognized its limitation. A 52-year-old woman underwent left partial mastectomy. There were no significant events during the operation. In the ICU, she developed symptoms of low output state, but we could not detect any significant changes on Vigileo Monitor. Arterial pressure-based cardiac output (APCO) measurement with FloTrac is based on the patient's characteristics, blood pressure waveform and basic data stored in Vigileo Monitor. Its accuracy is worse with arterial wave artifact, compromise of the arterial catheter, aortic regurgitation, intense peripheral vasoconstriction, irregular pulse and severe cardiac hypofunction. Thus, its reliability is influenced by various conditions, especially in critically ill patients. FloTrac system is very useful for the management of cardiocirculatory dynamics, but we should be familiar with its limitations. PMID:21384657

Sotomi, Yohei; Nishiyama, Chie; Shimizu, Tomoaki; Kita, Takashi; Maki, Naritoshi; Sasaki, Shigeta

2011-02-01

162

Pulmonary Artery Catheter (PAC) Accuracy and Efficacy Compared with Flow Probe and Transcutaneous Doppler (USCOM): An Ovine Cardiac Output Validation  

PubMed Central

Background. The pulmonary artery catheter (PAC) is an accepted clinical method of measuring cardiac output (CO) despite no prior validation. The ultrasonic cardiac output monitor (USCOM) is a noninvasive alternative to PAC using Doppler ultrasound (CW). We compared PAC and USCOM CO measurements against a gold standard, the aortic flow probe (FP), in sheep at varying outputs. Methods. Ten conscious sheep, with implanted FPs, had measurements of CO by FP, USCOM, and PAC, at rest and during intervention with inotropes and vasopressors. Results. CO measurements by FP, PAC, and USCOM were 4.0 ± 1.2?L/min, 4.8 ± 1.5?L/min, and 4.0 ± 1.4?L/min, respectively, (n = 280, range 1.9?L/min to 11.7?L/min). Percentage bias and precision between FP and PAC, and FP and USCOM was ?17 and 47%, and 1 and 36%, respectively. PAC under-measured Dobutamine-induced CO changes by 20% (relative 66%) compared with FP, while USCOM measures varied from FP by 3% (relative 10%). PAC reliably detected ?30% but not +40% CO changes, as measured by receiver operating characteristic area under the curve (AUC), while USCOM reliably detected ±5% changes in CO (AUC > 0.70). Conclusions. PAC demonstrated poor accuracy and sensitivity as a measure of CO. USCOM provided equivalent measurements to FP across a sixfold range of outputs, reliably detecting ±5% changes.

Phillips, Robert A.; Hood, Sally G.; Jacobson, Beverley M.; West, Malcolm J.; Wan, Li; May, Clive N.

2012-01-01

163

Simple suspension culture system of human iPS cells maintaining their pluripotency for cardiac cell sheet engineering.  

PubMed

In this study, a simple three-dimensional (3D) suspension culture method for the expansion and cardiac differentiation of human induced pluripotent stem cells (hiPSCs) is reported. The culture methods were easily adapted from two-dimensional (2D) to 3D culture without any additional manipulations. When hiPSCs were directly applied to 3D culture from 2D in a single-cell suspension, only a few aggregated cells were observed. However, after 3?days, culture of the small hiPSC aggregates in a spinner flask at the optimal agitation rate created aggregates which were capable of cell passages from the single-cell suspension. Cell numbers increased to approximately 10-fold after 12?days of culture. The undifferentiated state of expanded hiPSCs was confirmed by flow cytometry, immunocytochemistry and quantitative RT-PCR, and the hiPSCs differentiated into three germ layers. When the hiPSCs were subsequently cultured in a flask using cardiac differentiation medium, expression of cardiac cell-specific genes and beating cardiomyocytes were observed. Furthermore, the culture of hiPSCs on Matrigel-coated dishes with serum-free medium containing activin A, BMP4 and FGF-2 enabled it to generate robust spontaneous beating cardiomyocytes and these cells expressed several cardiac cell-related genes, including HCN4, MLC-2a and MLC-2v. This suggests that the expanded hiPSCs might maintain the potential to differentiate into several types of cardiomyocytes, including pacemakers. Moreover, when cardiac cell sheets were fabricated using differentiated cardiomyocytes, they beat spontaneously and synchronously, indicating electrically communicative tissue. This simple culture system might enable the generation of sufficient amounts of beating cardiomyocytes for use in cardiac regenerative medicine and tissue engineering. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23728860

Haraguchi, Yuji; Matsuura, Katsuhisa; Shimizu, Tatsuya; Yamato, Masayuki; Okano, Teruo

2013-06-01

164

Diesel exhaust inhalation increases cardiac output, bradyarrhythmias, and parasympathetic tone in aged heart failure-prone rats.  

PubMed

Acute air pollutant inhalation is linked to adverse cardiac events and death, and hospitalizations for heart failure. Diesel engine exhaust (DE) is a major air pollutant suspected to exacerbate preexisting cardiac conditions, in part, through autonomic and electrophysiologic disturbance of normal cardiac function. To explore this putative mechanism, we examined cardiophysiologic responses to DE inhalation in a model of aged heart failure-prone rats without signs or symptoms of overt heart failure. We hypothesized that acute DE exposure would alter heart rhythm, cardiac electrophysiology, and ventricular performance and dimensions consistent with autonomic imbalance while increasing biochemical markers of toxicity. Spontaneously hypertensive heart failure rats (16 months) were exposed once to whole DE (4h, target PM(2.5) concentration: 500 µg/m(3)) or filtered air. DE increased multiple heart rate variability (HRV) parameters during exposure. In the 4h after exposure, DE increased cardiac output, left ventricular volume (end diastolic and systolic), stroke volume, HRV, and atrioventricular block arrhythmias while increasing electrocardiographic measures of ventricular repolarization (i.e., ST and T amplitudes, ST area, T-peak to T-end duration). DE did not affect heart rate relative to air. Changes in HRV positively correlated with postexposure changes in bradyarrhythmia frequency, repolarization, and echocardiographic parameters. At 24h postexposure, DE-exposed rats had increased serum C-reactive protein and pulmonary eosinophils. This study demonstrates that cardiac effects of DE inhalation are likely to occur through changes in autonomic balance associated with modulation of cardiac electrophysiology and mechanical function and may offer insights into the adverse health effects of traffic-related air pollutants. PMID:23047911

Carll, Alex P; Lust, Robert M; Hazari, Mehdi S; Perez, Christina M; Krantz, Quentin Todd; King, Charly J; Winsett, Darrell W; Cascio, Wayne E; Costa, Daniel L; Farraj, Aimen K

2012-10-09

165

Simultaneous determination of the accuracy and precision of closed-circuit cardiac output rebreathing techniques.  

PubMed

Foreign and soluble gas rebreathing methods are attractive for determining cardiac output (Q(c)) because they incur less risk than traditional invasive methods such as direct Fick and thermodilution. We compared simultaneously obtained Q(c) measurements during rest and exercise to assess the accuracy and precision of several rebreathing methods. Q(c) measurements were obtained during rest (supine and standing) and stationary cycling (submaximal and maximal) in 13 men and 1 woman (age: 24 +/- 7 yr; height: 178 +/- 5 cm; weight: 78 +/- 13 kg; Vo(2max): 45.1 +/- 9.4 ml.kg(-1).min(-1); mean +/- SD) using one-N(2)O, four-C(2)H(2), one-CO(2) (single-step) rebreathing technique, and two criterion methods (direct Fick and thermodilution). CO(2) rebreathing overestimated Q(c) compared with the criterion methods (supine: 8.1 +/- 2.0 vs. 6.4 +/- 1.6 and 7.2 +/- 1.2 l/min, respectively; maximal exercise: 27.0 +/- 6.0 vs. 24.0 +/- 3.9 and 23.3 +/- 3.8 l/min). C(2)H(2) and N(2)O rebreathing techniques tended to underestimate Q(c) (range: 6.6-7.3 l/min for supine rest; range: 16.0-19.1 l/min for maximal exercise). Bartlett's test indicated variance heterogeneity among the methods (P < 0.05), where CO(2) rebreathing consistently demonstrated larger variance. At rest, most means from the noninvasive techniques were +/-10% of direct Fick and thermodilution. During exercise, all methods fell outside the +/-10% range, except for CO(2) rebreathing. Thus the CO(2) rebreathing method was accurate over a wider range (rest through maximal exercise), but was less precise. We conclude that foreign gas rebreathing can provide reasonable Q(c) estimates with fewer repeat trials during resting conditions. During exercise, these methods remain precise but tend to underestimate Q(c). Single-step CO(2) rebreathing may be successfully employed over a wider range but with more measurements needed to overcome the larger variability. PMID:17556490

Jarvis, S S; Levine, B D; Prisk, G K; Shykoff, B E; Elliott, A R; Rosow, E; Blomqvist, C G; Pawelczyk, J A

2007-06-07

166

Pulse Wave Velocity and Cardiac Output vs. Heart Rate in Patients with an Implanted Pacemaker Based on Electric Impedance Method Measurement  

NASA Astrophysics Data System (ADS)

The methods and device for estimation of cardiac output and measurement of pulse wave velocity simultaneously is presented here. The beat-to-beat cardiac output as well as pulse wave velocity measurement is based on application of electrical impedance method on the thorax and calf. The results are demonstrated in a study of 24 subjects. The dependence of pulse wave velocity and cardiac output on heart rate during rest in patients with an implanted pacemaker was evaluated. The heart rate was changed by pacemaker programming while neither exercise nor drugs were applied. The most important result is that the pulse wave velocity, cardiac output and blood pressure do not depend significantly on heart rate, while the stroke volume is reciprocal proportionally to the heart rate.

Soukup, Ladislav; Vondra, Vlastimil; Viš?or, Ivo; Jurák, Pavel; Halámek, Josef

2013-04-01

167

Validation of the use of foreign gas rebreathing method for non-invasive determination of cardiac output in heart disease patients  

PubMed Central

Objective: To compare a new device (Innocor) for non-invasive measurement of cardiac output (CO) by foreign gas rebreathing method with conventional techniques used in the measurements of cardiac function. Methods: Cardiac outputs measured by Innocor (CORB) were compared with CO obtained by echocardiography (COEC), Swan-Ganz thermodilution (COTD), and left ventricle radiography (COLVR) in 34 patients subjected to cardiac catheterization. Values obtained from the four methods were analyzed by linear regression and paired values were compared by the method of Bland and Altman in SPSS. Results: There was strong positive correlation (r=0.94) between Innocor cardiac output values and the corresponding values obtained by thermodilution and between COEC and COLVR values. Thermodilution appears to overestimate cardiac output when compared to the values obtained with Innocor by (0.66±0.22) L/min (P<0.0001). There was no correlation between data obtained by Innocor and the corresponding COEC and COLVR values. Conclusion: Innocor CORB is an easy, safe and well established method for non-invasive measurement of cardiac output with good prospects for clinical application in heart disease patients.

Dong, Liang; Wang, Jian-an; Jiang, Chen-yang

2005-01-01

168

Gated single photon emission tomography MIBI stress perfusion imaging for assessing cardiac output and index in obese and non-obese patients  

Microsoft Academic Search

Objective To compare cardiac index, (CI) [i.e. Cardiac output (CO) corrected for body surface area], stroke volume index (SVI) and left ventricular ejection fraction (LVEF) of obese and non obese patients using gated Gated Single Photon Emission Computed Tomography (SPECT) MIBI perfusion imaging. This was done in order to assess haemodynamic function, represented by CI and systolic function represented by

J. P. Coffey; J. C. Hill

2007-01-01

169

Reduced central blood volume and cardiac output and increased vascular resistance during static handgrip exercise in postural tachycardia syndrome.  

PubMed

Postural tachycardia syndrome (POTS) is characterized by exercise intolerance and sympathoactivation. To examine whether abnormal cardiac output and central blood volume changes occur during exercise in POTS, we studied 29 patients with POTS (17-29 yr) and 12 healthy subjects (18-27 yr) using impedance and venous occlusion plethysmography to assess regional blood volumes and flows during supine static handgrip to evoke the exercise pressor reflex. POTS was subgrouped into normal and low-flow groups based on calf blood flow. We examined autonomic effects with variability techniques. During handgrip, systolic blood pressure increased from 112 +/- 4 to 139 +/- 9 mmHg in control, from 119 +/- 6 to 143 +/- 9 in normal-flow POTS, but only from 117 +/- 4 to 128 +/- 6 in low-flow POTS. Heart rate increased from 63 +/- 6 to 82 +/- 4 beats/min in control, 76 +/- 3 to 92 +/- 6 beats/min in normal-flow POTS, and 88 +/- 4 to 100 +/- 6 beats/min in low-flow POTS. Heart rate variability and coherence markedly decreased in low-flow POTS, indicating uncoupling of baroreflex heart rate regulation. The increase in central blood volume with handgrip was absent in low-flow POTS and blunted in normal-flow POTS associated with abnormal splanchnic emptying. Cardiac output increased in control, was unchanged in low-flow POTS, and was attenuated in normal-flow POTS. Total peripheral resistance was increased compared with control in all POTS. The exercise pressor reflex was attenuated in low-flow POTS. While increased cardiac output and central blood volume characterizes controls, increased peripheral resistance with blunted or eliminated in central blood volume increments characterizes POTS and may contribute to exercise intolerance. PMID:17616747

Stewart, Julian M; Taneja, Indu; Medow, Marvin S

2007-07-06

170

Cardiothoracic Anesthesia, Respiration and Airway Cardiac output by PulseCO ™ is not interchangeable with thermodilution in patients undergoing OPCAB  

Microsoft Academic Search

Purpose  To investigate the reliability of cardiac output assessed by arterial pressure waveform (PulseCO™) in comparison with bolus thermodilution measurements in patients undergoing off-pump coronary artery bypass grafting (OPCAB).\\u000a \\u000a \\u000a \\u000a Methods  23 patients who underwent OPCAB were enrolled in this study. After premedication with oral diazepam 10 mg, anesthesia was\\u000a induced with midazolam, fentanyl and vecuronium. After induction, radial artery and pulmonary artery

Koichi Yamashita; Tomoki Nishiyama; Takeshi Yokoyama; Hidehiro Abe; Masanobu Manabe

2005-01-01

171

Non-invasive beat-to-beat cardiac output monitoring by an improved method of transthoracic bioimpedance measurement.  

PubMed

The report describes a method of impedance cardiography using an improved estimate of thoracic volume. The formulas and their implementation in hardware and software are explained and new shortband electrodes are described which generate a good homogeneous thoracic field. Examples of stroke volume and cardiac output curves underline the capabilities of the monitoring system "Task Force Monitor". In several experiments, results are compared to thermodilution as well as to BioZ measurements: the new method excels in comparison with thermodilution and is comparable to the BioZ device. Compared to traditional electrodes, the new shortband electrodes are shown to provide better reproducibility. PMID:16131462

Fortin, J; Habenbacher, W; Heller, A; Hacker, A; Grüllenberger, R; Innerhofer, J; Passath, H; Wagner, Ch; Haitchi, G; Flotzinger, D; Pacher, R; Wach, P

2005-08-29

172

Influence of water immersion, water gymnastics and swimming on cardiac output in patients with heart failure  

Microsoft Academic Search

Background: Whole-body water immersion leads to a significant shift of blood from the periphery to the intrathoracic circulation, followed by an increase in central venous pressure and heart volume. In patients with severely reduced left ventricular function, this hydrostatically induced volume shift might overstrain the cardiovascular adaptive mechanisms and lead to cardiac decompensation.Aim: To assess the haemodynamic response to water

Jean-Paul Schmid; Markus Noveanu; Cyrill Morger; Raymond Gaillet; Mauro Capoferri; Matthias Anderegg; Hugo Saner

2007-01-01

173

Regional blood flow in chronic heart failure: the reason for the lack of correlation between patients' exercise tolerance and cardiac output?  

PubMed Central

BACKGROUND--In patients with chronic heart failure there is no relation between cardiac output and symptom limited exercise tolerance measured on a bicycle or treadmill. Furthermore, the increase in cardiac output in response to treatment may not be matched by a similar increase in exercise tolerance. More important in determining exercise capability is blood flow to skeletal muscle. This implies that the reduction in skeletal muscle blood flow is not directly proportional to the reduction in cardiac output and that there are regional differences in blood flow in patients with heart failure. METHODS--Cardiac output and regional blood flow measured in 30 patients with chronic heart failure were compared with values obtained from 10 healthy controls. Measurements were made at rest and in response to treadmill exercise and were all made non-invasively. RESULTS--Cardiac output was lower in the patients at rest and during exercise. Blood flow in the superior mesenteric and renal arteries was also lower in the patients and represented a different proportion of cardiac output than in the controls. In response to exercise the increase in blood flow to the calf and therefore to skeletal muscle, was reduced in the patients. In the patients there was no correlation between resting cardiac output and blood flow in the superior mesenteric artery, renal artery, or calf. CONCLUSIONS--Because blood flow to skeletal muscle and to the kidneys is likely to be important in determining patients' symptoms this factor may explain why central haemodynamic variables do not correlate with the exercise tolerance in patients with chronic heart failure.

Muller, A F; Batin, P; Evans, S; Hawkins, M; Cowley, A J

1992-01-01

174

[Applicability of the two-compartment coaxial cylindrical model for ambulatory measuring of cardiac output with spot-electrodes].  

PubMed

The principle of ambulatory cardiac output (CO) measuring technique is introduced in this paper. Experimental studies about the applicability of the two-compartment coaxial cylindrical model for ambulatory measurement of cardiac output with spot-electrodes have been carried out with using our newly-developed multi-channel impedance mapping system. The key factors using a spot-electrode array instead of a conventional band-electrode array for non-invasive CO) measurement are elaborated. The variations of the electric impedance pulsatile component (deltaZ waveform) and the two kinds of typical modes of deltaZ distributions measured by six electrodes on the midsternal (midian) line from the medial portion at the level of clavicle to the portion above the xiphisternum are discussed. The applicability of the two-compartment coaxial cylindrical model for ambulatory measurement of CO with spot-electrodes is analyzed. Synthesizing the deltaZ distributions and their typical changing models on the midsternal (midian) line during blood inflowing into aorta is the optimal positions of a pair of spot-electrodes for voltage pick-up at the level of clavicle for the upper electrode and the position at the level of nipple for the lower electrode when spot-electrode is being used to measure non-invasive CO. PMID:24059037

Song, Yilin; Gao, Shumei; Ikrashi, Akira; Yamakoshi, Ken-ichi

2013-08-01

175

Measurement of cardiac output from a test-bolus injection in multislice computed tomography  

Microsoft Academic Search

The aim of this study was to assess the feasibility of non-invasive determination of cardiac function from test-bolus data in multislice spiral computed tomography (MSCT). In 25 patients enhancement data gathered from a standardized test-bolus injection were analyzed. The test-bolus examination was performed prior to a retrospectively ECG-gated MSCT of the heart. A time–attenuation curve was obtained in the ascending

Andreas H. Mahnken; Ernst Klotz; Anja Hennemuth; Bettina Jung; Ralf Koos; Joachim E. Wildberger; Rolf W. Günther

2003-01-01

176

Self-calibrating pulse contour cardiac output: do validation studies really show its clinical reliability?  

Microsoft Academic Search

The present study was performed to test a new software version of the FloTrac\\/Vigileo using head-up–head-down tilting in post-cardiac\\u000a surgery patients. Impressive improvements in Bland and Altman limits of agreement from 37.5% to 21.6% were recorded. The results,\\u000a however could be attributed to a failure to produce a wide enough range of test circulatory conditions. A more rigorous test\\u000a of

Lester AH Critchley; Intensive Care

2009-01-01

177

Training is required to improve the reliability of esophageal doppler to measure cardiac output in critically ill patients  

Microsoft Academic Search

Objectives: Assessment of and effect of training on reliability of esophageal Doppler (ED) versus thermodilution (TD) for cardiac output\\u000a (CO) measurement.\\u000a \\u000a \\u000a Design: Prospective study.\\u000a \\u000a \\u000a \\u000a \\u000a Setting: Intensive care unit of a university hospital.\\u000a \\u000a \\u000a \\u000a \\u000a Patients: 64 consecutive critically ill patients requiring a pulmonary artery catheter, sedation, and mechanical ventilation.\\u000a \\u000a \\u000a \\u000a \\u000a Interventions: Esophageal Doppler CO measurements were performed by the same operator, whereas TD

J. Y. Lefrant; P. Bruelle; A. G. M. Aya; G. Saïssi; M. Dauzat; J. E. de La Coussaye; J. J. Eledjam

1998-01-01

178

Rapid assessment of cardiac output and central blood volumes from indicator dilution curves without precalculation using programmable calculators.  

PubMed

The program described here provides complete analysis of the indicator dilution curve by incorporating densitometric calibration and logarithmic downslope fit for the widely used Hewlett-Packard 67/97 hand calculator series. Densitometric sensitivity is calculated from the linear regression as the dye calibration factor; thus, direct entry of the dye curve deflections eliminate the necessity to precalculate curve concentration. The program displays appropriate sequential time intervals prompting deflection entry of the upslope and initial exponential downslope of the curve. The remainder of the curve is generated from the logarithmically extrapolated initial downslope, and the area of the curve is then obtained for calculation of cardiac output, mean transit time, and central blood volume. Programming versatility and the rapid (4--5 min) immediate analysis of indicator dilution curves are thus available. PMID:6993093

Cole, M A; Crawford, D W

1980-04-01

179

Variations in arterial blood pressure are associated with parallel changes in FlowTrac/Vigileo®-derived cardiac output measurements: a prospective comparison study  

PubMed Central

Introduction The reliability of autocalibrated pressure waveform analysis by the FloTrac-Vigileo® (FTV) system for the determination of cardiac output in comparison with intermittent pulmonary arterial thermodilution (IPATD) is controversial. The present prospective comparison study was designed to determine the effects of variations in arterial blood pressure on the reliability of the FTV system in patients undergoing coronary artery bypass grafting (CABG). Methods Comparative measurements of cardiac output by FTV (derived from a femoral arterial line; software version 1.14) and IPATD were performed in 16 patients undergoing elective CABG in the period before institution of cardiopulmonary bypass. Measurements were performed after induction of anesthesia, after sternotomy, and during five time points during graft preparation. During graft preparation, arterial blood pressure was increased stepwise in intervals of 10 to 15 minutes by infusion of noradrenaline and lowered thereafter to baseline levels. Results Mean arterial blood pressure was varied between 85 mmHg and 115 mmHg. IPATD cardiac output did not show significant changes during periods with increased arterial pressure either during sternotomy or after pharmacological manipulation. In contrast, FTV cardiac output paralleled changes in arterial blood pressure; i.e. increased significantly if blood pressure was raised and decreased upon return to baseline levels. Mean arterial blood pressure (MAP) and FTV cardiac output were closely correlated (r = 0.63 (95% confidence interval [CI]: 0.49 - 0.74), P < 0.0001) while no correlation between MAP and IPATD cardiac output was observed. Bland-Altman analyses for FTV versus IPATD cardiac output measurements revealed a bias of 0.4 l/min (8.5%) and limits of agreement from 2.1 to -1.3 l/min (42.2 to -25.3%). Conclusions Acute variations in arterial blood pressure alter the reliability of the FlowTrac/Vigileo® device with the second-generation software. This finding may help to explain the variable results of studies comparing the FTV system with other cardiac output monitoring techniques, questions the usefulness of this device for hemodynamic monitoring of patients undergoing rapid changes in arterial blood pressure, and should be kept in mind when using vasopressors during FTV-guided hemodynamic optimization.

2009-01-01

180

[Clinical practice guide for the management of low cardiac output syndrome in the postoperative period of heart surgery].  

PubMed

The low cardiac output syndrome is a potential complication in cardiac surgery patients and associated with increased morbidity and mortality. This guide is to provide recommendations for the management of these patients, immediately after surgery, admitted to the ICU. The recommendations are grouped into different sections, trying to answer from the most basic concepts such as the definition to the different sections of basic and advanced monitoring and ending with the complex management of this syndrome. We propose an algorithm for initial management, as well as two other for ventricular failure (predominantly left or right). Most of the recommendations are based on expert consensus because of the lack of randomized trials of adequate design and sample size in this group of patients. The quality of evidence and strength of the recommendations were made following the GRADE methodology. The guide is presented as a list of recommendations (and level of evidence for each recommendation) for each question on the selected topic. Then for each question, we proceed to the justification of the recommendations. PMID:22445905

Pérez Vela, J L; Martín Benítez, J C; Carrasco González, M; de la Cal López, M A; Hinojosa Pérez, R; Sagredo Meneses, V; del Nogal Saez, F

2012-03-23

181

Arterial pressure-based cardiac output in septic patients: different accuracy of pulse contour and uncalibrated pressure waveform devices  

PubMed Central

Introduction We compared the ability of two devices estimating cardiac output from arterial pressure-curve analysis to track the changes in cardiac output measured with transpulmonary thermodilution induced by volume expansion and norepinephrine in sepsis patients. Methods In 80 patients with septic circulatory failure, we administered volume expansion (40 patients) or introduced/increased norepinephrine (40 patients). We measured the pulse contour-derived cardiac index (CI) provided by the PiCCO device (CIpc), the arterial pressure waveform-derived CI provided by the Vigileo device (CIpw), and the transpulmonary thermodilution CI (CItd) before and after therapeutic interventions. Results The changes in CIpc accurately tracked the changes in CItd induced by volume expansion (bias, -0.20 ± 0.63 L/min/m2) as well as by norepinephrine (bias, -0.05 ± 0.74 L/min/m2). The changes in CIpc accurately detected an increase in CItd ? 15% induced by volume expansion and norepinephrine introduction/increase (area under ROC curves, 0.878 (0.736 to 0.960) and 0.924 (0.795 to 0.983), respectively; P < 0.05 versus 0.500 for both). The changes in CIpw were less reliable for tracking the volume-induced changes in CItd (bias, -0.23 ± 0.95 L/min/m2) and norepinephrine-induced changes in CItd (bias, -0.01 ± 1.75 L/min/m2). The changes in CIpw were unable to detect an increase in CItd ? 15% induced by volume expansion and norepinephrine introduction/increase (area under ROC curves, 0.564 (0.398 to 0.720) and 0.541 (0.377 to 0.700, respectively, both not significantly different from versus 0.500). Conclusions The CIpc was reliable and accurate for assessing the CI changes induced by volume expansion and norepinephrine. By contrast, the CIpw poorly tracked the trends in CI induced by those therapeutic interventions.

2010-01-01

182

A fMRI Study of Verbal Working Memory, Cardiac Output, and Ejection Fraction in Elderly Patients with Cardiovascular Disease  

PubMed Central

Cardiovascular disease (CVD) is associated with cognitive deficits even in the absence of stroke. We examined the relationship between cardiac performance, as measured by cardiac output (CO) and ejection fraction (EF), and brain activity during a verbal working memory (VWM) task in elderly CVD patients who tend to be at increased risk for vascular cognitive impairments. Seventeen patients were recruited from a cohort participating in an ongoing prospective study examining the effects of CVD on cognitive function in the elderly. Participants were diagnosed with CVD (age 68±8) and completed a 2-back VWM task in a 1.5T fMRI paradigm. CO and EF were calculated from echocardiogram measures. Task-related activation was averaged in a priori regions of interest. The relationship between CO, EF, and 2-back-related activity was modeled using partial correlations (two-tailed p<.05) controlling for age and 2-back accuracy. All participants were globally cognitively intact as indicated by Mini-Mental Status Exam and Dementia Rating Scale scores. Mean accuracy on the 2-back was 78±9% while reaction time averaged 1,027±192 ms. Mean CO and EF values showed a large range (CO: 3.55 to 6.31; EF: 0.36 to 0.76) but average values were within the normal range. After controlling for age and 2-back accuracy, lower EF was related to decrease in left insula activity (r=0.61, p=0.03). There were trends for EF to be related to accuracy (r=0.47, p=0.09) and reaction time (r=?0.48, p=0.09). CO was also related to insula activity (r=0.60, p=0.04) and activity in the supplementary motor area activity (r=0.66, p=0.01). Cardiac performance was related to decreased efficiency in task related brain areas and tended to be related to performance on a VWM task in elderly patients with CVD. Results have implications for a line of investigation indicating that cardiac and systemic vascular indices could be used as proxy measures to examine mechanisms of cerebrovascular dysfunction in the elderly.

Irani, Farzin; Haley, Andreana P.; Gunstad, John J.; Jerskey, Beth A.; Mulligan, Richard C.; Jefferson, Angela L.; Poppas, Athena; Cohen, Ronald A.

2011-01-01

183

Cardiac output monitoring in septic shock: evaluation of the third-generation Flotrac-Vigileo.  

PubMed

Continuous cardiac index (CI) monitoring is frequently used in critically ill patients. Few studies have compared the pulse contour-based device FloTrac/Vigileo to pulmonary artery thermodilution (PAC) in terms of accuracy for CI monitoring in septic shock. The aim of our study was to compare the third-generation FloTrac/Vigileo to PAC in septic shock. Eighteen patients with septic shock requiring monitoring by PAC were included in this study. We monitored CI using both FloTrac/Vigileo and continuous thermodilution (PAC-CI). Hemodynamic data were recorded every hour or every 2 min during fluid challenges. The primary endpoint was the global agreement of all CI-paired measurements determined using the Bland-Altman method adapted to replicated data. We tested the linearity of the bias by regression analysis, and compared the reactivity of the 2 techniques during fluid challenges. A receiver operating characteristic (ROC) curve analysis tested the ability of FloTrac/Vigileo to detect concordant and significative CI changes, using PAC-CI as the reference method. Overall, 1,201 paired CI measurements were recorded. The Bland-Altman analysis for global agreement of the 2 techniques showed a bias of -0.1 ± 2.1 L min(-1) m(-2) and a percentage error of 64 %. The overall correlation coefficient between PAC-CI and FloTrac/Vigileo CI was 0.47 (p < 0.01), with r(2) = 0.22. The area under the curve of the ROC curve for detecting concordant and significant changes in CI was 0.72 (0.53; 0.87). In our study, third-generation Flowtrac-Vigileo appears to be too inaccurate to be recommended for CI monitoring in septic shock. PMID:23361128

Marqué, Sophie; Gros, Antoine; Chimot, Loic; Gacouin, Arnaud; Lavoué, Sylvain; Camus, Christophe; Le Tulzo, Yves

2013-01-30

184

Cardiac output by Doppler echocardiography in the premature baboon: Comparison with radiolabeled microspheres  

SciTech Connect

Pulsed-Doppler echocardiography (PDE) is a useful noninvasive method for determining left ventricular output (LVO). However, despite increasingly widespread use in neonatal intensive care units, validation studies in prematures with cardiopulmonary disease are lacking. The purpose of this study was to compare radiolabeled microsphere (RLM) and PDE measurements of LVO, using the critically ill premature baboon as a model of the human neonate. Twenty-two paired RLM and PDE measurements of LVO were obtained in 14 animals between 3 and 24 h of age. Average PDE LVO was 152 ml/min/kg (range, 40-258 ml/min/kg) compared to 158 ml/min/kg (range, 67-278 ml/min/kg) measured by RLM. Linear regression analysis of the paired measurements showed good correlation with a slope near unity (gamma = 0.94x + 4.20, r = 0.91, SEE = 25.7 ml). The authors conclude that PDE determinations of LVO compare well with those measured by RLM in the premature baboon. PDE appears to provide a valid estimate of LVO and should be useful in human prematures with cardiopulmonary distress.

Kinsella, J.P.; Morrow, W.R.; Gerstmann, D.R.; Taylor, A.F.; deLemos, R.A. (Wilford Hall U.S.A.F. Medical Center, San Antonio, TX (USA))

1991-04-01

185

Bench-to-bedside review: The importance of the precision of the reference technique in method comparison studies – with specific reference to the measurement of cardiac output  

Microsoft Academic Search

Bland-Altman analysis is used for assessing agreement between two measurements of the same clinical variable. In the field of cardiac output monitoring, its results, in terms of bias and limits of agreement, are often difficult to interpret, leading clinicians to use a cutoff of 30% in the percentage error in order to decide whether a new technique may be considered

Maurizio Cecconi; Andrew Rhodes; Jan Poloniecki; Giorgio Della Rocca; R Michael Grounds

2009-01-01

186

Comparison of impedance cardiography with thermodilution and direct fick methods for noninvasive measurement of stroke volume and cardiac output during incremental exercise in patients with ischemic cardiomyopathy  

Microsoft Academic Search

In the last decade, an inexpensive and simple noninvasive method (i.e., transthoracic electrical bioimpedance cardiography, has been tested in healthy subjects and patients with various heart diseases for measuring stroke volume and cardiac output at rest and\\/or during exercise. However, the results are still controversial, especially when measurements are obtained during exercise and data on reproducibility during exercise are lacking.

Romualdo Belardinelli; Nino Ciampani; Carlo Costantini; Alfonso Blandini; Augusto Purcaro

1996-01-01

187

Acute effects of muscular counterpulsation therapy on cardiac output and safety in patients with chronic heart failure.  

PubMed

Our aim was to investigate acute effects of muscular counterpulsation (MCP) on hemodynamic parameters and to evaluate its safety in regard to myocardial integrity and interferences with implanted rhythm devices in patients with chronic heart failure (CHF). A total of 22 patients with CHF (16 male, 67.8?±?9.5 years, New York Heart Association [NYHA] class II?+?III, left ventricular ejection fraction 29.6?±?6.6%) were treated with MCP for 3 consecutive days for 45?min, while hemodynamic parameters were measured noninvasively by bioimpedance (Task Force Monitor). Laboratory control and a complete device testing were performed prior to the first and after the third treatment. In addition, continuous rhythm device interrogation was performed online during the first MCP application. During each application, a significant increase in cardiac output (CO; average change +2.08?±?2.33?L/min, P?Cardiac markers and enzymes were within normal limits at all times and did not increase during treatment. MCP stimuli were monitored using surface electrocardiogram, and no abnormal sensing or pacing events occurred. MCP acutely improves CO in patients with stable CHF. No adverse influence on myocardial integrity was observed nor were any inappropriate sensing or pacing artifacts detected in patients with implanted rhythm devices. PMID:22145938

Ostojic, Dominique; Seifert, Ingmar; Pütz, Vanessa; Bartsch, Stephan; Bitter, Thomas; Horstkotte, Dieter; Oldenburg, Olaf

2011-12-06

188

Uncalibrated pulse power analysis fails to reliably measure cardiac output in patients undergoing coronary artery bypass surgery  

PubMed Central

Introduction Uncalibrated arterial pulse power analysis has been recently introduced for continuous monitoring of cardiac index (CI). The aim of the present study was to compare the accuracy of arterial pulse power analysis with intermittent transpulmonary thermodilution (TPTD) before and after cardiopulmonary bypass (CPB). Methods Forty-two patients scheduled for elective coronary surgery were studied after induction of anaesthesia, before and after CPB respectively. Each patient was monitored with the pulse contour cardiac output (PiCCO) system, a central venous line and the recently introduced LiDCO monitoring system. Haemodynamic variables included measurement of CI derived by transpulmonary thermodilution (CITPTD) or CI derived by pulse power analysis (CIPP), before and after calibration (CIPPnon-cal., CIPPcal.). Percentage changes of CI (?CITPTD, ?CIPPnon-cal./PPcal.) were calculated to analyse directional changes. Results Before CPB there was no significant correlation between CIPPnon-cal. and CITPTD (r2 = 0.04, P = 0.08) with a percentage error (PE) of 86%. Higher mean arterial pressure (MAP) values were significantly correlated with higher CIPPnon-cal. (r2 = 0.26, P < 0.0001). After CPB, CIPPcal. revealed a significant correlation compared with CITPTD (r2 = 0.77, P < 0.0001) with PE of 28%. Changes in CIPPcal. (?CIPPcal.) showed a correlation with changes in CITPTD (?CITPTD) only after CPB (r2 = 0.52, P = 0.005). Conclusions Uncalibrated pulse power analysis was significantly influenced by MAP and was not able to reliably measure CI compared with TPTD. Calibration improved accuracy, but pulse power analysis was still not consistently interchangeable with TPTD. Only calibrated pulse power analysis was able to reliably track haemodynamic changes and trends.

2011-01-01

189

Roles for Cardiac MyBP-C in Maintaining Myofilament Lattice Rigidity and Prolonging Myosin Cross-Bridge Lifetime  

SciTech Connect

We investigated the influence of cardiac myosin binding protein-C (cMyBP-C) and its constitutively unphosphorylated status on the radial and longitudinal stiffnesses of the myofilament lattice in chemically skinned myocardial strips of the following mouse models: nontransgenic (NTG), effective null for cMyBP-C (t/t), wild-type cMyBP-C expressed into t/t (WT{sub t/t}), and constitutively unphosphorylated cMyBP-C (AllP{sub -t/t}). We found that the absence of cMyBP-C in the t/t and the unphosphorylated cMyBP-C in the AllP{sub -t/t} resulted in a compressible cardiac myofilament lattice induced by rigor not observed in the NTG and WT{sub t/t}. These results suggest that the presence and phosphorylation of the N-terminus of cMyBP-C provides structural support and radial rigidity to the myofilament lattice. Examination of myofilament longitudinal stiffness under rigor conditions demonstrated a significant reduction in cross-bridge-dependent stiffness in the t/t compared with NTG controls, but not in the AllP{sub -t/t} compared with WT{sub t/t} controls. The absence of cMyBP-C in the t/t and the unphosphorylated cMyBP-C in the AllP{sub -t/t} both resulted in a shorter myosin cross-bridge lifetime when myosin isoform was controlled. These data collectively suggest that cMyBP-C provides radial rigidity to the myofilament lattice through the N-terminus, and that disruption of the phosphorylation of cMyBP-C is sufficient to abolish this structural role of the N-terminus and shorten cross-bridge lifetime. Although the presence of cMyBP-C also provides longitudinal rigidity, phosphorylation of the N-terminus is not necessary to maintain longitudinal rigidity of the lattice, in contrast to radial rigidity.

Palmer, B.M.; Sadayappan, S.; Wang, Y.; Weith, A.E.; Previs, M.J.; Bekyarova, T.; Irving, T.C.; Robbins, J.; Maughan, D.W. (Vermont)

2011-10-06

190

Comparison of cardiac output of the left and right side of the heart by ultrafast computed tomography  

SciTech Connect

Ultrafast computed tomography (CT) evaluation of cardiac output (CO) can be determined using indicator dilution theory. The concentration of an iodinated contrast agent injected into a vein of a subject can be measured as a function of time by serial EKG, gated CT imaging. The contrast density of the blood pool measured by CT defines the indicator concentration. CT CO is proportional to the area under a time density curve from a region of the blood pool. Proper subject position and scanning timing allows CT to measure CO in the pulmonary (PA) artery and the aorta (AO) with the same contrast bolus. Three anesthetized dogs were multiply scanned following simultaneous injections of contrast and radioactive tracer microspheres. Microsphere CO was determined by reference withdrawal method. Multiple thermodilution CO measurements were made just prior and after each CT CO procedure. 24 comparisons were made of thermodilution, microsphere and CT CO measured in the PA (right sided CO (RSCO)) and the AO (left sided CO (LSCO)). CT CO was calculated as the ratio of the volume of contrast injected to the time density curve area corrected for the relation of contrast density to CT number. RSCO agreed very closely to LSCO (r = .99, p < .001; y = 1.0x +/- .32). RSCO correlated to thermodilution (r = .96, p < .001; y = 1.2x +/- 1.3) and microsphere CO (r = .93, p < .001; y = .69x +/- 1.3). These data show that CT CO measurements can be made in the PA and AO with equal accuracy.

Wolfkiel, C.J.; Ferguson, J.L.; Law, W.R.; Chomka, E.V.; Brundage, B.H.

1986-03-05

191

Nimodipine has no effect on the cerebral circulation in conscious pigs, despite an increase in cardiac output.  

PubMed Central

1. We studied the effects of four doses of nimodipine (0.5, 1, 2 and 4 micrograms kg-1 min-1) on systemic haemodynamics and on regional vascular beds, in particular the cerebral circulation, in conscious pigs. 2. Nimodipine caused dose-dependent, probably reflex-mediated, increases in heart rate (42% with the highest dose) and cardiac output (54%), while arterial blood pressure was only minimally affected. Left ventricular end-diastolic pressure and systemic vascular resistance decreased dose-dependently (35-40% at the highest dose) while stroke volume remained unchanged. 3. Total brain blood flow was not affected by the drug. Furthermore, we could not demonstrate any regional cerebral differences, as blood flows to both cerebral hemispheres as well as the diencephalon, cerebellum and brain stem remained unchanged. 4. Blood flow to the kidneys, liver, small intestine and skin also did not change. Nimodipine caused dose-dependent increases in blood flow to the stomach (95%), myocardium (97%) and adrenal glands (102%), while blood flow to skeletal muscles (267%) increased most. 5. It is concluded that in the conscious pig, nimodipine is an arterial vasodilator which shows some selectivity for the skeletal muscle vasculature but does not increase total or regional cerebral blood flow.

van der Giessen, W. J.; Duncker, D. J.; Saxena, P. R.; Verdouw, P. D.

1990-01-01

192

Noninvasive measurement of cardiac output in hemodialysis patients by task force monitor: a comparison with the Transonic System.  

PubMed

Cardiovascular disease is the leading cause of morbidity and mortality in maintenance hemodialysis (MHD) patients. The Transonic (TRS; Transonic Systems, Ithaca, NY) device is frequently used for determination of cardiac output (CO) by an indicator dilution technique. The Task Force Monitor (TFM; CN Systems, Graz, Austria) has gained attention as noninvasive tool for continuous beat-to-beat assessment of cardiovascular variables, including CO by impedance cardiography. Despite its use in cardiology and intensive care settings, the TFM has yet not been validated in dialysis patients. This study compares CO measurements in 12 MHD patients by TFM and TRS. Bland-Altman and regression analysis were used. CO was measured simultaneously by TRS and TFM. Average CO was 5.4 L/min by TRS and 5.0 L/min by TFM, respectively. Bland-Altman analysis revealed no significant systematic differences between the two methods (mean difference: 0.4 L/min; SD: 0.6; p > 0.05). Linear regression analysis showed significant correlation between both techniques (r = 0.802, p = 0.002). The SD of mean individual CO values was 1.1 L/min with TRS and 0.8 L/min with TFM, respectively.CO measured by TFM and TRS does not differ significantly, thus making the TFM an attractive noninvasive tool for the continuous beat-to-beat assessment of CO in MHD patients. PMID:17885328

Kitzler, Thomas M; Sergeyeva, Olga; Morris, Alice; Skrabal, Falko; Kotanko, Peter; Levin, Nathan W

193

Accuracy of cardiac output measurements during off-pump coronary artery bypass grafting: according to the vessel anastomosis sites  

PubMed Central

Background During beating heart surgery, the accuracy of cardiac output (CO) measurement techniques may be influenced by several factors. This study was conducted to analyze the clinical agreement among stat CO mode (SCO), continuous CO mode (CCO), arterial pressure waveform-based CO estimation (APCO), and transesophageal Doppler ultrasound technique (UCCO) according to the vessel anastomosis sites. Methods This study was prospectively performed in 25 patients who would be undergoing elective OPCAB. Hemodynamic variables were recorded at the following time points: during left anterior descending (LAD) anastomosis at 1 min and 5 min; during obtuse marginal (OM) anastomosis at 1 min and 5 min: and during right coronary artery (RCA) anastomosis at 1 min and 5 min. The variables measured including the SCO, CCO, APCO, and UCCO. Results CO measurement techniques showed different correlations according to vessel anastomosis site. However, the percent error observed was higher than the value of 30% postulated by the criteria of Critchley and Critchley during all study periods for all CO measurement techniques. Conclusions In the beating heart procedure, SCO, CCO and APCO showed different correlations according to the vessel anastomosis sites and did not agree with UCCO. CO values from the various measurement techniques should be interpreted with caution during OPCAB.

Park, Sung Yong; Kim, Dae Hee; Joe, Han Bum; Yoo, Ji Young; Kim, Jin Soo; Kang, Min

2012-01-01

194

Validation of Cardiac Output Measurement by Ultrasound Dilution Technique With Pulmonary Artery Thermodilution in a Pediatric Animal Model  

PubMed Central

Novel COstatus system (Transonic Systems, Inc., NY), based on ultrasound dilution (UD), works off in situ arterial and central venous catheters in pediatric patients to measure cardiac output (CO). The purpose of the present study was to validate CO measurement by UD (COUD) with pulmonary artery (PA) thermodilution (COTD) in a prospective animal study. Ten anesthetized pigs (16–45 kg) were instrumented with pediatric PA, central venous, and peripheral artery catheters. For COUD measurements, normothermic saline (0.5–1.0 ml/kg body weight, up to a maximum of 30 ml) was injected into the venous limb of an arteriovenous loop that was connected between in situ catheters. For COTD measurements, 5–10 ml cold saline was injected into the PA catheter. Sixty-four averaged sets were obtained for comparison. COTD mean was 2.98 ± 1.21 l/min (range 1.33–6.29), and COUD mean was 2.68 ± 1.16 l/min (range 1.33–5.85). This study yielded a correlation r = 0.96, COUD = 0.91* (COTD) ? 0.04 l/min; bias was 0.3 l/min with limits of agreement as ?0.39 to 0.99 l/min; and the percentage error was 23.73% between the methods. CO measurements by UD agreed well with thermodilution measurements in the pediatric swine model.

Thuramalla, Naveen; Searles, Bruce

2011-01-01

195

[Clinical Evaluation of Intraoperative Cardiac Output Measurement by a New Arterial Pressure Waveform Analysis Method( FloTrac/Vigileo) in Open Heart Surgery].  

PubMed

We retrospectively evaluated the initial clinical experience of intraoperative cardiac output measurement by a new arterial pressure-based cardiac output (APCO:FloTrac/Vigileo) analysis in patients undergoing open heart surgery. Thirty-two patients (mean age 76.4, range 59 to 90)who underwent cardiac surgery under cardiopulmonary bypass( CPB) from July 2008 to September 2009 in our institute were enrolled in this study. There were 14 women and 18 men. The cardiac operations included 28 valve surgeries and 4 coronary artery bypass grafting. The APCO was introduced initially, then a continuous cardiac output (CCO:Swan-Ganz catheter) analysis system was established following the induction of anesthesia. The correlation of both cardiac output measurements was evaluated at 5 time points, T1:induction of anesthesia, T2:sternotomy, T3:after weaning from CPB, T4:closure of the chest, and T5:arrival at intensive care unit. There were no serious complications related to APCO and CCO. The correlation between APCO and CCO was evaluated by Bland-Altman plot analysis. The percentages of correlation between both groups were T1:81.2%, T2:78.1%, T3:59.4%, T4:62.5%, and T5:65.6%. A good correlation was shown in all 6 patients with atrial fibrillation at T1 and T2. No correlation was shown in the 3 patients with left ventricular( LV) dysfunction below LVEF 40%, 1 case at T3, all 3 cases at T4, and 2 cases at T5. Before the institution of CPB, 3 of the 6 at T1 and 3 of the 7 at T2 in whom no correlation was shown, had severe aortic valve insufficiency (AVI).From these results, APCO appears to be an acceptable device to evaluate the intraoperative cardiac output measurement compared with CCO, except in patients with LV dysfunction or AVI at some time points. Further studies will be necessary to elucidate the precise clinical evidence to assess the efficacy of this new analysis device. PMID:23917227

Furukawa, Hiroshi; Ohkado, Akihiko; Nagashima, Mitsugi; Ohsawa, Hiroshi; Ichikawa, Sei-Ichi

2013-08-01

196

Arterial pressure-based cardiac output monitoring: a multicenter validation of the third-generation software in septic patients  

PubMed Central

Purpose Second-generation FloTrac software has been shown to reliably measure cardiac output (CO) in cardiac surgical patients. However, concerns have been raised regarding its accuracy in vasoplegic states. The aim of the present multicenter study was to investigate the accuracy of the third-generation software in patients with sepsis, particularly when total systemic vascular resistance (TSVR) is low. Methods Fifty-eight septic patients were included in this prospective observational study in four university-affiliated ICUs. Reference CO was measured by bolus pulmonary thermodilution (iCO) using 3–5 cold saline boluses. Simultaneously, CO was computed from the arterial pressure curve recorded on a computer using the second-generation (COG2) and third-generation (COG3) FloTrac software. CO was also measured by semi-continuous pulmonary thermodilution (CCO). Results A total of 401 simultaneous measurements of iCO, COG2, COG3, and CCO were recorded. The mean (95%CI) biases between COG2 and iCO, COG3 and iCO, and CCO and iCO were ?10 (?15 to ?5)% [?0.8 (?1.1 to ?0.4) L/min], 0 (?4 to 4)% [0 (?0.3 to 0.3) L/min], and 9 (6–13)% [0.7 (0.5–1.0) L/min], respectively. The percentage errors were 29 (20–37)% for COG2, 30 (24–37)% for COG3, and 28 (22–34)% for CCO. The difference between iCO and COG2 was significantly correlated with TSVR (r2 = 0.37, p < 0.0001). A very weak (r2 = 0.05) relationship was also observed for the difference between iCO and COG3. Conclusions In patients with sepsis, the third-generation FloTrac software is more accurate, as precise, and less influenced by TSVR than the second-generation software. Electronic supplementary material The online version of this article (doi:10.1007/s00134-010-2098-8) contains supplementary material, which is available to authorized users.

Marx, Gernot; Tan, Andrew; Junker, Christopher; Van Nuffelen, Marc; Huter, Lars; Ching, Willy; Michard, Frederic; Vincent, Jean-Louis

2010-01-01

197

G16R single nucleotide polymorphism but not haplotypes of the ?(2)-adrenergic receptor gene alters cardiac output in humans.  

PubMed

Variation in genes encoding the ?(2)-adrenergic receptor (ADRB2) and angiotensin-converting enzyme (ACE) may influence Q (cardiac output). The 46G>A (G16R) SNP (single nucleotide polymorphism) has been associated with ?(2)-mediated vasodilation, but the effect of ADRB2 haplotypes on Q has not been studied. Five SNPs within ADRB2 (46G>A, 79C>G, 491C>T, 523C>A and 1053G>C by a pairwise tagging principle) and the I/D (insertion/deletion) polymorphism in ACE were genotyped in 143 subjects. Cardiovascular variables were evaluated by the Model flow method at rest and during incremental cycling exercise. Only the G16R polymorphism was associated with Q. In carriers of the Arg(16) allele, Q(rest) (resting Q) was 0.4 [95% CI (confidence interval), 0.0-0.7] l/min lower than in G16G homozygotes (P=0.048). During exercise, the increase in Q was by 4.7 (95% CI, 4.3-5.2) l/min per litre increase in pulmonary Vo(2) (oxygen uptake) in G16G subjects, but the increase was 0.5 (0.0-0.9) l/min lower in Arg16 carriers (P=0.035). A similar effect size was observed for the Arg16 haplotypes ACCCG and ACCCC. No interaction was found between ADRB2 and ACE polymorphisms. During exercise, the increase in Q was 0.5 (CI, 0.0 -1.0) l/min greater in ACE I/I carriers compared with I/D and D/D subjects (P=0.054). In conclusion, the ADRB2 Arg16 allele in humans is associated with a lower Q both at rest and during exercise, overriding the effects of haplotypes. PMID:23438238

Rokamp, Kim Z; Staalsoe, Jonatan M; Gartmann, Martin; Sletgaard, Anna; Nordsborg, Nicolai B; Secher, Niels H; Nielsen, Henning B; Olsen, Niels V

2013-08-01

198

Dynamic cardiac output regulation at rest, during exercise, and muscle metaboreflex activation: impact of congestive heart failure  

PubMed Central

We tested whether mild and moderate dynamic exercise and muscle metaboreflex activation (MMA) affect dynamic baroreflex control of heart rate (HR) and cardiac output (CO), and the influence of stroke volume (SV) fluctuations on CO regulation in normal (N) and pacing-induced heart failure (HF) dogs by employing transfer function analyses of the relationships between spontaneous changes in left ventricular systolic pressure (LVSP) and HR, LVSP and CO, HR and CO, and SV and CO at low and high frequencies (Lo-F, 0.04–0.15 Hz; Hi-F, 0.15–0.6 Hz). In N dogs, both workloads significantly decreased the gains for LVSP-HR and LVSP-CO in Hi-F, whereas only moderate exercise also reduced the LVSP-CO gain in Lo-F. MMA during mild exercise further decreased the gains for LVSP-HR in both frequencies and for LVSP-CO in Lo-F. MMA during moderate exercise further reduced LVSP-HR gain in Lo-F. Coherence for HR-CO in Hi-F was decreased by exercise and MMA, whereas that in Lo-F was sustained at a high level (>0.8) in all settings. HF significantly decreased dynamic HR and CO regulation in all situations. In HF, the coherence for HR-CO in Lo-F decreased significantly in all settings; the coherence for SV-CO in Lo-F was significantly higher. We conclude that dynamic exercise and MMA reduces dynamic baroreflex control of HR and CO, and these are substantially impaired in HF. In N conditions, HR modulation plays a major role in CO regulation. In HF, influence of HR modulation wanes, and fluctuations of SV dominate in CO variations.

Ichinose, Masashi; Sala-Mercado, Javier A.; Coutsos, Matthew; Li, ZhenHua; Ichinose, Tomoko K.; Dawe, Elizabeth; Fano, Dominic

2012-01-01

199

Acute Heart Failure With Low Cardiac Output: Can We Develop a Short-term Inotropic Agent That Does Not Increase Adverse Events?  

Microsoft Academic Search

Acute heart failure represents an increasingly common cause of hospitalization, and may require the use of inotropic drugs\\u000a in patients with low cardiac output and evidence of organ hypoperfusion. However, currently available therapies may have deleterious\\u000a effects and increase mortality. An ideal inotropic drug should restore effective tissue perfusion by enhancing myocardial\\u000a contractility without causing adverse effects. Such a drug

Umberto Campia; Savina Nodari; Mihai Gheorghiade

2010-01-01

200

A new impedance cardiograph device for the non-invasive evaluation of cardiac output at rest and during exercise: comparison with the “direct” Fick method  

Microsoft Academic Search

The objectives of this study were to evaluate the reliability and accuracy of a new impedance cardiograph device, the Physio\\u000a Flow, at rest and during a steady-state dynamic leg exercise (work intensity ranging from 10 to 50?W) performed in the supine\\u000a position. We compared cardiac output determined simultaneously by two methods, the Physio Flow (Q?\\u000a cPF) and the direct Fick

Anne Charloux; Evelyne Lonsdorfer-Wolf; Ruddy Richard; Eliane Lampert; Monique Oswald-Mammosser; Bertrand Mettauer; Bernard Geny; Jean Lonsdorfer

2000-01-01

201

Comparison Between Cardiac Output Measured by the Pulmonary Arterial Thermodilution Technique and that Measured by the Femoral Arterial Thermodilution Technique in a Pediatric Animal Model  

Microsoft Academic Search

This study compares the correlation between two methods for the determination of cardiac output—the pulmonary arterial thermodilution technique using the Swan–Ganz catheter and the femoral arterial thermodilution technique using a pulse contour analysis computer (PiCCO) catheter. We performed a prospective animal study using 16 immature Maryland pigs weighing 9 to 16 kg. A 5.5- or 7.5-Fr Swan–Ganz catheter was introduced

M. Rupérez; J. López-Herce; C. García; C. Sánchez; E. García; D. Vigil

2004-01-01

202

Cardiac Output Measurement in Ventilated Lambs with a Significant Left-to-Right Shunt Using the Modified Carbon Dioxide Fick Method  

Microsoft Academic Search

Background: It remains a great challenge to measure systemic blood flow in critically ill newborns. In a former study we validated the modified carbon dioxide Fick (mCO2F) method for measurement of cardiac output in a newborn lamb model. In this new study we studied the influence of a left-to-right shunt on the accuracy of the mCO2F method. Objective: To analyze

Willem P. de Boode; Jeroen C. W. Hopman; Marc H. W. A. Wijnen; Ronald B. Tanke; Hans G. van der Hoeven; K. Djien Liem

2010-01-01

203

Role of heart rate and stroke volume during muscle metaboreflex-induced cardiac output increase: differences between activation during and after exercise  

Microsoft Academic Search

We hypothesized that the role of stroke volume (SV) in the metaboreflex-induced cardiac output (CO) increase was blunted when\\u000a the metaboreflex was stimulated by exercise muscle ischemia (EMI) compared with post-exercise muscle ischemia (PEMI), because\\u000a during EMI heart rate (HR) increases and limits diastolic filling. Twelve healthy volunteers were recruited and their hemodynamic\\u000a responses to the metaboreflex evoked by EMI,

Antonio Crisafulli; Francesco Piras; Michele Filippi; Carlo Piredda; Paolo Chiappori; Franco Melis; Raffaele Milia; Filippo Tocco; Alberto Concu

204

Differences of cardiac output measurements by open-circuit acetylene uptake in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: a cohort study  

PubMed Central

Background As differences in gas exchange between pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) have been demonstrated, we asked if cardiac output measurements determined by acetylene (C2H2) uptake significantly differed in these diseases when compared to the thermodilution technique. Method Single-breath open-circuit C2H2 uptake, thermodilution, and cardiopulmonary exercise testing were performed in 72 PAH and 32 CTEPH patients. Results In PAH patients the results for cardiac output obtained by the two methods showed an acceptable agreement with a mean difference of -0.16 L/min (95% CI -2.64 to 2.32 L/min). In contrast, the agreement was poorer in the CTEPH group with the difference being -0.56 L/min (95% CI -4.96 to 3.84 L/min). Functional dead space ventilation (44.5 ± 1.6 vs. 32.2 ± 1.4%, p < 0.001) and the mean arterial to end-tidal CO2 gradient (9.9 ± 0.8 vs. 4.1 ± 0.5 mmHg, p < 0.001) were significantly elevated among CTEPH patients. Conclusion Cardiac output evaluation by the C2H2 technique should be interpreted with caution in CTEPH, as ventilation to perfusion mismatching might be more relevant than in PAH.

2012-01-01

205

Cardiac output and cardiac index measured with cardiovascular magnetic resonance in healthy subjects, elite athletes and patients with congestive heart failure  

PubMed Central

Background Cardiovascular Magnetic Resonance (CMR) enables non-invasive quantification of cardiac output (CO) and thereby cardiac index (CI, CO indexed to body surface area). The aim of this study was to establish if CI decreases with age and compare the values to CI for athletes and for patients with congestive heart failure (CHF). Methods CI was measured in 144 healthy volunteers (39?±?16?years, range 21–81?years, 68 females), in 60 athletes (29?±?6?years, 30 females) and in 157 CHF patients with ejection fraction (EF) below 40% (60?±?13?years, 33 females). CI was calculated using aortic flow by velocity-encoded CMR and is presented as mean?±?SD. Flow was validated in vitro using a flow phantom and in 25 subjects with aorta and pulmonary flow measurements. Results There was a slight decrease of CI with age in healthy subjects (8?ml/min/m2 per year, r2?=?0.07, p?=?0.001). CI in males (3.2?±?0.5?l/min/m2) and females (3.1?±?0.4?l/min/m2) did not differ (p?=?0.64). The mean?±?SD of CI in healthy subjects in the age range of 20–29 was 3.3?±?0.4?l/min/m2, in 30–39?years 3.3?±?0.5?l/min/m2, in 40–49?years 3.1?±?0.5?l/min/m2, 50–59?years 3.0?±?0.4?l/min/m2 and >60?years 3.0?±?0.4?l/min/m2. There was no difference in CI between athletes and age-controlled healthy subjects but HR was lower and indexed SV higher in athletes. CI in CHF patients (2.3?±?0.6?l/min/m2) was lower compared to the healthy population (p?

2012-01-01

206

Reduced heart rate and cardiac output differentially affect angiogenesis, growth, and development in early chicken embryos (Gallus domesticus).  

PubMed

An increase in both vascular circumferential tension and shear stress in the developing vasculature of the chicken embryo has been hypothesized to stimulate angiogenesis in the developing peripheral circulation chorioallantoic membrane (CAM). To test this hypothesis, angiogenesis in the CAM, development, and growth were measured in the early chicken embryo, following acute and chronic topical application of the purely bradycardic drug ZD7288. At hour 56, ZD7288 reduced heart rate (f(H)) by ~30% but had no significant effect on stroke volume (~0.19 ± 0.2 ?L), collectively resulting in a significant fall in cardiac output (CO) from ~27 ± 3 to 18 ± 2 ?L min(-1). Mean f(H) at 72 h of development was similarly significantly lowered by acute ZD7288 treatment (250 ?M) to 128 ± 0.3 beats min(-1), compared with 174.5 ± 0.3 and 174.7 ± 0.8 beats min(-1) in control and Pannett-Compton (P-C) saline-treated embryos, respectively. Chronic dosing with ZD7288-and the attendant decreases in f(H) and CO-did not change eye diameter or cervical flexion (key indicators of development rate) at 120 h but significantly reduced overall growth (wet and dry body mass decreased by 20%). CAM vessel density index (reflecting angiogenesis) measured 200-400 ?m from the umbilical stalk was not altered, but ZD7288 reduced vessel numbers-and therefore vessel density-by 13%-16% more distally (500-600 ?m from umbilical stalk) in the CAM. In the ZD7288-treated embryos, a decrease in vessel length was found within the second branch order (~300-400 ?m from the umbilical stock), while a decrease in vessel diameter was found closer to the umbilical stock, beginning in the first branch order (~200-300 ?m). Paradoxically, chronic application of P-C saline also reduced peripheral CAM vessel density index at 500 and 600 ?m by 13% and 7%, respectively, likely from washout of local angiogenic factors. In summary, decreased f(H) with reduced CO did not slow development rate but reduced embryonic growth rate and angiogenesis in the CAM periphery. This study demonstrates for the first time that different processes in the ontogeny of the early vertebrate embryo (i.e., hypertrophic growth vs. development) have differential sensitivities to altered convective blood flow. PMID:23629887

Branum, Sylvia R; Yamada-Fisher, Miho; Burggren, Warren

2013-04-19

207

Human cardiac stem cells exhibit mesenchymal features and are maintained through Akt/GSK-3{beta} signaling  

SciTech Connect

Recent evidence suggested that human cardiac stem cells (hCSCs) may have the clinical application for cardiac repair; however, their characteristics and the regulatory mechanisms of their growth have not been fully investigated. Here, we show the novel property of hCSCs with respect to their origin and tissue distribution in human heart, and demonstrate the signaling pathway that regulates their growth and survival. Telomerase-active hCSCs were predominantly present in the right atrium and outflow tract of the heart (infant > adult) and had a mesenchymal cell-like phenotype. These hCSCs expressed the embryonic stem cell markers and differentiated into cardiomyocytes to support cardiac function when transplanted them into ischemic myocardium. Inhibition of Akt pathway impaired the hCSC proliferation and induced apoptosis, whereas inhibition of glycogen synthase kinase-3 (GSK-3) enhanced their growth and survival. We conclude that hCSCs exhibit mesenchymal features and that Akt/GSK-3{beta} may be crucial modulators for hCSC maintenance in human heart.

Tateishi, Kento [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan)]|[Department of Cardiovascular Medicine, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan); Ashihara, Eishi [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan); Honsho, Shoken [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan)]|[Department of Cardiovascular Medicine, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan); Takehara, Naofumi [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan); Nomura, Tetsuyaital [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan)]|[Department of Cardiovascular Medicine, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan); Takahashi, Tomosaburo [Department of Cardiovascular Medicine, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan); Ueyama, Tomomi [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan); Yamagishi, Masaaki; Yaku, Hitoshi [Department of Cardiovascular Surgery, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan); Matsubara, Hiroaki [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan)]|[Department of Cardiovascular Medicine, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan)]. E-mail: matsubah@koto.kpu-m.ac.jp; Oh, Hidemasa [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan)]. E-mail: hidemasa@kuhp.kyoto-u.ac.jp

2007-01-19

208

Cardiac output measured by uncalibrated arterial pressure waveform analysis by recently released software version 3.02 versus thermodilution in septic shock.  

PubMed

To evaluate the 3.02 software version of the FloTrac/Vigileo™ system for estimation of cardiac output by uncalibrated arterial pressure waveform analysis, in septic shock. Nineteen consecutive patients in septic shock were studied. FloTrac/Vigileo™ measurements (COfv) were compared with pulmonary artery catheter thermodilution-derived cardiac output (COtd). The mean cardiac output was 7.7 L min(-1) and measurements correlated at r = 0.53 (P < 0.001, n = 314). In Bland-Altman plot for repeated measurements, the bias was 1.7 L min(-1) and 95 % limits of agreement (LA) were -3.0 to 6.5 L min(-1), with a %error of 53 %. The bias of COfv inversely related to systemic vascular resistance (SVR) (r = -0.54, P < 0.001). Above a SVR of 700 dyn s cm(-5) (n = 74), bias was 0.3 L min(-1) and 95 % LA were -1.6 to 2.2 L min(-1) (%error 32 %). Changes between consecutive measurements (n = 295) correlated at 0.67 (P < 0.001), with a bias of 0.1 % (95 % limits of agreement -17.5 to 17.0 %). All changes >10 % in both COtd and COfv (n = 46) were in the same direction. Eighty-five percent of the measurements were within the 30°-330° of the polar axis. COfv with the latest software still underestimates COtd at low SVR in septic shock. The tracking capacities of the 3.02 software are moderate-good when clinically relevant changes are considered. PMID:23154918

Slagt, Cornelis; de Leeuw, Marcel A; Beute, Jan; Rijnsburger, Emmy; Hoeksema, Martijn; Mulder, Jan W R; Malagon, Ignacio; Groeneveld, A B Johan

2012-11-15

209

Co-administration of ephedrine prevents reductions in cardiac output and systemic oxygen delivery secondary to lung compression maneuvers during one-lung ventilation, without reducing arterial oxygenation  

Microsoft Academic Search

Purpose  We previously showed that compression of the nondependent lung during one-lung ventilation (OLV) in patients undergoing esophagectomy\\u000a improves arterial oxygenation but impairs cardiac output (CO) and systemic oxygen delivery (DO2). The objective of this study was to test the hypothesis that the combination of nondependent lung compression and ephedrine\\u000a improves arterial oxygenation without compromising DO2.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Twenty patients undergoing esophagectomy through

Seiji Ishikawa; Fumi Makino; Satomi Kobinata; Hiroyuki Ito; Tatsuyuki Kawano; Koshi Makita

2011-01-01

210

Compressing the non-dependent lung during one-lung ventilation improves arterial oxygenation, but impairs systemic oxygen delivery by decreasing cardiac output  

Microsoft Academic Search

Purpose  We have previously found that compression of the non-dependent lung improves arterial oxygenation during one-lung ventilation\\u000a (OLV) in patients undergoing esophagectomy. The purpose of this study was to investigate the effects of compression of the\\u000a non-dependent lung on hemodynamic indices and oxygen delivery using a minimally invasive cardiac output (CO) monitor.\\u000a \\u000a \\u000a \\u000a Methods  Sixteen consecutive patients undergoing esophagectomy through a right thoracotomy

Seiji Ishikawa; Madoka Shirasawa; Michiko Fujisawa; Tatsuyuki Kawano; Koshi Makita

2010-01-01

211

Short term correction of anaemia with recombinant human erythropoietin and reduction of cardiac output in end stage renal failure.  

PubMed Central

Children with end stage renal failure and anaemia have an increased cardiac index and often gross ventricular hypertrophy. The contribution of anaemia to these abnormalities is uncertain. Eleven children with end stage renal failure and anaemia (haemoglobin concentration < 90 g/l) were enrolled into a single blind, placebo controlled, crossover study to assess the cardiovascular effects of reversing anaemia using subcutaneous human recombinant erythropoietin (r-HuEpo). Each limb lasted 24 weeks; seven children completed both limbs of the study. Haemoglobin increased with r-HuEpo, remaining above 100 g/l for a mean of 11 weeks. Cardiac index fell as a result of a reduction in both left ventricular stroke volume and heart rate. Left ventricular end diastolic diameter also decreased. In five children left ventricular wall thickness and left ventricular mass decreased with r-HuEpo, but this failed to reach significance for the whole group. Blood pressure did not change in six normotensive children completing an r-HuEpo limb; the decrease in cardiac index was therefore balanced by an increase in peripheral vascular resistance. Three children were taking anti-hypertensive treatment at the start of the study; one required an increase, and one a decrease, in treatment during the r-HuEpo limb. Short term treatment with r-HuEpo reduces cardiac index. A longer study is needed to determine whether this will, in time, result in a significant reduction in left ventricular hypertrophy.

Morris, K P; Skinner, J R; Hunter, S; Coulthard, M G

1993-01-01

212

The Transcriptional Coactivators, PGC-1? and ?, Cooperate to Maintain Cardiac Mitochondrial Function During the Early Stages of Insulin Resistance  

PubMed Central

We previously demonstrated a cardiac mitochondrial biogenic response in insulin resistant mice that requires the nuclear receptor transcription factor PPAR?. We hypothesized that the PPAR? coactivator peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1?) is necessary for mitochondrial biogenesis in insulin resistant hearts and that this response was adaptive. Mitochondrial phenotype was assessed in insulin resistant mouse models in wild-type (WT) versus PGC-1? deficient (PGC-1??/?) backgrounds. Both high fat-fed (HFD) WT and 6 week-old Ob/Ob animals exhibited a significant increase in myocardial mitochondrial volume density compared to standard chow fed or WT controls. In contrast, HFD PGC-1??/? and Ob/Ob-PGC-1??/? hearts lacked a mitochondrial biogenic response. PGC-1? gene expression was increased in 6 week-old Ob/Ob animals, followed by a decline in 8 week-old Ob/Ob animals with more severe glucose intolerance. Mitochondrial respiratory function was increased in 6 week-old Ob/Ob animals, but not in Ob/Ob-PGC-1??/? mice and not in 8 week-old Ob/Ob animals, suggesting a loss of the early adaptive response, consistent with the loss of PGC-1? upregulation. Animals that were deficient for PGC-1? and heterozygous for the related coactivator PGC-1? (PGC-1??/??+/?) were bred to the Ob/Ob mice. Ob/Ob-PGC-1??/??+/? hearts exhibited dramatically reduced mitochondrial respiratory capacity. Finally, the mitochondrial biogenic response was triggered in H9C2 myotubes by exposure to oleate, an effect that was blunted with shRNA-mediated PGC-1 “knockdown”. We conclude that PGC-1 signaling is important for the adaptive cardiac mitochondrial biogenic response that occurs during the early stages of insulin resistance. This response occurs in a cell autonomous manner and likely involves exposure to high levels of free fatty acids.

Mitra, Riddhi; Nogee, Daniel P.; Zechner, Juliet F.; Yea, Kyungmoo; Gierasch, Carrie M.; Kovacs, Attila; Medeiros, Denis M.; Kelly, Daniel P.; Duncan, Jennifer G.

2012-01-01

213

Construct, concurrent and discriminant validity of Type D personality in the general population: associations with anxiety, depression, stress and cardiac output.  

PubMed

The Type D personality, identified by high negative affectivity paired with high social inhibition, has been associated with a number of health-related outcomes in (mainly) cardiac populations. However, despite its prevalence in the health-related literature, how this personality construct fits within existing personality theory has not been directly tested. Using a sample of 134 healthy university students, this study examined the Type D personality in terms of two well-established personality traits; introversion and neuroticism. Construct, concurrent and discriminant validity of this personality type was established through examination of the associations between the Type D personality and psychometrically assessed anxiety, depression and stress, as well as measurement of resting cardiovascular function. Results showed that while the Type D personality was easily represented using alternative measures of both introversion and neuroticism, associations with anxiety, depression and stress were mainly accounted for by neuroticism. Conversely, however, associations with resting cardiac output were attributable to the negative affectivity-social inhibition synergy, explicit within the Type D construct. Consequently, both the construct and concurrent validity of this personality type were confirmed, with discriminant validity evident on examination of physiological indices of well-being. PMID:21809947

Howard, Siobhán; Hughes, Brian M

2011-08-02

214

[Summary of the consensus document: "Clinical practice guide for the management of low cardiac output syndrome in the postoperative period of heart surgery"].  

PubMed

Low cardiac output syndrome is a potential complication in cardiac surgery patients and is associated with increased morbidity and mortality. This guide provides recommendations for the management of these patients, immediately after surgery and following admission to the ICU. The recommendations are grouped into different sections, addressing from the most basic concepts such as definition of the disorder to the different sections of basic and advanced monitoring, and culminating with the complex management of this syndrome. We propose an algorithm for initial management, as well as two others for ventricular failure (predominantly left or right). Most of the recommendations are based on expert consensus, due to the lack of randomized trials of adequate design and sample size in patients of this kind. The quality of evidence and strength of the recommendations were based on the GRADE methodology. The guide is presented as a list of recommendations (with the level of evidence for each recommendation) for each question on the selected topic. For each question, justification of the recommendations is then provided. PMID:22445904

Pérez Vela, J L; Martín Benitez, J C; Carrasco Gonzalez, M; de la Cal López, M A; Hinojosa Pérez, R; Sagredo Meneses, V; del Nogal Saez, F

2012-03-23

215

Rehabilitating elderly cardiac patients.  

PubMed Central

The aging cardiovascular system undergoes many anatomic and physiologic changes. Increased vascular resistance, myocardial "stiffness," abnormalities of rhythmicity of the sinoatrial node, irregular cardiac rhythms, and alterations in heart rate and blood pressure responses are all seen more frequently in older patients. These changes are likely to impair these patients' ability to make the rapid adjustments necessary to maintain cardiac output during exercise and activity. When cardiovascular disease processes are superimposed on the "normal" concomitants of aging, greater alterations in hemodynamic response to exercise activity are noted than usually occur in younger cardiac patients. Exercise testing of older cardiac patients is safe and is usually needed to prescribe an appropriate intensity of exercise activity. The choice of the exercise protocol, the timing of the exercise test in relation to taking prescribed cardiac medication, the choice of exercise equipment, and special considerations for devices such as pacemakers and automatic implantable cardiodefibrillators must be considered before the exercise test is done. Many of these factors and the presence of either silent or overt cardiac symptoms or untoward hemodynamic events will also affect the exercise prescription. Elderly patients usually show substantial functional improvement when participating in a cardiac rehabilitation program and comply well with prescribed exercise. Early educational intervention may be crucial to reducing disability in these patients.

Anderson, J. M.

1991-01-01

216

Estimation of cardiac output and systemic vascular resistance using a multivariate regression model with features selected from the finger photoplethysmogram and routine cardiovascular measurements  

PubMed Central

Background Cardiac output (CO) and systemic vascular resistance (SVR) are two important parameters of the cardiovascular system. The ability to measure these parameters continuously and noninvasively may assist in diagnosing and monitoring patients with suspected cardiovascular diseases, or other critical illnesses. In this study, a method is proposed to estimate both the CO and SVR of a heterogeneous cohort of intensive care unit patients (N=48). Methods Spectral and morphological features were extracted from the finger photoplethysmogram, and added to heart rate and mean arterial pressure as input features to a multivariate regression model to estimate CO and SVR. A stepwise feature search algorithm was employed to select statistically significant features. Leave-one-out cross validation was used to assess the generalized model performance. The degree of agreement between the estimation method and the gold standard was assessed using Bland-Altman analysis. Results The Bland-Altman bias ±precision (1.96 times standard deviation) for CO was -0.01 ±2.70 L min-1 when only photoplethysmogram (PPG) features were used, and for SVR was -0.87 ±412 dyn.s.cm-5 when only one PPG variability feature was used. Conclusions These promising results indicate the feasibility of using the method described as a non-invasive preliminary diagnostic tool in supervised or unsupervised clinical settings.

2013-01-01

217

Use of a capillary input function with cardiac output for the estimation of lesion pharmacokinetic parameters: preliminary results on a breast cancer patient  

NASA Astrophysics Data System (ADS)

The objective of this work was to propose and demonstrate a novel technique for the assessment of tumour pharmacokinetic parameters together with a regionally estimated vascular input function. A breast cancer patient T2*-weighted dynamic contrast enhanced MRI (DCE-MRI) dataset acquired at high temporal resolution during the first-pass bolus perfusion was used for testing the technique. Extraction of the lesion volume transfer constant Ktrans together with the intravascular plasma volume fraction vp was achieved by optimizing a capillary input function with a measure of cardiac output using the principle of intravascular indicator dilution theory. For a region of interest drawn within the breast lesion a vp of 0.16 and a Ktrans of 0.70 min-1 were estimated. Despite the value of vp being higher than expected, estimated Ktrans was in accordance with the literature values. In conclusion, the technique proposed here, has the main advantage of allowing the estimation of breast tumour pharmacokinetic parameters from first-pass perfusion T2*-weighted DCE-MRI data without the need of measuring an arterial input function. The technique may also have applicability to T1-weighted DCE-MRI data.

Di Giovanni, P.; Ahearn, T. S.; Semple, S. I.; Azlan, C. A.; Lloyd, W. K. C.; Gilbert, F. J.; Redpath, T. W.

2011-03-01

218

Cross-comparison of cardiac output trending accuracy of LiDCO, PiCCO, FloTrac and pulmonary artery catheters  

PubMed Central

Introduction Although less invasive than pulmonary artery catheters (PACs), arterial pulse pressure analysis techniques for estimating cardiac output (CO) have not been simultaneously compared to PAC bolus thermodilution CO (COtd) or continuous CO (CCO) devices. Methods We compared the accuracy, bias and trending ability of LiDCO™, PiCCO™ and FloTrac™ with PACs (COtd, CCO) to simultaneously track CO in a prospective observational study in 17 postoperative cardiac surgery patients for the first 4 hours following intensive care unit admission. Fifty-five paired simultaneous quadruple CO measurements were made before and after therapeutic interventions (volume, vasopressor/dilator, and inotrope). Results Mean CO values for PAC, LiDCO, PiCCO and FloTrac were similar (5.6 ± 1.5, 5.4 ± 1.6, 5.4 ± 1.5 and 6.1 ± 1.9 L/min, respectively). The mean CO bias by each paired method was -0.18 (PAC-LiDCO), 0.24 (PAC-PiCCO), -0.43 (PAC-FloTrac), 0.06 (LiDCO-PiCCO), -0.63 (LiDCO-FloTrac) and -0.67 L/min (PiCCO-FloTrac), with limits of agreement (1.96 standard deviation, 95% confidence interval) of ± 1.56, ± 2.22, ± 3.37, ± 2.03, ± 2.97 and ± 3.44 L/min, respectively. The instantaneous directional changes between any paired CO measurements displayed 74% (PAC-LiDCO), 72% (PAC-PiCCO), 59% (PAC-FloTrac), 70% (LiDCO-PiCCO), 71% (LiDCO-FloTrac) and 63% (PiCCO-FloTrac) concordance, but poor correlation (r2 = 0.36, 0.11, 0.08, 0.20, 0.23 and 0.11, respectively). For mean CO < 5 L/min measured by each paired devices, the bias decreased slightly. Conclusions Although PAC (COTD/CCO), FloTrac, LiDCO and PiCCO display similar mean CO values, they often trend differently in response to therapy and show different interdevice agreement. In the clinically relevant low CO range (< 5 L/min), agreement improved slightly. Thus, utility and validation studies using only one CO device may potentially not be extrapolated to equivalency of using another similar device.

2010-01-01

219

Heat shock protein 27 is increased in cyanotic tetralogy of Fallot myocardium and is associated with improved cardiac output and contraction.  

PubMed

Tetralogy of Fallot (TOF) is a congenital heart condition in which the right ventricle is exposed to cyanosis and pressure overload. Patients have an increased risk of right ventricle dysfunction following corrective surgery. Whether the cyanotic myocardium is less tolerant of injury compared to non-cyanotic is unclear. Heat shock proteins (HSPs) protect against cellular stresses. The aim of this study was to examine HSP 27 expression in the right ventricle resected from TOF patients and determine its relationship with right ventricle function and clinical outcome. Ten cyanotic and ten non-cyanotic patients were studied. Western blotting was used to quantify HSP 27 in resected myocardium at (1) baseline (first 15 min of aortic cross clamp and closest representation of pre-operative status) and (2) after 15 min during ischemia until surgery was complete. The cyanotic group had significantly increased haematocrit, lower O2 saturation, thicker interventricular septal wall thickness and released more troponin-I on post-operative day 1 (p < 0.05). HSP 27 expression was significantly increased in the < 15 min cyanotic compared to the < 15 min non-cyanotic group (p = 0.03). In the cyanotic group, baseline HSP 27 expression also significantly correlated with oxygen extraction ratio (p = 0.028), post-operative basal septal velocity (p = 0.036) and mixed venous oxygen saturation (p = 0.02), markers of improved cardiac output/contraction. Increased HSP 27 expression and associated improved right ventricle function and systemic perfusion supports a cardio-protective effect of HSP 27 in cyanotic TOF. PMID:23080524

Walker, Susan; Danton, Mark; Peng, Edward Weng Koon; Lyall, Fiona

2012-10-19

220

Varying the heart rate response to dynamic exercise in pacemaker-dependent subjects: effects on cardiac output and cerebral blood velocity.  

PubMed

Cerebral blood flow increases upon the transition from rest to moderate exercise, but becomes affected when the ability to raise CO (cardiac output) is limited. HR (heart rate) is considered to contribute significantly to the increase in CO in the early stages of dynamic exercise. The aim of the present study was to test whether manipulation of the HR response in patients dependent on permanent rate-responsive ventricular pacing contributes to the increase in CO, MCA V(mean) [mean MCA (middle cerebral artery) velocity] and work capacity during exercise. The effect of setting the pacemaker to DSS ('default' sensor setting) compared with OSS ('optimized' sensor setting) on blood pressure, CO, SV (stroke volume) and MCA V(mean) was evaluated during ergometry cycling. From rest to exercise at 75 W, the rise in HR in OSS [from 73 (65-87) to 116 (73-152) beats/min; P<0.05] compared with DSS [70 (60-76) to 97 (67-117) beats/min; P<0.05] was larger. There was an increase in SV during exercise with DSS, but not with OSS, such that, at all workloads, SVs were greater during DSS than OSS. The slope of the HR-CO relationship was larger with DSS than OSS (P<0.05). From rest to exercise, MCA V(sys) (systolic MCA velocity) increased in OSS and DSS, and MCA V(dias) (diastolic MCA velocity) was reduced with DSS. No changes were observed in MCA V(mean). Manipulation of the pacemaker setting had no effect on the maximal workload [133 (100-225) W in OSS compared with 129 (75-200) W in DSS]. The results indicate that, in pacemaker-dependent subjects with complete heart block and preserved myocardial function, enhancing the HR response to exercise neither augments CO by a proportional offset of the exercise-induced increase in SV nor improves cerebral perfusion. PMID:16038616

Bogert, Lysander W J; Erol-Yilmaz, Ayten; Tukkie, Raymond; Van Lieshout, Johannes J

2005-12-01

221

Effects of reduced rebreathing time, in spontaneously breathing patients, on respiratory effort and accuracy in cardiac output measurement when using a partial carbon dioxide rebreathing technique: a prospective observational study  

Microsoft Academic Search

Introduction  New technology using partial carbon dioxide rebreathing has been developed to measure cardiac output. Because rebreathing\\u000a increases respiratory effort, we investigated whether a newly developed system with 35 s rebreathing causes a lesser increase\\u000a in respiratory effort under partial ventilatory support than does the conventional system with 50 s rebreathing. We also investigated\\u000a whether the shorter rebreathing period affects the

Kazuya Tachibana; Hideaki Imanaka; Muneyuki Takeuchi; Tomoyo Nishida; Yuji Takauchi; Masaji Nishimura

2005-01-01

222

Control strategy for maintaining physiological perfusion with rotary blood pumps.  

PubMed

We present arguments and simulation results in favor of a novel strategy for control of rotary blood pumps. We suggest that physiological perfusion is achieved when the blood pump is controlled to maintain an average reference differential pressure. In the case of rotary left ventricular assist devices, our simulations show that maintaining a constant average pressure difference between the left ventricle and aorta results in physiological perfusion over a wide range of physical activities and clinical cardiac conditions. We simulated rest, light, and strenuous exercise conditions, corresponding to cardiac demands of 4.92, 7.98, and 14.62 L/min, respectively. For different exercise levels, the clinical conditions ranged from normal to failing to asystolic heart. By maintaining a constant pressure difference of 75 mm Hg between the left ventricle and aorta, with either an axial or a centrifugal blood pump, a total cardiac output close to the physiological cardiac demand was achieved, irrespective of the heart condition. The simulations of the transitions between different levels of exercise indicate that with the same reference differential pressure, the proposed approach leads to rapid adaptation of the total cardiac output to physiological levels, while avoiding suction. Comparison with the traditional control strategy of maintaining a reference rotational speed (rpm) of the pump indicates that though the traditional approach has some degree of adaptability, it is only adequate over a narrow range of cardiac demand and clinical conditions of the patient. Our results indicate that the proposed approach is superior to the alternatives in providing an adequate and autonomous adaptation of the total cardiac output over a broad range of exercise conditions (expected when an assist device is used as a destination therapy) and clinical statuses of the native heart (such as further deterioration or recovery of cardiac function), while having the potential to improve the quality of life of patients by reducing the need for monitoring and frequent human intervention. The proposed approach can be clinically implemented using simple controllers, and requires the implantation of two pressure sensors, or estimation of the pressure difference based on other available measurements. PMID:12823419

Giridharan, Guruprasad A; Skliar, Mikhail

2003-07-01

223

Effects of levosimendan/furosemide infusion on Plasma Brain Natriuretic Peptide, echocardiographic parameters and cardiac output in end-stage heart failure patients  

PubMed Central

Summary Background Acute decompensation heart failure (ADHF) remains a cause of hospitalization in patients with end-stage congestive HF. The administration of levosimendan in comparison with a standard therapy in CHF patients admitted for ADHF was analysed. Material/Methods Consecutive patients admitted for ADHF (NYHA class III–IV) were treated with levosimendan infusion 0.1 ?g/kg/min or with furosemide infusion 100–160 mg per day for 48 hours (control group). All subjects underwent determination of brain natriuretic peptide (BNP), non-invasive cardiac output (CO), and echocardiogram at baseline, at the end of therapy and 1 week after therapy. Results Seven patients admitted for 20 treatments in 16 months (age 66 years; mean admission/year 5.4) were treated with levosimendan and compared with 7 patients admitted for 15 treatments (age 69.1 years; mean admission/year 6.1). At the end of levosimendan therapy, BNP decreased (from 679.7±512.1 pg/ml to 554.2±407.6 pg/ml p=0.03), and 6MWT and LVEF improved (from 217.6±97.7 m to 372.2±90.4 m p=0.0001; from 22.8±9.1% to 25.4±9.8% p=0.05). Deceleration time, E/A, E/E’, TAPSE, pulmonary pressure and CO did not change significantly after levosimendan therapy and after 1 week. At follow-up, only 6-min WT and NYHA class showed a significant improvement (p=0.0001, p=0.001 respectively). The furosemide infusion reduced NYHA class and body weight (from 3.4±0.6 to 2.3±0.5 p=0.001; from 77.5±8.6 kg to 76±6.6 kg p=0.04), but impaired renal function (clearances from 56.3±21.9 ml/min to 41.2±10.1 ml/min p=0.04). Conclusions Treating end-stage CHF patients with levosimendan improved BNP and LVEF, but this effect disappeared after 1 week. The amelioration of 6MWT and NYHA class lasted longer after levosimendan infusion.

Feola, Mauro; Lombardo, Enrico; Taglieri, Camillo; Vallauri, Paola; Piccolo, Salvatore; Valle, Roberto

2011-01-01

224

Cardiac output in idiopathic normal pressure hydrocephalus: association with arterial blood pressure and intracranial pressure wave amplitudes and outcome of shunt surgery  

PubMed Central

Background In patients with idiopathic normal pressure hydrocephalus (iNPH) responding to shunt surgery, we have consistently found elevated intracranial pressure (ICP) wave amplitudes during diagnostic ICP monitoring prior to surgery. It remains unknown why ICP wave amplitudes are increased in these patients. Since iNPH is accompanied by a high incidence of vascular co-morbidity, a possible explanation is that there is reduced vascular compliance accompanied by elevated arterial blood pressure (ABP) wave amplitudes and even altered cardiac output (CO). To investigate this possibility, the present study was undertaken to continuously monitor CO to determine if it is correlated to ABP and ICP wave amplitudes and the outcome of shunting in iNPH patients. It was specifically addressed whether the increased ICP wave amplitudes seen in iNPH shunt responders were accompanied by elevated CO and/or ABP wave amplitude levels. Methods Prospective iNPH patients (29) were clinically graded using an NPH grading scale. Continuous overnight minimally-invasive monitoring of CO and ABP was done simultaneously with ICP monitoring; the CO, ABP, and ICP parameters were parsed into 6-second time windows. Patients were assessed for shunt surgery on clinical grade, Evan's index, and ICP wave amplitude. Follow-up clinical grading was performed 12 months after surgery. Results ICP wave amplitudes but not CO or ABP wave amplitude, showed good correlation with the response to shunt treatment. The patients with high ICP wave amplitude did not have accompanying high levels of CO or ABP wave amplitude. Correlation analysis between CO and ICP wave amplitudes in individual patients showed different profiles [significantly positive in 10 (35%) and significantly negative in 16 (55%) of 29 recordings]. This depended on whether there was also a correlation between ABP and ICP wave amplitudes and on the average level of ICP wave amplitude. Conclusions These results gave no evidence that the increased levels of ICP wave amplitudes seen in iNPH shunt responders prior to surgery were accompanied by elevated levels of ABP wave amplitudes or elevated CO. In the individual patients the correlation between CO and ICP wave amplitude was partly related to an association between ABP and ICP wave amplitudes which can be indicative of the state of cerebrovascular pressure regulation, and partly related to the ICP wave amplitude which can be indicative of the intracranial compliance.

2011-01-01

225

Exercise-induced ST-segment changes permit prediction of improvement in left ventricular ischemic dysfunction after revascularization: Evaluation with positron emission tomographic measurements of regional myocardial blood flow and cardiac output  

Microsoft Academic Search

Background  Prediction of the recovery of left ventricular (LV) ischemic dysfunction after revascularization is important in patients\\u000a with coronary artery disease (CAD). We investigated whether the improvement in LV ischemic dysfunction after revascularization\\u000a could be predicted preoperatively by exercise-induced ST-segment changes.\\u000a \\u000a \\u000a \\u000a Methods and Results  Regional myocardial blood flow (RMBF) and cardiac output were measured with nitrogen 13-ammonia positron emission tomography\\u000a at rest

Takuya Watanabe; Kenichi Harumi; Tetsuo Michihatas; Osamu Okazaki; Hideyuki Yamanaka; Yasushi Akutsu; Takashi Katagiri

1998-01-01

226

High-output heart failure: how to define it, when to treat it, and how to treat it.  

PubMed

Although hemodialysis patients who initiate and maintain a permanent form of dialysis vascular access have improved all-cause and cardiovascular survival compared with those who use catheters, the presence of an arteriovenous fistula has been shown to have a short-term, adverse effect on cardiac function. Through its effect as a left-to-right extracardiac shunt, the arteriovenous fistula can increase cardiac workload substantially, and, in certain patients, result in a high-output state and resultant heart failure over time. Here we review the mechanisms by which dialysis arteriovenous access may promote the development of high-output cardiac failure in end-stage renal disease patients, describe risk factors for and the diagnosis of high-output heart failure, and suggest management strategies for patients who develop high-output heart failure. PMID:23217335

Wasse, Haimanot; Singapuri, M Salman

2012-11-01

227

The estimation of cardiac output by the Nexfin device is of poor reliability for tracking the effects of a fluid challenge  

PubMed Central

Introduction The Nexfin device estimates arterial pressure by the volume clamp method through a finger pneumatic cuff. It also allows to estimate cardiac index (CInoninv) by pulse contour analysis of the non-invasive arterial pressure curve. We evaluated the ability of the device to track changes in cardiac index induced by a fluid challenge. Methods We included 45 patients for whom a volume expansion (500 mL of saline infused over 30 min) was planned. The volume expansion-induced changes in cardiac index measured by transpulmonary thermodilution (CIinv, PiCCO device) and in CInoninv were recorded. Results In seven patients, the Nexfin could not record the arterial curve due to finger hypoperfusion. Considering both the values obtained before and after volume expansion (n = 76 pairs of measurements), the bias (lower and upper limits of agreement) between CIinv and CInoninv was 0.2 (-1.8 to 2.2) L/min/m2. The mean change in CInoninv was 10 ± 11%. The percentage error of CInoninv was 57%. The correlation between the changes in CIinv and CInoninv observed during volume expansion was significant (P = 0.0002) with an r2 = 0.31. Conclusions The estimation of CI by the Nexfin device in critically ill patients is not reliable, neither for estimating absolute values of CI nor for tracking its changes during volume expansion.

2012-01-01

228

The myocardium and the hemodynamics during cardiac hyperfunction and insufficiency. Report 2. Lowering of the resistance of the vascular field as an economic compensatory factor in diseases of the circulatory system  

Microsoft Academic Search

During gradual reproduction of experimental aortic stenosis in dogs there occurs a considerable reduction of the general vascular resistance. This shift is clearly observed not only in stenosis of the aorta, it is an important compensatory factor maintaining the normal cardiac output in economic use of the myocardial reserves. A drop in vascular resistance during intensive cardiac hyperfunction may be

F. Z. Meerson; A. L. Mikoélyan; G. I. Markovskaya; Yu. A. Vlasov

1964-01-01

229

Cardiac disease in mucopolysaccharidosis type I attributed to catecholaminergic and hemodynamic deficiencies  

PubMed Central

Cardiac dysfunction is a common cause of death among pediatric patients with mutations in the lysosomal hydrolase ?-l-iduronidase (IDUA) gene, which causes mucopolysaccharidosis type I (MPS-I). The purpose of this study was to analyze adrenergic regulation of cardiac hemodynamic function in MPS-I. An analysis of murine heart function was performed using conductance micromanometry to assess in vivo cardiac hemodynamics. Although MPS-I (IDUA?/?) mice were able to maintain normal cardiac output and ejection fraction at baseline, this cohort had significantly compromised systolic and diastolic function compared with IDUA+/? control mice. During dobutamine infusion MPS-I mice did not significantly increase cardiac output from baseline, indicative of blunted cardiac reserve. Autonomic tone, measured functionally by ?-blockade, indicated that MPS-I mice required catecholaminergic stimulation to maintain baseline hemodynamics. Survival analysis showed mortality only among MPS-I mice. Linear regression analysis revealed that heightened end-systolic volume in the resting heart is significantly correlated with susceptibility to mortality in MPS-I hearts. This study reveals that cardiac remodeling in the pathology of MPS-I involves heightened adrenergic tone at the expense of cardiac reserve with cardiac decompensation predicted on the basis of increased baseline systolic volumes.

Palpant, Nathan J.; Bedada, Fikru B.; Peacock, Brandon; Blazar, Bruce R.; Metzger, Joseph M.

2011-01-01

230

Cardiac Output Responses During Exercise in Volume-Expanded Heart Transplant Recipients 1 1 This work was supported by National Institutes of Health Clinical Research Center Grant RR00082 and Dr. Braith was supported by a NIH National Research Service Award (HL08777), Bethesda, Maryland  

Microsoft Academic Search

The mechanisms responsible for immediate adjustments in cardiac output at onset of exercise, in the absence of neural drive, are not well defined in heart transplant (HT) recipients. Seven male HT recipients (mean ± SD 57 ± 6 years) and 7 age-matched sedentary normal control subjects (mean age 57 ± 5 years) performed constant load cycle exercise at 40% of

Randy W Braith; Mary B Plunkett; Roger M Mills

1998-01-01

231

Antarctic fish can compensate for rising temperatures: thermal acclimation of cardiac performance in Pagothenia borchgrevinki.  

PubMed

Antarctic fish Pagothenia borchgrevinki in McMurdo Sound, Antarctica, inhabit one of the coldest and most thermally stable of all environments. Sea temperatures under the sea ice in this region remain a fairly constant -1.86 degrees C year round. This study examined the thermal plasticity of cardiac function in P. borchgrevinki to determine whether specialisation to stable low temperatures has led to the loss of the ability to acclimate physiological function. Fish were acclimated to -1 degree C and 4 degrees C for 4-5 weeks and cardiac output was measured at rest and after exhaustive exercise in fish acutely transferred from their acclimation temperature to -1, 2, 4, 6 and 8 degrees C. In the -1 degree C acclimated fish, the factorial scope for cardiac output was greatest at -1 degree C and decreased with increasing temperature. Increases in cardiac output with exercise in the -1 degree C acclimated fish was achieved by increases in both heart rate and stroke volume. With acclimation to 4 degrees C, resting cardiac output was thermally independent across the test temperatures; furthermore, factorial scope for cardiac output was maintained at 4, 6 and 8 degrees C, demonstrating thermal compensation of cardiac function at the higher temperatures. This was at the expense of cardiac function at -1 degrees C, where there was a significant decrease in factorial scope for cardiac output in the 4 degrees C acclimated fish. Increases in cardiac output with exercise in the 4 degrees C acclimated fish at the higher temperatures was achieved by changes in heart rate alone, with stroke volume not varying between rest and exercise. The thermal compensation of cardiac function in P. borchgrevinki at higher temperatures was the result of a change in pumping strategy from a mixed inotropic/chronotropic modulated heart in -1 degrees C acclimated fish at low temperatures to a purely chronotropic modulated heart in the 4 degrees C acclimated fish at higher temperatures. In spite of living in a highly stenothermal cold environment, P. borchgrevinki demonstrated the capacity to thermally acclimate cardiac function to elevated temperatures, thereby allowing the maintenance of factorial scope and the support of aerobic swimming at higher temperatures. PMID:17704081

Franklin, Craig E; Davison, William; Seebacher, Frank

2007-09-01

232

Applications of minimally invasive cardiac output monitors  

PubMed Central

Because of the increasing age of the population, critical care and emergency medicine physicians have seen an increased number of critically ill patients over the last decade. Moreover, the trend of hospital closures in the United States t imposes a burden of increased efficiency. Hence, the identification of devices that facilitate accurate but rapid assessments of hemodynamic parameters without the added burden of invasiveness becomes tantamount. The purpose of this review is to understand the applications and limitations of these new technologies.

2012-01-01

233

Development of a Pacemaker Monitor with Cardiac Simulator.  

National Technical Information Service (NTIS)

A cardiac pacemaker monitoring system was developed for use in testing cardiac pacemakers in RF fields. The system provided for both continuous monitoring of the pacemaker output and simulating normal cardiac activity at the pacemaker leads. Fiber optics ...

T. O. Steiner

1975-01-01

234

Experimental study of afterload-reducing therapy: the effects of the reduction of systemic vascular resistance on cardiac output, aortic pressure and coronary circulation in isolated, ejecting canine hearts.  

PubMed

The relationship between cardiac output (CO) and peripheral resistance (Rp) was examined under the following conditions for coronary perfusion: constant coronary flow perfusion; perfusion with a pressure equal to mean aortic pressure (AoP perfusion); and perfusion with a pressure equal to the mean AoP - 30 mm Hg (AoP - 30 mm Hg perfusion). We also examined the coronary pressure-flow relationship. For these studies, we used paced, isolated, ejecting canine hearts, which were loaded by a hydraulic system that simulated the input impedance of a dog's systemic arterial tree. The CO in the constant coronary flow perfusion continued to increase with the reduction of Rp. The CO in the AoP perfusion became maximal at a slightly subphysiologic Rp, or at an average mean AoP of 65 mm Hg. This mean AoP was closely associated with the lower limit of the autoregulation of coronary blood flow. In the AoP - 30 mm Hg perfusion, the mean AoP at which CO became maximal was 72 mm Hg and the corresponding coronary perfusion pressure appeared to be lower than the lower limit of the perfusion pressure range for coronary flow autoregulation. The Rp value at that point was slightly higher than the physiologic range. We conclude that when coronary perfusion pressure changes with mean AoP, and when left ventricular end-diastolic pressure is fixed, there is a clear optimal Rp at which CO becomes maximal, and this optimal Rp is higher if coronary perfusion pressure is biased from mean AoP to a significant degree. PMID:7261281

Isoyama, S; Maruyama, Y; Koiwa, Y; Ishide, N; Kitaoka, S; Tamaki, K; Sato, S; Shimizu, Y; Ino-Oka, E; Takishima, T

1981-09-01

235

Monitoring during paediatric cardiac anaesthesia  

Microsoft Academic Search

Monitoring of paediatric anaesthesia has become increasingly more complex in recent years and this is particulary true of\\u000a cardiac anaesthesia. The purpose of this review is to give a comprehensive update of published material related to both routine\\u000a and specialized cardiac monitoring. Routine monitoring can be particularly affected by the alterations of cardiac rhythm,\\u000a blood flow, cardiac output and oxygenation

Jonathan P. Purday

1994-01-01

236

Are Output Fluctuations Transitory?  

Microsoft Academic Search

According to the conventional view of the business cycle, fluctuations in output represent temporary deviations from trend. The purpose of this paper is to question this conventional view. If fluctuations in output are dominated by temporary deviations from the natural rate of output, then an unexpected change in output today should not substantially change one's forecast of output in, say,

John Y. Campbell; N. Gregory Mankiw

1987-01-01

237

Exceptional cardiac anoxia tolerance in tilapia (Oreochromis hybrid).  

PubMed

Anoxic survival requires the matching of cardiac ATP supply (i.e. maximum glycolytic potential, MGP) and demand (i.e. cardiac power output, PO). We examined the idea that the previously observed in vivo downregulation of cardiac function during exposure to severe hypoxia in tilapia (Oreochromis hybrid) represents a physiological strategy to reduce routine PO to within the heart's MGP. The MGP of the ectothermic vertebrate heart has previously been suggested to be ?70 nmol ATP s(-1) g(-1), sustaining a PO of ?0.7 mW g(-1) at 15°C. We developed an in situ perfused heart preparation for tilapia (Oreochromis hybrid) and characterized the routine and maximum cardiac performance under both normoxic (>20 kPa O(2)) and severely hypoxic perfusion conditions (<0.20 kPa O(2)) at pH 7.75 and 22°C. The additive effects of acidosis (pH 7.25) and chemical anoxia (1 mmol l(-1) NaCN) on cardiac performance in severe hypoxia were also examined. Under normoxic conditions, cardiac performance and myocardial oxygen consumption rate were comparable to those of other teleosts. The tilapia heart maintained a routine normoxic cardiac output (Q) and PO under all hypoxic conditions, a result that contrasts with the hypoxic cardiac downregulation previously observed in vivo under less severe conditions. Thus, we conclude that the in vivo downregulation of routine cardiac performance in hypoxia is not needed in tilapia to balance cardiac energy supply and demand. Indeed, the MGP of the tilapia heart proved to be quite exceptional. Measurements of myocardial lactate efflux during severe hypoxia were used to calculate the MGP of the tilapia heart. The MGP was estimated to be 172 nmol ATP s(-1) g(-1) at 22°C, and allowed the heart to generate a PO(max) of at least ?3.1 mW g(-1), which is only 30% lower than the PO(max) observed with normoxia. Even with this MGP, the additional challenge of acidosis during severe hypoxia decreased maximum ATP turnover rate and PO(max) by 30% compared with severe hypoxia alone, suggesting that there are probably direct effects of acidosis on cardiac contractility. We conclude that the high maximum glycolytic ATP turnover rate and levels of PO, which exceed those measured in other ectothermic vertebrate hearts, probably convey a previously unreported anoxia tolerance of the tilapia heart, but a tolerance that may be tempered in vivo by the accumulation of acidotic waste during anoxia. PMID:22442374

Lague, Sabine L; Speers-Roesch, Ben; Richards, Jeffrey G; Farrell, Anthony P

2012-04-15

238

The hemodynamics of cardiac tamponade.  

PubMed

The changes produced by acute pericardial tamponade were examined. Tamponade produced the expected hemodynamic alteration; namely, depression on cardiac output, left ventricular pressure and LV dp/dt and elevation of right atrial and intrapericardial pressures. The mechanism of the hemodynamic disturbances was that the elevation of the intrapericardial pressure produced a negative atrial transmural pressure and disturbed atrial and ventricle filling producing the vicious cycle: diminished venoatrial gradient leads to decreased cardiac output leads to attenuated effect of ventricular systole on atrial filling, and so forth. The myocardial contractility was not impaired in cardiac tamponade. PMID:642185

Nakata, Y; Takahashi, F

1978-02-01

239

Caffeine enhances doxorubicin cardiac toxicity in an animal model  

Microsoft Academic Search

Based on in vitro data suggesting an interaction between methylxanthines and doxorubicin in regulating Ca2+ across muscle sarcoplasmic reticulum, this study was designed to test the hypothesis that a commonly used methylxanthine, caffeine, might influence the cardiac toxicity of doxorubicin. Three days following doxorubicin treatment, in vivo intracardiac pressures, cardiac outputs, in vitro cardiac weights, and cardiac electron microscopy were

Jeffrey D. Hosenpud; Jay Wright; Leonard Simpson; Jonathan J. Abramson

1995-01-01

240

Functional significance of coactivation of vagal and sympathetic cardiac nerves.  

PubMed Central

Simultaneous recording of activity in the vagal and sympathetic supplies to the heart has revealed that in reflexly and centrally evoked activity these two "antagonists" do not necessarily change action reciprocally. Coactivation occurs in chemoreceptor reflexes and related reactions, upon stretching of the sinoatrial nodal region of the right atrium and when certain hypothalamic regions are stimulated. The objective of the present work was to assay the physiological importance of coactivation of the two potentially antagonistic cardiac nerves in anesthetized dogs. Output from the heart was monitored by recording volume flow in the thoracic aorta just below the aortic arch; cardiac contractility was measured as left ventricular dp/dt. Tape recordings of vagus and sympathetic nerve activity during chemoreceptor and baroreceptor reflexes, during reciprocal and nonreciprocal changes produced by hypothalamic stimulation, and during hypoxia and hypercapnia were used to trigger stimulators feeding a stimulus per action potential to cardiac vagus and sympathetic nerves after central connections were cut. The vagus stimulation alone produced a decrease in aortic blood flow; stimulation of the sympathetic nerve alone resulted in increased aortic blood flow. Simultaneous stimulation of vagus and sympathetic, however, produced an even greater cardiac output (measured by aortic blood flow). Intermediate degrees of heart rate and strength of myocardial contraction were maintained in coactivation. Obviously, an association of increased vagus and sympathetic actions, which can be effected reflexly or by action of higher centers, is of physiological benefit. In control reactions that relate cardiac function to body need, both reciprocal and synergistic actions (coactivation) of cardiac nerves are used. Images

Koizumi, K; Terui, N; Kollai, M; Brooks, C M

1982-01-01

241

Changes in caridac output and hemolymph flow during hypoxic exposure in the gravid grass shrimp, Palaemonetes pugio.  

PubMed

The cardiovascular response of decapod crustaceans to hypoxic exposure is well documented; however, information is limited concerning the influence of reproductive state on cardiovascular demands during hypoxic exposure. Given the additional metabolic demand of reproduction, we investigated the cardiovascular adjustments employed by gravid grass shrimp Palaemonetes pugio to maintain oxygen delivery during hypoxic stress. Cardiac output values were elevated in gravid compared to nongravid grass shrimp. Gravid grass shrimp were exposed to hypoxia and the stroke volume, heart rate, cardiac output and hemolymph flow were determined using video-microscopy and dimensional analysis. Oxygen consumption rates were determined using respirometry. There where no changes in the cardiac output values of gravid females until reaching 6.8 kPa O2, with a significant redistribution of hemolymph flow at 13.7 kPa O2. Flow was significantly decreased to the anterior lateral arteries that supply the ovaries and hepatopancreas, the anterior aorta and the posterior aorta. The redistribution of hemolymph flow away from these vessels results in an enhanced hemolymph flow to the sternal artery that supplies the ventral segmental system, the gills, the buccal apparatus and the ventral nerve cord. The data suggest that during hypoxic stress, gravid females place a priority on survival. PMID:15891889

Guadagnoli, Jutta A; Reiber, Carl L

2005-05-13

242

Generalized Radar Output Simulation.  

National Technical Information Service (NTIS)

Using the outputs from the simulation of overall body motion related to observations at a complex of earth stations, this report develops a model for generating the scattering matrix and radar output voltages. The general multistatic case is treated using...

J. F. A. Ormsby S. H. Bickel

1969-01-01

243

Polymer waveguide output coupler  

NASA Astrophysics Data System (ADS)

Waveguide output couplers fabricated in Norlund Optical Adhesive (NOA) #81 are investigated. The output coupler is implemented using periodic relief gratings on a planar waveguide. Design theory of the coupler is based ont he perturbation approach. Coupling of light from waveguide propagation modes to output radiation modes is described by coupled mode theory and the transmission line approximation of the perturbed area (grating structure). Using these concepts, gratings can be accurately designed to output a minimum number of modes at desired output angles. Waveguide couplers were designed using these concepts. The couplers were fabricated and analyzed for structural accuracy, output beam accuracy, and output efficiency. Applications for these couplers include databus and clock distribution system interfaces requiring coupling to out-of- plane detectors.

Watson, Michael D.; Abushagur, Mustafa A.; Ashley, Paul R.; Johnson-Cole, Helen

1995-09-01

244

Design and testing of an MRI-compatible cycle ergometer for non-invasive cardiac assessments during exercise  

PubMed Central

Background Magnetic resonance imaging (MRI) is an important tool for cardiac research, and it is frequently used for resting cardiac assessments. However, research into non-pharmacological stress cardiac evaluation is limited. Methods We aimed to design a portable and relatively inexpensive MRI cycle ergometer capable of continuously measuring pedalling workload while patients exercise to maintain target heart rates. Results We constructed and tested an MRI-compatible cycle ergometer for a 1.5 T MRI scanner. Resting and sub-maximal exercise images (at 110 beats per minute) were successfully obtained in 8 healthy adults. Conclusions The MRI-compatible cycle ergometer constructed by our research group enabled cardiac assessments at fixed heart rates, while continuously recording power output by directly measuring pedal force and crank rotation.

2012-01-01

245

Validation of maintainability prediction  

NASA Astrophysics Data System (ADS)

Validation of maintainability prediction techniques was performed. The techniques for preliminary and detailed predictions were applied to three (3) representative samples of electronic equipment. The detailed predictions were then compared with demonstrated field performance on equipments that have in excess of one million system hours of combined operation. The time synthesis prediction technique proved to be a distinct improvement in maintainability prediction methodology over existing techniques. In addition, the time synthesis model provides a structured means of assessing the maintainability design in its early and final stages, thereby determining if the system maintainability requirements will be achieved. The standards for removal and replacement actions were analyzed in detail and modifications recommend.

Dublanica, W.; Kubeck, J.; Edwards, E.

1982-09-01

246

Electronic Equipment Maintainability Data.  

National Technical Information Service (NTIS)

This is the first of a series of maintainability data publications at the system/equipment level. Other volumes prepared by the Reliability Analysis Center consider reliability of digital microcircuits, discrete semiconductors (including optoelectronic an...

N. B. Fuqua

1980-01-01

247

Cardiac resistance to growth hormone in uremia  

Microsoft Academic Search

Cardiac resistance to growth hormone in uremia.BackgroundCardiovascular disease is a major cause of death in end-stage renal disease (ESRD). Since growth hormone is required for maintaining normal cardiac structure and function and as growth hormone has a salutary effect on cardiac remodeling in disease, we postulated that if cardiac resistance to growth hormone develops in chronic renal failure (CRF) this

ZHILAN ZHENG; DI FEI SUN; PADMAJA TUMMALA; RALPH RABKIN

2005-01-01

248

Epo deficiency alters cardiac adaptation to chronic hypoxia.  

PubMed

The involvement of erythropoietin in cardiac adaptation to acute and chronic (CHx) hypoxia was investigated in erythropoietin deficient transgenic (Epo-TAg(h)) and wild-type (WT) mice. Left (LV) and right ventricular functions were assessed by echocardiography and hemodynamics. HIF-1?, VEGF and Epo pathways were explored through RT-PCR, ELISA, Western blot and immunocytochemistry. Epo gene and protein were expressed in cardiomyocytes of WT mice in normoxia and hypoxia. Increase in blood hemoglobin, angiogenesis and functional cardiac adaptation occurred in CHx in WT mice, allowing a normal oxygen delivery (O2T). Epo deficiency induced LV hypertrophy, increased cardiac output (CO) and angiogenesis, but O2T remained lower than in WT mice. In CHx Epo-TAg(h) mice, LV hypertrophy, CO and O2T decreased. HIF-1? and Epo receptor pathways were depressed, suggesting that Epo-TAg(h) mice could not adapt to CHx despite activation of cardioprotective pathways (increased P-STAT-5/STAT-5). HIF/Epo pathway is activated in the heart of WT mice in hypoxia. Chronic hypoxia induced cardiac adaptive responses that were altered with Epo deficiency, failing to maintain oxygen delivery to tissues. PMID:23333855

El Hasnaoui-Saadani, Raja; Marchant, Dominique; Pichon, Aurélien; Escoubet, Brigitte; Pezet, Mylène; Hilfiker-Kleiner, Denise; Hoch, Melanie; Pham, Isabelle; Quidu, Patricia; Voituron, Nicolas; Journé, Clément; Richalet, Jean-Paul; Favret, Fabrice

2013-01-16

249

Cardiac amyloidosis  

MedlinePLUS

... Primary cardiac amyloidosis - AL type; Secondary cardiac amyloidosis - AA type; Stiff heart syndrome; Senile amyloidosis ... arrhythmias and conduction disturbances (heart block). Secondary amyloidosis (AA type) rarely affects the heart. However, a form ...

250

Software Maintainability Index Revisited  

SciTech Connect

For many years now, software practitioners have been collecting metrics from source code in an effort to better understand the software they are developing or changing. Maintainability Index (MI) is a composite metric that incorporates a number of traditional source code metrics into a single number that indicates relative maintainability. As originally proposed by Oman and Hagemeister, the MI is comprised of weighted Halstead metrics (effort or volume), McCabe's Cyclomatic Complexity, lines of code (LOC), and number of comments [1, 2]. Two equations were presented: one that considered comments and one that did not.

Welker, Kurt Dean

2001-08-01

251

Visualization of Model Output  

NSDL National Science Digital Library

Visualization of output from mathematical or statistical models is one of the best ways to introduce introductory geoscience students to the results and behavior of sophisticated models. Example of good sites ...

252

What Is an Output?  

Microsoft Academic Search

A recurrent idea in the history of psychology is that one is conscious of outputs but not of the complex processes underlying the generation of outputs, which is evident in the out-of-the-blue, “eureka-like” experiences associated with intuition. We examine how this idea may suffer from a logical fallacy and may thus have inadvertently hindered progress on the study of the

Ezequiel Morsella; John A. Bargh

2010-01-01

253

Linear output nitinol engine  

SciTech Connect

This patent describes a linear output nitinol engine consisting of a number of integrated communicating parts. The engine has an external support framework which is described in detail. The patent further describes a wire transport mechanism, a pair of linkage levers with a loom secured to them, a number of nitinol wires strung between the looms, and a power takeoff block secured to the linkage levers. A pulley positioned in a flip-flop supporting bracket and a power takeoff modality including a tension member connected to a power output cable in order to provide linear power output transmission is described. A method for biasing the timing and the mechanism for timing the synchronization of the throw over arms and the flip-flop of the pulley are also described.

Banks, R.M.

1986-01-14

254

Critical care of the cardiac patient.  

PubMed

As the spectrum of cardiac surgeries has grown, the diversity and complexity of postoperative cardiac surgical care has also increased. This article examines 4 areas in critical care where clinical practice is evolving rapidly. Among these are management of mechanical ventilation, thresholds for blood transfusion, strategies for hemodynamic monitoring, and processes for central line insertion. Also reviewed are current approaches to common dilemmas in postoperative cardiac care: diagnosis of tamponade, and the diagnosis and management of low cardiac output states in patients with a ventricular assist device. PMID:23711651

Tung, Avery

2013-02-09

255

Cardiac sarcoidosis.  

PubMed

Cardiac sarcoidosis is a rare entity and may be difficult to diagnose prior to cardiac surgery. We review the imaging and diagnostic studies necessary to make the diagnosis and discuss therapeutic algorithms to manage this disease. doi: 10.1111/jocs.12163 (J Card Surg 2013;28:525-528). PMID:23844704

Zacek, Pavel; Omran, Nedal; Chek, James L; Krbal, Lukas; Vojacek, Jan; Harrer, Jan

2013-07-12

256

Generalized multirate-output controllers  

Microsoft Academic Search

This paper studies controllers employing multirate sampling of the plant output (Hagiwara and Araki 1988 a). Specifically, it is shown that arbitrary pole assignment is possible by a multirate output sampling mechanism with smaller output multiplicities if a multiframe control law is introduced. We refer to the new control law as the generalized multirate-output controller. It is also shown that

TOMOMICHI HAGIWARA; TOSHIFUMI FUJIMURA; MITUHIKO ARAKI

1990-01-01

257

[Cardiac radiology].  

PubMed

From the beginning of the era of X-rays, cardiac radiology has become a target of this new technique. Early pioneers, Ciegem, Rieder, Rosenthal, Williams rapidly accumulated extensive experience with fluoroscopy and radiography and publications on cardiac diseases as soon as 1899 and 1901 and 1902. The next step in cardiac diagnosis was achieved by Forsmann in 1929, with the first attempt at cardiac catheterization and angiocardiography. Many clinicians, Moniz, Reboul, Rousthoi contributed to the development of the technique between 1930 and 1940. A further turning point came in 1941 when Cournand demonstrated that cardiac catheterization was a safe method in man. In the technical field major progress came from Scandinavia were rapid filming was born. The management of ischaemic disease, changed dramatically with the demonstration of coronary anatomy, largely due to Sones, Judkins and Amplatz. A further progress was initiated in 1977 by Gruentzig who invented balloon angioplasty. PMID:8550395

Struyven, J

1995-10-01

258

A Time-Cycled External Cardiac Compressor.  

National Technical Information Service (NTIS)

During cardiac arrest, the flow of oxygenated blood to the brain becomes insufficient to support life. With new methods of cardiopulmonary resuscitation, blood circulation can be maintained, the heart restarted, normal circulation resumed, and the patient...

J. W. Joyce G. Mon

1968-01-01

259

Cardiac mechanoenergetic cost of elevated plasma viscosity after moderate hemodilution.  

PubMed

The purpose of this study was to investigate how plasma viscosity affects cardiac and vascular function during moderate hemodilution. Twelve anesthetized hamsters were hemodiluted by 40% of blood volume with two different viscosity plasma expanders. Experimental groups were based on the plasma expander viscosity, namely: high viscosity plasma expander (HVPE, 6.3 mPa?·?s) and low viscosity plasma expander (LVPE, 2.2 mPa?·?s). Left ventricular (LV) function was intracardiacally measured with a high temporal resolution miniaturized conductance catheter and concurrent pressure-volume results were used to calculate different LV indices. Independently of the plasma expander, hemodilution decreased hematocrit to 28% in both groups. LVPE hemodilution reduced whole blood viscosity by 40% without changing plasma viscosity, while HVPE hemodilution reduced whole blood viscosity by 23% and almost doubled plasma viscosity relative to baseline. High viscosity plasma expander hemodilution significantly increased cardiac output, stroke volume and stroke work compared to baseline, whereas LVPE hemodilution did not. Furthermore, an increase in plasma viscosity during moderate hemodilution produced a higher energy transfer per unit volume of ejected blood. Systemic vascular resistance decreased after hemodilution in both groups. Counter-intuitively, HVPE hemodilution showed lower vascular resistance and vascular hindrance than LVPE hemodilution. This result suggests that geometrical changes in the circulatory system are induced by the increase in plasma viscosity. In conclusion, an increase in plasma viscosity after moderate hemodilution directly influenced cardiac and vascular function by maintaining hydraulic power and reducing systemic vascular resistance through vasodilation. PMID:21084746

Chatpun, Surapong; Cabrales, Pedro

2010-01-01

260

Cardiac catheterization and angiography, 3d Ed  

SciTech Connect

This textbook was first published in 1974 and subsequently revised in 1980. The current edition, in seven parts and 33 chapters, has been extensively rewritten, and new chapters have been added that present recently developed techniques. The references have been updated to 1985. The purpose of this work is to provide a concise description of the major techniques employed in cardiac catheterization and angiography. Part 1 deals with the history, general principles, and practice of cardiac catheterization and angiography. In part 2, various techniques of cardiac catheterization are discussed and compared. In part 3, techniques for the determination of cardiac output, pressure, resistance, valve area, and shunt flow are described. Part 4 deals briefly with coronary angiography, cardiac ventriculography, pulmonary angiography, and aortography. In part 5, techniques for evaluating cardiac function and intracardiac electrophysiology are presented. The characteristic hemodynamic and angiographic abnormalities in specific disorders are described in part 6. Part 7 deals with special catheter techniques.

Grossman, W.

1986-01-01

261

Maintainability Engineering Design Notebook, Revision II, and Cost of Maintainability.  

National Technical Information Service (NTIS)

This chapter contains a detailed description of the tasks required to develop a maintainability demonstration plan, with guidelines and methodology for preparing the plan, test methods that are used in maintainability demonstration tests, procedures for p...

L. R. Greenman

1975-01-01

262

Cardiac Output, Rates of Change and Accumulation: Unit Overview  

NSDL National Science Digital Library

Created by Illuminations: Resources for Teaching Mathematics, this unit plan contains four lessons that explore rates of change and accumulation in the context of the amount of blood being pumped by the heart. The measurement is done from a discrete perspective, but can be easily generalized to a continuous perspective that includes use of integral calculus. The individual lessons are titled: make a conjecture, gather data, analyze the data and reflecting on your work. The author states the goal of this lesson as: "[The] rich exploration of rates of change and accumulation in context."

2009-02-23

263

Cardiac Regenerative Capacity and Mechanisms  

PubMed Central

The heart holds the monumental yet monotonous task of maintaining circulation. Although cardiac function is critical to other organs and to life itself, mammals are not equipped with significant natural capacity to replace heart muscle that has been lost by injury. This deficiency plays a role in leaving millions worldwide each year vulnerable to heart failure. By contrast, certain other vertebrate species like zebrafish are strikingly good at heart regeneration. A cellular and molecular understanding of endogenous regenerative mechanisms, combined with advances in methodology to transplant cells, together project a future in which cardiac muscle regeneration can be therapeutically stimulated in injured human hearts. This review will focus on what has been discovered recently about cardiac regenerative capacity and how natural mechanisms of heart regeneration in model systems are stimulated and maintained.

Kikuchi, Kazu; Poss, Kenneth D.

2013-01-01

264

The cardiac valve interstitial cell  

Microsoft Academic Search

Cardiac valve interstitial cells (ICs) are a heterogeneous and dynamic population of specific cell types that have many unique characteristics. They are responsible for maintaining the extracellular scaffold that provides the mechanical characteristics vital for sustaining the unique dynamic behaviour of the valve. A number of cellular phenotypes can be distinguished: some are sparsely arranged throughout the valve leaflets, whilst

Patricia M Taylor; Puspa Batten; Nigel J Brand; Penny S Thomas; Magdi H Yacoub

2003-01-01

265

Cardiac Arrest  

MedlinePLUS

... too slow, or it can stop beating. Sudden cardiac arrest (SCA) occurs when the heart develops an arrhythmia that ... is blocked. There are many possible causes of SCA. They include coronary heart disease, physical stress, and ...

266

Engine Maintainability: Objectives and Methods.  

National Technical Information Service (NTIS)

Major considerations used to improve engine maintainability are identified. The basis for maintainability features are a lot of requirements. These requirements are defined by the customer and created using several analyses. Criteria for good maintainabil...

A. Senft

1989-01-01

267

Cardiac cameras.  

PubMed

Cardiac imaging with radiotracers plays an important role in patient evaluation, and the development of suitable imaging instruments has been crucial. While initially performed with the rectilinear scanner that slowly transmitted, in a row-by-row fashion, cardiac count distributions onto various printing media, the Anger scintillation camera allowed electronic determination of tracer energies and of the distribution of radioactive counts in 2D space. Increased sophistication of cardiac cameras and development of powerful computers to analyze, display, and quantify data has been essential to making radionuclide cardiac imaging a key component of the cardiac work-up. Newer processing algorithms and solid state cameras, fundamentally different from the Anger camera, show promise to provide higher counting efficiency and resolution, leading to better image quality, more patient comfort and potentially lower radiation exposure. While the focus has been on myocardial perfusion imaging with single-photon emission computed tomography, increased use of positron emission tomography is broadening the field to include molecular imaging of the myocardium and of the coronary vasculature. Further advances may require integrating cardiac nuclear cameras with other imaging devices, ie, hybrid imaging cameras. The goal is to image the heart and its physiological processes as accurately as possible, to prevent and cure disease processes. PMID:21440695

Travin, Mark I

2011-05-01

268

Dipyridamole cardiac imaging  

SciTech Connect

Dipyridamole cardiac imaging is a useful alternative technique to exercise stress testing in the evaluation of patients with ischemic heart disease. Intravenous dipyridamole is still in the investigational phase, while oral dipyridamole is widely available. The hemodynamic effects of dipyridamole include an increase in coronary blood flow (due to coronary vasodilation) which is in excess of the increase in myocardial oxygen consumption and cardiac output. The disparity in the increase in coronary blood flow relative to the cardiac output results in an increase in myocardial thallium activity and an increase in the myocardial/background activity ratio. The quality of the thallium images is better or similar to that of exercise thallium images. The optimal dose of intravenous dipyridamole is 0.56 mg/kg, and of the oral dose it is 300 to 400 mg, although higher doses may be necessary in some patients. Analysis of the thallium images has been to a large extent based on visual inspection of the planar images. Delayed images are helpful to establish the nature of the perfusion abnormalities (transient or fixed). The process of redistribution is based on disparate rates of washout from the normal and abnormal zones. The sensitivity and specificity of dipyridamole thallium imaging, whether intravenous or oral, have been shown in a number of studies to be quite adequate and comparable to that achieved during exercise thallium imaging. Dipyridamole two-dimensional echocardiography has also been used in the detection of coronary artery disease; transient (new or worsening of preexisting) wall motion abnormalities have been found to be a specific marker of coronary artery disease. Transmural as well as regional coronary steal phenomena have been postulated as the mechanism for dipyridamole-induced regional wall motion abnormalities. 65 references.

Iskandrian, A.S.; Heo, J.; Askenase, A.; Segal, B.L.; Auerbach, N.

1988-02-01

269

X-ray source assembly having enhanced output stability, and fluid stream analysis applications thereof  

Microsoft Academic Search

An x-ray source assembly and method of operation are provided having enhanced output stability. The assembly includes an anode having a source spot upon which electrons impinge and a control system for controlling position of the anode source spot relative to an output structure. The control system can maintain the anode source spot location relative to the output structure notwithstanding

Ian Radley; Thomas J. Bievenue; John H. Burdett; Brian W. Gallagher; Stuart M. Shakshober; Zewu Chen; Michael D. Moore

2008-01-01

270

Cardiac disease and cognitive impairment: a systematic review.  

PubMed

Cognitive impairment in cardiac patients may interfere with disease management. This review describes studies examining specific cognitive impairments in cardiac patients and studies that investigate the link between echocardiographic and cognitive measures. Executive function impairments were frequently reported in different patient groups. Also, lower cardiac output and worse left ventricular diastolic function are linked to executive function deficits. In cardiac patients, special attention should be paid to these executive function impairments in view of their role in disease management and independent living. Interventions that stimulate executive function should be encouraged and integrated in cardiac treatment protocols. PMID:22689718

Eggermont, Laura H P; de Boer, Karin; Muller, Majon; Jaschke, Artur C; Kamp, Otto; Scherder, Erik J A

2012-06-11

271

Cardiac syncope.  

PubMed

Clinicians who diagnose and manage epilepsy frequently encounter diagnoses of a nonneurological nature, particularly when assessing patients with transient loss of consciousness (T-LOC). Among these, and perhaps the most important, is cardiac syncope. As a group, patients with cardiac syncope have the highest likelihood of subsequent sudden death, and yet, unlike sudden unexpected death in epilepsy (SUDEP) for example, it is the norm for these tragic occurrences to be both easily predictable and preventable. In the 12 months following initial presentation with cardiac syncope, sudden death has been found to be 6 times more common than in those with noncardiac syncope (N Engl J Med 309, 1983, 197). In short, for every patient seen with T-LOC, two fundamental aims of the consultation are to assess the likelihood of cardiac syncope as the cause, and to estimate the risk of future sudden death for the individual. This article aims to outline for the noncardiologist how to recognize cardiac syncope, how to tell it apart from more benign cardiovascular forms of syncope as well as from seizures and epilepsy, and what can be done to predict and prevent sudden death in these patients. This is achieved through the assessment triad of a clinical history and examination, risk stratification, and 12-lead electrocardiography (ECG). PMID:23153208

Anderson, Joseph; O'Callaghan, Peter

2012-12-01

272

Hemodynamic Effects of Calcium Antagonists in Cardiac Patients  

Microsoft Academic Search

Hemodynamic studies were carried out after cardiac catheterization with a floatation catheter in the pulmonary artery and cannulation of the brachial artery for the calculation of cardiac output by means of the Fick principle. Continuous pressure recordings were carried out at rest and under submaximal treadmill exercise in the supine body position in 5 homogeneous groups of 12 patients, all

H. Pozenel

1982-01-01

273

Cardiac emergencies.  

PubMed

The diagnosis and management of pediatric cardiac emergencies can be challenging and complicated. Early presentations are usually the result of ductal-dependent lesions and appear with cyanosis and shock. Later presentations are the result of volume overload or pump failure and present with signs of congestive heart failure. Acquired diseases also present as congestive heart failure or arrhythmias. PMID:23915599

Barata, Isabel Araujo

2013-08-01

274

Serial Input Output  

SciTech Connect

Serial Input/Output (SIO) is designed to be a long term storage format of a sophistication somewhere between simple ASCII files and the techniques provided by inter alia Objectivity and Root. The former tend to be low density, information lossy (floating point numbers lose precision) and inflexible. The latter require abstract descriptions of the data with all that that implies in terms of extra complexity. The basic building blocks of SIO are streams, records and blocks. Streams provide the connections between the program and files. The user can define an arbitrary list of streams as required. A given stream must be opened for either reading or writing. SIO does not support read/write streams. If a stream is closed during the execution of a program, it can be reopened in either read or write mode to the same or a different file. Records represent a coherent grouping of data. Records consist of a collection of blocks (see next paragraph). The user can define a variety of records (headers, events, error logs, etc.) and request that any of them be written to any stream. When SIO reads a file, it first decodes the record name and if that record has been defined and unpacking has been requested for it, SIO proceeds to unpack the blocks. Blocks are user provided objects which do the real work of reading/writing the data. The user is responsible for writing the code for these blocks and for identifying these blocks to SIO at run time. To write a collection of blocks, the user must first connect them to a record. The record can then be written to a stream as described above. Note that the same block can be connected to many different records. When SIO reads a record, it scans through the blocks written and calls the corresponding block object (if it has been defined) to decode it. Undefined blocks are skipped. Each of these categories (streams, records and blocks) have some characteristics in common. Every stream, record and block has a name with the condition that each stream, record or block name must be unique in its category (i.e. all streams must have different names, but a stream can have the same name as a record). Each category is an arbitrary length list which is handled by a 'manager' and there is one manager for each category.

Waite, Anthony; /SLAC

2011-09-07

275

TNF? may partially mediate the cardiac effects of parathyroid hypertensive factor  

Microsoft Academic Search

Previous studies have demonstrated that Parathyroid Hypertensive Factor (PHF) influences blood pressure through effects on both peripheral vascular resistance and cardiac output. In terms of cardiac effects, PHF has been shown to affect cardiac contractility through a variety of mechansisms including sympthetic stimulation, endocardial NO generation and direct myocardial effects. As TNF? can stimulate endocardial NO generation, the purpose of

Richard Z. Lewanczuk; Christina G. Benishin

2001-01-01

276

Output Growth Volatility and Remittances  

Microsoft Academic Search

Output growth volatility has negative effects on growth, poverty and welfare. The empirical literature has therefore searched for country?specific factors affecting volatility and focused on financial development, policy distortions, trade and financial openness. Using the same empirical framework, we focus on migrants' remittances that can help to reduce output growth volatility thanks to their size, stability and low procyclicality. In

MATTEO BUGAMELLI

2011-01-01

277

Quantifying PV power Output Variability  

Microsoft Academic Search

This paper presents a novel approach to rigorously quantify power Output Variability from a fleet of photovoltaic (PV) systems, ranging from a single central station to a set of distributed PV systems. The approach demonstrates that the relative power Output Variability for a fleet of identical PV systems (same size, orientation, and spacing) can be quantified by identifying the number

Thomas E. Hoff; Richard Perez

2010-01-01

278

Noninvasive monitoring of transient cardiac changes with impedance cardiography.  

PubMed

Impedance cardiography (IC) has been used to monitor the pumping function of the heart in terms of stroke volume or cardiac output. We explored the extent to which IC can be used for monitoring transient effects of cardiac alterations on a beat-to-beat basis. A four-spot-electrode configuration was used in the present design. The spatial arrangement of the four electrodes was carefully selected to obtain an optimal result. A constant current source provided a 4 mA, 20 kHz sinusoidal excitation current. Analog signal processing was developed to demodulate and amplify the resultant impedance information, eliminate low frequency motion artifacts and incidental breathing artifacts. Experiments were performed on normal healthy volunteers. Impedance waveforms were recorded from each subject beginning from a supine position then moving to an upright position. Breath holding was maintained throughout the procedure. The impedance waveform, Z, its first derivative dZ/dt, the DC component, Z(0), and electrocardiogram were recorded simultaneously and continuously. The results showed a significant increase in the relative impedance levels from supine to transient state and then decreased during the upright position. Additionally, the supine position had a higher (dZ/dt)(max) than sitting resulting in a reduction in stroke volume. The increased impedance from supine to sitting verified the physiological findings obtained by others. The results of this investigation illustrate the ability of impedance cardiography to effectively monitor the dynamic cardiovascular function under transient conditions. PMID:19130223

Zhang, Hongjun; Li, John K-J

2008-12-01

279

Enhanced performance CCD output amplifier  

DOEpatents

A low-noise FET amplifier is connected to amplify output charge from a che coupled device (CCD). The FET has its gate connected to the CCD in common source configuration for receiving the output charge signal from the CCD and output an intermediate signal at a drain of the FET. An intermediate amplifier is connected to the drain of the FET for receiving the intermediate signal and outputting a low-noise signal functionally related to the output charge signal from the CCD. The amplifier is preferably connected as a virtual ground to the FET drain. The inherent shunt capacitance of the FET is selected to be at least equal to the sum of the remaining capacitances.

Dunham, Mark E. (Los Alamos, NM); Morley, David W. (Santa Fe, NM)

1996-01-01

280

Neurons within the same network independently achieve conserved output by differentially balancing variable conductance magnitudes.  

PubMed

Biological and theoretical evidence suggest that individual neurons may achieve similar outputs by differentially balancing variable underlying ionic conductances. Despite the substantial amount of data consistent with this idea, a direct biological demonstration that cells with conserved output, particularly within the same network, achieve these outputs via different solutions has been difficult to achieve. Here we demonstrate definitively that neurons from native neural networks with highly similar output achieve this conserved output by differentially tuning underlying conductance magnitudes. Multiple motor neurons of the crab (Cancer borealis) cardiac ganglion have highly conserved output within a preparation, despite showing a 2-4-fold range of conductance magnitudes. By blocking subsets of these currents, we demonstrate that the remaining conductances become unbalanced, causing disparate output as a result. Therefore, as strategies to understand neuronal excitability become increasingly sophisticated, it is important that such variability in excitability of neurons, even among those within the same individual, is taken into account. PMID:23761890

Ransdell, Joseph L; Nair, Satish S; Schulz, David J

2013-06-12

281

Is levosimendan effective in paediatric heart failure and post-cardiac surgeries?  

PubMed

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was 'do children with heart failure post-cardiac surgery undergoing treatment with levosimendan have an acceptable haemodynamic improvement?' The use of levosimendan as a vasoactive drug is an accepted intervention for patients with altered haemodynamics post-cardiac surgeries. However, the role of levosimendan and its efficacy have been debated. Eleven relevant papers were identified, which represented the best evidence to answer the question. The author, journal, date, country of publication and relevant outcomes are tabulated. The 11 studies comprised 3 randomized trials, 2 of which compared levosimendan and milrinone. A single-centre randomized study that included 40 infants showed that cardiac output (CO) and cardiac index (CI) increased overtime in the levosimendan group compared with the milrinone group. The significant interaction for CO (P = 0.005) and CI (P = 0.007) indicated different time courses in the two groups. A similar, European randomized study undertaken on neonates (n = 63) showed better lactate levels [P = 0.015 (intensive care admission); P = 0.048 (after 6 h) with low inotropic scores in the levosimendan group. Although the length of mechanical ventilation and mortality were less, this was statistically insignificant. A retrospective cohort analysis (n = 13) in children reported a reduced use of dobutamine and improvement in the ejection fraction from 29.8 to 40.5% (P = 0.015) with the use of levosimendan. In a questionnaire-based study from Finland, 61.1% of respondents felt that it had saved the lives of some children when the other treatments had failed. No study reported any adverse effect attributable to use of levosimendan. In conclusion, the above studies were in favour of levosimendan as a safe and feasible drug providing potential clinical benefit in low cardiac output syndrome (LCOS) and post-cardiac surgeries when other vasoactive drugs were insufficient to maintain stable haemodynamics. A small sample size was indeed a limitation in all the above studies. Furthermore, it is best used as a rescue drug on a named-patient basis. A small sample size was indeed a limitation in all the above studies. Larger, well-designed trials are required to further evaluate the efficacy and feasibility of levosimendan in paediatric heart failure and post-cardiac surgeries. PMID:23832921

Angadi, Ullas; Westrope, Claire; Chowdhry, Mohammed F

2013-07-06

282

Cardiac tamponade.  

PubMed Central

Cardiac tamponade is a cardiological emergency requiring prompt treatment in order to avoid a fatal outcome. It can complicate a number of medical conditions and it is important, therefore, that all practitioners are aware of its presentation, diagnosis and management. These are outlined. We suggest that, with certain specific and important exceptions, percutaneous catheter pericardiocentesis is to be recommended in the management of cardiac tamponade. We include a review of 51 consecutive cases treated at our own institution. Catheter pericardiocentesis was successful in 49 (96%) cases and 36 (80%) patients did not require any further intervention. There were no major and only two minor complications which required no additional treatment. We review previous literature concerning percutaneous pericardiocentesis. Using recommended procedures, pericardiocentesis is successful in 90-100% of cases and major complications are rare. Images Figure 1 Figure 2 Figure 3

Ball, J. B.; Morrison, W. L.

1997-01-01

283

Using Incentives to Improve Maintainability.  

National Technical Information Service (NTIS)

The objective of this thesis was to determine if contract incentives were appropriate for use in Dept. of Defense contracts for the purpose of motivating defense contractors to improve the maintainability of weapon systems under design. To accomplish the ...

L. Farnen

1984-01-01

284

Sonographic assessment of fetal cardiac function: introduction and direct measurement of cardiac function.  

PubMed

Noninvasive blood flow measurements based on Doppler ultrasound studies are the main clinical tool for studying the cardiovascular status in fetuses at risk for circulatory compromise. Usually, qualitative analysis of peripheral arteries and, in particular clinical situations such as severe growth restriction or volume overload, also of venous vessels close to the heart or of flow patterns in the heart are being used to gauge the level of compensation in a fetus. Quantitative assessment of the driving force of the fetal circulation, the cardiac output, however, remains an elusive goal in fetal medicine. This article reviews the methods for direct and indirect assessment of cardiac function and explains new clinical applications. Part 1 of this review describes the concept of cardiac function and cardiac output and the techniques that have been used to quantify output. Part 2 summarizes the use of arterial and venous Doppler studies in the fetus and gives a detailed description of indirect measures of cardiac function (like indices derived from the duration of segments of the cardiac cycle) with current examples of their application. PMID:21614744

Tutschek, B; Schmidt, K G

2011-05-25

285

Cardiac optogenetics.  

PubMed

Optogenetics is an emerging technology for optical interrogation and control of biological function with high specificity and high spatiotemporal resolution. Mammalian cells and tissues can be sensitized to respond to light by a relatively simple and well-tolerated genetic modification using microbial opsins (light-gated ion channels and pumps). These can achieve fast and specific excitatory or inhibitory response, offering distinct advantages over traditional pharmacological or electrical means of perturbation. Since the first demonstrations of utility in mammalian cells (neurons) in 2005, optogenetics has spurred immense research activity and has inspired numerous applications for dissection of neural circuitry and understanding of brain function in health and disease, applications ranging from in vitro to work in behaving animals. Only recently (since 2010), the field has extended to cardiac applications with less than a dozen publications to date. In consideration of the early phase of work on cardiac optogenetics and the impact of the technique in understanding another excitable tissue, the brain, this review is largely a perspective of possibilities in the heart. It covers the basic principles of operation of light-sensitive ion channels and pumps, the available tools and ongoing efforts in optimizing them, overview of neuroscience use, as well as cardiac-specific questions of implementation and ideas for best use of this emerging technology in the heart. PMID:23457014

Entcheva, Emilia

2013-03-01

286

Cardiac Surgery  

PubMed Central

Well into the first decades of the 20th century, medical opinion held that any surgical attempts to treat heart disease were not only misguided, but unethical. Despite such reservations, innovative surgeons showed that heart wounds could be successfully repaired. Then, extracardiac procedures were performed to correct patent ductus arteriosus, coarctation of the aorta, and tetralogy of Fallot. Direct surgery on the heart was accomplished with closed commissurotomy for mitral stenosis. The introduction of the heart-lung machine and cardiopulmonary bypass enabled the surgical treatment of other congenital and acquired heart diseases. Advances in aortic surgery paralleled these successes. The development of coronary artery bypass grafting greatly aided the treatment of coronary heart disease. Cardiac transplantation, attempts to use the total artificial heart, and the application of ventricular assist devices have brought us to the present day. Although progress in the field of cardiovascular surgery appears to have slowed when compared with the halcyon times of the past, substantial challenges still face cardiac surgeons. It can only be hoped that sufficient resources and incentive can carry the triumphs of the 20th century into the 21st. This review covers past developments and future opportunities in cardiac surgery.

Weisse, Allen B.

2011-01-01

287

Regulation of the cardiac sodium pump.  

PubMed

In cardiac muscle, the sarcolemmal sodium/potassium ATPase is the principal quantitative means of active transport at the myocyte cell surface, and its activity is essential for maintaining the trans-sarcolemmal sodium gradient that drives ion exchange and transport processes that are critical for cardiac function. The 72-residue phosphoprotein phospholemman regulates the sodium pump in the heart: unphosphorylated phospholemman inhibits the pump, and phospholemman phosphorylation increases pump activity. Phospholemman is subject to a remarkable plethora of post-translational modifications for such a small protein: the combination of three phosphorylation sites, two palmitoylation sites, and one glutathionylation site means that phospholemman integrates multiple signaling events to control the cardiac sodium pump. Since misregulation of cytosolic sodium contributes to contractile and metabolic dysfunction during cardiac failure, a complete understanding of the mechanisms that control the cardiac sodium pump is vital. This review explores our current understanding of these mechanisms. PMID:22955490

Fuller, W; Tulloch, L B; Shattock, M J; Calaghan, S C; Howie, J; Wypijewski, K J

2012-09-07

288

Using a human cardiovascular-respiratory model to characterize cardiac tamponade and pulsus paradoxus  

Microsoft Academic Search

BACKGROUND: Cardiac tamponade is a condition whereby fluid accumulation in the pericardial sac surrounding the heart causes elevation and equilibration of pericardial and cardiac chamber pressures, reduced cardiac output, changes in hemodynamics, partial chamber collapse, pulsus paradoxus, and arterio-venous acid-base disparity. Our large-scale model of the human cardiovascular-respiratory system (H-CRS) is employed to study mechanisms underlying cardiac tamponade and pulsus

Deepa Ramachandran; Chuan Luo; Tony S Ma; John W Clark Jr

2009-01-01

289

Carbon dioxide and large volume ventilation in the management of patients undergoing cardiac surgery  

Microsoft Academic Search

Summary  Respiratory alkalosis produced by ippb in patients undergoing cardiothoracic surgery may reduce cardiac output, facilitate\\u000a the induction of cardiac arrhythmias, induce digitalis toxitity, decrease cerebral blood flow and shift the oxyhaemoglobin\\u000a dissociation curve to the left. These effects are most threatening in patients undergoing cardiac surgery whose cardiac reserve\\u000a is poor and whose myoeardial irritability is enhanced. This study was

Barbara Lipton; Melvin Kahn

1972-01-01

290

Output optics for laser velocimeters  

NASA Astrophysics Data System (ADS)

Space savings are effected in the optical output system of a laser velocimeter. The output system is comprised of pairs of optical fibers having output ends from which a beam of laser light emerges, a transfer lens for each light beam, and at least one final (LV) lens for receiving the light passing through the transfer lenses and for focussing that light at a common crossing point or area. In order to closely couple the transfer lenses to the final lens, each transfer lens is positioned relative to the final lens receiving light therefrom such that the output waist of the corresponding beam received by the final lens from the transfer lens is a virtual waist located before the transfer lens.

Lynch, Dana H.; Gunter, William D.; McAlister, Kenneth W.

1993-11-01

291

China: output grows with modernization  

Microsoft Academic Search

In 1978, China's coal mining industry achieved an output of 618,000,000 metric tons of raw hard coal, an increase of 128,000,000 tons compared with 1977. This has been achieved primarily by increased new mine development and the modernizaion and expansion of existing mines. While 96% of China's coal is currently produced from underground mines, only 33% of this output is

Dorling

1979-01-01

292

Improving plant and machinery maintainability.  

PubMed

The maintenance of plant and equipment is costly and can be arduous and hazardous; and yet very little ergonomics attention has been directed to these jobs and, in particular, to designing machines to be safely and speedily maintained. A new maintainability index has been developed and assessed in the UK mining industry. By applying the index the attention of ergonomists and engineers can be focused on those maintenance tasks and ergonomics factors which score high on safety and performance. Improved designs can then be synthesized using the index and assessed for their impact on machine availability. The index can also be used in product selection. PMID:15676755

Mason, S

1990-03-01

293

Cardiac pacing.  

PubMed

The basic electrophysiology of temporary and permanent cardiac pacing is reviewed, as are the indications, the types of pacing systems, and the methods of implantation. Recent developments in power sources and leads are described. The mercury-zinc battery is now obsolete and is being replaced by lithium, rechargeable, and isotopic power systems. While ventricular pacing continues to be the standard, a brief review of atrial programmed systems is given, including atrial pacing and atrioventricular synchronized and atrioventricular sequential pacing. Conventional pacing is aimed at the control of symptomatic bradycardia. Brief reference is made to experimental pacing systems designed to control ventricular or supraventricular tachyarrhythmias. PMID:453992

Smyth, N P

1979-03-01

294

Maintaining Sustainability for Green Schools  

ERIC Educational Resources Information Center

|The promise of sustainably designed school facilities is that they will operate more efficiently and last longer than buildings constructed in more traditional ways. But that promise comes with a big if. The payoff is delivered only if the facility managers operate and maintain the buildings in ways that adhere to sustainable strategies called…

Kennedy, Mike

2011-01-01

295

Maintaining quality in online education.  

PubMed

Higher education is adapting to new technologies and to the evolving pedagogies that accompany change. Maintaining quality begins with identifying purpose and assessing progress. Using the Sloan Consortium's quality framework, this article provides resources for measuring quality in online environments. PMID:17673781

Moore, Janet C

2007-01-01

296

Tips to Maintain Good Posture  

MedlinePLUS

Tips to Maintain Good Posture We often hear that good posture is essential for good health. We recognize poor posture when we see it formed as a result ... grasp of the importance and necessity of good posture. Why is good posture important? Good posture helps ...

297

Effects of perhexiline-induced fuel switch on the cardiac proteome and metabolome  

PubMed Central

Perhexiline is a potent anti-anginal drug used for treatment of refractory angina and other forms of heart disease. It provides an oxygen sparing effect in the myocardium by creating a switch from fatty acid to glucose metabolism through partial inhibition of carnitine palmitoyltransferase 1 and 2. However, the precise molecular mechanisms underlying the cardioprotective effects elicited by perhexiline are not fully understood. The present study employed a combined proteomics, metabolomics and computational approach to characterise changes in murine hearts upon treatment with perhexiline. According to results based on difference in-gel electrophoresis, the most profound change in the cardiac proteome related to the activation of the pyruvate dehydrogenase complex. Metabolomic analysis by high-resolution nuclear magnetic resonance spectroscopy showed lower levels of total creatine and taurine in hearts of perhexiline-treated mice. Creatine and taurine levels were also significantly correlated in a cross-correlation analysis of all metabolites. Computational modelling suggested that far from inducing a simple shift from fatty acid to glucose oxidation, perhexiline may cause complex rebalancing of carbon and nucleotide phosphate fluxes, fuelled by increased lactate and amino acid uptake, to increase metabolic flexibility and to maintain cardiac output. This article is part of a Special Issue entitled "Focus on Cardiac Metabolism".

Yin, Xiaoke; Dwyer, Joseph; Langley, Sarah R.; Mayr, Ursula; Xing, Qiuru; Drozdov, Ignat; Nabeebaccus, Adam; Shah, Ajay M.; Madhu, Basetti; Griffiths, John; Edwards, Lindsay M.; Mayr, Manuel

2013-01-01

298

Effects of perhexiline-induced fuel switch on the cardiac proteome and metabolome.  

PubMed

Perhexiline is a potent anti-anginal drug used for treatment of refractory angina and other forms of heart disease. It provides an oxygen sparing effect in the myocardium by creating a switch from fatty acid to glucose metabolism through partial inhibition of carnitine palmitoyltransferase 1 and 2. However, the precise molecular mechanisms underlying the cardioprotective effects elicited by perhexiline are not fully understood. The present study employed a combined proteomics, metabolomics and computational approach to characterise changes in murine hearts upon treatment with perhexiline. According to results based on difference in-gel electrophoresis, the most profound change in the cardiac proteome related to the activation of the pyruvate dehydrogenase complex. Metabolomic analysis by high-resolution nuclear magnetic resonance spectroscopy showed lower levels of total creatine and taurine in hearts of perhexiline-treated mice. Creatine and taurine levels were also significantly correlated in a cross-correlation analysis of all metabolites. Computational modelling suggested that far from inducing a simple shift from fatty acid to glucose oxidation, perhexiline may cause complex rebalancing of carbon and nucleotide phosphate fluxes, fuelled by increased lactate and amino acid uptake, to increase metabolic flexibility and to maintain cardiac output. This article is part of a Special Issue entitled "Focus on Cardiac Metabolism". PMID:23277191

Yin, Xiaoke; Dwyer, Joseph; Langley, Sarah R; Mayr, Ursula; Xing, Qiuru; Drozdov, Ignat; Nabeebaccus, Adam; Shah, Ajay M; Madhu, Basetti; Griffiths, John; Edwards, Lindsay M; Mayr, Manuel

2012-12-29

299

Role of breathing in cardiac performance: experimental and mathematical models  

NASA Astrophysics Data System (ADS)

Due to the close proximity of the heart and lungs within a closed chest environment, we expect breathing to affect various cardiac performance parameters and hence cardiac output. We present an integrative approach to study heart-lung interactions, combining a mathematical formulation of the circulation system with imaging techniques using echo-planar magnetic resonance imaging (EPI) and dynamic x-ray CT (EBCT). We hypothesize that appropriate synchronization of mechanical ventilation to cardiac-cycle specific events can improve cardiac function, i.e. stroke volume (SV) and cardiac output (CO). Computational and experimental results support the notion that heart-lung interaction, leading to altered cardiac output associated with inspiration/expiration, is not directly associated with lung inflation/deflation and thus is felt to be more influenced by pleural pressure changes. The mathematical model of the circulation demonstrates the importance of cardiac-cycle specific timing of ventilation on cardiac function and matches with experimentally observed relationships found in animal models studied via EBCT and human studies using EPI. Results show that positive pressure mechanical ventilation timed to systolic events may increase SV and CO by up to 30%, mainly by increased filling of the ventricles during diastole. Similarly, negative pressure (spontaneous) respiration has its greatest effect on ventricular diastolic filling. Cardiac-gated mechanical ventilation may provide sufficient cardiac augmentation to warrant further investigation as a minimally-invasive technique for temporary cardiac assist. Through computational modeling and advanced imaging protocols, we were able to uniquely study heart-lung interactions within the intact milieu of the never-invaded thorax.

Tran, Binh Q.; Hoffman, Eric A.

1999-05-01

300

Low-Output Left Ventricular Failure in End-Stage Renal Disease  

Microsoft Academic Search

To determine the factors associated with low-output left ventricular failure (LVF) in endstage renal disease (ESRD), we performed echocardiography and gated cardiac scan on 217 nondiabetic dialysis and transplant patients. The prevalence of low-output LVF (ejection fraction < 55% and left ventricular end diastolic diameter s⩾ 5.5 cm) in dialysis patients was 18% and in transplant patients 2%. The 26

Patrick S. Parfrey; John D. Harnett; Sheila Griffiths; Henry Gault; Paul E. Barre; Ronald D. Guttmann

1987-01-01

301

Age-associated changes in cardiac matrix and integrins  

Microsoft Academic Search

The progressive shift from young age to senescence is characterized by structural and functional changes in the cardiac extracellular matrix (ECM), which supports and aligns myocytes and blood vessels, and maintains myocardial mass, structure and function. As cardiac function declines with advancing age, ECM collagen and fibronectin influence diastolic stiffness. ECM binding to membrane-bound receptors, or integrins, directly links ECM

Maria Lonnett Burgess; Jennifer C. McCrea; Heather L. Hedrick

2001-01-01

302

Cardiac Cells Beating in Culture: A Laboratory Exercise  

ERIC Educational Resources Information Center

|This article describes how to establish a primary tissue culture, where cells are taken directly from an organ of a living animal. Cardiac cells are taken from chick embryos and transferred to culture dishes. These cells are not transformed and therefore have a limited life span. However, the unique characteristics of cardiac cells are maintained

Weaver, Debora

2007-01-01

303

NITROGEN OUTPUTS OF SMALL MAMMALS FROM FECAL AND URINE DEPOSITION: IMPLICATIONS FOR NITROGEN CYCLING  

EPA Science Inventory

The contribution of small mammals in nitrogen cycling is poorly understood and could have reverberations back to the producer community by maintaining or even magnifying increased nitrogen availability. Our objective was to model nitrogen outputs (deposition of feces and urine) ...

304

High output power widely tunable laser module  

NASA Astrophysics Data System (ADS)

We have developed highly reliable widely tunable module, whose performances were comparable with fixed-wavelength DFB laser module. To realize wide tunability, 12 l/4-shifted DFB laser array, S-bend waveguides, MMI coupler and an SOA were integrated on a chip. We could achieve 37nm tunability by controlling each chip temperature in the range of 5 to 45°C. High output fiber coupled power of 30mW and very uniform L-I curves out of 12 DFB lasers were achieved even at 50°C. Good quality of lasing spectrum was obtained. Side mode suppression ratio (SMSR) > 45dB. The well-suppressed reflection at chip front facet contributed to the lower noise characteristics, such as RIN < -140dB/Hz and linewidth < 4MHz. The shift of locked frequency was less than 0.4GHz as the case temperature varied from -5 to 75°C. Very small frequency shift was realized by controlling the temperature of locker part, independently. By optimizing TEC design, we could achieve low TEC power consumption less than 4W under Tcase=75°C and the end of life condition of SOA current. The new function by incorporating SOA was VOA. By changing the operating SOA current, we could vary output power from 1mW to 20mW, maintaining SMSR > 40dB, RIN < -135dB/Hz, linewidth < 4MHz. We also performed optical blocking > 40dB, when SOA current was turned off. We examined modules reliability under high temperature storage of 85°C. The change of output power was < +/- 10%, and the shift of locked frequency was < +/- 5pm after 2000 hours.

Mukaihara, Toshikazu; Kurobe, Tatsuro; Kimoto, Tatsuya; Shinagawa, Tatsuyuki; Nishita, Masayoshi; Kasukawa, Akihiko

2004-10-01

305

Quantifying PV power Output Variability  

SciTech Connect

This paper presents a novel approach to rigorously quantify power Output Variability from a fleet of photovoltaic (PV) systems, ranging from a single central station to a set of distributed PV systems. The approach demonstrates that the relative power Output Variability for a fleet of identical PV systems (same size, orientation, and spacing) can be quantified by identifying the number of PV systems and their Dispersion Factor. The Dispersion Factor is a new variable that captures the relationship between PV Fleet configuration, Cloud Transit Speed, and the Time Interval over which variability is evaluated. Results indicate that Relative Output Variability: (1) equals the inverse of the square root of the number of systems for fully dispersed PV systems; and (2) could be further minimized for optimally-spaced PV systems. (author)

Hoff, Thomas E. [Clean Power Research, Napa, CA (United States); Perez, Richard [ASRC, The University at Albany, Albany, NY (United States)

2010-10-15

306

Maintaining integrity on buried pipelines  

Microsoft Academic Search

This article outlines options available to the pipeline operator for monitoring the external corrosion protection systems applied to pipelines and describes the practices used by the British Pipeline Agency to maintain the integrity of some 2,500 km of pipelines. More than half of the network was constructed in the 1940s and water later replaced during the 1960s and 1970s with

1994-01-01

307

Indonesian drilling maintains steady pace  

SciTech Connect

Offshore drilling activity in Indonesia increased nominally the first quarter of 1985 to an average 29 rigs. Barring any further problems with oil prices and markets, operators are expected to maintain essentially the current general level of appraisal/development work for the rest of this year. There are still a number of prospective regions to be explored in Southeast Asia. Regional developments are described for the South China Sea area, the Java Sea, South Sumatra, Kalimantan, Irian Jaya and the Malacca Strait.

Not Available

1985-05-01

308

Cardiac aquaporins.  

PubMed

Aquaporins are a group of proteins with high-selective permeability for water. A subgroup called aquaglyceroporins is also permeable to glycerol, urea and a few other solutes. Aquaporin function has mainly been studied in the brain, kidney, glands and skeletal muscle, while the information about aquaporins in the heart is still scarce. The current review explores the recent advances in this field, bringing aquaporins into focus in the context of myocardial ischemia, reperfusion, and blood osmolarity disturbances. Since the amount of data on aquaporins in the heart is still limited, examples and comparisons from better-studied areas of aquaporin biology have been used. The human heart expresses aquaporin-1, -3, -4 and -7 at the protein level. The potential roles of aquaporins in the heart are discussed, and some general phenomena that the myocardial aquaporins share with aquaporins in other organs are elaborated. Cardiac aquaporin-1 is mostly distributed in the microvasculature. Its main role is transcellular water flux across the endothelial membranes. Aquaporin-4 is expressed in myocytes, both in cardiac and in skeletal muscle. In addition to water flux, its function is connected to the calcium signaling machinery. It may play a role in ischemia-reperfusion injury. Aquaglyceroporins, especially aquaporin-7, may serve as a novel pathway for nutrient delivery into the heart. They also mediate toxicity of various poisons. Aquaporins cannot influence permeability by gating, therefore, their function is regulated by changes of expression-on the levels of transcription, translation (by microRNAs), post-translational modification, membrane trafficking, ubiquitination and subsequent degradation. Studies using mice genetically deficient for aquaporins have shown rather modest changes in the heart. However, they might still prove to be attractive targets for therapy directed to reduce myocardial edema and injury caused by ischemia and reperfusion. PMID:24158693

Rutkovskiy, Arkady; Valen, Guro; Vaage, Jarle

2013-10-25

309

NMG documentation, part 3: maintainer`s guide  

SciTech Connect

This is the third of a three-part report documenting NMG, the Numerical Mathematics Guide. Part I is aimed at the user of the systenL It contains an introduction, with an out- line of the complete report, and Chapter 1, User`s Point of View. Part II is aimed at the programmer and contains Chapter 2, How It Works. Part III is aimed at the maintainer of NMG and contains Chapter 3, Maintenance, and Chapter 4, Validation. Because its contents are so specialized, Part III will receive only limited distribution. Note that each chapter has its own page numbering and table of contents.

Fritsch, F.N.; Dickinson, R.P. Jr.

1996-07-01

310

Technique for sensing inductor and DC output currents of PWM DC-DC converter  

Microsoft Academic Search

The design, analysis and trade-offs of a novel method to sense the inductor and DC output currents of PWM converters are presented. By sensing and adding appropriately the currents in the transistor, rectifier and capacitors of a converter using current transformers, the waveforms of inductor and DC output currents can be reconstructed accurately while maintaining isolation. This method offers high

Kwok-Wai Ma; Yim-Shu Lee

1994-01-01

311

Pseudo-pericardial tamponade after cardiac surgery.  

PubMed

Cardiac tamponade is a common cause of hypotension and low output after cardiac surgery. The authors present a case of false tamponade diagnosis on transesophageal echocardiography in a patient who underwent mitral valve replacement and coronary artery bypass grafting. The diagnosis was not confirmed at surgery, and the cause of the abnormal right atrial filling was a prominent Eustachian valve trapped in the suture for correction of an iatrogenic inferior vena cava laceration. Such a complication must be kept in mind when repairing inferior vena cava lacerations and should be more widely known. PMID:19117724

Almeida, Jorge; Garcia, Raquel; Monteiro, Vítor; Pinho, Paulo

2008-12-31

312

Output Interference in Recognition Memory  

ERIC Educational Resources Information Center

Dennis and Humphreys (2001) proposed that interference in recognition memory arises solely from the prior contexts of the test word: Interference does not arise from memory traces of other words (from events prior to the study list or on the study list, and regardless of similarity to the test item). We evaluate this model using output

Criss, Amy H.; Malmberg, Kenneth J.; Shiffrin, Richard M.

2011-01-01

313

Approximation theory of output statistics  

Microsoft Academic Search

Given a channel and an input process we study the minimum randomness of those input processes whose output statistics approximate the original out- put statistics with arbitrary accuracy. We introduce the notion of resolva- bility of a channel, defined as the number of random bits required per channel use in order to generate an input that achieves arbitrarily accu- rate

Te Sun Han; Sergio Verdii

1993-01-01

314

Output growth volatility and remittances  

Microsoft Academic Search

Since output growth volatility has negative effects on growth, poverty and welfare, especially in poorer countries, it is crucial to identify the country-specific factors that affect it. The empirical literature has focused mostly on financial development, policy distortions and globalization variables. Among the latter, attention has been directed in particular to trade and financial openness. We contribute to this literature

Matteo Bugamelli

2008-01-01

315

Online error correcting output codes  

Microsoft Academic Search

This article proposes a general extension of the error correcting output codes framework to the online learning scenario. As a result, the final classifier handles the addition of new classes independently of the base classifier used. In particular, this extension supports the use of both online example incremental and batch classifiers as base learners. The extension of the traditional problem

Sergio Escalera; David Masip; Eloi Puertas; Petia Radeva; Oriol Pujol

2011-01-01

316

Neuroadaptive output feedback control for automated anesthesia with noisy EEG measurements  

Microsoft Academic Search

Critical care patients, whether undergoing surgery or recovering in intensive care units, require drug administration to regulate physiological variables such as blood pressure, cardiac output, heart rate, and degree of consciousness. The rate of infusion of each administered drug is critical, requiring constant monitoring and frequent adjustments. Nonnegative and compartmental models provide a broad framework for biological and physiological systems,

Wassim M. Haddad; Konstantin Y. Volyanskyy; James M. Bailey

2008-01-01

317

Neuroadaptive Output Feedback Control for Automated Anesthesia With Noisy EEG Measurements  

Microsoft Academic Search

Critical care patients, whether undergoing surgery or recovering in intensive care units, require drug administration to regulate physiological variables such as blood pressure, cardiac output, heart rate, and degree of consciousness. The rate of infu- sion of each administered drug is critical, requiring constant moni- toring and frequent adjustments. Nonnegativeand compartmental modelsprovideabroadframeworkforbiologicalandphysiological systems, including clinical pharmacology, and are well suited

Wassim M. Haddad; Kostyantyn Y. Volyanskyy; James M. Bailey; Jeong Joon Im

2011-01-01

318

[Cardiac prosthesis].  

PubMed

It has been demonstrated an intrathoracic artificial heart with membrane pump delivering a pulsed flow and connected with an extracorporeal source of energy can keep a cardiotomized animal alive for several months without biological organic disturbances. The next experimental step would be intrathoracic implantation in man of a similar heart with an energy converter connected to an extracorporeal source giving the patient a 6-8 hour period of autonomy. At rest or during the night the batteries attached to the patient's waist would easily be recharged. Current research concentrates on reduction of artificial heart volume and miniaturization of the energy converter and regulatory electronic circuits. Kinetic pumps, which are small and without valvular prosthesis facilitate miniaturization. They deliver a high-speed continuous flow and have not yet been shown in long-term experiments to be free from biological disturbances. The clinical phase of stage II artificial hearts, due to begin in 1990, will be preceded by attempts at implanting hearts animated by an extracorporeal source of energy, pending cardiac replacement. PMID:6219372

Marion, P

1983-02-26

319

10 CFR 26.71 - Maintaining authorization.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Maintaining authorization. 26.71 Section 26.71 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Granting and Maintaining Authorization § 26.71 Maintaining authorization. (a)...

2013-01-01

320

Origin of Cardiac Fibroblasts and the Role of Periostin  

PubMed Central

Cardiac fibroblasts are the most populous non-myocyte cell type within the mature heart and are required for extracellular matrix synthesis and deposition, generation of the cardiac skeleton, and to electrically insulate the atria from the ventricles. Significantly, cardiac fibroblasts have also been shown to play an important role in cardiomyocyte growth and expansion of the ventricular chambers during heart development. Although there are currently no cardiac fibroblast-restricted molecular markers, it is generally envisaged that the majority of the cardiac fibroblasts are derived from the proepicardium via epithelial-to-mesenchymal transformation. However, still relatively little is known about when and where the cardiac fibroblasts cells are generated, the lineage of each cell, and how cardiac fibroblasts move to reside in their final position throughout all four cardiac chambers. In this review we summarize the current understanding regarding the function of Periostin, a useful marker of the non-cardiomyocyte lineages, and its role during cardiac morphogenesis. Characterization of the cardiac fibroblast lineage and identification of the signals that maintain, expand and regulate their differentiation will be required to improve our understanding of cardiac function in both normal and pathophysiological states.

Snider, Paige; Standley, Kara N.; Wang, Jian; Azhar, Mohamad; Doetschman, Thomas; Conway, Simon J.

2009-01-01

321

Gymnasium-based unsupervised exercise maintains benefits in oxygen uptake kinetics obtained following supervised training in type 2 diabetes.  

PubMed

Supervised exercise (SE) in patients with type 2 diabetes improves oxygen uptake kinetics at the onset of exercise. Maintenance of these improvements, however, has not been examined when supervision is removed. We explored if potential improvements in oxygen uptake kinetics following a 12-week SE that combined aerobic and resistance training were maintained after a subsequent 12-week unsupervised exercise (UE). The involvement of cardiac output (CO) in these improvements was also tested. Nineteen volunteers with type 2 diabetes were recruited. Oxygen uptake kinetics and CO (inert gas rebreathing) responses to constant-load cycling at 50% ventilatory threshold (V(T)), 80% V(T), and mid-point between V(T) and peak workload (50% ?) were examined at baseline (on 2 occasions) and following each 12-week training period. Participants decided to exercise at a local gymnasium during the UE. Thirteen subjects completed all the interventions. The time constant of phase 2 of oxygen uptake was significantly faster (p < 0.05) post-SE and post-UE compared with baseline at 50% V(T) (17.3 ± 10.7 s and 17.5 ± 5.9 s vs. 29.9 ± 10.7 s), 80% V(T) (18.9 ± 4.7 and 20.9 ± 8.4 vs. 34.3 ± 12.7s), and 50% ? (20.4 ± 8.2 s and 20.2 ± 6.0 s vs. 27.6 ± 3.7 s). SE also induced faster heart rate kinetics at all 3 intensities and a larger increase in CO at 30 s in relation to 240 s at 80% V(T); and these responses were maintained post-UE. Unsupervised exercise maintained benefits in oxygen uptake kinetics obtained during a supervised exercise in subjects with diabetes, and these benefits were associated with a faster dynamic response of heart rate after training. PMID:22563745

Macananey, Oscar; O'Shea, Donal; Warmington, Stuart A; Green, Simon; Egaña, Mikel

2012-05-07

322

Model-based interpretation of cardiac beats by evolutionary algorithms  

Microsoft Academic Search

This work presents current progress of a new system for cardiac beat interpretation, combining model-based reasoning and evolutionary computing. As a difference from other model-based systems, the proposed approach directly integrates ECG signals with a cardiac model. Model-based reasoning is formalized as the minimization of an error function defined between the observation and the model's output. This paper presents a

A. Hemdndez; G. Carrault; F. Mora

2002-01-01

323

When to maintain centrifugal pumps  

SciTech Connect

Centrifugal pumps comprise critical maintenance equipment. The rationale of when to maintain them relates to a spreading tendency to contain costs in the face of tight money. Plant managers are thus entitled to a thorough analysis of whether reduced expenditures truly lower costs or actually hinder maintenance and increase costs. Absence of such an analysis hides the fact that proper and timely maintenance has a double effect: it not only reduces power consumption but also extends equipment life, and thus reduces the frequency of labor and material expenditures for scheduled or crisis maintenance. Centrifugal pump maintenance can demonstrate well the validity of this observation. The paper discusses: restoring internal clearances; real cost of renewing clearances; and monitoring clearances and pump performance.

Karassik, I.J.

1993-04-01

324

Explicit feedback maintains implicit knowledge.  

PubMed

The role of feedback was investigated with respect to conscious and unconscious knowledge acquired during artificial grammar learning (AGL). After incidental learning of training sequences, participants classified further sequences in terms of grammaticality and reported their decision strategy with or without explicit veridical feedback. Sequences that disobeyed the learning structure conformed to an alternative structure. Feedback led to an increase in the amount of reported conscious knowledge of structure (derived rules and recollections) but did not increase its accuracy. Conversely, feedback maintained the accuracy of unconscious knowledge of structure (intuition or familiarity-based responses) which otherwise degraded. Results support a dual-process account of AGL. They suggest that implicit learning of the to-be-rejected structure at test contaminates familiarity-based classifications whereas feedback allows competing familiarity signals to be contextualised, which is incompatible with theories that consider familiarity context-insensitive. PMID:23770696

Mealor, Andy D; Dienes, Zoltan

2013-06-13

325

COOPERATION MAINTAINED BY FITNESS ADJUSTMENT  

PubMed Central

Questions Whether or not cooperation can be enhanced if players with a performance higher than the mean are forced to pay an additional cost in each generation? Mathematical Methods Analysis of replicator dynamics with mutation. The ESS distribution of cooperation level is obtained. Key Assumptions Players engage in cooperative dilemma game, and at the end of each generation, those with higher performance than the mean are forced to pay additional cost. Conclusions Without mutation, the entire population eventually conforms to a single cooperation level determined by the initial composition of the population. With mutation, there is an equilibrium distribution of cooperation level, which has a peak at an intermediate level of cooperation. Whether it is institutionalized such as tax or just a social custom, fitness adjustment based ultimately on people’s emtion of “envy” is able to maintain cooperation.

TAYLOR, CHRISTINE; CHEN, JANET; IWASA, YOH

2008-01-01

326

Thymic output, ageing and zinc  

Microsoft Academic Search

The role of the thymus is vital for orchestration of T-cell development and maturation. With increasing age the thymus undergoes a process of involution which results in a reduction in thymic size, function and output. Until relatively recent it was not feasible to accurately measure the magnitude of age-related loss of thymic function. With the discovery of T-cell receptor excision

Wayne A Mitchell; Irene Meng; Stuart A Nicholson; Richard Aspinall

2006-01-01

327

Myo-cortical crossed feedback reorganizes primate motor cortex output  

PubMed Central

The motor system is capable of adapting to changed conditions such as amputations or lesions by reorganizing cortical representations of peripheral musculature. To investigate the underlying mechanisms we induced targeted reorganization of motor output effects by establishing an artificial recurrent connection between a forelimb muscle and an unrelated site in primary motor cortex (M1) of macaques. A head-fixed computer transformed forelimb electromyographic (EMG) activity into proportional subthreshold intracortical microstimulation during hours of unrestrained volitional behavior. This conditioning paradigm stimulated the cortical site for a particular muscle in proportion to activation of another muscle and induced robust site- and input-specific reorganization of M1 output effects. Reorganization was observed within 25 minutes and could be maintained with intermittent conditioning for successive days. Control stimulation that was independent of muscle activity, termed ‘pseudoconditioning,’ failed to produce reorganization. Pre-conditioning output effects were gradually restored during volitional behaviors following the end of conditioning. The ease of changing the relationship between cortical sites and associated muscle responses suggests that under normal conditions these relations are maintained through physiological feedback loops. These findings demonstrate that motor cortex outputs may be reorganized in a targeted and sustainable manner through artificial afferent feedback triggered from controllable and readily recorded muscle activity. Such cortical reorganization has implications for therapeutic treatment of neurological injuries.

Lucas, Timothy H.; Fetz, Eberhard E.

2013-01-01

328

Cold-impaired cardiac performance in rats is only partially overcome by cold acclimation.  

PubMed

The consequences of acute hypothermia include impaired cardiovascular performance, ultimately leading to circulatory collapse. We examined the extent to which this results from intrinsic limitations to cardiac performance or physiological dysregulation/autonomic imbalance, and whether chronic cold exposure could ameliorate the impaired function. Wistar rats were held at a 12 h:12 h light:dark (L:D) photoperiod and room temperature (21°C; euthermic controls), or exposed to a simulated onset of winter in an environmental chamber by progressive acclimation to 1 h:23 h L:D and 4°C over 4 weeks. In vivo, acute cold exposure (core temperature, T(b)=25°C) resulted in hypotension (approximately -20%) due to low cardiac output (approximately -30%) accompanying a bradycardia (approximately -50%). Cold acclimation (CA) induced only partial compensation for this challenge, including increased coronary flow at T(b)=37°C (but not at T(b)=25°C), maintenance of ventricular capillarity and altered sympathovagal balance (increased low:high frequency in power spectral analysis, PSA), suggesting physiological responses alone were insufficient to maintain cardiovascular performance. However, PSA showed maintenance of cardiorespiratory coupling on acute cold exposure in both groups. Ex vivo cardiac performance revealed no change in intrinsic heart rate, but a mechanical impairment of cardiac function at low temperatures following CA. While CA involved an increased capacity for ?-oxidation, there was a paradoxical reduction in developed pressure as a result of adrenergic down-regulation. These data suggest that integrated plasticity is the key to cardiovascular accommodation of chronic exposure to a cold environment, but with the potential for improvement by intervention, for example with agents such as non-catecholamine inotropes. PMID:21865514

Hauton, David; May, Shaun; Sabharwal, Rasna; Deveci, Durmus; Egginton, Stuart

2011-09-15

329

Cardiac beat frequency and oxygen supply: a comparative study.  

PubMed

The length of diastole in mammals varies between approx 1 s (elephant) and 38 ms (shrew) which makes oxygen supply in high speed cardiac pumps in very small mammals precarious. High capillary density and high blood P50 are reported in mammals with high frequency cardiac cycle. Both are probably insufficient when cardiac frequency is exceedingly high (shrew: 1000 min-1). High respiratory efficiency due to large relative mitochondrial volume per cell (greater than 50%) seems to be preferential solution to maintain sufficient O2-gradient. Similar strategy, i.e. high relative cardiac mitochondrial volume was reported in analogous situation in ice-fish (Chaenocephalus aceratus) where O2 cardiac cell supply is difficult due to the absence of hemoglobin and cardiac myoglobin. PMID:6146429

Poupa, O; Brix, O

1984-01-01

330

Caste ratios affect the reproductive output of social trematode colonies.  

PubMed

Intraspecific phenotypic diversification in social organisms often leads to formation of physical castes which are morphologically specialized for particular tasks within the colony. The optimal caste allocation theory argues that specialized morphological castes are efficient at specific tasks, and hence different caste ratios should affect the ergonomic efficiency, hence reproductive output of the colony. However, the reproductive output of different caste ratios has been documented in few species of insects with equivocal support for the theory. This study investigated whether the ratios of nonreproductive and reproductive morphs affect the reproductive output of a recently discovered social trematode, Philophthalmus sp., in which the nonreproductive members are hypothesized to be defensive specialists. A census of natural infections and a manipulative in vitro experiment demonstrated a positive association between the reproductive output of trematode colonies and the ratio of nonreproductive to reproductive morphs in the presence of an intra-host trematode competitor, Maritrema novaezealandensis. On the contrary, without the competitor, reproductive output was negatively associated with the proportion of nonreproductive castes in colonies. Our findings demonstrate for the first time a clear fitness benefit associated with the nonreproductive castes in the presence of a competitor while illustrating the cost of maintaining such morphs in noncompetitive situations. Although the proximate mechanisms controlling caste ratio remain unclear in this trematode system, this study supports the prediction that the fitness of colonies is influenced by the composition of specialized functional morphs in social organisms, suggesting a potential for adaptive shifts of caste ratios over evolutionary time. PMID:23252707

Kamiya, T; Poulin, R

2012-12-17

331

Retrotransposons that maintain chromosome ends  

PubMed Central

Reverse transcriptases have shaped genomes in many ways. A remarkable example of this shaping is found on telomeres of the genus Drosophila, where retrotransposons have a vital role in chromosome structure. Drosophila lacks telomerase; instead, three telomere-specific retrotransposons maintain chromosome ends. Repeated transpositions to chromosome ends produce long head to tail arrays of these elements. In both form and function, these arrays are analogous to the arrays of repeats added by telomerase to chromosomes in other organisms. Distantly related Drosophila exhibit this variant mechanism of telomere maintenance, which was established before the separation of extant Drosophila species. Nevertheless, the telomere-specific elements still have the hallmarks that characterize non-long terminal repeat (non-LTR) retrotransposons; they have also acquired characteristics associated with their roles at telomeres. These telomeric retrotransposons have shaped the Drosophila genome, but they have also been shaped by the genome. Here, we discuss ways in which these three telomere-specific retrotransposons have been modified for their roles in Drosophila chromosomes.

Pardue, Mary-Lou; DeBaryshe, P. G.

2011-01-01

332

Remotely maintained waste transfer pump  

SciTech Connect

Westinghouse Savannah River Company (WSRC) operates the Savannah River Site (SRS) for the Department of Energy (DOE). Waste from the processing of irradiated material is stored in large shielded tanks. Treated liquid wastes are to be transferred from these tanks to the Defense Waste Processing Facility (DWPF) for incorporation in glass suitable for storage in a federal repository. Characteristics of the wastes range from water-like liquid to highly viscous wastes containing suspended solids. Pumping head requirements for various conditions ranged from 10 meters (35 feet) to 168 meters (550 feet). A specially designed, cantilever type, remotely operated and maintained pump was designed and built to transfer the wastes. To demonstrate the design, a prototype pump was built and testing thoroughly with simulated waste. Severe vibration problems were overcome by proper drive shaft selection and careful control of the space between the pump shaft and fixed running clearances (sometimes called seals). Eleven pumps are now installed and six pumps have been successfully run in water service.

Eargle, J.C.

1990-12-31

333

Remotely maintained waste transfer pump  

SciTech Connect

Westinghouse Savannah River Company (WSRC) operates the Savannah River Site (SRS) for the Department of Energy (DOE). Waste from the processing of irradiated material is stored in large shielded tanks. Treated liquid wastes are to be transferred from these tanks to the Defense Waste Processing Facility (DWPF) for incorporation in glass suitable for storage in a federal repository. Characteristics of the wastes range from water-like liquid to highly viscous wastes containing suspended solids. Pumping head requirements for various conditions ranged from 10 meters (35 feet) to 168 meters (550 feet). A specially designed, cantilever type, remotely operated and maintained pump was designed and built to transfer the wastes. To demonstrate the design, a prototype pump was built and testing thoroughly with simulated waste. Severe vibration problems were overcome by proper drive shaft selection and careful control of the space between the pump shaft and fixed running clearances (sometimes called seals). Eleven pumps are now installed and six pumps have been successfully run in water service.

Eargle, J.C.

1990-01-01

334

Sudden Cardiac Arrest  

MedlinePLUS

... sudden, unexpected loss of heart function, breathing and consciousness. Sudden cardiac arrest usually results from an electrical ... Sudden collapse No pulse No breathing Loss of consciousness Sometimes other signs and symptoms precede sudden cardiac ...

335

Cardiac Arrhythmia Port.  

National Technical Information Service (NTIS)

The overall goal of the Cardiac Arrhythmia PORT was to identify the best strategies to prevent sudden cardiac death among patients with known heart disease. The authors documented substantial increases over time in specialized testing and use of implantab...

M. A. Hlaky

2000-01-01

336

Cardiac MRI in Athletes  

Microsoft Academic Search

Cardiac magnetic resonance imaging (CMR) is often used in athletes to image cardiac anatomy and function and is increasingly requested in the context of screening for pathology that can cause sudden cardiac death (SCD). In this thesis, patterns of cardiac adaptation to sports are investigated with CMR.\\u000a\\u000aChapter 2 describes our finding that left-right ratios are preserved across all sports

T. Luijkx

2012-01-01

337

Pediatric cardiac disorders  

Microsoft Academic Search

Although pediatric cardiac disorders are not commonly seen in the Emergency Department, they are important to identify to prevent further morbidity or mortality. Diagnosis may be complicated by the lack of classic complaints such as chest pain or palpitations that are commonly associated with cardiac disorders. In fact, presenting complaints associated with pediatric cardiac disorders, like “fussiness” or “difficulty feeding,”

Ghazala Q Sharieff; Todd W Wylie

2004-01-01

338

Cardiac tumours in children  

Microsoft Academic Search

Cardiac tumours are benign or malignant neoplasms arising primarily in the inner lining, muscle layer, or the surrounding pericardium of the heart. They can be primary or metastatic. Primary cardiac tumours are rare in paediatric practice with a prevalence of 0.0017 to 0.28 in autopsy series. In contrast, the incidence of cardiac tumours during foetal life has been reported to

Orhan Uzun; Dirk G Wilson; Gordon M Vujanic; Jonathan M Parsons; Joseph V De Giovanni

2007-01-01

339

Principles of cardiac anaesthesia  

Microsoft Academic Search

This article describes the anaesthetic management of patients undergoing cardiac surgery. The techniques used are principally those applied to patients with ischaemic heart disease, which represents 56% of all cardiac surgery carried out in the UK. Where appropriate, management strategies for those patients with aortic and mitral valve disease are discussed. Monitoring techniques used for cardiac anaesthesia are detailed along

John W. W. Gothard; James W. Keogh

2009-01-01

340

Cardiac Effects of Persistent Hemodialysis Arteriovenous Access in Recipients of Renal Allograft  

Microsoft Academic Search

In hemodialysis patients, large arteriovenous (AV) fistulas for vascular access may cause ventricular hypertrophy and high-output cardiac failure. The long-term cardiac consequences of functional AV fistulas in renal transplant patients are unclear. A precise knowledge of these consequences is important to decide if and when such fistulas should be closed in successfully transplanted patients. In this retrospective study including 61

José Jayme G. De Lima; Marcelo Luis Campos Vieira; Laszlo J. Molnar; Caio Jorge Medeiros; Luís Estevan Ianhez; Eduardo M. Krieger

1999-01-01

341

Impaired cardiac function in chronic fatigue syndrome measured using magnetic resonance cardiac tagging  

PubMed Central

Objectives Impaired cardiac function has been confirmed in patients with chronic fatigue syndrome (CFS). Magnetic resonance cardiac tagging is a novel technique that assesses myocardial wall function in vivo. We hypothesized that patients with CFS may have impaired development and release of myocardial torsion and strain. Methods Cardiac morphology and function were assessed using magnetic resonance imaging and cardiac tagging methodology in 12 CFS patients (Fukuda) and 10 matched controls. Results Compared to controls, the CFS group had substantially reduced left ventricular mass (reduced by 23%), end-diastolic volume (30%), stroke volume (29%) and cardiac output (25%). Residual torsion at 150% of the end-systolic time was found to be significantly higher in the patients with CFS (5.3 ± 1.6°) compared to the control group (1.7 ± 0.7°, P = 0.0001). End-diastolic volume index correlated negatively with both torsion-to-endocardial-strain ratio (TSR) (r = ?0.65, P = 0.02) and the residual torsion at 150% end-systolic time (r = ?0.76, P = 0.004), so decreased end-diastolic volume is associated with raised TSR and torsion persisting longer into diastole. Reduced end-diastolic volume index also correlated significantly with increased radial thickening (r = ?0.65, P = 0.03) and impaired diastolic function represented by the ratio of early to late ventricular filling velocity (E/A ratio, r = 0.71, P = 0.009) and early filling percentage (r = 0.73, P = 0.008). Conclusion Patients with CFS have markedly reduced cardiac mass and blood pool volumes, particularly end-diastolic volume: this results in significant impairments in stroke volume and cardiac output compared to controls. The CFS group appeared to have a delay in the release of torsion.

Hollingsworth, K G; Hodgson, T; MacGowan, G A; Blamire, A M; Newton, J L

2012-01-01

342

The cyclooxygenase-2 product prostaglandin E 2 modulates cardiac contractile function in adult rat ventricular cardiomyocytes  

Microsoft Academic Search

Prostaglandin E2 (PGE2), a product of the cyclooxygenase-2 pathway, has been shown to increase cardiac output and modulate cardiac contractile function. However, whether the cardiac contractile response of PGE2 is due to its action on single ventricular myocytes has not been elucidated. To assess the mechanical effect of PGE2 at the cellular level, adult rat ventricular myocytes were isolated and

Aaron L. Klein; Loren E. Wold; Jun Ren

2004-01-01

343

Opening the pericardium during pulmonary artery constriction improves cardiac function.  

PubMed

During acute pulmonary hypertension, both the pericardium and the right ventricle (RV) constrain left ventricular (LV) filling; therefore, pericardiotomy should improve LV function. LV, RV, and pericardial pressures and RV and LV dimensions and LV stroke volume (SV) were measured in six anesthetized dogs. The pericardium was closed, the chest was left open, and the lungs were held away from the heart. Data were collected at baseline, during pulmonary artery constriction (PAC), and after pericardiotomy with PAC maintained. PAC decreased SV by one-half. RV diameter increased, and septum-to-LV free wall diameter and LV area (our index of LV end-diastolic volume) decreased. Compared with during PAC, pericardiotomy increased LV area and SV increased 35%. LV and RV compliance (pressure-dimension relations) and LV contractility (stroke work-LV area relations) were unchanged. Although series interaction accounts for much of the decreased cardiac output during acute pulmonary hypertension, pericardial constraint and leftward septal shift are also important. Pericardiotomy can improve LV function in the absence of other sources of external constraint to LV filling. PMID:14578366

Belenkie, Israel; Sas, Rozsa; Mitchell, Jamie; Smith, Eldon R; Tyberg, John V

2003-10-24

344

Training, competency, and certification in cardiac CT: A summary statement from the Society of Cardiovascular Computed Tomography  

Microsoft Academic Search

Training and competency criteria in cardiac CT were developed to guide practitioners in the process of achieving and maintaining skills in performing and interpreting cardiac CT studies. Appropriate training and eventual certification in cardiac CT angiography may be obtained by adhering to the recommendations for competency as set forth by either the American College of Cardiology Foundation (ACCF) or the

Robert Pelberg; Matthew Budoff; Tauqir Goraya; Jon Keevil; John Lesser; Sheldon Litwin; Carter Newton; Michael Ridner; John Rumberger; Shawn Teague; Michael Winkler

2011-01-01

345

Emergency cardiac support with extracorporeal membrane oxygenation for cardiac arrest.  

PubMed

A 46-year-old woman with no major medical history presented to the emergency department with chest pain and evidence of anterior, anterolateral, and inferior ST-elevation myocardial infarction. Her condition quickly deteriorated into cardiogenic shock with ventricular arrhythmia. Despite revascularization of the left anterior descending artery and intravenous inotrope and antiarrhythmic therapy, her unstable hemodynamics and arrhythmias persisted. Early emergency initiation of venoarterial extracorporeal membrane oxygenation (ECMO) led to prompt hemodynamic and rhythm stability; however, adequate endogenous cardiac output did not ensue, and she was not able to be weaned from ECMO until hospital day 8. She subsequently recovered and continues to do well in the outpatient setting. This case demonstrates the remarkable hemodynamic and rhythm stability that early initiation of ECMO can provide in the setting of unstable myocardial infarction. PMID:23809321

Tweet, Marysia S; Schears, Gregory J; Cassar, Andrew; Sheldon, Seth H; McGlinch, Brian P; Sandhu, Gurpreet S

2013-07-01

346

Output error identification without SPR assumptions  

Microsoft Academic Search

This paper uses an input-output stability analysis approach to show that for a large class of output error identification algorithms, the usual strict positive real (SPR) conditions on the unknown plant can be replaced by \\

Dale A. Lawrence; C. Richard Johnson

1984-01-01

347

CYCLOPS Objective Steering Model Output Statistics (COSMOS).  

National Technical Information Service (NTIS)

COSMOS is a statistical aid designed to assist the forecastor in interpreting CYCLOPS output. Using CYCLOPS (a geostrophic steering model) output in the unmodified prognostic mode for the 850, 700, and 500 mb levels, the model categorizes the forecast sit...

R. L. Allen

1984-01-01

348

THE CARDIOVASCULAR RESPONSES OF THE RED-EARED SLIDER (TRACHEMYS SCRIPTA) ACCLIMATED TO EITHER 22 OR 5 °C I. EFFECTS OF ANOXIC EXPOSURE ON IN VIVO CARDIAC PERFORMANCE  

Microsoft Academic Search

The extreme anoxia-tolerance of freshwater turtles under cold conditions is well documented, but little is known about their cardiac performance in such situations. Using chronic catheterization techniques, we measured systemic cardiac power output (POsys), systemic cardiac output (Q. sys), heart rate (fH), systemic stroke volume (Vs,sys), systemic resistance (Rsys) and mean arterial pressure (Psys) in red-eared sliders (Trachemys scripta). The

J. M. T. HICKS; A. P. FARRELL

349

Double Integrator Magnetic Amplifier Output Circuit.  

National Technical Information Service (NTIS)

The magnetic amplifier has an integrating circuit adapted to produce a sinusoidal output voltage. Two properly rated integrating circuits are applied to the output of a push-pull magnetic amplifier. An output current may be provided flowing through the ex...

W. A. Geyher

1965-01-01

350

Characterization of a flow-through microcalorimeter for measuring the heat production of cardiac trabeculae  

NASA Astrophysics Data System (ADS)

The energy consumption of isolated cardiac trabeculae can be inferred from measurements of their heat production. Once excised from the heart, to remain viable, trabeculae require continuous superfusion with an oxygen- and nutrient-rich solution. Flow-through calorimeters enable trabeculae to be maintained in a stable and controlled environment for many hours at a time. In this paper we describe and characterize a flow-through microcalorimeter, with sensitivity in the 1 ?W range, for measuring the heat output of 10 ?g cardiac trabeculae. The device uses infrared-sensitive, thin-film thermopile sensors to provide a noncontact method for measuring temperature differences. The sensors are capable of resolving 5 ?K temperature differences within the superfusing fluid. The microcalorimeter has a sensitivity of 2.56 V/W at a flow rate of 1 ?l/s, with a time constant of approximately 3.5 s. The sensitivity and time constant are strongly dependent upon the flow rate. Predictions of a finite-element model of the calorimeter's characteristics compare favorably with measured data over a wide range of flow rates.

Taberner, A. J.; Hunter, I. W.; Kirton, R. S.; Nielsen, P. M. F.; Loiselle, D. S.

2005-10-01

351

[Intravenous isosorbide dinitrate in acute cardiac failure (author's transl)].  

PubMed

Isosorbide dinitrate (ISDN) was used by intravenous infusion in 7 patients with acute cardiac failure consecutive to acute (5) or chronic (1) myocardial infarction or to non-obstructive cardiomyopathy (1). Pulmonary artery pressure (PAP), pulmonary capillary pressure (PCP), right atrial pressure (RAP) and cardiac output were measured (PCP), right atrial pressure (RAP) and cardiac output were measured by intracardiac catheterization. The initial dosage of 2.5 mg/hour was increased until PCP was reduced to 15 mmHg or less or until troublesome side-effects developed. Control was achieved in 3 patients with doses of 2.5 to 7 mg/hour and, to a lesser extent, in one patient with up to 20 mg/hour. Three patients failed to respond even to higher doses and needed furosemide i.v. or furosemide + dobutamine. One patient died of cardiogenic shock. No changes in cardiac output, heart rate and blood pressure and no clinical side-effects were recorded. Thus, in acute cardiac failure ISDN may be effective in doses slightly superior to those of nitroglycerin, but increasing the dosage above 7 or 8 mg/hour does not bring additional benefits. The drug is remarkably well tolerated. PMID:7110970

Lamaison, D; Lusson, J R; Cassagnes, J; Teyssonneyre, B; Bailey, P; Jallut, H

1982-06-10

352

Space Maintainers for Premature Tooth Loss  

MedlinePLUS

... To make a removable space maintainer, the dentist first makes impressions. They are sent to a lab, which makes the appliance. Caring for Your Space Maintainer The space maintainer may feel unusual at first. But after a few days, your child probably ...

353

Development of maintainability index for mechanical systems  

Microsoft Academic Search

A procedure based on a digraph and matrix method is developed for evaluation of maintainability index of mechanical systems. Features which characterize or ease in maintenance of a system are identified and are called the maintainability attributes. Consideration of these attributes and their interrelations are rudiment in evaluating the index. This is modeled in terms of a Maintainability Attributes Digraph

M. F. Wani; O. P. Gandhi

1999-01-01

354

Respiratory and cardiac effects of passive limb movements in man  

Microsoft Academic Search

The purpose of these experiments is to see if reflex nervous hyperventilation obtained by passive limb movements in man is a consequence of the activation of a direct ascending nervous pathway from mechanoreceptors of moving limbs to respiratory centres, or if it is the consequence of a primary enhanced cardiodynamic activity. Contemporaneous measurements of pulmonary ventilation and cardiac output (the

Alberto Concu; Fisiologia Umana

1988-01-01

355

4D iterative reconstruction in cardiac CT  

NASA Astrophysics Data System (ADS)

In this paper, a 4D iterative reconstruction scheme is developed to improve noise characteristics and/or reduce radiation exposure in multi-slice cardiac CT. In our implementation, image volume datasets are reconstructed at adjacent temporal positions with respect to an optimized cardiac phase (best phase). Nonlinear regularization priors operate on a 4D cube surrounding each voxel in 4D space, reducing image noise while maintaining temporal and spatial image sharpness. The temporal resolution of image data is maintained despite the usage of temporal data that can substantially exceed the reconstruction range of the 'best phase' reconstruction. Consequently, the noise statistics is significantly improved because non-correlated image data at different temporal positions are utilized. To reduce the high computational load, the iterative regularization in 4D can be transferred into image space. Raw data based Iterative Reconstruction reducing artifacts due to the non-exactness of the backprojector is decoupled from regularization and restricted to only those projection data belonging to the 'best phase' reconstruction. Finally, the image formation is achieved by a normalized combination of the low frequency part of the raw data based Iterative Reconstruction at cardiac best phase and the high frequency part of the image based regularization image at best phase. We demonstrate the potential of noise reduction on basis of clinical cardiac CT data. As an example for cardiac dual source CT (DSCT) data a noise reduction up to 70% was achieved. Even in case of a very high and irregular heart beat with an average heart rate of 115 bpm the high temporal resolution of DSCT could be maintained.

Bruder, H.; Raupach, R.; Allmendinger, T.; Sunnegårdh, J.; Stierstorfer, K.; Flohr, T.

2012-02-01

356

TNNI3K, a Cardiac-Specific Kinase, Promotes Physiological Cardiac Hypertrophy in Transgenic Mice  

PubMed Central

Purpose Protein kinase plays an essential role in controlling cardiac growth and hypertrophic remodeling. The cardiac troponin I-interacting kinase (TNNI3K), a novel cardiac specific kinase, is associated with cardiomyocyte hypertrophy. However, the precise function of TNNI3K in regulating cardiac remodeling has remained controversial. Methods and Results In a rat model of cardiac hypertrophy generated by transverse aortic constriction, myocardial TNNI3K expression was significantly increased by 1.62 folds (P<0.05) after constriction for 15 days. To investigate the role of TNNI3K in cardiac hypertrophy, we generated transgenic mouse lines with overexpression of human TNNI3K specifically in the heart. At the age of 3 months, the high-copy-number TNNI3K transgenic mice demonstrated a phenotype of concentric hypertrophy with increased heart weight normalized to body weight (1.31 fold, P<0.01). Echocardiography and non-invasive hemodynamic assessments showed enhanced cardiac function. No necrosis or myocyte disarray was observed in the heart of TNNI3K transgenic mice. This concentric hypertrophy maintained up to 12 months of age without cardiac dysfunction. The phospho amino acid analysis revealed that TNNI3K is a protein-tyrosine kinase. The yeast two-hybrid screen and co-immunoprecipitation assay identified cTnI as a target for TNNI3K. Moreover, TNNI3K overexpression induced cTnI phosphorylation at Ser22/Ser23 in vivo and in vitro, suggesting that TNNI3K is a novel upstream regulator for cTnI phosphorylation. Conclusion TNNI3K promotes a concentric hypertrophy with enhancement of cardiac function via regulating the phosphorylation of cTnI. TNNI3K could be a potential therapeutic target for preventing from heart failure.

Su, Ming; Wang, Changxin; Chen, Jingzhou; Wang, Hu; Song, Lei; Zou, Yubao; Zhang, Lianfeng; Zhang, Youyi; Hui, Rutai

2013-01-01

357

Cardiac dysfunction during status epilepticus in the neonatal pig.  

PubMed

Cardiovascular complications frequently occur during status epilepticus. To determine the changes in systemic and pulmonary arterial pressure, cardi output, and left ventricular contractility during seizures, 1-week-old pigs were intubated, paralyzed, mechanicall entilated, and catheterized with a Swan-Ganz catheter. Seizures were induced with intravenous bicuculline. Early changes consisted of significant systemic and pulmonary arterial hypertension. After 2 hours of seizures, the animals developed progressive systemic hypotension and decreased cardiac output. M-mode echocardiography disclosed a decrease in left ventricular contractility. Cardiac tissue frozen in situ showed a significant increase in lactate and reductions in glucose, triglyceride, and adenosine triphosphate levels. Prolonged seizures in the neonatal pig result in cardiac dysfunction, which may play a role in the development of epileptic brain damage. PMID:4051458

Young, R S; Fripp, R R; Yagel, S K; Werner, J C; McGrath, G; Schuler, H G

1985-09-01

358

Compromised cardiac function in exercising teenagers with pectus excavatum.  

PubMed

Patients with pectus excavatum complain about fatigue, tachypnea, discomfort and dyspnea, but the existence of an equivalent underlying pathophysiology has been questioned. We investigated 75 teenagers (49 pectus excavatum patients and 26 age matched controls) at rest and during bicycle exercise at submaximal exercise levels. At rest cardiac function was determined using echocardiography. During rest and exercise, cardiac output, heart rate and aerobic exercise capacity were measured using photo-acoustic gas-rebreathing technique for non-invasive determination of the cardiopulmonary function. At rest, no cardiac differences were found between control subjects and patients with pectus excavatum. During submaximal exercise, cardiac index was lower 6.6(6.3-7.0) l/min/m(2) among the pectus patients as compared to the control subjects 8.0(7.3-8.8) l/min/m(2), P=0.0001. The lower cardiac output among the pectus patients was due to a lower stroke index 42(39-45) ml/beat/m(2) as compared to controls 54(44-64) ml/beat/m(2), P=0.0022, whereas heart rate was unchanged. Cardiac function is significantly impaired at submaximal exercise level compared to healthy age matched controls. PMID:21788301

Lesbo, Maj; Tang, Mariann; Nielsen, Hans Henrik; Frøkiær, Jørgen; Lundorf, Erik; Pilegaard, Hans K; Hjortdal, Vibeke E

2011-07-25

359

Dielectric elastomer transducers with enhanced force output and work density  

NASA Astrophysics Data System (ADS)

We demonstrate that the force output and work density of polydimethylsiloxane (PDMS) based dielectric elastomer transducers can be significantly enhanced by the addition of high permittivity titanium dioxide nanoparticles. The nanocomposites are capable of maintaining the actuation strain performance of the pure PDMS at relatively low electric fields while increasing the force output and work density due to mechanical reinforcement. A model relating the Maxwell stress to the measured force from the actuator was used to determine the dielectric permittivity at high electric fields thus providing results that can be directly correlated to device performance. This approach toward higher work density materials should enable smaller, lighter, and less intrusive actuator systems ideal for biomedical and robotic devices in particular.

Stoyanov, Hristiyan; Brochu, Paul; Niu, Xiaofan; Della Gaspera, Enrico; Pei, Qibing

2012-06-01

360

A mathematical model for power output in rowing on an ergometer  

Microsoft Academic Search

A mathematical model relating power output of rower to stroke rate on an ergometer (the Concept II Indoor Rower TM, Model\\u000a C) is studied. The model is used to analyse the ergometer performance of a particular rower. It is determined that he can\\u000a be more efficient (i.e. decrease power output while maintaining fixed velocity) by decreasing stroke rate, but at

Scott Gordon

2003-01-01

361

Myoglobin enhances cardiac performance in antarctic icefish species that express the protein.  

PubMed

Channichthyid icefishes of Antarctica are unique among adult vertebrates. All icefish species lack hemoglobin and red blood cells in their circulating blood. All icefishes examined to date also lack the intracellular oxygen-binding protein myoglobin (Mb) in their oxidative skeletal muscles. However, some icefish species do express Mb in their heart ventricles. It is unknown whether Mb in those species in which it is present represents an evolutionary relic or has functional significance. To address this problem, we compared mechanical performance of isolated, perfused hearts from two species of icefish in which Mb is either present (Chionodraco rastrospinosus) or is absent (Chaenocephalus aceratus). Hearts were challenged with increasing afterload (2.5-4.0 kPa) under conditions of defined basal flow (approximately 100 ml.min-1.kg-1), in both the presence and absence of 5 mM sodium nitrite, a Mb poison. Unlike hearts from C. aceratus, which were unable to maintain a constant cardiac output under pressure loading, those from C. rastrospinosus retained a constant flow up to 3.5 kPa afterload. At the upper range of power outputs, hearts of Mb-lacking C. aceratus display greater oxygen utilization than those of Mb-containing C. rastrospinosus. Poisoning of Mb significantly impaired the ability of C. rastrospinosus hearts to face pressure loading without reduction in flow, whereas those of C. aceratus were refractory to the treatment. The results strongly support a functional role for Mb in the former species. PMID:9249538

Acierno, R; Agnisola, C; Tota, B; Sidell, B D

1997-07-01

362

Early goal-directed therapy in moderate to high-risk cardiac surgery patients.  

PubMed

Early goal-directed therapy is a term used to describe the guidance of intravenous fluid and vasopressor/inotropic therapy by using cardiac output or similar parameters in the immediate post-cardiopulmonary bypass in cardiac surgery patients. Early recognition and therapy during this period may result in better outcome. In keeping with this aim in the cardiac surgery patients, we conducted the present study. The study included 30 patients of both sexes, with EuroSCORE >or=3 undergoing coronary artery bypass surgery under cardiopulmonary bypass. The patients were randomly divided into two groups, namely, control and early goal-directed therapy (EGDT) groups. All the subjects received standardized care; arterial pressure was monitored through radial artery, central venous pressure through a triple lumen in the right internal jugular vein, electrocardiogram, oxygen saturation, temperature, urine output per hour and frequent arterial blood gas analysis. In addition, cardiac index monitoring using FloTrac and continuous central venous oxygen saturation using PreSep was used in patients in the EGTD group. Our aim was to maintain the cardiac index at 2.5-4.2 l/min/m2 , stroke volume index 30-65 ml/beat/m2 , systemic vascular resistance index 1500-2500 dynes/s/cm5/m2 , oxygen delivery index 450-600 ml/min/m2 , continuous central venous oximetry more than 70%, stroke volume variation less than 10%; in addition to the control group parameters such as central venous pressure 6-8 mmHg, mean arterial pressure 90-105 mmHg, normal arterial blood gas analysis values, pulse oximetry, hematocrit value above 30% and urine output more than 1 ml/kg/h. The aims were achieved by altering the administration of intravenous fluids and doses of inotropic or vasodilator agents. Three patients were excluded from the study and the data of 27 patients analyzed. The extra volume used (330+/-160 v/s 80+/-80 ml, P=0.043) number of adjustments of inotropic agents (3.4+/-1.5 v/s 0.4+/-0.7, P=0.026) in the EGDT group were significant. The average duration of ventilation (13.8+/-3.2 v/s 20.7+/-7.1 h), days of use of inotropic agents (1.6+/-0.9 v/s 3.8+/-1.6 d), ICU stay (2.6+/-0.9 v/s 4.9+/-1.8 d) and hospital stay (5.6+/-1.2 v/s 8.9+/-2.1 d) were less in the EGDT group, compared to those in the control group. This study is inconclusive with regard to the beneficial aspects of the early goal-directed therapy in cardiac surgery patients, although a few benefits were observed. PMID:18182756

Kapoor, Poonam Malhotra; Kakani, Madhava; Chowdhury, Ujjwal; Choudhury, Minati; Lakshmy; Kiran, Usha

363

X-ray source assembly having enhanced output stability, and fluid stream analysis applications thereof  

DOEpatents

An x-ray source assembly and method of operation are provided having enhanced output stability. The assembly includes an anode having a source spot upon which electrons impinge and a control system for controlling position of the anode source spot relative to an output structure. The control system can maintain the anode source spot location relative to the output structure notwithstanding a change in one or more operating conditions of the x-ray source assembly. One aspect of the disclosed invention is most amenable to the analysis of sulfur in petroleum-based fuels.

Radley, Ian (Glenmont, NY); Bievenue, Thomas J. (Delmar, NY); Burdett, John H. (Charlton, NY); Gallagher, Brian W. (Guilderland, NY); Shakshober, Stuart M. (Hudson, NY); Chen, Zewu (Schenectady, NY); Moore, Michael D. (Alplaus, NY)

2008-06-08

364

Registration for Hemoglobin Standards and Maintaining ...  

Center for Biologics Evaluation and Research (CBER)

... Registration for Hemoglobin Standards and Maintaining Adequate Iron Stores in Blood Donors Public Workshop. Natcher ... More results from www.fda.gov/biologicsbloodvaccines/newsevents/workshopsmeetingsconferences

365

OPTIMIZATION OF A LASERTRON DOUBLE OUTPUT CAVITY  

Microsoft Academic Search

Double output cavities have been used experimentally to increase the effi- ciency of high-power klystrons (l). We have used particle-in-cell simulations with the 2+1\\/2 dimensional code MASK to optimize the design of double output cavities for the lasertron under development at SLAC. We discuss design consid- erations for double output cavities (e.g., optimum choice of voltages and phases, efficiency, wall

K. R. EPPLEY

366

Optimization of a lasertron double output cavity  

Microsoft Academic Search

Double output cavities have been used experimentally to increase the efficiency of high-power klystrons. We have used particle-in-cell simulations with the 2 + 1\\/2 dimensional code MASK to optimize the design of double output cavities for the lasertron under development at SLAC. We discuss design considerations for double output cavities (e.g., optimum choice of voltages and phases, efficiency, wall interception,

K. R. Eppley

1986-01-01

367

Cardiac disease in pregnancy: value of echocardiography.  

PubMed

Cardiovascular disease in women during pregnancy poses particular challenges. It continues to be a leading cause of maternal mortality and contributes to significant morbidity. Echocardiography is essential in characterizing the extent and effects of heart disease prior to, during, and after pregnancy. By understanding the physiologic adaptation in pregnancy with increases in heart rate, blood volume, and cardiac output, and decrease in vascular resistance, one can anticipate and recognize the effects of these changes on various cardiac lesions. Cardiomyopathy, severe, obstructive valvular disease, aortic dilation due to Marfan's disease, and cyanotic congenital heart disease are poorly tolerated in pregnancy. These disorders can be readily distinguished from normal structural changes of pregnancy and their severity assessed by echocardiography. Cardiovascular disease in women of reproductive age requires careful, multidisciplinary management by obstetric and medical teams ideally beginning preconception and continuing through the postpartum period. PMID:20424969

Tsiaras, Sarah; Poppas, Athena

2010-05-01

368

Cointegration of output, capital, labor, and energy  

NASA Astrophysics Data System (ADS)

Cointegration analysis is applied to the linear combinations of the time series of (the logarithms of) output, capital, labor, and energy for Germany, Japan, and the USA since 1960. The computed cointegration vectors represent the output elasticities of the aggregate energy-dependent Cobb-Douglas function. The output elasticities give the economic weights of the production factors capital, labor, and energy. We find that they are for labor much smaller and for energy much larger than the cost shares of these factors. In standard economic theory output elasticities equal cost shares. Our heterodox findings support results obtained with LINEX production functions.

Stresing, R.; Lindenberger, D.; Kã¼mmel, R.

2008-11-01

369

Cardiac sympathetic innervation and cardiac resynchronization therapy.  

PubMed

Cardiac resynchronization therapy (CRT) is a disease modifying, device-driven treatment that can reduce morbidity and mortality in patients with heart failure. According to the current guidelines, the indication for CRT is only based on QRS duration and functional class of heart failure. However, a substantial amount of patients do not respond to therapy. In addition, CRT is accompanied by significant cost and potential morbidity. It is therefore vital to improve patient selection for CRT to improve patient outcome and minimize therapy-related complications. In this regard, cardiac sympathetic innervation may be of interest. This review addresses the currently available literature, 9 studies with a total number of 225 patients, on CRT and cardiac innervation scintigraphy with (123)I-metaiodobenzylguanidine. PMID:23749044

Scholtens, A M; Braat, A J A T; Tuinenburg, A; Meine, M; Verberne, H J

2013-06-01

370

Hybrid Pediatric Cardiac Surgery  

Microsoft Academic Search

Minimally invasive strategies can be expanded by combining standard surgical and interventional techniques. We performed a longitudinal prospective study of all pediatric patients who have undergone hybrid cardiac surgery at the University of Chicago Children's Hospital. Hybrid cardiac surgery was defined as combined catheter-based and surgical interventions in either one setting or in a planned sequential fashion within 24 hours.

E. A. Bacha; Z. M. Hijazi; Q. L. Cao; R. Abdulla; J. P. Starr; J. Quinones; P. Koenig; B. Agarwala

2005-01-01

371

Focal Cardiac Myocytolysis.  

National Technical Information Service (NTIS)

During the course of a clinical pathologic study of cardiac lesions observed in 375 autopsies at ABCC, focal cardiac myocytolysis (FCM) was found in 21 hearts. There was no evidence that FCM was related to prior exposure at the time of the bomb. Myocardia...

A. Steer T. Kawashima T. Nakashima D. S. Dock K. K. Lee

1975-01-01

372

Garfinkel Cardiac Data  

NSDL National Science Digital Library

Cardiac data on multiple variables for a selected population of 220 men and 338 women participating in a drug treatment study of dobutamine for heart attack prevention. Garfinkel, Alan, et. al. "Prognostic Value of Dobutamine Stress Echocardiography in Predicting Cardiac Events in Patients With Known or Suspected Coronary Artery Disease." Journal of the American College of Cardiology 33.3 (1999) 708-16.

Alan Garfinkel (University of California Los Angeles;Physiological Sci/Med-Cardio)

2009-01-10

373

Cardiac risk telemonitoring  

Microsoft Academic Search

Utilization of advanced information, telecommunication and implant technology for cardiac risk stratification and management is one of the greatest challenges for modern health care provision. Sudden cardiac death is the major contributor to overall cardiovascular mortality with approximately 60% of all coronary heart disease fatalities occurring annually. Although some high-risk patient groups have been identified with reasonable sensitivity and specificity

H. Hutten; M. Hribernigg; G. Rauchegger

2001-01-01

374

Cardiac rehabilitation: an overview.  

PubMed

This article provides an overview of the process and application of cardiac rehabilitation following myocardial infarction and coronary artery bypass grafting. The authors discuss risk factor modification targeting smoking, serum cholesterol, hypertension, and exercise training. The role of the physician and the practitioner are addressed as well as the physiological and psychological benefits of cardiac rehabilitation. PMID:1613314

Gremillion, M M; VanHoof, C C; Landreneau, J W

1992-05-01

375

Principles of cardiac anaesthesia  

Microsoft Academic Search

There are a number of accepted anaesthetic techniques for cardiac surgery. New drugs continue to be introduced into clinical practice, and there are differences of opinion about the optimal anaesthetic for a particular cardiac procedure. However, there is evidence that it is not the initial choice of a particular anaesthetic technique or group of drugs that is crucial to outcome,

John W. W. Gothard; Moira Wattie

2006-01-01

376

Cardiac Resynchronization Therapy Upregulates Cardiac Autonomic Control  

PubMed Central

Objective: To determine the effect of cardiac resynchronization therapy (CRT) on sympathetic nervous function in heart failure (HF). Background: Neurohormonal dysregulation and cardiac autonomic dysfunction are associated with HF and contribute to HF progression and its poor prognosis. We hypothesized that mechanical resynchronization improves cardiac sympathetic function in HF. Methods: Sixteen consecutive patients receiving CRT for advanced cardiomyopathy and 10 controls were included in this prospective study. NYHA class, 6-minute walk distance, echocardiographic parameters, plasma norepinephrine (NE) were assessed at baseline, 3-month and 6-month follow-up. Cardiac sympathetic function was determined by 123iodine metaiodobenzylguanidine (123I-MIBG) scintigraphy and 24-hour ambulatory electrocardiography. Results: Along with improvement in NYHA class (3.1 ± 0.3 to 2.1 ± 0.4, P < 0.001) and LVEF (23 ± 6% to 33 ± 12%, P < 0.001 delayed heart/mediastinum (H/M) 123 I-MIBG ratio increased significantly (1.8 ± 0.7 to 2.1 ± 0.6, P = 0.04) while the H/M 123I-MIBG washout rate decreased significantly (54 ± 25% to 34± 24%, P = 0.01) from baseline to 6-month follow-up. The heart rate variability (HRV) measured in SD of normal-to-normal intervals also increased significantly from baseline (82 ± 30 ms) to follow-up (111 ± 32 ms, P = 0.04). The improvement in NYHA after CRT was significantly associated with baseline 123I-MIBG H/M washout rate (r = 0.65, P = 0.03). The improvement in LVESV index was associated with baseline 123I-MIBG delayed H/M ratio (r = ?0.67, P = 0.02) and H/M washout rate (r = 0.65, P = 0.03). Conclusion: After CRT, improvements in cardiac symptoms and LV function were accompanied by rebalanced cardiac autonomic control as measured by 123I-MIBG and HRV.

CHA, YONG-MEI; OH, JAE; MIYAZAKI, CHINAMI; HAYES, DAVID L.; REA, ROBERT F.; SHEN, WIN-KUANG; ASIRVATHAM, SAMUEL J.; KEMP, BRAD J.; HODGE, DAVID O.; CHEN, PENG-SHENG; CHAREONTHAITAWEE, PANITHAYA

2009-01-01

377

The left ventricle as a mechanical engine: from Leonardo da Vinci to the echocardiographic assessment of peak power output-to-left ventricular mass.  

PubMed

The interpretation of the heart as a mechanical engine dates back to the teachings of Leonardo da Vinci, who was the first to apply the laws of mechanics to the function of the heart. Similar to any mechanical engine, whose performance is proportional to the power generated with respect to weight, the left ventricle can be viewed as a power generator whose performance can be related to left ventricular mass. Stress echocardiography may provide valuable information on the relationship between cardiac performance and recruited left ventricular mass that may be used in distinguishing between adaptive and maladaptive left ventricular remodeling. Peak power output-to-mass, obtained during exercise or pharmacological stress echocardiography, is a measure that reflects the number of watts that are developed by 100 g of left ventricular mass under maximal stimulation. Power output-to-mass may be calculated as left ventricular power output per 100 g of left ventricular mass: 100× left ventricular power output divided by left ventricular mass (W/100 g). A simplified formula to calculate power output-to-mass is as follows: 0.222 × cardiac output (l/min) × mean blood pressure (mmHg)/left ventricular mass (g). When the integrity of myocardial structure is compromised, a mismatch becomes apparent between maximal cardiac power output and left ventricular mass; when this occurs, a reduction of the peak power output-to-mass index is observed. PMID:21934524

Dini, Frank L; Guarini, Giacinta; Ballo, Piercarlo; Carluccio, Erberto; Maiello, Maria; Capozza, Paola; Innelli, Pasquale; Rosa, Gian M; Palmiero, Pasquale; Galderisi, Maurizio; Razzolini, Renato; Nodari, Savina

2013-03-01

378

Reuse of permanent cardiac pacemakers.  

PubMed Central

Cardiac pacemakers are part of a growing group of expensive implantable electronic devices; hospitals in which 100 pacemakers are implanted per year must budget over $300 000 for these devices. This cost represents a considerable burden to health care resources. Since the "life-span" of modern pacemakers often exceeds that of the patients who receive them, the recovery and reuse of these devices seems logical. Pacemakers can be resterilized and tested with current hospital procedures. Reuse should be acceptable under Canadian law, but the manner in which the pacemakers are recovered and the patients selected should follow careful guidelines. Every patient should provide written informed consent before receiving a recovered pacemaker. Properly executed, reuse of pacemakers should provide a high level of health care while maintaining or reducing the cost of these devices.

Rosengarten, M D; Portnoy, D; Chiu, R C; Paterson, A K

1985-01-01

379

Women's work. Maintaining a healthy body weight  

Microsoft Academic Search

This study describes women's perceptions of the supports and barriers to maintaining a healthy weight among currently healthy weight women from urban and rural socio-economically disadvantaged areas. Using focus groups and interviews, we asked women about their experiences of maintaining a healthy weight. Overwhelmingly, women described their healthy weight practices in terms of concepts related to work and management. The

Nicky Welch; Wendy Hunter; Karina Butera; Karen Willis; Verity Cleland; David Crawford; Kylie Ball

2009-01-01

380

Methodology for maintainability-based risk assessment  

Microsoft Academic Search

A software product spends more than 65% of its lifecycle in maintenance. Software systems with good maintainability can be easily modified to fix faults or to adapt to changing environment. We define maintainability-based risk as a product of two factors: the probability of performing maintenance tasks and the impact of performing these tasks. In this paper, we present a methodology

Walid M. Abdelmoez; K. Goseva-Popstojanova; H. H. Ammar

2006-01-01

381

An integrated measure of software maintainability  

Microsoft Academic Search

For large software systems, the maintenance phase tends to have comparatively much longer duration than all the previous life-cycle phases taken together, obviously resulting in much more effort. A good measure of software maintainability can help better manage the maintenance phase effort. Software maintainability cannot be adequately measured by only source code or by documents. The readability and understandability of

K. K. Aggarwal; Y. Singh; J. K. Chhabra

2002-01-01

382

Evaluating Software Maintainability Using Fuzzy Entropy Theory  

Microsoft Academic Search

With the development of information technology, a large number of software products enter the maintenance phase. The maintainability of software products continues to attract people's attention. This paper proposes a new synthetic maintainability evaluation model basing on fuzzy entropy theory. In the model, the weight of different indexes is calculated by combining the entropy weight and expert weight. The entropy

Lizhi Cai; Zhenyu Liu; Juan Zhang; Weiqin Tong; Genxing Yang

2010-01-01

383

Accelerating, maintaining and sanctionanting factors of inflation  

Microsoft Academic Search

In order to understand inflation or stagflation in present day oligopolistic capitalism, it is necessary to distinguish the accelerating, the maintaining and the sanctionating factors of inflation. Four are the accelerating factors: change in profit margins, change in real wages above (or below) productivity, changes in the real exchange rate and in the costs of imports. The basic maintaining factors

LUIZ CARLOS BRESSER-PEREIRA; YOSHIAKI NAKANO

1984-01-01

384

Maintaining multiple views in feature modeling  

Microsoft Academic Search

A new feature modeling concept and its implementation are pre- sented. In the multiple-view modeling concept, a set of open fea- ture views of a product is maintained. The implementation does not rely on the existence of certain views, but instead is generic since generic view specifications are used. Views are maintained using feature conversion techniques, in- cluding constraint techniques.

Klaas Jan de Kraker; Maurice Dohmen; Willem F. Bronsvoort

1997-01-01

385

Intentions to Maintain Adherence to Mammography  

Microsoft Academic Search

Objective: Recent attention has focused on moving women from having initial mammograms to maintaining adherence to regular mammography schedules. We examined behavioral intentions to maintain mammogra- phy adherence, which include the likelihood of performing a behavior, and implementation intentions, specific action plans to obtain mammograms. Potential predictors were Theory of Planned Behavior constructs, previ- ous barriers, previous mammography maintenance, and

Suzanne C. O'Neill; J. Michael Bowling; Noel T. Brewer; Isaac M. Lipkus; Celette Sugg Skinner; Tara S. Strigo; Barbara K. Rimer

2010-01-01

386

Encapsulation method for maintaining biodecontamination activity  

DOEpatents

A method for maintaining the viability and subsequent activity of microorganisms utilized in a variety of environments to promote biodecontamination of surfaces. One application involves the decontamination of concrete surfaces. Encapsulation of microbial influenced degradation (MID) microorganisms has shown that MID activity is effectively maintained under passive conditions, that is, without manual addition of moisture or nutrients, for an extended period of time.

Rogers, Robert D. (Idaho Falls, ID); Hamilton, Melinda A. (Idaho Falls, ID); Nelson, Lee O. (Idaho Falls, ID); Benson, Jennifer (Cockermouth, GB); Green, Martin J. (Wooton, GB); Milner, Timothy N. (Centerville, VA)

2002-01-01

387

Variable positive end-expiratory pressure can maintain oxygenation in experimental acute respiratory distress syndrome induced by oleic acid in dogs.  

PubMed

The use of positive end-expiratory pressure (PEEP) or lung recruitment maneuvers (RM) to improve oxygenation in acute respiratory distress syndrome (ARDS) is used but it may reduce cardiac output (CO). Intermittent PEEP may avoid these complications. Our objective was to determine if variable PEEP compared with constant PEEP is capable of maintaining arterial oxygenation and minimizing hemodynamic alterations with or without RM. Eighteen dogs with ARDS induced by oleic acid were randomized into three equal groups: group 1, low variable PEEP; group 2, high variable PEEP, and group 3, RM + high variable PEEP. All groups were submitted to constant PEEP, followed by variable PEEP (PEEP was increased from 5 to 10 cmH(2)O in group 1, and from 5 to 18 cmH(2)O in the other two groups). PaO(2) was higher in group 3 (356.2 +/- 65.4 mmHg) than in group 1 (92.7 +/- 29.7 mmHg) and group 2 (228.5 +/- 72.4 mmHg), P < 0.05. PaO(2) was maintained during variable PEEP except in group 2 (318.5 +/- 82.9 at constant PEEP to 228.5 +/- 72.4 at variable PEEP). There was a reduction in CO in group 3 after RM (3.9 +/- 1.1 before to 2.7 +/- 0.5 L*min(-1)*(m(2))(-1) after; P < 0.05), but there was not any difference between constant and variable PEEP periods (2.7 +/- 0.5 and 2.4 +/- 0.7 L*min(-1)*(m(2))(-1); P > 0.05. Variable PEEP is able to maintain PaO(2) when performed in combination with RM in dogs with ARDS. After RM, CO was reduced and there was no relevant difference between the variable and constant PEEP periods. PMID:19649399

Lanza, F C; Damasceno, M C P; Leme, F; Yagui, A C Z; Paiva, K C; Luque, A; Beppu, O S

2009-08-01

388

Matrix metalloproteinase expression in cardiac myocytes following myocardial infarction in the rabbit  

Microsoft Academic Search

Myocardial infarction (MI), leads to cardiac remodeling, thinning of the ventricle wall, ventricular dilation, and heart failure, and is a leading cause of death. Interactions between the contractile elements of the cardiac myocytes and the extracellular matrix (ECM) help maintain myocyte alignment required for the structural and functional integrity of the heart. Following MI, reorganization of the ECM and the

Anne M. Romanic; Cynthia L. Burns-Kurtis; Bernard Gout; Isabelle Berrebi-Bertrand; Eliot H. Ohlstein

2001-01-01

389

Series Elasticity and Actuator Power Output  

Microsoft Academic Search

In this investigation we put forth a simple model to quantify the capacity of series elasticity to increase peak power output from an actuator. Using a linear bandwidth limited force source, we show how series spring stiffness and source stroke length effect power output to an inertial load. We show that an appropriate spring constant increases the the peak power

Daniel Paluska; Hugh Herr

2006-01-01

390

Estimating Potential Output as a Latent Variable  

Microsoft Academic Search

This article proposes a new method for estimating potential output in which potential real gross domestic product (GDP) is modeled as an unobserved stochastic trend, and deviations of GDP from potential affect inflation through an aggregate supply relationship. The output and inflation equations together form a bivariate unobserved-components model which is estimated via maximum likelihood through the use of the

Kenneth N. Kuttner

1994-01-01

391

Design of hydraulic output Stirling engine  

Microsoft Academic Search

A hydraulic output system for the RE-1000 free piston stirling engine (FPSE) was designed. The hydraulic output system can be readily integrated with the existing hot section of RE-1000 FPSE. The system has two simply supported diaphragms which separate the engine gas from the hydraulic fluid, a dynamic balance mechanism, and a novel, null center band hydraulic pump. The diaphragms

W. M. Toscano; A. C. Harvey; K. Lee

1983-01-01

392

Magnetron with axial output of radiation  

Microsoft Academic Search

As the limiting case of a magnetron with diffraction output [1], we consider a magnetron with axial extraction of electromagnetic energy through a cylindrical waveguide joined to the resonant system. A short length of waveguide with small cross section (less than cut off for the radiated wave) is placed between the resonant system and the output waveguide to obtain the

M. Fuks

2005-01-01

393

Output structure for buried-channel CCD  

Microsoft Academic Search

An output structure for buried-channel charge coupled devices (CCD) is presented which permits output voltage swings of several volts without restricting the design of the buried-channel or requiring excessive drain voltage. Its application to experimental CCD imaging devices is discussed.

E. S. Schlig; S. G. Chamberlain

1984-01-01

394

Output structure for buried-channel CCD  

NASA Astrophysics Data System (ADS)

An output structure for buried-channel charge coupled devices (CCD) is presented which permits output voltage swings of several volts without restricting the design of the buried-channel or requiring excessive drain voltage. Its application to experimental CCD imaging devices is discussed.

Schlig, E. S.; Chamberlain, S. G.

1984-12-01

395

Efficient input—output model representations  

Microsoft Academic Search

A family of multivariate representations is presented to capture the input—output relationships of physical systems with many input variables. The high-dimensional model representations (HDMR) are based on the ansatz that for most physical systems, only relatively low order correlations of the input variables will have an impact on the output. Application of the HDMR tools can dramatically reduce the computational

Herschel Rabitz; Ömer F. Ali?; Jeffrey Shorter; Kyurhee Shim

1999-01-01

396

Altered Cardiac Function and Minimal Cardiac Damage during Prolonged Exercise  

Microsoft Academic Search

SHAVE, R., E. DAWSON, G. WHYTE, K. GEORGE, D. GAZE, and P. COLLINSON. Altered Cardiac Function and Minimal Cardiac Damage during Prolonged Exercise. Med. Sci. Sports Exerc., Vol. 36, No. 7, pp. 1098 -1103, 2004. Purpose: The purpose of the present study was to examine markers of cardiac function and cardiac damage during a simulated half-ironman triathlon in highly trained

ROBERT SHAVE; ELLEN DAWSON; GREGORY WHYTE; KEITH GEORGE; DAVID GAZE; PAUL COLLINSON

2004-01-01

397

Relationship between peak cardiac pumping capability and indices of cardio-respiratory fitness in healthy individuals.  

PubMed

Cardiac power output (CPO) is a unique and direct measure of overall cardiac function (i.e. cardiac pumping capability) that integrates both flow- and pressure-generating capacities of the heart. The present study assessed the relationship between peak exercise CPO and selected indices of cardio-respiratory fitness. Thirty-seven healthy adults (23 men and 14 women) performed an incremental exercise test to volitional fatigue using the Bruce protocol with gas exchange and ventilatory measurements. Following a 40-min recovery, the subjects performed a constant maximum workload exercise test at or above 95% of maximal oxygen consumption. Cardiac output was measured using the exponential CO(2) rebreathing method. The CPO, expressed in W, was calculated as the product of the mean arterial blood pressure and cardiac output. At peak exercise, CPO was well correlated with cardiac output (r = 0·92, P<0·01), stroke volume (r = 0·90, P<0·01) and peak oxygen consumption (r = 0·77, P<0·01). The coefficient of correlation was moderate between CPO and anaerobic threshold (r = 0·47, P<0·01), oxygen pulse (r = 0·57, P<0·01), minute ventilation (r = 0·53, P<0·01) and carbon dioxide production (r = 0·56, P<0·01). Small but significant relationship was found between peak CPO and peak heart rate (r = 0·23, P<0·05). These findings suggest that only peak cardiac output and stroke volume truly reflect CPO. Other indices of cardio-respiratory fitness such as oxygen consumption, anaerobic threshold, oxygen pulse, minute ventilation, carbon dioxide production and heart rate should not be used as surrogates for overall cardiac function and pumping capability of the heart. PMID:22856346

Jakovljevic, Djordje G; Popadic-Gacesa, Jelena Z; Barak, Otto F; Nunan, David; Donovan, Gay; Trenell, Michael I; Grujic, Nikola G; Brodie, David A

2012-04-25

398

The dynamic pattern of end-tidal carbon dioxide during cardiopulmonary resuscitation: difference between asphyxial cardiac arrest and ventricular fibrillation\\/pulseless ventricular tachycardia cardiac arrest  

Microsoft Academic Search

INTRODUCTION: Partial pressure of end-tidal carbon dioxide (PetCO2) during cardiopulmonary resuscitation (CPR) correlates with cardiac output and consequently has a prognostic value in CPR. In our previous study we confirmed that initial PetCO2 value was significantly higher in asphyxial arrest than in ventricular fibrillation\\/pulseless ventricular tachycardia (VF\\/VT) cardiac arrest. In this study we sought to evaluate the pattern of PetCO2

Katja Lah; Miljenko Križmari?; Štefek Grmec

2011-01-01

399

Cardiac electrophysiology in diabetes.  

PubMed

Patients with diabetes mellitus are at higher risk of cardiac arrhythmias and sudden death. Although there are several animal and human studies on this topic, the pathophysiology of the increased electrical vulnerability in diabetes is complex and remain undefined. It is conceivable that an interplay of several concomitant factors may facilitate the occurrence of arrhythmias. Atherosclerosis as well as microvascular disease, which are increased in diabetic patients, may facilitate myocardial ischemia that predisposes to cardiac arrhythmias and sudden death. In addition, autonomic neuropathy and/or cardiac repolarization abnormalities such as prolonged QT interval and altered T-waves of the diabetic heart also increases electrical instability. Therefore, all these factors may simultaneously contribute to create an electrical instability leading to cardiac arrhythmias and sudden cardiac death. Recently, we have demonstrated that diabetes is the strongest predictor of atrial fibrillation (AF) progression and that diabetic patients frequently have asymptomatic episodes of AF with silent arrhythmia progression. Another recent study has reported that patients with type 2 diabetes and AF are at substantially higher risk of death of any cause compared with those without AF. These seminal studies emphasize that AF in diabetic patients should be regarded as a prognostic marker of adverse outcome and then a prompt aggressive management of all risk factors is required. In conclusion, diabetes mellitus significantly alters the cardiac electrophysiology throughout several complex mechanisms greatly contributing to create an electrical instability of the heart, which may lead to potentially life-threatening arrhythmias and sudden cardiac death. PMID:20440255

Pappone, C; Santinelli, V

2010-04-01

400

Naturally occurring cardiac glycosides.  

PubMed

Cardiac glycoside poisoning from the ingestion of plants, particularly of oleanders, occurs with reasonable frequency in tropical and subtropical areas. We have assessed a variety of plant specimens for their cardiac glycoside content by means of radioimmunoassays with antibodies that differ in their specificity for cardiac glycosides. Significant amounts of immunoreactive cardiac glycoside were found to be present in the ornamental shrubs: yellow oleander (Thevetia peruviana); oleander (Nerium oleander); wintersweet (Carissa spectabilis); bushman's poison (Carissa acokanthera); sea-mango (Cerbera manghas); and frangipani (Plumeria rubra); and in the milkweeds: redheaded cotton-bush (Asclepias curassavica); balloon cotton (Asclepias fruiticosa); king's crown (Calotropis procera); and rubber vine (Cryptostegia grandifolia). The venom gland of the cane toad (Bufo marinus) also contained large quantities of cardiac glycosides. The competitive immunoassay method permits the rapid screening of specimens that are suspected to contain cardiac glycosides. Awareness of the existence of these plant and animal toxins and their dangers allows them to be avoided and poisoning prevented. The method is also useful for the confirmation of the presence of cardiac glycosides in serum in cases of poisoning. PMID:3086679

Radford, D J; Gillies, A D; Hinds, J A; Duffy, P

1986-05-12

401

Sudden cardiac death  

Microsoft Academic Search

Opinion statement  \\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a Great strides have been made in the approach to the management of sudden cardiac death. Patients who have been successfully\\u000a resuscitated from an episode of sudden cardiac death are at high risk of recurrence. Much larger groups of patients who have\\u000a not had episodes of sudden cardiac death are also at substantial risk for this event, however.

Jeffrey J. Goldberger

1999-01-01

402

Robust LED backlight driver with low output voltage drop and hig output current accuracy  

Microsoft Academic Search

Constant current regulator for LED backlight system is more and more popular. Some methods are proposed to achieve low voltage drop on output power MOSFET. However, inaccurate output current due to channel length modulation or the oscillation phenomenon of the output current due to instability may occur. In this paper, we analyze the conventional LED driver and disclose the reasons

Tse-Ju Liao; Chern-Lin Chen

2008-01-01

403

Minimum Variance Control of Constant Power Output For Wind Energy Conversion System Above Rated Wind  

Microsoft Academic Search

When the wind speed is above the rated value, pitch angle is regulated to maintain the constant power output in order to limit the wind turbine speed and power because of the mechanical load limit of the mechanical structure and the electric load limit of the electric components. After the mathematical model for the wind energy conversion system and the

Zhao Liang; Chen Bei; Lu Jianhong

2010-01-01

404

NITROGEN OUTPUTS FROM FECAL AND URINE DEPOSITION OF SMALL MAMMALS: IMPLICATIONS FOR NITROGEN CYCLING  

EPA Science Inventory

The contribution of small mammals to nitrogen cycling is poorly understood, but it could have reverberations back to the producer community by maintaining or perhaps magnifying nitrogen availability. Our objective was to model nitrogen outputs (deposition of feces and urine) of ...

405

PV Output Power Fluctuations Smoothing and Optimum Capacity of Energy Storage System for PV Power Generator  

Microsoft Academic Search

In this paper, an Energy Storage System (ESS) based control method is proposed to reduce the PV output power fluctuations, which in turn will reduce the frequency deviations of the power system introduced by large penetration of PV power. The ESS control model introduced here will maintain the energy storage ratio of the ESS near 50%. This will increase the

Tomonobu Senjyu; Manoj Datta; Atsushi Yona; Toshihisa Funabashi; Chul-Hwan Kim

406

Design for Maintainability. An Intricate Simplicity.  

National Technical Information Service (NTIS)

Aircraft maintenance, when analyzed from an operator's point of view, will yield basic maintainability requirements which can be translated into general guidelines for design. The simple picture is greatly complicated when specific conclusions are to be d...

J. Heyligers

1973-01-01

407

Statistical Aspects of Reliability, Maintainability, and Availability.  

National Technical Information Service (NTIS)

The research performed under this grant developed theory, concepts, and methods in reliability, availability, and maintainability, applicable or potentially applicable to the programs of the U.S. Air Force in particular and the Department of Defense in ge...

H. Doss F. Proschan M. Hollander

1991-01-01

408

An Introduction to Reliability and Maintainability.  

ERIC Educational Resources Information Center

|Discusses the need to include studies of reliability and maintainability during the design of any system. Topic areas addressed include availability calculations, complex systems and standby redundancy, availability and malfunction levels, design techniques, fault trees, functional maintenance, and others. (DH)|

Berridge, C. R.

1984-01-01

409

Handbook for Reliability and Maintainability Monitors.  

National Technical Information Service (NTIS)

Each section of this handbook deals with a particular problem area in (Reliability and Maintainability) matters and suggests methods of initiating and operating an R/M program. The material covered ranges from the basic elements of establishing a program ...

G. Grippo G. H. Allen J. E. Horowitz J. R. Barton R. M. DeMilia

1964-01-01

410

Maintaining the Ethical Advantage in Counterinsurgency Operations.  

National Technical Information Service (NTIS)

To conduct effective operations that link tactical victories with achieving strategic goals, a Joint Task Force (JTF) commander should maintain ethical considerations at the forefront of all leadership, planning, and execution efforts to ensure ultimate s...

G. R. Guenther

2005-01-01

411

Maintainability Prediction and Analysis Study. Revision A.  

National Technical Information Service (NTIS)

Existing maintainability prediction techniques are not accurate estimators of current electronic equipment/system characteristics. A new time synthesis prediction technique is developed which directly relates diagnostic/isolation/test subsystem characteri...

F. L. Jew J. E. Angus T. F. Pliska

1978-01-01

412

Myocardial metabolism during hypoxia: Maintained lactate oxidation during increased glycolysis  

SciTech Connect

In the intact animal, myocardial lactate utilization and oxidation during hypoxia are not well understood. Nine dogs were chronically instrumented with flow probes on the left anterior descending coronary artery and with a coronary sinus sampling catheter. ({sup 14}C)lactate and ({sup 13}C)glucose tracers, or ({sup 13}C)lactate and ({sup 14}C)glucose were administered to quantitate lactate and glucose oxidation, lactate conversion to glucose, and simultaneous lactate extraction and release. The animals were anesthetized and exposed to 90 minutes of severe hypoxia (PO2 = 25 +/- 4 torr). Hypoxia resulted in significant increases in heart rate, cardiac output and myocardial blood flow, but no significant change in myocardial oxygen consumption. The arterial/coronary sinus differences for glucose and lactate did not change from normoxia to hypoxia; however, the rate of glucose uptake increased significantly due to the increase in myocardial blood flow. Tracer-measured lactate extraction did not decrease with hypoxia, despite a 250% increase in lactate release. During hypoxia, 90% +/- 4% of the extracted {sup 14}C-lactate was accounted for by the appearance of {sup 14}CO{sub 2} in the coronary sinus, compared with 88% +/- 4% during normoxia. Thus, in addition to the expected increase in glucose uptake and lactate production, we observed an increase in lactate oxidation during hypoxia.

Mazer, C.D.; Stanley, W.C.; Hickey, R.F.; Neese, R.A.; Cason, B.A.; Demas, K.A.; Wisneski, J.A.; Gertz, E.W. (Univ. of California, San Francisco (USA))

1990-09-01

413

Desktop micro-CT with a nanotube field emission x-ray source for high-resolution cardiac imaging  

NASA Astrophysics Data System (ADS)

We have previously reported the development of a dynamic micro-CT scanner with a stationary mouse bed using a compact carbon nanotube (CNT) field emission x-ray tube and preliminary results on its utility for prospectively gated cardiac imaging. In this paper we report the recent progress in improving the performance characteristics of this scanner. Through optimization of the CNT cathode, the stable emission current has been increased. The output power of the CNT x-ray source has reached ~100W peak power at 100?m focal spot size. The higher flux enables improvement of the xray energy spectrum to minimize the beam hardening effect and increasing the system temporal resolution by using shorter x-ray exposure time. The scanner's temporal resolution has been increased to ~10 msec, which is sufficient for high-resolution micro-CT imaging of mouse heart and lung under free-breathing setting. The spatial resolution is maintained at 6.2 lp per mm at 10% system MTF. The nanotube micro-CT scanner's application in mouse cardiac imaging has been demonstrated with high-resolution (80 ?m and 15 msec) micro-CT of the mouse heart under freebreathing setting.

Cao, Guohua; Calderon-Colon, Xiomara; Burk, Laurel; Lee, Yueh Z.; Sultana, Shabana; Lu, Jianping; Zhou, Otto

2010-03-01

414

Ultrabroadband efficient intracavity XUV output coupler.  

PubMed

We report an efficient intracavity XUV output coupler based on an anti-reflection-coated grazing incidence plate (GIP). Conceptually, GIP is an extension of a Brewster plate, affording low loss of the circulating fundamental light and serving as a highly efficient, extremely broadband output coupler for XUV. Due to the grazing incidence geometry, the short wavelength reflectivity can be extended to the keV range. The first GIP realized shows parameters close to the design. We discuss both the limitations of the GIP in comparison with other XUV output couplers and the applicability of the GIP extension at longer wavelengths, down to the MIR. PMID:21643281

Pronin, Oleg; Pervak, Vladimir; Fill, Ernst; Rauschenberger, Jens; Krausz, Ferenc; Apolonski, Alexander

2011-05-23

415

High Energy Output Marx Generator Design  

SciTech Connect

High Energy Output Marx Generator Design a design of a six stage Marx generator that has a unipolar pulse waveform of 200 kA in a 50×500 microsecond waveform is presented. The difficulties encountered in designing the components to withstand the temperatures and pressures generated during the output pulse are discussed. The unique methods and materials used to successfully overcome these problems are given. The steps necessary to increase the current output of this Marx generator design to the meg-ampere region or higher are specified.

Monty Lehmann

2011-07-01

416

Modulation of Cardiac Gap Junction Expression and Arrhythmic Susceptibility  

Microsoft Academic Search

Connexin43 (Cx43), the predominant ventricular gap junction protein, is critical for maintaining normal cardiac electrical conduction, and its absence in the mouse heart results in sudden arrhythmic death. The mechanisms linking reduced Cx43 abundance in the heart and inducibility of malignant ventricular arrhythmias have yet to be established. In this report, we investigate arrhythmic susceptibility in a murine model genetically

Stephan B. Danik; Fangyu Liu; Jie Zhang; H. Jacqueline Suk; Gregory E. Morley; Glenn I. Fishman; David E. Gutstein

2010-01-01

417

Primary Cardiac Angiofibroma  

PubMed Central

Cardiac Angiofibroma is an uncommon intracardiac tumor. Thus far, only 4 cases of the rare intracardiac tumor have been reported. The present case-report describes an intracardiac angiofibroma in a 57-year-old healthy female. The patient was incidentally diagnosed with a left ventricle mass during echocardiography. We performed cardiac imaging, surgical excision and histological evaluation of the mass. The angiofibroma demonstrated features different from the relatively common cardiac tumors such as fibroma, myxoma and angiosarcoma. The cardiac MRI showed slightly high signal intensity on both T1 and T2, with the central core of lower signal intensity. The resected tumor was a whitish and rubbery mass. Histologically, the tumor showed the benign vascular proliferations associated with the surrounding collagen deposition.

Kim, Young Ju; Kim, Young Jin; Kim, Se Hoon; Youn, Young-Nam

2013-01-01

418

Cardiac Arrhythmia Treatment Methods.  

National Technical Information Service (NTIS)

Disclosed are methods of preventing or treating cardiac arrhythmia. In one embodiment, the methods include administering to an amount of at least one polynucleotide that modulates an electrical property of the heart. The methods have a wide variety of imp...

E. Marban J. K. Donahue

2004-01-01

419

Cardiac muscle cells  

NSDL National Science Digital Library

Cardiac muscles are found only in the heart. They work together to bring deoxygenated blood in and push oxygenated blood out into the body. Essentially, they keep your heart pumping and your body alive.

Nathanael Reveal (None;)

2007-07-02

420

Integrative Cardiac Health Project.  

National Technical Information Service (NTIS)

The Integrative Cardiac Health Project (ICHP) aims to lead the way in Cardiovascular Disease (CVD) Prevention by conducting novel research utilizing a Systems Biology / personalized medicine design to discover and develop practical, effective and preempti...

A. H. Nixon M. N. Vernalis

2013-01-01

421

Integrative Cardiac Health Project.  

National Technical Information Service (NTIS)

The Integrative Cardiac Health Project (ICHP) aims to lead the way in Cardiovascular Disease (CVD) Prevention by conducting novel research utilizing a Systems Biology / personalized medicine design to discover and develop practical, effective and preempti...

A. H. NIxon M. N. Vernalis

2011-01-01

422

Sleep and Cardiac Arrhythmias.  

National Technical Information Service (NTIS)

The frequency of cardiac arrhythmias in wake and sleep was studied in 20 patients admitted to a coronary care unit. No significant differences were found for the distribution of ventricular premature contractions or atrial premature contractions in either...

R. Smith L. Johnson D. Rothfield L. Zir B. Tharp

1972-01-01

423

Cardiac tamponade presenting as an apparent life-threatening event.  

PubMed

The initial emergency department (ED) evaluation of infants with an apparent life-threatening event (ALTE) often fails to identify a definitive cause for the event. Many children that present with an ALTE appear normal by the time they arrive to the ED. These factors can desensitize clinicians into prematurely discounting serious underlying causes of the ALTE or being less prompt in their evaluation of these patients. We present the case of a young infant who presented to an ED with an ALTE resulting from cardiac tamponade. Cardiac tamponade has not been reported as an underlying cause of infants presenting to the ED with an ALTE. Previously reported cases of cardiac tamponade in children have occurred as a complication of malignancies, cardiac surgery, trauma, infections, central venous catheter placement, rheumatologic, and autoimmune diseases. This case should serve as a reminder to clinicians to maintain a broad differential diagnosis and promptly evaluate all infants presenting with an ALTE. PMID:15699820

Cousineau, Allison; Savitsky, Eric

2005-02-01

424

[Cerebral oximetry: clinical importance for cardiac surgery patients].  

PubMed

The determination of cerebral oxygen saturation (S(c)O(2)) by means of near-infrared spectroscopy allows non-invasive assessment of the cerebral oxygen delivery and demand ratio in the frontal cortex region. Studies in cardiac as well as non-cardiac patients have shown that maintaining S(c)O(2) in the preoperative range reduces the incidence of postoperative cognitive dysfunction and general morbidity; however, S(c)O(2) is not only reflective of cerebral but also of systemic oxygen balance, is inversely related to cardiopulmonary function and has prognostic relevance in cardiac surgery patients. This suggests that cerebral oximetry is not only useful for neurological but also for hemodynamic monitoring and preoperative risk stratification of cardiac surgery patients. PMID:22965180

Schön, J; Paarmann, H; Heringlake, M

2012-09-12

425

Minimally invasive cardiac surgery  

Microsoft Academic Search

Cardiac surgery has been the last of the surgical specialties to embrace the principles of minimal invasiveness. The complexity\\u000a and invasiveness of the procedures have presented both a problem and an opportunity to make the procedures less invasive.\\u000a Beginning with initial attempts at coronary artery bypass surgery through limited access with and without robotics, a number\\u000a of other cardiac procedures

M. J. Mack

2006-01-01

426

Primary cardiac osteosarcoma  

Microsoft Academic Search

Primary cardiac neoplasms are an infrequent disease, as most of the tumors arising in the heart are metastatic. Between the\\u000a malignant tumors, sarcomas are the most frequent ones, accounting for at least 95% of them. We report the case of a 70-year\\u000a old woman, diagnosed of primary cardiac osteosarcoma arising in the left atrium. Although complete excision of the tumor

María López; Álvaro Pinto; Víctor Moreno; Marta Díaz; Manuel González Barón

2008-01-01

427

Imaging cardiac fat.  

PubMed

Ectopic fat deposition has been associated with lipotoxicity and derangement in local and systemic metabolism, insulin resistance, cardiac dysfunction, atherosclerosis, local, and systemic inflammation. The mechanisms and potentially detrimental effects of such an accumulation should be fully investigated in order to establish preventive strategies. The aim of this review is to provide an overview of current knowledge regarding imaging techniques to measure cardiac fat deposition and its potential clinical relevance, if any. PMID:23539476

Davidovich, Daniel; Gastaldelli, Amalia; Sicari, Rosa

2013-03-28

428

Cardiac Arrest in Schools  

Microsoft Academic Search

Background—The purpose of the present study is to improve understanding of the epidemiology of cardiac arrest in the school setting, with a special focus on the role of school-based automated external defibrillators. Methods and Results—The investigation was a retrospective study of emergency medical service-treated, nontraumatic, out-of-hospital cardiac arrests in Seattle and King County, Washington, that occurred in schools between 1990

Katayoun Lotfi; Lindsay White; Tom Rea; Leonard Cobb; Michael Copass; Lihua Yin; Linda Becker; Mickey Eisenberg

2009-01-01

429

Cardiac Mapping Technology  

Microsoft Academic Search

\\u000a In general, the methodologies for cardiac electrical mapping entail registration of the electrical activation sequences of\\u000a the heart by recording extracellular electrograms. The initial use of cardiac mapping was primarily to better understand the\\u000a normal electrical excitations of the heart. However, the focus in mapping over time has shifted to the study of mechanisms\\u000a and substrates underlying various arrhythmias; these

Nicholas D. Skadsberg; Bin He; Timothy G. Laske; Paul A. Iaizzo

430

Constancy and variability in the output of a central pattern generator  

PubMed Central

Experimental and corresponding modeling studies have demonstrated a 2–5 fold variation of intrinsic and synaptic parameters across animals, while functional output is maintained. These studies have led to the hypothesis that correlated, compensatory changes in particular parameters can at least partially explain the biological variability in parameters. Using the leech heartbeat CPG, we selected three different segmental motor neurons that fire in a functional phase progression but receive input from the same four premotor interneurons. Previous work suggested that the phase progression arises because the pattern of relative strength of the four inputs varies systematically across the segmental motor neurons. Nevertheless, there was considerable animal-to-animal variation in the absolute strengths of these connections. We tested the hypothesis that functional output is maintained in the face of variation in the absolute strength of connections because relative strengths onto particular motor neurons are maintained. We found relative strength is not strictly maintained across animals even as functional output is maintained, and animal-to-animal variations in relative strength of particular inputs do not correlate strongly with output phase. In parallel with this variation in synaptic strength, the firing phase of the premotor inputs to these motor neurons varies considerably across individuals. We conclude that the number (four) of inputs to each motor neuron, which each vary in strength, and the phase diversity of the temporal pattern of input from the CPG diminish the influence of individual inputs. We hypothesize that each animal arrives at a unique solution for how the network produces functional output.

Norris, Brian J.; Wenning, Angela; Wright, Terrence Michael; Calabrese, Ronald L.

2011-01-01

431

Linkage Between Environmental Outputs and Human Services.  

National Technical Information Service (NTIS)

The objectives of the work unit are to: (1) identify relevant socioeconomic use and nonuse values associated with environmental projects; (2) improve the linkages between environmental output measures and necessary inputs for socioeconomic evaluation; (3)...

R. A. Cole J. B. Loomis T. D. Feather D. T. Capan

1996-01-01

432

Output Performance of Idealized Microwave Power Amplifiers.  

National Technical Information Service (NTIS)

Output power, efficiency, power dissipation and optimum load resistance expressions for idealized microwave class A and class B power amplifiers are derived based on a waveform analysis. The effects of device transconductance variation with bias and circu...

L. J. Kushner

1989-01-01

433

Switching Inverter with Sine-Wave Output.  

National Technical Information Service (NTIS)

A relatively simple method of obtaining a multiple-stepped sine-wave output using semiconductor devices as switches was developed. This circuit employs Triacs as power switches, requiring approximately one-fourth the number of switches normally required b...

J. M. Marzolf

1970-01-01

434

Coupling output of multichannel high power microwaves  

SciTech Connect

The coupling output of multichannel high power microwaves is a promising technique for the development of high power microwave technologies, as it can enhance the output capacities of presently studied devices. According to the investigations on the spatial filtering method and waveguide filtering method, the hybrid filtering method is proposed for the coupling output of multichannel high power microwaves. As an example, a specific structure is designed for the coupling output of S/X/X band three-channel high power microwaves and investigated with the hybrid filtering method. In the experiments, a pulse of 4 GW X band beat waves and a pulse of 1.8 GW S band microwave are obtained.

Li Guolin; Shu Ting; Yuan Chengwei; Zhang Jun; Yang Jianhua; Jin Zhenxing; Yin Yi; Wu Dapeng; Zhu Jun; Ren Heming; Yang Jie [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2010-12-15

435

Acupuncture effects on cardiac functions measured by cardiac magnetic resonance imaging in a feline model.  

PubMed

The usefulness of acupuncture (AP) as a complementary and/or alternative therapy in animals is well established but more research is needed on its clinical efficacy relative to conventional therapy, and on the underlying mechanisms of the effects of AP. Cardiac magnetic resonance imaging (CMRI), an important tool in monitoring cardiovascular diseases, provides a reliable method to monitor the effects of AP on the cardiovascular system. This controlled experiment monitored the effect electro-acupuncture (EA) at bilateral acupoint Neiguan (PC6) on recovery time after ketamine/xylazine cocktail anesthesia in healthy cats. The CMRI data established the basic feline cardiac function index (CFI), including cardiac output and major vessel velocity. To evaluate the effect of EA on the functions of the autonomic nervous and cardiovascular systems, heart rate, respiration rate, electrocardiogram and pulse rate were also measured. Ketamine/xylazine cocktail anesthesia caused a transient hypertension in the cats; EA inhibited this anesthetic-induced hypertension and shortened the post-anesthesia recovery time. Our data support existing knowledge on the cardiovascular benefits of EA at PC6, and also provide strong evidence for the combination of anesthesia and EA to shorten post-anesthesia recovery time and counter the negative effects of anesthetics on cardiac physiology. PMID:18955311

Lin, Jen-Hsou; Shih, Chen-Haw; Kaphle, Krishna; Wu, Leang-Shin; Tseng, Weng-Yih; Chiu, Jen-Hwey; Lee, Tzu-Chi; Wu, Ying-Ling

2008-01-23

436

Input-Output-to-State Stability  

Microsoft Academic Search

This work explores Lyapunov characterizations of the input-output-to-state stability (IOSS) property for nonlinear systems. The notion of IOSS is a natural generalization of the standard zero-detectability property used in the linear case. The main contribution of this work is to establish a complete equivalence between the input-output-to-state stability property and the existence of a certain type of smooth Lyapunov function.

Mikhail Krichmanand; Eduardo D. Sontag; Yuan Wang

1999-01-01

437

Input-Output-to-State Stability  

Microsoft Academic Search

This work explores Lyapunov characterizations of the input-output-to-state stability (ioss) property for nonlinear systems. The notion of ioss is a natural generalization of the standard zero-detectability property used in the linear case. The main contribution of this work is to establish a complete equivalence between the input-output-to-state stability property and the existence of a certain type of smooth Lyapunov function.

Mikhail Krichman; Eduardo D. Sontag; Yuan Wang

2001-01-01

438