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Sample records for mechanical chest compressions

  1. Mechanical chest compression: an alternative in helicopter emergency medical services?

    PubMed

    Gässler, Holger; Kümmerle, Simone; Ventzke, Marc-Michael; Lampl, Lorenz; Helm, Matthias

    2015-09-01

    Mechanical chest compression devices are mentioned in the current guidelines of the European Resuscitation Council (ERC) as an alternative in long-lasting cardiopulmonary resuscitations (CPR) or during transport with ongoing CPR. We compared manual chest compression with mechanical devices in a rescue-helicopter-based scenario using a resuscitation manikin. Manual chest compression was compared with the mechanical devices LUCAS™ 2, AutoPulse™ and animax mono (10 series each) using the resuscitation manikin AmbuMan MegaCode Wireless, which was intubated endotracheally and controlled ventilated during the entire scenario. The scenario comprised the installation of each device, transport and loading phases, as well as a 10-min phase inside the helicopter (type BK 117). We investigated practicability as well as measured compression quality. All mechanical devices could be used readily in a BK 117 helicopter. The LUCAS 2 group was the only one that fulfilled all recommendations of the ERC (frequency 102 ± 0.1 min(-1), compression depth 54 ± 3 mm, hands-off time 2.5 ± 1.6 %). Performing adequate manual chest compression was barely possible (fraction of correct compressions 21 ± 15 %). In all four groups, the total hands-off time was <10 %. Performing manual chest compressions during rescue-helicopter transport is barely possible, and only of poor quality. If rescuers are experienced, mechanical chest compression devices could be good alternatives in this situation. We found that the LUCAS 2 system complied with all recommendations of ERC guidelines, and all three tested devices worked consistently during the entire scenario.

  2. Mountain rescue cardiopulmonary resuscitation: a comparison between manual and mechanical chest compressions during manikin cardio resuscitation.

    PubMed

    Thomassen, Oyvind; Skaiaa, Sven Christjar; Assmuss, Jorg; Østerås, Øyvind; Heltne, Jon Kenneth; Wik, Lars; Brattebo, Guttorm

    2017-09-01

    Chest compression devices are useful during mountain rescue but may cause a delay in transport if not immediately available. The aims of this prospective observational study were to compare manual and mechanical cardiopulmonary resuscitation (CPR) during transport on a sledge connected to a snowmobile with a non-moving setting and to compare CPR quality between manual and two mechanical chest compression devices. Sixteen healthcare providers simulated four different combined CPR scenarios on a sledge in a non-moving setting and during transport and two mechanical chest compression devices during transport on the sledge. The study was conducted in May 2015 in a mountain in Norway. The primary outcome measures were compression rate (compressions per minute), compression depth in millimetres, leaning (incomplete chest wall release after compression in millimetres) and chest compression fraction (fraction of total time were compression were performed). The results were analysed by descriptive and graphical methods and paired t-tests were used to compare the differences between techniques. We did not observe a significant difference between moving and non-moving conditions with respect to manual compression rate (p=0.34), compression depth (p=0.50) or leaning (p=0.92). However, both the manual compression depth (p<0.001) and the leaning (p=0.04) showed a significantly larger variance during the moving runs. Manual chest compression is possible on a snowmobile during transport even in challenging terrain. This experimental study shows that high-quality chest compressions and manual ventilation can be performed in an intubated patient during a short-term transportation on a sledge. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  3. [The use of mechanical chest compression devices for both out-of-hospital and in-hospital refractory cardiac arrest].

    PubMed

    Russo, Alessandra; Gasparetto, Nicola; Favero, Luca; Caico, Salvatore Ivan; Orazio, Silvia; Garzena, Guido; Rosi, Paolo; Olivari, Zoran

    2017-04-01

    The purpose of cardiopulmonary resuscitation after sudden cardiac arrest is to restore minimal blood flow to provide oxygen to the brain and other vital organs. Chest compressions and external defibrillation are the first line for circulatory support. Although early defibrillation is the main factor influencing survival, cardiopulmonary resuscitation must be characterized by high-quality external chest compressions. Unfortunately, the performance of manual chest compressions decreases during time and in hostile conditions. For these reasons, mechanical devices for chest compression are able to support rescuers during cardiopulmonary resuscitation. Commonly used mechanical chest compression devices in Europe include LUCAS and Autopulse. Routine utilization of mechanical chest compression devices cannot be recommended because randomized controlled trials, such as LINC and PARAMEDIC for LUCAS and CIRC for Autopulse, have not demonstrated their superiority compared with manual chest compressions. The aim of this review is to analyze recent data regarding utilization of mechanical chest compression devices, and to clarify advantages and limitations.

  4. Assessment of CPR interruptions from transthoracic impedance during use of the LUCAS™ mechanical chest compression system.

    PubMed

    Yost, Dana; Phillips, Reid H; Gonzales, Louis; Lick, Charles J; Satterlee, Paul; Levy, Michael; Barger, Joseph; Dodson, Pamela; Poggi, Stephen; Wojcik, Karen; Niskanen, Robert A; Chapman, Fred W

    2012-08-01

    Quality of cardiopulmonary resuscitation (CPR) is a key determinant of outcome following out-of-hospital cardiac arrest (OHCA). Recent evidence shows manual chest compressions are typically too shallow, interruptions are frequent and prolonged, and incomplete release between compressions is common. Mechanical chest compression systems have been developed as adjuncts for CPR but interruption of CPR during their use is not well documented. Analyze interruptions of CPR during application and use of the LUCAS™ chest compression system. 54 LUCAS 1 devices operated on compressed air, deployed in 3 major US emergency medical services systems, were used to treat patients with OHCA. Electrocardiogram and transthoracic impedance data from defibrillator/monitors were analyzed to evaluate timing of CPR. Separately, providers estimated their CPR interruption time during application of LUCAS, for comparison to measured application time. In the 32 cases analyzed, compressions were paused a median of 32.5s (IQR 25-61) to apply LUCAS. Providers' estimates correlated poorly with measured pause length; pauses were often more than twice as long as estimated. The average device compression rate was 104/min (SD 4) and the average compression fraction (percent of time compressions were occurring) during mechanical CPR was 0.88 (SD 0.09). Interruptions in chest compressions to apply LUCAS can be <20s but are often much longer, and users do not perceive pause time accurately. Therefore, we recommend better training on application technique, and implementation of systems using impedance data to give users objective feedback on their mechanical chest compression device use. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  5. Mechanical chest compressions improved aspects of CPR in the LINC trial.

    PubMed

    Esibov, Alexander; Banville, Isabelle; Chapman, Fred W; Boomars, René; Box, Martyn; Rubertsson, Sten

    2015-06-01

    We studied resuscitation process metrics in patients with out-of-hospital cardiac arrest enrolled in a randomized trial comparing one protocol designed to best use a mechanical CPR device, with another based on the 2005 European Resuscitation Council guidelines for manual CPR. We analyzed clinical data, ECG signals, and transthoracic impedance signals for a subset of the patients in the LUCAS in Cardiac Arrest (LINC) trial, including 124 patients randomized to mechanical and 82 to manual CPR. Chest compression fraction (CCF) was defined as the fraction of time during cardiac arrest that chest compressions were administered. Patients in the mechanical CPR group had a higher CCF than those in the manual CPR group [0.84 (0.78, 0.91) vs. 0.79 (0.70, 0.86), p < 0.001]. The median duration of their pauses for defibrillation was also shorter [0 s (0, 6.0) vs. 10.0 s (7.0, 14.3), p < 0.001]. Compressions were interrupted for a median of 36.0 s to apply the compression device. There was no difference between groups in duration of the longest pause in compressions [32.5s vs. 26.0 s, p = 0.24], number of compressions received per minute [86.5 vs. 88.3, p = 0.47], defibrillation success rate [73.2% vs. 81.0%, p = 0.15], or refibrillation rate [74% vs. 77%, p = 0.79]. A protocol using mechanical chest compression devices reduced interruptions in chest compressions, and enabled defibrillation during ongoing compressions, without adversely affecting other resuscitation process metrics. Future emphasis on optimizing device deployment may be beneficial. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  6. A comparison of prolonged manual and mechanical external chest compression after cardiac arrest in dogs.

    PubMed

    Wik, L; Bircher, N G; Safar, P

    1996-10-01

    The effects of manual and a new mechanical chest compression device (Heartsaver 2000) during prolonged CPR with respect to haemodynamics and outcome were tested in a prospective, randomized, controlled experimental trial during ventricular fibrillation in 12 dogs of 9-13 kg body weight after 1 min of cardiac arrest. During the first 10 min of CPR the dogs were resuscitated according to the Basic Life Support (BLS) algorithm, followed by 20 min of Advanced Life Support (ALS) algorithm. After 30 min of CPR both manual and mechanical CPR groups were resuscitated following a standardized ALS protocol. During CPR, coronary perfusion pressure and end tidal CO2 were greater with mechanical CPR. All animals were successfully resuscitated and neurological deficit scores were not different. The CPR trauma score was less in the mechanical group. Mechanical external chest compression provided better haemodynamics than the manual technique, though outcome did not differ. Both optimally performed manual and mechanical techniques produce flow sufficient to maintain organ viability for 30 min of CPR after a 1 min arrest interval.

  7. Mechanical chest compression with a medical parallel manipulator for cardiopulmonary resuscitation.

    PubMed

    Yedukondalu, G; Srinath, A; Suresh Kumar, J

    2015-12-01

    Chest compression is the primary technique in emergency situations for resuscitating patients who have a cardiac arrest. Even for experienced personnel, it is difficult to perform chest compressions at the correct compression rate and depth. We describe a new translational three-revolute-revolute-revolute (3-RRR) parallel manipulator designed for delivering chest compressions. The kinematic and chest analyses have been carried out analytically. The motion of the parallel manipulator while performing chest compressions was simulated under experimental conditions and the results were verified in MSC ADAMS software. Simulation and experimental results had more or less similar results. The proposed parallel manipulator was able to achieve 120 compressions/min (cpm) with a depth in the range 38-51 mm during cardio-pulmonary resuscitation (CPR). The design of the manipulator makes it easy to deploy for performing chest compressions at the correct compression rate and depth, as outlined in the 2010 resuscitation guidelines. Copyright © 2014 John Wiley & Sons, Ltd.

  8. Advanced life support performance with manual and mechanical chest compressions in a randomized, multicentre manikin study.

    PubMed

    Tomte, Oystein; Sunde, Kjetil; Lorem, Tonje; Auestad, Bjorn; Souders, Chris; Jensen, Jeff; Wik, Lars

    2009-10-01

    Clinical mechanical chest compression studies report diverging outcomes. Confounding effects of variability in hands-off fraction (HOF) and timing of necessary tasks during advanced life support (ALS) may contribute to this divergence. Study site variability in these factors coupled to randomization of cardiopulmonary resuscitation (CPR) method was studied during simulated cardiac arrest prior to a multicentre clinical trial. Ambulance personnel from four sites were tested in randomized, simulated cardiac arrest scenarios with manual CPR or load-distributing band CPR (LDB-CPR) on manikins. Primary emphasis was on HOF and time spent before necessary predefined ALS task (ALS milestones). Results are presented as mean differences (confidence interval). At the site with lowest HOF during manual CPR, HOF deteriorated with LDB-CPR by 0.06 (0.005, 0.118, p=0.04), while it improved at the two sites with highest HOF during manual CPR by 0.07 (0.019, 0.112, p=0.007) and 0.08 (0.004, 0.165, p=0.042). Initial defibrillation was 29 (3, 55, p=0.032)s delayed for LDB-CPR vs. manual CPR. Other ALS milestones trended toward earlier completion with LDB-CPR; only significant for intravenous access, mean difference 70 (24, 115, p=0.003)s. In this manikin study, HOF for manual vs. mechanical chest compressions varied between sites. Study protocol implementation should be simulation tested before launching multicentre trials, to optimize performance and improve reliability and scientific interpretation.

  9. Mechanical chest compressions in an avalanche victim with cardiac arrest: an option for extreme mountain rescue operations.

    PubMed

    Pietsch, Urs; Lischke, Volker; Pietsch, Christine; Kopp, Karl-Heinz

    2014-06-01

    Mountain rescue operations often present helicopter emergency medical service crews with unique challenges. One of the most challenging problems is the prehospital care of cardiac arrest patients during evacuation and transport. In this paper we outline a case in which we successfully performed a cardiopulmonary resuscitation of an avalanche victim. A mechanical chest-compression device proved to be a good way of minimizing hands-off time and providing high-quality chest compressions while the patient was evacuated from the site of the accident.

  10. External chest compressions using a mechanical feedback device : cross-over simulation study.

    PubMed

    Skorning, M; Derwall, M; Brokmann, J C; Rörtgen, D; Bergrath, S; Pflipsen, J; Beuerlein, S; Rossaint, R; Beckers, S K

    2011-08-01

    External chest compressions (ECC) are essential components of resuscitation and are usually performed without any adjuncts in professional healthcare. Even for healthcare professionals during in-hospital and out-of-hospital resuscitation poor performance in ECC has been reported in recent years. Although several stand-alone devices have been developed none has been implemented as a standard in patient care. The aim of this study was to examine if the use of a mechanical device providing visual feedback and audible assistance during ECC improves performance of healthcare professionals following minimal and simplified instructions. In a prospective, randomized cross-over study 81 healthcare professionals performed ECC for 3 min (in the assumed setting of a secured airway) twice on a manikin (Skillreporter ResusciAnne®, with PC-Skillreporting System Version 1.3.0, Laerdal, Stavanger, Norway) in a mock cardiac arrest scenario. Group 1 (n=40) performed ECC with the device first followed by classic ECC and group 2 (n=41) in the opposite order. Minimal instructions were standardized and provided by video instruction (1 min 38 s). Endpoints were achievement of a mean compression rate between 90 and 110/min and a mean compression depth of 40-50 mm. In addition participants had to answer questionnaires about demographic data, professional experience and recent recommendations for ECC as well as their impression of the device concerning the ease of use and their personal level of confidence. Data were analyzed for group-related and inter-group differences using SAS (Version 9.1.3, SAS Institute, Cary, NC). A total of 81 healthcare professionals regularly involved in resuscitation attempts in pre-hospital or in-hospital settings took part in the study with no differences between the groups: females 35.8% (n=52), emergency medical technicians 32.1% (n=26), anesthesia nurses 32.1% (n=26), physicians (anesthesiology) 45% (n=29). In group 1 33 out of 40 (82.5%; 99.7±4

  11. Device Assists Cardiac Chest Compression

    NASA Technical Reports Server (NTRS)

    Eichstadt, Frank T.

    1995-01-01

    Portable device facilitates effective and prolonged cardiac resuscitation by chest compression. Developed originally for use in absence of gravitation, also useful in terrestrial environments and situations (confined spaces, water rescue, medical transport) not conducive to standard manual cardiopulmonary resuscitation (CPR) techniques.

  12. Device Assists Cardiac Chest Compression

    NASA Technical Reports Server (NTRS)

    Eichstadt, Frank T.

    1995-01-01

    Portable device facilitates effective and prolonged cardiac resuscitation by chest compression. Developed originally for use in absence of gravitation, also useful in terrestrial environments and situations (confined spaces, water rescue, medical transport) not conducive to standard manual cardiopulmonary resuscitation (CPR) techniques.

  13. Filtering mechanical chest compression artefacts from out-of-hospital cardiac arrest data.

    PubMed

    Aramendi, E; Irusta, U; Ayala, U; Naas, H; Kramer-Johansen, J; Eftestøl, T

    2016-01-01

    Filtering techniques to remove manual compression artefacts from the ECG have not been incorporated to defibrillators to diagnose the rhythm during cardiopulmonary resuscitation. Mechanical and manual compression artefacts may be very different. The aim of this study is to characterize the compression artefact caused by the LUCAS 2 device and to evaluate whether filtering the LUCAS 2 artefact results in an accurate rhythm analysis. A dataset of 1045 segments were obtained from 230 out-of-hospital cardiac arrest (OHCA) patients after LUCAS 2 activation. Rhythms were 201 shockable, 270 asystole and 574 organized. Segments during asystole were used to characterize the artefact in time and frequency domains. Three filtering methods, a comb filter and two adaptive filters, were used to remove the mechanical compression artefact. The filtered ECG was then diagnosed with a shock decision algorithm from a defibrillator. When compared to the manual compression artefact, the LUCAS 2 artefact presented a similar amplitude (1.2 mV, p-value 0.26), fixed frequency (101.7 min(-1)), more harmonic components, smaller spectral dispersion, and a more regular waveform (p-val <3 × 10(-7)). The sensitivity (SE) and specificity (SP) before filtering the LUCAS 2 artefact were 52.8% (90% low CI, 46.0%) and 81.5% (79.0%), respectively. For the best filter, SE and SP after filtering were 97.9% (95.7%) and 84.1% (82.0%), respectively. Optimal filters require more harmonics and smaller bandwidths than for manual compressions. Filtering resulted in a large increase in SE and small increase in SP. Despite differences in artefact characteristics between manual and mechanical compressions, filtering the LUCAS 2 compression artefact results in SE/SP values comparable to those obtained for manual compression artefacts. The SP is still below the 95% recommended by the American Heart Association. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  14. Correlations between quality indexes of chest compression

    PubMed Central

    Zhang, Feng-ling; Yan, Li; Huang, Su-fang; Bai, Xiang-jun

    2013-01-01

    BACKGROUND: Cardiopulmonary resuscitation (CPR) is a kind of emergency treatment for cardiopulmonary arrest, and chest compression is the most important and necessary part of CPR. The American Heart Association published the new Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care in 2010 and demanded for better performance of chest compression practice, especially in compression depth and rate. The current study was to explore the relationship of quality indexes of chest compression and to identify the key points in chest compression training and practice. METHODS: Totally 219 healthcare workers accepted chest compression training by using Laerdal ACLS advanced life support resuscitation model. The quality indexes of chest compression, including compression hands placement, compression rate, compression depth, and chest wall recoil as well as self-reported fatigue time were monitored by the Laerdal Computer Skills and Reporting System. RESULTS: The quality of chest compression was related to the gender of the compressor. The indexes in males, including self-reported fatigue time, the accuracy of compression depth and the compression rate, the accuracy of compression rate, were higher than those in females. However, the accuracy of chest recoil was higher in females than in males. The quality indexes of chest compression were correlated with each other. The self-reported fatigue time was related to all the indexes except the compression rate. CONCLUSION: It is necessary to offer CPR training courses regularly. In clinical practice, it might be better to change the practitioner before fatigue, especially for females or weak practitioners. In training projects, more attention should be paid to the control of compression rate, in order to delay the fatigue, guarantee enough compression depth and improve the quality of chest compression. PMID:25215093

  15. A simulation tool to study high-frequency chest compression energy transfer mechanisms and waveforms for pulmonary disease applications.

    PubMed

    O'Clock, George D; Lee, Yong Wan; Lee, Jongwon; Warwick, Warren J

    2010-07-01

    High-frequency chest compression (HFCC) can be used as a therapeutic intervention to assist in the transport and clearance of mucus and enhance water secretion for cystic fibrosis patients. An HFCC pump-vest and half chest-lung simulation, with 23 lung generations, has been developed using inertance, compliance, viscous friction relationships, and Newton's second law. The simulation has proven to be useful in studying the effects of parameter variations and nonlinear effects on HFCC system performance and pulmonary system response. The simulation also reveals HFCC waveform structure and intensity changes in various segments of the pulmonary system. The HFCC system simulation results agree with measurements, indicating that the HFCC energy transport mechanism involves a mechanically induced pulsation or vibration waveform with average velocities in the lung that are dependent upon small air displacements over large areas associated with the vest-chest interface. In combination with information from lung physiology, autopsies and a variety of other lung modeling efforts, the results of the simulation can reveal a number of therapeutic implications.

  16. Chest compression with a higher level of pressure support ventilation: effects on secretion removal, hemodynamics, and respiratory mechanics in patients on mechanical ventilation.

    PubMed

    Naue, Wagner da Silva; Forgiarini Junior, Luiz Alberto; Dias, Alexandre Simões; Vieira, Silvia Regina Rios

    2014-01-01

    To determine the efficacy of chest compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation, in comparison with that of aspiration alone, in removing secretions, normalizing hemodynamics, and improving respiratory mechanics in patients on mechanical ventilation. This was a randomized crossover clinical trial involving patients on mechanical ventilation for more than 48 h in the ICU of the Porto Alegre Hospital de Clínicas, in the city of Porto Alegre, Brazil. Patients were randomized to receive aspiration alone (control group) or compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation (intervention group). We measured hemodynamic parameters, respiratory mechanics parameters, and the amount of secretions collected. We included 34 patients. The mean age was 64.2 ± 14.6 years. In comparison with the control group, the intervention group showed a higher median amount of secretions collected (1.9 g vs. 2.3 g; p = 0.004), a greater increase in mean expiratory tidal volume (16 ± 69 mL vs. 56 ± 69 mL; p = 0.018), and a greater increase in mean dynamic compliance (0.1 ± 4.9 cmH2O vs. 2.8 ± 4.5 cmH2O; p = 0.005). In this sample, chest compression accompanied by an increase in pressure support significantly increased the amount of secretions removed, the expiratory tidal volume, and dynamic compliance. (ClinicalTrials.gov Identifier:NCT01155648 [http://www.clinicaltrials.gov/]).

  17. Chest compression with a higher level of pressure support ventilation: effects on secretion removal, hemodynamics, and respiratory mechanics in patients on mechanical ventilation*

    PubMed Central

    Naue, Wagner da Silva; Forgiarini, Luiz Alberto; Dias, Alexandre Simões; Vieira, Silvia Regina Rios

    2014-01-01

    OBJECTIVE: To determine the efficacy of chest compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation, in comparison with that of aspiration alone, in removing secretions, normalizing hemodynamics, and improving respiratory mechanics in patients on mechanical ventilation. METHODS: This was a randomized crossover clinical trial involving patients on mechanical ventilation for more than 48 h in the ICU of the Porto Alegre Hospital de Clínicas, in the city of Porto Alegre, Brazil. Patients were randomized to receive aspiration alone (control group) or compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation (intervention group). We measured hemodynamic parameters, respiratory mechanics parameters, and the amount of secretions collected. RESULTS: We included 34 patients. The mean age was 64.2 ± 14.6 years. In comparison with the control group, the intervention group showed a higher median amount of secretions collected (1.9 g vs. 2.3 g; p = 0.004), a greater increase in mean expiratory tidal volume (16 ± 69 mL vs. 56 ± 69 mL; p = 0.018), and a greater increase in mean dynamic compliance (0.1 ± 4.9 cmH2O vs. 2.8 ± 4.5 cmH2O; p = 0.005). CONCLUSIONS: In this sample, chest compression accompanied by an increase in pressure support significantly increased the amount of secretions removed, the expiratory tidal volume, and dynamic compliance. (ClinicalTrials.gov Identifier:NCT01155648 [http://www.clinicaltrials.gov/]) PMID:24626270

  18. A quality improvement initiative to optimize use of a mechanical chest compression device within a high-performance CPR approach to out-of-hospital cardiac arrest resuscitation.

    PubMed

    Levy, Michael; Yost, Dana; Walker, Robert G; Scheunemann, Erich; Mendive, Steve R

    2015-07-01

    Minimizing the chest compression pause associated with application of a mechanical CPR device is a key component of optimal integration into the overall resuscitation process. As part of a multi-agency implementation project, Anchorage Fire Department deployed LUCAS CPR devices on BLS and ALS fire apparatus for initiation early in resuscitation efforts. A 2012 report identified the pause interval for device application as a key opportunity for quality improvement (QI). In early 2013 we began a QI initiative to reduce device application time interval and optimize the overall CPR process. To assess QI initiative effectiveness, we compared key CPR process metrics from before to during and after its implementation. We included all cases of EMS-treated out-of-hospital cardiac arrest during 2012 and 2013 in which a mechanical CPR device was used and the defibrillator electronic record was available. Continuous ECG and impedance data were analyzed to measure chest compression fraction, duration of the pause from last manual to first mechanical compression, and duration of the longest overall pause in the resuscitation effort. Compared to cases from 2012 (n = 61), median duration of the pause prior to first mechanical compression for cases from 2013 (n = 71) decreased from 21 (15, 31) to 7 (4, 12)s (p < 0.001), while median chest compression fraction increased from 0.90 (0.88, 0.93) to 0.95 (0.93, 0.96) (p < 0.001). Median duration of the longest pause decreased from 25 (20, 35) to 13 (10, 20)s (p < 0.001), while the proportion of cases where the longest pause was for mechanical CPR application decreased from 74% to 31% (p < 0.001). Our QI initiative substantially reduced the duration of the pause prior to first mechanical compression. Combined with the simultaneous significant increase in compression fraction and significant decrease in duration of the longest pause, this finding strongly suggests a large improvement in mechanical CPR device application efficiency within

  19. Pre-shock chest compression pause effects on termination of ventricular fibrillation/tachycardia and return of organized rhythm within mechanical and manual cardiopulmonary resuscitation.

    PubMed

    Olsen, Jan-Aage; Brunborg, Cathrine; Steinberg, Mikkel; Persse, David; Sterz, Fritz; Lozano, Michael; Westfall, Mark; Travis, David T; Lerner, E Brooke; Brouwer, Marc A; Wik, Lars

    2015-08-01

    Shorter manual chest compression pauses prior to defibrillation attempts is reported to improve the defibrillation success rate. Mechanical load-distributing band (LDB-) CPR enables shocks without compression pause. We studied pre-shock pause and termination of ventricular fibrillation/pulseless ventricular tachycardia 5s post-shock (TOF) and return of organized rhythm (ROOR) with LDB and manual (M-) CPR. In a secondary analysis from the Circulation Improving Resuscitation Care trial, patients with initial shockable rhythm and interpretable post-shock rhythms were included. Pre-shock rhythm, pause duration (if any), and post-shock rhythm were obtained for each shock. Associations between TOF/ROOR and pre-shock pause duration, including no pause shocks with LDB-CPR, were analyzed with Chi-square test. A p-value <0.05 was considered statistically significant. For TOF and ROOR analyses we included 417 LDB-CPR patients with 1476 and 1438 shocks, and 495 M-CPR patients with 1839 and 1796 shocks, respectively. For first shocks with LDB-CPR, pre-shock pause was associated with TOF (p=0.049) with lowest TOF (77%) for shocks given without pre-shock compression pause. This association was not significant when all shocks were included (p=0.07) and not for ROOR. With M-CPR there were no significant associations between shock-related chest compression pause duration and TOF or ROOR. For first shocks with LDB-CPR, termination of fibrillation was associated with pre-shock pause duration. There was no association for the rate of return of organized rhythm. For M-CPR, where no shocks were given during continuous chest compressions, there were no associations between pre-shock pause duration and TOF or ROOR. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  20. Effect of the rate of chest compression familiarised in previous training on the depth of chest compression during metronome-guided cardiopulmonary resuscitation: a randomised crossover trial

    PubMed Central

    Bae, Jinkun; Chung, Tae Nyoung; Je, Sang Mo

    2016-01-01

    Objectives To assess how the quality of metronome-guided cardiopulmonary resuscitation (CPR) was affected by the chest compression rate familiarised by training before the performance and to determine a possible mechanism for any effect shown. Design Prospective crossover trial of a simulated, one-person, chest-compression-only CPR. Setting Participants were recruited from a medical school and two paramedic schools of South Korea. Participants 42 senior students of a medical school and two paramedic schools were enrolled but five dropped out due to physical restraints. Intervention Senior medical and paramedic students performed 1 min of metronome-guided CPR with chest compressions only at a speed of 120 compressions/min after training for chest compression with three different rates (100, 120 and 140 compressions/min). Friedman's test was used to compare average compression depths based on the different rates used during training. Results Average compression depths were significantly different according to the rate used in training (p<0.001). A post hoc analysis showed that average compression depths were significantly different between trials after training at a speed of 100 compressions/min and those at speeds of 120 and 140 compressions/min (both p<0.001). Conclusions The depth of chest compression during metronome-guided CPR is affected by the relative difference between the rate of metronome guidance and the chest compression rate practised in previous training. PMID:26873050

  1. Chest compression rate measurement from smartphone video.

    PubMed

    Engan, Kjersti; Hinna, Thomas; Ryen, Tom; Birkenes, Tonje S; Myklebust, Helge

    2016-08-11

    Out-of-hospital cardiac arrest is a life threatening situation where the first person performing cardiopulmonary resuscitation (CPR) most often is a bystander without medical training. Some existing smartphone apps can call the emergency number and provide for example global positioning system (GPS) location like Hjelp 113-GPS App by the Norwegian air ambulance. We propose to extend functionality of such apps by using the built in camera in a smartphone to capture video of the CPR performed, primarily to estimate the duration and rate of the chest compression executed, if any. All calculations are done in real time, and both the caller and the dispatcher will receive the compression rate feedback when detected. The proposed algorithm is based on finding a dynamic region of interest in the video frames, and thereafter evaluating the power spectral density by computing the fast fourier transform over sliding windows. The power of the dominating frequencies is compared to the power of the frequency area of interest. The system is tested on different persons, male and female, in different scenarios addressing target compression rates, background disturbances, compression with mouth-to-mouth ventilation, various background illuminations and phone placements. All tests were done on a recording Laerdal manikin, providing true compression rates for comparison. Overall, the algorithm is seen to be promising, and it manages a number of disturbances and light situations. For target rates at 110 cpm, as recommended during CPR, the mean error in compression rate (Standard dev. over tests in parentheses) is 3.6 (0.8) for short hair bystanders, and 8.7 (6.0) including medium and long haired bystanders. The presented method shows that it is feasible to detect the compression rate of chest compressions performed by a bystander by placing the smartphone close to the patient, and using the built-in camera combined with a video processing algorithm performed real-time on the device.

  2. Mechanical chest compression does not seem to improve outcome after out-of hospital cardiac arrest. A single center observational trial.

    PubMed

    Zeiner, Sebastian; Sulzgruber, Patrick; Datler, Philip; Keferböck, Markus; Poppe, Michael; Lobmeyr, Elisabeth; van Tulder, Raphael; Zajicek, Andreas; Buchinger, Angelika; Polz, Karl; Schrattenbacher, Georg; Sterz, Fritz

    2015-11-01

    Recently three large post product placement studies, comparing mechanical chest compression (cc) devices to those who received manual cc, found equivalent outcome results for both groups. Thus the question arises whether those results could be replicated using the devices on a daily routine. We prospectively enrolled 948 patients over a 12 months period. Chi-Square test and Mann-Whitney-U test were used to assess differences between "manual" and "mechanical" cc subgroups. Uni- and multivariate Cox regression hazard analysis were used to assess the influence of cc type on survival. A mechanical cc device was used in 30.1% (n=283) cases. Patients who received mechanical cc had a significantly worse neurological outcome - measured in cerebral performance category (CPC) - than the manual cc group (56.8% vs. 78.6%, p=0.009). Patients receiving mechanical cc were significantly younger, more were male and were more likely to have bystander CPR and an initially shock-able ECG rhythm. There was no difference in the quality of CPR that might explain the worse outcome in mechanical cc patients. Even with high quality CPR in both, manual and mechanical cc groups, outcome in patients who received mechanical cc was significantly worse. The anticipated benefits of a higher compression ratio and a steadier compression depth of a mechanical cc device remain uncertain. In this study selection for mechanical cc was not standardized, and was non-random. This merits further investigation. Further research on how mechanical cc is chosen and used should be considered. https://ekmeduniwien.at/core/catalog/2013/ (EK-Nr:1221/2013). Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  3. Quality of chest compressions during continuous CPR; comparison between chest compression-only CPR and conventional CPR.

    PubMed

    Nishiyama, Chika; Iwami, Taku; Kawamura, Takashi; Ando, Masahiko; Yonemoto, Naohiro; Hiraide, Atsushi; Nonogi, Hiroshi

    2010-09-01

    This study aimed to compare the time-dependent deterioration of chest compressions between chest compression-only cardiopulmonary resuscitation (CPR) and conventional CPR. This study involved 106 and 107 participants randomly assigned to chest compression-only CPR training and conventional CPR training, respectively. Immediately after training, participants were asked to perform CPR for 2 min and the quality of their CPR skills were evaluated. The number of chest compressions in total and those with appropriate depth were counted every 20-s CPR period from the start of CPR. The primary outcome was the CPR quality index calculated as the proportion of chest compressions with appropriate depth among total chest compressions. The total number of chest compressions remained stable over time both in the chest compression-only and the conventional CPR groups. The CPR quality index, however, decreased from 86.6+/-25.0 to 58.2+/-36.9 in the chest compression-only CPR group from 0-20 s through 61-80 s. The reduction was greater than in the conventional CPR group (85.9+/-25.5 to 74.3+/-34.0). The difference in the CPR quality index reached statistical significance (p=0.003) at 61-80 s period. Chest compressions with appropriate depth decreased more rapidly during chest compression-only CPR than conventional CPR. We recommend that CPR providers change their roles every 1 min to maintain the quality of chest compressions during chest compression-only CPR. (UMIN-CTR C0000000321). Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

  4. Comparison of chest compression quality between the modified chest compression method with the use of smartphone application and the standardized traditional chest compression method during CPR.

    PubMed

    Park, Sang-Sub

    2014-01-01

    The purpose of this study is to grasp difference in quality of chest compression accuracy between the modified chest compression method with the use of smartphone application and the standardized traditional chest compression method. Participants were progressed 64 people except 6 absentees among 70 people who agreed to participation with completing the CPR curriculum. In the classification of group in participants, the modified chest compression method was called as smartphone group (33 people). The standardized chest compression method was called as traditional group (31 people). The common equipments in both groups were used Manikin for practice and Manikin for evaluation. In the meantime, the smartphone group for application was utilized Android and iOS Operating System (OS) of 2 smartphone products (G, i). The measurement period was conducted from September 25th to 26th, 2012. Data analysis was used SPSS WIN 12.0 program. As a result of research, the proper compression depth (mm) was shown the proper compression depth (p< 0.01) in traditional group (53.77 mm) compared to smartphone group (48.35 mm). Even the proper chest compression (%) was formed suitably (p< 0.05) in traditional group (73.96%) more than smartphone group (60.51%). As for the awareness of chest compression accuracy, the traditional group (3.83 points) had the higher awareness of chest compression accuracy (p< 0.001) than the smartphone group (2.32 points). In the questionnaire that was additionally carried out 1 question only in smartphone group, the modified chest compression method with the use of smartphone had the high negative reason in rescuer for occurrence of hand back pain (48.5%) and unstable posture (21.2%).

  5. New cardiopulmonary resuscitation guidelines 2005: importance of uninterrupted chest compression.

    PubMed

    Ristagno, Giuseppe; Gullo, Antonino; Tang, Wanchun; Weil, Max Harry

    2006-07-01

    The evidence supports quality controlled chest compression as the initial intervention after "sudden death" before attempted defibrillation, if the duration of cardiac arrest is more than 5 minutes. The new guidelines mandate lesser interruptions for ventilation, before and following electrical shocks, and single rather than multiple electrical shocks before resuming chest compression. The new guidelines refocus on uninterrupted chest compression after cardiac arrest of nonasphyxial cause and modifications in practices that reduce the need for interruptions.

  6. Chest Compression Fraction between Mechanical Compressions on a Reducible Stretcher and Manual Compressions on a Standard Stretcher during Transport in Out-of-Hospital Cardiac Arrests: The Ambulance Stretcher Innovation of Asian Cardiopulmonary Resuscitation (ASIA-CPR) Pilot Trial.

    PubMed

    Kim, Tae Han; Shin, Sang Do; Song, Kyoung Jun; Hong, Ki Jeong; Ro, Young Sun; Song, Sung Wook; Kim, Chu Hyun

    2017-01-01

    Cardiopulmonary resuscitation (CPR) with the use of mechanical devices is recommended during ambulance transport. However, the CPR quality en route and while in transfer to the emergency department (ED) for out-of-hospital cardiac arrests (OHCAs) remains uncertain. We developed a mechanical CPR device outfitted on a reducible stretcher (M-CPR) and compared with standard manual CPR on a standard stretcher (S-CPR) to evaluate CPR quality. Adult OHCAs transported by five ambulances in a metropolitan area with a population of 3.5 million (many of whom lived in high-rise buildings) from September to October (before-phase) and November to December (after-phase) in 2015 were collected. The reducible stretcher was developed for use in a small elevator during the transfer from scene to ambulance, and the AutoPulse® (ZOLL Medical, Chelmsford, MA, USA) was used for M-CPR. Chest compression fraction (CCF) was measured by transthoracic impedance data using an X-series® cardiac monitor (ZOLL Medical) during time from attachment to patient to arrival to the ED. A comparison of CCF using a Wilcoxon signed-rank test evaluated the difference between the before- and after-phases. Of the eligible 49 OHCAs, 31 (21 in the before-phase and 10 in the after-phase) were analyzed, excluding patients for whom CCF was not measured, for whom M-CPR was not used, who had a return of spontaneous circulation in the field before transport, or who collapsed during transport. There were no differences in demographic data. Median total CCF (median, q1-q3) was significantly higher in the after-phase M-CPR group (85.2, 83.4-86.3) than in the before-phase S-CPR group (80.1, 68.0-85.2) (p = 0.03). Mechanical CPR on the reducible stretcher during the transport of OHCAs to the ED showed a much higher chest compression fraction than standard manual CPR.

  7. An optimal closed-loop control strategy for mechanical chest compression devices: a trade-off between the risk of chest injury and the benefit of enhanced blood flow.

    PubMed

    Zhang, Guang; Zheng, Jie-Wen; Wu, Jian; Wu, Tai-Hu

    2012-10-01

    The widespread application of chest compression (CC) as a first aid measure inevitably has the potential for both harm and benefit. The present study was therefore undertaken to design an optimal CC closed-loop control strategy (OCCCS) for mechanical CC devices that will present an effective trade-off between the risk of chest injury and the benefit of blood flow during CPR. Additionally, to evaluate the CC performance of the OCCCS, the differences between the OCCCS and the traditional mechanical CC method (TMCM) of performing standard CC were explored. Using the computer simulation technique, partial pressure of end-tidal CO₂ (PETCO2) and human chest stiffness are simulated based on the Babbs' model in present study. PETCO2 was regarded as a benefit factor (BF), which was divided into 3 levels, while chest stiffness was regarded as a risk factor (RF), which was divided into 4 levels. A benefit versus risk index (BRI) was also constructed for the comprehensive evaluation of risk and benefit. An OCCCS was developed with the combination of the BF, RF, BRI and fuzzy control strategy. A comparison between the OCCCS and TMCM was then performed based on computer simulations. The OCCCS obtained a greater BRI and a better trade-off between risk and benefit than the TMCM in 6 out of a total 9 cases, and the OCCCS also resulted in a significantly improved cardiac output (CO) and PETCO2 in 6 of the 9 cases. The mean BRI, CO and PETCO2 resulting from the OCCCS were 5.69, 1.45 L/min and 15.51 mmHg, respectively, while the mean BRI, CO and PETCO2 resulting from TMCM were 4.76, 1.18 L/min and 13.26 mmHg, respectively. The OCCCS can provide safer and more effective CC during cardiopulmonary resuscitation (CPR) compared to the TMCM, and has great potential in the future mechanical CC device development. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  8. Feasibility of Biosignal-guided Chest Compression During Cardiopulmonary Resuscitation: A Proof of Concept.

    PubMed

    Sundermann, Matthew L; Salcido, David D; Koller, Allison C; Menegazzi, James J

    2016-01-01

    Cardiac arrest is one of the leading causes of death in the United States and is treated by cardiopulmonary resuscitation (CPR). CPR involves both chest compressions and positive pressure ventilations when given by medical providers. Mechanical chest compression devices automate chest compressions and are beginning to be adopted by emergency medical services with the intent of providing high-quality, consistent chest compressions that are not limited by human providers who can become fatigued. Biosignals acquired from cardiac arrest patients have been characterized in their ability to track the effect of CPR on the patient. The authors investigated the feasibility and appropriate response of a biosignal-guided mechanical chest compression device in a swine model of cardiac arrest. After a custom signal-guided chest compression device was engineered, its ability to respond to biosignal changes in a swine model of cardiac arrest was tested. In a preliminary series of six swine, two biosignals were used: mean arterial pressure (MAP) and a mathematical derivative of the electrocardiogram waveform, median slope (MS). How these biosignals changed was observed when chest compression rate and depth were adjusted by the signal-guided chest compression device, independent of the user. Chest compression rate and depth were adjusted by the signal-guided chest compression device according to a preset threshold algorithm until either of the biosignals improved to satisfy a set "threshold" or until the chest compression rate and depth achieved maximum values. Defibrillation was attempted at the end of each resuscitation in an effort to achieve return of spontaneous circulation (ROSC). The signal-guided chest compression device responded appropriately to biosignals by changing its rate and depth. All animals exhibited positive improvements in their biosignals. During the course of the resuscitation, three of the six animals improved their MS biosignal to reach the MS threshold

  9. Effect of the rate of chest compression familiarised in previous training on the depth of chest compression during metronome-guided cardiopulmonary resuscitation: a randomised crossover trial.

    PubMed

    Bae, Jinkun; Chung, Tae Nyoung; Je, Sang Mo

    2016-02-12

    To assess how the quality of metronome-guided cardiopulmonary resuscitation (CPR) was affected by the chest compression rate familiarised by training before the performance and to determine a possible mechanism for any effect shown. Prospective crossover trial of a simulated, one-person, chest-compression-only CPR. Participants were recruited from a medical school and two paramedic schools of South Korea. 42 senior students of a medical school and two paramedic schools were enrolled but five dropped out due to physical restraints. Senior medical and paramedic students performed 1 min of metronome-guided CPR with chest compressions only at a speed of 120 compressions/min after training for chest compression with three different rates (100, 120 and 140 compressions/min). Friedman's test was used to compare average compression depths based on the different rates used during training. Average compression depths were significantly different according to the rate used in training (p<0.001). A post hoc analysis showed that average compression depths were significantly different between trials after training at a speed of 100 compressions/min and those at speeds of 120 and 140 compressions/min (both p<0.001). The depth of chest compression during metronome-guided CPR is affected by the relative difference between the rate of metronome guidance and the chest compression rate practised in previous training. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  10. Factors influencing quality of chest compression depth in nursing students.

    PubMed

    Roh, Young Sook; Lim, Eun Ju

    2013-12-01

    The purpose of the study was to identify factors influencing quality of chest compression depth in nursing students. A convenience sample of 102 female nursing students enrolled in a cardiopulmonary resuscitation skills training session. Each student performed 3 min of chest compression skills on a Resusci Anne SkillReporter manikin for measurements of both depth and rate. Nursing students with correct compression depth (50-60 mm) had higher body weight (t = -2.02, P = 0.046) and body mass index (t = -2.19, P = 0.031) compared with students in the incorrect depth group. Mean chest compression depth was shallower in underweight nursing students compared with normal weight or overweight students (F = 8.89, P < 0.001). Body weight was a significant factor influencing quality of chest compression depth (F = 4.25, P = 0.003). Educational intervention targeting underweight nursing students might need to enhance the quality of chest compression skills.

  11. Continuous chest compression versus interrupted chest compression for cardiopulmonary resuscitation of non-asphyxial out-of-hospital cardiac arrest.

    PubMed

    Zhan, Lei; Yang, Li J; Huang, Yu; He, Qing; Liu, Guan J

    2017-03-27

    Out-of-hospital cardiac arrest (OHCA) is a major cause of death worldwide. Cardiac arrest can be subdivided into asphyxial and non asphyxial etiologies. An asphyxia arrest is caused by lack of oxygen in the blood and occurs in drowning and choking victims and in other circumstances. A non asphyxial arrest is usually a loss of functioning cardiac electrical activity. Cardiopulmonary resuscitation (CPR) is a well-established treatment for cardiac arrest. Conventional CPR includes both chest compressions and 'rescue breathing' such as mouth-to-mouth breathing. Rescue breathing is delivered between chest compressions using a fixed ratio, such as two breaths to 30 compressions or can be delivered asynchronously without interrupting chest compression. Studies show that applying continuous chest compressions is critical for survival and interrupting them for rescue breathing might increase risk of death. Continuous chest compression CPR may be performed with or without rescue breathing. To assess the effects of continuous chest compression CPR (with or without rescue breathing) versus conventional CPR plus rescue breathing (interrupted chest compression with pauses for breaths) of non-asphyxial OHCA. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 1 2017); MEDLINE (Ovid) (from 1985 to February 2017); Embase (1985 to February 2017); Web of Science (1985 to February 2017). We searched ongoing trials databases including controlledtrials.com and clinicaltrials.gov. We did not impose any language or publication restrictions. We included randomized and quasi-randomized studies in adults and children suffering non-asphyxial OHCA due to any cause. Studies compared the effects of continuous chest compression CPR (with or without rescue breathing) with interrupted CPR plus rescue breathing provided by rescuers (bystanders or professional CPR providers). Two authors extracted the data and summarized the effects as risk ratios (RRs), adjusted risk

  12. Football Equipment Removal Improves Chest Compression and Ventilation Efficacy.

    PubMed

    Mihalik, Jason P; Lynall, Robert C; Fraser, Melissa A; Decoster, Laura C; De Maio, Valerie J; Patel, Amar P; Swartz, Erik E

    2016-01-01

    Airway access recommendations in potential catastrophic spine injury scenarios advocate for facemask removal, while keeping the helmet and shoulder pads in place for ensuing emergency transport. The anecdotal evidence to support these recommendations assumes that maintaining the helmet and shoulder pads assists inline cervical stabilization and that facial access guarantees adequate airway access. Our objective was to determine the effect of football equipment interference on performing chest compressions and delivering adequate ventilations on patient simulators. We hypothesized that conditions with more football equipment would decrease chest compression and ventilation efficacy. Thirty-two certified athletic trainers were block randomized to participate in six different compression conditions and six different ventilation conditions using human patient simulators. Data for chest compression (mean compression depth, compression rate, percentage of correctly released compressions, and percentage of adequate compressions) and ventilation (total ventilations, mean ventilation volume, and percentage of ventilations delivering adequate volume) conditions were analyzed across all conditions. The fully equipped athlete resulted in the lowest mean compression depth (F5,154 = 22.82; P < 0.001; Effect Size = 0.98) and delivery of adequate compressions (F5,154 = 15.06; P < 0.001; Effect Size = 1.09) compared to all other conditions. Bag-valve mask conditions resulted in delivery of significantly higher mean ventilation volumes compared to all 1- or 2-person pocketmask conditions (F5,150 = 40.05; P < 0.001; Effect Size = 1.47). Two-responder ventilation scenarios resulted in delivery of a greater number of total ventilations (F5,153 = 3.99; P = 0.002; Effect Size = 0.26) and percentage of adequate ventilations (F5,150 = 5.44; P < 0.001; Effect Size = 0.89) compared to one-responder scenarios. Non-chinstrap conditions permitted greater ventilation volumes (F3,28 = 35.17; P

  13. Trial of Continuous or Interrupted Chest Compressions during CPR.

    PubMed

    Nichol, Graham; Leroux, Brian; Wang, Henry; Callaway, Clifton W; Sopko, George; Weisfeldt, Myron; Stiell, Ian; Morrison, Laurie J; Aufderheide, Tom P; Cheskes, Sheldon; Christenson, Jim; Kudenchuk, Peter; Vaillancourt, Christian; Rea, Thomas D; Idris, Ahamed H; Colella, Riccardo; Isaacs, Marshal; Straight, Ron; Stephens, Shannon; Richardson, Joe; Condle, Joe; Schmicker, Robert H; Egan, Debra; May, Susanne; Ornato, Joseph P

    2015-12-03

    During cardiopulmonary resuscitation (CPR) in patients with out-of-hospital cardiac arrest, the interruption of manual chest compressions for rescue breathing reduces blood flow and possibly survival. We assessed whether outcomes after continuous compressions with positive-pressure ventilation differed from those after compressions that were interrupted for ventilations at a ratio of 30 compressions to two ventilations. This cluster-randomized trial with crossover included 114 emergency medical service (EMS) agencies. Adults with non-trauma-related cardiac arrest who were treated by EMS providers received continuous chest compressions (intervention group) or interrupted chest compressions (control group). The primary outcome was the rate of survival to hospital discharge. Secondary outcomes included the modified Rankin scale score (on a scale from 0 to 6, with a score of ≤3 indicating favorable neurologic function). CPR process was measured to assess compliance. Of 23,711 patients included in the primary analysis, 12,653 were assigned to the intervention group and 11,058 to the control group. A total of 1129 of 12,613 patients with available data (9.0%) in the intervention group and 1072 of 11,035 with available data (9.7%) in the control group survived until discharge (difference, -0.7 percentage points; 95% confidence interval [CI], -1.5 to 0.1; P=0.07); 7.0% of the patients in the intervention group and 7.7% of those in the control group survived with favorable neurologic function at discharge (difference, -0.6 percentage points; 95% CI, -1.4 to 0.1, P=0.09). Hospital-free survival was significantly shorter in the intervention group than in the control group (mean difference, -0.2 days; 95% CI, -0.3 to -0.1; P=0.004). In patients with out-of-hospital cardiac arrest, continuous chest compressions during CPR performed by EMS providers did not result in significantly higher rates of survival or favorable neurologic function than did interrupted chest compressions

  14. Classification of Cardiopulmonary Resuscitation Chest Compression Patterns: Manual Versus Automated Approaches

    PubMed Central

    Wang, Henry E.; Schmicker, Robert H.; Herren, Heather; Brown, Siobhan; Donnelly, John P.; Gray, Randal; Ragsdale, Sally; Gleeson, Andrew; Byers, Adam; Jasti, Jamie; Aguirre, Christina; Owens, Pam; Condle, Joe; Leroux, Brian

    2015-01-01

    Objectives New chest compression detection technology allows for the recording and graphical depiction of clinical cardiopulmonary resuscitation (CPR) chest compressions. The authors sought to determine the inter-rater reliability of chest compression pattern classifications by human raters. Agreement with automated chest compression classification was also evaluated by computer analysis. Methods This was an analysis of chest compression patterns from cardiac arrest patients enrolled in the ongoing Resuscitation Outcomes Consortium (ROC) Continuous Chest Compressions Trial. Thirty CPR process files from patients in the trial were selected. Using written guidelines, research coordinators from each of eight participating ROC sites classified each chest compression pattern as 30:2 chest compressions, continuous chest compressions (CCC), or indeterminate. A computer algorithm for automated chest compression classification was also developed for each case. Inter-rater agreement between manual classifications was tested using Fleiss’s kappa. The criterion standard was defined as the classification assigned by the majority of manual raters. Agreement between the automated classification and the criterion standard manual classifications was also tested. Results The majority of the eight raters classified 12 chest compression patterns as 30:2, 12 as CCC, and six as indeterminate. Inter-rater agreement between manual classifications of chest compression patterns was κ = 0.62 (95% confidence interval [CI] = 0.49 to 0.74). The automated computer algorithm classified chest compression patterns as 30:2 (n = 15), CCC (n = 12), and indeterminate (n = 3). Agreement between automated and criterion standard manual classifications was κ = 0.84 (95% CI = 0.59 to 0.95). Conclusions In this study, good inter-rater agreement in the manual classification of CPR chest compression patterns was observed. Automated classification showed strong agreement with human ratings. These

  15. Manual Cardiopulmonary Resuscitation Versus CPR Including a Mechanical Chest Compression Device in Out-of-Hospital Cardiac Arrest: A Comprehensive Meta-analysis From Randomized and Observational Studies.

    PubMed

    Bonnes, Judith L; Brouwer, Marc A; Navarese, Eliano P; Verhaert, Dominique V M; Verheugt, Freek W A; Smeets, Joep L R M; de Boer, Menko-Jan

    2016-03-01

    Mechanical chest compression devices have been developed to facilitate continuous delivery of high-quality cardiopulmonary resuscitation (CPR). Despite promising hemodynamic data, evidence on clinical outcomes remains inconclusive. With the completion of 3 randomized controlled trials, we conduct a meta-analysis on the effect of in-field mechanical versus manual CPR on clinical outcomes after out-of-hospital cardiac arrest. With a systematic search (PubMed, Web of Science, EMBASE, and the Cochrane Libraries), we identified all eligible studies (randomized controlled trials and nonrandomized studies) that compared a CPR strategy including an automated mechanical chest compression device with a strategy of manual CPR only. Outcome variables were survival to hospital admission, survival to discharge, and favorable neurologic outcome. Twenty studies (n=21,363) were analyzed: 5 randomized controlled trials and 15 nonrandomized studies, pooled separately. For survival to admission, the pooled estimate of the randomized controlled trials did not indicate a difference (odds ratio 0.94; 95% confidence interval 0.84 to 1.05; P=.24) between mechanical and manual CPR. In contrast, meta-analysis of nonrandomized studies demonstrated a benefit in favor of mechanical CPR (odds ratio 1.42; 95% confidence interval 1.21 to 1.67; P<.001). No interaction was found between the endorsed CPR guidelines (2000 versus 2005) and the CPR strategy (P=.27). Survival to discharge and neurologic outcome did not differ between strategies. Although there are lower-quality, observational data that suggest that mechanical CPR used at the rescuer's discretion could improve survival to hospital admission, the cumulative high-quality randomized evidence does not support a routine strategy of mechanical CPR to improve survival or neurologic outcome. These findings are irrespective of the endorsed CPR guidelines during the study periods. Copyright © 2015 American College of Emergency Physicians

  16. Does the use of a chest compression system in children improve the effectiveness of chest compressions? A randomised crossover simulation pilot study.

    PubMed

    Szarpak, Łukasz; Truszewski, Zenon; Smereka, Jacek; Czyżewski, Łukasz

    2016-01-01

    Providing high-quality chest compressions is a key element affecting the effectiveness of cardiopulmonary resuscitation (CPR). To evaluate the effectiveness of standard (manual) chest compressions (Standard BLS, standard basic life support) and those performed with the use of the Lifeline ARM chest compression system (ARM; Defibtech). The study was designed as a randomised crossover study. In total, 37 nurses participated in the study. They performed a randomized 2-min asynchronous resuscitation using the Standard BLS method or the ARM system. The following parameters were measured: the total number of chest compressions, the frequency of compressions (min-1), compression depth (mm), and the percentage of correctly performed chest compressions and total chest decompressions. The authors also analysed the participants' preferences concerning the use of particular CPR techniques in the clinical setting. The results obtained during the simulation study with the application of the ARM system were statistically significantly better than those with the Standard BLS method (p < 0.05) in the case of all analysed parameters. During the simulated child resuscitation performed by the nurses, the application of the Lifeline ARM chest compression system significantly improved the effectiveness of chest compressions.

  17. Rhythm analysis and charging during chest compressions reduces compression pause time.

    PubMed

    Partridge, R; Tan, Q; Silver, A; Riley, M; Geheb, F; Raymond, R

    2015-05-01

    Prolonged chest compression interruptions immediately preceding and following a defibrillation shock reduce shock success and survival after cardiac arrest. We tested the hypothesis that compression pauses would be shorter using an AED equipped with a new Analysis during Compressions with Fast Reconfirmation (ADC-FR) technology, which features automated rhythm analysis and charging during compressions with brief reconfirmation analysis during compression pause, compared with standard AED mode. BLS-certified emergency medical technicians (EMTs) worked in pairs and performed two trials of simulated cardiac resuscitation with a chest compression sensing X Series defibrillator (ZOLL Medical). Each pair was randomized to perform a trial of eight 2-min compression intervals (randomly assigned to receive four shockable and four non-shockable rhythms) with the defibrillator in standard AED mode and another trial in ADC-FR mode. Subjects were advised to follow defibrillator prompts, defibrillate if "shock advised," and switch compressors every two intervals. Compression quality data were reviewed using RescueNet Code Review (ZOLL Medical) and analyzed using paired t-tests. Thirty-two EMT-basic prehospital providers (59% male; median 25 years age [IQR 22-27]) participated in the study. End of interval compression interruptions were significantly reduced with ADC-FR vs. AED mode (p<0.001). For shockable rhythms, pre-shock pause was reduced significantly with ADC-FR compared with AED use (7.35±0.16s vs. 12.0±0.22s, p<0.001) whereas post-shock pause was similar (2.08±0.14s vs. 1.77±0.14s, p=0.1). Chest compression interruptions associated with rhythm analysis and charging are reduced with use of a novel defibrillator technology, ADC-FR, which features automated rhythm analysis and charging during compressions. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  18. Active compression-decompression resuscitation: the influence of different chest geometries on the force transmission.

    PubMed

    Haid, C; Rabl, W; Baubin, M

    1997-08-01

    Active compression-decompression cardiopulmonary resuscitation (ACD-CPR) is performed using a plunger-like suction device applied onto the chest. Forces are partly transferred through the center of this device as well as through the peripheral ring of the plunger's lip seal. We analysed the load transmission distribution of the Ambu CardioPump; therefore a homemade mechanical model was used for simulating different chest geometries. We applied compression forces up to 750N on the device using a 'material testing machine', and we determined the load transferred through the central part of the device and the peripheral ring respectively. The results show that the deeper the sternum is inbeded in the chest the more force is distributed onto the peripheral ring of the plunger's vacuum cup. For a simulated flat chest, 70 N was transferred through the peripheral ring; at a simulated sternal depression of 20 mm, more than 300 N were transferred peripherally. This study points out that different chest geometries have to be considered when using CardioPump.

  19. Simulation intervention with manikin-based objective metrics improves CPR instructor chest compression performance skills without improvement in chest compression assessment skills.

    PubMed

    Al-Rasheed, Rakan S; Devine, Jeffrey; Dunbar-Viveiros, Jennifer A; Jones, Mark S; Dannecker, Max; Machan, Jason T; Jay, Gregory D; Kobayashi, Leo

    2013-08-01

    Cardiopulmonary resuscitation (CPR) instructor/coordinator (CPR-I/C) adherence to published guidelines during resuscitation and learner assessment for basic life support (BLS)/CPR skills has not been experimentally studied. Investigators sought to (1) determine the quality of CPR-I/C chest compression and the accuracy of CPR-I/C chest compression assessment, and (2) improve CPR-I/C compression and assessment skills through cardiac arrest simulations with objective in-scenario performance feedback. Thirty CPR-I/Cs (median, 20 years [range, 4-40 years] of BLS provider experience; 6 years [range 1-40 years] of BLS instructor experience) were randomized to control or experimental group. Each subject performed compressions during a 2-minute simulation, then reviewed 6 videos of simulated CPR performances (featuring prespecified chest compression parameters) for scoring as "pass" or "needs remediation." Subjects participated in a second simulation with or without real-time manikin compression feedback, then reviewed 6 additional videos. Primary outcome variables were the proportion of subjects with more than 80% (American Heart Association regional criteria) or more than 23 of 30 (ie, 77%; American Heart Association instructor manual criteria) correct compressions and subjects' accuracy of "pass"/"needs remediation" assessment for videos. The secondary outcome variable was correlation between subjects' correctness of chest compressions and their assessment accuracy for simulated CPR compression performance. All CPR-I/C subjects compressed suboptimally at baseline; real-time manikin feedback improved the proportion of subjects with more than 77% correct compressions to 0.53 (P < 0.01). Video review data revealed persistently low CPR-I/C assessment accuracy. Correlation between subjects' correctness of compressions and their assessment accuracy remained poor regardless of interventions. Real-time compression feedback during simulation improved CPR-I/C's chest compression

  20. Chest compressions in newborn animal models: A review.

    PubMed

    Solevåg, Anne Lee; Cheung, Po-Yin; Lie, Helene; O'Reilly, Megan; Aziz, Khalid; Nakstad, Britt; Schmölzer, Georg Marcus

    2015-11-01

    Much of the knowledge about the optimal way to perform chest compressions (CC) in newborn infants is derived from animal studies. The objective of this review was to identify studies of CC in newborn term animal models and review the evidence. We also provide an overview of the different models. MEDLINE, EMBASE and CINAHL, until September 29th 2014. Study eligibility criteria and interventions: term newborn animal models where CC was performed. Based on 419 retrieved studies from MEDLINE and 502 from EMBASE, 28 studies were included. No additional studies were identified in CINAHL. Most of the studies were performed in pigs after perinatal transition without long-term follow-up. The models differed widely in methodological aspects, which limits the possibility to compare and synthesize findings. Studies uncommonly reported the method for randomization and allocation concealment, and a limited number were blinded. Only the evidence in favour of the two-thumb encircling hands technique for performing CC, a CC to ventilation ratio of 3:1; and that air can be used for ventilation during CC; was supported by more than one study. Animal studies should be performed and reported with the same rigor as in human randomized trials. Good transitional and survival models are needed to further increase the strength of the evidence derived from animal studies of newborn chest compressions. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  1. Closed-loop controller for chest compressions based on coronary perfusion pressure: a computer simulation study.

    PubMed

    Wang, Chunfei; Zhang, Guang; Wu, Taihu; Zhan, Ningbo; Wang, Yaling

    2016-03-01

    High-quality cardiopulmonary resuscitation contributes to cardiac arrest survival. The traditional chest compression (CC) standard, which neglects individual differences, uses unified standards for compression depth and compression rate in practice. In this study, an effective and personalized CC method for automatic mechanical compression devices is provided. We rebuild Charles F. Babbs' human circulation model with a coronary perfusion pressure (CPP) simulation module and propose a closed-loop controller based on a fuzzy control algorithm for CCs, which adjusts the CC depth according to the CPP. Compared with a traditional proportion-integration-differentiation (PID) controller, the performance of the fuzzy controller is evaluated in computer simulation studies. The simulation results demonstrate that the fuzzy closed-loop controller results in shorter regulation time, fewer oscillations and smaller overshoot than traditional PID controllers and outperforms the traditional PID controller for CPP regulation and maintenance.

  2. Chest compression rates and survival following out-of-hospital cardiac arrest.

    PubMed

    Idris, Ahamed H; Guffey, Danielle; Pepe, Paul E; Brown, Siobhan P; Brooks, Steven C; Callaway, Clifton W; Christenson, Jim; Davis, Daniel P; Daya, Mohamud R; Gray, Randal; Kudenchuk, Peter J; Larsen, Jonathan; Lin, Steve; Menegazzi, James J; Sheehan, Kellie; Sopko, George; Stiell, Ian; Nichol, Graham; Aufderheide, Tom P

    2015-04-01

    Guidelines for cardiopulmonary resuscitation recommend a chest compression rate of at least 100 compressions/min. A recent clinical study reported optimal return of spontaneous circulation with rates between 100 and 120/min during cardiopulmonary resuscitation for out-of-hospital cardiac arrest. However, the relationship between compression rate and survival is still undetermined. Prospective, observational study. Data is from the Resuscitation Outcomes Consortium Prehospital Resuscitation IMpedance threshold device and Early versus Delayed analysis clinical trial. Adults with out-of-hospital cardiac arrest treated by emergency medical service providers. None. Data were abstracted from monitor-defibrillator recordings for the first five minutes of emergency medical service cardiopulmonary resuscitation. Multiple logistic regression assessed odds ratio for survival by compression rate categories (<80, 80-99, 100-119, 120-139, ≥140), both unadjusted and adjusted for sex, age, witnessed status, attempted bystander cardiopulmonary resuscitation, location of arrest, chest compression fraction and depth, first rhythm, and study site. Compression rate data were available for 10,371 patients; 6,399 also had chest compression fraction and depth data. Age (mean±SD) was 67±16 years. Chest compression rate was 111±19 per minute, compression fraction was 0.70±0.17, and compression depth was 42±12 mm. Circulation was restored in 34%; 9% survived to hospital discharge. After adjustment for covariates without chest compression depth and fraction (n=10,371), a global test found no significant relationship between compression rate and survival (p=0.19). However, after adjustment for covariates including chest compression depth and fraction (n=6,399), the global test found a significant relationship between compression rate and survival (p=0.02), with the reference group (100-119 compressions/min) having the greatest likelihood for survival. After adjustment for chest

  3. Chest Compression With Personal Protective Equipment During Cardiopulmonary Resuscitation

    PubMed Central

    Chen, Jie; Lu, Kai-Zhi; Yi, Bin; Chen, Yan

    2016-01-01

    Abstract Following a chemical, biological, radiation, and nuclear incident, prompt cardiopulmonary resuscitation (CPR) procedure is essential for patients who suffer cardiac arrest. But CPR when wearing personal protection equipment (PPE) before decontamination becomes a challenge for healthcare workers (HCW). Although previous studies have assessed the impact of PPE on airway management, there is little research available regarding the quality of chest compression (CC) when wearing PPE. A present randomized cross-over simulation study was designed to evaluate the effect of PPE on CC performance using mannequins. The study was set in one university medical center in the China. Forty anesthesia residents participated in this randomized cross-over study. Each participant performed 2 min of CC on a manikin with and without PPE, respectively. Participants were randomized into 2 groups that either performed CC with PPE first, followed by a trial without PPE after a 180-min rest, or vice versa. CPR recording technology was used to objectively quantify the quality of CC. Additionally, participants’ physiological parameters and subjective fatigue score values were recorded. With the use of PPE, a significant decrease of the percentage of effective compressions (41.3 ± 17.1% with PPE vs 67.5 ± 15.6% without PPE, P < 0.001) and the percentage of adequate compressions (67.7 ± 18.9% with PPE vs 80.7 ± 15.5% without PPE, P < 0.001) were observed. Furthermore, the increases in heart rate, mean arterial pressure, and subjective fatigue score values were more obvious with the use of PPE (all P < 0.01). We found significant deterioration of CC performance in HCW with the use of a level-C PPE, which may be a disadvantage for enhancing survival of cardiac arrest. PMID:27057878

  4. Analysis of actual pressure point using the power flexible capacitive sensor during chest compression.

    PubMed

    Minami, Kouichiro; Kokubo, Yota; Maeda, Ichinosuke; Hibino, Shingo

    2017-02-01

    In chest compression for cardiopulmonary resuscitation (CPR), the lower half of the sternum is pressed according to the American Heart Association (AHA) guidelines 2010. These have been no studies which identify the exact location of the applied by individual chest compressions. We developed a rubber power-flexible capacitive sensor that could measure the actual pressure point of chest compression in real time. Here, we examined the pressure point of chest compression by ambulance crews during CPR using a mannequin. We included 179 ambulance crews. Chest compression was performed for 2 min. The pressure position was monitored, and the quality of chest compression was analyzed by using a flexible pressure sensor (Shinnosukekun™). Of the ambulance crews, 58 (32.4 %) pressed the center and 121 (67.6 %) pressed outside the proper area of chest compression. Many of them pressed outside the center; 8, 7, 41, and 90 pressed on the caudal, left, right, and cranial side, respectively. Average compression rate, average recoil, average depth, and average duty cycle were 108.6 counts per minute, 0.089, 4.5 cm, and 48.27 %, respectively. Many of the ambulance crews did not press on the sternal lower half definitely. This new device has the potential to improve the quality of CPR during training or in clinical practice.

  5. Optimal chest compression rate in cardiopulmonary resuscitation: a prospective, randomized crossover study using a manikin model.

    PubMed

    Lee, Seong Hwa; Ryu, Ji Ho; Min, Mun Ki; Kim, Yong In; Park, Maeng Real; Yeom, Seok Ran; Han, Sang Kyoon; Park, Seong Wook

    2016-08-01

    When performing cardiopulmonary resuscitation (CPR), the 2010 American Heart Association guidelines recommend a chest compression rate of at least 100 min, whereas the 2010 European Resuscitation Council guidelines recommend a rate of between 100 and 120 min. The aim of this study was to examine the rate of chest compression that fulfilled various quality indicators, thereby determining the optimal rate of compression. Thirty-two trainee emergency medical technicians and six paramedics were enrolled in this study. All participants had been trained in basic life support. Each participant performed 2 min of continuous compressions on a skill reporter manikin, while listening to a metronome sound at rates of 100, 120, 140, and 160 beats/min, in a random order. Mean compression depth, incomplete chest recoil, and the proportion of correctly performed chest compressions during the 2 min were measured and recorded. The rate of incomplete chest recoil was lower at compression rates of 100 and 120 min compared with that at 160 min (P=0.001). The numbers of compressions that fulfilled the criteria for high-quality CPR at a rate of 120 min were significantly higher than those at 100 min (P=0.016). The number of high-quality CPR compressions was the highest at a compression rate of 120 min, and increased incomplete recoil occurred with increasing compression rate. However, further studies are needed to confirm the results.

  6. Addition of a video camera system improves the ease of Airtraq(®) tracheal intubation during chest compression.

    PubMed

    Kohama, Hanako; Komasawa, Nobuyasu; Ueki, Ryusuke; Itani, Motoi; Nishi, Shin-ichi; Kaminoh, Yoshiroh

    2012-04-01

    Recent resuscitation guidelines for cardiopulmonary resuscitation emphasize that rescuers should perform tracheal intubation with minimal interruption of chest compressions. We evaluated the use of video guidance to facilitate tracheal intubation with the Airtraq (ATQ) laryngoscope during chest compression. Eighteen novice physicians in our anesthesia department performed tracheal intubation on a manikin using the ATQ with a video camera system (ATQ-V) or with no video guidance (ATQ-N) during chest compression. All participants were able to intubate the manikin using the ATQ-N without chest compression, but five failed during chest compression (P < 0.05). In contrast, all participants successfully secured the airway with the ATQ-V, with or without chest compression. Concurrent chest compression increased the time required for intubation with the ATQ-N (without chest compression 14.8 ± 4.5 s; with chest compression, 28.2 ± 10.6 s; P < 0.05), but not with the ATQ-V (without chest compression, 15.9 ± 5.8 s; with chest compression, 17.3 ± 5.3 s; P > 0.05). The ATQ video camera system improves the ease of tracheal intubation during chest compressions.

  7. Comparisons of the Pentax-AWS, Glidescope, and Macintosh Laryngoscopes for Intubation Performance during Mechanical Chest Compressions in Left Lateral Tilt: A Randomized Simulation Study of Maternal Cardiopulmonary Resuscitation

    PubMed Central

    Lee, Sanghyun; Kim, Wonhee; Kang, Hyunggoo; Oh, Jaehoon; Lim, Tae Ho; Lee, Yoonjae; Kim, Changsun; Cho, Jun Hwi

    2015-01-01

    Purpose. Rapid advanced airway management is important in maternal cardiopulmonary resuscitation (CPR). This study aimed to compare intubation performances among Pentax-AWS (AWS), Glidescope (GVL), and Macintosh laryngoscope (MCL) during mechanical chest compression in 15° and 30° left lateral tilt. Methods. In 19 emergency physicians, a prospective randomized crossover study was conducted to examine the three laryngoscopes. Primary outcomes were the intubation time and the success rate for intubation. Results. The median intubation time using AWS was shorter than that of GVL and MCL in both tilt degrees. The time to visualize the glottic view in GVL and AWS was significantly lower than that of MCL (all P < 0.05), whereas there was no significant difference between the two video laryngoscopes (in 15° tilt, P = 1; in 30° tilt, P = 0.71). The progression of tracheal tube using AWS was faster than that of MCL and GVL in both degrees (all P < 0.001). Intubations using AWS and GVL showed higher success rate than that of Macintosh laryngoscopes. Conclusions. The AWS could be an appropriate laryngoscope for airway management of pregnant women in tilt CPR considering intubation time and success rate. PMID:26161426

  8. Hands-on defibrillation during active chest compressions: eliminating another interruption.

    PubMed

    Brady, William; Berlat, Joshua A

    2016-11-01

    After decades of research, effective chest compressions have emerged as a key component of high-quality cardiopulmonary resuscitation (CPR) for cardiac arrest patients. Minimizing interruptions in chest compressions is garnering increasing attention as a method to improve CPR quality and outcomes. Hands-on defibrillation has been suggested as both a safe and effective means of reducing interruptions in chest compressions. This article discusses the safety and efficacy of a novel and controversial method to reduce interruptions: hands-on defibrillation. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Defibrillation delivered during the upstroke phase of manual chest compression improves shock success.

    PubMed

    Li, Yongqin; Wang, Hao; Cho, Jun Hwi; Quan, Weilun; Freeman, Gary; Bisera, Joe; Weil, Max Harry; Tang, Wanchun

    2010-03-01

    The current standard of manual chest compression during cardiopulmonary resuscitation requires pauses for rhythm analysis and shock delivery. However, interruptions of chest compression greatly decrease the likelihood of successful defibrillations, and significantly better outcomes are reported if this interruption is avoided. We therefore undertook a prospective randomized controlled animal study in an electrically induced ventricular fibrillation pig model to assess the effects of timing of defibrillation on the manual chest compression cycle on the defibrillation threshold. Prospective, randomized, controlled animal study. University-affiliated research laboratory. Yorkshire-X domestic pigs (Sus scrofa). In eight domestic male pigs weighing between 24 and 31 kg, ventricular fibrillation was electrically induced and untreated for 10 secs. Manual chest compression was then performed and continued for 25 secs with the protection of an isolation blanket. The depth and frequency of chest compressions were guided by a cardiopulmonary resuscitation prompter. Animals were randomized to receive a biphasic electrical shock in five different compression phases with a predetermined energy setting. A control phase was chosen at a constant 2 secs after discontinued chest compression. A grouped up-down defibrillation threshold testing protocol was used to compare the success rate at different coupling phases. After a recovery interval of 4 mins, the sequence was repeated for a total of 60 test shocks for each animal. No difference in coronary perfusion pressure before delivering of the shock was observed among the six study phases. The defibrillation success rate, however, was significantly higher when shocks were delivered in the upstroke phase of manual chest compression. Defibrillation efficacy is maximal when electrical shock is delivered during the upstroke phase of manual chest compression.

  10. Airway pressure with chest compressions versus Heimlich manoeuvre in recently dead adults with complete airway obstruction.

    PubMed

    Langhelle, A; Sunde, K; Wik, L; Steen, P A

    2000-04-01

    In a previous case report a standard chest compression successfully removed a foreign body from the airway after the Heimlich manoeuvre had failed. Based on this case, standard chest compressions and Heimlich manoeuvres were performed by emergency physicians on 12 unselected cadavers with a simulated complete airway obstruction in a randomised crossover design. The mean peak airway pressure was significantly lower with abdominal thrusts compared to chest compressions, 26.4+/-19.8 cmH(2)O versus 40.8+/-16.4 cmH(2)O, respectively (P=0.005, 95% confidence interval for the mean difference 5.3-23.4 cmH(2)O). Standard chest compressions therefore have the potential of being more effective than the Heimlich manoeuvre for the management of complete airway obstruction by a foreign body in an unconscious patient. Removal of the Heimlich manoeuvre from the resuscitation algorithm for unconscious patients with suspected airway obstruction will also simplify training.

  11. Compressing with dominant hand improves quality of manual chest compressions for rescuers who performed suboptimal CPR in manikins.

    PubMed

    Wang, Juan; Tang, Ce; Zhang, Lei; Gong, Yushun; Yin, Changlin; Li, Yongqin

    2015-07-01

    The question of whether the placement of the dominant hand against the sternum could improve the quality of manual chest compressions remains controversial. In the present study, we evaluated the influence of dominant vs nondominant hand positioning on the quality of conventional cardiopulmonary resuscitation (CPR) during prolonged basic life support (BLS) by rescuers who performed optimal and suboptimal compressions. Six months after completing a standard BLS training course, 101 medical students were instructed to perform adult single-rescuer BLS for 8 minutes on a manikin with a randomized hand position. Twenty-four hours later, the students placed the opposite hand in contact with the sternum while performing CPR. Those with an average compression depth of less than 50 mm were considered suboptimal. Participants who had performed suboptimal compressions were significantly shorter (170.2 ± 6.8 vs 174.0 ± 5.6 cm, P = .008) and lighter (58.9 ± 7.6 vs 66.9 ± 9.6 kg, P < .001) than those who performed optimal compressions. No significant differences in CPR quality were observed between dominant and nondominant hand placements for these who had an average compression depth of greater than 50 mm. However, both the compression depth (49.7 ± 4.2 vs 46.5 ± 4.1 mm, P = .003) and proportion of chest compressions with an appropriate depth (47.6% ± 27.8% vs 28.0% ± 23.4%, P = .006) were remarkably higher when compressing the chest with the dominant hand against the sternum for those who performed suboptimal CPR. Chest compression quality significantly improved when the dominant hand was placed against the sternum for those who performed suboptimal compressions during conventional CPR. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. A review of chest compression interruptions during out-of-hospital cardiac arrest and strategies for the future.

    PubMed

    Souchtchenko, Steven S; Benner, John P; Allen, Jessica L; Brady, William J

    2013-09-01

    It has been known for many years that interrupting chest compressions during cardiopulmonary resuscitation (CPR) from out-of-hospital cardiac arrest (OHCA) leads directly to negative outcomes. Interruptions in chest compressions occur for a variety of reasons, including provider fatigue and switching of compressors, performance of ventilations, placement of invasive airways, application of CPR devices, pulse and rhythm determinations, vascular access placement, and patient transfer to the ambulance. Despite significant resuscitation guideline changes in the last decade, several studies have shown that chest compressions are still frequently interrupted or poorly executed during OHCA resuscitations. Indeed, the American Heart Association has made great strides to improve outcomes by placing a greater emphasis on uninterrupted chest compressions. As highly trained health care providers, why do we still interrupt chest compressions? And are any of these interruptions truly necessary? This article aims to review the clinical effects of both high-quality chest compressions and the effects that interruptions during chest compressions have clinically on patient outcomes. The causes of chest compression interruptions are explored from both provider and team perspectives. Current and future methods are introduced that may prompt the provider to reduce unnecessary interruptions during chest compressions. New and future technologies may provide promising results, but the greatest benefit will always be a well-directed, organized, and proactive team of providers performing excellent-quality and continuous chest compressions during CPR. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Use of step stool during resuscitation improved the quality of chest compression in simulated resuscitation.

    PubMed

    Lee, Dong Hoon; Kim, Chan Woong; Kim, Sung Eun; Lee, Sang Jin

    2012-08-01

    Resuscitation on a medical bed is difficult because of the need to match the height of the bed to the height of the rescuer, which is impossible on a fixed-height medical bed. This study investigated the effect of using a step stool on chest compressions performed on a manikin in a fixed-height medical bed. This prospective, observational study was performed using simulated resuscitation manikins and a fixed-height (78 cm) medical bed. Chest compression-ventilation of more than five cycles was performed with and without a 20-cm-high step stool. A total of 74 medical students participated in this study. The quality of the chest compressions was examined using the Laerdal PC Skill Reporting System. The angle between the arm of the rescuer and the bed was measured. In addition, whether the heels of the rescuer reached the ground during the compressions was assessed using lateral-view pictures. Use of the step stool improved the quality of the chest compressions with regard to depth, proper compressions, insufficient compressions and incorrect hand position (P < 0.05). The angle between the rescuer's arm and bed during the chest compressions was closer to vertical with the use of the step stool than without it (average angle, 83.84 ± 4.16° and 73.41 ± 9.16°, respectively; P < 0.001). In-hospital resuscitation was conducted on a fixed-height medical bed by rescuers of different heights. The use of a step stool may improve the quality and effectiveness of chest compressions, particularly for short rescuers. © 2012 The Authors. EMA © 2012 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

  14. Cardiopulmonary resuscitation for cardiac arrest: the importance of uninterrupted chest compressions in cardiac arrest resuscitation.

    PubMed

    Cunningham, Lee M; Mattu, Amal; O'Connor, Robert E; Brady, William J

    2012-10-01

    Over the last decade, the importance of delivering high-quality cardiopulmonary resuscitation (CPR) for cardiac arrest patients has become increasingly emphasized. Many experts are in agreement concerning the appropriate compression rate, depth, and amount of chest recoil necessary for high-quality CPR. In addition to these factors, there is a growing body of evidence supporting continuous or uninterrupted chest compressions as an equally important aspect of high-quality CPR. An innovative resuscitation protocol, called cardiocerebral resuscitation, emphasizes uninterrupted chest compressions and has been associated with superior rates of survival when compared with traditional CPR with standard advanced life support. Interruptions in chest compressions during CPR can negatively impact outcome in cardiac arrest; these interruptions occur for a range of reasons, including pulse determinations, cardiac rhythm analysis, electrical defibrillation, airway management, and vascular access. In addition to comparing cardiocerebral resuscitation to CPR, this review article also discusses possibilities to reduce interruptions in chest compressions without sacrificing the benefit of these interventions. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Panic Disorder and Chest Pain: Mechanisms, Morbidity, and Management.

    PubMed

    Huffman, Jeff C.; Pollack, Mark H.; Stern, Theodore A.

    2002-04-01

    Approximately one quarter of patients who present to physicians for treatment of chest pain have panic disorder. Panic disorder frequently goes unrecognized and untreated among patients with chest pain, leading to frequent return visits and substantial morbidity. Panic attacks may lead to chest pain through a variety of mechanisms, both cardiac and noncardiac in nature, and multiple processes may cause chest pain in the same patient. Panic disorder is associated with elevated rates of cardiovascular diseases, including hypertension, cardiomyopathy, and, possibly, sudden cardiac death. Furthermore, patients with panic disorder and chest pain have high rates of functional disability and medical service utilization. Fortunately, panic disorder is treatable; selective serotonin reuptake inhibitors, benzodiazepines, and cognitive-behavioral psychotherapy all effectively reduce symptoms. Preliminary studies have also found that treatment of patients who have panic disorder and chest pain with benzodiazepines results in reduction of chest pain as well as relief of anxiety.

  16. Association between chest compression rates and clinical outcomes following in-hospital cardiac arrest at an academic tertiary hospital.

    PubMed

    Kilgannon, J Hope; Kirchhoff, Michael; Pierce, Lisa; Aunchman, Nicholas; Trzeciak, Stephen; Roberts, Brian W

    2017-01-01

    Recent guidelines for management of cardiac arrest recommend chest compression rates of 100-120 compressions/min. However, animal studies have found cardiac output to increase with rates up to 150 compressions/min. The objective of this study was to test the association between chest compression rates during cardiopulmonary resuscitation for in-hospital cardiac arrest (IHCA) and outcome. We conducted a prospective observational study at a single academic medical center. age≥18, IHCA, cardiopulmonary resuscitation performed. We analyzed chest compression rates measured by defibrillation electrodes, which recorded changes in thoracic impedance. The primary outcome was return of spontaneous circulation (ROSC). We used multivariable logistic regression to determine odds ratios for ROSC by chest compression rate categories (100-120, 121-140, >140 compressions/min), adjusted for chest compression fraction (proportion of time chest compressions provided) and other known predictors of outcome. We set 100-120 compressions/min as the reference category for the multivariable model. We enrolled 222 consecutive patients and found a mean chest compression rate of 139±15. Overall 53% achieved ROSC; among 100-120, 121-140, and >140 compressions/min, ROSC was 29%, 64%, and 49% respectively. A chest compression rate of 121-140 compressions/min had the greatest likelihood of ROSC, odds ratio 4.48 (95% CI 1.42-14.14). In this sample of adult IHCA patients, a chest compression rate of 121-140 compressions/min had the highest odds ratio of ROSC. Rates above the currently recommended 100-120 compressions/min may improve the chances of ROSC among IHCA patients. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. Estimation of optimal pediatric chest compression depth by using computed tomography

    PubMed Central

    Jin, Soo Young; Oh, Seong Beom; Kim, Young Oh

    2016-01-01

    Objective This study aimed to compare the optimal chest compression depth for infants and children with that of adults when the simulated compression depth was delivered according to the current guidelines. Methods A total of 467 consecutive chest computed tomography scans (93 infants, 110 children, and 264 adults) were reviewed. The anteroposterior diameter and compressible diameter (CD) for infants and children were measured at the inter-nipple level and at the mid-lower half of the spine for adults. Compression ratio (CR) to CD was calculated at simulated 1/4, 1/3, and 1/2 antero-posterior compressions in infants and children, and simulated 5- and 6-cm compressions in adults. Results In adults, the CRs to CD at simulated 5- and 6-cm compression depth were 41.7±0.16%, 50.0±7.3% respectively. In children and infants, the CRs to CD at 1/3 chest compression were 55.1±2.4% and 51.8±2.4%, respectively, and at 1/2 chest compression, CRs were 82.7±3.7% and 77.7±3.6%, respectively. The CRs to CD of 4-cm compression depth in infants and 5-cm compression depth in children were 74.4±10.9%, 62.5±8.7%, respectively. The CRs to CD for children and infants were significantly higher than in adults (P<0.001). The CR to CD of 4-cm compression depth in children was almost similar to that of 6-cm compression depth in adults (50.0± 6.9% vs. 50.0±7.3%, P=0.985). Conclusion Current pediatric guidelines for compression depth are too deep compared to those in adults. We suggest using 1/3 of the anteroposterior chest diameter or about 4 cm in children and less than 4 cm in infants. PMID:27752612

  18. Accuracy of instructor assessment of chest compression quality during simulated resuscitation.

    PubMed

    Brennan, Erin E; McGraw, Robert C; Brooks, Steven C

    2016-07-01

    The 2010 American Heart Association Guidelines stress the importance of high quality cardiopulmonary resuscitation (CPR) as a predictor of survival from cardiac arrest. However, resuscitation training is often facilitated and evaluated by instructors without access to objective measures of CPR quality. This study aims to determine whether instructors experienced in the area of adult resuscitation (emergency department staff and senior residents) can accurately assess the quality of chest compressions as a component of their global assessment of a simulated resuscitation scenario. This is a prospective observational study in which objective chest compression quality data (rate, depth, and fraction) were collected from the simulation manikin and compared to subjective instructor assessment. Data were collected during weekly simulation training sessions for residents, medical students, and nursing students. We included data from 24 simulated resuscitation scenarios assessed by 1 of 15 instructors. Subjective assessment of chest compression quality identified an adequate compression rate (100-120 compressions per minute) with a sensitivity of 0.17 (confidence interval [CI] 0.02-0.32) and specificity of 0.06 (CI -0.04-0.15), adequate depth (>50 mm) with a sensitivity of 0 and specificity of 0.38 (CI 0.18-0.57), and adequate fraction (>80%) with a sensitivity of 1 and a specificity of 0.25 (CI 0.08-0.42). Instructor assessment of chest compression rate, depth, and fraction demonstrates poor sensitivity and specificity when compared to the data from the simulation manikin. These results support the use of objective and technologically supported measures of chest compression quality for feedback during resuscitation education using simulators.

  19. Effect of Using an Audiovisual CPR Feedback Device on Chest Compression Rate and Depth.

    PubMed

    Wee, Jeremy C P; Nandakumar, Mooppil; Chan, Yiong Huak; Yeo, Rowena S L; Kaur, Kaldip; Anantharaman, V; Yap, Susan; Ong, Marcus E H

    2014-01-01

    The aim of the study is to investigate the effect of using Automated External Defibrillator (AED) audiovisual feedback on the quality of cardiopulmonary resuscitation (CPR) in a manikin training setting. Five cycles of 30 chest compressions were performed on a manikin without CPR prompts. After an interval of at least 5 minutes, the participants performed another 5 cycles with the use of real time audiovisual feedback via the ZOLL E-Series defibrillator. Performance data were obtained and analysed. A total of 209 dialysis centre staff participated in the study. Using a feedback system resulted in a statistically significant improvement from 39.57% to 46.94% (P=0.009) of the participants being within the target compression depth of 4 cm to 5 cm and a reduction in those below target from 16.45% to 11.05% (P=0.004). The use of feedback also produced a significant improvement in achieving the target for rate of chest compression (90 to 110 compressions per minute) from 41.27% to 53.49%; (P<0.001). The mean depth of chest compressions was 4.85 cm (SD=0.79) without audiovisual feedback and 4.91 (SD=0.69) with feedback. For rate of chest compressions, it was 104.89 (SD=13.74) vs 101.65 (SD=10.21) respectively. The mean depth of chest compression was less in males than in females (4.61 cm vs 4.93 cm, P=0.011), and this trend was reversed with the use of feedback. In conclusion, the use of feedback devices helps to improve the quality of CPR during training. However more studies involving cardiac arrest patients requiring CPR need to be done to determine if these devices improve survival.

  20. A simple accurate chest-compression depth gauge using magnetic coils during cardiopulmonary resuscitation.

    PubMed

    Kandori, Akihiko; Sano, Yuko; Zhang, Yuhua; Tsuji, Toshio

    2015-12-01

    This paper describes a new method for calculating chest compression depth and a simple chest-compression gauge for validating the accuracy of the method. The chest-compression gauge has two plates incorporating two magnetic coils, a spring, and an accelerometer. The coils are located at both ends of the spring, and the accelerometer is set on the bottom plate. Waveforms obtained using the magnetic coils (hereafter, "magnetic waveforms"), which are proportional to compression-force waveforms and the acceleration waveforms were measured at the same time. The weight factor expressing the relationship between the second derivatives of the magnetic waveforms and the measured acceleration waveforms was calculated. An estimated-compression-displacement (depth) waveform was obtained by multiplying the weight factor and the magnetic waveforms. Displacements of two large springs (with similar spring constants) within a thorax and displacements of a cardiopulmonary resuscitation training manikin were measured using the gauge to validate the accuracy of the calculated waveform. A laser-displacement detection system was used to compare the real displacement waveform and the estimated waveform. Intraclass correlation coefficients (ICCs) between the real displacement using the laser system and the estimated displacement waveforms were calculated. The estimated displacement error of the compression depth was within 2 mm (<1 standard deviation). All ICCs (two springs and a manikin) were above 0.85 (0.99 in the case of one of the springs). The developed simple chest-compression gauge, based on a new calculation method, provides an accurate compression depth (estimation error < 2 mm).

  1. A simple accurate chest-compression depth gauge using magnetic coils during cardiopulmonary resuscitation

    NASA Astrophysics Data System (ADS)

    Kandori, Akihiko; Sano, Yuko; Zhang, Yuhua; Tsuji, Toshio

    2015-12-01

    This paper describes a new method for calculating chest compression depth and a simple chest-compression gauge for validating the accuracy of the method. The chest-compression gauge has two plates incorporating two magnetic coils, a spring, and an accelerometer. The coils are located at both ends of the spring, and the accelerometer is set on the bottom plate. Waveforms obtained using the magnetic coils (hereafter, "magnetic waveforms"), which are proportional to compression-force waveforms and the acceleration waveforms were measured at the same time. The weight factor expressing the relationship between the second derivatives of the magnetic waveforms and the measured acceleration waveforms was calculated. An estimated-compression-displacement (depth) waveform was obtained by multiplying the weight factor and the magnetic waveforms. Displacements of two large springs (with similar spring constants) within a thorax and displacements of a cardiopulmonary resuscitation training manikin were measured using the gauge to validate the accuracy of the calculated waveform. A laser-displacement detection system was used to compare the real displacement waveform and the estimated waveform. Intraclass correlation coefficients (ICCs) between the real displacement using the laser system and the estimated displacement waveforms were calculated. The estimated displacement error of the compression depth was within 2 mm (<1 standard deviation). All ICCs (two springs and a manikin) were above 0.85 (0.99 in the case of one of the springs). The developed simple chest-compression gauge, based on a new calculation method, provides an accurate compression depth (estimation error < 2 mm).

  2. Feedback on the Rate and Depth of Chest Compressions during Cardiopulmonary Resuscitation Using Only Accelerometers

    PubMed Central

    Ruiz de Gauna, Sofía; González-Otero, Digna M.; Ruiz, Jesus; Russell, James K.

    2016-01-01

    Background Quality of cardiopulmonary resuscitation (CPR) is key to increase survival from cardiac arrest. Providing chest compressions with adequate rate and depth is difficult even for well-trained rescuers. The use of real-time feedback devices is intended to contribute to enhance chest compression quality. These devices are typically based on the double integration of the acceleration to obtain the chest displacement during compressions. The integration process is inherently unstable and leads to important errors unless boundary conditions are applied for each compression cycle. Commercial solutions use additional reference signals to establish these conditions, requiring additional sensors. Our aim was to study the accuracy of three methods based solely on the acceleration signal to provide feedback on the compression rate and depth. Materials and Methods We simulated a CPR scenario with several volunteers grouped in couples providing chest compressions on a resuscitation manikin. Different target rates (80, 100, 120, and 140 compressions per minute) and a target depth of at least 50 mm were indicated. The manikin was equipped with a displacement sensor. The accelerometer was placed between the rescuer’s hands and the manikin’s chest. We designed three alternatives to direct integration based on different principles (linear filtering, analysis of velocity, and spectral analysis of acceleration). We evaluated their accuracy by comparing the estimated depth and rate with the values obtained from the reference displacement sensor. Results The median (IQR) percent error was 5.9% (2.8–10.3), 6.3% (2.9–11.3), and 2.5% (1.2–4.4) for depth and 1.7% (0.0–2.3), 0.0% (0.0–2.0), and 0.9% (0.4–1.6) for rate, respectively. Depth accuracy depended on the target rate (p < 0.001) and on the rescuer couple (p < 0.001) within each method. Conclusions Accurate feedback on chest compression depth and rate during CPR is possible using exclusively the chest

  3. Clinical pilot study of different hand positions during manual chest compressions monitored with capnography.

    PubMed

    Qvigstad, Eric; Kramer-Johansen, Jo; Tømte, Øystein; Skålhegg, Tore; Sørensen, Øyvar; Sunde, Kjetil; Olasveengen, Theresa M

    2013-09-01

    Optimal hand position for chest compressions during cardiopulmonary resuscitation is unknown. Recent imaging studies indicate significant inter-individual anatomical variations, which might cause varying haemodynamic responses with standard chest compressions. This prospective clinical pilot study intended to assess the feasibility of utilizing capnography to optimize chest compressions and identify the optimal hand position. Intubated cardiac arrest patients treated by the physician manned ambulance between February and December 2011 monitored with continuous end-tidal CO2 (EtCO2) measurements were included. One minute of chest compressions at the inter-nipple line (INL) optimized using EtCO2 feedback, was followed by four 30-s intervals with compressions at four different sites; INL, 2 cm below the INL, 2 cm below and to the left of INL and 2 cm below and to the right of INL. Thirty patients were included. At the end of each 30-s interval median (range) EtCO2 was 3.1 kPa (0.7-8.7 kPa) at INL, 3.5 kPa (0.5-10.7) 2 cm below INL, 3.5 kPa (0.5-10.3 kPa) 2 cm below and to the left of INL, and 3.8 kPa (0.4-8.8 kPa) 2 cm below and to the right of INL (p=0.4). The EtCO2 difference within each subject between hand positions with maximum and minimum values varied between individuals from 0.2 to 3.4 kPa (median 0.9 kPa). Monitoring and optimizing chest compressions using capnography was feasible. We could not demonstrate one superior hand position, but inter-individual differences suggest optimal hand position might vary significantly among patients. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  4. Chest wall mechanics in sustained microgravity

    NASA Technical Reports Server (NTRS)

    Wantier, M.; Estenne, M.; Verbanck, S.; Prisk, G. K.; Paiva, M.; West, J. B. (Principal Investigator)

    1998-01-01

    We assessed the effects of sustained weightlessness on chest wall mechanics in five astronauts who were studied before, during, and after the 10-day Spacelab D-2 mission (n = 3) and the 180-day Euromir-95 mission (n = 2). We measured flow and pressure at the mouth and rib cage and abdominal volumes during resting breathing and during a relaxation maneuver from midinspiratory capacity to functional residual capacity. Microgravity produced marked and consistent changes (Delta) in the contribution of the abdomen to tidal volume [DeltaVab/(DeltaVab + DeltaVrc), where Vab is abdominal volume and Vrc is rib cage volume], which increased from 30.7 +/- 3. 5 (SE)% at 1 G head-to-foot acceleration to 58.3 +/- 5.7% at 0 G head-to-foot acceleration (P < 0.005). Values of DeltaVab/(DeltaVab + DeltaVrc) did not change significantly during the 180 days of the Euromir mission, but in the two subjects DeltaVab/(DeltaVab + DeltaVrc) was greater on postflight day 1 than on subsequent postflight days or preflight. In the two subjects who produced satisfactory relaxation maneuvers, the slope of the Konno-Mead plot decreased in microgravity; this decrease was entirely accounted for by an increase in abdominal compliance because rib cage compliance did not change. These alterations are similar to those previously reported during short periods of weightlessness inside aircrafts flying parabolic trajectories. They are also qualitatively similar to those observed on going from upright to supine posture; however, in contrast to microgravity, such postural change reduces rib cage compliance.

  5. Chest wall mechanics in sustained microgravity

    NASA Technical Reports Server (NTRS)

    Wantier, M.; Estenne, M.; Verbanck, S.; Prisk, G. K.; Paiva, M.; West, J. B. (Principal Investigator)

    1998-01-01

    We assessed the effects of sustained weightlessness on chest wall mechanics in five astronauts who were studied before, during, and after the 10-day Spacelab D-2 mission (n = 3) and the 180-day Euromir-95 mission (n = 2). We measured flow and pressure at the mouth and rib cage and abdominal volumes during resting breathing and during a relaxation maneuver from midinspiratory capacity to functional residual capacity. Microgravity produced marked and consistent changes (Delta) in the contribution of the abdomen to tidal volume [DeltaVab/(DeltaVab + DeltaVrc), where Vab is abdominal volume and Vrc is rib cage volume], which increased from 30.7 +/- 3. 5 (SE)% at 1 G head-to-foot acceleration to 58.3 +/- 5.7% at 0 G head-to-foot acceleration (P < 0.005). Values of DeltaVab/(DeltaVab + DeltaVrc) did not change significantly during the 180 days of the Euromir mission, but in the two subjects DeltaVab/(DeltaVab + DeltaVrc) was greater on postflight day 1 than on subsequent postflight days or preflight. In the two subjects who produced satisfactory relaxation maneuvers, the slope of the Konno-Mead plot decreased in microgravity; this decrease was entirely accounted for by an increase in abdominal compliance because rib cage compliance did not change. These alterations are similar to those previously reported during short periods of weightlessness inside aircrafts flying parabolic trajectories. They are also qualitatively similar to those observed on going from upright to supine posture; however, in contrast to microgravity, such postural change reduces rib cage compliance.

  6. Effects of the Cardio First AngelTM on chest compression performance.

    PubMed

    Guenther, S P W; Schirren, M; Boulesteix, A L; Busen, H; Poettinger, T; Pichlmaier, A M; Khaladj, N; Hagl, C

    2017-09-22

    Survival rates of out-of-hospital cardiac arrest remain poor. Bystander cardiopulmonary resuscitation (CPR) is crucial for survival and feedback devices could improve its quality. We investigated quality of chest compression when using the Cardio First AngelTM (CFA) feedback device compared to standard basic life support (BLS). The analysis focused on laymen. Laymen without (n= 43) and with (n= 96) explanation of the device, medical students (n= 128) and medical staff (n= 27) performed 60 seconds of standard versus assisted chest compression using the CFA on a resuscitation manikin. Compression frequency, depth and position were analyzed according to current guidelines. Laymen showed significantly better success rates regarding correct compression depth when using the CFA (23.3% vs. 55.8%, p= 0.004 and 25.0% vs. 52.1%, p< 0.001, laymen without and with explanation of the device, respectively). Medical students likewise improved (22.7% vs. 42.2%, p= 0.004). Hand positioning was 100% correct in all groups with the device. Improvement in frequency yielded by the CFA was more pronounced for probands with fears of contact (p= 0.02). The benefit of using the device did not differ significantly in laymen with or without explanation. Chest compression as performed by laymen was significantly improved with regard to compression depth when using the CFA for guidance and feedback. With the device, no cases of incorrect hand positioning occurred in any group.

  7. Comparison of Chest Compressions Metrics Measured Using the Laerdal Skill Reporter and Q-CPR: A Simulation Study.

    PubMed

    Davey, Paul; Whatman, Chris; Dicker, Bridget

    2015-10-01

    There has been an increased emphasis on the quality of chest compressions as a part of the cardiopulmonary resuscitation (CPR) bundle of care for recent times. During CPR training, chest compression quality parameters can be measured directly from sensors within a manikin or from external devices placed on the manikin chest that use accelerometer-based technology. The aim of this study was to compare external chest compression data from the manikin-based Laerdal Skill Reporter (LSR) and the accelerometer-based Q-CPR technology, incorporated into the Philips MRx defibrillator, during CPR on a single Resusci Anne Simulator manikin. Each paramedic (n = 15) performed 2 sessions of 2 minutes of chest compressions, with a 2-minute rest period in between sessions. Both over-the-head and from-the-side positions were used on a single manikin. The quality of chest compressions were concurrently measured using both LSR and Philips MRx Q-CPR accelerometer with audiovisual feedback disabled. There was no significant difference in the measurement of the number of chest compressions performed in 2 minutes, the compression rate, total number of compressions of adequate depth, or the number of compressions exhibiting leaning between the LSR and the Phillips Q-CPR devices. There was a significant difference in measurement of compression depth (P < 0.0001) and duty cycle (P < 0.0001) with the MRx Q-CPR accelerometer demonstrating both lower compression depth and duty cycle compared with LSR. There was no significant difference in most chest compression quality metrics measured between the LSR and the Phillips Q-CPR devices when measured on a manikin. However, there were significant differences in the measurement of duty cycle and also the depth of compressions between the 2 devices with the Phillips Q-CPR device measuring lower depth of compression and duty cycle compared with the LSR device.

  8. The study of the effectiveness of chest compressions using the CPR-plus.

    PubMed

    Elding, C; Baskett, P; Hughes, A

    1998-03-01

    Effective cardiopulmonary resuscitation (CPR) requires a high level of skill from both healthcare professionals and the lay public. Inadequate chest compressions are a common cause of ineffective CPR. The CPR-plus is a non-invasive, hand-held, simple to use CPR adjunct designed to assist the rescuer to monitor and modify the compression technique during CPR, hopefully resulting in improved rescuer performance and more effective CPR. Forty qualified nurses were evaluated while they performed chest compressions on a training manikin. During simulated two-rescuer CPR (compression/ventilation ratio 5:1) the participants performed 150 compressions at a rate of 80-100 min. Compressions were performed with and without the CPR-plus and the results compared. The use of the CPR-plus was randomised with regard to whether the adjunct or the standard method was used first. The average number of correctly applied compressions was significantly better when the CPR-plus was used: 138.35/150 versus 110.70/150 (p = 0.0001). Improvements in techniques associated with the use of the CPR-plus also included a reduction in excessive application of pressure and incorrect hand position. The device provided reassurance of satisfactory compressions and an indication of impending fatigue in the rescuer.

  9. Open chest cardiac massage offers no benefit over closed chest compressions in patients with traumatic cardiac arrest.

    PubMed

    Bradley, Matthew J; Bonds, Brandon W; Chang, Luke; Yang, Shiming; Hu, Peter; Li, Hsiao-Chi; Brenner, Megan L; Scalea, Thomas M; Stein, Deborah M

    2016-11-01

    Open chest cardiac massage (OCCM) is a commonly performed procedure after traumatic cardiac arrest (TCA). OCCM has been reported to be superior to closed chest compressions (CCC) in animal models and in non-TCA. The purpose of this study is to prospectively compare OCCM versus CCC in TCA using end-tidal carbon dioxide (ETCO2), the criterion standard for determining the effectiveness of chest compressions and detection of return of spontaneous circulation (ROSC), as the surrogate for cardiac output and marker for adequacy of resuscitation. This prospective observational study enrolled patients over a 9-month period directly presenting to a level 1 trauma center after TCA. Continuous high-resolution ETCO2 measurements were collected every 6 seconds for periods of CCC and OCCM, respectively. Patients receiving CCC only were compared with patients receiving CCC followed by OCCM. Student's t tests were used to compare ETCO2 within and between groups. Thirty-three patients were enrolled (16 OCCM, 17 CCC-only). Mean time of CCC before OCCM was 66 seconds. Within the OCCM group, final, peak, mean, and median ETCO2 levels significantly increased when comparing the initial CCC period to the OCCM interval. Using a time-matched comparison, significant increases were observed in the final and peak but not mean and median values when comparing the first minute of CCC to the remaining time in the CCC-only group. However, when periods of OCCM were compared with equivalent periods of CCC-only, there were no differences in the initial, final, peak, mean, or median ETCO2 values. Correspondingly, no difference in rates of ROSC was observed between groups (OCCM 23.5% vs. CCC 38.9%; p = 0.53). Although we could not control for confounders, we found no significant improvement in ETCO2 or ROSC with OCCM. With newer endovascular techniques for aortic occlusion, thoracotomy solely for performing OCCM provides no benefit over CCC. Therapeutic study, level III.

  10. Improved recognition of ineffective chest compressions after a brief Crew Resource Management (CRM) training: a prospective, randomised simulation study.

    PubMed

    Haffner, Leopold; Mahling, Moritz; Muench, Alexander; Castan, Christoph; Schubert, Paul; Naumann, Aline; Reddersen, Silke; Herrmann-Werner, Anne; Reutershan, Jörg; Riessen, Reimer; Celebi, Nora

    2017-03-03

    Chest compressions are a core element of cardio-pulmonary resuscitation. Despite periodic training, real-life chest compressions have been reported to be overly shallow and/or fast, very likely affecting patient outcomes. We investigated the effect of a brief Crew Resource Management (CRM) training program on the correction rate of improperly executed chest compressions in a simulated cardiac arrest scenario. Final-year medical students (n = 57) were randomised to receive a 10-min computer-based CRM or a control training on ethics. Acting as team leaders, subjects performed resuscitation in a simulated cardiac arrest scenario before and after the training. Team members performed standardised overly shallow and fast chest compressions. We analysed how often the team leader recognised and corrected improper chest compressions, as well as communication and resuscitation quality. After the CRM training, team leaders corrected improper chest compressions (35.5%) significantly more often compared with those undergoing control training (7.7%, p = 0.03*). Consequently, four students have to be trained (number needed to treat = 3.6) for one improved chest compression scenario. Communication quality assessed by the Leader Behavior Description Questionnaire significantly increased in the intervention group by a mean of 4.5 compared with 2.0 (p = 0.01*) in the control group. A computer-based, 10-min CRM training improved the recognition of ineffective of chest compressions. Furthermore, communication quality increased. As guideline-adherent chest compressions have been linked to improved patient outcomes, our CRM training might represent a brief and affordable approach to increase chest compression quality and potentially improve patient outcomes.

  11. Detail view of steam chest and valve mechanisms for high ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view of steam chest and valve mechanisms for high pressure stage of unit 40. - Burnsville Natural Gas Pumping Station, Saratoga Avenue between Little Kanawha River & C&O Railroad line, Burnsville, Braxton County, WV

  12. Dominant hand position improves the quality of external chest compression: a manikin study based on 2010 CPR guidelines.

    PubMed

    Jiang, Cheng; Jiang, Shan; Zhao, Yan; Xu, Bing; Zhou, Xian-long

    2015-04-01

    The 2010 cardiopulmonary resuscitation (CPR) guidelines increased the importance of external chest compression. However, the best hand position to be the compressing one has not been identified. To investigate the effects of dominant or nondominant external chest compression hand position during CPR. Medical students performed five cycles of conventional CPR and completed one questionnaire. The CPR performances were manually evaluated, and detailed aspects of the external chest compression quality were assessed via the SimMan® Essential system (Laerdal China Ltd., Hangzhou, China). One hundred fifty-seven students participated in the nondominant hand (NH) group, and 68 students participated in the dominant hand (DH) group. The manual evaluations revealed no differences between the two groups. The proportion of chest compressions "above 100 cpm [compressions per minute]" was higher in the DH group than in the NH group (97% vs. 92%, respectively, p = 0.002). The frequency distributions of the chest compression rates were also significantly different between the two groups (p < 0.0001). The distribution of the NH group was concentrated within "130-139" cpm, whereas this distribution was concentrated within "140-149" cpm in the DH group. The chest compression depth of the DH group was deeper than that of the NH group (p = 0.001). The depth of the fifth cycle was significantly decreased compared with those of cycles 1, 2, and 3 in the NH group. A greater number of full chest recoils were observed in the NH group (p = 0.02). The dominant hand position during CPR was associated with a higher chest compression rate, a greater chest compression depth, and delayed fatigue. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Assessment of low-contrast detectability for compressed digital chest images

    NASA Astrophysics Data System (ADS)

    Cook, Larry T.; Insana, Michael F.; McFadden, Michael A.; Hall, Timothy J.; Cox, Glendon G.

    1994-04-01

    The ability of human observers to detect low-contrast targets in screen-film (SF) images, computed radiographic (CR) images, and compressed CR images was measured using contrast detail (CD) analysis. The results of these studies were used to design a two- alternative forced-choice (2AFC) experiment to investigate the detectability of nodules in adult chest radiographs. CD curves for a common screen-film system were compared with CR images compressed up to 125:1. Data from clinical chest exams were used to define a CD region of clinical interest that sufficiently challenged the observer. From that data, simulated lesions were introduced into 100 normal CR chest films, and forced-choice observer performance studies were performed. CR images were compressed using a full-frame discrete cosine transform (FDCT) technique, where the 2D Fourier space was divided into four areas of different quantization depending on the cumulative power spectrum (energy) of each image. The characteristic curve of the CR images was adjusted so that optical densities matched those of the SF system. The CD curves for SF and uncompressed CR systems were statistically equivalent. The slope of the CD curve for each was - 1.0 as predicted by the Rose model. There was a significant degradation in detection found for CR images compressed to 125:1. Furthermore, contrast-detail analysis demonstrated that many pulmonary nodules encountered in clinical practice are significantly above the average observer threshold for detection. We designed a 2AFC observer study using simulated 1-cm lesions introduced into normal CR chest radiographs. Detectability was reduced for all compressed CR radiographs.

  14. Initial defibrillation versus initial chest compression in a 4-minute ventricular fibrillation canine model of cardiac arrest.

    PubMed

    Wang, Yuan-Long; Zhong, Jing-Quan; Tao, Wen; Hou, Xue-Mei; Meng, Xiang-Lin; Zhang, Yun

    2009-07-01

    Previous laboratory and clinical studies have demonstrated that chest compression preceding defibrillation in prolonged ventricular fibrillation (VF) increases the likelihood of successful cardiac resuscitation. The lower limit of VF duration when preshock chest compression provides no benefit has not been specifically studied. We aimed to study the effect of order of defibrillation and chest compression on defibrillation and cardiac resuscitation in a 4-minute VF canine model of cardiac arrest. Prospective, randomized animal study. Key Laboratory of Cardiovascular Remodeling and Function Research and Department of Cardiology, QiLu Hospital. Twenty-four domestic dogs. VF was induced in anesthetized and ventilated canines. After 4 minutes of untreated VF, animals were randomly assigned to receive shock first or chest compression first. Animals in the shock-first group received an immediate single countershock of 360 J for <10 seconds, then 200 immediate compressions before pulse check or rhythm reanalysis. The ratio of compression to ventilation was 30:2. Interruptions to deliver rescue breaths were eliminated in this study. Animals in the chest compression-first group received 200 chest compressions before a single countershock; the other interventions were the same as for the shock-first group. End points were restoration of spontaneous circulation (ROSC), defined as spontaneous systolic arterial pressure >50 mm Hg, when epinephrine (0.02 mg/kg intravenously) was given, and resuscitation, defined as maintaining systolic arterial pressure >50 mm Hg at the 24-hour study end point. In the shock-first group, all animals achieved ROSC, and ten of 12 survived at the 24-hour study end point. In the chest compression-first group, 11 of 12 animals achieved ROSC, and nine of 12 survived at the 24-hour study end point. In this 4-minute VF canine model of cardiac arrest, the order of initial defibrillation or initial chest compression does not affect cardiac resuscitation.

  15. Helicopter-based in-water resuscitation with chest compressions: a pilot study.

    PubMed

    Winkler, Bernd E; Hartig, Frank; DuCanto, James; Koch, Andreas; Georgieff, Michael; Lungwitz, Yannick P; Muth, Claus-Martin

    2015-07-01

    Drowning is a relevant worldwide cause of severe disability and death. The delay of ventilations and chest compressions is a crucial problem in drowning victims. Hence, a novel helicopter-based ALS rescue concept with in-water ventilation and chest compressions was evaluated. Cardio pulmonary resuscitation (CPR) and vascular access were performed in a self-inflating Heliboat platform in an indoor wave pool using the Fastrach intubating laryngeal mask, the Oxylator resuscitator, Lund University Cardiopulmonary Assist System (LUCAS) chest compression device and EZ-IO intraosseous power drill. The time requirement and physical exertion on a Visual Analogue Scale (VAS) were compared between a procedure without waves and with moderate swell. Measurement of the elapsed time of the various stages of the procedure did not reveal significant differences between calm water and swell: Ventilation was initiated after 02:48 versus 03:02 and chest compression after 04:20 versus 04:18 min; the intraosseous cannulisation was completed after 05:59 versus 06:30 min after a simulated jump off the helicopter. The attachment of the LUCAS to the mannequin and the intraosseous cannulisation was rated significantly more demanding on the VAS during swell conditions. CPR appears to be possible when performed in a rescue platform with special equipment. The novel helicopter-based strategy appears to enable the rescuers to initiate CPR in an appropriate length of time and with an acceptable amount of physical exertion for the divers. The time for the helicopter to reach the patient will have to be very short to minimise neurological damage in the drowning victim. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  16. Impact of ventilation strategies during chest compression. An experimental study with clinical observations.

    PubMed

    Cordioli, Ricardo L; Lyazidi, Aissam; Rey, Nathalie; Granier, Jean-Max; Savary, Dominique; Brochard, Laurent; Richard, Jean-Christophe M

    2016-01-15

    The optimal ventilation strategy during cardiopulmonary resuscitation (CPR) is unknown. Chest compression (CC) generates circulation, while during decompression, thoracic recoil generates negative pressure and venous return. Continuous flow insufflation of oxygen (CFI) allows noninterrupted CC and generates positive airway pressure (Paw). The main objective of this study was to assess the effects of positive Paw compared with the current recommended ventilation strategy on intrathoracic pressure (P(IT)) variations, ventilation, and lung volume. In a mechanical model, allowing compression of the thorax below an equilibrium volume mimicking functional residual capacity (FRC), CC alone or with manual bag ventilation were compared with two levels of Paw with CFI. Lung volume change below FRC at the end of decompression and P(IT), as well as estimated alveolar ventilation, were measured during the bench study. Recordings were obtained in five cardiac arrest patients to confirm the bench findings. Lung volume was continuously below FRC, and as a consequence P(IT) remained negative during decompression in all situations, including with positive Paw. Compared with manual bag or CC alone, CFI with positive Paw limited the fall in lung volume and resulted in larger positive and negative P(IT) variations. Positive Paw with CFI significantly augmented ventilation induced by CC. Recordings in patients confirmed a major loss of lung volume below FRC during CPR, even with positive Paw. Compared with manual bag ventilation, positive Paw associated with CFI limits the loss in lung volume, enhances CC-induced positive P(IT), maintains negative P(IT) during decompression, and generates more alveolar ventilation.

  17. Irreversible JPEG compression of digital chest radiographs for primary interpretation: assessment of visually lossless threshold.

    PubMed

    Slone, Richard M; Muka, Edward; Pilgram, Thomas K

    2003-08-01

    To determine if digital chest images could be compressed in a primary interpretation context without perceived loss of fidelity (below the visually lossless threshold) at transilluminated film or cathode ray tube (CRT) display. One hundred forty-four posteroanterior radiographs were obtained with a digital chest radiography system. At both film and CRT display, an identified original image was presented side by side with a replicate, which was either an unaltered image or an image that had been Joint Photographic Experts Group (JPEG) compressed to 10:1, 20:1, or 50:1 and reconstructed. Each of the 10 readers indicated whether the replicate was "indistinguishable from the original" or "degraded" at clinical reading distance and at close inspection. The readers' ability to detect compressed images was examined for patterns; 95% CIs were used for statistical testing. With transilluminated film at clinical reading distance, readers were as likely to rate originals (48 [20%] of 240 readings) as degraded as they were to rate 20:1 replicates (106 [22%] of 480 readings) as degraded, but they frequently identified 50:1 replicates (283 [59%] of 480 readings) as degraded. At close inspection, 20:1 replicates (163 [34%] of 480 readings) were often identified as degraded, but 10:1 replicates (19 [8%] of 240 readings) were not identified as degraded more often than originals (17 [7%] of 240 readings). With CRT display, the results were nearly identical. At reading distance for primary interpretation, full-size digital chest radiographs that have been JPEG compressed to 10:1 or 20:1 and reconstructed are visually lossless at film or CRT display. Images compressed to 10:1 remain visually lossless at close inspection. Copyright RSNA, 2003.

  18. Chest physiotherapy--the mechanical approach to antiinfective therapy in cystic fibrosis.

    PubMed

    Zach, M S; Oberwaldner, B

    1987-01-01

    Chest physiotherapy is a treatment program that attempts to compensate for impaired mucociliary clearance. By removing mucopurulent secretions, it reduces airway obstruction and its consequences, such as atelectasis and hyperinflation; furthermore, physiotherapy can decrease the rate of proteolytic tissue damage by removing infected secretions. Conventional physiotherapy (clapping, vibration and compression, together with postural drainage and assisted coughing) is the most efficient physiotherapy for sick infants and young children. Later, mechanical chest percussion can reduce the patient's dependency on others. The forced expiration technique is another method of self-treatment, employing expiratory techniques to blow secretions out of the bronchi. Autogenic drainage, a special breathing technique, aims at avoiding airway compression by reducing positive expiratory transthoracic pressure. PEP-mask-physiotherapy achieves the same goal by expiring against an external airflow obstruction. Last but not least, physical exercise can clear the lungs of some CF patients and thus offers an attractive adjunct to physiotherapy.

  19. Ventilation distribution and chest wall mechanics in microgravity

    NASA Technical Reports Server (NTRS)

    Paiva, M.; Wantier, M.; Verbanck, S.; Engel, L. A.; Prisk, G. K.; Guy, H. J. B.; West, J. B.

    1997-01-01

    The effect of gravity on lung ventilation distribution and the mechanisms of the chest wall were investigated. The following tests were performed with the respiratory monitoring system of the Anthorack, flown onboard Spacelab D2 mission: single breath washout (SBW), multiple breath washout (MBW) and argon rebreathing (ARB). In order to study chest wall mechanisms in microgravity, a respiratory inductive plethysmograph was used. The SBW tests did not reach statistical significance, while the ARB tests showed that gravity independent inhomogeneity of specific ventilation is larger than gravity dependent inhomogeneity. In which concerns the chest wall mechanisms, the analysis on the four astronauts during the normal respirations of the relaxation maneuver showed a 40 percent increase on the abdominal contribution to respiration.

  20. Ventilation distribution and chest wall mechanics in microgravity

    NASA Technical Reports Server (NTRS)

    Paiva, M.; Wantier, M.; Verbanck, S.; Engel, L. A.; Prisk, G. K.; Guy, H. J. B.; West, J. B.

    1997-01-01

    The effect of gravity on lung ventilation distribution and the mechanisms of the chest wall were investigated. The following tests were performed with the respiratory monitoring system of the Anthorack, flown onboard Spacelab D2 mission: single breath washout (SBW), multiple breath washout (MBW) and argon rebreathing (ARB). In order to study chest wall mechanisms in microgravity, a respiratory inductive plethysmograph was used. The SBW tests did not reach statistical significance, while the ARB tests showed that gravity independent inhomogeneity of specific ventilation is larger than gravity dependent inhomogeneity. In which concerns the chest wall mechanisms, the analysis on the four astronauts during the normal respirations of the relaxation maneuver showed a 40 percent increase on the abdominal contribution to respiration.

  1. Association Between Chest Compression Interruptions and Clinical Outcomes of Ventricular Fibrillation Out-of-Hospital Cardiac Arrest.

    PubMed

    Brouwer, Tom F; Walker, Robert G; Chapman, Fred W; Koster, Rudolph W

    2015-09-15

    Minimizing pauses in chest compressions during cardiopulmonary resuscitation is a focus of current guidelines. Prior analyses found that prolonged pauses for defibrillation (perishock pauses) are associated with worse survival. We analyzed resuscitations to characterize the association between pauses for all reasons and both ventricular fibrillation termination and patient survival. In 319 patients with ventricular tachycardia/fibrillation out-of-hospital cardiac arrest, we analyzed recordings from all defibrillators used during resuscitation and measured durations of all cardiopulmonary resuscitation pauses. Median durations were 32 seconds (25th and 75th percentile, 22 and 52 seconds) for the longest pause for any reason, 23 seconds (25th and 75th percentile, 14 and 34 seconds) for the longest perishock pause, and 24 seconds (25th and 75th percentile, 11 and 38 seconds) for the longest nonshock pause. Multivariable regression models showed lower odds for survival per 5-second increase in the longest overall pause (odds ratio, 0.89; 95% confidence interval, 0.83-0.95), longest perishock pause (odds ratio, 0.85; 95% confidence interval, 0.77-0.93), and longest nonshock pause (odds ratio, 0.83; 95% confidence interval, 0.75-0.91). In 36% of cases, the longest pause was a nonshock pause; this subgroup had lower survival than the group in whom the longest pause was a perishock pause (27% versus 44%, respectively; P<0.01) despite a higher chest compression fraction. Preshock pauses were 8 seconds (25th and 75th percentile, 4 and 17 seconds) for shocks that terminated ventricular fibrillation and 7 seconds (25th and 75th percentile, 4 and 13 seconds) for shocks that did not (P=0.18). Prolonged pauses have a negative association with survival not explained by chest compression fraction or decreased ventricular fibrillation termination rate. Ventricular fibrillation termination was not the mechanism linking pause duration and survival. Strategies shortening the longest

  2. Importance of continuous chest compressions during cardiopulmonary resuscitation: improved outcome during a simulated single lay-rescuer scenario.

    PubMed

    Kern, Karl B; Hilwig, Ronald W; Berg, Robert A; Sanders, Arthur B; Ewy, Gordon A

    2002-02-05

    Interruptions to chest compression-generated blood flow during cardiopulmonary resuscitation (CPR) are detrimental. Data show that such interruptions for mouth-to-mouth ventilation require a period of "rebuilding" of coronary perfusion pressure to obtain the level achieved before the interruption. Whether such hemodynamic compromise from pausing to ventilate is enough to affect outcome is unknown. Thirty swine (weight 35 +/- 2 kg) underwent 3 minutes of untreated ventricular fibrillation before 12 minutes of basic life support CPR. Animals were randomized to receive either standard airway (A), breathing (B), and compression (C) CPR with expired-gas ventilation in a 15:2 compression-to-ventilation ratio or continuous chest compression CPR. Those randomized to the standard 15:2 group had no chest compressions for a period of 16 seconds each time the 2 ventilations were delivered. Defibrillation was attempted at 15 minutes of cardiac arrest. All resuscitated animals were supported in an intensive care environment for 1 hour, then in a maintenance facility for 24 hours. The primary end point of neurologically normal 24-hour survival was significantly better in the experimental group receiving continuous chest compression CPR (12 of 15 versus 2 of 15; P<0.0001). Mouth-to-mouth ventilation performed by single layperson rescuers produces substantial interruptions in chest compression-supported circulation. Continuous chest compression CPR produces greater neurologically normal 24-hour survival than standard ABC CPR when performed in a clinically realistic fashion. Any technique that minimizes lengthy interruptions of chest compressions during the first 10 to 15 minutes of basic life support should be given serious consideration in future efforts to improve outcome results from cardiac arrest.

  3. Quantization techniques for the compression of chest images by JPEG-type algorithms

    NASA Astrophysics Data System (ADS)

    Good, Walter F.; Gur, David

    1992-06-01

    The Joint Photographic Expert Group (JPEG) compression standard specifies a quantization procedure but does not specify a particular quantization table. In addition, there are quantization procedures which are effectively compatible with the standard but do not adhere to the simple quantization scheme described therein. These are important considerations, since it is the quantization procedure that primarily determines the compression ratio as well as the kind of information lost or artifacts introduced. A study has been conducted of issues related to the design of quantization techniques tailored for the compression of 12-bit chest images in radiology. Psycho-physical based quantization alone may not be optimal for images that are to be compressed and then used for primary diagnosis. Two specific examples of auxiliary techniques which can be used in conjunction with JPEG compression are presented here. In particular, preprocessing of the source image is shown to be advantageous under certain circumstances. In contrast, a proposed quantization technique in which isolated nonzero coefficients are removed has been shown to be generally detrimental. Image quality here is primarily measured by mean square error (MSE), although this study is in anticipation of more relevant reader performance studies of compression.

  4. Association of advanced airway device with chest compression fraction during out-of-hospital cardiopulmonary arrest.

    PubMed

    Kurz, Michael Christopher; Prince, David K; Christenson, James; Carlson, Jestin; Stub, Dion; Cheskes, Sheldon; Lin, Steve; Aziz, Michael; Austin, Michael; Vaillancourt, Christian; Colvin, Justin; Wang, Henry E

    2016-01-01

    Select Emergency Medical Services (EMS) practitioners substitute endotracheal intubation (ETI) with supraglottic airway (SGA) insertion to minimize CPR chest compression interruptions, but the resulting effects upon chest compression fraction (CCF) are unknown. We sought to determine the differences in CCF between adult out-of-hospital cardiac arrest (OHCA) receiving ETI and those receiving SGA. We studied adult, non-traumatic OHCA patients enrolled in the Resuscitation Outcomes Consortium (ROC) Prehospital Resuscitation using an Impedance valve and an Early vs. Delayed analysis (PRIMED) trial. Chest compressions were measured using compression or thoracic impedance sensors. We limited the analysis to those receiving ETI or SGA (Combitube, King Laryngeal Tube, or Laryngeal Mask Airway) and >2min of chest compression data before and after airway insertion. We compared CCF between ETI and SGA before and after airway insertion, adjusting for age, sex, witnessed arrest, bystander CPR, shockable initial rhythm, public location, PRIMED trial arm, and regional ROC center. We also compared the change in CCF for each airway technique. Of 14,955 patients enrolled in the ROC PRIMED trial, we analyzed 2767 cases, including 2051 ETI, 671 SGA, and 45 both. Among subjects in this investigation the mean age was 66.4 years with a male predominace, 46% with witnessed event, 37% receiving bystander CPR, and 22% presenting with an initially shockable rhythm. Pre- and post-airway CCF was higher for SGA than ETI (SGA pre-airway CCF 73.2% [95%CI: 71.6-74.7%] vs. ETI 70.6% [95%CI: 69.7-71.5%]; post-airway 76.7% [95%CI: 75.2-78.1%] vs. 72.4% [95%CI: 71.5-73.3%]). After adjusting for potential confounders, these significant changes persisted (pre-airway difference 2.2% favoring SGA, p-value=0.046; post-airway 3.4% favoring SGA, p=0.001). In patients with OHCA, we detected a slightly higher rate of CCF in patients for whom a SGA was inserted, both before and after insertion. However, the

  5. A New Chest Compression Depth Feedback Algorithm for High-Quality CPR Based on Smartphone

    PubMed Central

    Song, Yeongtak; Oh, Jaehoon

    2015-01-01

    Abstract Background Although many smartphone application (app) programs provide education and guidance for basic life support, they do not commonly provide feedback on the chest compression depth (CCD) and rate. The validation of its accuracy has not been reported to date. This study was a feasibility assessment of use of the smartphone as a CCD feedback device. In this study, we proposed the concept of a new real-time CCD estimation algorithm using a smartphone and evaluated the accuracy of the algorithm. Materials and Methods Using the double integration of the acceleration signal, which was obtained from the accelerometer in the smartphone, we estimated the CCD in real time. Based on its periodicity, we removed the bias error from the accelerometer. To evaluate this instrument's accuracy, we used a potentiometer as the reference depth measurement. The evaluation experiments included three levels of CCD (insufficient, adequate, and excessive) and four types of grasping orientations with various compression directions. We used the difference between the reference measurement and the estimated depth as the error. The error was calculated for each compression. Results When chest compressions were performed with adequate depth for the patient who was lying on a flat floor, the mean (standard deviation) of the errors was 1.43 (1.00) mm. When the patient was lying on an oblique floor, the mean (standard deviation) of the errors was 3.13 (1.88) mm. Conclusions The error of the CCD estimation was tolerable for the algorithm to be used in the smartphone-based CCD feedback app to compress more than 51 mm, which is the 2010 American Heart Association guideline. PMID:25402865

  6. A new chest compression depth feedback algorithm for high-quality CPR based on smartphone.

    PubMed

    Song, Yeongtak; Oh, Jaehoon; Chee, Youngjoon

    2015-01-01

    Although many smartphone application (app) programs provide education and guidance for basic life support, they do not commonly provide feedback on the chest compression depth (CCD) and rate. The validation of its accuracy has not been reported to date. This study was a feasibility assessment of use of the smartphone as a CCD feedback device. In this study, we proposed the concept of a new real-time CCD estimation algorithm using a smartphone and evaluated the accuracy of the algorithm. Using the double integration of the acceleration signal, which was obtained from the accelerometer in the smartphone, we estimated the CCD in real time. Based on its periodicity, we removed the bias error from the accelerometer. To evaluate this instrument's accuracy, we used a potentiometer as the reference depth measurement. The evaluation experiments included three levels of CCD (insufficient, adequate, and excessive) and four types of grasping orientations with various compression directions. We used the difference between the reference measurement and the estimated depth as the error. The error was calculated for each compression. When chest compressions were performed with adequate depth for the patient who was lying on a flat floor, the mean (standard deviation) of the errors was 1.43 (1.00) mm. When the patient was lying on an oblique floor, the mean (standard deviation) of the errors was 3.13 (1.88) mm. The error of the CCD estimation was tolerable for the algorithm to be used in the smartphone-based CCD feedback app to compress more than 51 mm, which is the 2010 American Heart Association guideline.

  7. Measurement and control for mechanical compressive stress

    NASA Astrophysics Data System (ADS)

    Li, Qing; Ye, Guang; Pan, Lan; Wu, Xiushan

    2001-12-01

    At present, the indirect method is applied to measuring and controlling mechanical compressive stress, which is the measurement and control of rotating torque of screw with torque transducer during screw revolving. Because the friction coefficient between every screw-cap and washer, of screw-thread is different, the compressive stress of every screw may is different when the machinery is equipped. Therefore, the accurate measurement and control of mechanical compressive stress is realized by the direct measurement of mechanical compressive stress. The author introduces the research of contrast between compressive stress and rotating torque in the paper. The structure and work principle of a special washer type transducer is discussed emphatically. The special instrument cooperates with the washer type transducer for measuring and controlling mechanical compressive stress. The control tactics based on the rate of compressive stress is put to realize accurate control of mechanical compressive stress.

  8. A Feasibility Study for Measuring Accurate Chest Compression Depth and Rate on Soft Surfaces Using Two Accelerometers and Spectral Analysis

    PubMed Central

    Gutiérrez, J. J.; Russell, James K.

    2016-01-01

    Background. Cardiopulmonary resuscitation (CPR) feedback devices are being increasingly used. However, current accelerometer-based devices overestimate chest displacement when CPR is performed on soft surfaces, which may lead to insufficient compression depth. Aim. To assess the performance of a new algorithm for measuring compression depth and rate based on two accelerometers in a simulated resuscitation scenario. Materials and Methods. Compressions were provided to a manikin on two mattresses, foam and sprung, with and without a backboard. One accelerometer was placed on the chest and the second at the manikin's back. Chest displacement and mattress displacement were calculated from the spectral analysis of the corresponding acceleration every 2 seconds and subtracted to compute the actual sternal-spinal displacement. Compression rate was obtained from the chest acceleration. Results. Median unsigned error in depth was 2.1 mm (4.4%). Error was 2.4 mm in the foam and 1.7 mm in the sprung mattress (p < 0.001). Error was 3.1/2.0 mm and 1.8/1.6 mm with/without backboard for foam and sprung, respectively (p < 0.001). Median error in rate was 0.9 cpm (1.0%), with no significant differences between test conditions. Conclusion. The system provided accurate feedback on chest compression depth and rate on soft surfaces. Our solution compensated mattress displacement, avoiding overestimation of compression depth when CPR is performed on soft surfaces. PMID:27999808

  9. A Feasibility Study for Measuring Accurate Chest Compression Depth and Rate on Soft Surfaces Using Two Accelerometers and Spectral Analysis.

    PubMed

    Ruiz de Gauna, Sofía; González-Otero, Digna M; Ruiz, Jesus; Gutiérrez, J J; Russell, James K

    2016-01-01

    Background. Cardiopulmonary resuscitation (CPR) feedback devices are being increasingly used. However, current accelerometer-based devices overestimate chest displacement when CPR is performed on soft surfaces, which may lead to insufficient compression depth. Aim. To assess the performance of a new algorithm for measuring compression depth and rate based on two accelerometers in a simulated resuscitation scenario. Materials and Methods. Compressions were provided to a manikin on two mattresses, foam and sprung, with and without a backboard. One accelerometer was placed on the chest and the second at the manikin's back. Chest displacement and mattress displacement were calculated from the spectral analysis of the corresponding acceleration every 2 seconds and subtracted to compute the actual sternal-spinal displacement. Compression rate was obtained from the chest acceleration. Results. Median unsigned error in depth was 2.1 mm (4.4%). Error was 2.4 mm in the foam and 1.7 mm in the sprung mattress (p < 0.001). Error was 3.1/2.0 mm and 1.8/1.6 mm with/without backboard for foam and sprung, respectively (p < 0.001). Median error in rate was 0.9 cpm (1.0%), with no significant differences between test conditions. Conclusion. The system provided accurate feedback on chest compression depth and rate on soft surfaces. Our solution compensated mattress displacement, avoiding overestimation of compression depth when CPR is performed on soft surfaces.

  10. Effectiveness of feedback with a smartwatch for high-quality chest compressions during adult cardiac arrest: A randomized controlled simulation study

    PubMed Central

    Song, Yeongtak; Chee, Youngjoon; Lim, Tae Ho; Kang, Hyunggoo; Shin, Hyungoo

    2017-01-01

    Previous studies have demonstrated the potential for using smartwatches with a built-in accelerometer as feedback devices for high-quality chest compression during cardiopulmonary resuscitation. However, to the best of our knowledge, no previous study has reported the effects of this feedback on chest compressions in action. A randomized, parallel controlled study of 40 senior medical students was conducted to examine the effect of chest compression feedback via a smartwatch during cardiopulmonary resuscitation of manikins. A feedback application was developed for the smartwatch, in which visual feedback was provided for chest compression depth and rate. Vibrations from smartwatch were used to indicate the chest compression rate. The participants were randomly allocated to the intervention and control groups, and they performed chest compressions on manikins for 2 min continuously with or without feedback, respectively. The proportion of accurate chest compression depth (≥5 cm and ≤6 cm) was assessed as the primary outcome, and the chest compression depth, chest compression rate, and the proportion of complete chest decompression (≤1 cm of residual leaning) were recorded as secondary outcomes. The proportion of accurate chest compression depth in the intervention group was significantly higher than that in the control group (64.6±7.8% versus 43.1±28.3%; p = 0.02). The mean compression depth and rate and the proportion of complete chest decompressions did not differ significantly between the two groups (all p>0.05). Cardiopulmonary resuscitation-related feedback via a smartwatch could provide assistance with respect to the ideal range of chest compression depth, and this can easily be applied to patients with out-of-hospital arrest by rescuers who wear smartwatches. PMID:28369055

  11. Effectiveness of feedback with a smartwatch for high-quality chest compressions during adult cardiac arrest: A randomized controlled simulation study.

    PubMed

    Ahn, Chiwon; Lee, Juncheol; Oh, Jaehoon; Song, Yeongtak; Chee, Youngjoon; Lim, Tae Ho; Kang, Hyunggoo; Shin, Hyungoo

    2017-01-01

    Previous studies have demonstrated the potential for using smartwatches with a built-in accelerometer as feedback devices for high-quality chest compression during cardiopulmonary resuscitation. However, to the best of our knowledge, no previous study has reported the effects of this feedback on chest compressions in action. A randomized, parallel controlled study of 40 senior medical students was conducted to examine the effect of chest compression feedback via a smartwatch during cardiopulmonary resuscitation of manikins. A feedback application was developed for the smartwatch, in which visual feedback was provided for chest compression depth and rate. Vibrations from smartwatch were used to indicate the chest compression rate. The participants were randomly allocated to the intervention and control groups, and they performed chest compressions on manikins for 2 min continuously with or without feedback, respectively. The proportion of accurate chest compression depth (≥5 cm and ≤6 cm) was assessed as the primary outcome, and the chest compression depth, chest compression rate, and the proportion of complete chest decompression (≤1 cm of residual leaning) were recorded as secondary outcomes. The proportion of accurate chest compression depth in the intervention group was significantly higher than that in the control group (64.6±7.8% versus 43.1±28.3%; p = 0.02). The mean compression depth and rate and the proportion of complete chest decompressions did not differ significantly between the two groups (all p>0.05). Cardiopulmonary resuscitation-related feedback via a smartwatch could provide assistance with respect to the ideal range of chest compression depth, and this can easily be applied to patients with out-of-hospital arrest by rescuers who wear smartwatches.

  12. Chest compression duration influences outcome between integrated load-distributing band and manual CPR during cardiac arrest.

    PubMed

    Olsen, J-A; Lerner, E B; Persse, D; Sterz, F; Lozano, M; Brouwer, M A; Westfall, M; van Grunsven, P M; Travis, D T; Herken, U R; Brunborg, C; Wik, L

    2016-02-01

    The Circulation Improving Resuscitation Care (CIRC) Trial found equivalent survival in adult out-of-hospital cardiac arrest (OHCA) patients who received integrated load-distributing band CPR (iA-CPR) compared to manual CPR (M-CPR). We hypothesized that as chest compression duration increased, iA-CPR provided a survival benefit when compared to M-CPR. A pre-planned secondary analysis of OHCA of presumed cardiac etiology from the randomized CIRC trial. Chest compressions duration was defined as the total number of minutes spent on compressions during resuscitation and identified from transthoracic impedance and accelerometer data recorded by the EMS defibrillator. Logistic regression was used to model the interaction between treatment and duration of chest compressions and was covariate-adjusted for trial site, patient age, witnessed arrest, and initial shockable rhythm. Primary outcome was survival to hospital discharge. We enrolled 4231 subjects and of those, 2012 iA-CPR and 2002 M-CPR had complete outcome and duration of chest compressions data. While covariate-adjusted odds ratio for survival to hospital discharge was 1.86 in favor of iA-CPR (95% CI 1.16-3.0), there was an interaction between duration and study arm. When this was factored into the multivariate equation, the odds ratio for survival to hospital discharge showed a significant benefit for iA-CPR vs. M-CPR for chest compression duration greater than 16.5 min. After adjusting for compression duration and duration-treatment interaction, iA-CPR showed a significant benefit for survival to hospital discharge vs. M-CPR in patients with OHCA if chest compression duration was longer than 16.5 min. © 2015 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  13. Optimal Chest Compression Rate and Compression to Ventilation Ratio in Delivery Room Resuscitation: Evidence from Newborn Piglets and Neonatal Manikins

    PubMed Central

    Solevåg, Anne Lee; Schmölzer, Georg M.

    2017-01-01

    Cardiopulmonary resuscitation (CPR) duration until return of spontaneous circulation (ROSC) influences survival and neurologic outcomes after delivery room (DR) CPR. High quality chest compressions (CC) improve cerebral and myocardial perfusion. Improved myocardial perfusion increases the likelihood of a faster ROSC. Thus, optimizing CC quality may improve outcomes both by preserving cerebral blood flow during CPR and by reducing the recovery time. CC quality is determined by rate, CC to ventilation (C:V) ratio, and applied force, which are influenced by the CC provider. Thus, provider performance should be taken into account. Neonatal resuscitation guidelines recommend a 3:1 C:V ratio. CCs should be delivered at a rate of 90/min synchronized with ventilations at a rate of 30/min to achieve a total of 120 events/min. Despite a lack of scientific evidence supporting this, the investigation of alternative CC interventions in human neonates is ethically challenging. Also, the infrequent occurrence of extensive CPR measures in the DR make randomized controlled trials difficult to perform. Thus, many biomechanical aspects of CC have been investigated in animal and manikin models. Despite mathematical and physiological rationales that higher rates and uninterrupted CC improve CPR hemodynamics, studies indicate that provider fatigue is more pronounced when CC are performed continuously compared to when a pause is inserted after every third CC as currently recommended. A higher rate (e.g., 120/min) is also more fatiguing, which affects CC quality. In post-transitional piglets with asphyxia-induced cardiac arrest, there was no benefit of performing continuous CC at a rate of 90/min. Not only rate but duty cycle, i.e., the duration of CC/total cycle time, is a known determinant of CC effectiveness. However, duty cycle cannot be controlled with manual CC. Mechanical/automated CC in neonatal CPR has not been explored, and feedback systems are under-investigated in this

  14. Retention of basic life support knowledge, self-efficacy and chest compression performance in Thai undergraduate nursing students.

    PubMed

    Partiprajak, Suphamas; Thongpo, Pichaya

    2016-01-01

    This study explored the retention of basic life support knowledge, self-efficacy, and chest compression performance among Thai nursing students at a university in Thailand. A one-group, pre-test and post-test design time series was used. Participants were 30 nursing students undertaking basic life support training as a care provider. Repeated measure analysis of variance was used to test the retention of knowledge and self-efficacy between pre-test, immediate post-test, and re-test after 3 months. A Wilcoxon signed-rank test was used to compare the difference in chest compression performance two times. Basic life support knowledge was measured using the Basic Life Support Standard Test for Cognitive Knowledge. Self-efficacy was measured using the Basic Life Support Self-Efficacy Questionnaire. Chest compression performance was evaluated using a data printout from Resusci Anne and Laerdal skillmeter within two cycles. The training had an immediate significant effect on the knowledge, self-efficacy, and skill of chest compression; however, the knowledge and self-efficacy significantly declined after post-training for 3 months. Chest compression performance after training for 3 months was positively retaining compared to the first post-test but was not significant. Therefore, a retraining program to maintain knowledge and self-efficacy for a longer period of time should be established after post-training for 3 months. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Chest compression with kneeling posture in hospital cardiopulmonary resuscitation: A randomised crossover simulation study.

    PubMed

    Oh, Jaehoon; Chee, Youngjoon; Lim, Taeho; Cho, Youngsuk; Kim, In Young

    2014-12-01

    We suggest an alternative chest compression (CC) in kneeling posture using a 'kneeling stool' on which the performer kneels beside the patient on a bed in-hospital. In kneeling posture, we can maintain high quality cardiopulmonary resuscitation (CPR) without the bed height adjustment, which is necessary and inconvenient in standing posture. This study is a randomised crossover trial with 38 participants working in one ED. The first group knelt on the kneeling stool beside a manikin placed on a bed, whereas the second group stood on a step stool with the manikin at knee level using bed height adjustment. All the participants performed continuous chest compression for 5 min without audio-visual feedback. After that, the posture was changed in each group. The parameters of CC quality (CC depth, rate, accuracy, and incomplete chest recoil), visual analogue scale (VAS) for fatigue and pain, and preference of participants were compared between the two groups. The data of 33 participants in both postures were analysed following exclusion of five participants. In the comparisons overall and per minute between the two postures, the parameters and VAS do not differ significantly (all P > 0.05) except for the median 1st CC rate that was faster in kneeling posture than in standing posture, P = 0.01). Twenty-three performers preferred the kneeling posture. A kneeling posture with a kneeling stool were preferred by participants, which have shown similar results in CC parameters and VAS with a standing posture on a stepstool with bed height adjustment during in-hospital CPR. © 2014 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

  16. New visual feedback device improves performance of chest compressions by professionals in simulated cardiac arrest.

    PubMed

    Skorning, Max; Beckers, Stefan K; Brokmann, Jörg Ch; Rörtgen, Daniel; Bergrath, Sebastian; Veiser, Thomas; Heussen, Nicole; Rossaint, Rolf

    2010-01-01

    Quality of external chest compression (ECC) is a key component of Basic Life Support. Different approaches to improve rescuers' performance have been evaluated, but few attempts have been made to invent simple devices to improve performance. This study evaluates a new visual feedback system for ECC for healthcare professionals. Ninety-three healthcare professionals volunteered (14 emergency medical technicians, 45 paramedics, 34 physicians; age 32+/-7.2 (range 21-61); 72% male) in this randomized cross-over study. All subjects were tested on a manikin (Skillreporter ResusciAnne, Laerdal, Stavanger, Norway) in identical mock cardiac arrest scenario and asked to perform 2 min of continuous ECC (secured airway): Group A (n=46): ECC with device first, followed by ECC without device a minimum of 45 min later; group B (n=47): vice versa. Primary endpoints: mean compression rate 90-120 min(-1); mean compression depth 38-51 mm. Data were analyzed using repeated measure logistic regression model for binary categorized endpoints and repeated measure ANOVA test for continuous endpoints. Correct compression depth was achieved by 45.2% of subjects (95%-CI: 30.5-64.9 mm) without vs. 73.1% (95%-CI: 40.3-57.4 mm) with device (p<0.001); correct compression rate was achieved by 62.4% (95%-CI: 78-147.8 min(-1)) without vs. 94.6% (95%-CI: 87.3-126.6 min(-1)) with device (p<0.001). Overall, 85% of the subjects thought the feedback system was helpful and 80.6% would use it if available. The new visual feedback device significantly improved ECC performance (compression rate and depth) by healthcare professionals in simulated cardiac arrest. Most participants found the device easy to use. Copyright 2009 Elsevier Ireland Ltd. All rights reserved.

  17. Eccentric crank variable compression ratio mechanism

    DOEpatents

    Lawrence, Keith Edward; Moser, William Elliott; Roozenboom, Stephan Donald; Knox, Kevin Jay

    2008-05-13

    A variable compression ratio mechanism for an internal combustion engine that has an engine block and a crankshaft is disclosed. The variable compression ratio mechanism has a plurality of eccentric disks configured to support the crankshaft. Each of the plurality of eccentric disks has at least one cylindrical portion annularly surrounded by the engine block. The variable compression ratio mechanism also has at least one actuator configured to rotate the plurality of eccentric disks.

  18. Chest Compression Injuries Detected via Routine Post-arrest Care in Patients Who Survive to Admission after Out-of-hospital Cardiac Arrest.

    PubMed

    Boland, Lori L; Satterlee, Paul A; Hokanson, Jonathan S; Strauss, Craig E; Yost, Dana

    2015-01-01

    Abstract Objective. To examine injuries produced by chest compressions in out-of-hospital cardiac arrest (OHCA) patients who survive to hospital admission. Methods. A retrospective cohort study was conducted among 235 consecutive patients who were hospitalized after nontraumatic OHCA in Minnesota between January 2009 and May 2012 (117 survived to discharge; 118 died during hospitalization). Cases were eligible if the patient had received prehospital compressions from an emergency medical services (EMS) provider. One EMS provider in the area was using a mechanical compression device (LUCAS(TM)) as standard equipment, so the association between injury and use of mechanical compression was also examined. Prehospital care information was abstracted from EMS run sheets, and hospital records were reviewed for injuries documented during the post-arrest hospitalization that likely resulted from compressions. Results. Injuries were identified in 31 patients (13%), the most common being rib fracture (9%) and intrathoracic hemorrhage (3%). Among those who survived to discharge, the mean length of stay was not statistically significantly different between those with injuries (13.5 days) and those without (10.8 days; p = 0.23). Crude injury prevalence was higher in those who died prior to discharge, had received compressions for >10 minutes (versus ≤10 minutes) and underwent computer tomography (CT) imaging, but did not differ by bystander compressions or use of mechanical compression. After multivariable adjustment, only compression time > 10 min and CT imaging during hospitalization were positively associated with detected injury (OR = 7.86 [95% CI = 1.7-35.9] and 6.30 [95% CI = 2.6-15.5], respectively). Conclusion. In patients who survived OHCA to admission, longer duration of compressions and use of CT during the post-arrest course were associated positively with documented compression injury. Compression-induced injuries detected via routine post-arrest care are

  19. Accurate measurement of chest compression depth using impulse-radio ultra-wideband sensor on a mattress

    PubMed Central

    Kim, Yeomyung

    2017-01-01

    Objective We developed a new chest compression depth (CCD) measuring technology using radar and impulse-radio ultra-wideband (IR-UWB) sensor. This study was performed to determine its accuracy on a soft surface. Methods Four trials, trial 1: chest compressions on the floor using an accelerometer device; trial 2: chest compressions on the floor using an IR-UWB sensor; trial 3: chest compressions on a foam mattress using an accelerometer device; trial 4: chest compressions on a foam mattress using an IR-UWB sensor, were performed in a random order. In all the trials, a cardiopulmonary resuscitation provider delivered 50 uninterrupted chest compressions to a manikin. Results The CCD measured by the manikin and the device were as follows: 57.42 ± 2.23 and 53.92 ± 2.92 mm, respectively in trial 1 (p < 0.001); 56.29 ± 1.96 and 54.16 ± 3.90 mm, respectively in trial 2 (p < 0.001); 55.61 ± 1.57 and 103.48 ± 10.48 mm, respectively in trial 3 (p < 0.001); 57.14 ± 3.99 and 55.51 ± 3.39 mm, respectively in trial 4 (p = 0.012). The gaps between the CCD measured by the manikin and the devices (accelerometer device vs. IR-UWB sensor) on the floor were not different (3.50 ± 2.08 mm vs. 3.15 ± 2.27 mm, respectively, p = 0.136). However, the gaps were significantly different on the foam mattress (48.53 ± 5.65 mm vs. 4.10 ± 2.47 mm, p < 0.001). Conclusion The IR-UWB sensor could measure the CCD accurately both on the floor and on the foam mattress. PMID:28854262

  20. Short-Term Effects of High-Frequency Chest Compression and Positive Expiratory Pressure in Patients With Cystic Fibrosis

    PubMed Central

    Fainardi, Valentina; Longo, Francesco; Faverzani, Silvia; Tripodi, Maria Candida; Chetta, Alfredo; Pisi, Giovanna

    2011-01-01

    Background Cystic fibrosis patients require daily airway clearance therapies. The primary objective of this study was to compare the short-term efficacy of high-frequency chest compression and positive expiratory pressure mask on expectorated sputum, pulmonary function, and oxygen saturation in patients with CF hospitalized for an acute pulmonary exacerbation. Methods A controlled randomized cross-over trial with 24 hours between treatments was used. Thirty-four CF patients (26 ± 6.5 years) were included in the study. Before and 30 minutes after each treatment were recorded: pulmonary function testing, oxygen saturation, and perceived dyspnea. Preference for the two devices was assessed. Results No statistically significant difference between high-frequency chest compression and positive expiratory pressure mask was found in sputum production and in lung function testing. A reduction in SpO2 was found after positive expiratory pressure mask (98 ± 1.0% versus 97 ± 1.2%; P < 0.001). Both treatments induced a statistically significant increase in Borg scale for dyspnea without differences between them. Patients reported greater satisfaction with positive expiratory pressure mask than with high-frequency chest compression (P < 0.001). Conclusion High-frequency chest compression and positive expiratory pressure mask have comparable short-term effects on expectorated sputum and lung function. Although positive expiratory pressure mask was associated with a lower SpO2, it was better tolerated than high-frequency chest compression. Keywords Airway clearance therapies; High-frequency chest compression; Sputum; Cystic fibrosis PMID:22393338

  1. Hands-off Time during Automated Chest Compression Device Application in Out-of-Hospital Cardiac Arrest: A Case Series Report.

    PubMed

    Maurin, Olga; Frattini, Benoit; Jost, Daniel; Galinou, Noémie; Alhanati, Laure; Dang Minh, Pascal; Genotelle, Nicolas; Burlaton, Guillaume; de Regloix, Stanislas; Bignand, Michel; Tourtier, Jean Pierre

    2016-01-01

    During out-of-hospital cardiac arrest (OHCA), chest compression interruptions or hands-off time (HOT) affect the prognosis. Our aim was to measure HOT due to the application of an automated chest compression device (ACD) by an advanced life support team. This was a prospective observational case series report since the introduction of a new method of installing the ACD. Inclusion criteria were patients over 18 years old with OHCA who were treated with an ACD (Lucas 2(TM), Physio-Control). The ACD application was indicated only for OHCA patients transported to a hospital for Extra Corporeal Life Support (ECLS). We recorded the HOT related to switching from manual to mechanical chest compressions. An ACD consists of dorsal and ventral components, which can be installed either in one or in two steps, separated from a chest compression sequence. HOT was expressed as a median number of seconds [interquartile range]. From January 1, 2012 to January 15, 2013, 30 patients were included. In the case of ACD application in one phase (n = 16), the median HOT was 25.3 s [19.8-30.5]. With regard to patients with an ACD application in two phases (n = 14), the median HOT was, respectively, 9.8 s [7.8-17] and 12.4 s [9.5-16.2], that is, a median global HOT of 23.6 s [19-27.6]. HOT was not different between ACD applications in one or two phases (p = 0.52). For a two phase application, the median chest compression time between the two manipulations was 14.2 s [6.4-18]. There was no significant difference between techniques in the application of the Lucas 2(TM) device in terms of HOT. The short time needed to apply the device lends itself well to use as a primary chest compression modality during cardiac arrest as well as a bridge to novel resuscitation strategies (ECLS). A further study is currently underway with a larger number of ECLS patients.

  2. Chest compression quality, exercise intensity, and energy expenditure during cardiopulmonary resuscitation using compression-to-ventilation ratios of 15:1 or 30:2 or chest compression only: a randomized, crossover manikin study

    PubMed Central

    Kwak, Se-Jung; Kim, Young-Min; Baek, Hee Jin; Kim, Se Hong; Yim, Hyeon Woo

    2016-01-01

    Objective Our aim was to compare the compression quality, exercise intensity, and energy expenditure in 5-minute single-rescuer cardiopulmonary resuscitation (CPR) using 15:1 or 30:2 compression-to-ventilation (C:V) ratios or chest compression only (CCO). Methods This was a randomized, crossover manikin study. Medical students were randomized to perform either type of CPR and do the others with intervals of at least 1 day. We measured compression quality, ratings of perceived exertion (RPE) score, heart rate, maximal oxygen uptake, and energy expenditure during CPR. Results Forty-seven students were recruited. Mean compression rates did not differ between the 3 groups. However, the mean percentage of adequate compressions in the CCO group was significantly lower than that of the 15:1 or 30:2 group (31.2±30.3% vs. 55.1±37.5% vs. 54.0±36.9%, respectively; P<0.001) and the difference occurred within the first minute. The RPE score in each minute and heart rate change in the CCO group was significantly higher than those of the C:V ratio groups. There was no significant difference in maximal oxygen uptake between the 3 groups. Energy expenditure in the CCO group was relatively lower than that of the 2 C:V ratio groups. Conclusion CPR using a 15:1 C:V ratio may provide a compression quality and exercise intensity comparable to those obtained using a 30:2 C:V ratio. An earlier decrease in compression quality and increase in RPE and heart rate could be produced by CCO CPR compared with 15:1 or 30:2 C:V ratios with relatively lower oxygen uptake and energy expenditure. PMID:27752633

  3. Chest compression quality, exercise intensity, and energy expenditure during cardiopulmonary resuscitation using compression-to-ventilation ratios of 15:1 or 30:2 or chest compression only: a randomized, crossover manikin study.

    PubMed

    Kwak, Se-Jung; Kim, Young-Min; Baek, Hee Jin; Kim, Se Hong; Yim, Hyeon Woo

    2016-09-01

    Our aim was to compare the compression quality, exercise intensity, and energy expenditure in 5-minute single-rescuer cardiopulmonary resuscitation (CPR) using 15:1 or 30:2 compression-to-ventilation (C:V) ratios or chest compression only (CCO). This was a randomized, crossover manikin study. Medical students were randomized to perform either type of CPR and do the others with intervals of at least 1 day. We measured compression quality, ratings of perceived exertion (RPE) score, heart rate, maximal oxygen uptake, and energy expenditure during CPR. Forty-seven students were recruited. Mean compression rates did not differ between the 3 groups. However, the mean percentage of adequate compressions in the CCO group was significantly lower than that of the 15:1 or 30:2 group (31.2±30.3% vs. 55.1±37.5% vs. 54.0±36.9%, respectively; P<0.001) and the difference occurred within the first minute. The RPE score in each minute and heart rate change in the CCO group was significantly higher than those of the C:V ratio groups. There was no significant difference in maximal oxygen uptake between the 3 groups. Energy expenditure in the CCO group was relatively lower than that of the 2 C:V ratio groups. CPR using a 15:1 C:V ratio may provide a compression quality and exercise intensity comparable to those obtained using a 30:2 C:V ratio. An earlier decrease in compression quality and increase in RPE and heart rate could be produced by CCO CPR compared with 15:1 or 30:2 C:V ratios with relatively lower oxygen uptake and energy expenditure.

  4. Comparison of Methods for the Determination of Cardiopulmonary Resuscitation Chest Compression Fraction

    PubMed Central

    Iyanaga, Masayuki; Gray, Randal; Stephens, Shannon W.; Akinsanya, Olajide; Rodgers, Joel; Smyrski, Kathleen; Wang, Henry E.

    2012-01-01

    Objective While cardiopulmonary resuscitation (CPR) chest compression fraction (CCF) is associated with out-of-hospital cardiac arrest (OHCA) outcomes, there is no standard method for the determination of CCF. We compared nine methods for calculating CCF. Methods We studied consecutive adult OHCA patients treated by Alabama Emergency Medical Services (EMS) agencies of the Resuscitation Outcomes Consortium (ROC) during Jan. 1, 2010 - Oct. 28, 2010. Paramedics used portable cardiac monitors with real-time chest compression detection technology (LifePak 12, Physio-Control, Redmond, Washington). We performed both automated CCF calculation for the entire care episode as well as manual review of CPR data in 1-minute epochs, defining CCF as the proportion of each treatment interval with active chest compressions. We compared the CCF values resulting from 9 calculation methods: 1) mean CCF for the entire patient care episode (automated calculation by manufacturer software), 2) mean CCF for first 3 minutes of patient care, 3) mean CCF for first 5 minutes, 4) mean CCF for first 10 minutes, 5) mean CCF for the entire episode except first 5 minutes, 6) mean CCF for last 5 minutes, 7) mean CCF from start to first shock, 8) mean CCF for the first half of resuscitation, 9) mean CCF for the second half of resuscitation. We compared CCF for Methods 2-9 with Method 1 using paired t-tests with a Bonferroni-adjusted p-value of 0.006 (99.5% confidence intervals). Results Among 102 adult OHCA, patient demographics were: mean age 60.3 years (SD 20.8 years), African American 56.9%, male 63.7%, and shockable ECG rhythm 23.5%. Mean CPR duration was 728 seconds (95% CI: 647-809 seconds). Mean CCF for the 9 CCF calculation methods were: 1) 0.587; 2) 0.526; 3) 0.541; 4) 0.566; 5) 0.562; 6) 0.597; 7) 0.530; 8) 0.550; 9) 0.590%. Compared with Method 1, Method 7 CCF (start to first shock) was slightly lower (−0.057; 99.5% CI: −0.100 – (−0.014)). There were no other statistically

  5. Degree of exercise intensity during continuous chest compression in upper-body-trained individuals.

    PubMed

    Ogata, Hisayoshi; Fujimaru, Ikuyo; Kondo, Takaharu

    2015-12-19

    Although chest-compression-only cardiopulmonary resuscitation (CCO-CPR) is recommended for lay bystanders, fatigue is easily produced during CCO-CPR. If CCO-CPR can be performed at a lower intensity of exercise, higher resistance to fatigue is expected. Since chest compression is considered to be a submaximal upper body exercise in a steady rhythm and since the unit of load for chest compression is expressed as work rate, we investigated the possibility that peak work rate of the upper body determines the level of exercise intensity during CCO-CPR. Twelve sedentary individuals (group Se), 11 rugby players (group R), and 11 swimmers (group Sw) performed 10-min CCO-CPR, and heart rate (HR) and rating of perceived exertion (RPE) were measured as indices of exercise intensity. Multiple linear regression analysis was carried out to assess potential relationships of upper body weight, peak lumbar extension force, peak work rate, and peak oxygen uptake recorded during arm-crank exercise with HR and RPE during CCO-CPR. Values of peak work rate during arm-crank exercise (Peak WR-AC) in group Se, group R, and group Sw were 108 ± 12, 139 ± 27, and 146 ± 24 watts, respectively. Values of the latter two groups were significantly higher than the value of group Se (group R, P < 0.01; group Sw, P < 0.001). HR during CCO-CPR increased with time, reaching 127.8 ± 17.6, 114.8 ± 16.5, and 118.1 ± 14.2 bpm at the 10th minute in group Se, group R, and group Sw, respectively. On the other hand, RPE during CCO-CPR increased with time, reaching 16.4 ± 1.4, 15.4 ± 1.7, and 13.9 ± 2.2 at the 10th minute in group Se, group R, and group Sw, respectively. Multiple linear regression analysis showed that only peak WR-AC affects both HR and RPE at the 10th minute of CCO-CPR (HR, r = -0.458; P < 0.01; RPE, r = -0.384, P < 0.05). The degree of exercise intensity during CCO-CPR is lower in individuals who have a higher peak work

  6. Utility of a simple lighting device to improve chest compressions learning.

    PubMed

    González-Calvete, L; Barcala-Furelos, R; Moure-González, J D; Abelairas-Gómez, C; Rodríguez-Núñez, A

    2017-04-08

    The recommendations on cardiopulmonary resuscitation (CPR) emphasize the quality of the manoeuvres, especially chest compressions (CC). Audiovisual feedback devices could improve the quality of the CC during CPR. The aim of this study was to evaluate the usefulness of a simple lighting device as a visual aid during CPR on a mannequin. Twenty-two paediatricians who attended an accredited paediatric CPR course performed, in random order, 2min of CPR on a mannequin without and with the help of a simple lighting device, which flashes at a frequency of 100 cycles per minute. The following CC variables were analyzed using a validated compression quality meter (CPRmeter(®)): depth, decompression, rate, CPR time and percentage of compressions. With the lighting device, participants increased average quality (60.23±54.50 vs. 79.24±9.80%; P=.005), percentage in target depth (48.86±42.67 vs. 72.95±20.25%; P=.036) and rate (35.82±37.54 vs. 67.09±31.95%; P=.024). A simple light device that flashes at the recommended frequency improves the quality of CC performed by paediatric residents on a mannequin. The usefulness of this CPR aid system should be assessed in real patients. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Two models of high frequency chest compression therapy: interaction of jacket pressure and mouth airflow.

    PubMed

    Lee, Yong Wan; Lee, Jongwon; Warwick, Warren J

    2007-01-01

    High frequency chest compression (HFCC) therapy assists clearing the secretions in the lung. This paper presents two mathematical models: 1) HFCC jacket function model (JFM) and 2) respiratory function model (RFM). JFM predicts the variation of the jacket pressure (Pj) from the respiratory pattern of mouth airflow (Fm). RFM predicts the HFCC induced mouth airflow (Fm) from the HFCC pulse pressures at the jacket (Pj). Fm and Pj were measured from a healthy subject during HFCC therapy. JFM, which was implemented with 2nd order system using prediction error method, shows the existence of breathing pattern at Pj. RFM, which was implemented with amplitude modulation technique, shows how the HFCC pulses affects to the Fm. JFM calculations match 78% of the measured respiratory pattern of Pj>. RFM calculations match 90% of measured HFCC induced Fm. These models can be used to test new breathing patterns before designing studies on patients having chronic obstructive pulmonary diseases.

  8. Evaluation of chest injury mechanisms in nearside oblique frontal impacts.

    PubMed

    Iraeus, Johan; Lindquist, Mats; Wistrand, Sofie; Sibgård, Elin; Pipkorn, Bengt

    2013-01-01

    Despite the use of seat belts and modern safety systems, many automobile occupants are still seriously injured or killed in car crashes. Common configurations in these crashes are oblique and small overlap frontal impacts that often lead to chest injuries.To evaluate the injury mechanism in these oblique impacts, an investigation was carried out using mathematical human body model simulations. A model of a simplified vehicle interior was developed and validated by means of mechanical sled tests with the Hybrid III dummy. The interior model was then combined with the human body model THUMS and validated by means of mechanical PMHS sled tests. Occupant kinematics as well as rib fracture patterns were predicted with reasonable accuracy.The final model was updated to conform to modern cars and a simulation matrix was run. In this matrix the boundary conditions, ΔV and PDOF, were varied and rib fracture risk as a function of the boundary conditions was evaluated using a statistical framework.In oblique frontal impacts, two injury producing mechanisms were found; (i) diagonal belt load and (ii) side structure impact. The second injury mechanism was found for PDOFs of 25°-35°, depending on ΔV. This means that for larger PDOFs, less ΔV is needed to cause a serious chest injury.

  9. Evaluation of Chest Injury Mechanisms in Nearside Oblique Frontal Impacts

    PubMed Central

    Iraeus, Johan; Lindquist, Mats; Wistrand, Sofie; Sibgård, Elin; Pipkorn, Bengt

    2013-01-01

    Despite the use of seat belts and modern safety systems, many automobile occupants are still seriously injured or killed in car crashes. Common configurations in these crashes are oblique and small overlap frontal impacts that often lead to chest injuries. To evaluate the injury mechanism in these oblique impacts, an investigation was carried out using mathematical human body model simulations. A model of a simplified vehicle interior was developed and validated by means of mechanical sled tests with the Hybrid III dummy. The interior model was then combined with the human body model THUMS and validated by means of mechanical PMHS sled tests. Occupant kinematics as well as rib fracture patterns were predicted with reasonable accuracy. The final model was updated to conform to modern cars and a simulation matrix was run. In this matrix the boundary conditions, ΔV and PDOF, were varied and rib fracture risk as a function of the boundary conditions was evaluated using a statistical framework. In oblique frontal impacts, two injury producing mechanisms were found; (i) diagonal belt load and (ii) side structure impact. The second injury mechanism was found for PDOFs of 25°–35°, depending on ΔV. This means that for larger PDOFs, less ΔV is needed to cause a serious chest injury. PMID:24406957

  10. The physiological effects and quality of chest compressions during CPR at sea level and high altitude.

    PubMed

    Wang, Jen-Chun; Tsai, Shih-Hung; Chen, Yu-Long; Hsu, Chin-Wang; Lai, Kuan-Cheng; Liao, Wen-I; Li, Ling-Yuan; Kao, Wei-Fong; Fan, Ju-Sing; Chen, Ying-Hsin

    2014-10-01

    Rescuers that undergo acute ascent without acclimatization can experience acute mountain sickness. Although performing cardiopulmonary resuscitation (CPR) for a short period requires intensive effort at sea level, performing CPR at high altitude is even more exhausting and can endanger the rescuer. Therefore, we conducted a pilot study to compare the quality of resuscitation in health professionals at high altitude (3100 m) and that at sea level. Thirty-eight participants were asked to performed continuous chest compression CPR (CCC-CPR) for 5 minutes at sea level and at high altitude. Cardiopulmonary resuscitation recording technology was used to objectively quantify the quality of the chest compressions (CCs), including the depth and rate thereof. At high altitude, rescuers showed a statistically significant decrease in blood oxygen saturation and an increase in systolic blood pressure, diastolic blood pressure, heart rate, and fatigue, as measured with the Borg score, after CCC-CPR compared with resting levels. The analysis of the time-dependent deterioration in the quality of CCC-CPR showed that the depth of CCs declined from the mean depth of the first 30 seconds after CCC-CPR to that at more than 120 seconds after CCC-CPR at both sea level and high altitude. The average number of effective CCs declined after CCC-CPR was performed for 1 minute at sea level and high altitude. The quality of CC rapidly declined at high altitude. At high altitude, the average number of effective CC decreases; and this decrease became significant after continuous CCs had been performed for 1 minute. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Dispatcher instruction of chest compression-only CPR increases actual provision of bystander CPR.

    PubMed

    Shimamoto, Tomonari; Iwami, Taku; Kitamura, Tetsuhisa; Nishiyama, Chika; Sakai, Tomohiko; Nishiuchi, Tatsuya; Hayashi, Yasuyuki; Kawamura, Takashi

    2015-11-01

    A preceding randomized controlled trial demonstrated that chest compression-only cardiopulmonary resuscitation (CPR) instruction by dispatcher was more effective to increase bystander CPR than conventional CPR instruction. However, the actual condition of implementation of each type of dispatcher instruction (chest compression-only CPR [CCCPR] or conventional CPR with rescue breathing) and provision of bystander CPR in real prehospital settings has not been sufficiently investigated. This registry prospectively enrolled patients aged =>18 years suffering an out-of-hospital cardiac arrest (OHCA) of non-traumatic causes before emergency-medical-service (EMS) arrival, who were considered as target subjects of dispatcher instruction, resuscitated by EMS personnel, and transported to medical institutions in Osaka, Japan from January 2005 through December 2012. The primary outcome measure was provision of CPR by a bystander. Multiple logistic regression analysis was used to assess factors that were potentially associated with provision of bystander CPR. Among 37,283 target subjects of dispatcher instruction, 5743 received CCCPR instruction and 13,926 received conventional CPR instruction. The proportion of CCCPR instruction increased from 5.7% in 2005 to 25.6% in 2012 (p for trend <0.001). The CCCPR instruction group received bystander CPR more frequently than conventional CPR instruction group (70.0% versus 62.1%, p<0.001). In the multivariable analysis, CCCPR dispatcher instruction was significantly associated with provision of bystander CPR compared with conventional CPR instruction (adjusted odds ratio 1.44, 95% CI 1.34-1.55). CCCPR dispatcher instruction among adult OHCA patients significantly increased the actual provision of bystander CPR. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. CPR PRO® device reduces rescuer fatigue during continuous chest compression cardiopulmonary resuscitation: a randomized crossover trial using a manikin model.

    PubMed

    Kovic, Ivor; Lulic, Dinka; Lulic, Ileana

    2013-10-01

    The performance of high-quality chest compressions with minimal interruptions is one of the most important elements of the "Chain of Survival." To evaluate the impact of a novel CPR PRO(®) (CPRO) device for manual chest compression on rescuer fatigue, pain, and cardiopulmonary resuscitation (CPR) quality. Randomized crossover trial of 24 health care professionals performing continuous chest compression CPR for 10 min with a CPRO device and conventional manual CPR (MCPR). Data about chest compressions were recorded using a manikin. Rescuers' physiologic signs were recorded before and after each session, and heart rate (HR) data were tracked continuously. Fatigue was assessed with ratings of perceived exertion, and pain questionnaire. All subjects completed 10 min of CPR with both methods. Significantly more rest breaks were taken during MCPR sessions (1.7 ± 2 vs. 0.21 ± 0.72). Subjects' perceived exertion was higher after MCPR, as well as the average (120.7 ± 16.8 vs. 110.8 ± 17.6) and maximal HR (134.3 ± 18.5 vs. 123.42 ± 16.5) during testing. Subjects reported more pain in the hands, especially the wrist, after performing MCPR. Average depth of compressions was higher with the CPRO device (4.6 ± 7.0 vs. 4.3 ± 7.9) and declined more slowly over time. Other CPR quality parameters, such as the correct position and complete release of pressure, were also better for CPRO CPR. CPRO device reduces rescuer fatigue and pain during continuous chest compression CPR, which results in a higher quality of CPR in a simulation setting. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. [Laryngeal Tube Position Shift after Chest Compression: Comparison of Fixation Methods Using Durapore Tape, Multipore Tape, or a Neck Tape].

    PubMed

    Seno, Hisayo; Komasawa, Nobuyasu; Fujiwara, Shunsuke; Miyazaki, Shinichiro; Tatsumi, Shinichi; Minami, Toshiaki

    2015-05-01

    The laryngeal tube (LT ; Smiths Medical, Minnesota, U. S. A) is an inflatable supraglottic device for emergency airway management such as during chest compression, the instability after insertion remains a problem. We investigated the effectiveness of three fixation methods of LT using a manikin and automated chest compressor. After 10-minute chest compression, LT without fixation was shifted by 0.4 ± 0.1 cm, which was greater than with Durapore tape (0.2 ± 0.1 cm), Multipore tape (0.2 ± 0.1 cm), or a neck tape (0.1 ± 0.1 cm). The shift of the position was smaller with neck tape fixation compared to Durapore or Multipore tape fixation. A fixation neck tape may be useful in stabilizing the inserted position of LT during cardiopulmonary resuscitation.

  14. End-Tidal CO2-Guided Chest Compression Delivery Improves Survival in a Neonatal Asphyxial Cardiac Arrest Model.

    PubMed

    Hamrick, Justin T; Hamrick, Jennifer L; Bhalala, Utpal; Armstrong, Jillian S; Lee, Jeong-Hoo; Kulikowicz, Ewa; Lee, Jennifer K; Kudchadkar, Sapna R; Koehler, Raymond C; Hunt, Elizabeth A; Shaffner, Donald H

    2017-08-16

    To determine whether end-tidal CO2-guided chest compression delivery improves survival over standard cardiopulmonary resuscitation after prolonged asphyxial arrest. Preclinical randomized controlled study. University animal research laboratory. 1-2-week-old swine. After undergoing a 20-minute asphyxial arrest, animals received either standard or end-tidal CO2-guided cardiopulmonary resuscitation. In the standard group, chest compression delivery was optimized by video and verbal feedback to maintain the rate, depth, and release within published guidelines. In the end-tidal CO2-guided group, chest compression rate and depth were adjusted to obtain a maximal end-tidal CO2 level without other feedback. Cardiopulmonary resuscitation included 10 minutes of basic life support followed by advanced life support for 10 minutes or until return of spontaneous circulation. Mean end-tidal CO2 at 10 minutes of cardiopulmonary resuscitation was 34 ± 8 torr in the end-tidal CO2 group (n = 14) and 19 ± 9 torr in the standard group (n = 14; p = 0.0001). The return of spontaneous circulation rate was 7 of 14 (50%) in the end-tidal CO2 group and 2 of 14 (14%) in the standard group (p = 0.04). The chest compression rate averaged 143 ± 10/min in the end-tidal CO2 group and 102 ± 2/min in the standard group (p < 0.0001). Neither asphyxia-related hypercarbia nor epinephrine administration confounded the use of end-tidal CO2-guided chest compression delivery. The response of the relaxation arterial pressure and cerebral perfusion pressure to the initial epinephrine administration was greater in the end-tidal CO2 group than in the standard group (p = 0.01 and p = 0.03, respectively). The prevalence of resuscitation-related injuries was similar between groups. End-tidal CO2-guided chest compression delivery is an effective resuscitation method that improves early survival after prolonged asphyxial arrest in this neonatal piglet model. Optimizing end-tidal CO2 levels during

  15. Chest compression fraction in ambulance while transporting patients with out-of-hospital cardiac arrest to the hospital in rural Taiwan.

    PubMed

    Hung, Shih-Chang; Mou, Ching-Yi; Hung, Hung-Chang; Lin, I-Hsiang; Lai, Shih-Wei; Huang, Jack YinChun

    2017-06-01

    Maintaining the standard two-handed chest compression is difficult in high-speed ambulances in rural areas. A retrospective, video-based, observational study was conducted from June to September 2013 in Nantou, a rural county of central Taiwan, to evaluate the chest compression fraction in an ambulance carriage during the travel from the scene to the hospital. The chest compression fraction was calculated as the chest compression time period divided by the ambulance travelling time period; the one-handed and two-handed chest compression fractions were also calculated. During the 4-month study period, a total of 102 videos that were recorded in an ambulance carriage were reviewed, including 97 cases of manual chest compressions. When there was only one emergency medical technician (EMT) in the carriage, the combined chest compression fraction was 50.6±20.7%; when there were two EMTs, the fraction was 58.3±16.0% and the fraction was 58.3±21.0% in a three-EMT scenario (p=0.221). Moreover, in the carriage, EMTs usually performed one-handed chest compressions. The chest compression fraction was low for patients with out-of-hospital cardiac arrest in a moving ambulance, irrespective of the number of providers. Reasons for this observation, as well as the effectiveness of the one-handed chest compression require further evaluation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  16. Improved chest recoil using an adhesive glove device for active compression-decompression CPR in a pediatric manikin model.

    PubMed

    Udassi, Jai P; Udassi, Sharda; Lamb, Melissa A; Lamb, Kenneth E; Theriaque, Douglas W; Shuster, Jonathan J; Zaritsky, Arno L; Haque, Ikram U

    2009-10-01

    We developed an adhesive glove device (AGD) to perform ACD-CPR in pediatric manikins, hypothesizing that AGD-ACD-CPR provides better chest decompression compared to standard (S)-CPR. Split-plot design randomizing 16 subjects to test four manikin-technique models in a crossover fashion to AGD-ACD-CPR vs. S-CPR. Healthcare providers performed 5min of CPR with 30:2 compression:ventilation ratio in the four manikin models: (1) adolescent; (2) child two-hand; (3) child one-hand; and (4) infant two-thumb. Modified manikins recorded compression pressure (CP), compression depth (CD) and decompression depth (DD). The AGD consisted of a modified oven mitt with an adjustable strap; a Velcro patch was sewn to the palmer aspect. The counter Velcro patch was bonded to the anterior chest wall. For infant CPR, the thumbs of two oven mitts were stitched together with Velcro. Subjects were asked to actively pull up during decompression. Subjects' heart rate (HR), respiratory rate (RR) and recovery time (RT) for HR/RR to return to baseline were recorded. Subjects were blinded to data recordings. Data (mean+/-SEM) were analyzed using a two-tailed paired t-test. Significance was defined qualitatively as P< or =0.05. Mean decompression depth difference was significantly greater with AGD-ACD-CPR compared to S-CPR; 38-75% of subjects achieved chest decompression to or beyond baseline. AGD-ACD-CPR provided 6-12% fewer chest compressions/minute than S-CPR group. There was no significant difference in CD, CP, HR, RR and RT within each group comparing both techniques. A simple, inexpensive glove device for ACD-CPR improved chest decompression with emphasis on active pull in manikins without excessive rescuer fatigue. The clinical implication of fewer compressions/minute in the AGD group needs to be evaluated.

  17. Out-of-hospital cardiopulmonary resuscitation strategies using one-handed chest compression technique for children suffering a cardiac arrest.

    PubMed

    Jung, Gun Hee; Oh, Je Hyeok; Kim, Chan Woong; Kim, Sung Eun; Lee, Dong Hoon

    2017-08-01

    We evaluated the decrease in chest compression depth during 30 : 2 compression-to-ventilation ratio one-handed chest compression (OHCC) in an out-of-hospital pediatric arrest setting, and whether switching hands every other cycle could maintain compression depth. A 5-year-old child-sized manikin was used, and 50 medical students participated in the present study. First, the participants performed 5 min OHCC with a 30 : 2 compression-to-ventilation ratio on the floor (baseline test). Second, the compression technique was changed from the OHCC to the two-handed chest compression when they became subjectively fatigued (test 1). Third, the compression hand was alternated every other cycle (test 2). Average compression depth (ACD) data were recorded using an accelerometer device. ACD changed significantly during the baseline test (0-1 min: 44.5±5.3 mm, 1-2 min: 43.7±6.1 mm, 2-3 min: 43.4±6.5 mm, 3-4 min: 43.2±6.5 mm, and 4-5 min: 42.3±6.5 mm, P=0.012). However, no significant differences were observed during test 1 or test 2. The baseline ACD value for the 4-5-min interval [95% confidence interval (CI), 40.5-44.2 mm] was significantly lower than those in test 1 (95% CI, 43.0-45.9 mm, P=0.004) and test 2 (95% CI, 42.4-45.9 mm, P=0.004). No differences in the ACDs at any interval were observed between test 1 and test 2. Compression depth decreased significantly after 4 min during 30 : 2 ratio OHCC. However, it was maintained by changing from the OHCC to the two-handed chest compression or by alternating compression hands every other cycle.

  18. A 10-s rest improves chest compression quality during hands-only cardiopulmonary resuscitation: a prospective, randomized crossover study using a manikin model.

    PubMed

    Min, Mun Ki; Yeom, Seok Ran; Ryu, Ji Ho; Kim, Yong In; Park, Maeng Real; Han, Sang Kyoon; Lee, Seong Hwa; Cho, Suck Ju

    2013-09-01

    This study was designed to assess changes in cardiopulmonary resuscitation (CPR) quality and rescuer fatigue when rescuers are provided with a break during continuous chest compression CPR (CCC-CPR). The present prospective, randomized crossover study involved 63 emergency medical technician trainees. The subjects performed three different CCC-CPR methods on a manikin model. The first method was general CCC-CPR without a break (CCC), the second included a 10-s break after 200 chest compressions (10/200), and the third included a 10-s break after 100 chest compressions (10/100). All methods were performed for 10 min. We counted the total number of compressions and those with appropriate depth every 1 min during the 10 min and measured mean compression depth from the start of chest compressions to 10 min. The 10/100 method showed the deepest compression depth, followed by the 10/200 and CCC methods. The mean compression depth showed a significant difference after 5 min had elapsed. The percentage of adequate compressions per min was calculated as the proportion of compressions with appropriate depth among total chest compressions. The percentage of adequate compressions declined over time for all methods. The 10/100 method showed the highest percentage of adequate compressions, followed by the 10/200 and CCC methods. When rescuers were provided a rest at a particular time during CCC-CPR, chest compression quality increased compared with CCC without rest. Therefore, we propose that a rescuer should be provided a rest during CCC-CPR, and specifically, we recommend a 10-s rest after 100 chest compressions. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  19. Assessment of effective face mask ventilation is compromised during synchronised chest compressions.

    PubMed

    Huynh, Trang; Hemway, Rae Jean; Perlman, Jeffrey M

    2015-01-01

    Delivery room cardiopulmonary resuscitation is rare. Recent evidence suggests that effective ventilation may be compromised during chest compressions (CC). To determine whether trained neonatal personnel can assess effective ventilation during CC in the setting of changing lung compliance. Neonatal providers (n=30) provided CC using a 3:1 CC to ventilation ratio performed for 2 min, with lung compliance adjusted every 30 s from 0.5 (low) to 1.0 mL/cmH2O (normal), followed by face mask ventilation (FMV) alone for 1 min. A neonatal lung simulator connected to a neonatal manikin was used to simulate the volume/pressure relation at low and normal compliance. Group analysis showed no difference in peak inflating pressure (PIP) at low versus normal compliance, but a threefold increase in tidal volume (TV) (p=0.00005) during synchronised CC. Paired analysis demonstrated minimal change in PIP, but a significant decrease in TV at low versus normal compliance. During FMV only, a significant decrease in PIP and increase in TV was noted with improved compliance. The face mask was incorrectly applied in 12 (40%) cases and in 20/30 (67%) providers did not perceive a change in compliance. During FMV only, 7/30 (23%) took corrective steps to achieve chest rise. Most providers cannot assess the effectiveness of delivered TV in the face of changing compliance during synchronised CC, limiting the ability to make appropriate and necessary adjustments. This may prolong cardiopulmonary resuscitation and result in escalating therapies unrelated to the delivery of effective ventilation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  20. Simplified dispatcher instructions improve bystander chest compression quality during simulated pediatric resuscitation.

    PubMed

    Rodriguez, Silvana Arciniegas; Sutton, Robert M; Berg, Marc D; Nishisaki, Akira; Maltese, Matthew; Meaney, Peter A; Niles, Dana E; Leffelman, Jessica; Berg, Robert A; Nadkarni, Vinay M

    2014-01-01

    Cardiopulmonary resuscitation (CPR) quality is associated with survival outcomes after out-of-hospital cardiac arrest. The objective of this study was to evaluate the effectiveness of simplified dispatcher CPR instructions to improve the chest compression (CC) quality during simulated pediatric cardiac arrest in public places. Adult bystanders recruited in public places were randomized to receive one of two scripted dispatcher CPR instructions: (1) "Push as hard as you can" (PUSH HARD) or (2) "Push approximately 2 inches" (TWO INCHES). A pediatric manikin with realistic CC characteristics (similar to a 6-year-old child), and a CPR recording defibrillator was used for quantitative CC data collection during a 2-min simulated pediatric scenario. The primary outcome was average CC depth treated as a continuous variable. Secondary outcomes included compliance with American Heart Association (AHA) CPR targets. Analysis was by two-sided unpaired t-test and Chi-square test, as appropriate. 128 out of 140 providers screened met inclusion/exclusion criteria and all 128 consented. The average CC depth (mean (SEM)) was greater in PUSH HARD compared to TWO INCHES (43 (1) vs. 36 (1) mm, p<0.01) and met AHA targets more often (39% (25/64) vs. 20% (13/64), p=0.02). CC rates trended higher in the PUSH HARD group (93 (4) vs. 82 (4) CC/min, p=0.06). More providers did not achieve full chest recoil with PUSH HARD compared to TWO INCHES (53% (34/64) vs. 75% (48/64), p=0.01). Simplified dispatcher assisted pediatric CPR instructions: "Push as hard as you can" was associated with lay bystanders providing deeper and faster CCs on a simulated, 6-year-old pediatric manikin. However, percentage of providers leaning between CC increased. The potential effect of these simplified instructions in younger children remains unanswered. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  1. Effects of chest wall compression on expiratory flow rates in patients with chronic obstructive pulmonary disease

    PubMed Central

    Nozoe, Masafumi; Mase, Kyoshi; Ogino, Tomoyuki; Murakami, Shigefumi; Takashima, Sachie; Domen, Kazuhisa

    2016-01-01

    Background: Manual chest wall compression (CWC) during expiration is a technique for removing airway secretions in patients with respiratory disorders. However, there have been no reports about the physiological effects of CWC in patients with chronic obstructive pulmonary disease (COPD). Objective: To compare the effects of CWC on expiratory flow rates in patients with COPD and asymptomatic controls. Method: Fourteen subjects were recruited from among patients with COPD who were receiving pulmonary rehabilitation at the University Hospital (COPD group). Fourteen age-matched healthy subjects were also consecutively recruited from the local community (Healthy control group). Airflow and lung volume changes were measured continuously with the subjects lying in supine position during 1 minute of quiet breathing (QB) and during 1 minute of CWC by a physical therapist. Results: During CWC, both the COPD group and the healthy control group showed significantly higher peak expiratory flow rates (PEFRs) than during QB (mean difference for COPD group 0.14 L/sec, 95% confidence interval (CI) 0.04 to 0.24, p<0.01, mean difference for healthy control group 0.39 L/sec, 95% CI 0.25 to 0.57, p<0.01). In the between-group comparisons, PEFR was significantly higher in the healthy control group than in the COPD group (-0.25 L/sec, 95% CI -0.43 to -0.07, p<0.01). However, the expiratory flow rates at the lung volume at the PEFR during QB and at 50% and 25% of tidal volume during QB increased in the healthy control group (mean difference for healthy control group 0.31 L/sec, 95% CI 0.15 to 0.47, p<0.01: 0.31 L/sec, 95% CI 0.15 to 0.47, p<0.01: 0.27 L/sec, 95% CI 0.13 to 0.41, p<0.01, respectively) but not in the COPD group (0.05 L/sec, 95% CI -0.01 to 0.12: -0.01 L/sec, 95% CI -0.11 to 0.08: 0.02 L/sec, 95% CI -0.05 to 0.90) with the application of CWC. Conclusion: The effects of chest wall compression on expiratory flow rates was different between COPD patients and asymptomatic

  2. A randomized comparison of three chest compression techniques and associated hemodynamic effect during infant CPR: A randomized manikin study.

    PubMed

    Smereka, Jacek; Szarpak, Lukasz; Rodríguez-Núñez, Antonio; Ladny, Jerzy R; Leung, Steve; Ruetzler, Kurt

    2017-10-01

    Pediatric cardiac arrest is an uncommon but critical life-threatening event requiring effective cardiopulmonary resuscitation. High-quality cardio-pulmonary resuscitation (CPR) is essential, but is poorly performed, even by highly skilled healthcare providers. The recently described two-thumb chest compression technique (nTTT) consists of the two thumbs directed at the angle of 90° to the chest while having the fingers fist-clenched. This technique might facilitate adequate chest-compression depth, chest-compression rate and rate of full chest-pressure relief. 42 paramedics from the national Emergency Medical Service of Poland performed three single-rescuer CPR sessions for 10 minutes each. Each session was randomly assigned to the conventional two-thumb (TTHT), the conventional two-finger (TFT) or the nTTT. The manikin used for this study was connected with an arterial blood pressure measurement device and blood measurements were documented on a 10-seconds cycle. The nTTT provided significant higher systolic (82 vs. 30 vs. 41 mmHg). A statistically significant difference was noticed between nTTT and TFT (p<.001), nTTT and TTHT (p<0.001), TFT and TTHT (p=0.003). The median diastolic preassure using nTTT was 16 mmHg compared with 9 mmHg for TFT (p<0.001), and 9.5 mmHg for TTHT (p<0.001). Mean arterial pressure using distinct methods varied and amounted to 40 vs. 22. vs. 26 mmHg (nTTT vs. TFT vs. TTHT, respectively). A statistically significant difference was noticed between nTTT and TFT (p<0.001), nTTT and TTEHT (p<0.001), and TFT and TTHT (p<0.001). The highest median pulse pressure was obtained by the nTTT 67.5 mmHg. Pulse pressure was 31.5 mmHg in the TTHT and 24 mmHg in the TFT. The difference between TFT and TTHT (p=0.025), TFT and nTTT (p<0.001), as well as between TTHT and nTTT (p<0.001) were statistically significant. The new nTTT technique generated higher arterial blood pressures compared to established chest compression techniques using an infant manikin

  3. A new defibrillator mode to reduce chest compression interruptions for health care professionals and lay rescuers: a pilot study in manikins.

    PubMed

    Barash, David M; Raymond, Richard P; Tan, Qing; Silver, Annemarie E

    2011-01-01

    Chest compression interruptions are detrimental during the resuscitation of cardiac arrest patients, especially immediately prior to shock delivery. To evaluate the effect of use of a new defibrillator technology, which filters compression-induced artifact and provides reliable rhythm analysis with automatic defibrillator charging during chest compressions, on preshock chest compression interruption. Thirty subjects (20 basic life support [BLS]; 10 advanced life support [ALS]) worked in pairs to perform two randomly ordered simulated cardiac resuscitations with the defibrillator operating in either standard mode (ALS = manual; BLS = automated external defibrillator [AED]) or the new Analysis and Charging during CPR (AC-CPR) mode. During each resuscitation simulation, rescuers switched roles as chest compressor and defibrillator operator every two segments of CPR (one segment = 2 minutes of chest compressions, rhythm analysis, and shock delivery, if appropriate), for eight total segments. The participants rested ≥30 minutes between trials and received brief AC-CPR training (BLS = 30 seconds; ALS = 5 minutes). Heart rate and perceived exertion were measured with pulse oximetry and the Borg scale, respectively. Mean (± standard deviation) preshock chest compression pause time was considerably shorter in each CPR segment with AC-CPR versus standard defibrillator operation (2.13 ± 0.99 sec vs. 10.93 ± 1.33, p < 0.0001), demonstrating effective use of AC-CPR with minimal training. Despite reduced chest compression interruption with AC-CPR, rescuer fatigue and perceived exertion did not differ in any CPR segment with standard defibrillator operation versus AC-CPR (p = 0.2-1.0). Preshock pause time is reduced by 80% utilizing a novel technology that employs automated analysis and charging during chest compression. Although chest compression pause time is reduced with the use of the new technology, participants do not excessively fatigue.

  4. Hyperinvasive approach to out-of hospital cardiac arrest using mechanical chest compression device, prehospital intraarrest cooling, extracorporeal life support and early invasive assessment compared to standard of care. A randomized parallel groups comparative study proposal. “Prague OHCA study”

    PubMed Central

    2012-01-01

    Background Out of hospital cardiac arrest (OHCA) has a poor outcome. Recent non-randomized studies of ECLS (extracorporeal life support) in OHCA suggested further prospective multicenter studies to define population that would benefit from ECLS. We aim to perform a prospective randomized study comparing prehospital intraarrest hypothermia combined with mechanical chest compression device, intrahospital ECLS and early invasive investigation and treatment in all patients with OHCA of presumed cardiac origin compared to a standard of care. Methods This paper describes methodology and design of the proposed trial. Patients with witnessed OHCA without ROSC (return of spontaneous circulation) after a minimum of 5 minutes of ACLS (advanced cardiac life support) by emergency medical service (EMS) team and after performance of all initial procedures (defibrillation, airway management, intravenous access establishment) will be randomized to standard vs. hyperinvasive arm. In hyperinvasive arm, mechanical compression device together with intranasal evaporative cooling will be instituted and patients will be transferred directly to cardiac center under ongoing CPR (cardiopulmonary resuscitation). After admission, ECLS inclusion/exclusion criteria will be evaluated and if achieved, veno-arterial ECLS will be started. Invasive investigation and standard post resuscitation care will follow. Patients in standard arm will be managed on scene. When ROSC achieved, they will be transferred to cardiac center and further treated as per recent guidelines. Primary outcome 6 months survival with good neurological outcome (Cerebral Performance Category 1–2). Secondary outcomes will include 30 day neurological and cardiac recovery. Discussion Authors introduce and offer a protocol of a proposed randomized study comparing a combined “hyperinvasive approach” to a standard of care in refractory OHCA. The protocol is opened for sharing by other cardiac centers with available ECLS and

  5. Using an inertial navigation algorithm and accelerometer to monitor chest compression depth during cardiopulmonary resuscitation.

    PubMed

    Boussen, Salah; Ibouanga-Kipoutou, Harold; Fournier, Nathalie; Raboutet, Yves Godio; Llari, Maxime; Bruder, Nicolas; Arnoux, Pierre Jean; Behr, Michel

    2016-09-01

    We present an original method using a low cost accelerometer and a Kalman-filter based algorithm to monitor cardiopulmonary resuscitation chest compressions (CC) depth. A three-axis accelerometer connected to a computer was used during CC. A Kalman filter was used to retrieve speed and position from acceleration data. We first tested the algorithm for its accuracy and stability on surrogate data. The device was implemented for CC performed on a manikin. Different accelerometer locations were tested. We used a classical inertial navigation algorithm to reconstruct CPR depth and frequency. The device was found accurate enough to monitor CPR depth and its stability was checked for half an hour without any drift. Average error on displacement was ±0.5mm. We showed that depth measurement was dependent on the device location on the patient or the rescuer. The accuracy and stability of this small low-cost accelerometer coupled to a Kalman-filter based algorithm to reconstruct CC depth and frequency, was found well adapted and could be easily implemented.

  6. Long-term retention of cardiopulmonary resuscitation skills after shortened chest compression-only training and conventional training: a randomized controlled trial.

    PubMed

    Nishiyama, Chika; Iwami, Taku; Kitamura, Tetsuhisa; Ando, Masahiko; Sakamoto, Tetsuya; Marukawa, Seishiro; Kawamura, Takashi

    2014-01-01

    It is unclear how much the length of a cardiopulmonary resuscitation (CPR) training program can be reduced without ruining its effectiveness. The authors aimed to compare CPR skills 6 months and 1 year after training between shortened chest compression-only CPR training and conventional CPR training. Participants were randomly assigned to either the compression-only CPR group, which underwent a 45-minute training program consisting of chest compressions and automated external defibrillator (AED) use with personal training manikins, or the conventional CPR group, which underwent a 180-minute training program with chest compressions, rescue breathing, and AED use. Participants' resuscitation skills were evaluated 6 months and 1 year after the training. The primary outcome measure was the proportion of appropriate chest compressions 1 year after the training. A total of 146 persons were enrolled, and 63 (87.5%) in the compression-only CPR group and 56 (75.7%) in the conventional CPR group completed the 1-year evaluation. The compression-only CPR group was superior to the conventional CPR group regarding the proportion of appropriate chest compression (mean ± SD = 59.8% ± 40.0% vs. 46.3% ± 28.6%; p = 0.036) and the number of appropriate chest compressions (mean ± SD = 119.5 ± 80.0 vs. 77.2 ± 47.8; p = 0.001). Time without chest compression in the compression-only CPR group was significantly shorter than that in the conventional CPR group (mean ± SD = 11.8 ± 21.1 seconds vs. 52.9 ± 14.9 seconds; p < 0.001). The shortened compression-only CPR training program appears to help the general public retain CPR skills better than the conventional CPR training program. UMIN-CTR UMIN000001675. © 2013 by the Society for Academic Emergency Medicine.

  7. Peyton's 4-Steps-Approach in comparison: Medium-term effects on learning external chest compression – a pilot study

    PubMed Central

    Münster, Tobias; Stosch, Christoph; Hindrichs, Nina; Franklin, Jeremy; Matthes, Jan

    2016-01-01

    Introduction: The external chest compression is a very important skill required to maintain a minimum of circulation during cardiac arrest until further medical procedures can be taken. Peyton’s 4-Steps-Approach is one method of skill training, the four steps being: Demonstration, Deconstruction, Comprehension and Execution. Based on CPR skill training, this method is widely, allegedly predominantly used, although there are insufficient studies on Peyton’s 4-Steps-Approach for skill training in CPR in comparison with other methods of skill training. In our study, we compared the medium- term effects on learning external chest compression with a CPR training device in three different groups: PEY (Peyton’s 4-Steps-Approach), PMOD (Peyton’s 4-Steps-Approach without Step 3) and STDM, the standard model, according to the widely spread method “see one, do one” (this is equal to Peyton’s step 1 and 3). Material and Methods: This prospective and randomised pilot study took place during the summer semester of 2009 at the SkillsLab and Simulation Centre of the University of Cologne (Kölner interprofessionelles Skills Lab und Simulationszentrum - KISS). The subjects were medical students (2nd and 3rd semester). They volunteered for the study and were randomised in three parallel groups, each receiving one of the teaching methods mentioned above. One week and 5/6 months after the intervention, an objective, structured single assessment was taken. Compression rate, compression depth, correct compressions, and the sum of correct checklist items were recorded. Additionally, we compared cumulative percentages between the groups based on the correct implementation of the resuscitation guidelines during that time. Results: The examined sample consisted of 134 subjects (68% female; age 22±4; PEY: n=62; PMOD: n=31; STDM: n=41). There was no difference between the groups concerning age, gender, pre-existing experience in CPR or time of last CPR course. The only

  8. Acute bag-valve breathing maneuvers plus manual chest compression is safe during stable septic shock: a randomized clinical trial

    PubMed Central

    Blattner, Clarissa Netto; dos Santos, Rafael Saldanha; Dias, Fernando Suparregui; Dias, Alexandre Simões; Mestriner, Régis Gemerasca; Vieira, Silvia Regina Rios

    2017-01-01

    Objective To evaluate the effects of bag-valve breathing maneuvers combined with standard manual chest compression techniques on safety, hemodynamics and oxygenation in stable septic shock patients. Design A parallel, assessor-blinded, randomized trial of two groups. A computer-generated list of random numbers was prepared by an independent researcher to allocate treatments. Setting The Intensive Care Unit at Hospital São Lucas, Pontifícia Universidade Católica do Rio Grande do Sul. Participants Fifty-two subjects were assessed for eligibility, and 32 were included. All included subjects (n = 32) received the allocated intervention (n = 19 for the Experimental Group and n = 13 for the Control Group). Intervention Twenty minutes of bag-valve breathing maneuvers combined with manual chest compression techniques (Experimental Group) or chest compression, as routinely used at our intensive care unit (Control Group). Follow-up was performed immediately after and at 30 minutes after the intervention. Main outcome measure Mean artery pressure. Results All included subjects completed the trial (N = 32). We found no relevant effects on mean artery pressure (p = 0.17), heart rate (p = 0.50) or mean pulmonary artery pressure (p = 0.89) after adjusting for subject age and weight. Both groups were identical regarding oxygen consumption after the data adjustment (p = 0.84). Peripheral oxygen saturation tended to increase over time in both groups (p = 0.05), and there was no significant association between cardiac output and venous oxygen saturation (p = 0.813). No clinical deterioration was observed. Conclusion A single session of bag-valve breathing maneuvers combined with manual chest compression is hemodynamically safe for stable septic-shocked subjects over the short-term. PMID:28444068

  9. Acute bag-valve breathing maneuvers plus manual chest compression is safe during stable septic shock: a randomized clinical trial.

    PubMed

    Blattner, Clarissa Netto; Santos, Rafael Saldanha Dos; Dias, Fernando Suparregui; Dias, Alexandre Simões; Mestriner, Régis Gemerasca; Vieira, Silvia Regina Rios

    2017-01-01

    To evaluate the effects of bag-valve breathing maneuvers combined with standard manual chest compression techniques on safety, hemodynamics and oxygenation in stable septic shock patients. A parallel, assessor-blinded, randomized trial of two groups. A computer-generated list of random numbers was prepared by an independent researcher to allocate treatments. The Intensive Care Unit at Hospital São Lucas, Pontifícia Universidade Católica do Rio Grande do Sul. Fifty-two subjects were assessed for eligibility, and 32 were included. All included subjects (n = 32) received the allocated intervention (n = 19 for the Experimental Group and n = 13 for the Control Group). Twenty minutes of bag-valve breathing maneuvers combined with manual chest compression techniques (Experimental Group) or chest compression, as routinely used at our intensive care unit (Control Group). Follow-up was performed immediately after and at 30 minutes after the intervention. Mean artery pressure. All included subjects completed the trial (N = 32). We found no relevant effects on mean artery pressure (p = 0.17), heart rate (p = 0.50) or mean pulmonary artery pressure (p = 0.89) after adjusting for subject age and weight. Both groups were identical regarding oxygen consumption after the data adjustment (p = 0.84). Peripheral oxygen saturation tended to increase over time in both groups (p = 0.05), and there was no significant association between cardiac output and venous oxygen saturation (p = 0.813). No clinical deterioration was observed. A single session of bag-valve breathing maneuvers combined with manual chest compression is hemodynamically safe for stable septic-shocked subjects over the short-term.

  10. Neonatal Resuscitation Program Rolling Refresher: Maintaining Chest Compression Proficiency Through the Use of Simulation-Based Education.

    PubMed

    Cepeda Brito, Jose R; Hughes, Patrick G; Firestone, Kimberly S; Ortiz Figueroa, Fabiana; Johnson, Karan; Ruthenburg, Terra; McKinney, Robyn; Gothard, M David; Ahmed, Rami

    2017-10-01

    Structured training courses have shown to improve patient outcomes; however, guidelines are inconsistently applied in up to 50% of all neonatal resuscitations. This is partly due to the fact that psychomotor skills needed for resuscitation decay within 6 months to a year from the completion of a certification course. Currently, there are no recommendations on how often refresher training should occur to prevent skill decay. Improve provider proficiency and confidence in the performance of neonatal resuscitation with a focus on chest compression effectiveness. The study recruited neonatal intensive care unit providers (n = 25). A simulation-based Neonatal Resuscitation Program (NRP) curriculum was developed and executed. Training sessions were delivered utilizing in situ simulations at varying time intervals. Pre- and postconfidence surveys and practicum skill scores were collected and evaluated by a content expert. Categorical data were summarized by frequency and percentage and tested for distributional equality via Pearson chi-square tests or Fisher exact tests depending on cell sample size distribution. All statistical tests were 2-sided with P < .05 considered statistically significant. Provider overall confidence and rate of chest compressions improved; however, there was no statistically significant difference between groups. Rolling refresher training at varied time intervals did not demonstrate statistically significant differences in chest compression quality among NRP providers. Rolling refresher training more frequently than every 6 months may not provide added benefit to NRP providers. Additional research is needed to determine optimal refresher training frequency to prevent skill decay.

  11. The impact of quantitative feedback on the performance of chest compression by basic life support trained clinical staff.

    PubMed

    Johnson, Matthew; Peat, Amanda; Boyd, Leanne; Warren, Tanya; Eastwood, Kathryn; Smith, Gavin

    2016-10-01

    The quality of CPR is directly related to survival outcomes following sudden cardiac arrest but, CPR competency amongst nursing and medical staff is generally poor. The skills honed in CPR recertification training rapidly decline in quality, even as soon as eight weeks following the training. High frequency low dose training has been recommended to address this decay in skills. Automated training devices that provide feedback may be useful in conducting low dose training, which would assist hospitals to manage the often logistically difficult, and financially costly exercise of conducting training programs. Little evidence is published about the improvement in skills performance that can be derived from isolated feedback from these training devices. To investigate whether the feedback from an automated training device can produce performance in a 'low dose' episode of re-training on chest compressions and compression depth for CPR. A repeated measures study was conducted assessing the compression rate and depth quality over 2min using a Laerdal QCPR® simulation manikin capable of recording performance data. On-screen feedback was provided to participants between attempts. Convenience sampling recruited undergraduate and qualified nursing and medical staff who were engaged in a CPR recertification program at a major Australian private hospital. In total, 150 participants were enrolled. Feedback from the automated training device was sufficient to produce a significant improvement in both chest compression rate (95% CI 13.3 to 19.7; p<0.001) and depth (95% CI 5.9 to 9.7; p<0.001) during the low dose training episode. The feedback provided from an automated training device was sufficient to produce an improvement in performance in chest compressions in CPR. This demonstrates an alternate staff training model that could improve patient outcomes, and allow for higher frequency training whilst potentially reducing costs and the logistical problems many medical

  12. Investigation of non-uniform airflow signal oscillation during high frequency chest compression

    PubMed Central

    Sohn, Kiwon; Warwick, Warren J; Lee, Yong W; Lee, Jongwon; Holte, James E

    2005-01-01

    Background High frequency chest compression (HFCC) is a useful and popular therapy for clearing bronchial airways of excessive or thicker mucus. Our observation of respiratory airflow of a subject during use of HFCC showed the airflow oscillation by HFCC was strongly influenced by the nonlinearity of the respiratory system. We used a computational model-based approach to analyse the respiratory airflow during use of HFCC. Methods The computational model, which is based on previous physiological studies and represented by an electrical circuit analogue, was used for simulation of in vivo protocol that shows the nonlinearity of the respiratory system. Besides, airflow was measured during use of HFCC. We compared the simulation results to either the measured data or the previous research, to understand and explain the observations. Results and discussion We could observe two important phenomena during respiration pertaining to the airflow signal oscillation generated by HFCC. The amplitudes of HFCC airflow signals varied depending on spontaneous airflow signals. We used the simulation results to investigate how the nonlinearity of airway resistance, lung capacitance, and inertance of air characterized the respiratory airflow. The simulation results indicated that lung capacitance or the inertance of air is also not a factor in the non-uniformity of HFCC airflow signals. Although not perfect, our circuit analogue model allows us to effectively simulate the nonlinear characteristics of the respiratory system. Conclusion We found that the amplitudes of HFCC airflow signals behave as a function of spontaneous airflow signals. This is due to the nonlinearity of the respiratory system, particularly variations in airway resistance. PMID:15904523

  13. Web-based general public opinion study of automated versus manual external chest compression.

    PubMed

    Lapostolle, Frédéric; Bertrand, Philippe; Agostinucci, Jean-Marc; Pradeau, Catherine; Tazarourte, Karim; Grave, Mélanie; Galinski, Michel; Adnet, Frédéric

    2014-06-01

    Only a few cardiac-arrest victims receive external chest compression (ECC) by a bystander. To test the hypothesis that the general public might start ECC more often if they used an automated device rather than a manual massage. Web-based public opinion survey based on two short videos, one showing manual ECC and the other automated ECC (Autopulse, Zoll, France). Advantages and disadvantages (perceived efficacy, reproducibility, hazard, apprehension and acceptability) of the two techniques were evaluated on a visual analogue scale (VAS). A VAS of 1-3 was considered to indicate preference for manual ECC, 8-10 for automated ECC and 4-7 for no clear preference. The final global score was the difference between advantage and disadvantage scores. Overall, 1769 persons answered the questionnaire. The median VAS score for each variable was as follows: 7 (25-75 percentiles, 5-9) for efficacy, 8 (3-10) for reproducibility, 5 (3-8) for hazard, 5 (2-8) for apprehension and 5 (2-8) for acceptability. The overall median score indicated that 1034 persons (58%) preferred use of the device, 618 (35%) preferred manual ECC and 117 (7%) had no preference. There was no significant difference in the preference according to gender, education and training in first aid. However, older persons (0) preferred the use of device. The better 'advantages over disadvantages' score for the automated ECC device over manual ECC indicated that the general public might envisage use of the device. This could contribute to increase the frequency of resuscitation attempts by bystanders. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  14. Prehospital randomised assessment of a mechanical compression device in cardiac arrest (PaRAMeDIC) trial protocol.

    PubMed

    Perkins, Gavin D; Woollard, Malcolm; Cooke, Matthew W; Deakin, Charles; Horton, Jessica; Lall, Ranjit; Lamb, Sarah E; McCabe, Chris; Quinn, Tom; Slowther, Anne; Gates, Simon

    2010-11-05

    Survival after out-of-hospital cardiac arrest is closely linked to the quality of CPR, but in real life, resuscitation during prehospital care and ambulance transport is often suboptimal. Mechanical chest compression devices deliver consistent chest compressions, are not prone to fatigue and could potentially overcome some of the limitations of manual chest compression. However, there is no high-quality evidence that they improve clinical outcomes, or that they are cost effective. The Prehospital Randomised Assessment of a Mechanical Compression Device In Cardiac Arrest (PARAMEDIC) trial is a pragmatic cluster randomised study of the LUCAS-2 device in adult patients with non-traumatic out-of-hospital cardiac arrest. The primary objective of this trial is to evaluate the effect of chest compression using LUCAS-2 on mortality at 30 days post out-of-hospital cardiac arrest, compared with manual chest compression. Secondary objectives of the study are to evaluate the effects of LUCAS-2 on survival to 12 months, cognitive and quality of life outcomes and cost-effectiveness. Ambulance service vehicles will be randomised to either manual compression (control) or LUCAS arms. Adult patients in out-of-hospital cardiac arrest, attended by a trial vehicle will be eligible for inclusion. Patients with traumatic cardiac arrest or who are pregnant will be excluded. The trial will recruit approximately 4000 patients from England, Wales and Scotland. A waiver of initial consent has been approved by the Research Ethics Committees. Consent will be sought from survivors for participation in the follow-up phase. The trial will assess the clinical and cost effectiveness of the LUCAS-2 mechanical chest compression device. The trial is registered on the International Standard Randomised Controlled Trial Number Registry (ISRCTN08233942).

  15. Effectiveness of simplified chest compression-only CPR training program with or without preparatory self-learning video: a randomized controlled trial.

    PubMed

    Nishiyama, Chika; Iwami, Taku; Kawamura, Takashi; Ando, Masahiko; Kajino, Kentaro; Yonemoto, Naohiro; Fukuda, Risa; Yuasa, Haruyuki; Yokoyama, Hiroyuki; Nonogi, Hiroshi

    2009-10-01

    To evaluate the effectiveness of 1-h practical chest compression-only cardiopulmonary resuscitation (CPR) training with or without a preparatory self-learning video. Participants were randomly assigned to either a control group or a video group who received a self-learning video before attending the 1-h chest compression-only CPR training program. The primary outcome measure was the total number of chest compressions during a 2-min test period. 214 participants were enrolled, 183 of whom completed this study. In a simulation test just before practical training began, 88 (92.6%) of the video group attempted chest compressions, while only 58 (64.4%) of the control group (p<0.001) did so. The total number of chest compressions was significantly greater in the video group than in the control group (100.5+/-61.5 versus 74.4+/-55.5, p=0.012). The proportion of those who attempted to use an automated external defibrillator (AED) was significantly greater in the video group (74.7% versus 28.7%, p<0.001). After the 1-h practical training, the number of total chest compressions markedly increased regardless of the type of CPR training program and inter-group differences had almost disappeared (161.0+/-31.8 in the video group and 159.0+/-35.7 in the control group, p=0.628). 1-h chest compression-only CPR training makes it possible for the general public to perform satisfactory chest compressions. Although a self-learning video encouraged people to perform CPR, their performance levels were not sufficient, confirming that practical training as well is essential. (UMIN000001046).

  16. Chest physiotherapy in mechanically ventilated patients without pneumonia—a narrative review

    PubMed Central

    De Regt, Jouke; Honoré, Patrick M.

    2017-01-01

    A beneficial adjuvant role of chest physiotherapy (CPT) to promote airway clearance, alveolar recruitment, and ventilation/perfusion matching in mechanically ventilated (MV) patients with pneumonia or relapsing lung atelectasis is commonly accepted. However, doubt prevails regarding the usefulness of applying routine CPT in MV subjects with no such lung diseases. In-depth narrative review based on a literature search for prospective randomized trials comparing CPT with a non-CPT strategy in adult patients ventilated for at least 48 h. Six relevant studies were identified. Sample size was small. Various CPT modalities were used including body positioning, manual chest manipulation (mobilization, percussion, vibration, and compression), and specific techniques such as lung hyperinflation and intrapulmonary percussion. Control subjects mostly received general nursing care and tracheal suction. In general, CPT was safe and supportive, yet had debatable or no significant impact on any relevant patient outcome parameter, including pneumonia. Current evidence does not support “prophylactic” CPT in adult MV patients without pneumonia. PMID:28203436

  17. Three cases of suprachoroidal hemorrhage associated with chest compression or asphyxiation and detected using postmortem computed tomography.

    PubMed

    Oshima, Toru; Yoshikawa, Hiroshi; Ohtani, Maki; Mimasaka, Sohtaro

    2015-05-01

    We report 3 cases of suprachoroidal hemorrhage (SCH) found to be triggered by increased intrathoracic pressure and detected using postmortem computed tomography (PMCT). Case 1 was a man aged in his 50s who was found dead at a landslide site. The autopsy showed clogging of the upper respiratory tract with soil debris from the landslide. The cause of death was determined to be asphyxia. PMCT showed SCH in both eyes, which was believed to be caused by chest compression or choking on the soil debris from the landslide. Case 2 was a woman aged in her 60s who was found dead in the sea. The autopsy revealed injuries primarily to her chest. We concluded that the cause of death was drowning. PMCT showed SCH in her right eye that was believed to be caused by chest compression. Case 3 was a woman aged in her 80s who was buried in a snowdrift and potentially died from hypothermia. PMCT showed SCH in both eyes, which was considered to be from an increase in intrathoracic pressure that might have been caused by the burial in the snow. Histological findings showed serous retinal detachment associated with retinal pigment epithelium damage due to SCH, which indicated that she was alive for several hours after the onset of SCH. The increase in intrathoracic pressure caused by dyspnea or chest compression was considered responsible for the onset of SCH in all of the present cases. PMCT might assist with the differential diagnosis of traumatic asphyxiation by SCH. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  18. Lung Injury in Asphyxiated Newborn Pigs Resuscitated from Cardiac Arrest - The Impact of Supplementary Oxygen, Longer Ventilation Intervals and Chest Compressions at Different Compression-to-Ventilation Ratios

    PubMed Central

    Dannevig, Ingrid; Solevåg, Anne L; Saugstad, Ola D; Nakstad, Britt

    2012-01-01

    Introduction: Non-specific lung inflammatory events caused by severe asphyxia may be intensified by the way we resuscitate the newly born. Assessing lung injury is potentially important because if alternative resuscitation approaches induces similar inflammatory responses or less lung injury. then we may choose the resuscitation approach that is most gentle, and easiest to perform and learn. We investigated the levels of lung inflammatory markers by comparing different ventilation, chest compression and inhaled oxygen fraction strategies in resuscitation of newly born pigs at cardiac arrest. Materials and Methodology: Progressive asphyxia in newborn pigs was induced until asystole occurred. With current resuscitation guidelines as a reference group, pigs were randomized to receive initial ventilation before chest compressions for 30s, 60s or 90s, or to compression-to-ventilation ratios 3:1or 9:3, or to resuscitation using pure oxygen or air. We analysed inflammatory markers in bronchoalveolar lavage fluid (BAL), IL8 and TNFα, and lung tissue qPCR for genes matrix metalloproteinases (MMP)2, MMP9, TNFα and ICAM-1. Results: BAL-levels of TNFα and IL8 tended to be higher in the 30s group compared to 60s group (p = 0.028 and p = 0.023, respectively) as was gene expression in lung tissue of ICAM-1 and MMP2 (p=0.012 and p=0.043, respectively). MMP2 expression was slightly higher in the 30s group compared to 90s group (p = 0.020). No differences were found between pigs resuscitated with C:V ratio 9:3 and 3:1 or pure oxygen versus air. Conclusion: Compared to current guidelines, with respect to lung injury, resuscitation with longer initial ventilation should be considered. Longer series of chest compressions did not change the lung inflammatory response, neither did the use of air instead of pure oxygen in severely asphyxiated pigs resuscitated from asystole. PMID:23115599

  19. A randomized trial of conventional chest physical therapy versus high frequency chest wall compressions in intubated and non-intubated adults.

    PubMed

    Clinkscale, Darnetta; Spihlman, Kathleen; Watts, Peggy; Rosenbluth, Daniel; Kollef, Marin H

    2012-02-01

    Conventional chest physical therapy (CCPT), applied by therapists using cupped hands to perform percussion, is commonly used in hospitalized adults. However, increased work load demands and occupational health concerns (eg, carpal tunnel syndrome) limit the overall utilization of this therapy. Therefore, we conducted a study to compare the overall effectiveness of CCPT to high-frequency chest wall compressions (HFCWC) applied via a vibratory vest. A single-center, randomized trial among hospitalized intubated and non-intubated adult patients requiring chest physical therapy comparing CCPT and HFCWC. The primary outcome measure was hospital stay. A total of 280 per-protocol patients (out of an a priori estimated 320 patients required to demonstrate a 20% relative reduction in hospital stay) were randomly assigned to receive CCPT (no. = 146, 52.1%) or HFCWC (no. = 134, 47.9%). The hospital stay was 12.5 ± 8.8 days for patients randomized to CCPT and 13.0 ± 8.9 days for patients randomized to HFCWC (P = .62). Patient comfort was assessed using a visual analog scale (increasing score reflects greater discomfort) and was statistically greater for patients randomized to CCPT compared to HFCWC (2.2 ± 0.8 vs 1.9 ± 0.8, P = .009). The duration of time until radiographic resolution of lobar atelectasis trended less for CCPT compared to HFCWC (5.2 ± 4.3 d vs 6.5 ± 5.2 d, P = .051). All other secondary outcomes, including hospital mortality and nosocomial pneumonia, were similar for both treatment groups. This study was inadequately powered for the primary outcome of interest and hence we cannot make recommendations on the preferential use of HFCWC or CCPT for intubated and non-intubated adult patients. HFCWC was associated with statistically better comfort scores. (ClinicalTrials.gov registration NCT00717873.).

  20. Continuous chest compression cardiopulmonary resuscitation training promotes rescuer self-confidence and increased secondary training: a hospital-based randomized controlled trial*.

    PubMed

    Blewer, Audrey L; Leary, Marion; Esposito, Emily C; Gonzalez, Mariana; Riegel, Barbara; Bobrow, Bentley J; Abella, Benjamin S

    2012-03-01

    Recent work suggests that delivery of continuous chest compression cardiopulmonary resuscitation is an acceptable layperson resuscitation strategy, although little is known about layperson preferences for training in continuous chest compression cardiopulmonary resuscitation. We hypothesized that continuous chest compression cardiopulmonary resuscitation education would lead to greater trainee confidence and would encourage wider dissemination of cardiopulmonary resuscitation skills compared to standard cardiopulmonary resuscitation training (30 compressions: two breaths). Prospective, multicenter randomized study. Three academic medical center inpatient wards. Adult family members or friends (≥ 18 yrs old) of inpatients admitted with cardiac-related diagnoses. In a multicenter randomized trial, family members of hospitalized patients were trained via the educational method of video self-instruction. Subjects were randomized to continuous chest compression cardiopulmonary resuscitation or standard cardiopulmonary resuscitation educational modes. Cardiopulmonary resuscitation performance data were collected using a cardiopulmonary resuscitation skill-reporting manikin. Trainee perspectives and secondary training rates were assessed through mixed qualitative and quantitative survey instruments. Chest compression performance was similar in both groups. The trainees in the continuous chest compression cardiopulmonary resuscitation group were significantly more likely to express a desire to share their training kit with others (152 of 207 [73%] vs. 133 of 199 [67%], p = .03). Subjects were contacted 1 month after initial enrollment to assess actual sharing, or "secondary training." Kits were shared with 2.0 ± 3.4 additional family members in the continuous chest compression cardiopulmonary resuscitation group vs. 1.2 ± 2.2 in the standard cardiopulmonary resuscitation group (p = .03). As a secondary result, trainees in the continuous chest compression

  1. Continuous chest compression cardiopulmonary resuscitation training promotes rescuer self-confidence and increased secondary training: A hospital-based randomized controlled trial

    PubMed Central

    Blewer, Audrey L.; Leary, Marion; Esposito, Emily C.; Gonzalez, Mariana; Riegel, Barbara; Bobrow, Bentley J.; Abella, Benjamin S.

    2013-01-01

    Objective Recent work suggests that delivery of continuous chest compression cardiopulmonary resuscitation is an acceptable layperson resuscitation strategy, although little is known about layperson preferences for cardiopulmonary resuscitation training in continuous chest compression cardiopulmonary resuscitation. We hypothesized that continuous chest compression cardiopulmonary resuscitation education would lead to greater trainee confidence and would encourage wider dissemination of cardiopulmonary resuscitation skills compared to standard cardiopulmonary resuscitation training (30 compressions: two breaths). Design Prospective, multicenter cohort study. Setting Three academic medical center inpatient wards. Subjects Adult family members or friends (≥18 yrs old) of inpatients admitted with cardiac-related diagnoses. Interventions In a multicenter randomized trial, family members of hospitalized patients were trained via the educational method of video self-instruction. Subjects were randomized to continuous chest compression cardiopulmonary resuscitation or standard cardiopulmonary resuscitation educational modes. Measurements Cardiopulmonary resuscitation performance data were collected using a cardiopulmonary resuscitation skill-reporting manikin. Trainee perspectives and secondary training rates were assessed through mixed qualitative and quantitative survey instruments. Main Results Chest compression performance was similar in both groups. The trainees in the continuous chest compression cardiopulmonary resuscitation group were significantly more likely to express a desire to share their training kit with others (152 of 207 [73%] vs. 133 of 199 [67%], p = .03). Subjects were contacted 1 month after initial enrollment to assess actual sharing, or “secondary training.” Kits were shared with 2.0 ± 3.4 additional family members in the continuous chest compression cardiopulmonary resuscitation group vs. 1.2 ± 2.2 in the standard cardiopulmonary

  2. Competing hydrostatic compression mechanisms in nickel cyanide

    NASA Astrophysics Data System (ADS)

    Adamson, J.; Lucas, T. C.; Cairns, A. B.; Funnell, N. P.; Tucker, M. G.; Kleppe, A. K.; Hriljac, J. A.; Goodwin, A. L.

    2015-12-01

    We use variable-pressure neutron and X-ray diffraction measurements to determine the uniaxial and bulk compressibilities of nickel(II) cyanide, Ni(CN)2. Whereas other layered molecular framework materials are known to exhibit negative area compressibility, we find that Ni(CN)2 does not. We attribute this difference to the existence of low-energy in-plane tilt modes that provide a pressure-activated mechanism for layer contraction. The experimental bulk modulus we measure is about four times lower than that reported elsewhere on the basis of density functional theory methods [Phys. Rev. B 83 (2011) 024301].

  3. Compression failure mechanisms of composite structures

    NASA Technical Reports Server (NTRS)

    Hahn, H. T.; Sohi, M.; Moon, S.

    1986-01-01

    An experimental and analytical study was conducted to delineate the compression failure mechanisms of composite structures. The present report summarizes further results on kink band formation in unidirectional composites. In order to assess the compressive strengths and failure modes of fibers them selves, a fiber bundle was embedded in epoxy casting and tested in compression. A total of six different fibers were used together with two resins of different stiffnesses. The failure of highly anisotropic fibers such as Kevlar 49 and P-75 graphite was due to kinking of fibrils. However, the remaining fibers--T300 and T700 graphite, E-glass, and alumina--failed by localized microbuckling. Compressive strengths of the latter group of fibers were not fully utilized in their respective composite. In addition, acoustic emission monitoring revealed that fiber-matrix debonding did not occur gradually but suddenly at final failure. The kink band formation in unidirectional composites under compression was studied analytically and through microscopy. The material combinations selected include seven graphite/epoxy composites, two graphite/thermoplastic resin composites, one Kevlar 49/epoxy composite and one S-glass/epoxy composite.

  4. Prediction of perceptible artifacts in JPEG 2000-compressed chest CT images using mathematical and perceptual quality metrics.

    PubMed

    Kim, Bohyoung; Lee, Kyoung Ho; Kim, Kil Joong; Mantiuk, Rafal; Hahn, Seokyung; Kim, Tae Jung; Kim, Young Hoon

    2008-02-01

    The objective of our study was to determine whether peak signal-to-noise ratio (PSNR) and a perceptual quality metric (High-Dynamic Range Visual Difference Predictor [HDR-VDP]) can predict the presence of perceptible artifacts in Joint Photographic Experts Group (JPEG) 2000-compressed chest CT images. One hundred chest CT images were compressed to 5:1, 8:1, 10:1, and 15:1. Five radiologists determined if the original and compressed images were identical (negative response) or different (positive response). The correlation between the results for each metric and the number of readers with positive responses was evaluated using Spearman's rank correlation test. Using the pooled readers' responses as the reference standard, we performed receiver operating characteristic (ROC) analysis to determine the cutoff values balancing sensitivity and specificity and yielding 100% sensitivity in each metric. These cutoff values were then used to estimate the visually lossless thresholds for the compressions for the 100 original images, and the accuracy of the estimates of two metrics was compared (McNemar test). The correlation coefficients were -0.918 and 0.925 for PSNR and the HDR-VDP, respectively. The areas under the ROC curves for the two metrics were 0.983 and 0.984, respectively (p = 0.11). The PSNR and HDR-VDP accurately predicted the visually lossless threshold for 69% and 72% of the 100 images (p = 0.68), respectively, at the cutoff values balancing sensitivity and specificity and for 43% and 47% (p = 0.22), respectively, at the cutoff values reaching 100% sensitivity. Both metrics are promising in predicting the perceptible compression artifacts and therefore can potentially be used to estimate the visually lossless threshold.

  5. Mechanically induced sudden death in chest wall impact (commotio cordis).

    PubMed

    Link, Mark S

    2003-01-01

    Sudden death due to nonpenetrating chest wall impact in the absence of injury to the ribs, sternum and heart is known as commotio cordis. Although once thought rare, an increasing number of these events have been reported. Indeed, a significant percentage of deaths on the athletic field are due to chest wall impact. Commotio cordis is most frequently observed in young individuals (age 4-18 years), but may also occur in adults. Sudden death is instantaneous or preceded by several seconds of lightheadedness after the chest wall blow. Victims are most often found in ventricular fibrillation, and successful resuscitation is more difficult than expected given the young age, excellent health of the victims, and the absence of structural heart disease. Autopsy examination is notable for the lack of any significant cardiac or thoracic abnormalities. In an experimental model of commotio cordis utilizing anesthetized juvenile swine, ventricular fibrillation can be produced by a 30 mph baseball strike if the strike occurred during the vulnerable period of repolarization, on the upslope of the T-wave. Energy of the impact object was also found to be a critical variable with 40 mph baseballs more likely to cause ventricular fibrillation than velocities less or greater than 40 mph. In addition, more rigid impact objects and blows directly over the center of the chest were more likely to cause ventricular fibrillation. Peak left ventricular pressure generated by the chest wall blow correlated with the risk of ventricular fibrillation. Activation of the K(+)(ATP) channel is a likely cause of the ventricular fibrillation produced by chest wall blows. Successful resuscitation is attainable with early defibrillation.

  6. The evaluation of upper body muscle activity during the performance of external chest compressions in simulated hypogravity

    NASA Astrophysics Data System (ADS)

    Krygiel, Rebecca G.; Waye, Abigail B.; Baptista, Rafael Reimann; Heidner, Gustavo Sandri; Rehnberg, Lucas; Russomano, Thais

    2014-04-01

    BACKGROUND: This original study evaluated the electromyograph (EMG) activity of four upper body muscles: triceps brachii, erector spinae, upper rectus abdominis, and pectoralis major, while external chest compressions (ECCs) were performed in simulated Martian hypogravity using a Body Suspension Device, counterweight system, and standard full body cardiopulmonary resuscitation (CPR) mannequin. METHOD: 20 young, healthy male subjects were recruited. One hundred compressions divided into four sets, with roughly six seconds between each set to indicate 'ventilation', were performed within approximately a 1.5 minute protocol. Chest compression rate, depth and number were measured along with the subject's heart rate (HR) and rating of perceived exertion (RPE). RESULTS: All mean values were used in two-tailed t-tests using SPSS to compare +1 Gz values (control) versus simulated hypogravity values. The AHA (2005) compression standards were maintained in hypogravity. RPE and HR increased by 32% (p < 0.001) and 44% (p = 0.002), respectively, when ECCs were performed during Mars simulation, in comparison to +1 Gz. In hypogravity, the triceps brachii showed significantly less activity (p < 0.001) when compared with the other three muscles studied. The comparison of all the other muscles showed no difference at +1 Gz or in hypogravity. CONCLUSIONS: This study was among the first of its kind, however several limitations were faced which hopefully will not exist in future studies. Evaluation of a great number of muscles will allow space crews to focus on specific strengthening exercises within their current training regimes in case of a serious cardiac event in hypogravity.

  7. A randomized trial of the capability of elderly lay persons to perform chest compression only CPR versus standard 30:2 CPR.

    PubMed

    Neset, Andres; Birkenes, Tonje S; Myklebust, Helge; Mykletun, Reidar J; Odegaard, Silje; Kramer-Johansen, Jo

    2010-07-01

    Early cardiopulmonary resuscitation (CPR) improves survival after cardiac arrest, but there is a discrepancy between the age group normally attending CPR-classes and the age group most likely to witness a cardiac arrest. We wanted to study if elderly lay persons could perform 10min of CPR on a realistic manikin with continuous chest compressions (CCC) and conventional CPR (30:2). Volunteers were tested 5-7 months after CPR-classes. They were randomized to CCC or 30:2, and to receive feedback (FB) or not. Quality of CPR, age adjusted maximum heart rate (HRmax), and subjective exhaustion ratings were measured and evaluated in a blinded fashion. Temporal development and group differences were evaluated with ANOVA procedures. All 64 volunteers were able to perform CPR for 10min and rated their efforts as mild to moderate in concordance with a mean HRmax of 78%. Quality of CPR was similar in all groups, except for chest compression rate that was slightly higher and had less variability in the FB group. Overall chest compression depth was 41+/-4.5mm. Analysis of temporal development of chest compression depth revealed a small initial decline before leveling off. As expected, CCC group had less pauses and higher total number of chests compressions. Lay people in the age group 50-76 were able to perform CPR with acceptable quality for 10min and we found only very slight temporal quality deterioration. This makes training programs for the elderly meaningful to improve survival after cardiac arrest.

  8. Development and validation of an improved mechanical thorax for simulating cardiopulmonary resuscitation with adjustable chest stiffness and simulated blood flow.

    PubMed

    Eichhorn, Stefan; Spindler, Johannes; Polski, Marcin; Mendoza, Alejandro; Schreiber, Ulrich; Heller, Michael; Deutsch, Marcus Andre; Braun, Christian; Lange, Rüdiger; Krane, Markus

    2017-02-24

    Investigations of compressive frequency, duty cycle, or waveform during CPR are typically rooted in animal research or computer simulations. Our goal was to generate a mechanical model incorporating alternate stiffness settings and an integrated blood flow system, enabling defined, reproducible comparisons of CPR efficacy. Based on thoracic stiffness data measured in human cadavers, such a model was constructed using valve-controlled pneumatic pistons and an artificial heart. This model offers two realistic levels of chest elasticity, with a blood flow apparatus that reflects compressive depth and waveform changes. We conducted CPR at opposing levels of physiologic stiffness, using a LUCAS device, a motor-driven plunger, and a group of volunteers. In high-stiffness mode, blood flow generated by volunteers was significantly less after just 2min of CPR, whereas flow generated by LUCAS device was superior by comparison. Optimal blood flow was obtained via motor-driven plunger, with trapezoidal waveform.

  9. Pauses in chest compression and inappropriate shocks: a comparison of manual and semi-automatic defibrillation attempts.

    PubMed

    Kramer-Johansen, Jo; Edelson, Dana P; Abella, Benjamin S; Becker, Lance B; Wik, Lars; Steen, Petter Andreas

    2007-05-01

    Semi-automatic defibrillation requires pauses in chest compressions during ECG analysis and charging, and prolonged pre-shock compression pauses reduce the chance of a return of spontaneous circulation (ROSC). We hypothesised that pauses are shorter for manual defibrillation by trained rescuers, but with an increased number of inappropriate shocks given for a non-VF/VT rhythm. From a prospective study of CPR quality during in- and out-of-hospital cardiac arrest, the duration of pre-shock, inter-shock, and post-shock pauses were compared with Mann-Whitney U-test during manual and AED mode with the same defibrillator, and proportions of inappropriate shocks were compared with Chi-squared tests. A 635 manual and 530 semi-automatic shocks were studied. Number of shocks per episode was similar for the two groups. All pauses measured in seconds (s) were shorter for manual use (P<0.0001); median (25, 75 percentiles); 15 (11, 21) versus 22 (18, 28) pre-shock, 13 (9, 20) versus 23 (22, 26) inter-shock, and 9 (6, 18) versus 20 (11, 31) post-shock, but 163 (26%) manual shocks were inappropriate compared with 30 (6%) AED shocks, odds ratio (OR) 5.7 (95% CI; 3.8-8.7). A 150 (78%) of the inappropriate shocks were delivered for organised rhythms. The proportion of inappropriate manual shocks was higher for resident physicians in-hospital than paramedics out-of-hospital; 77/228 (34%) versus 86/407 (21%), OR 1.9 (1.3-2.7). Manual defibrillation resulted in shorter pauses in chest compressions, but a higher frequency of inappropriate shocks. A higher formal level of education did not prevent inappropriate shocks. Trial registrationhttp://www.clinicaltrials.gov/ (NCT00138996 and NCT00228293).

  10. Real-Time Mobile Device-Assisted Chest Compression During Cardiopulmonary Resuscitation.

    PubMed

    Sarma, Satyam; Bucuti, Hakiza; Chitnis, Anurag; Klacman, Alex; Dantu, Ram

    2017-07-15

    Prompt administration of high-quality cardiopulmonary resuscitation (CPR) is a key determinant of survival from cardiac arrest. Strategies to improve CPR quality at point of care could improve resuscitation outcomes. We tested whether a low cost and scalable mobile phone- or smart watch-based solution could provide accurate measures of compression depth and rate during simulated CPR. Fifty health care providers (58% intensive care unit nurses) performed simulated CPR on a calibrated training manikin (Resusci Anne, Laerdal) while wearing both devices. Subjects received real-time audiovisual feedback from each device sequentially. Primary outcome was accuracy of compression depth and rate compared with the calibrated training manikin. Secondary outcome was improvement in CPR quality as defined by meeting both guideline-recommend compression depth (5 to 6 cm) and rate (100 to 120/minute). Compared with the training manikin, typical error for compression depth was <5 mm (smart phone 4.6 mm; 95% CI 4.1 to 5.3 mm; smart watch 4.3 mm; 95% CI 3.8 to 5.0 mm). Compression rates were similarly accurate (smart phone Pearson's R = 0.93; smart watch R = 0.97). There was no difference in improved CPR quality defined as the number of sessions meeting both guideline-recommended compression depth (50 to 60 mm) and rate (100 to 120 compressions/minute) with mobile device feedback (60% vs 50%; p = 0.3). Sessions that did not meet guideline recommendations failed primarily because of inadequate compression depth (46 ± 2 mm). In conclusion, a mobile device application-guided CPR can accurately track compression depth and rate during simulation in a practice environment in accordance with resuscitation guidelines. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Development of a diagnostic glove for unobtrusive measurement of chest compression force and depth during neonatal CPR.

    PubMed

    Dellimore, Kiran; Heunis, Stephan; Gohier, Francis; Archer, Elize; de Villiers, Adéle; Smith, Johan; Scheffer, Cornie

    2013-01-01

    Optimizing chest compression (CC) performance during neonatal cardiopulmonary resuscitation (CPR) is critical to improving survival outcomes since current clinical protocols often achieve only a fraction of the native cardiovascular perfusion. This study presents the development of a diagnostic tool to unobtrusively measure the CC depth and force during neonatal CPR using sensors mounted on a glove platform. The performance of the glove was evaluated by infant manikin tests using the two-thumb (TT) and two-finger (TF) methods of CC during simulated, unventilated neonatal CPR. The TT method yielded maximum CC depths and forces of as much as 25.7 ± 3.2 mm and 35.9 ± 2.2 N while the TF method produced CC depths and forces of as much as 21.6 ± 2.2 mm and 23.7 ± 2.9 N. These results are consistent with clinical findings which suggest that TT compression is more effective than TF compression since it produces greater CC depths and forces.

  12. Drug release mechanisms of compressed lipid implants.

    PubMed

    Kreye, F; Siepmann, F; Siepmann, J

    2011-02-14

    The aim of this study was to elucidate the mass transport mechanisms controlling drug release from compressed lipid implants. The latter steadily gain in importance as parenteral controlled release dosage forms, especially for acid-labile drugs. A variety of lipid powders were blended with theophylline and propranolol hydrochloride as sparingly and freely water-soluble model drugs. Cylindrical implants were prepared by direct compression and thoroughly characterized before and after exposure to phosphate buffer pH 7.4. Based on the experimental results, an appropriate mathematical theory was identified in order to quantitatively describe the resulting drug release patterns. Importantly, broad release spectra and release periods ranging from 1 d to several weeks could easily be achieved by varying the type of lipid, irrespective of the type of drug. Interestingly, diffusion with constant diffusivities was found to be the dominant mass transport mechanism, if the amount of water within the implant was sufficient to dissolve all of the drug. In these cases an analytical solution of Fick's second law could successfully describe the experimentally measured theophylline and propranolol hydrochloride release profiles, even if varying formulation and processing parameters, e.g. the type of lipid, initial drug loading, drug particles size as well as compression force and time. However, based on the available data it was not possible to distinguish between drug diffusion control and water diffusion control. The obtained new knowledge can nevertheless significantly help facilitating the optimization of this type of advanced drug delivery systems, in particular if long release periods are targeted, which require time consuming experimental trials.

  13. Neurological mechanisms of chest pain and cardiac disease.

    PubMed

    Foreman, Robert D

    2007-02-01

    SCS is an efficacious, reversible, and safe therapy that improves quality of life, increases exercise tolerance, and relieves angina pectoris, but clinical trials in North America are needed to confirm the data coming from Europe. Neuronal convergence onto STT cells underlies the referred pain associated with angina pectoris. With pain referred to the chest and upper arm, cardiac nociceptive information is transmitted via sympathetic afferent fibers to thoracic cells. With pain referred to the jaw and neck, cardiac nociceptive information is transmitted via vagal afferent fibers onto cervical cells. SCS can modulate the responses of thoracic STT cells to nociceptive input originating from the heart. SCS modulates cardiac function. It stabilizes neurons in the intrinsic cardiac nervous system, and can reduce infarct size via adrenoreceptors.

  14. Impact of physical fitness and biometric data on the quality of external chest compression: a randomised, crossover trial.

    PubMed

    Russo, Sebastian G; Neumann, Peter; Reinhardt, Sylvia; Timmermann, Arnd; Niklas, André; Quintel, Michael; Eich, Christoph B

    2011-11-04

    During circulatory arrest, effective external chest compression (ECC) is a key element for patient survival. In 2005, international emergency medical organisations changed their recommended compression-ventilation ratio (CVR) from 15:2 to 30:2 to acknowledge the vital importance of ECC. We hypothesised that physical fitness, biometric data and gender can influence the quality of ECC. Furthermore, we aimed to determine objective parameters of physical fitness that can reliably predict the quality of ECC. The physical fitness of 30 male and 10 female healthcare professionals was assessed by cycling and rowing ergometry (focussing on lower and upper body, respectively). During ergometry, continuous breath-by-breath ergospirometric measurements and heart rate (HR) were recorded. All participants performed two nine-minute sequences of ECC on a manikin using CVRs of 30:2 and 15:2. We measured the compression and decompression depths, compression rates and assessed the participants' perception of exhaustion and comfort. The median body mass index (BMI; male 25.4 kg/m2 and female 20.4 kg/m2) was used as the threshold for subgroup analyses of participants with higher and lower BMI. HR during rowing ergometry at 75 watts (HR75) correlated best with the quality of ECC (r = -0.57, p < 0.05). Participants with a higher BMI and better physical fitness performed better and showed less fatigue during ECC. These results are valid for the entire cohort, as well as for the gender-based subgroups. The compressions of female participants were too shallow and more rapid (mean compression depth was 32 mm and rate was 117/min with a CVR of 30:2). For participants with a lower BMI and higher HR75, the compression depth decreased over time, beginning after four minutes for the 15:2 CVR and after three minutes for the 30:2 CVR. Although found to be more exhausting, a CVR of 30:2 was rated as being more comfortable. The quality of the ECC and fatigue can both be predicted by BMI and physical

  15. The unique contribution of manual chest compression-vibrations to airflow during physiotherapy in sedated, fully ventilated children.

    PubMed

    Gregson, Rachael K; Shannon, Harriet; Stocks, Janet; Cole, Tim J; Peters, Mark J; Main, Eleanor

    2012-03-01

    This study aimed to quantify the specific effects of manual lung inflations with chest compression-vibrations, commonly used to assist airway clearance in ventilated patients. The hypothesis was that force applied during the compressions made a significant additional contribution to increases in peak expiratory flow and expiratory to inspiratory flow ratio over and above that resulting from accompanying increases in inflation volume. Prospective observational study. Cardiac and general pediatric intensive care. Sedated, fully ventilated children. Customized force-sensing mats and a commercial respiratory monitor recorded force and respiration during physiotherapy. Percentage changes in peak expiratory flow, peak expiratory to inspiratory flow ratios, inflation volume, and peak inflation pressure between baseline and manual inflations with and without compression-vibrations were calculated. Analysis of covariance determined the relative contribution of changes in pressure, volume, and force to influence changes in peak expiratory flow and peak expiratory to inspiratory flow ratio. Data from 105 children were analyzed (median age, 1.3 yrs; range, 1 wk to 15.9 yrs). Force during compressions ranged from 15 to 179 N (median, 46 N). Peak expiratory flow increased on average by 76% during compressions compared with baseline ventilation. Increases in peak expiratory flow were significantly related to increases in inflation volume, peak inflation pressure, and force with peak expiratory flow increasing by, on average, 4% for every 10% increase in inflation volume (p < .001), 5% for every 10% increase in peak inflation pressure (p = .005), and 3% for each 10 N of applied force (p < .001). By contrast, increase in peak expiratory to inspiratory flow ratio was only related to applied force with a 4% increase for each 10 N of force (p < .001). These results provide evidence of the unique contribution of compression forces in increasing peak expiratory flow and peak expiratory

  16. Miniaturized mechanical chest compressor improves calculated cerebral perfusion pressure without compromising intracranial pressure during cardiopulmonary resuscitation in a porcine model of cardiac arrest.

    PubMed

    Xu, Jiefeng; Hu, Xianwen; Yang, Zhengfei; Wu, Xiaobo; Bisera, Joe; Sun, Shijie; Tang, Wanchun

    2014-05-01

    One of the major goals of cardiopulmonary resuscitation (CPR) is to provide adequate oxygen delivery to the brain for minimizing cerebral injury resulted from cardiac arrest. The optimal chest compression during CPR should effectively improve brain perfusion without compromising intracranial pressure (ICP). Our previous study has demonstrated that the miniaturized mechanical chest compressor improved hemodynamic efficacy and the success of CPR. In the present study, we investigated the effects of the miniaturized chest compressor (MCC) on calculated cerebral perfusion pressure (CerPP) and ICP. Ventricular fibrillation was electrically induced and untreated for 7min in 13 male domestic pigs weighing 39±3kg. The animals were randomized to receive mechanical chest compression with the MCC (n=7), or the Thumper device (n=6). CPR was performed for 5min before defibrillation attempt by a single 150J shock. At 2.5min of CPR, the epinephrine at a dose of 20μg/kg was administered. Additional epinephrine was administered at an interval of 3min thereafter. If resuscitation was not successful, CPR was resumed for an additional 2min prior to the next defibrillation until successful resuscitation or for a total of 15min. Post-resuscitated animals were observed for 2h. Significantly greater intrathoracic positive and negative pressures during compression and decompression phases of CPR were observed with the MCC when compared with the Thumper device. The MCC produced significantly greater coronary perfusion pressure and end-tidal carbon dioxide. There were no statistically significant differences in systolic and mean ICP between the two groups; however, both of the measurements were slightly greater in the MCC treated animals. Interestingly, the diastolic ICP was significantly lower in the MCC group, which was closely related to the significantly lower negative intrathoracic pressure in the animals that received the MCC. Most important, systolic, diastolic and mean calculated

  17. Leaning during chest compressions impairs cardiac output and left ventricular myocardial blood flow in piglet cardiac arrest

    PubMed Central

    Zuercher, Mathias; Hilwig, Ronald W.; Ranger-Moore, James; Nysaether, Jon; Nadkarni, Vinay M.; Berg, Marc D.; Kern, Karl B.; Sutton, Robert; Berg, Robert A.

    2012-01-01

    Objective Complete recoil of the chest wall between chest compressions during cardiopulmonary resuscitation is recommended, because incomplete chest wall recoil from leaning may decrease venous return and thereby decrease blood flow. We evaluated the hemodynamic effect of 10% or 20% lean during piglet cardiopulmonary resuscitation. Design Prospective, sequential, controlled experimental animal investigation. Setting University research laboratory. Subjects Domestic piglets. Interventions After induction of ventricular fibrillation, cardiopulmonary resuscitation was provided to ten piglets (10.7 ± 1.2 kg) for 18 mins as six 3-min epochs with no lean, 10% lean, or 20% lean to maintain aortic systolic pressure of 80–90 mm Hg. Because the mean force to attain 80–90 mm Hg was 18 kg in preliminary studies, the equivalent of 10% and 20% lean was provided by use of 1.8- and 3.6-kg weights on the chest. Measurements and Main Results Using a linear mixed-effect regression model to control for changes in cardiopulmonary resuscitation hemodynamics over time, mean right atrial diastolic pressure was 9 ± 0.6 mm Hg with no lean, 10 ± 0.3 mm Hg with 10% lean (p < .01), and 13 ± 0.3 mm Hg with 20% lean (p < .01), resulting in decreased coronary perfusion pressure with leaning. Microsphere-determined cardiac index and left ventricular myocardial blood flow were lower with 10% and 20% leaning throughout the 18 mins of cardiopulmonary resuscitation. Mean cardiac index decreased from 1.9 ± 0.2 L · M–2 · min–1 with no leaning to 1.6 ± 0.1 L · M–2 · min–1 with 10% leaning, and 1.4 ± 0.2 L · M–2 · min–1 with 20% leaning (p < .05). The myocardial blood flow decreased from 39 ± 7 mL · min–1 · 100 g–1 with no lean to 30 ± 6 mL · min–1 · 100 g–1 with 10% leaning and 26 ± 6 mL · min–1 · 100 g–1 with 20% leaning (p < .05). Conclusions Leaning of 10% to 20% (i.e., 1.8–3.6 kg) during cardiopulmonary resuscitation substantially decreased coronary

  18. Viewing a brief chest-compression-only CPR video improves bystander CPR performance and responsiveness in high school students: A cluster randomized trial.

    PubMed

    Beskind, Daniel L; Stolz, Uwe; Thiede, Rebecca; Hoyer, Riley; Burns, Whitney; Brown, Jeffrey; Ludgate, Melissa; Tiutan, Timothy; Shane, Romy; McMorrow, Deven; Pleasants, Michael; Panchal, Ashish R

    2016-07-01

    CPR training in schools is a public health initiative to improve out of hospital cardiac arrest (OHCA) survival. It is unclear whether brief video training in students improves CPR quality and responsiveness and skills retention. Determine if a brief video is as effective as classroom instruction for chest compression-only (CCO) CPR training in high school students. This was a prospective cluster-randomized controlled trial with three study arms: control (sham video), brief video (BV), and CCO-CPR class. Students were randomized and clustered based on their classrooms and evaluated using a standardized OHCA scenario measuring CPR quality (compression rate, depth, hands-off time) and responsiveness (calling 911, time to calling 911, starting compressions within 2min). Data was collected at baseline, post-intervention and 2 months. Generalized linear mixed models were used to analyze outcome data, accounting for repeated measures for each individual and clustering by class. 179 students (14-18 years) were consented in 7 classrooms (clusters). At post-intervention and 2 months, BV and CCO class students called 911 more frequently and sooner, started chest compressions earlier, and had improved chest compression rates and hands-off time compared to baseline. Chest compression depth improved significantly from baseline in the CCO class, but not in the BV group post-intervention and at 2 months. Brief CPR video training resulted in improved CPR quality and responsiveness in high school students. Compression depth only improved with traditional class training. This suggests brief educational interventions are beneficial to improve CPR responsiveness but psychomotor training is important for CPR quality. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  19. Tracheal Tube Position Shift During Infant Resuscitation by Chest Compression: A Simulation Comparison by Fixation Method and With or Without Cuff.

    PubMed

    Ueno, Takeshi; Komasawa, Nobuyasu; Majima, Nozomi; Mihara, Ryosuke; Minami, Toshiaki

    2016-04-01

    Tracheal tube placement during infant resuscitation is essential for definite airway protection. Accidental extubation due to tracheal tube displacement is a rare event, but it results in severe complications, especially in infants. The present study evaluated how infant tracheal tube displacement is affected by tape vs. tube holder fixation using a manikin. A tracheal tube with internal diameter of 3.5 mm was placed 10 cm from the gum ridge in an advanced life support (ALS) Baby(®) simulator (Laerdal, Stavanger, Norway). In the first trial, cuff pressure was set at 15, 20, and 25 cmH2O and trials were performed at each setting with no fixation, Durapore(®) (3M, St Paul, MN) tape fixation, Multipore(®) (3M) tape fixation, and Thomas(®) Tube Holder (Laerdal) fixation. After 5 min of chest compression, the tracheal tube shift was measured. In the second trial, we compared the tube shift by chest compression with or without cuff in the same way. Relative to no fixation, tracheal tube shift was significantly less in the Durapore, Multipore, and tube holder groups (p < 0.05) at all cuff settings. Of the three fixation methods, the tube holder showed significantly less shift (p < 0.05) relative to tape, regardless of the initial cuff pressure. The positional shift after chest compressions was significantly larger in the trials with cuff than in those without cuff in Durapore or Multipore fixation (p < 0.05), but did not in tube holder fixation. There is less tracheal tube displacement with tube holder fixation than with tape during continuous infant chest compression simulation. The tube cuff can contribute to the positional shift of the tube during infant chest compression. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Polymorphic phase transition mechanism of compressed coesite.

    PubMed

    Hu, Q Y; Shu, J-F; Cadien, A; Meng, Y; Yang, W G; Sheng, H W; Mao, H-K

    2015-03-20

    Silicon dioxide is one of the most abundant natural compounds. Polymorphs of SiO₂ and their phase transitions have long been a focus of great interest and intense theoretical and experimental pursuits. Here, compressing single-crystal coesite SiO₂ under hydrostatic pressures of 26-53 GPa at room temperature, we discover a new polymorphic phase transition mechanism of coesite to post-stishovite, by means of single-crystal synchrotron X-ray diffraction experiment and first-principles computational modelling. The transition features the formation of multiple previously unknown triclinic phases of SiO₂ on the transition pathway as structural intermediates. Coexistence of the low-symmetry phases results in extensive splitting of the original coesite X-ray diffraction peaks that appear as dramatic peak broadening and weakening, resembling an amorphous material. This work sheds light on the long-debated pressure-induced amorphization phenomenon of SiO₂, but also provides new insights into the densification mechanism of tetrahedrally bonded structures common in nature.

  1. Polymorphic phase transition mechanism of compressed coesite

    NASA Astrophysics Data System (ADS)

    Hu, Q. Y.; Shu, J.-F.; Cadien, A.; Meng, Y.; Yang, W. G.; Sheng, H. W.; Mao, H.-K.

    2015-03-01

    Silicon dioxide is one of the most abundant natural compounds. Polymorphs of SiO2 and their phase transitions have long been a focus of great interest and intense theoretical and experimental pursuits. Here, compressing single-crystal coesite SiO2 under hydrostatic pressures of 26-53 GPa at room temperature, we discover a new polymorphic phase transition mechanism of coesite to post-stishovite, by means of single-crystal synchrotron X-ray diffraction experiment and first-principles computational modelling. The transition features the formation of multiple previously unknown triclinic phases of SiO2 on the transition pathway as structural intermediates. Coexistence of the low-symmetry phases results in extensive splitting of the original coesite X-ray diffraction peaks that appear as dramatic peak broadening and weakening, resembling an amorphous material. This work sheds light on the long-debated pressure-induced amorphization phenomenon of SiO2, but also provides new insights into the densification mechanism of tetrahedrally bonded structures common in nature.

  2. GPU-accelerated compressed-sensing (CS) image reconstruction in chest digital tomosynthesis (CDT) using CUDA programming

    NASA Astrophysics Data System (ADS)

    Choi, Sunghoon; Lee, Haenghwa; Lee, Donghoon; Choi, Seungyeon; Shin, Jungwook; Jang, Woojin; Seo, Chang-Woo; Kim, Hee-Joung

    2017-03-01

    A compressed-sensing (CS) technique has been rapidly applied in medical imaging field for retrieving volumetric data from highly under-sampled projections. Among many variant forms, CS technique based on a total-variation (TV) regularization strategy shows fairly reasonable results in cone-beam geometry. In this study, we implemented the TV-based CS image reconstruction strategy in our prototype chest digital tomosynthesis (CDT) R/F system. Due to the iterative nature of time consuming processes in solving a cost function, we took advantage of parallel computing using graphics processing units (GPU) by the compute unified device architecture (CUDA) programming to accelerate our algorithm. In order to compare the algorithmic performance of our proposed CS algorithm, conventional filtered back-projection (FBP) and simultaneous algebraic reconstruction technique (SART) reconstruction schemes were also studied. The results indicated that the CS produced better contrast-to-noise ratios (CNRs) in the physical phantom images (Teflon region-of-interest) by factors of 3.91 and 1.93 than FBP and SART images, respectively. The resulted human chest phantom images including lung nodules with different diameters also showed better visual appearance in the CS images. Our proposed GPU-accelerated CS reconstruction scheme could produce volumetric data up to 80 times than CPU programming. Total elapsed time for producing 50 coronal planes with 1024×1024 image matrix using 41 projection views were 216.74 seconds for proposed CS algorithms on our GPU programming, which could match the clinically feasible time ( 3 min). Consequently, our results demonstrated that the proposed CS method showed a potential of additional dose reduction in digital tomosynthesis with reasonable image quality in a fast time.

  3. Effect of mattress and bed frame deflection on real chest compression depth measured with two CPR sensors.

    PubMed

    Sainio, Marko; Hellevuo, Heidi; Huhtala, Heini; Hoppu, Sanna; Eilevstjønn, Joar; Tenhunen, Jyrki; Olkkola, Klaus T

    2014-06-01

    Implementation of chest compression (CC) feedback devices with a single force and deflection sensor (FDS) may improve the quality of CPR. However, CC depth may be overestimated if the patient is on a compliant surface. We have measured the true CC depth during in-hospital CPR using two FDSs on different bed and mattress types. This prospective observational study was conducted at Tampere University Hospital between August 2011 and September 2012. During in-hospital CPR one FDS was placed between the rescuer's hand and the patient's chest, with the second attached to the backboard between the patient's back and the mattress. The real CC depth was calculated as the difference between the total depth from upper FDS to lower FDS. Ten cardiac arrests on three different bed and mattress types yielded 10,868 CCs for data analyses. The mean (SD) mattress/bed frame effect was 12.8 (4) mm on a standard hospital bed with a gel mattress, 12.4 (4) mm on an emergency room stretcher with a thin gel mattress and 14.1 (3) mm on an ICU bed with an emptied air mattress. The proportion of CCs with an adequate depth (≥50 mm) decreased on all mattress types after compensating for the mattress/bed frame effect from 94 to 64%, 98 to 76% and 91 to 17%, in standard hospital bed, emergency room stretcher and ICU bed, respectively (p<0.001). The use of FDS without real-time correction for deflection may result in CC depth not reaching the recommended depth of 50 mm. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  4. Use of a Real-Time Training Software (Laerdal QCPR®) Compared to Instructor-Based Feedback for High-Quality Chest Compressions Acquisition in Secondary School Students: A Randomized Trial.

    PubMed

    Cortegiani, Andrea; Russotto, Vincenzo; Montalto, Francesca; Iozzo, Pasquale; Meschis, Roberta; Pugliesi, Marinella; Mariano, Dario; Benenati, Vincenzo; Raineri, Santi Maurizio; Gregoretti, Cesare; Giarratano, Antonino

    2017-01-01

    High-quality chest compressions are pivotal to improve survival from cardiac arrest. Basic life support training of school students is an international priority. The aim of this trial was to assess the effectiveness of a real-time training software (Laerdal QCPR®) compared to a standard instructor-based feedback for chest compressions acquisition in secondary school students. After an interactive frontal lesson about basic life support and high quality chest compressions, 144 students were randomized to two types of chest compressions training: 1) using Laerdal QCPR® (QCPR group- 72 students) for real-time feedback during chest compressions with the guide of an instructor who considered software data for students' correction 2) based on standard instructor-based feedback (SF group- 72 students). Both groups had a minimum of a 2-minute chest compressions training session. Students were required to reach a minimum technical skill level before the evaluation. We evaluated all students at 7 days from the training with a 2-minute chest compressions session. The primary outcome was the compression score, which is an overall measure of chest compressions quality calculated by the software expressed as percentage. 125 students were present at the evaluation session (60 from QCPR group and 65 from SF group). Students in QCPR group had a significantly higher compression score (median 90%, IQR 81.9-96.0) compared to SF group (median 67%, IQR 27.7-87.5), p = 0.0003. Students in QCPR group performed significantly higher percentage of fully released chest compressions (71% [IQR 24.5-99.0] vs 24% [IQR 2.5-88.2]; p = 0.005) and better chest compression rate (117.5/min [IQR 106-123.5] vs 125/min [115-135.2]; p = 0.001). In secondary school students, a training for chest compressions based on a real-time feedback software (Laerdal QCPR®) guided by an instructor is superior to instructor-based feedback training in terms of chest compression technical skill acquisition. Australian

  5. Use of a Real-Time Training Software (Laerdal QCPR®) Compared to Instructor-Based Feedback for High-Quality Chest Compressions Acquisition in Secondary School Students: A Randomized Trial

    PubMed Central

    Russotto, Vincenzo; Montalto, Francesca; Iozzo, Pasquale; Meschis, Roberta; Pugliesi, Marinella; Mariano, Dario; Benenati, Vincenzo; Raineri, Santi Maurizio; Gregoretti, Cesare; Giarratano, Antonino

    2017-01-01

    High-quality chest compressions are pivotal to improve survival from cardiac arrest. Basic life support training of school students is an international priority. The aim of this trial was to assess the effectiveness of a real-time training software (Laerdal QCPR®) compared to a standard instructor-based feedback for chest compressions acquisition in secondary school students. After an interactive frontal lesson about basic life support and high quality chest compressions, 144 students were randomized to two types of chest compressions training: 1) using Laerdal QCPR® (QCPR group– 72 students) for real-time feedback during chest compressions with the guide of an instructor who considered software data for students’ correction 2) based on standard instructor-based feedback (SF group– 72 students). Both groups had a minimum of a 2-minute chest compressions training session. Students were required to reach a minimum technical skill level before the evaluation. We evaluated all students at 7 days from the training with a 2-minute chest compressions session. The primary outcome was the compression score, which is an overall measure of chest compressions quality calculated by the software expressed as percentage. 125 students were present at the evaluation session (60 from QCPR group and 65 from SF group). Students in QCPR group had a significantly higher compression score (median 90%, IQR 81.9–96.0) compared to SF group (median 67%, IQR 27.7–87.5), p = 0.0003. Students in QCPR group performed significantly higher percentage of fully released chest compressions (71% [IQR 24.5–99.0] vs 24% [IQR 2.5–88.2]; p = 0.005) and better chest compression rate (117.5/min [IQR 106–123.5] vs 125/min [115–135.2]; p = 0.001). In secondary school students, a training for chest compressions based on a real-time feedback software (Laerdal QCPR®) guided by an instructor is superior to instructor-based feedback training in terms of chest compression technical skill

  6. Comparison of the Pentax Airwayscope, Glidescope Video Laryngoscope, and Macintosh Laryngoscope During Chest Compression According to Bed Height

    PubMed Central

    Kim, Wonhee; Lee, Yoonje; Kim, Changsun; Lim, Tae Ho; Oh, Jaehoon; Kang, Hyunggoo; Lee, Sanghyun

    2016-01-01

    Abstract We aimed to investigate whether bed height affects intubation performance in the setting of cardiopulmonary resuscitation and which type of laryngoscope shows the best performance at each bed height. A randomized crossover manikin study was conducted. Twenty-one participants were enrolled, and they were randomly allocated to 2 groups: group A (n = 10) and group B (n = 11). The participants underwent emergency endotracheal intubation (ETI) using the Airwayscope (AWS), Glidescope video laryngoscope, and Macintosh laryngoscope in random order while chest compression was performed. Each ETI was conducted at 2 levels of bed height (minimum bed height: 68.9 cm and maximum bed height: 101.3 cm). The primary outcomes were the time to intubation (TTI) and the success rate of ETI. The P value for statistical significance was set at 0.05 and 0.017 in post-hoc test. The success rate of ETI was always 100% regardless of the type of laryngoscope or the bed height. TTI was not significantly different between the 2 bed heights regardless of the type of laryngoscope (all P > 0.05). The time for AWS was the shortest among the 3 laryngoscopes at both bed heights (13.7 ± 3.6 at the minimum bed height and 13.4 ± 4.7 at the maximum bed height) (all P < 0.017). The TTI of Glidescope video laryngoscope was not significantly shorter than that of Macintosh laryngoscope at the minimum height (17.6 ± 4.0 vs 19.6 ± 4.8; P = 0.02). The bed height, whether adjusted to the minimum or maximum setting, did not affect intubation performance. In addition, regardless of the bed height, the intubation time with the video laryngoscopes, especially AWS, was significantly shorter than that with the direct laryngoscope during chest compression. PMID:26844477

  7. Comparison of the Pentax Airwayscope, Glidescope Video Laryngoscope, and Macintosh Laryngoscope During Chest Compression According to Bed Height.

    PubMed

    Kim, Wonhee; Lee, Yoonje; Kim, Changsun; Lim, Tae Ho; Oh, Jaehoon; Kang, Hyunggoo; Lee, Sanghyun

    2016-02-01

    We aimed to investigate whether bed height affects intubation performance in the setting of cardiopulmonary resuscitation and which type of laryngoscope shows the best performance at each bed height.A randomized crossover manikin study was conducted. Twenty-one participants were enrolled, and they were randomly allocated to 2 groups: group A (n = 10) and group B (n = 11). The participants underwent emergency endotracheal intubation (ETI) using the Airwayscope (AWS), Glidescope video laryngoscope, and Macintosh laryngoscope in random order while chest compression was performed. Each ETI was conducted at 2 levels of bed height (minimum bed height: 68.9  cm and maximum bed height: 101.3 cm). The primary outcomes were the time to intubation (TTI) and the success rate of ETI. The P value for statistical significance was set at 0.05 and 0.017 in post-hoc test.The success rate of ETI was always 100% regardless of the type of laryngoscope or the bed height. TTI was not significantly different between the 2 bed heights regardless of the type of laryngoscope (all P > 0.05). The time for AWS was the shortest among the 3 laryngoscopes at both bed heights (13.7  ±  3.6 at the minimum bed height and 13.4  ±  4.7 at the maximum bed height) (all P < 0.017). The TTI of Glidescope video laryngoscope was not significantly shorter than that of Macintosh laryngoscope at the minimum height (17.6  ±  4.0 vs 19.6  ±  4.8; P = 0.02).The bed height, whether adjusted to the minimum or maximum setting, did not affect intubation performance. In addition, regardless of the bed height, the intubation time with the video laryngoscopes, especially AWS, was significantly shorter than that with the direct laryngoscope during chest compression.

  8. Effect of Emergency Department Mattress Compressibility on Chest Compression Depth Using a Standardized Cardiopulmonary Resuscitation Board, a Slider Transfer Board, and a Flat Spine Board: A Simulation-Based Study.

    PubMed

    Cheng, Adam; Belanger, Claudia; Wan, Brandi; Davidson, Jennifer; Lin, Yiqun

    2017-07-10

    Cardiopulmonary resuscitation (CPR) performed on a mattress decreases effective chest compression depth. Using a CPR board partially attenuates mattress compressibility. We aimed to determine the effect of a CPR board, a slider transfer board, a CPR board with a slider transfer board, and a flat spine board on chest compression depth with a mannequin placed on an emergency department mattress. The study used a cross-over study design. The CPR-certified healthcare providers performed 2 minutes of compressions on a mannequin in five conditions, an emergency department mattress with: (a) no hard surface, (b) a CPR board, (c) a slider transfer board, (d) a CPR board and slider transfer board, and (e) a flat spine board. Compression depths were measured from two sources for each condition: (a) an internal device measuring sternum-to-spine compression and (b) an external device measuring sternum-to-spine compression plus mattress compression. The difference of the two measures (ie, depleted compression depth) was summarized and compared between conditions. A total of 10,203 individual compressions from 10 participants were analyzed. The mean depleted compression depths (percentage depletion) secondary to mattress effect were the following: 23.6 mm (29.7%) on a mattress only, 13.7 mm (19.5%) on a CPR board, 16.9 mm (23.1%) on a slider transfer board, 11.9 mm (17.3%) on a slider transfer board plus backboard, and 10.3 mm (15.4%) on a flat spine board. The differences in percentage depletion across conditions were statistically significant. Cardiopulmonary resuscitation providers should use a CPR board and slider transfer board or a flat spine board alone because these conditions are associated with the smallest amount of mattress compressibility.

  9. Comparative Effectiveness of Emergency Resuscitative Thoracotomy versus Closed Chest Compressions among Patients with Critical Blunt Trauma: A Nationwide Cohort Study in Japan

    PubMed Central

    Suzuki, Kodai; Inoue, Shigeaki; Morita, Seiji; Watanabe, Nobuo; Shintani, Ayumi; Inokuchi, Sadaki; Ogura, Shinji

    2016-01-01

    Background Although emergency resuscitative thoracotomy is performed as a salvage maneuver for critical blunt trauma patients, evidence supporting superior effectiveness of emergency resuscitative thoracotomy compared to conventional closed-chest compressions remains insufficient. The objective of this study was to investigate whether emergency resuscitative thoracotomy at the emergency department or in the operating room was associated with favourable outcomes after blunt trauma and to compare its effectiveness with that of closed-chest compressions. Methods This was a retrospective nationwide cohort study. Data were obtained from the Japan Trauma Data Bank for the period between 2004 and 2012. The primary and secondary outcomes were patient survival rates 24 h and 28 d after emergency department arrival. Statistical analyses were performed using multivariable generalized mixed-effects regression analysis. We adjusted for the effects of different hospitals by introducing random intercepts in regression analysis to account for the differential quality of emergency resuscitative thoracotomy at hospitals where patients in cardiac arrest were treated. Sensitivity analyses were performed using propensity score matching. Results In total, 1,377 consecutive, critical blunt trauma patients who received cardiopulmonary resuscitation in the emergency department or operating room were included in the study. Of these patients, 484 (35.1%) underwent emergency resuscitative thoracotomy and 893 (64.9%) received closed-chest compressions. Compared to closed-chest compressions, emergency resuscitative thoracotomy was associated with lower survival rate 24 h after emergency department arrival (4.5% vs. 17.5%, respectively, P < 0.001) and 28 d after arrival (1.2% vs. 6.0%, respectively, P < 0.001). Multivariable generalized mixed-effects regression analysis with and without a propensity score-matched dataset revealed that the odds ratio for an unfavorable survival rate after 24 h

  10. Are chest compressions safe for the patient reconstructed with sternal plates? Evaluating the safety of cardiopulmonary resuscitation using a human cadaveric model

    PubMed Central

    2010-01-01

    Background Plate and screw fixation is a recent addition to the sternal wound treatment armamentarium. Patients undergoing cardiac and major vascular surgery have a higher risk of postoperative arrest than other elective patients. Those who undergo sternotomy for either cardiac or major vascular procedures are at a higher risk of postoperative arrest. Sternal plate design allows quick access to the mediastinum facilitating open cardiac massage, but chest compressions are the mainstay of re-establishing cardiac output in the event of arrest. The response of sternal plates and the chest wall to compressions when plated has not been studied. The safety of performing this maneuver is unknown. This study intends to demonstrate compressions are safe after sternal plating. Methods We investigated the effect of chest compressions on the plated sternum using a human cadaveric model. Cadavers were plated, an arrest was simulated, and an experienced physician performed a simulated resuscitation. Intrathoracic pressure was monitored throughout to ensure the plates encountered an appropriate degree of force. The hardware and viscera were evaluated for failure and trauma respectively. Results No hardware failure or obvious visceral trauma was observed. Rib fractures beyond the boundaries of the plates were noted but the incidence was comparable to control and to the fracture incidence after resuscitation previously cited in the literature. Conclusions From this work we believe chest compressions are safe for the patient with sternal plates when proper plating technique is used. We advocate the use of this life-saving maneuver as part of an ACLS resuscitation in the event of an arrest for rapidly re-establishing circulation. PMID:20718981

  11. Should PEEP Titration Be Based on Chest Mechanics in Patients With ARDS?

    PubMed

    Kallet, Richard H

    2016-06-01

    Functional residual capacity (FRC) is essentially the alveolar volume and a determinant of both oxygenation and respiratory system compliance (CRS). ARDS decreases FRC, and sufficient PEEP restores FRC; thus, assessments of PEEP by its impact on oxygenation and CRS are intimately linked. PEEP also can ameliorate or aggravate ventilator-induced lung injury. Therefore, it can be argued that PEEP should be titrated primarily by its impact on CRS The pro position argues that the heterogeneous nature of lung injury and its unique presentation in individual patients results in an uncoupling between oxygenation and CRS Therefore, relying upon oxygenation alone may enhance lung injury and mortality risk, particularly in those with severe ARDS. The con argument is that the preponderance of preclinical and clinical evidence suggests that a relatively narrow range of PEEP is required to manage all but the most severe cases of ARDS. In addition, pathological alterations in chest wall compliance confuse the interpretation of chest mechanics. Moreover, ambiguities and technical limitations in advanced techniques, such as esophageal manometry and pressure-volume curves, add a layer of complexity that renders its broader application in all ARDS patients both impractical and unnecessary. Whether sophisticated monitoring of chest mechanics in severe ARDS might improve outcomes further is open to question and should be studied further. However, it is highly improbable that we will ever discover a PEEP strategy that optimizes all aspects of cardiorespiratory function and chest mechanics for individual patients suffering from ARDS. Copyright © 2016 by Daedalus Enterprises.

  12. Compression mechanisms in the plasma focus pinch

    NASA Astrophysics Data System (ADS)

    Lee, S.; Saw, S. H.; Ali, Jalil

    2017-03-01

    The compression of the plasma focus pinch is a dynamic process, governed by the electrodynamics of pinch elongation and opposed by the negative rate of change of current dI/dt associated with the current dip. The compressibility of the plasma is influenced by the thermodynamics primarily the specific heat ratio; with greater compressibility as the specific heat ratio γ reduces with increasing degree of freedom f of the plasma ensemble due to ionization energy for the higher Z (atomic number) gases. The most drastic compression occurs when the emitted radiation of a high-Z plasma dominates the dynamics leading in extreme cases to radiative collapse which is terminated only when the compressed density is sufficiently high for the inevitable self-absorption of radiation to occur. We discuss the central pinch equation which contains the basic electrodynamic terms with built-in thermodynamic factors and a dQ/dt term; with Q made up of a Joule heat component and absorption-corrected radiative terms. Deuterium is considered as a thermodynamic reference (fully ionized perfect gas with f = 3) as well as a zero-radiation reference (bremsstrahlung only; with radiation power negligible compared with electrodynamic power). Higher Z gases are then considered and regimes of thermodynamic enhancement of compression are systematically identified as are regimes of radiation-enhancement. The code which incorporates all these effects is used to compute pinch radius ratios in various gases as a measure of compression. Systematic numerical experiments reveal increasing severity in radiation-enhancement of compressions as atomic number increases. The work progresses towards a scaling law for radiative collapse and a generalized specific heat ratio incorporating radiation.

  13. High-frequency and low-frequency chest compression: effects on lung water secretion, mucus transport, heart rate, and blood pressure using a trapezoidal source pressure waveform.

    PubMed

    O'Clock, George D; Lee, Yong Wan; Lee, Jongwong; Warwick, Warren J

    2012-01-01

    High-frequency chest compression (HFCC), using an appropriate source (pump) waveform for frequencies at or above 3 Hz, can enhance pulmonary clearance for patients with cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). Using a trapezoidal HFCC source pressure waveform, secretion of water from epithelial tissue and transport of mucus through lung airways can be enhanced for patients with CF and COPD. At frequencies below 3 Hz, low-frequency chest compression (LFCC) appears to have a significant impact on the cardiovascular system. For a trapezoidal source pressure waveform at frequencies close to 1 Hz, LFCC produces amplitude or intensity variations in various components of the electrocardiogram time-domain waveform, produces changes at very low frequencies associated with the electrocardiogram frequency spectra (indicating enhanced parasympathetic nervous system activity), and promotes a form of heart rate synchronization. It appears that LFCC can also provide additional cardiovascular benefits by reducing peak and average systolic and diastolic blood pressure for patients with hypertension.

  14. Pericardial tear as a consequence of cardiopulmonary resuscitation (CPR) involving chest compression: a report of two postmortem cases of acute type A aortic dissection with hemopericardium.

    PubMed

    Okuda, Takahisa; Takanari, Hiroki; Shiotani, Seiji; Hayakawa, Hideyuki; Ohno, Youkichi; Fowler, David R

    2015-05-01

    We present two cases of a pericardial tear as a consequence of cardiopulmonary resuscitation involving chest compressions in fatal acute type A aortic dissection (AoD) with hemopericardium. For each case, postmortem computed tomography revealed a hematoma in the false lumen of the ascending aorta with a slight hemopericardium and a large left hemothorax, as well as focal pericardial dimpling and discontinuity around the left ventricle. At autopsy, we confirmed a convex lens-shape gaping pericardial tear at the left posterolateral site of the pericardium and a massive volume of bloody fluid in the left thoracic cavity. It has been hypothesized that the pericardium ruptured due to chest compressions during resuscitation in these cases of acute type A AoD with hemopericardium and that intrapericardial blood leakage through the pericardial tear resulted in a hemothorax. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  15. Inelastic deformation mechanisms in a transverse MMC lamina under compression

    NASA Technical Reports Server (NTRS)

    Newaz, Golam M.; Majumdar, Bhaskar S.

    1992-01-01

    An investigation was undertaken to study the inelastic deformation mechanisms in (90)(sub 8) Ti 15-3/SCS-6 lamina subjected to pure compression. Both mechanical behavior and microstructural evaluation were undertaken at room temperature, 538 and 650 C. Results indicate that mechanical response and deformation characteristics are significantly different in monotonic tension and compression. The inelastic deformation mechanisms in compression are controlled by radial fiber fracture, matrix plasticity and fiber-matrix debonding. The radial fiber fracture is a new damage mode observed for metal-matrix composites (MMC).

  16. Inelastic deformation mechanisms in a transverse MMC lamina under compression

    NASA Technical Reports Server (NTRS)

    Newaz, Golam M.; Majumdar, Bhaskar S.

    1992-01-01

    An investigation was undertaken to study the inelastic deformation mechanisms in (90)(sub 8) Ti 15-3/SCS-6 lamina subjected to pure compression. Both mechanical behavior and microstructural evaluation were undertaken at room temperature, 538 and 650 C. Results indicate that mechanical response and deformation characteristics are significantly different in monotonic tension and compression. The inelastic deformation mechanisms in compression are controlled by radial fiber fracture, matrix plasticity and fiber-matrix debonding. The radial fiber fracture is a new damage mode observed for metal-matrix composites (MMC).

  17. Continuous on-line measurements of respiratory system, lung and chest wall mechanics during mechanic ventilation.

    PubMed

    Kárason, S; Søndergaard, S; Lundin, S; Stenqvist, O

    2001-08-01

    We present a concept of on-line, manoeuvre-free monitoring of respiratory mechanics during dynamic conditions, displaying calculated alveolar pressure/volume curves continuously and separating lung and chest wall mechanics. Prospective observational study. Intensive care unit of a university hospital. Ten ventilator-treated patients with acute lung injury. Different positive end-expiratory pressure (PEEP) and tidal volumes, low flow inflation. Previously validated methods were used to present a single-value dynostatic compliance for the whole breath and a dynostatic volume-dependent initial, middle and final compliance within the breath. A high individual variation of respiratory mechanics was observed. Reproducibility of repeated measurements was satisfactory (coefficients of variations for dynostatic volume-dependent compliance: < or =9.2% for total respiratory system, < or =18% for lung). Volume-dependent compliance showed a statistically significant pattern of successively decreasing compliance from the initial segment through the middle and final parts within each breath at all respiratory settings. This pattern became more prominent with increasing PEEP and tidal volume, indicating a greater distension of alveoli. No lower inflection point (LIP) was seen in patients with respiratory rate 20/min and PEEP at 4 cmH2O. A trial with low flow inflation in four of the patients showed formation of a LIP in three of them and an upper inflection in one. The monitoring concept revealed a constant pattern of successively decreasing compliance within each breath, which became more prominent with increasing PEEP and tidal volume. The monitoring concept offers a simple and reliable method of monitoring respiratory mechanics during ongoing ventilator treatment.

  18. Clinical study on VATS combined mechanical ventilation treatment of ARDS secondary to severe chest trauma

    PubMed Central

    Qi, Yongjun

    2016-01-01

    The aim of the study was to investigate the clinical effects of microinvasive video-assisted thoracoscopic surgery (VATS) combined with mechanical ventilation in the treatment of acute respiratory distress syndrome (ARDS) secondary to severe chest trauma. A total of 62 patients with ARDS secondary to severe chest trauma were divided into the observation and control groups. The patients in the observation groups were treated with VATS combined with early mechanical ventilation while patients in the control group were treated using routine open thoracotomy combined with early mechanical ventilation. Compared to the controls, the survival rate of the observation group was significantly higher. The average operation time of the observation group was significantly shorter than that of the control group, and the incidence of complications in the perioperative period of the observation group was significantly lower than that of the control group (p<0.05). The average application time of the observation group was significantly shorter than that of the control group, and the incidence of ventilator-associated complications was significantly lower than that of the control group (p<0.05). In conclusion, a reasonable understanding of the indications and contraindications of VATS, combined with early mechanical treatment significantly improved the success rate of the treatment of ARDS patients secondary to severe chest trauma and reduced the complications. PMID:27446317

  19. Improvement of lay rescuer chest compressions with a novel audiovisual feedback device : A randomized trial.

    PubMed

    Wutzler, A; von Ulmenstein, S; Bannehr, M; Völk, K; Förster, J; Storm, C; Haverkamp, W

    2017-04-04

    Bystander actions and skills determine among others the outcome of out-of-hospital cardiac arrest. However, the depth and rate of chest compressions (CC) are difficult to estimate for laypeople and poor CC quality may result. Our study aimed to evaluate the impact of a new feedback device on CC performance by laypeople. The percentage of CC with both correct rate and correct depth of all CC served as primary endpoint. Forty-eight subjects with no medical background performed 2 min of CC on a manikin with and without a novel feedback device (TrueCPR™, Physio-Control, Redmond, Wash.). The device uses a novel, non-accelerometer-based technology. Participants were randomized into two groups. Group 1 performed a 2-min CC trial first with audiovisual feedback followed by a trial with no feedback information, while group 2 performed the task in reverse order. The absolute percentage of CC with correct rate and depth was significantly higher with the use of the device (59 ± 34% vs. 15 ± 21%, p < 0.0001). The longest interval without correct CC was significantly decreased (76.5 s vs. 27.5 s, p < 0.0001). The quality of CC carried out by laypeople is significantly improved with the use of a new feedback device. The device may be useful for cardiopulmonary resuscitation (CPR) by laypeople and for educational purposes.

  20. A comparison of video review and feedback device measurement of chest compressions quality during pediatric cardiopulmonary resuscitation.

    PubMed

    Hsieh, Ting-Chang; Wolfe, Heather; Sutton, Robert; Myers, Sage; Nadkarni, Vinay; Donoghue, Aaron

    2015-08-01

    To describe chest compression (CC) rate, depth, and leaning during pediatric cardiopulmonary resuscitation (CPR) as measured by two simultaneous methods, and to assess the accuracy and reliability of video review in measuring CC quality. Resuscitations in a pediatric emergency department are videorecorded for quality improvement. Patients aged 8-18 years receiving CPR under videorecording were eligible for inclusion. CPR was recorded by a pressure/accelerometer feedback device and tabulated in 30-s epochs of uninterrupted CC. Investigators reviewed videorecorded CPR and measured rate, depth, and release by observation. Raters categorized epochs as 'meeting criteria' if 80% of CCs in an epoch were done with appropriate depth (>45 mm) and/or release (<2.5 kg leaning). Comparison between device measurement and video was made by Spearman's ρ for rate and by κ statistic for depth and release. Interrater reliability for depth and release was measured by κ statistic. Five patients underwent videorecorded CPR using the feedback device. 97 30-s epochs of CCs were analyzed. CCs met criteria for rate in 74/97 (76%) of epochs; depth in 38/97 (39%); release in 82/97 (84%). Agreement between video and feedback device for rate was good (ρ = 0.77); agreement was poor for depth and release (κ 0.04-0.41). Interrater reliability for depth and release measured by video was poor (κ 0.04-0.49). Video review measured CC rate accurately; depth and release were not reliably or accurately assessed by video. Future research should focus on the optimal combination of methods for measuring CPR quality. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  1. Effect of listening to Nellie the Elephant during CPR training on performance of chest compressions by lay people: randomised crossover trial

    PubMed Central

    Rawlins, L; Williams, J; Hallam, P

    2009-01-01

    Objectives To determine whether listening to music during cardiopulmonary resuscitation (CPR) training increases the proportion of lay people delivering chest compressions of 100 per minute. Design Prospective randomised crossover trial. Setting Large UK university. Participants 130 volunteers (81 men) recruited on an opportunistic basis. Exclusion criteria included age under 18, trained health professionals, and cardiopulmonary resuscitation (CPR) training within the past three months. Interventions Volunteers performed three sequences of one minute of continuous chest compressions on a skill meter resuscitation manikin accompanied by no music, repeated choruses of Nellie the Elephant (Nellie), and That’s the Way (I like it) (TTW) according to a pre-randomised order. Main outcome measures Rate of chest compressions delivered (primary outcome), depth of compressions, proportion of incorrect compressions, and type of error. Results Median (interquartile range) compression rates were 110 (93-119) with no music, 105 (98-107) with Nellie, and 109 (103-110) with TTW. There were significant differences within groups between Nellie v no music and Nellie v TTW (P<0.001) but not no music v TTW (P=0.055). A compression rate of between 95 and 105 was achieved with no music, Nellie, and TTW for 15/130 (12%), 42/130 (32%), and 12/130 (9%) attempts, respectively. Differences in proportions were significant for Nellie v no music and Nellie v TTW (P<0.001) but not for no music v TTW (P=0.55). Relative risk for a compression rate between 95 and 105 was 2.8 (95% confidence interval 1.66 to 4.80) for Nellie v no music, 0.8 (0.40 to 1.62) for TTW v no music, and 3.5 (1.97 to 6.33) for Nellie v TTW. The number needed to treat for listening to Nellie v no music was 5 (4 to 10)—that is, the number of cardiac arrests required during which lay responders listen to Nellie to facilitate one patient receiving compressions at the correct rate (v no music) would be between four and 10. A

  2. Effect of listening to Nellie the Elephant during CPR training on performance of chest compressions by lay people: randomised crossover trial.

    PubMed

    Rawlins, L; Woollard, M; Williams, J; Hallam, P

    2009-12-11

    To determine whether listening to music during cardiopulmonary resuscitation (CPR) training increases the proportion of lay people delivering chest compressions of 100 per minute. Prospective randomised crossover trial. Large UK university. 130 volunteers (81 men) recruited on an opportunistic basis. Exclusion criteria included age under 18, trained health professionals, and cardiopulmonary resuscitation (CPR) training within the past three months. Volunteers performed three sequences of one minute of continuous chest compressions on a skill meter resuscitation manikin accompanied by no music, repeated choruses of Nellie the Elephant (Nellie), and That's the Way (I like it) (TTW) according to a pre-randomised order. Rate of chest compressions delivered (primary outcome), depth of compressions, proportion of incorrect compressions, and type of error. Median (interquartile range) compression rates were 110 (93-119) with no music, 105 (98-107) with Nellie, and 109 (103-110) with TTW. There were significant differences within groups between Nellie v no music and Nellie v TTW (P<0.001) but not no music v TTW (P=0.055). A compression rate of between 95 and 105 was achieved with no music, Nellie, and TTW for 15/130 (12%), 42/130 (32%), and 12/130 (9%) attempts, respectively. Differences in proportions were significant for Nellie v no music and Nellie v TTW (P<0.001) but not for no music v TTW (P=0.55). Relative risk for a compression rate between 95 and 105 was 2.8 (95% confidence interval 1.66 to 4.80) for Nellie v no music, 0.8 (0.40 to 1.62) for TTW v no music, and 3.5 (1.97 to 6.33) for Nellie v TTW. The number needed to treat for listening to Nellie v no music was 5 (4 to 10)-that is, the number of cardiac arrests required during which lay responders listen to Nellie to facilitate one patient receiving compressions at the correct rate (v no music) would be between four and 10. A greater proportion of compressions were too shallow when participants listened to Nellie

  3. Powder compression mechanics of spray-dried lactose nanocomposites.

    PubMed

    Hellrup, Joel; Nordström, Josefina; Mahlin, Denny

    2017-02-25

    The aim of this study was to investigate the structural impact of the nanofiller incorporation on the powder compression mechanics of spray-dried lactose. The lactose was co-spray-dried with three different nanofillers, that is, cellulose nanocrystals, sodium montmorillonite and fumed silica, which led to lower micron-sized nanocomposite particles with varying structure and morphology. The powder compression mechanics of the nanocomposites and physical mixtures of the neat spray-dried components were evaluated by a rational evaluation method with compression analysis as a tool, using the Kawakita equation and the Shapiro-Konopicky-Heckel equation. Particle rearrangement dominated the initial compression profiles due to the small particle size of the materials. The strong contribution of particle rearrangement in the materials with fumed silica continued throughout the whole compression profile, which prohibited an in-depth material characterization. However, the lactose/cellulose nanocrystals and the lactose/sodium montmorillonite nanocomposites demonstrated high yield pressure compared with the physical mixtures indicating increased particle hardness upon composite formation. This increase has likely to do with a reinforcement of the nanocomposite particles by skeleton formation of the nanoparticles. In summary, the rational evaluation of mechanical properties done by applying powder compression analysis proved to be a valuable tool for mechanical evaluation for this type of spray-dried composite materials, unless they demonstrate particle rearrangement throughout the whole compression profile.

  4. A mechanical chest compressor closed-loop controller with an effective trade-off between blood flow improvement and ribs fracture reduction.

    PubMed

    Zhang, Guang; Wu, Taihu; Song, Zhenxing; Wang, Haitao; Lu, Hengzhi; Wang, Yalin; Wang, Dan; Chen, Feng

    2015-06-01

    Chest compression (CC) is a significant emergency medical procedure for maintaining circulation during cardiac arrest. Although CC produces the necessary blood flow for patients with heart arrest, improperly deep CC will contribute significantly to the risk of chest injury. In this paper, an optimal CC closed-loop controller for a mechanical chest compressor (OCC-MCC) was developed to provide an effective trade-off between the benefit of improved blood perfusion and the risk of ribs fracture. The trade-off performance of the OCC-MCC during real automatic mechanical CCs was evaluated by comparing the OCC-MCC and the traditional mechanical CC method (TMCM) with a human circulation hardware model based on hardware simulations. A benefit factor (BF), risk factor (RF) and benefit versus risk index (BRI) were introduced in this paper for the comprehensive evaluation of risk and benefit. The OCC-MCC was developed using the LabVIEW control platform and the mechanical chest compressor (MCC) controller. PID control is also employed by MCC for effective compression depth regulation. In addition, the physiological parameters model for MCC was built based on a digital signal processor for hardware simulations. A comparison between the OCC-MCC and TMCM was then performed based on the simulation test platform which is composed of the MCC, LabVIEW control platform, physiological parameters model for MCC and the manikin. Compared with the TMCM, the OCC-MCC obtained a better trade-off and a higher BRI in seven out of a total of nine cases. With a higher mean value of cardiac output (1.35 L/min) and partial pressure of end-tidal CO2 (15.7 mmHg), the OCC-MCC obtained a larger blood flow and higher BF than TMCM (5.19 vs. 3.41) in six out of a total of nine cases. Although it is relatively difficult to maintain a stable CC depth when the chest is stiff, the OCC-MCC is still superior to the TMCM for performing safe and effective CC during CPR. The OCC-MCC is superior to the TMCM in

  5. Chest physiotherapy for preventing morbidity in babies being extubated from mechanical ventilation.

    PubMed

    Flenady, V J; Gray, P H

    2002-01-01

    Chest physiotherapy has been used to clear secretions and help lung ventilation in newborns who have needed mechanical ventilation for respiratory problems. However concerns about the safety of some forms of chest physiotherapy have been expressed. To assess the effects of active chest physiotherapy on babies being extubated from mechanical ventilation for neonatal respiratory failure. The standard search strategy of the Cochrane Neonatal Review Group was used. This included searches of electronic databases: Oxford Database of Perinatal Trials; Cochrane Controlled Trials Register (Cochrane Library Issue 4 2001); MEDLINE (1966-2001); and CINAHL (1982-2001), previous reviews including cross references, abstracts, conferences, symposia proceedings, expert informants and journal hand searching mainly in the English language. All trials utilising random or quasi-random patient allocation, in which active chest physiotherapy was compared with non-active techniques (eg positioning and suction alone) or no intervention in the periextubation period. Assessment of methodological quality and extraction of data for each included trial was undertaken independently by the authors. Data were extracted for the primary outcomes of postextubation lobar collapse, use of reintubation, duration of oxygen therapy, intracranial haemorrhage, cerebral cystic lesions, long term neurosensory impairment and death. Subgroup analysis was performed on different treatment frequencies and gestational age less than 32 weeks. Meta-analysis was conducted using a fixed effects model. Results are presented as relative risk (RR), risk difference (RD) and number needed to treat (NNT) for categorical data and mean difference (MD) for data measured on a continuous scale. All outcomes are reported with the use of 95% confidence intervals. In this review of four trials, two of which were carried out 15 & 23 years ago, no clear benefit of periextubation active chest physiotherapy can be seen. Active chest

  6. Tension pneumothorax secondary to automatic mechanical compression decompression device.

    PubMed

    Hutchings, A C; Darcy, K J; Cumberbatch, G L A

    2009-02-01

    The details are presented of the first published case of a tension pneumothorax induced by an automatic compression-decompression (ACD) device during cardiac arrest. An elderly patient collapsed with back pain and, on arrival of the crew, was in pulseless electrical activity (PEA) arrest. He was promptly intubated and correct placement of the endotracheal tube was confirmed by noting equal air entry bilaterally and the ACD device applied. On the way to the hospital he was noted to have absent breath sounds on the left without any change in the position of the endotracheal tube. Needle decompression of the left chest caused a hiss of air but the patient remained in PEA. Intercostal drain insertion in the emergency department released a large quantity of air from his left chest but without any change in his condition. Post-mortem examination revealed a ruptured abdominal aortic aneurysm as the cause of death. Multiple left rib fractures and a left lung laceration secondary to the use of the ACD device were also noted, although the pathologist felt that the tension pneumothorax had not contributed to the patient's death. It is recommended that a simple or tension pneumothorax should be considered when there is unilateral absence of breath sounds in addition to endobronchial intubation if an ACD device is being used.

  7. Improving Abnormality Detection on Chest Radiography Using Game-Like Reinforcement Mechanics.

    PubMed

    Chen, Po-Hao; Roth, Howard; Galperin-Aizenberg, Maya; Ruutiainen, Alexander T; Gefter, Warren; Cook, Tessa S

    2017-06-21

    Despite their increasing prevalence, online textbooks, question banks, and digital references focus primarily on explicit knowledge. Implicit skills such as abnormality detection require repeated practice on clinical service and have few digital substitutes. Using mechanics traditionally deployed in video games such as clearly defined goals, rapid-fire levels, and narrow time constraints may be an effective way to teach implicit skills. We created a freely available, online module to evaluate the ability of individuals to differentiate between normal and abnormal chest radiographs by implementing mechanics, including instantaneous feedback, rapid-fire cases, and 15-second timers. Volunteer subjects completed the modules and were separated based on formal experience with chest radiography. Performance between training and testing sets were measured for each group, and a survey was administered after each session. The module contained 74 cases and took approximately 20 minutes to complete. Thirty-two cases were normal radiographs and 56 cases were abnormal. Of the 60 volunteers recruited, 25 were "never trained" and 35 were "previously trained." "Never trained" users scored 21.9 out of 37 during training and 24.0 out of 37 during testing (59.1% vs 64.9%, P value <.001). "Previously trained" users scored 28.0 out of 37 during training and 28.3 out of 37 during testing phases (75.6% vs 76.4%, P value = .56). Survey results showed that 87% of all subjects agreed the module is an efficient way of learning, and 83% agreed the rapid-fire module is valuable for medical students. A gamified online module may improve the abnormality detection rates of novice interpreters of chest radiography, although experienced interpreters are less likely to derive similar benefits. Users reviewed the educational module favorably. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  8. Lung and chest wall mechanics during exercise: effects of expiratory flow limitation.

    PubMed

    Aliverti, Andrea

    2008-11-30

    This short review summarizes how lung and chest wall mechanics can be modelled and which are the mechanical constraints imposed on the ventilatory system and its components during exercise. In healthy humans the structural and functional characteristics of the ventilator pump are able to meet the increased demands of ventilation during exercise and it is rare that arterial blood gas is significantly altered up to maximal exercise. In contrast, exercise is frequently limited by the ventilator system in disease, especially when altered mechanical properties of the airway and lung make expiratory flow limitation (EFL) a common feature. EFL is a phenomenon that can be understood in terms of the viscous effects of gas flowing from the alveoli to the airway opening along a collapsible airway which leads during exercise to dynamic hyperflation and several abnormalities of the ventilatory pump. These, in turn, determine a series of secondary manifestations, namely dyspnoea, exercise limitation and hypercapnia that can cause serious morbidity.

  9. Effects of expiratory rib-cage compression on oxygenation, ventilation, and airway-secretion removal in patients receiving mechanical ventilation.

    PubMed

    Unoki, Takeshi; Kawasaki, Yuri; Mizutani, Taro; Fujino, Yoko; Yanagisawa, Yaeko; Ishimatsu, Shinichi; Tamura, Fumiko; Toyooka, Hidenori

    2005-11-01

    Expiratory rib-cage compression, a chest physiotherapy technique, is well known as the "squeezing" technique in Japan. To determine the effects of rib-cage compression on airway-secretion removal, oxygenation, and ventilation in patients receiving mechanical ventilation. An intensive care unit of an emergency and critical care center at a tertiary-care teaching hospital in Tokyo, Japan. Thirty-one intubated, mechanically ventilated patients in an intensive care unit were studied in a randomized, crossover trial. The patients received endotracheal suctioning with or without rib-cage compression, with a minimum 3-hour interval between the 2 interventions. Rib-cage compression was performed for 5 min before endotracheal suctioning. Arterial blood gas and respiratory mechanics were measured 5 min before endotracheal suctioning (baseline) and 25 min after suctioning. The 2 measurement periods were carried out on the same day. There were no significant differences in the ratio of arterial partial pressure of oxygen to fraction of inspired oxygen, P(aCO2), or dynamic compliance of the respiratory system between the 2 periods (before and after endotracheal suctioning). Moreover, there were no significant differences in airway-secretion removal between the 2 periods. This study suggests that rib-cage compression prior to endotracheal suctioning does not improve airway-secretion removal, oxygenation, or ventilation after endotracheal suctioning in this unselected population of mechanically ventilated patients.

  10. Influence of compression parameters on mechanical behavior of mozzarella cheese.

    PubMed

    Fogaça, Davi Novaes Ladeia; da Silva, William Soares; Rodrigues, Luciano Brito

    2017-10-01

    Studies on the interaction between direction and degree of compression in the Texture Profile Analysis (TPA) of cheeses are limited. For this reason the present study aimed to evaluate the mechanical properties of Mozzarella cheese by TPA at different compression degrees (65, 75, and 85%) and directions (axes X, Y, and Z). Data obtained were compared in order to identify possible interaction between both factors. Compression direction did not affect any mechanical variable, or rather, the cheese had an isotropic behavior for TPA. Compression degree had a significant influence (p < 0.05) on TPA responses, excepting for chewiness TPA (N), which remained constant. Data from texture profile were adjusted to models to explain the mechanical behavior according to the compression degree used in the test. The isotropic behavior observed may be result of differences in production method of Mozzarella cheese especially on stretching of cheese mass. Texture Profile Analysis (TPA) is a technique largely used to assess the mechanical properties of food, particularly cheese. The precise choice of the instrumental test configuration is essential for achieving results that represent the material analyzed. The method of manufacturing is another factor that may directly influence the mechanical properties of food. This can be seen, for instance, in stretched curd cheese, such as Mozzarella. Knowledge on such mechanical properties is highly relevant for food industries due to the mechanical resistance in piling, pressing, manufacture of packages, and food transport, or to melting features presented by the food at high temperatures in preparation of several foods, such as pizzas, snacks, sandwiches, and appetizers. © 2016 Wiley Periodicals, Inc.

  11. Compressive fracture morphology and mechanism of metallic glass

    NASA Astrophysics Data System (ADS)

    Qu, R. T.; Zhang, Z. F.

    2013-11-01

    We quantitatively investigated the fracture morphologies of Zr52.5Cu17.9Ni14.6Al10Ti5 and Pd78Cu6Si16 metallic glasses (MGs) under compression. The characteristic features of the compressive fracture morphology were captured, and the shear vein patterns were found to be not a one-to-one correspondence between two opposing fracture surfaces in an identical sample. This finding experimentally confirms that the compressive failure behaves in a fracture mode of pure shear (mode II). Quantitative measurements show that a ˜1 μm thickness layer with materials not only inside but also adjacent to the major shear band contributes to the formation of shear vein patterns. The critical shear strain to break a shear band was found to be more than 105% and higher in more ductile MGs under compression than tension. Estimation on the temperature rise at the fracture moment indicates that only ˜5% of the total elastic energy stored in the sample converts into the heat required for melting the layer to form the vein patterns. The mode II fracture toughness was also estimated based on the quantitative measurements of shear vein pattern and found larger than the mode I fracture toughness. Finally, the deformation and fracture mechanisms of MGs under tension and compression were compared and discussed. These results may improve the understanding on the fracture behaviors and mechanisms of MGs and may provide instructions on future design for ductile MGs with high resistance for fracture.

  12. Failure Mechanisms of Brittle Rocks under Uniaxial Compression

    NASA Astrophysics Data System (ADS)

    Liu, Taoying; Cao, Ping

    2017-09-01

    The behaviour of a rock mass is determined not only by the properties of the rock matrix, but mostly by the presence and properties of discontinuities or fractures within the mass. The compression test on rock-like specimens with two prefabricated transfixion fissures, made by pulling out the embedded metal inserts in the pre-cured period was carried out on the servo control uniaxial loading tester. The influence of the geometry of pre-existing cracks on the cracking processes was analysed with reference to the experimental observation of crack initiation and propagation from pre-existing flaws. Based on the rock fracture mechanics and the stress-strain curves, the evolution failure mechanism of the fissure body was also analyzed on the basis of exploring the law of the compression-shear crack initiation, wing crack growth and rock bridge connection. Meanwhile, damage fracture mechanical models of a compression-shear rock mass are established when the rock bridge axial transfixion failure, tension-shear combined failure, or wing crack shear connection failure occurs on the specimen under axial compression. This research was of significance in studying the failure mechanism of fractured rock mass.

  13. Poroelastic Mechanical Effects of Hemicelluloses on Cellulosic Hydrogels under Compression

    PubMed Central

    Lopez-Sanchez, Patricia; Cersosimo, Julie; Wang, Dongjie; Flanagan, Bernadine; Stokes, Jason R.; Gidley, Michael J.

    2015-01-01

    Hemicelluloses exhibit a range of interactions with cellulose, the mechanical consequences of which in plant cell walls are incompletely understood. We report the mechanical properties of cell wall analogues based on cellulose hydrogels to elucidate the contribution of xyloglucan or arabinoxylan as examples of two hemicelluloses displaying different interactions with cellulose. We subjected the hydrogels to mechanical pressures to emulate the compressive stresses experienced by cell walls in planta. Our results revealed that the presence of either hemicellulose increased the resistance to compression at fast strain rates. However, at slow strain rates, only xyloglucan increased composite strength. This behaviour could be explained considering the microstructure and the flow of water through the composites confirming their poroelastic nature. In contrast, small deformation oscillatory rheology showed that only xyloglucan decreased the elastic moduli. These results provide evidence for contrasting roles of different hemicelluloses in plant cell wall mechanics and man-made cellulose-based composite materials. PMID:25794048

  14. Mechanisms of compressive failure in woven composites and stitched laminates

    NASA Technical Reports Server (NTRS)

    Cox, B. N.; Dadkhah, M. S.; Inman, R. V.; Morris, W. L.; Schroeder, S.

    1992-01-01

    Stitched laminates and angle interlock woven composites have been studied in uniaxial, in-plane, monotonic compression. Failure mechanisms have been found to depend strongly on both the reinforcement architecture and the degree of constraint imposed by the loading grips. Stitched laminates show higher compressive strength, but are brittle, possessing no load bearing capacity beyond the strain for peak load. Post-mortem inspection shows a localized shear band of buckled and broken fibers, which is evidently the product of an unstably propagating kink band. Similar shear bands are found in the woven composites if the constraint of lateral displacements is weak; but, under strong constraint, damage is not localized but distributed throughout the gauge section. While the woven composites tested are weaker than the stitched laminates, they continue to bear significant loads to compressive strains of approx. 15 percent, even when most damage is confined to a shear band.

  15. [Chest physical therapy of the distal lung. Mechanical basis of a new paradigm].

    PubMed

    Postiaux, G

    2014-06-01

    Recent medical literature has shown that there has been renewed interest focused on the small airways deep in the lung tissue. Although there is involvement of the distal airways at an early stage in mucus secreting lung diseases, no specific chest physical therapy (CPT) manoeuver has been proposed for small airways clearance. A four-tier classification of CPT has been established with identification of its benefits at each level of a monoalveolar respiratory tract model. The usual expiratory techniques directed towards the upper and middle respiratory tract are not applicable to the small airways and new paradigm is proposed appropriate to their specific mechanical characteristics. This comprises a slow resistive inspiratory manoeuver in the lateral position. Clinical auscultation of the lung is the cornerstone of the validation and follow-up of the technique. Copyright © 2014 SPLF. Published by Elsevier Masson SAS. All rights reserved.

  16. Computerized detection of vertebral compression fractures on lateral chest radiographs: Preliminary results with a tool for early detection of osteoporosis

    SciTech Connect

    Kasai, Satoshi; Li Feng; Shiraishi, Junji; Li Qiang; Doi, Kunio

    2006-12-15

    Vertebral fracture (or vertebral deformity) is a very common outcome of osteoporosis, which is one of the major public health concerns in the world. Early detection of vertebral fractures is important because timely pharmacologic intervention can reduce the risk of subsequent additional fractures. Chest radiographs are used routinely for detection of lung and heart diseases, and vertebral fractures can be visible on lateral chest radiographs. However, investigators noted that about 50% of vertebral fractures visible on lateral chest radiographs were underdiagnosed or under-reported, even when the fractures were severe. Therefore, our goal was to develop a computerized method for detection of vertebral fractures on lateral chest radiographs in order to assist radiologists' image interpretation and thus allow the early diagnosis of osteoporosis. The cases used in this study were 20 patients with severe vertebral fractures and 118 patients without fractures, as confirmed by the consensus of two radiologists. Radiologists identified the locations of fractured vertebrae, and they provided morphometric data on the vertebral shape for evaluation of the accuracy of detecting vertebral end plates by computer. In our computerized method, a curved search area, which included a number of vertebral end plates, was first extracted automatically, and was straightened so that vertebral end plates became oriented horizontally. Edge candidates were enhanced by use of a horizontal line-enhancement filter in the straightened image, and a multiple thresholding technique, followed by feature analysis, was used for identification of the vertebral end plates. The height of each vertebra was determined from locations of identified vertebral end plates, and fractured vertebrae were detected by comparison of the measured vertebral height with the expected height. The sensitivity of our computerized method for detection of fracture cases was 95% (19/20), with 1.03 (139/135) false

  17. Computerized detection of vertebral compression fractures on lateral chest radiographs: preliminary results with a tool for early detection of osteoporosis.

    PubMed

    Kasai, Satoshi; Li, Feng; Shiraishi, Junji; Li, Qiang; Doi, Kunio

    2006-12-01

    Vertebral fracture (or vertebral deformity) is a very common outcome of osteoporosis, which is one of the major public health concerns in the world. Early detection of vertebral fractures is important because timely pharmacologic intervention can reduce the risk of subsequent additional fractures. Chest radiographs are used routinely for detection of lung and heart diseases, and vertebral fractures can be visible on lateral chest radiographs. However, investigators noted that about 50% of vertebral fractures visible on lateral chest radiographs were underdiagnosed or under-reported, even when the fractures were severe. Therefore, our goal was to develop a computerized method for detection of vertebral fractures on lateral chest radiographs in order to assist radiologists' image interpretation and thus allow the early diagnosis of osteoporosis. The cases used in this study were 20 patients with severe vertebral fractures and 118 patients without fractures, as confirmed by the consensus of two radiologists. Radiologists identified the locations of fractured vertebrae, and they provided morphometric data on the vertebral shape for evaluation of the accuracy of detecting vertebral end plates by computer. In our computerized method, a curved search area, which included a number of vertebral end plates, was first extracted automatically, and was straightened so that vertebral end plates became oriented horizontally. Edge candidates were enhanced by use of a horizontal line-enhancement filter in the straightened image, and a multiple thresholding technique, followed by feature analysis, was used for identification of the vertebral end plates. The height of each vertebra was determined from locations of identified vertebral end plates, and fractured vertebrae were detected by comparison of the measured vertebral height with the expected height. The sensitivity of our computerized method for detection of fracture cases was 95% (19/20), with 1.03 (139/135) false

  18. Mechanical compression for contrasting OCT images of biotissues

    NASA Astrophysics Data System (ADS)

    Kirillin, Mikhail Y.; Argba, Pavel D.; Kamensky, Vladislav A.

    2011-06-01

    Contrasting of biotissue layers in OCT images after application of mechanical compression is discussed. The study is performed on ex vivo samples of human rectum, and in vivo on skin of human volunteers. We show that mechanical compression provides contrasting of biotissue layer boundaries due to different mechanical properties of layers. We show that alteration of pressure from 0 up to 0.45 N/mm2 causes contrast increase from 1 to 10 dB in OCT imaging of human rectum ex vivo. Results of ex vivo studies are in good agreement with Monte Carlo simulations. Application of pressure of 0.45 N/mm2 causes increase in contrast of epidermis-dermis junction in OCT-images of human skin in vivo for about 10 dB.

  19. Physiological effects of a single chest physiotherapy session in mechanically ventilated and extubated preterm neonates.

    PubMed

    Mehta, Y; Shetye, J; Nanavati, R; Mehta, A

    2016-01-01

    To assess the changes on various physiological cardio-respiratory parameters with a single chest physiotherapy session in mechanically ventilated and extubated preterm neonates with respiratory distress syndrome. This is a prospective observational study in a neonatal intensive care unit setting. Sixty preterm neonates with respiratory distress syndrome, thirty mechanically ventilated and thirty extubated preterm neonates requiring chest physiotherapy were enrolled in the study. Parameters like heart rate (HR), respiratory rate (RR), Silverman Anderson score (SA score in extubated), oxygen saturation (SpO2) and auscultation findings were noted just before, immediately after chest physiotherapy but before suctioning, immediately after suctioning and after 5 minutes of the session. The mean age of neonates was 9.55±5.86 days and mean birth weight was 1550±511.5 g. As there was no significant difference in the change in parameters on intergroup comparison, further analysis was done considering two groups together (n = 60) except for SA score. As SA score was measured only in extubated neonates. HR did not change significantly during chest physiotherapy compared to the baseline but significantly decreased after 15 minutes (p = 0.01). RR and SA score significantly increased after suctioning (p = 0.014) but reduced after 15 minutes (p = <0.0001). SpO2 significantly reduced post-suctioning compared to the baseline and increased after positioning and 15 minutes of chest physiotherapy (p = <0.0001). Clinically, there was a reduction in HR, RR and SA score with an improvement in SpO2. This signifies that chest physiotherapy may help facilitate the overall well-being of a fragile preterm neonate. Lung auscultation finding suggests that after suctioning, there was a significant reduction in crepitation (p = 0.0000) but significant increase in crepitation after 15 minutes (p = <0.01), suggesting the importance of around-the-clock chest

  20. Compressive and tensile mechanical properties of the porcine nasal septum.

    PubMed

    Al Dayeh, Ayman A; Herring, Susan W

    2014-01-03

    The expanding nasal septal cartilage is believed to create a force that powers midfacial growth. In addition, the nasal septum is postulated to act as a mechanical strut that prevents the structural collapse of the face under masticatory loads. Both roles imply that the septum is subject to complex biomechanical loads during growth and mastication. The purpose of this study was to measure the mechanical properties of the nasal septum to determine (1) whether the cartilage is mechanically capable of playing an active role in midfacial growth and in maintaining facial structural integrity and (2) if regional variation in mechanical properties is present that could support any of the postulated loading regimens. Porcine septal samples were loaded along the horizontal or vertical axes in compression and tension, using different loading rates that approximate the in vivo situation. Samples were loaded in random order to predefined strain points (2-10%) and strain was held for 30 or 120 seconds while relaxation stress was measured. Subsequently, samples were loaded until failure. Stiffness, relaxation stress and ultimate stress and strain were recorded. Results showed that the septum was stiffer, stronger and displayed a greater drop in relaxation stress in compression compared to tension. Under compression, the septum displayed non-linear behavior with greater stiffness and stress relaxation under faster loading rates and higher strain levels. Under tension, stiffness was not affected by strain level. Although regional variation was present, it did not strongly support any of the suggested loading patterns. Overall, results suggest that the septum might be mechanically capable of playing an active role in midfacial growth as evidenced by increased compressive residual stress with decreased loading rates. However, the low stiffness of the septum compared to surrounding bone does not support a strut role. The relatively low stiffness combined with high stress relaxation

  1. Compressive and tensile mechanical properties of the porcine nasal septum

    PubMed Central

    Al Dayeh, Ayman A.; Herring, Susan W.

    2013-01-01

    The expanding nasal septal cartilage is believed to create a force that powers midfacial growth. In addition, the nasal septum is postulated to act as a mechanical strut that prevents the structural collapse of the face under masticatory loads. Both roles imply that the septum is subject to complex biomechanical loads during growth and mastication. The purpose of this study was to measure the mechanical properties of the nasal septum to determine (1) whether the cartilage is mechanically capable of playing an active role in midfacial growth and in maintaining facial structural integrity and (2) if regional variation in mechanical properties is present that could support any of the postulated loading regimens. Porcine septal samples were loaded along the horizontal or vertical axes in compression and tension, using different loading rates that approximate the in vivo situation. Samples were loaded in random order to predefined strain points (2–10%) and strain was held for 30 or 120 seconds while relaxation stress was measured. Subsequently, samples were loaded until failure. Stiffness, relaxation stress and ultimate stress and strain were recorded. Results showed that the septum was stiffer, stronger and displayed a greater drop in relaxation stress in compression compared to tension. Under compression, the septum displayed non-linear behavior with greater stiffness and stress relaxation under faster loading rates and higher strain levels. Under tension, stiffness was not affected by strain level. Although regional variation was present, it did not strongly support any of the suggested loading patterns. Overall, results suggest that the septum might be mechanically capable of playing an active role in midfacial growth as evidenced by increased compressive residual stress with decreased loading rates. However, the low stiffness of the septum compared to surrounding bone does not support a strut role. The relatively low stiffness combined with high stress relaxation

  2. Tuning and synthesis of semiconductor nanostructures by mechanical compression

    DOEpatents

    Fan, Hongyou; Li, Binsong

    2015-11-17

    A mechanical compression method can be used to tune semiconductor nanoparticle lattice structure and synthesize new semiconductor nanostructures including nanorods, nanowires, nanosheets, and other three-dimensional interconnected structures. II-VI or IV-VI compound semiconductor nanoparticle assemblies can be used as starting materials, including CdSe, CdTe, ZnSe, ZnS, PbSe, and PbS.

  3. Role of compressive sensing technique in dose reduction for chest computed tomography: a prospective blinded clinical study.

    PubMed

    Khawaja, Ranish Deedar Ali; Singh, Sarabjeet; Lira, Diego; Bippus, Rolf; Do, Synho; Padole, Atul; Pourjabbar, Sarvenaz; Koehler, Thomas; Shepard, Jo-Anne; Kalra, Mannudeep K

    2014-01-01

    The purpose of this study was to assess pulmonary lesion detection, diagnostic confidence, and noise reduction in sparse-sampled (SpS) computed tomographic (CT) data of submillisievert (SubmSv) chest CT reconstructed with iterative reconstruction technique (IRT). This Human Insurance Portability and Accountability-compliant, institutional review board-approved prospective study was performed using SpS-SubmSv IRT chest CT in 10 non-obese patients (body-mass index, 21-35 kg/m; age range, 26-90 years). Written informed consent was obtained. The patients were scanned at standard-dose CT (mean [SD] volumetric CT dose index, 6 [0.9] mGy; mean [SD] dose-length product, 208 ± 44 mGy·cm; and mean [SD] effective dose, 3 [0.6] mSv) and at SubmSv dose (1.8 [0.2] mGy, 67 [2] mGy·cm, 0.9 [0.03] mSv, respectively) on a Philips 128-slice CT scanner with double z-sampling. Sparse angular sampling data were reconstructed using 25% of the angular projections from the SubmSv sinogram to reduce the number of views and radiation dose by approximately 4-fold. Hence, the patients were scanned and then, simulation-based sparse sampling was performed with a resultant dose hypothetical SpS scan estimated mathematically (0.2 mSv). From each patient data, 3 digital imaging and communications in medicine series were generated: SpS-SubmSv with IRT, fully sampled SubmSv filtered back projection (FBP), and fully sampled standard-dose FBP (SD-FBP). Two radiologists independently assessed these image series for detection of lung lesions, visibility of small structures, and diagnostic acceptability. Objective noise was measured in the thoracic aorta, and noise spectral density was obtained for SpS-SubmSv IRT, SubmSv-FBP, and SD-FBP. The SpS-SubmSv IRT resulted in 75% (0.2/0.9 mSv) and 92% (0.2/2.9 mSv) dose reduction, when compared with the fully sampled SubmSv-FBP and SD-FBP, respectively. Images of SpS-SubmSv displayed all 46 lesions (most <1 cm, 30 lung nodules, 7 ground glass opacities, 9

  4. One-dimensional discrete LQR control of compression of the human chest impulsively loaded by fast moving point mass

    NASA Astrophysics Data System (ADS)

    Olejnik, Paweł; Awrejcewicz, Jan

    2011-05-01

    This paper uncovers some interesting extension of an optimal discrete control methodology partially included in Proceedings and presented at the international conference on "Dynamical Systems Theory and Applications". There has been applied a scheme for realisation of active control strategy with numerically estimated linear optimal quadratic index of performance in reduction of impact-induced deformation of human chest loaded by a point mass at the central point of upper-torso body. We focused on application of one active element attached between torso's upper back (looking from posterior direction) and a fixed support. As the practical result we provide values of quality and reaction matrices, some useful deformation and energy dissipation time-characteristics and the resulting shape of control force time-characteristics that would be the demanding one for a hypothetical real implementation.

  5. Evaluation of the compressive mechanical properties of endoluminal metal stents.

    PubMed

    Schrader, S C; Beyar, R

    1998-06-01

    The mechanical properties of metal stents are important parameters in the consideration of stent design, matched to resist arterial recoil and vascular spasm. The purpose of this study was to develop a system for a standardized quantitative evaluation of the mechanical characteristics of various coronary stents. Several types of stents were compressed by external hydrostatic pressure. The stent diameter was assessed by placing a pair of small ultrasonic sono-crystals on the stent. From pressure-strain diagrams the ultimate strength and radial stiffness for each stent were determined. For all stents, except the MICRO-II and the Wiktor stent, the diameter decreased homogeneously until an ultimate compressive strength was exceeded, causing an abrupt collapse. Expanded to 3 mm, the mechanical behavior of the beStent, the Crown and the Palmaz-Schatz stent (PS153-series) were comparable. The spiral articulated Palmaz-Schatz stent showed twice the strength (1.26 atm) of the PS-153 (0.65 atm). The NIR stent yielded a maximum strength of 1.05 atm. The MICRO-II and the Wiktor stent did not collapse abruptly but rather showed a continuous decline of diameter with increasing external pressure. The Cardiocoil stent behaved in a fully elastic manner and showed the largest radial stiffness. Difference in mechanical properties between stents were documented using a new device specifically developed for that purpose. These mechanical stent parameters may have important clinical implications.

  6. What is the optimal chest compression depth during out-of-hospital cardiac arrest resuscitation of adult patients?

    PubMed

    Stiell, Ian G; Brown, Siobhan P; Nichol, Graham; Cheskes, Sheldon; Vaillancourt, Christian; Callaway, Clifton W; Morrison, Laurie J; Christenson, James; Aufderheide, Tom P; Davis, Daniel P; Free, Cliff; Hostler, Dave; Stouffer, John A; Idris, Ahamed H

    2014-11-25

    The 2010 American Heart Association guidelines suggested an increase in cardiopulmonary resuscitation compression depth with a target >50 mm and no upper limit. This target is based on limited evidence, and we sought to determine the optimal compression depth range. We studied emergency medical services-treated out-of-hospital cardiac arrest patients from the Resuscitation Outcomes Consortium Prehospital Resuscitation Impedance Valve and Early Versus Delayed Analysis clinical trial and the Epistry-Cardiac Arrest database. We calculated adjusted odds ratios for survival to hospital discharge, 1-day survival, and any return of circulation. We included 9136 adult patients from 9 US and Canadian cities with a mean age of 67.5 years, mean compression depth of 41.9 mm, and a return of circulation of 31.3%, 1-day survival of 22.8%, and survival to hospital discharge of 7.3%. For survival to discharge, the adjusted odds ratios were 1.04 (95% CI, 1.00-1.08) for each 5-mm increment in compression depth, 1.45 (95% CI, 1.20-1.76) for cases within 2005 depth range (>38 mm), and 1.05 (95% CI, 1.03-1.08) for percentage of minutes in depth range (10% change). Covariate-adjusted spline curves revealed that the maximum survival is at a depth of 45.6 mm (15-mm interval with highest survival between 40.3 and 55.3 mm) with no differences between men and women. This large study of out-of-hospital cardiac arrest patients demonstrated that increased cardiopulmonary resuscitation compression depth is strongly associated with better survival. Our adjusted analyses, however, found that maximum survival was in the depth interval of 40.3 to 55.3 mm (peak, 45.6 mm), suggesting that the 2010 American Heart Association cardiopulmonary resuscitation guideline target may be too high. http://www.clinicaltrials.gov. Unique identifier: NCT00394706. © 2014 American Heart Association, Inc.

  7. Horizontal compression and a mechanical interpretation of Wyoming foreland deformation

    SciTech Connect

    Scheevel, J.R.

    1983-08-01

    If the basement fault-controlled style of deformation in the Wyoming foreland is dominated by elastic response of the upper lithosphere, and the deformation in the foreland is genetically linked to the horizontal compression characteristic of the thin-skinned thrust belt to the west, then concepts of continuum mechanics can be combined with results of experimental rock mechanics to suggest the following. (1) Basement faults initiate at the basement surface, propagate downward at an approximate 35/sup 0/ dip, and die at a depth dependent upon the magnitude of elastic shortening. Displacement on these faults necessarily decreases with depth. The faults are not expected to be appreciably curved in cross section. (2) Foreland structures develop early as fault-cored folds of small amplitude (< 1,500 m, 4,900 ft), with selected ones developing to large amplitudes (up to 13,000 m, 43,000 ft). Regions where the entire lithosphere has not failed (early stage) show only small-scale structures (e.g., Colorado Plateau), whereas regions where the lithosphere has experienced through-going failure will show small intra-basinal structures (early) isolated by more widely spaced large basin-margin structures (late). This biomodal size distribution of structures is present in the Wyoming foreland. In this study, horizontal compression as a sole causal mechanism can be combined with accepted mechanical concepts to produce a plausible model which adequately explains the regional features of Wyoming foreland deformation.

  8. An audiovisual feedback device for compression depth, rate and complete chest recoil can improve the CPR performance of lay persons during self-training on a manikin.

    PubMed

    Krasteva, Vessela; Jekova, Irena; Didon, Jean-Philippe

    2011-06-01

    This study aims to contribute to the scarce data available about the abilities of untrained lay persons to perform hands-only cardio-pulmonary resuscitation (CPR) on a manikin and the improvement of their skills during training with an autonomous CPR feedback device. The study focuses on the following questions: (i) Is there a need for such a CPR training device? (ii) How adequate are the embedded visual feedback and audio guidance for training of lay persons who learn and correct themselves in real time without instructor guidance? (iii) What is the achieved effect of only 3 min of training? This is a prospective study in which 63 lay persons (volunteers) received a debriefing to basic life support and then performed two consecutive 3 min trials of hands-only CPR on a manikin. The pre-training skills of the lay persons were tested in trial 1. The training process with audio guidance and visual feedback from a cardio compression control device (CC-Device) was recorded in trial 2. After initial debriefing for correct chest compressions (CC) with rate 85-115 min(-1), depth 3.8-5.4 cm and complete recoil, in trial 1 the lay persons were able to perform CC without feedback at mean rate 95.9 ± 18.9 min(-1), mean depth 4.13 ± 1.5 cm, with low proportions of 'correct depth', 'correct rate' and 'correct recoil' at 33%, 43%, 87%, resulting in the scarce proportion of 14% for compressions, which simultaneously fulfill the three quality criteria ('correct all'). In trial 2, the training process by the CC-Device was established by the significant improvement of the CC skills until the 60th second of training, when 'correct depth', 'correct rate' and 'correct recoil' attained the plateau of the highest quality at 82%, 90%, 96%, respectively, resulting in 73% 'correct all' compressions within 3 min of training. The training was associated with reduced variance of the mean rate 102.4 ± 4.7 min(-1) and mean depth 4.3 ± 0.4 cm, indicating a steady CC performance achieved among

  9. Effects of manual rib-cage compression versus PEEP-ZEEP maneuver on respiratory system compliance and oxygenation in patients receiving mechanical ventilation.

    PubMed

    Santos, Flavio Renato Antunes Dos; Schneider Júnior, Luiz Carlos; Forgiarini Junior, Luiz Alberto; Veronezi, Jefferson

    2009-06-01

    Patients unable to perform breathing functions may be submitted to invasive mechanical ventilation. Chest physiotherapy acts directly on the treatment of these patients for the purpose of improving their lung function. The objective of this study was to evaluate the effects of manual rib-cage compression versus the positive end expiratory pressure-zero end expiratory pressure (PEEP-ZEEP) maneuver, on compliance of the respiratory system and oxygenation in patients under invasive mechanical ventilation. A double centric, prospective, randomized and crossover study, with patients under invasive mechanical ventilation, in controlled mode for more than 48 hours was carried out. The protocols of chest physiothe-rapy were randomly applied at an interval of 24 hours. Data of respiratory system compliance and oxygenation were collected before application of the protocols and 30 minutes after. Twelve patients completed the study. Intragroup analysis, for both techniques showed a statistically significant difference in tidal volume (p=0.002), static compliance (p=0.002) and dynamic compliance (p=0.002). In relation to oxygenation, in the group of manual rib-cage compression, peripheral oxygen saturation increased with a significant difference (p=0.011). Manual rib-cage compression and PEEP-ZEEP maneuver have positive clinical effects. In relation to oxygenation we found a favorable behavior of peripheral oxygen saturation in the group of manual rib-cage compression.

  10. The nature and extent of organisms in vessel sea-chests: A protected mechanism for marine bioinvasions.

    PubMed

    Coutts, Ashley D M; Dodgshun, Tim J

    2007-07-01

    A total of 150 different organisms, including one plant species and 12 animal phyla were identified from sea-chests of 42 vessels visiting or operating in New Zealand between May 2000 and November 2004. Forty-nine percent of organisms were sessile, 42% mobile adults and the remaining 9% sedentary. Decapods were the most represented group with 19 species present among 79% of vessels. Forty percent of organisms were indigenous to New Zealand, 15% introduced, 10% non-indigenous, and 35% of unknown origin. Sea-chests have the potential to (1) transfer non-indigenous organisms between countries across oceanic boundaries; and (2) disperse both indigenous and introduced organisms domestically. The occurrence of adult mobile organisms is particularly significant and indicates that sea-chests may be of greater importance than ballast water or hull fouling for dispersing certain marine species. These findings emphasise the need to assess and manage biosecurity risks for entire vessels rather than different mechanisms (i.e., ballast water, hull fouling, sea-chests, etc.) in isolation.

  11. Up-down hand position switch may delay the fatigue of non-dominant hand position rescuers and improve chest compression quality during cardiopulmonary resuscitation: a randomized crossover manikin study.

    PubMed

    Zhou, Xian-Long; Li, Lei; Jiang, Cheng; Xu, Bing; Wang, Huang-Lei; Xiong, Dan; Sheng, Li-Pin; Yang, Qi-Sheng; Jiang, Shan; Xu, Peng; Chen, Zhi-Qiao; Zhao, Yan

    2015-01-01

    Previous studies have shown improved external chest compression (ECC) quality and delayed rescuer fatigue when the dominant hand (DH) was in contact with the sternum. However, many rescuers prefer placing the non-dominant hand (NH) in contact with the sternum during ECC. We aimed to investigate the effects of up-down hand position switch on the quality of ECC and the fatigue of rescuers during cardiopulmonary resuscitation (CPR). After completion of a review of the standard adult basic life support (BLS) course, every candidate performed 10 cycles of single adult CPR twice on an adult manikin with either a constant hand position (CH) or a switched hand position (SH) in random order at 7-day intervals. The rescuers' general characteristics, hand positions, physiological signs, fatigue appearance and ECC qualities were recorded. Our results showed no significant differences in chest compression quality for the DH position rescuers between the CH and SH sessions (p>0.05, resp.). And also no significant differences were found for Borg score (p = 0.437) or cycle number (p = 0.127) of fatigue appearance after chest compressions between the two sessions. However, for NH position rescuers, the appearance of fatigue was delayed (p = 0.046), with a lower Borg score in the SH session (12.67 ± 2.03) compared to the CH session (13.33 ± 1.95) (p = 0.011). Moreover, the compression depth was significantly greater in the SH session (39.3 ± 7.2 mm) compared to the CH session (36.3 ± 8.1 mm) (p = 0.015). Our data suggest that the up-down hand position switch during CPR may delay the fatigue of non-dominant hand position rescuers and improve the quality of chest compressions.

  12. Up-Down Hand Position Switch May Delay the Fatigue of Non-Dominant Hand Position Rescuers and Improve Chest Compression Quality during Cardiopulmonary Resuscitation: A Randomized Crossover Manikin Study

    PubMed Central

    Xu, Bing; Wang, Huang-Lei; Xiong, Dan; Sheng, Li-Pin; Yang, Qi-Sheng; Jiang, Shan; Xu, Peng; Chen, Zhi-Qiao; Zhao, Yan

    2015-01-01

    Previous studies have shown improved external chest compression (ECC) quality and delayed rescuer fatigue when the dominant hand (DH) was in contact with the sternum. However, many rescuers prefer placing the non-dominant hand (NH) in contact with the sternum during ECC. We aimed to investigate the effects of up-down hand position switch on the quality of ECC and the fatigue of rescuers during cardiopulmonary resuscitation (CPR). After completion of a review of the standard adult basic life support (BLS) course, every candidate performed 10 cycles of single adult CPR twice on an adult manikin with either a constant hand position (CH) or a switched hand position (SH) in random order at 7-day intervals. The rescuers’ general characteristics, hand positions, physiological signs, fatigue appearance and ECC qualities were recorded. Our results showed no significant differences in chest compression quality for the DH position rescuers between the CH and SH sessions (p>0.05, resp.). And also no significant differences were found for Borg score (p = 0.437) or cycle number (p = 0.127) of fatigue appearance after chest compressions between the two sessions. However, for NH position rescuers, the appearance of fatigue was delayed (p = 0.046), with a lower Borg score in the SH session (12.67 ± 2.03) compared to the CH session (13.33 ± 1.95) (p = 0.011). Moreover, the compression depth was significantly greater in the SH session (39.3 ± 7.2 mm) compared to the CH session (36.3 ± 8.1 mm) (p = 0.015). Our data suggest that the up-down hand position switch during CPR may delay the fatigue of non-dominant hand position rescuers and improve the quality of chest compressions. PMID:26267353

  13. Return of spontaneous Circulation Is Not Affected by Different Chest Compression Rates Superimposed with Sustained Inflations during Cardiopulmonary Resuscitation in Newborn Piglets

    PubMed Central

    Li, Elliott S.; Cheung, Po-Yin; Lee, Tze-Fun; Lu, Min; O'Reilly, Megan

    2016-01-01

    Objective Recently, sustained inflations (SI) during chest compression (CC) have been suggested as an alternative to the current approach during neonatal resuscitation. However, the optimal rate of CC during SI has not yet been established. Our aim was to determine whether different CC rates during SI reduce time to return of spontaneous circulation (ROSC) and improve hemodynamic recovery in newborn piglets with asphyxia-induced bradycardia. Intervention and measurements Term newborn piglets were anesthetized, intubated, instrumented and exposed to 45-min normocapnic hypoxia followed by asphyxia. Resuscitation was initiated when heart rate decreased to 25% of baseline. Piglets were randomized into three groups: CC superimposed by SI at a rate of 90 CC per minute (SI+CC 90, n = 8), CC superimposed by SI at a rate of 120 CC per minute (SI+CC 120, n = 8), or a sham group (n = 6). Cardiac function, carotid blood flow, cerebral oxygenation and respiratory parameters were continuously recorded throughout the experiment. Main results Both treatment groups had similar time of ROSC, survival rates, hemodynamic and respiratory parameters during cardiopulmonary resuscitation. The hemodynamic recovery in the subsequent 4h was similar in both groups and was only slightly lower than sham-operated piglets at the end of experiment. Conclusion Newborn piglets resuscitated by SI+CC 120 did not show a significant advantage in ROSC, survival, and hemodynamic recovery as compared to those piglets resuscitated by SI+CC 90. PMID:27304210

  14. Statistical mechanics analysis of thresholding 1-bit compressed sensing

    NASA Astrophysics Data System (ADS)

    Xu, Yingying; Kabashima, Yoshiyuki

    2016-08-01

    The one-bit compressed sensing framework aims to reconstruct a sparse signal by only using the sign information of its linear measurements. To compensate for the loss of scale information, past studies in the area have proposed recovering the signal by imposing an additional constraint on the l 2-norm of the signal. Recently, an alternative strategy that captures scale information by introducing a threshold parameter to the quantization process was advanced. In this paper, we analyze the typical behavior of thresholding 1-bit compressed sensing utilizing the replica method of statistical mechanics, so as to gain an insight for properly setting the threshold value. Our result shows that fixing the threshold at a constant value yields better performance than varying it randomly when the constant is optimally tuned, statistically. Unfortunately, the optimal threshold value depends on the statistical properties of the target signal, which may not be known in advance. In order to handle this inconvenience, we develop a heuristic that adaptively tunes the threshold parameter based on the frequency of positive (or negative) values in the binary outputs. Numerical experiments show that the heuristic exhibits satisfactory performance while incurring low computational cost.

  15. Interaction of Anti-G Measures and Chest Wall Mechanics in Determining Gas Exchange.

    DTIC Science & Technology

    1983-05-01

    transition between a relatively non-compliant upper rib cage and the more compliant lower chest wall. Lupi -Herrera et al. (1976) exposed dogs to...Patterson, Jr. Elevation gradient of intrathoracic pressure. J. Appl. Physiol. 16: 465-468, 1961. 17. Lupi -Herrera, E., C. Prefaut, A.E. Grassino and N.R

  16. A comparison of manual to mechanical chest percussion for clearance of alveolar material in patients with pulmonary alveolar proteinosis (phospholipidosis).

    PubMed

    Hammon, W E; McCaffree, D R; Cucchiara, A J

    1993-05-01

    To our knowledge, there are no studies that compare the effectiveness of manual chest percussion (MN), mechanical chest percussion (MC), and no percussion (NP) for removing the proteinaceous material found in the alveoli of patients with pulmonary alveolar proteinosis (PAP) while undergoing whole-lung bronchopulmonary lavage (BPL). We analyzed the optical densities (OD) of 27 bottles of effluent from three BPLs of a patient with PAP. One technique was used per bottle. The order of techniques was balanced within each nine-bottle series and among the three BPLs. The mean OD for MN (0.933 +/- 0.494) was significantly superior to MC (0.477 +/- 0.265) (p < 0.0005) and NP (0.318 +/- 0.242) (p < 0.0001). We conclude that MN is superior to MC and NP and increases the therapeutic results of BPL for PAP.

  17. Effects of expiratory rib cage compression and/or prone position on oxygenation and ventilation in mechanically ventilated rabbits with induced atelectasis.

    PubMed

    Unoki, Takeshi; Mizutani, Taro; Toyooka, Hidenori

    2003-08-01

    Expiratory rib cage compression is a chest physiotherapy technique known as "squeezing" technique in Japan. It has been claimed that rib cage compression effectively treats and/or prevents lung collapse, but no studies have been reported on rib cage compression focused on improving ventilation and/or oxygenation in subjects with collapsed lung. Therefore, we studied whether rib cage compression, with and without prone positioning, improves the ratio of P(aO)(2) to fraction of inspired oxygen (P(aO)(2)/F(IO)(2)), P(aCO)(2), or dynamic compliance of the respiratory system. We used anesthetized adult rabbits with induced atelectasis. An endotracheal tube and an 18-gauge catheter were placed into the airway via a tracheostoma, and pressure-controlled mechanical ventilation was used. To create atelectasis, artificial mucus was infused into the airway via the catheter. The rabbits were randomly assigned to one of 4 groups ( = 10 in each group): (1) supine without rib cage compression, (2) supine with rib cage compression, (3) prone without rib cage compression, and (4) prone with rib cage compression. Each rib cage compression session lasted for 5 min and was repeated 5 times every 30 min. After these interventions for 180 min all animals were placed in the supine position for 120 min. The prone-position groups had significantly higher P(aO)(2)/F(IO)(2) than the supine-position groups at 60 min after the beginning of the intervention, and at 60, 90, and 120 min after the end of the intervention (p < 0.05). Rib cage compression did not significantly affect P(aO)(2)/F(IO)(2), P(aO)(2), or dynamic compliance. It is unlikely that rib cage compression re-expands collapsed lung. Prone positioning improved oxygenation in rabbits with induced atelectasis.

  18. Compressive mechanical properties of porous GO materials prepared from freeze-drying method

    NASA Astrophysics Data System (ADS)

    Chen, Hui; Li, Zheng; Liu, Xing; Ren, Hu-Ming; Tang, Xian-Qiong; Zhang, Ping; Ding, Yan-Huai

    2017-02-01

    In this paper porous graphene oxide (GO) foams were prepared from freeze-drying method. Compressive mechanical properties of GO foams with different density were investigated by uniaxial compression experiments and finite element (FE) simulation. GO foam exhibited excellent elasticity, which recovered to its original length even after 300 cycles. The structural evolution during the compression was revealed by FE simulation.

  19. Chest radiology

    SciTech Connect

    Austin, J.H.M.

    1982-01-01

    This review of chest radiology reexamines normal findings on plain chest radiographs, and presents a new plain film view for detecting metastases in the lungs, and describes new findings on acute and chronic inflammatory diseases. Various chest radiologic procedures are examined. (KRM)

  20. Alternatives to percussion and postural drainage. A review of mucus clearance therapies: percussion and postural drainage, autogenic drainage, positive expiratory pressure, flutter valve, intrapulmonary percussive ventilation, and high-frequency chest compression with the ThAIRapy Vest.

    PubMed

    Langenderfer, B

    1998-01-01

    The purpose of this article is to review published studies on the efficacy of old and new mucus clearance techniques and to develop recommendations for different groups of patients. Mucus clearance is a problem in cystic fibrosis, bronchiectasis, and many other pulmonary conditions. Percussion and postural drainage (P & PD) was the traditional method of facilitating mucus clearance, but the many hazards and contraindications along with the onerous nature and resultant poor patient compliance of this procedure have led to the development of alternative therapies. Research studies with cystic fibrosis patients support the efficacy of P & PD in patients who can tolerate it. However, equivalent sputum production can be accomplished with autogenic drainage, positive expiratory pressure, and Flutter valve therapy without the assistance of another caregiver, as long as the patient has the motivation, breath control, and neuromuscular function to perform these modalities. The Intrapulmonary Percussive Ventilation device and high-frequency chest compression with the ThAIRapy vest involve more elaborate and expensive equipment, yet these devices provide mucus clearance assistance to patients who lack the ability to perform the simpler techniques. Both mechanized modalities promote independence and self-care in the patient, and the effectiveness of both has been supported by the limited research published to date. Which alternative to recommend depends on the ability, motivation, preference, needs, and resources of each patient.

  1. The impact of ultra-brief chest compression-only CPR video training on responsiveness, compression rate, and hands-off time interval among bystanders in a shopping mall.

    PubMed

    Panchal, Ashish R; Meziab, Omar; Stolz, Uwe; Anderson, Wes; Bartlett, Mitchell; Spaite, Daniel W; Bobrow, Bentley J; Kern, Karl B

    2014-09-01

    Recent studies have demonstrated higher-quality chest compressions (CCs) following a 60 s ultra-brief video (UBV) on compression-only CPR (CO-CPR). However, the effectiveness of UBVs as a CPR-teaching tool for lay bystanders in public venues remains unknown. Determine whether an UBV is effective in teaching laypersons CO-CPR in a public setting and if viewing leads to superior responsiveness and CPR skills. Adult lay bystanders were enrolled in a public shopping mall and randomized to: (1) Control (CTR): sat idle for 60 s; (2) UBV: watched a 60 s UBV on CO-CPR. Subjects were read a scenario detailing a sudden collapse in the mall and asked to do what they "thought was best" on a mannequin. Performance measures were recorded for 2 min: responsiveness (time to call 911 and first CCs) and CPR quality [CC depth, rate, hands-off interval (time without CC after first CC)]. One hundred subjects were enrolled. Demographics were similar between groups. UBV subjects called 911 more frequently (percent difference: 31%) and initiated CCs sooner in the arrest scenario (median difference (MD): 5 s). UBV cohort had increased CC rate (MD: 19 cpm) and decreased hands-off interval (MD: 27 s). There was no difference in CC depth. Bystanders with UBV training in a shopping mall had significantly improved responsiveness, CC rate, and decreased hands-off interval. Given the short length of training, UBV may have potential as a ubiquitous intervention for public venues to help improve bystander reaction to arrest and CO-CPR performance. Published by Elsevier Ireland Ltd.

  2. Mechanics of particulate composites with glassy polymer binders in compression.

    PubMed

    Jordan, J L; Spowart, J E; Kendall, M J; Woodworth, B; Siviour, C R

    2014-05-13

    Whether used as structural components in design or matrix materials for composites, the mechanical properties of polymers are increasingly important. The compressive response of extruded polymethyl methacrylate (PMMA) rod with aligned polymer chains and Al-Ni-PMMA particulate composites are investigated across a range of strain rates and temperatures. The particulate composites were prepared using an injection-moulding technique resulting in highly anisotropic microstructures. The mechanics of these materials are discussed in the light of theories of deformation for glassy polymers. The experimental data from this study are compared with PMMA results from the literature as well as epoxy-based composites with identical particulates. The PMMA exhibited the expected strain rate and temperature dependence and brittle failure was observed at the highest strain rates and lowest temperatures. The Al-Ni-PMMA composites were found to have similar stress-strain response to the PMMA with reduced strain softening after yield. Increasing volume fraction of particulates in the composite resulted in decreased strength.

  3. Mechanics of particulate composites with glassy polymer binders in compression

    PubMed Central

    Jordan, J. L.; Spowart, J. E.; Kendall, M. J.; Woodworth, B.; Siviour, C. R.

    2014-01-01

    Whether used as structural components in design or matrix materials for composites, the mechanical properties of polymers are increasingly important. The compressive response of extruded polymethyl methacrylate (PMMA) rod with aligned polymer chains and Al–Ni–PMMA particulate composites are investigated across a range of strain rates and temperatures. The particulate composites were prepared using an injection-moulding technique resulting in highly anisotropic microstructures. The mechanics of these materials are discussed in the light of theories of deformation for glassy polymers. The experimental data from this study are compared with PMMA results from the literature as well as epoxy-based composites with identical particulates. The PMMA exhibited the expected strain rate and temperature dependence and brittle failure was observed at the highest strain rates and lowest temperatures. The Al–Ni–PMMA composites were found to have similar stress–strain response to the PMMA with reduced strain softening after yield. Increasing volume fraction of particulates in the composite resulted in decreased strength. PMID:24711495

  4. Ability of paramedics to perform endotracheal intubation during continuous chest compressions: a randomized cadaver study comparing Pentax AWS and Macintosh laryngoscopes.

    PubMed

    Truszewski, Zenon; Czyzewski, Lukasz; Smereka, Jacek; Krajewski, Paweł; Fudalej, Marcin; Madziala, Marcin; Szarpak, Lukasz

    2016-09-01

    The aim of the trial was to compare the time parameters for intubation with the use of the Macintosh (MAC) laryngoscope and Pentax AWS-S100 videolaryngoscope (AWS; Pentax Corporation, Tokyo, Japan) with and without chest compression (CC) by paramedics during simulated cardiopulmonary resuscitation in a cadaver model. This was a randomized crossover cadaver trial. Thirty-five paramedics with no experience in videolaryngoscopy participated in the study. They performed intubation in two emergency scenarios: scenario A, normal airway without CC; scenario B, normal airway with continuous CC. The median time to first ventilation with the use of the AWS and the MAC was similar in scenario A: 25 (IQR, 22-27) seconds vs. 24 (IQR, 22.5-26) seconds (P=.072). A statistically significant difference in TTFV between AWS and MAC was noticed in scenario B (P=.011). In scenario A, the first endotracheal intubation (ETI) attempt success rate was achieved in 97.1% with AWS compared with 94.3% with MAC (P=.43). In scenario B, the success rate after the first ETI attempt with the use of the different intubation methods varied and amounted to 88.6% vs. 77.1% for AWS and MAC, respectively (P=.002). The Pentax AWS offered a superior glottic view as compared with the MAC laryngoscope, which was associated with a higher intubation rate and a shorter intubation time during an uninterrupted CC scenario. However, in the scenario without CC, the results for AWS and MAC were comparable. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Objective Measurement of Adherence to Out-Patient Airway Clearance Therapy by High-Frequency Chest Wall Compression in Cystic Fibrosis.

    PubMed

    Mikesell, Christina L; Kempainen, Robert R; Laguna, Theresa A; Menk, Jeremiah S; Wey, Andrew R; Gaillard, Philippe R; Regelmann, Warren E

    2017-07-01

    Objective measures of adherence to high-frequency chest wall compression (HFCWC), a form of airway clearance therapy for patients with cystic fibrosis, are lacking. We used a novel electronic monitoring device integrated into an HFCWC vest to measure adherence compared with self-reported adherence. We determined factors that influenced adherence and how adherence correlated with baseline pulmonary function and pulmonary exacerbations. Data were collected by direct measurement of date, time of day, and duration of HFCWC use to determine the number of daily treatments and daily duration of treatments. Chart review provided prescribed airway clearance therapy treatment and demographic and clinical information. Subject and caregiver report of the daily number of airway clearance therapy treatments was obtained by telephone interviews. Analysis used 2-sample and paired t test, analysis of variance, and linear regression. Average adherence was 69%. Adherence was highest in children (82%, P = .02) and those receiving assistance with treatment (82%, P < .001). Subjects overestimated therapy duration from a mean ± SD of 127 ± 169% by adults to 19.2 ± 26.3% by parents or guardians of children. Average adherence decreased with increasing prescribed therapy time (P = .02). Average daily therapy time and adherence had significant positive associations with baseline FEV1 percent of predicted (P = .02 and P = .02, respectively) and negative associations with pulmonary exacerbations during the pre-study period and at baseline (P = .044 and P = .02, respectively). Greater adherence to HFCWC measured directly by a novel recorder was associated with better baseline pulmonary function and fewer exacerbations in the pre-study and baseline period. Adherence decreased with age and prescribed therapy time and increased with therapy assistance. Self-report overestimation is large and thus not an accurate measure of adherence. Copyright © 2017 by Daedalus Enterprises.

  6. Blunt Chest Trauma in Mice after Cigarette Smoke-Exposure: Effects of Mechanical Ventilation with 100 % O2

    PubMed Central

    Wagner, Katja; Gröger, Michael; McCook, Oscar; Scheuerle, Angelika; Asfar, Pierre; Stahl, Bettina; Huber-Lang, Markus; Ignatius, Anita; Jung, Birgit; Duechs, Matthias; Möller, Peter; Georgieff, Michael; Calzia, Enrico; Radermacher, Peter; Wagner, Florian

    2015-01-01

    Cigarette smoking (CS) aggravates post-traumatic acute lung injury and increases ventilator-induced lung injury due to more severe tissue inflammation and apoptosis. Hyper-inflammation after chest trauma is due to the physical damage, the drop in alveolar PO2, and the consecutive hypoxemia and tissue hypoxia. Therefore, we tested the hypotheses that 1) CS exposure prior to blunt chest trauma causes more severe post-traumatic inflammation and thereby aggravates lung injury, and that 2) hyperoxia may attenuate this effect. Immediately after blast wave-induced blunt chest trauma, mice (n=32) with or without 3-4 weeks of CS exposure underwent 4 hours of pressure-controlled, thoraco-pulmonary compliance-titrated, lung-protective mechanical ventilation with air or 100 % O2. Hemodynamics, lung mechanics, gas exchange, and acid-base status were measured together with blood and tissue cytokine and chemokine concentrations, heme oxygenase-1 (HO-1), activated caspase-3, and hypoxia-inducible factor 1-α (HIF-1α) expression, nuclear factor-κB (NF-κB) activation, nitrotyrosine formation, purinergic receptor 2X4 (P2XR4) and 2X7 (P2XR7) expression, and histological scoring. CS exposure prior to chest trauma lead to higher pulmonary compliance and lower PaO2 and Horovitz-index, associated with increased tissue IL-18 and blood MCP-1 concentrations, a 2-4-fold higher inflammatory cell infiltration, and more pronounced alveolar membrane thickening. This effect coincided with increased activated caspase-3, nitrotyrosine, P2XR4, and P2XR7 expression, NF-κB activation, and reduced HIF-1α expression. Hyperoxia did not further affect lung mechanics, gas exchange, pulmonary and systemic cytokine and chemokine concentrations, or histological scoring, except for some patchy alveolar edema in CS exposed mice. However, hyperoxia attenuated tissue HIF-1α, nitrotyrosine, P2XR7, and P2XR4 expression, while it increased HO-1 formation in CS exposed mice. Overall, CS exposure aggravated post

  7. Comparison of changes in tidal volume associated with expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation

    PubMed Central

    Morino, Akira; Shida, Masahiro; Tanaka, Masashi; Sato, Kimihiro; Seko, Toshiaki; Ito, Shunsuke; Ogawa, Shunichi; Takahashi, Naoaki

    2015-01-01

    [Purpose] This study was designed to compare and clarify the relationship between expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation, with a focus on tidal volume. [Subjects and Methods] The subjects were 18 patients on prolonged mechanical ventilation, who had undergone tracheostomy. Each patient received expiratory rib cage compression and expiratory abdominal compression; the order of implementation was randomized. Subjects were positioned in a 30° lateral recumbent position, and a 2-kgf compression was applied. For expiratory rib cage compression, the rib cage was compressed unilaterally; for expiratory abdominal compression, the area directly above the navel was compressed. Tidal volume values were the actual measured values divided by body weight. [Results] Tidal volume values were as follows: at rest, 7.2 ± 1.7 mL/kg; during expiratory rib cage compression, 8.3 ± 2.1 mL/kg; during expiratory abdominal compression, 9.1 ± 2.2 mL/kg. There was a significant difference between the tidal volume during expiratory abdominal compression and that at rest. The tidal volume in expiratory rib cage compression was strongly correlated with that in expiratory abdominal compression. [Conclusion] These results indicate that expiratory abdominal compression may be an effective alternative to the manual breathing assist procedure. PMID:26311963

  8. Nucleation and growth mechanisms of hcp domains in compressed iron.

    PubMed

    Pang, Wei-Wei; Zhang, Ping; Zhang, Guang-Cai; Xu, Ai-Guo; Zhao, Xian-Geng

    2014-06-12

    In our previous work, we have pointed out that the shock-induced phase transition in iron occurs with the help of interface energy which reduces the potential barrier between two phases. Here, through studying the nucleation and growth mechanisms of hcp domains in compressed iron, we find that the flatted-octahedral-structure (FOS) is the primary structural unit of the embryo nucleus and phase interface of hcp domains, and the interfacial energy is reduced via formation of FOSs. The phase transition process can be described by the following four stages: (i) Some atoms deviate from their equilibrium positions with the aid of thermal fluctuations to form FOSs with two different deformation directions in the local region; (ii) FOSs with different deformation directions aggregate to form a thin stratified structure like twin-crystal configuration; (iii) The thin stratified structure undergoes a relative slip to form the new hcp phase; (iv) The hcp phase domain grows up through the formation of new FOSs along the phase boundary. In addition, through comparing the time evolution curves of initial single phase domain, we find that the growth rate of single phase domain depends on the loading way and its occurrence time.

  9. Mechanical analysis of PA66 under combined shear-compression

    NASA Astrophysics Data System (ADS)

    Duan, Qian; Jin, Tao; Chen, Shengjia; Shu, Xuefeng

    2017-05-01

    The large-strain mechanical behavior of PA66 was investigated using shear-compression specimens (SCS) with two opposite slots machined at different angles (15°, 30°, 45°, and 50°). Results show that strain rate and slot angle affect the equivalent stress in different levels. Slot angle sensitivity affects both flow stress and hardening characteristics, and strain rate influences elastic deformation. Increasing the strain rate gradually increases the equivalent stress. SCS with a slot angle of 30° exhibits the largest equivalent stress and the greatest effect of strain rate. The stress-strain curve differs between cylindrical specimens and SCS under quasi-static conditions. The yield stress obtained by the cylindrical specimens is higher than that of SCS. A constitutive model is modified based on the Drucker-Prager criterion to describe the effect of hydrostatic pressure and strain rate on the equivalent yield stress of polymer materials. The theoretical formula predictions are consistent with experimental results, thereby confirming the feasibility of this constitutive relationship.

  10. Influence of static compression on mechanical parameters of acoustic foams.

    PubMed

    Geslain, A; Dazel, O; Groby, J-P; Sahraoui, S; Lauriks, W

    2011-08-01

    The modification of elastic properties of compressed acoustic foams is investigated. The porous sample is first submitted to a static compression and then to a dynamic excitation of smaller amplitude, corresponding to acoustical applications. The static compression induces the modification of the dynamic elastic parameters of the material. This work focuses on Young's modulus. The variation is measured with two different experimental methods: The classical rigidimeter and an absorption measurement. The effective Young's modulus is directly measured with the first method and is indirectly determined through the quarter-wave length resonance of the frame with the second one. The results of the two measurements are compared and give similar tendencies. The variation of the dynamic Young's modulus as a function of the degree of compression of the sample is shown to be separated in several zones. In the zones associated with weak compression (those usually zones encountered in practice), the variation of the effective Young's modulus can be approximated by a simple affine function. The results are compared for different foams. A simple model of the dependency of the Young's modulus with respect to the static degree of compression is finally proposed for weak compressions.

  11. A non-topological mechanism for negative linear compressibility.

    PubMed

    Binns, Jack; Kamenev, Konstantin V; Marriott, Katie E R; McIntyre, Garry J; Moggach, Stephen A; Murrie, Mark; Parsons, Simon

    2016-06-14

    Negative linear compressibility (NLC), the increase in a unit cell length with pressure, is a rare phenomenon in which hydrostatic compression of a structure promotes expansion along one dimension. It is usually a consequence of crystal structure topology. We show that the source of NLC in the Co(ii) citrate metal-organic framework UTSA-16 lies not in framework topology, but in the relative torsional flexibility of Co(ii)-centred tetrahedra compared to more rigid octahedra.

  12. [Effect of chest physiotherapy in patients undergoing mechanical ventilation: a prospective randomized controlled trial].

    PubMed

    Zeng, Hui; Zhang, Zhen; Gong, Yuan; Chen, Miao

    2017-05-01

    To investigate the effect of chest physiotherapy (CPT) on patients undergoing mechanical ventilation (MV). A prospective randomized controlled trial (RCT) was conducted. Sixty-eight adult patients undergoing invasive MV over 48 hours admitted to intensive care unit (ICU) of Affiliated Hospital of Zunyi Medical College from December 2014 to October 2016 were enrolled, and they were divided into CPT group (n = 37) and control group (n = 31) by random number table. The patients in control group received routine physical therapy; while those in the CPT group received comprehensive CPT including manual lung inflation, vibration expectoration and early functional exercise etc. on the basis of the treatment in control group. Acute physiology and chronic health evaluation II (APACHE II) score and oxygenation index (PaO2/FiO2) before and after the treatment in both two groups were observed as well as the respiratory function and vital signs before and after CPT. The laboratory indicators after treatment, incidence of complications, duration of MV and the length of ICU stay in the two groups were recorded. The incidence of ventilator associated pneumonia (VAP) in the CPT group was significantly lower than that of control group (5.4% vs. 25.8%, P < 0.05), the patients in control group also had atelectasis, deep vein thrombosis and other complications, while no such complications were found in the CPT group. The duration of MV (hours: 77.4±41.0 vs. 133.9±117.2) and the length of ICU stay (hours: 134.4±71.4 vs. 207.4±177.7) in CPT group were significantly shorter than those of the control group (both P < 0.05). There was no significant difference in APACHE II score and PaO2/FiO2 before treatment between the two groups. After treatment for 2 days, the APACHE II score in both groups was gradually decreased, and that in CPT group was more significantly, it was significantly lower than that of control group after treatment for 4 days (8.6±3.9 vs. 12.5±5.3, P < 0.05). The PaO2

  13. Chest pain

    MedlinePlus

    ... have a fever or a cough that produces yellow-green phlegm. You have chest pain that is severe and does not go away. You are having problems swallowing. Chest pain lasts longer than 3 to 5 days. What to Expect at Your Office Visit ...

  14. [Chest pain].

    PubMed

    Horn, Benedikt

    2015-01-01

    Chest pain in ambulatory setting is predominantly not heart-associated. Most patients suffer from muskuloskeletal or functional (psychogenic) chest pain. Differential diagnosis covers aortic dissection, rib-fracture, shingles, GERD, Tietze-Syndrome, pulmonary embolism, pleuritis, pneumothorax, pleurodynia and metastatic disease. In most cases history, symptoms and signs allow a clinical diagnosis of high pretest-probability.

  15. A method for intermediate strain rate compression testing and study of compressive failure mechanism of Mg-Al-Zn alloy

    NASA Astrophysics Data System (ADS)

    Gupta, Nikhil; Luong, Dung D.; Rohatgi, Pradeep K.

    2011-05-01

    Obtaining meaningful information from the test results is a challenge in the split-Hopkinson pressure bar (SHPB) test method if the specimen does not fail during the test. Although SHPB method is now widely used for high strain rate testing, this limitation has made it difficult to use it for characterization of materials in the intermediate strain rate range (typically 10-1000 s-1). In the present work, a method is developed to characterize materials in the intermediate strain rate range using SHPB setup. In this method, the specimen is repeatedly tested under compression at a given strain rate until failure is achieved. The stress-strain graphs obtained from each test cycle are used to plot the master stress-strain graph for that strain rate. This method is used to study the strain rate dependence of compressive response of a Mg-Al-Zn alloy in the intermediate strain rate range. A remarkable difference is observed in the failure mechanism of the alloy under quasi-static and intermediate strain rate compression. Matrix cracking is the main failure mechanism under quasi-static compression, whereas shattering of intermetallic precipitates, along with plastic deformation of the matrix, is discovered to become prominent as the strain rate is increased.

  16. Parameters affecting the tidal volume during expiratory abdominal compression in patients with prolonged tracheostomy mechanical ventilation

    PubMed Central

    Morino, Akira; Shida, Masahiro; Tanaka, Masashi; Sato, Kimihiro; Seko, Toshiaki; Ito, Shunsuke; Ogawa, Shunichi; Takahashi, Naoaki

    2015-01-01

    [Purpose] The aim of this study was to clarify physical parameters affecting the tidal volume during expiratory abdominal compression in patients with prolonged tracheostomy mechanical ventilation. [Methods] Eighteen patients with prolonged mechanical ventilation were included in this study. Expiratory abdominal compression was performed on patients lying in a supine position. The abdomen above the navel was vertically compressed in synchronization with expiration and released with inspiration. We measured the tidal volume during expiratory abdominal compression. [Results] The mean tidal volume during expiratory abdominal compression was higher than that at rest (430.6 ± 127.1 mL vs. 344.0 ± 94.3 mL). The tidal volume during expiratory abdominal compression was correlated with weight, days of ventilator support, dynamic compliance and abdominal expansion. Stepwise multiple regression analysis revealed that weight (β = 0.499), dynamic compliance (β = 0.387), and abdominal expansion (β = 0.365) were factors contributing to the tidal volume during expiratory abdominal compression. [Conclusion] Expiratory abdominal compression increased the tidal volume in patients with prolonged tracheostomy mechanical ventilation. The tidal volume during expiratory abdominal compression was influenced by each of the pulmonary conditions and the physical characteristics. PMID:26311947

  17. Mechanical properties of human enamel under compression: On the feature of calculations.

    PubMed

    Zaytsev, Dmitry

    2016-05-01

    The paper is aimed at determination of the causes of shape effect in human tooth enamel under compression and correction of the relevant mechanical characteristics. For this purpose, six groups of samples with different ratios of the compression surface diagonal to the sample height, which consisted of 10 cuboid samples in each, were prepared from the backside of human enamel. The lateral deformation of a sample was calculated at the maximum compressive stress for correction of the mechanical characteristics. It is shown that the ratio between the lateral and axial deformations decreases with an increase in the ratio of the compression surface diagonal to the sample height. This is caused by the friction between the compression plates and the working surfaces of the enamel sample when the lateral deformation is suppressed. In addition, the slope of enamel sample by about 15° occurred during compression due to the inclination of rigid and low deformable enamel rods. The corrections of the elastic modulus and the compression strength taking into account the lateral deformation and the sample slope are carried out. The mechanical properties of enamel samples with the 2.1 aspect ratio are closer to the intrinsic properties of human enamel samples. The elastic modulus and the compression strength of human enamel under compression are 5.64 GPa and 363 MPa, respectively. The lateral deformation (~10%) may be considered as the critical parameter that indicates the strength of human enamel.

  18. Deformation and failure mechanisms of braided composite tubes in compression and torsion

    SciTech Connect

    Harte, A.M.; Fleck, N.A.

    2000-04-03

    The deformation and fracture behavior of glass fibre-epoxy braided circular tubes is examined experimentally and theoretically for the loading cases of compression, torsion, and combined tension-torsion and compression-torsion. Failure maps are produced for compression and for torsion to summarize the effect of braid microstructure upon failure mode and upon the mechanical properties of the braid, including yield strength, modulus, strain to failure and energy absorption. In compression, two competing mechanisms are observed: diamond shaped buckling of the tube and fibre microbuckling. In torsion and in combined compression-torsion, the tubes fail by fibre microbuckling. The initiation and propagation stresses for diamond shaped buckling, and the critical stress for fibre microbuckling are successfully predicted using simple micromechanical models. Drawing upon the available experimental data, yield surfaces are constructed for in-plane loading of the braid, and a comprehensive mechanism map is constructed to illustrate the dependence of failure mode upon braid geometry and loading direction.

  19. Effects of mechanical stimulation induced by compression and medium perfusion on cardiac tissue engineering.

    PubMed

    Shachar, Michal; Benishti, Nessi; Cohen, Smadar

    2012-01-01

    Cardiac tissue engineering presents a challenge due to the complexity of the muscle tissue and the need for multiple signals to induce tissue regeneration in vitro. We investigated the effects of compression (1 Hz, 15% strain) combined with fluid shear stress (10(-2) -10(-1) dynes/cm(2) ) provided by medium perfusion on the outcome of cardiac tissue engineering. Neonatal rat cardiac cells were seeded in Arginine-Glycine-Aspartate (RGD)-attached alginate scaffolds, and the constructs were cultivated in a compression bioreactor. A daily, short-term (30 min) compression (i.e., "intermittent compression") for 4 days induced the formation of cardiac tissue with typical striation, while in the continuously compressed constructs (i.e., "continuous compression"), the cells remained spherical. By Western blot, on day 4 the expression of the gap junction protein connexin 43 was significantly greater in the "intermittent compression" constructs and the cardiomyocyte markers (α-actinin and N-cadherin) showed a trend of better preservation compared to the noncompressed constructs. This regime of compression had no effect on the proliferation of nonmyocyte cells, which maintained low expression level of proliferating cell nuclear antigen. Elevated secretion levels of basic fibroblast growth factor and transforming growth factor-β in the daily, intermittently compressed constructs likely attributed to tissue formation. Our study thus establishes the formation of an improved cardiac tissue in vitro, when induced by combined mechanical signals of compression and fluid shear stress provided by perfusion.

  20. Chest Pain

    MedlinePlus

    ... causes Chest pain can also be caused by: Panic attack. If you have periods of intense fear accompanied ... fear of dying, you may be experiencing a panic attack. Shingles. Caused by a reactivation of the chickenpox ...

  1. Instantaneous responses to high-frequency chest wall oscillation in patients with acute pneumonic respiratory failure receiving mechanical ventilation

    PubMed Central

    Chuang, Ming-Lung; Chou, Yi-Ling; Lee, Chai-Yuan; Huang, Shih-Feng

    2017-01-01

    Abstract Background: Endotracheal intubation and prolonged immobilization of patients receiving mechanical ventilation may reduce expectoration function. High-frequency chest wall oscillation (HFCWO) may ameliorate airway secretion movement; however, the instantaneous changes in patients’ cardiopulmonary responses are unknown. Moreover, HFCWO may influence ventilator settings by the vigorous oscillation. The aim of this study was to investigate these issues. Methods: Seventy-three patients (52 men) aged 71.5 ± 13.4 years who were intubated with mechanical ventilation for pneumonic respiratory failure were recruited and randomly classified into 2 groups (HFCWO group, n = 36; and control group who received conventional chest physical therapy (CCPT, n = 37). HFCWO was applied with a fixed protocol, whereas CCPT was conducted using standard protocols. Both groups received sputum suction after the procedure. Changes in ventilator settings and the subjects’ responses were measured at preset intervals and compared within groups and between groups. Results: Oscillation did not affect the ventilator settings (all P > 0.05). The mean airway pressure, breathing frequency, and rapid shallow breathing index increased, and the tidal volume and SpO2 decreased (all P < 0.05). After sputum suction, the peak airway pressure (Ppeak) and minute ventilation decreased (all P < 0.05). The HFCWO group had a lower tidal volume and SpO2 at the end of oscillation, and lower Ppeak and tidal volume after sputum suction than the CCPT group. Conclusions: HFCWO affects breathing pattern and SpO2 but not ventilator settings, whereas CCPT maintains a steadier condition. After sputum suction, HFCWO slightly improved Ppeak compared to CCPT, suggesting that the study extends the indications of HFCWO for these patients in intensive care unit. (ClinicalTrials.gov number NCT02758106, retrospectively registered.) PMID:28248854

  2. Chest X-Ray (Chest Radiography)

    MedlinePlus

    ... News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Chest Chest x-ray uses a very ... limitations of Chest Radiography? What is a Chest X-ray (Chest Radiography)? The chest x-ray is the ...

  3. [Behavior of the lung mechanics after the application of protocol of chest physiotherapy and aspiration tracheal in patients with invasive mechanical ventilation].

    PubMed

    Rosa, Fernanda Kusiak da; Roese, Cláudia Adegas; Savi, Augusto; Dias, Alexandre Simões; Monteiro, Mariane Borba

    2007-06-01

    The chest physiotherapy (CP) in patients submitted to invasive support ventilation acts directly in the breathing system, and it could alter the lung mechanics through the dynamic lung compliance (DynC) and resistance of the breathing system (Rbs). However the alterations after the accomplishment of CP are still controversy. The objective of this study was to evaluate the alterations of the lung mechanics in patients in invasive mechanical ventilation (IMV). It was a prospective, randomized, and controlled and crossover study, with patient with more than 48 hours in IMV. The protocol of chest physiotherapy and isolated tracheal aspiration they were randomized for the application order with a window of 24 hours among them. Data of lung mechanics and its varied cardiorespiratory were collected moments before the protocol, immediately after the application of the protocol, 30 minutes and 120 minutes after the application of the protocols. Twelve patients completed the study. Pneumonia was the mean cause respiratory failure (RF). There was not statistical difference among the groups in relation to Cdyn, volume tidal (Vt) and volume minute (Ve). Rbs decreased in a significant way immediately after (of 10.4 ± 3 cmH2O/L/seg for 8.9 ± 2 cmH2O/L/seg; p < 0.02), 30 minutes after (of 10.4 ± 3 cmH2O/L/seg for 9 ± 2 cmH2O/L/seg; p < 0.01) and 120 minutes after (of 10.4 ± 3 cmH2O/L/seg for 9 ± 2 cmH2O/L/seg; p < 0.03) application the protocol of chest physiotherapy. When compared with the protocol of isolated tracheal aspiration it was significantly smaller in the 30 (9 ± 2 cmH2O/L/seg versus10.2 ± 2 cmH2O/L/seg; p < 0.04) and 120 minutes (9 ± 2 cmH2O/L/seg versus 10.4 ± 3 cmH2O/L/seg; p < 0.04). The protocol of chest physiotherapy was effective in the decrease of Rsr when compared with the aspiration protocol. That decrease was maintained for two hours after its application, what did not happen when only the just accomplished the tracheal aspiration was performed

  4. Tensile and compressive mechanical behavior of twinned silicon carbide nanowires

    SciTech Connect

    Wang, Zhiguo; Li, Jingbo; Gao, Fei; Weber, William J.

    2010-04-01

    Molecular dynamics simulations with the Tersoff potential were used to study the response of twinned SiC nanowires under tensile and compressive strains. The critical strain of the twinned nanowires can be enhanced by twin-stacking faults, and their critical strains are larger than those of perfect nanowires with the same diameters. Under axial tensile strain, the bonds of the nanowires are just stretched before failure. The failure behavior is found to depend on the twin segment thickness and the diameter of the nanowires. An atomic chain is observed for the thin nanowires with small twin segment thickness under tension strain. Under axial compressive strain, the collapse of the twinned SiC nanowires exhibits two differently failure modes, depending on the length and diameter of the nanowires, i.e. shell buckling for short length nanowires and columnar buckling for longer length nanowires.

  5. Automatic compression adjusting mechanism for internal combustion engines

    NASA Technical Reports Server (NTRS)

    Akkerman, J. W. (Inventor)

    1983-01-01

    Means for controlling the compression pressure in an internal combustion engine having one or more cylinders and subject to widely varying power output requirements are provided. Received between each crank pin and connecting rod is an eccentric sleeve selectively capable of rotation about the crank pin and/or inside the rod and for latching with the rod to vary the effective length of the connecting rod and thereby the clearance volume of the engine. The eccentric normally rotates inside the connecting rod during the exhaust and intake strokes but a latching pawl carried by the eccentric is movable radially outwardly to latch the rod and eccentric together during the compression and power strokes. A control valve responds to intake manifold pressure to time the supply of hydraulic fluid to move the latch-pawl outwardly, varying the effective rod length to maintain a substantially optimum firing chamber pressure at all intake manifold pressures.

  6. Mechanical behavior and failure mechanism of pre-cracked specimen under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Liu, Ting; Lin, Baiquan; Yang, Wei

    2017-08-01

    As a desirable permeability enhancement method, hydraulic slotting has been widely used for enhanced coal bed methane (ECBM) recovery in China. Aiming at the problem that the action mechanism of the slot on the mechanical properties of the slotted coal is still unclear, this paper investigates the effects of flaw inclination on the strength, deformation and cracking process of the pre-cracked specimens. The result shows that the stress-strain curves can be divided into three categories based on the stress behaviors, dropping step by step or dropping sharply, after the peak. With an increase of the flaw inclination, the strength and elastic modulus of the pre-cracked specimen increases gradually, which is verified by the numerical simulation and theoretical results. Analysis of the cracking processes indicates that the initiation position of the first crack in specimens with various flaw inclinations is different, which is caused by the various distributions of tensile and compressive stress concentration zones. The distribution of the stress field controls the cracking process which will in turn affect the stress field distribution. With the propagation of the cracks, the tensile stress concentration zones expand and the concentration degree lowers gradually, while the compressive stress concentration zones show the opposite variation trend. Based on the above results, an optimized slot arrangement method has been proposed for the field application of hydraulic slotting.

  7. On the mechanical behavior of slender, slightly curved, compressed microbridges

    NASA Astrophysics Data System (ADS)

    Hallauer, W. L.; Ma, C.

    2011-06-01

    We consider a clamped-clamped, slender beam-column that is slightly curved in its unloaded static equilibrium state. Perhaps the best practical example of this type of structure is a microbeam used in sensing and actuating devices. If the clamped ends are forced toward each other, or if stiff supports inhibit axial expansion that is fostered by fabrication processes and/or operational heating, then the column bends beyond its initial curvature. If the axial force approaches the buckling load, then the static flexural deflection can be relatively large, greater than the column's depth. We show that the dependence of moderately large static deflection upon compressive force is mathematically linear, and that nonlinearity arises only in the relationship of column shortening to transverse deflection. This leads to a linear finite-element method for static structural analysis of non-uniform columns, with which we simulate the behavior of a 62.5 µm long microbridge of 0.5 µm thin-film gold. This microbridge was observed experimentally to bend 4-5 µm under compression. We also examine previous studies of bending vibration about moderately large static deflection. Calculations and experimental measurements of the dependence of the fundamental natural frequency on axial compression and initial curvature indicate practical significance relative to design of microbridge resonators.

  8. Hybrid Vapor Compression Ejector Cycle: Presentation to IAPG Mechanical Working Group

    DTIC Science & Technology

    2011-08-01

    Compression Ejector Cycle: Presentation to IAPG Mechanical Working Group Parmesh Verma and Tom Radcliff, United Technologies Research Center UNCLASSIFIED... Ejector Cycle Presentation to IAPG Mechanical Working Group 5a. CONTRACT NUMBER W909MY-10-C-0005 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...hybrid vapor compression ejector heat pump cycle developed under an American Recovery and Reinvestment Act funded contract is provided. 15. SUBJECT

  9. Impacts to the chest of PMHSs - Influence of impact location and load distribution on chest response.

    PubMed

    Holmqvist, Kristian; Svensson, Mats Y; Davidsson, Johan; Gutsche, Andreas; Tomasch, Ernst; Darok, Mario; Ravnik, Dean

    2016-02-01

    The chest response of the human body has been studied for several load conditions, but is not well known in the case of steering wheel rim-to-chest impact in heavy goods vehicle frontal collisions. The aim of this study was to determine the response of the human chest in a set of simulated steering wheel impacts. PMHS tests were carried out and analysed. The steering wheel load pattern was represented by a rigid pendulum with a straight bar-shaped front. A crash test dummy chest calibration pendulum was utilised for comparison. In this study, a set of rigid bar impacts were directed at various heights of the chest, spanning approximately 120mm around the fourth intercostal space. The impact energy was set below a level estimated to cause rib fracture. The analysed results consist of responses, evaluated with respect to differences in the impacting shape and impact heights on compression and viscous criteria chest injury responses. The results showed that the bar impacts consistently produced lesser scaled chest compressions than the hub; the Middle bar responses were around 90% of the hub responses. A superior bar impact provided lesser chest compression; the average response was 86% of the Middle bar response. For inferior bar impacts, the chest compression response was 116% of the chest compression in the middle. The damping properties of the chest caused the compression to decrease in the high speed bar impacts to 88% of that in low speed impacts. From the analysis it could be concluded that the bar impact shape provides lower chest criteria responses compared to the hub. Further, the bar responses are dependent on the impact location of the chest. Inertial and viscous effects of the upper body affect the responses. The results can be used to assess the responses of human substitutes such as anthropomorphic test devices and finite element human body models, which will benefit the development process of heavy goods vehicle safety systems. Copyright © 2015

  10. Mechanical behaviour of selected bulk oilseeds under compression loading

    NASA Astrophysics Data System (ADS)

    Mizera, Č.; Herák, D.; Hrabě, P.; Aleš, Z.; Pavlů, J.

    2017-09-01

    Pressing of vegetable oils plays an important role in modern agriculture. This study was focused on the linear pressing of soybean seeds (Glycine max L.), Jatropha seeds (Jatropha curcas L.) and palm kernel (Elaeisguineensis). For pressing test the compressive device (ZDM, model 50, Germany) was used. The maximum pressing force of 100 kN with a compression speed of 1 mm s-1 was used to record the force-deformation characteristics. The pressing vessel with diameter 60 mm and initial height of seeds 80 mm were used. The specific energy per gram of oil of soybean, palm kernel and Jatropha was 158.92 ± 7.21, 128.78 ± 8.36 and 68.26 ± 5.94 J.goil-1, respectively. The oil content of soybean, palm kernel and Jatropha was 20.4 ± 1.23, 44.7 ± 2.27 and 34.2 ± 1.75 %, respectively. Water concentration, dynamic and kinematic viscosity of obtained oils was also determined.

  11. Pediatric Mechanical Support with an External Cardiac Compression Device

    PubMed Central

    Kavarana, Minoo N; Loree, Howard M; Stewart, Robert B; Milbocker, Michael T; Hannan, Robert L; Pantalos, George M; Kung, Robert TV

    2013-01-01

    The PediBooster external cardiac compression device is a minimally invasive, non-blood contacting Biventricular Assist Device (BiVAD) intended for pediatric use. It is being developed as a palliative therapy for acute Postcardiotomy Shock (PCS). The PediBooster extracardiac wrap is pneumatically actuated to circumferentially compress the heart, providing co-pulsation support. Attachment is via a novel hydrogel coating. Early versions of the wrap were tested in vivo using a single ventricle congenital heart disease model with postcardiotomy shock, which proved unstable and demonstrated high peri-operative mortality. The final wrap design was tested in 4 acute studies with piglets (5.1 ± 0.3 kg), where the combination of ASD and PA banding induced acute right ventricular dysfunction. Data collected included routine hemodynamic values, TEE, video of the exposed heart, and cardiac histology. The model proved stable for support durations ranging from 2 to 16 hours. The wrap restricted the heart in 3 of the 4 animals, as evidenced by increased diastolic LVP during support compared to the baseline failure condition. TEE and video data showed good attachment and function of the wrap, particularly during the final 16 hr study. This model of congenital heart disease shows promise for chronic (24-72 hr) studies. Ventricular filling during support may be improved by adjusting wrap dimensions to eliminate end diastolic restriction. PMID:24040624

  12. Chest Diseases

    PubMed Central

    Balmes, John R.

    1992-01-01

    The Council on Scientific Affairs of the California Medical Association presents the following inventory of items of progress in chest diseases. Each item, in the judgment of a panel of knowledgeable physicians, has recently become reasonably firmly established, both as to scientific fact and important clinical significance. The items are presented in simple epitome, and an authoritative reference, both to the item itself and to the subject as a whole, is generally given for those who may be unfamiliar with a particular item. The purpose is to assist busy practitioners, students, researchers, or scholars to stay abreast of these items of progress in chest diseases that have recently achieved a substantial degree of authoritative acceptance, whether in their own field of special interest or another. The items of progress listed below were selected by the Advisory Panel to the Section on Chest Diseases of the California Medical Association, and the summaries were prepared under its direction. PMID:1441468

  13. Chest trauma.

    PubMed

    Budassi, S A

    1978-09-01

    For any patient with obvious or suspected chest trauma, one must first assure an adequate airway and adequate ventilation. One should never hesitate to administer oxygen to a victim with a chest injury. The nurse should be concerned with adequate circulation--this may mean the administration of intravenous fluids, specifically volume expanders, via large-bore cannulae. Any obvious open chest wound should be sealed, and any fractures should be splinted. These patients should be rapidly transported to the nearest Emergency Department capable of handling this type of injury. The majority of patients who arrive in the Emergency Department following blunt or penetrating trauma should be considered to be in critical condition until proven otherwise. On presentation, it is essential to recognize those signs, symptoms, and laboratory values that identify the patient's condition as life-threatening. Simple recognition of these signs and symptoms and early appropriate intervention may alter an otherwise fatal outcome.

  14. The compression mechanism of garnets based on in situ observations

    NASA Astrophysics Data System (ADS)

    Dymshits, Anna; Sharygin, Igor; Litasov, Konstantin; Shatskiy, Anton

    2014-05-01

    Previously it was showed that the bulk modulus of garnet is strongly affected by the bulk modulus of the dodecahedra, while compressibility of other individual polyhedra displays no correlation with the compressibility of the structure as a whole (Milman et al., 2001). If so, Na-majorite (Na-maj) would have the smallest bulk modulus of all silicate garnets, as a phase with a predicted dodecahedral bulk modulus of approximately 70 GPa (Hazen et al., 1994). In fact Na-maj has the largest bulk modulus among the silicate garnets. This behavior must reflect the all-mineral framework of Na-maj with very small cell volume and silicon in the octahedral position. Thus, we conclude that not only the dodecahedral sites, but also the behavior of the garnet framework and relative sizes of the 8- and 6-coordinated cations, control garnet compression. The octahedral site in Na-maj is quite small (1.79 Å) and contains only silicon in comparison to the pyrope (1.85 Å) or majorite (1.88 Å). The small and highly charged octahedra shares four edges with the dodecahedra and thus restrict the volume of the large and low charged dodecahedra. In spite Na-maj has a large average X-cation radius (RNa = 1.07 Å) its dodecahedral volume is relatively small (V = 21.23 and 21.26 Å3). Pacalo et al. (1992) suggested that XO8 polyhedra act as braces and controls the amount of rotation between tetrahedra and octahedra within the corner-linked chains. In case of pyrope XO8 cite is not filled up and polyhedra within the corner-linked chains can rotate freely to accommodate applied stress. In case of Na-maj the dodecahedral site is filled up and rotational freedom is minimized. The dodecahedral site in knorringite (Knr) contains cation with a small radius (Mg-O = 2.22 and 2.34 Å), so XO8 polyhedra is not filled up and can rotate freely to accommodate applied stress. In case of uvarovite not only octahedral but the dodecahedral site is also large (Ca-O = 2.35 and 2.51 Å), so the rotational

  15. Structural basis for the nonlinear mechanics of fibrin networks under compression

    PubMed Central

    Kim, Oleg V.; Litvinov, Rustem I.; Weisel, John W.; Alber, Mark S.

    2014-01-01

    Fibrin is a protein polymer that forms a 3D filamentous network, a major structural component of protective physiological blood clots as well as life threatening pathological thrombi. It plays an important role in wound healing, tissue regeneration and is widely employed in surgery as a sealant and in tissue engineering as a scaffold. The goal of this study was to establish correlations between structural changes and mechanical responses of fibrin networks exposed to compressive loads. Rheological measurements revealed nonlinear changes of fibrin network viscoelastic properties under dynamic compression, resulting in network softening followed by its dramatic hardening. Repeated compression/decompression enhanced fibrin clot stiffening. Combining fibrin network rheology with simultaneous confocal microscopy provided direct evidence of structural modulations underlying nonlinear viscoelasticity of compressed fibrin networks. Fibrin clot softening in response to compression strongly correlated with fiber buckling and bending, while hardening was associated with fibrin network densification. Our results suggest a complex interplay of entropic and enthalpic mechanisms accompanying structural changes and accounting for the nonlinear mechanical response in fibrin networks undergoing compressive deformations. These findings provide new insight into the fibrin clot structural mechanics and can be useful for designing fibrin-based biomaterials with modulated viscoelastic properties. PMID:24840618

  16. Structural basis for the nonlinear mechanics of fibrin networks under compression.

    PubMed

    Kim, Oleg V; Litvinov, Rustem I; Weisel, John W; Alber, Mark S

    2014-08-01

    Fibrin is a protein polymer that forms a 3D filamentous network, a major structural component of protective physiological blood clots as well as life threatening pathological thrombi. It plays an important role in wound healing, tissue regeneration and is widely employed in surgery as a sealant and in tissue engineering as a scaffold. The goal of this study was to establish correlations between structural changes and mechanical responses of fibrin networks exposed to compressive loads. Rheological measurements revealed nonlinear changes of fibrin network viscoelastic properties under dynamic compression, resulting in network softening followed by its dramatic hardening. Repeated compression/decompression enhanced fibrin clot stiffening. Combining fibrin network rheology with simultaneous confocal microscopy provided direct evidence of structural modulations underlying nonlinear viscoelasticity of compressed fibrin networks. Fibrin clot softening in response to compression strongly correlated with fiber buckling and bending, while hardening was associated with fibrin network densification. Our results suggest a complex interplay of entropic and enthalpic mechanisms accompanying structural changes and accounting for the nonlinear mechanical response in fibrin networks undergoing compressive deformations. These findings provide new insight into the fibrin clot structural mechanics and can be useful for designing fibrin-based biomaterials with modulated viscoelastic properties.

  17. Joining mechanism with stem tension and interlocked compression ring

    DOEpatents

    James, Allister W.; Morrison, Jay A.

    2012-09-04

    A stem (34) extends from a second part (30) through a hole (28) in a first part (22). A groove (38) around the stem provides a non-threaded contact surface (42) for a ring element (44) around the stem. The ring element exerts an inward force against the non-threaded contact surface at an angle that creates axial tension (T) in the stem, pulling the second part against the first part. The ring element is formed of a material that shrinks relative to the stem by sintering. The ring element may include a split collet (44C) that fits partly into the groove, and a compression ring (44E) around the collet. The non-threaded contact surface and a mating distal surface (48) of the ring element may have conic geometries (64). After shrinkage, the ring element is locked onto the stem.

  18. The mechanical behavior of locking compression plates compared with dynamic compression plates in a cadaver radius model.

    PubMed

    Gardner, Michael J; Brophy, Robert H; Campbell, Deirdre; Mahajan, Amit; Wright, Timothy M; Helfet, David L; Lorich, Dean G

    2005-10-01

    The purpose of this cadaveric study was to compare the mechanical behavior of a locked compression plate, which uses threaded screw heads to create a fixed angle construct, with a dynamic compression plate construct in a cadaver radius model. Mechanical study with cyclic testing and high-speed optical motion analysis. Biomechanics laboratory at an academic institution. Eighteen pairs of fresh-frozen human cadaver radii were divided into 3 groups of 6 to be tested as a group in each of the following force applications: anteroposterior (AP) bending, mediolateral bending, or torsion. Each bone was osteotomized leaving a 5-mm fracture gap and then fixed with a plate. For each pair, 1 radius received a standard plate (limited-contact dynamic compression plates; LC-DCP), the contralateral radius was fixed with a locking compression plate (LCP), and specimens underwent cyclic loading. Normalized stiffness, average energy absorbed, and Newton-cycles to failure were calculated. In addition, a 3-dimensional, high-speed, infrared motion analysis system was used to evaluate motion at the fracture site. Construct stiffness, fracture site motion, cycles to failure, and energy absorption. Repeated measures ANOVA were used to detect differences between groups with time. In the torsion group, LCP specimens failed at 60% greater Newton-cycles than the LC-DCP (1473 vs. 918; P < 0.05). In the AP group, the LC-DCP absorbed significantly greater energy during 10,000 cycles compared with the LCP group (P < 0.05). The 2 constructs demonstrated different biomechanical behavior with time. As cycling progressed in the LC-DCP specimens under torsion testing, stiffness (measured at the actuator at the bone ends) did not change significantly; however, fracture motion (measured at the fracture surfaces) decreased significantly (P = 0.04). The LCP specimens did not display similar behavior. Our findings indicated that LCP constructs may demonstrate subtle mechanical superiority compared with the

  19. Cylindrical shockwave-induced compression mechanism in femtosecond laser Bessel pulse micro-drilling of PMMA

    NASA Astrophysics Data System (ADS)

    Wang, Guoyan; Yu, Yanwu; Jiang, Lan; Li, Xiaowei; Xie, Qian; Lu, Yongfeng

    2017-04-01

    Femtosecond (fs) laser Bessel pulses can be employed for high-quality and high-speed fabrication of high-aspect-ratio uniform microhole arrays. This technique exhibits prominent potential in three-dimensional packaging, fluidic devices, fiber sensing, biomedical devices, and aeronautics. However, the fundamental mechanisms remain mysterious. Using the femtosecond time-resolved pump-probe shadowgraph technique, this study revealed that the generation of cylindrical shockwaves inside the bulk material and the corresponding compression mechanism play key roles in the formation of high-aspect-ratio microholes. The phenomena were observed in all experiments of Bessel beam drilling of polymethyl methacrylate. In the aforementioned cases, the compression mechanism was confirmed by measuring sample mass losses that were experimentally determined to be negligible. By contrast, neither cylindrical shockwave nor compression mechanism was observed when a fused silica or Gaussian laser beam was involved.

  20. Liberation From Mechanical Ventilation in Critically Ill Adults: Executive Summary of an Official American College of Chest Physicians/American Thoracic Society Clinical Practice Guideline.

    PubMed

    Schmidt, Gregory A; Girard, Timothy D; Kress, John P; Morris, Peter E; Ouellette, Daniel R; Alhazzani, Waleed; Burns, Suzanne M; Epstein, Scott K; Esteban, Andres; Fan, Eddy; Ferrer, Miguel; Fraser, Gilles L; Gong, Michelle Ng; Hough, Catherine L; Mehta, Sangeeta; Nanchal, Rahul; Patel, Sheena; Pawlik, Amy J; Schweickert, William D; Sessler, Curtis N; Strøm, Thomas; Wilson, Kevin C; Truwit, Jonathon D

    2017-01-01

    This clinical practice guideline addresses six questions related to liberation from mechanical ventilation in critically ill adults. It is the result of a collaborative effort between the American Thoracic Society (ATS) and the American College of Chest Physicians (CHEST). A multidisciplinary panel posed six clinical questions in a population, intervention, comparator, outcomes (PICO) format. A comprehensive literature search and evidence synthesis was performed for each question, which included appraising the quality of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. The Evidence-to-Decision framework was applied to each question, requiring the panel to evaluate and weigh the importance of the problem, confidence in the evidence, certainty about how much the public values the main outcomes, magnitude and balance of desirable and undesirable outcomes, resources and costs associated with the intervention, impact on health disparities, and acceptability and feasibility of the intervention. Evidence-based recommendations were formulated and graded initially by subcommittees and then modified following full panel discussions. The recommendations were confirmed by confidential electronic voting; approval required that at least 80% of the panel members agree with the recommendation. The panel provides recommendations regarding liberation from mechanical ventilation. The details regarding the evidence and rationale for each recommendation are presented in the American Journal of Respiratory and Critical Care Medicine and CHEST. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

  1. Optimization of the dye-sensitized solar cell performance by mechanical compression.

    PubMed

    Meen, Teen Hang; Tsai, Jenn Kai; Tu, Yu Shin; Wu, Tian Chiuan; Hsu, Wen Dung; Chang, Shoou-Jinn

    2014-01-01

    In this study, the P25 titanium dioxide (TiO2) nanoparticle (NP) thin film was coated on the fluorine-doped tin oxide (FTO) glass substrate by a doctor blade method. The film then compressed mechanically to be the photoanode of dye-sensitized solar cells (DSSCs). Various compression pressures on TiO2 NP film were tested to optimize the performance of DSSCs. The mechanical compression reduces TiO2 inter-particle distance improving the electron transport efficiency. The UV-vis spectrophotometer and electrochemical impedance spectroscopy (EIS) were employed to quantify the light-harvesting efficiency and the charge transport impedance at various interfaces in DSSC, respectively. The incident photon-to-current conversion efficiency was also monitored. The results show that when the DSSC fabricated by the TiO2 NP thin film compressed at pressure of 279 kg/cm(2), the minimum resistance of 9.38 Ω at dye/TiO2 NP/electrolyte interfaces, the maximum short-circuit photocurrent density of 15.11 mA/cm(2), and the photoelectric conversion efficiency of 5.94% were observed. Compared to the DSSC fabricated by the non-compression of TiO2 NP thin film, the overall conversion efficiency is improved over 19.5%. The study proves that under suitable compression pressure the performance of DSSC can be optimized.

  2. Optimization of the dye-sensitized solar cell performance by mechanical compression

    PubMed Central

    2014-01-01

    In this study, the P25 titanium dioxide (TiO2) nanoparticle (NP) thin film was coated on the fluorine-doped tin oxide (FTO) glass substrate by a doctor blade method. The film then compressed mechanically to be the photoanode of dye-sensitized solar cells (DSSCs). Various compression pressures on TiO2 NP film were tested to optimize the performance of DSSCs. The mechanical compression reduces TiO2 inter-particle distance improving the electron transport efficiency. The UV–vis spectrophotometer and electrochemical impedance spectroscopy (EIS) were employed to quantify the light-harvesting efficiency and the charge transport impedance at various interfaces in DSSC, respectively. The incident photon-to-current conversion efficiency was also monitored. The results show that when the DSSC fabricated by the TiO2 NP thin film compressed at pressure of 279 kg/cm2, the minimum resistance of 9.38 Ω at dye/TiO2 NP/electrolyte interfaces, the maximum short-circuit photocurrent density of 15.11 mA/cm2, and the photoelectric conversion efficiency of 5.94% were observed. Compared to the DSSC fabricated by the non-compression of TiO2 NP thin film, the overall conversion efficiency is improved over 19.5%. The study proves that under suitable compression pressure the performance of DSSC can be optimized. PMID:25276109

  3. The application of plastic compression to modulate fibrin hydrogel mechanical properties.

    PubMed

    Haugh, Matthew G; Thorpe, Stephen D; Vinardell, Tatiana; Buckley, Conor T; Kelly, Daniel J

    2012-12-01

    The inherent biocompatibility of fibrin hydrogels makes them an attractive material for use in a wide range of tissue engineering applications. Despite this, their relatively low stiffness and high compliance limits their potential for certain orthopaedic applications. Enhanced mechanical properties are desirable so as to withstand surgical handling and in vivo loading after implantation and additionally, can provide important cues to cells seeded within the hydrogel. Standard methods used to enhance the mechanical properties of biological scaffolds such as chemical or thermal crosslinking cannot be used with fibrin hydrogels as cell seeding and gel formation occurs simultaneously. The objective of this study was to investigate the use of plastic compression as a means to improve the mechanical properties of chondrocyte-seeded fibrin hydrogels and to determine the influence of such compression on cell viability within these constructs. It was found that the application of 80% strain to fibrin hydrogels for 30 min (which resulted in a permanent strain of 47.4%) produced a 2.1-fold increase in the subsequent compressive modulus. Additionally, chondrocyte viability was maintained in the plastically compressed gels with significant cellular proliferation and extracellular matrix accumulation observed over 28 days of culture. In conclusion, plastic compression can be used to modulate the density and mechanical properties of cell-seeded fibrin hydrogels and represents a useful tool for both in theatre and in vitro tissue engineering applications.

  4. Compression failure mechanisms of single-ply, unidirectional, carbon-fiber composites

    NASA Technical Reports Server (NTRS)

    Ha, Jong-Bae; Nairn, John A.

    1992-01-01

    A single-ply composite compression test was used to study compression failure mechanisms as a function of fiber type, matrix type, and interfacial strength. Composites made with low- and intermediate-modulus fibers (Hercules AS4 and IM7) in either an epoxy (Hercules 3501-6) or a thermoplastic (ULTEM and LARC-TPI) matrix failed by kink banding and out-of-plane slip. The failures proceeded by rapid and catastrophic damage propagation across the specimen width. Composites made with high-modulus fibers (Hercules HMS4/3501-6) had a much lower compression strength. Their failures were characterized by kink banding and longitudinal splitting. The damage propagated slowly across the specimen width. Composites made with fibers treated to give low interfacial strength had low compression strength. These composites typically failed near the specimen ends and had long kink bands.

  5. Compression failure mechanisms of single-ply, unidirectional, carbon-fiber composites

    NASA Technical Reports Server (NTRS)

    Ha, Jong-Bae; Nairn, John A.

    1992-01-01

    A single-ply composite compression test was used to study compression failure mechanisms as a function of fiber type, matrix type, and interfacial strength. Composites made with low- and intermediate-modulus fibers (Hercules AS4 and IM7) in either an epoxy (Hercules 3501-6) or a thermoplastic (ULTEM and LARC-TPI) matrix failed by kink banding and out-of-plane slip. The failures proceeded by rapid and catastrophic damage propagation across the specimen width. Composites made with high-modulus fibers (Hercules HMS4/3501-6) had a much lower compression strength. Their failures were characterized by kink banding and longitudinal splitting. The damage propagated slowly across the specimen width. Composites made with fibers treated to give low interfacial strength had low compression strength. These composites typically failed near the specimen ends and had long kink bands.

  6. Boron Nitride Coated Carbon Nanotube Arrays with Enhanced Compressive Mechanical Property

    NASA Astrophysics Data System (ADS)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Tan, Dunlin; Zhang, Bowei; Tok, Alfred Iing Yoong; Teo, Edwin Hang Tong

    Vertically aligned carbon nanotube (CNT) array is one of the most promising energy dissipating materials due to its excellent temperature invariant mechanical property. However, the CNT arrays with desirable recoverability after compression is still a challenge. Here, we report on the mechanical enhancement of the CNT arrays reinforced by coating with boron nitride (BN) layers. These BN coated CNT (BN/CNT) arrays exhibit excellent compressive strength and recoverability as compared to those of the as-prepared CNT arrays which totally collapsed after compression. In addition, the BN coating also provides better resistance to oxidation due to its intrinsic thermal stability. This work presented here opens a new pathway towards tuning mechanical behavior of any arbitrary CNT arrays for promising potential such as damper, vibration isolator and shock absorber applications.

  7. Simulated effect on the compressive and shear mechanical properties of bionic integrated honeycomb plates.

    PubMed

    He, Chenglin; Chen, Jinxiang; Wu, Zhishen; Xie, Juan; Zu, Qiao; Lu, Yun

    2015-05-01

    Honeycomb plates can be applied in many fields, including furniture manufacturing, mechanical engineering, civil engineering, transportation and aerospace. In the present study, we discuss the simulated effect on the mechanical properties of bionic integrated honeycomb plates by investigating the compressive and shear failure modes and the mechanical properties of trabeculae reinforced by long or short fibers. The results indicate that the simulated effect represents approximately 80% and 70% of the compressive and shear strengths, respectively. Compared with existing bionic samples, the mass-specific strength was significantly improved. Therefore, this integrated honeycomb technology remains the most effective method for the trial manufacturing of bionic integrated honeycomb plates. The simulated effect of the compressive rigidity is approximately 85%. The short-fiber trabeculae have an advantage over the long-fiber trabeculae in terms of shear rigidity, which provides new evidence for the application of integrated bionic honeycomb plates. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Chest X-Ray

    MedlinePlus

    ... by Image/Video Gallery Your radiologist explains chest x-ray. Transcript Welcome to Radiology Info dot org! Hello, ... you about chest radiography also known as chest x-rays. Chest x-rays are the most commonly performed ...

  9. Microscale Mechanical Deformation Behaviors and Mechanisms in Bulk Metallic Glasses Investigated with Micropillar Compression Experiments

    NASA Astrophysics Data System (ADS)

    Ye, Jianchao

    2011-12-01

    Over the past years of my PhD study, the focused-ion-beam (FIB) based microcompression experiment has been thoroughly investigated with respect to the small-scale deformation in metallic glasses. It was then utilized to explore the elastic and plastic deformation mechanisms in metallic glasses. To this end, micropillars with varying sample sizes and aspect ratios were fabricated by the FIB technique and subsequently compressed on a modified nanoindentation system. An improved formula for the measurement of the Young's modulus was derived by adding a geometrical prefactor to the Sneddon's solution. Through the formula, geometry-independent Young's moduli were extracted from microcompression experiments, which are consistent with nanoindentation results. Furthermore, cyclic microcompression was developed, which revealed reversible inelastic deformation in the apparent elastic regime through high-frequency cyclic loading. The reversible inelastic deformation manifests as hysteric loops in cyclic microcompression and can be captured by the Kelvin-type viscoelastic model. The experimental results indicate that the free-volume zones behave essentially like supercooled liquids with an effective viscosity on the order of 1 x 108 Pas. The microscopic yield strengths were first extracted with a formula derived based on the Mohr-Coulomb law to account for the geometrical effects from the tapered micropillar and the results showed a weak size effect on the yield strengths of a variety of metallic-glass alloys, which can be attributed to Weibull statistics. The nature of the yielding phenomenon was explored with the cyclic micro-compression approach. Through cyclic microcompression of a Zr-based metallic glass, it can be demonstrated that its yielding stress increases at higher applied stress rate but its yielding strain is kept at a constant of ~ 2%. The room-temperature post-yielding deformation behavior of metallic glasses is characterized by flow serrations, which were

  10. Failure mechanisms of uni-ply composite plates with a circular hole under static compressive loading

    NASA Technical Reports Server (NTRS)

    Khamseh, A. R.; Waas, A. M.

    1992-01-01

    The objective of the study was to identify and study the failure mechanisms associated with compressive-loaded uniply graphite/epoxy square plates with a central circular hole. It is found that the type of compressive failure depends on the hole size. For large holes with the diameter/width ratio exceeding 0.062, fiber buckling/kinking initiated at the hole is found to be the dominant failure mechanism. In plates with smaller hole sizes, failure initiates away from the hole edge or complete global failure occurs. Critical buckle wavelengths at failure are presented as a function of the normalized hole diameter.

  11. Failure mechanisms of composite plates with a circular hole under remote biaxial planar compressive loads

    SciTech Connect

    Khamseh, A.R.; Waas, A.M.

    1997-01-01

    The authors report the results of an experimental investigation carried out for the analysis of failure mechanisms in fibrous laminated composite plates containing stress raisers, in the form of circular cutouts, under static biaxial planar compressive loading (i.e., compression in the two inplane orthogonal directions). A series of biaxial tests were carried out with 48 ply graphite/epoxy composites of varying fiber orientation. In all cases, the hole diameter to plate with aspect ratio remained in a range suitable for infinite plate assumptions. Fiber microbuckling, fiber kink banding, and fiber/matrix debonding are identified as the dominant failure mechanisms.

  12. Integrated random-aligned carbon nanotube layers: deformation mechanism under compression

    NASA Astrophysics Data System (ADS)

    Zeng, Zhiping; Gui, Xuchun; Gan, Qiming; Lin, Zhiqiang; Zhu, Yuan; Zhang, Wenhui; Xiang, Rong; Cao, Anyuan; Tang, Zikang

    2014-01-01

    Carbon nanotubes have the potential to construct highly compressible and elastic macroscopic structures such as films, aerogels and sponges. The structure-related deformation mechanism determines the mechanical behavior of those structures and niche applications. Here, we show a novel strategy to integrate aligned and random nanotube layers and reveal their deformation mechanism under uniaxial compression with a large range of strain and cyclic testing. Integrated nanotube layers deform sequentially with different mechanisms due to the distinct morphology of each layer. While the aligned layer forms buckles under compression, nanotubes in the random layer tend to be parallel and form bundles, resulting in the integration of quite different properties (strength and stiffness) and correspondingly distinct plateau regions in the stress-strain curves. Our results indicate a great promise of constructing hierarchical carbon nanotube structures with tailored energy absorption properties, for applications such as cushioning and buffering layers in microelectromechanical systems.Carbon nanotubes have the potential to construct highly compressible and elastic macroscopic structures such as films, aerogels and sponges. The structure-related deformation mechanism determines the mechanical behavior of those structures and niche applications. Here, we show a novel strategy to integrate aligned and random nanotube layers and reveal their deformation mechanism under uniaxial compression with a large range of strain and cyclic testing. Integrated nanotube layers deform sequentially with different mechanisms due to the distinct morphology of each layer. While the aligned layer forms buckles under compression, nanotubes in the random layer tend to be parallel and form bundles, resulting in the integration of quite different properties (strength and stiffness) and correspondingly distinct plateau regions in the stress-strain curves. Our results indicate a great promise of

  13. Inelastic deformation mechanisms in SCS-6/Ti 15-3 MMC lamina under compression

    NASA Technical Reports Server (NTRS)

    Newaz, Golam M.; Majumdar, Bhaskar S.

    1993-01-01

    An investigation was undertaken to study the inelastic deformation mechanisms in (0)(sub 8) and (90)(sub 8) Ti 15-3/SCS-6 lamina subjected to pure compression. Monotonic tests were conducted at room temperature (RT), 538 C and 650 C. Results indicate that mechanical response and deformation characteristics were different in monotonic tension and compression loading whereas some of those differences could be attributed to residual stress effects. There were other differences because of changes in damage and failure modes. The inelastic deformation in the (0)(sub 8) lamina under compression was controlled primarily by matrix plasticity, although some evidence of fiber-matrix debonding was observed. Failure of the specimen in compression was due to fiber buckling in a macroscopic shear zone (the failure plane). The inelastic deformation mechanisms under compression in (90)(sub 8) lamina were controlled by radial fiber fracture, matrix plasticity, and fiber-matrix debonding. The radial fiber fracture was a new damage mode observed for MMC's. Constitutive response was predicted for both the (0)(sub 8) and (90)(sub 8) laminae, using AGLPLY, METCAN, and Battelle's Unit Cell FEA model. Results from the analyses were encouraging.

  14. [Combination of chest physiotherapy and intermittent non-invasive mechanical ventilation for chronic obstructive pulmonary disease patients with respiratory failure].

    PubMed

    Qu, Yunzhong; Peng, Hong; Chen, Ping; Xiang, Xudong

    2009-07-01

    To determine the effect of combination of chest physiotherapy (CPT) and intermittent non-invasive ventilation for chronic obstructive pulmonary disease (COPD) patients with respiratory failure. Ninety COPD patients with intermittent bi-level positive airway pressure (BiPAP) ventilation were randomly divided into 2 groups: control group (n=45) received BiPAP treatment after conventional anti-infection, phlegm treatment and support treatment; CPT group (n=45) received CPT before BiPAP treatment. Clinical symptoms, chest signs,chest X-ray,time of BiPAP therapy, PaO2, and PaCO ) after the treatment were evaluated. Compared with with the control group, patients in the CPT group significantly improved in clinical symptoms, chest signs, chest X-ray absorption as well as shorter BiPAP therapy time, PaO2 increase and PaCO2 decrease(P<0.05).Conclusion For COPD patients who need intermittent non-invasive BiPAP ventilation, receiving CPT can effectively improve the therapeutic effect.CPT and intermittent non invasive BiPAP ventilation cooperate in the treatment of COPD patients with respiratory failure.

  15. Mechanical Criterion for the Rupture of a Cell Membrane under Compression.

    PubMed

    Gonzalez-Rodriguez, David; Guillou, Lionel; Cornat, François; Lafaurie-Janvore, Julie; Babataheri, Avin; de Langre, Emmanuel; Barakat, Abdul I; Husson, Julien

    2016-12-20

    We investigate the mechanical conditions leading to the rupture of the plasma membrane of an endothelial cell subjected to a local, compressive force. Membrane rupture is induced by tilted microindentation, a technique used to perform mechanical measurements on adherent cells. In this technique, the applied force can be deduced from the measured horizontal displacement of a microindenter's tip, as imaged with an inverted microscope and without the need for optical sensors to measure the microindenter's deflection. We show that plasma membrane rupture of endothelial cells occurs at a well-defined value of the applied compressive stress. As a point of reference, we use numerical simulations to estimate the magnitude of the compressive stresses exerted on endothelial cells during the deployment of a stent. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  16. Lower-leg compression, running mechanics, and economy in trained distance runners.

    PubMed

    Stickford, Abigail S; Chapman, Robert F; Johnston, Jeanne D; Stager, Joel M

    2015-01-01

    The efficacy of and mechanisms behind the widespread use of lower-leg compression as an ergogenic aid to improve running performance are unknown. The purpose of this study was to examine whether wearing graduated lower-leg compression sleeves during exercise evokes changes in running economy (RE), perhaps due to altered gait mechanics. Sixteen highly trained male distance runners completed 2 separate RE tests during a single laboratory session, including a randomized-treatment trial of graduated calf-compression sleeves (CS; 15-20 mm Hg) and a control trial (CON) without compression sleeves. RE was determined by measuring oxygen consumption at 3 constant submaximal speeds of 233, 268, and 300 m/min on a treadmill. Running mechanics were measured during the last 30 s of each 4-min stage of the RE test via wireless triaxial 10-g accelerometer devices attached to the top of each shoe. Ground-contact time, swing time, step frequency, and step length were determined from accelerometric output corresponding to foot-strike and toe-off events. Gait variability was calculated as the standard deviation of a given gait variable for an individual during the last 30 s of each stage. There were no differences in VO2 or kinematic variables between CON and CS trials at any of the speeds. Wearing lower-leg compression does not alter the energetics of running at submaximal speeds through changes in running mechanics or other means. However, it appears that the individual response to wearing lower-leg compression varies greatly and warrants further examination.

  17. Subchondral bone microarchitecture and failure mechanism under compression: A finite element study.

    PubMed

    Malekipour, Fatemeh; Oetomo, Denny; Lee, Peter Vee-Sin

    2017-02-21

    Subchondral bone (SCB) microdamage is commonly observed in traumatic joint injuries and has been strongly associated with post-traumatic osteoarthritis (PTOA). Knowledge of the three-dimensional stress and strain distribution within the SCB tissue helps to understand the mechanism of SCB failure, and may lead to an improved understanding of mechanisms of PTOA initiation, prevention and treatment. In this study, we used high-resolution micro-computed tomography (µCT)-based finite element (FE) modelling of cartilage-bone to evaluate the failure mechanism and the locations of SCB tissue at high-risk of initial failure under compression. The µCT images of five cartilage-bone specimens with an average SCB thickness of 1.23±0.20mm were used to develop five µCT-based FE models. The FE models were analysed under axial compressions of approximately 30MPa applied to the cartilage surface while the bone edges were constrained. Strain and stress-based failure criteria were then applied to evaluate the failure mechanism of the SCB tissue under excessive compression through articular cartilage. µCT-based FE models predicted two locations in the SCB at high-risk of initial failure: (1) the interface of the calcified-uncalcified cartilage due to excessive tension, and (2) the trabecular bone beneath the subchondral plate due to excessive compression. µCT-based FE models of cartilage-bone enabled us to quantify the distribution of the applied compression which was transferred through the articular cartilage to its underlying SCB, and to investigate the mechanism and the mode of SCB tissue failure. Ultimately, the results will help to understand the mechanism of injury formation in relation to PTOA.

  18. In vitro mechanical compression induces apoptosis and regulates cytokines release in hypertrophic scars.

    PubMed

    Renò, Filippo; Sabbatini, Maurizio; Lombardi, Francesca; Stella, Maurizio; Pezzuto, Carla; Magliacani, Gilberto; Cannas, Mario

    2003-01-01

    Hypertrophic scars resulting from severe burns are usually treated by continuous elastic compression. Although pressure therapy reaches success rates of 60-85% its mechanisms of action are still poorly understood. In this study, apoptosis induction and release of interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) were evaluated in normal (n = 3) and hypertrophic (=7) scars from burns after in vitro mechanical compression. In the absence of compression (basal condition) apoptotic cells, scored using terminal deoxyribonucleotidyl transferase assay, were present after 24 hours in the derma of both normal scar (23 +/- 0.4% of total cell) and hypertrophic scar (11.3 +/- 1.4%). Mechanical compression (constant pressure of 35 mmHg for 24 hours) increased apoptotic cell percentage both in normal scar (29.5 +/- 0.4%) and hypertrophic scar (29 +/- 1.7%). IL-1beta released in the medium was undetectable in normal scar under basal conditions while in hypertrophic scar the IL-1beta concentration was 3.48 +/- 0.2 ng/g. Compression in hypertrophic scar-induced secretion of IL-1beta twofold higher compared to basal condition. (7.72 +/- 0.2 ng/g). TNF-alpha basal concentration measured in normal scar medium was 8.52 +/- 4.01 ng/g and compression did not altered TNF-alpha release (12.86 +/- 7.84 ng/g). TNF-alpha basal release was significantly higher in hypertrophic scar (14.74 +/- 1.42 ng/g) compared to normal scar samples and TNF-alpha secretion was diminished (3.52 +/- 0.97 ng/g) after compression. In conclusion, in our in vitro model, mechanical compression resembling the clinical use of elastocompression was able to strongly increase apoptosis in the hypertrophic scar derma as observed during granulation tissue regression in normal wound healing. Moreover, the observed modulation of IL-1beta and TNF-alpha release by mechanical loading could play a key role in hypertrophy regression induced by elastocompression.

  19. Thermal and mechanical properties of compression-molded pMDI-reinforced PCL/gluten composites

    USDA-ARS?s Scientific Manuscript database

    Polycaprolactone (PCL) and vital wheat gluten or wheat flour composites were prepared and compatibilized with polymeric diphenylmethane diisocyanate (pMDI) by blending and compression-molding. The thermo-mechanical properties of the composites were determined by thermogravimetric analysis (TGA), di...

  20. A variational principle for compressible fluid mechanics: Discussion of the multi-dimensional theory

    NASA Technical Reports Server (NTRS)

    Prozan, R. J.

    1982-01-01

    The variational principle for compressible fluid mechanics previously introduced is extended to two dimensional flow. The analysis is stable, exactly conservative, adaptable to coarse or fine grids, and very fast. Solutions for two dimensional problems are included. The excellent behavior and results lend further credence to the variational concept and its applicability to the numerical analysis of complex flow fields.

  1. Determining Tension-Compression Nonlinear Mechanical Properties of Articular Cartilage from Indentation Testing.

    PubMed

    Chen, Xingyu; Zhou, Yilu; Wang, Liyun; Santare, Michael H; Wan, Leo Q; Lu, X Lucas

    2016-04-01

    The indentation test is widely used to determine the in situ biomechanical properties of articular cartilage. The mechanical parameters estimated from the test depend on the constitutive model adopted to analyze the data. Similar to most connective tissues, the solid matrix of cartilage displays different mechanical properties under tension and compression, termed tension-compression nonlinearity (TCN). In this study, cartilage was modeled as a porous elastic material with either a conewise linear elastic matrix with cubic symmetry or a solid matrix reinforced by a continuous fiber distribution. Both models are commonly used to describe the TCN of cartilage. The roles of each mechanical property in determining the indentation response of cartilage were identified by finite element simulation. Under constant loading, the equilibrium deformation of cartilage is mainly dependent on the compressive modulus, while the initial transient creep behavior is largely regulated by the tensile stiffness. More importantly, altering the permeability does not change the shape of the indentation creep curves, but introduces a parallel shift along the horizontal direction on a logarithmic time scale. Based on these findings, a highly efficient curve-fitting algorithm was designed, which can uniquely determine the three major mechanical properties of cartilage (compressive modulus, tensile modulus, and permeability) from a single indentation test. The new technique was tested on adult bovine knee cartilage and compared with results from the classic biphasic linear elastic curve-fitting program.

  2. Contact mechanics of the human finger pad under compressive loads.

    PubMed

    Dzidek, Brygida M; Adams, Michael J; Andrews, James W; Zhang, Zhibing; Johnson, Simon A

    2017-02-01

    The coefficient of friction of most solid objects is independent of the applied normal force because of surface roughness. This behaviour is observed for a finger pad except at long contact times (greater than 10 s) against smooth impermeable surfaces such as glass when the coefficient increases with decreasing normal force by about a factor of five for the load range investigated here. This is clearly an advantage for some precision manipulation and grip tasks. Such normal force dependence is characteristic of smooth curved elastic bodies. It has been argued that the occlusion of moisture in the form of sweat plasticises the surface topographical features and their increased compliance allows flattening under an applied normal force, so that the surfaces of the fingerprint ridges are effectively smooth. While the normal force dependence of the friction is consistent with the theory of elastic frictional contacts, the gross deformation behaviour is not and, for commonly reported values of the Young's modulus of stratum corneum, the deformation of the ridges should be negligible compared with the gross deformation of the finger pad even when fully occluded. This paper describes the development of a contact mechanics model that resolves these inconsistencies and is validated against experimental data.

  3. The impact of posture and prolonged cyclic compressive loading on vertebral joint mechanics.

    PubMed

    Gooyers, Chad E; McMillan, Robert D; Howarth, Samuel J; Callaghan, Jack P

    2012-08-01

    An in vitro biomechanics investigation exposing porcine functional spinal units (FSUs) to submaximal cyclic or static compressive forces while in a flexed, neutral, or extended posture. To investigate the combined effect of cyclically applied compressive force (e.g., vibration) and postural deviation on intervertebral joint mechanics. Independently, prolonged vibration exposure and non-neutral postures are known risk factors for development of low back pain and injury. However, there is limited basic scientific evidence to explain how the risk of low back injury from vibration exposure is modified by other mechanical factors. This work examined the influence of static postural deviation on vertebral joint height loss and compressive stiffness under cyclically applied compressive force. Forty-eight FSUs, consisting of 2 adjacent vertebrae, ligaments, and the intervening intervertebral disc were included in the study. Each specimen was randomized to 1 of 3 experimental posture conditions (neutral, flexed, or extended) and assigned to 1 of 2 loading protocols, consisting of (1) cyclic (1500 ± 1200 N applied at 5 Hz using a sinusoidal waveform, resulting in 0.2 g rms acceleration) or (2) 1500 N of static compressive force. RESULTS.: As expected, FSU height loss followed a typical first-order response in both the static and cyclic loading protocols, with the majority (~50%) of the loss occurring in the first 20 minutes of testing. A significant interaction between posture and loading protocol (P < 0.001) was noted in the magnitude of FSU height loss. Subsequent analysis of simple effects revealed significant differences between cyclic and static loading protocols in both a neutral (P = 0.016) and a flexed posture (P < 0.0001). No significant differences (P = 0.320) were noted between pre/postmeasurements of FSU compressive stiffness. Posture is an important mechanical factor to consider when assessing the risk of injury from cyclic loading to the lumbar spine.

  4. Rat disc torsional mechanics: effect of lumbar and caudal levels and axial compression load.

    PubMed

    Espinoza Orías, Alejandro A; Malhotra, Neil R; Elliott, Dawn M

    2009-03-01

    Rat models with altered loading are used to study disc degeneration and mechano-transduction. Given the prominent role of mechanics in disc function and degeneration, it is critical to measure mechanical behavior to evaluate changes after model interventions. Axial compression mechanics of the rat disc are representative of the human disc when normalized by geometry, and differences between the lumbar and caudal disc have been quantified in axial compression. No study has quantified rat disc torsional mechanics. Compare the torsional mechanical behavior of rat lumbar and caudal discs, determine the contribution of combined axial load on torsional mechanics, and compare the torsional properties of rat discs to human lumbar discs. Cadaveric biomechanical study. Cyclic torsion without compressive load followed by cyclic torsion with a fixed compressive load was applied to rat lumbar and caudal disc levels. The apparent torsional modulus was higher in the lumbar region than in the caudal region: 0.081+/-0.026 (MPa/degrees, mean+/-SD) for lumbar axially loaded; 0.066+/-0.028 for caudal axially loaded; 0.091+/-0.033 for lumbar in pure torsion; and 0.056+/-0.035 for caudal in pure torsion. These values were similar to human disc properties reported in the literature ranging from 0.024 to 0.21 MPa/degrees. Use of the caudal disc as a model may be appropriate if the mechanical focus is within the linear region of the loading regime. These results provide support for use of this animal model in basic science studies with respect to torsional mechanics.

  5. Myths and Truths of Nitinol Mechanics: Elasticity and Tension-Compression Asymmetry

    NASA Astrophysics Data System (ADS)

    Bucsek, Ashley N.; Paranjape, Harshad M.; Stebner, Aaron P.

    2016-09-01

    Two prevalent myths of Nitinol mechanics are examined: (1) Martensite is more compliant than austenite; (2) Texture-free Nitinol polycrystals do not exhibit tension-compression asymmetry. By reviewing existing literature, the following truths are revealed: (1) Martensite crystals may be more compliant, equally stiff, or stiffer than austenite crystals, depending on the orientation of the applied load. The Young's Modulus of polycrystalline Nitinol is not a fixed number—it changes with both processing and in operando deformations. Nitinol martensite prefers to behave stiffer under compressive loads and more compliant under tensile loads. (2) Inelastic Nitinol martensite deformation in and of itself is asymmetric, even for texture-free polycrystals. Texture-free Nitinol polycrystals also exhibit tension-compression transformation asymmetry.

  6. Suppression mechanism of Kelvin-Helmholtz instability in compressible fluid flows.

    PubMed

    Karimi, Mona; Girimaji, Sharath S

    2016-04-01

    The transformative influence of compressibility on the Kelvin-Helmholtz instability (KHI) at the interface between two fluid streams of different velocities is explicated. When the velocity difference is small (subsonic), shear effects dominate the interface flow dynamics causing monotonic roll-up of vorticity and mixing between the two streams leading to the KHI. We find that at supersonic speed differentials, compressibility forces the dominance of dilatational (acoustic) rather than shear dynamics at the interface. Within this dilatational interface layer, traveling pressure waves cause the velocity perturbations to become oscillatory. We demonstrate that the oscillatory fluid motion reverses vortex roll-up and segregates the two streams leading to KHI suppression. Analysis and illustrations of the compressibility-induced suppression mechanism are presented.

  7. Compressive mechanical response of graphene foams and their thermal resistance with copper interfaces

    NASA Astrophysics Data System (ADS)

    Park, Wonjun; Li, Xiangyu; Mandal, Nirajan; Ruan, Xiulin; Chen, Yong P.

    2017-03-01

    We report compressive mechanical response of graphene foams (GFs) and the thermal resistance (RTIM) between copper (Cu) and GFs, where GFs were prepared by the chemical vapor deposition method. We observe that Young's modulus (EGF) and compressive strength (σGF) of GFs have a power law dependence on increasing density (ρGF) of GFs. The maximum efficiency of absorbed energy (ηmax) for all GFs during the compression is larger than ˜0.39. We also find that a GF with a higher ρGF shows a larger ηmax. In addition, we observe that the measured RTIM of Cu/GFs at room temperature with a contact pressure of 0.25 MP applied increases from ˜50 to ˜90 mm2 K/W when ρGF increases from 4.7 to 31.9 mg/cm3.

  8. Mechanical Modeling of Foods Including Fracture and Simulation of Food Compression

    NASA Astrophysics Data System (ADS)

    Morimoto, Masamichi; Mizunuma, Hiroshi; Sonomura, Mitsuhiro; Kohyama, Kaoru; Ogoshi, Hiro

    2008-07-01

    The purposes of this research are to simulate the swallowing of foods, and to investigate the relationship between the rheological properties of foods and the swallowing. Here we proposed the mechanical modeling of foods, and simulated the compression test using the finite element method. A linear plasticity model was applied as the rheological model of the foods, and two types of computational elements were used to simulate the fracture behavior. The compression tests with a wedged plunger were simulated for tofu, banana, and biscuit, and were compared with the experimental results. Other than the homogeneous food model, the simulations were conducted for the multi-layer models. Reasonable agreements on the behaviors of compression and fracture were obtained between the simulations and the experiments including the reaction forces on the plunger.

  9. Integrins mediate mechanical compression-induced endothelium-dependent vasodilation through endothelial nitric oxide pathway.

    PubMed

    Lu, Xiao; Kassab, Ghassan S

    2015-09-01

    Cardiac and skeletal muscle contraction lead to compression of intramuscular arterioles, which, in turn, leads to their vasodilation (a process that may enhance blood flow during muscle activity). Although endothelium-derived nitric oxide (NO) has been implicated in compression-induced vasodilation, the mechanism whereby arterial compression elicits NO production is unclear. We cannulated isolated swine (n = 39) myocardial (n = 69) and skeletal muscle (n = 60) arteriole segments and exposed them to cyclic transmural pressure generated by either intraluminal or extraluminal pressure pulses to simulate compression in contracting muscle. We found that the vasodilation elicited by internal or external pressure pulses was equivalent; moreover, vasodilation in response to pressure depended on changes in arteriole diameter. Agonist-induced endothelium-dependent and -independent vasodilation was used to verify endothelial and vascular smooth muscle cell viability. Vasodilation in response to cyclic changes in transmural pressure was smaller than that elicited by pharmacological activation of the NO signaling pathway. It was attenuated by inhibition of NO synthase and by mechanical removal of the endothelium. Stemming from previous observations that endothelial integrin is implicated in vasodilation in response to shear stress, we found that function-blocking integrin α5β1 or αvβ3 antibodies attenuated cyclic compression-induced vasodilation and NOx (NO(-)2 and NO(-)3) production, as did an RGD peptide that competitively inhibits ligand binding to some integrins. We therefore conclude that integrin plays a role in cyclic compression-induced endothelial NO production and thereby in the vasodilation of small arteries during cyclic transmural pressure loading. © 2015 Lu and Kassab.

  10. Comparative assessment of intrinsic mechanical stimuli on knee cartilage and compressed agarose constructs.

    PubMed

    Completo, A; Bandeiras, C; Fonseca, F

    2017-06-01

    A well-established cue for improving the properties of tissue-engineered cartilage is mechanical stimulation. However, the explicit ranges of mechanical stimuli that correspond to favorable metabolic outcomes are elusive. Usually, these outcomes have only been associated with the applied strain and frequency, an oversimplification that can hide the fundamental relationship between the intrinsic mechanical stimuli and the metabolic outcomes. This highlights two important key issues: the firstly is related to the evaluation of the intrinsic mechanical stimuli of native cartilage; the second, assuming that the intrinsic mechanical stimuli will be important, deals with the ability to replicate them on the tissue-engineered constructs. This study quantifies and compares the volume of cartilage and agarose subjected to a given magnitude range of each intrinsic mechanical stimulus, through a numerical simulation of a patient-specific knee model coupled with experimental data of contact during the stance phase of gait, and agarose constructs under direct-dynamic compression. The results suggest that direct compression loading needs to be parameterized with time-dependence during the initial culture period in order to better reproduce each one of the intrinsic mechanical stimuli developed in the patient-specific cartilage. A loading regime which combines time periods of low compressive strain (5%) and frequency (0.5Hz), in order to approach the maximal principal strain and fluid velocity stimulus of the patient-specific cartilage, with time periods of high compressive strain (20%) and frequency (3Hz), in order to approach the pore pressure values, may be advantageous relatively to a single loading regime throughout the full culture period. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  11. Research of mechanics of the compact bone microvolume and porous ceramics under uniaxial compression

    SciTech Connect

    Kolmakova, T. V. Buyakova, S. P. Kul’kov, S. N.

    2015-11-17

    The research results of the mechanics are presented and the effective mechanical characteristics under uniaxial compression of the simulative microvolume of the compact bone are defined subject to the direction of the collagen-mineral fibers, porosity and mineral content. The experimental studies of the mechanics are performed and the effective mechanical characteristics of the produced porous zirconium oxide ceramics are defined. The recommendations are developed on the selection of the ceramic samples designed to replace the fragment of the compact bone of a definite structure and mineral content.

  12. Researches of mechanical behaviour of the bone micro volumes and porous ceramics under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Kolmakova, T. V.; Buyakova, S. P.; Kulkov, S. N.

    2017-02-01

    The research results of the mechanics are presented and the effective mechanical characteristics under uniaxial compression of the simulative micro volume of the compact bone are defined subject to the direction of the collagen-mineral fibers, porosity and mineral content. The experimental and computer studies of the mechanics are performed and the effective mechanical characteristics of the porous zirconium oxide ceramics are defined. The recommendations are developed on the selection of the ceramic samples designed to replace the fragment of the compact bone of a definite structure and mineral content.

  13. Acute forces required for fatal compression asphyxia: A biomechanical model and historical comparisons.

    PubMed

    Kroll, Mark W; Still, G Keith; Neuman, Tom S; Graham, Michael A; Griffin, Lanny V

    2017-01-01

    Background Fatalities from acute compression have been reported with soft-drink vending machine tipping, motor vehicle accidents, and trench cave-ins. A major mechanism of such deaths is flail chest but the amount of force required is unclear. Between the range of a safe static chest compression force of 1000 N (102 kg with earth gravity) and a lethal dynamic force of 10-20 kN (falling 450 kg vending machines), there are limited quantitative human data on the force required to cause flail chest, which is a major correlate of acute fatal compression asphyxia. Methods We modeled flail chest as bilateral fractures of six adjacent ribs. The static and dynamic forces required to cause such a ribcage failure were estimated using a biomechanical model of the thorax. The results were then compared with published historical records of judicial "pressing," vending machine fatalities, and automobile safety cadaver testing. Results and conclusion The modeling results suggest that an adult male requires 2550 ± 250 N of chest-applied distributed static force (260 ± 26 kg with earth gravity) or 4050 ± 320 N of dynamic force to cause flail chest from short-term chest compression.

  14. Compression failure mechanisms of uni-ply composite plates with a circular cutout

    NASA Technical Reports Server (NTRS)

    Khamseh, A. R.; Waas, A. M.

    1992-01-01

    The effect of circular-hole size on the failure mode of uniply graphite-epoxy composite plates is investigated experimentally and analytically for uniaxial compressive loading. The test specimens are sandwiched between polyetherimide plastic for nondestructive evaluations of the uniply failure mechanisms associated with a range of hole sizes. Finite-element modeling based on classical lamination theory is conducted for the corresponding materials and geometries to reproduce the experimental results analytically. The type of compressive failure is found to be a function of hole size, with fiber buckling/kinking at the hole being the dominant failure mechanism for hole diam/plate width ratios exceeding 0.062. The results of the finite-element analysis supported the experimental data for these failure mechanisms and for those corresponding to smaller hole sizes.

  15. The role of the thoracic compression reflex in the Heimlich Maneuver.

    PubMed

    Crawford, L M; Emmett, J W

    1977-01-01

    Using the dog as an experimental model, the relationship of the Thoracic Compression Reflex (TCR) to the Heimlich Maneuver (HM) was examined. TCR was equally effective as lateral chest compression in relieving artificially induced choke. Destruction of the TCR by vagotomy rendered relief of choke by HM ineffectual in 5 of 8 dogs. It was concluded TCR may be a factor in HM, but that mechanical compression of the lungs is also involved.

  16. Coaxial carbon@boron nitride nanotube arrays with enhanced thermal stability and compressive mechanical properties

    NASA Astrophysics Data System (ADS)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Huang, Jingfeng; Tan, Dunlin; Zhang, Bowei; Teo, Edwin Hang Tong; Tok, Alfred Iing Yoong

    2016-05-01

    Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability. CNT arrays are grown using a commercially available thermal chemical vapor deposition (TCVD) technique and an outer BNNT with a wall thickness up to 1.37 nm is introduced by a post-growth TCVD treatment. Importantly, compared to the as-grown CNT arrays which deform almost plastically upon compression, the coaxial C@BNNT arrays exhibit an impressive ~4-fold increase in compressive strength with nearly full recovery after the first compression cycle at a 50% strain (76% recovery maintained after 10 cycles), as well as a significantly high and persistent energy dissipation ratio (~60% at a 50% strain after 100 cycles), attributed to the synergistic effect between the CNT and outer BNNT. Additionally, the as-prepared C@BNNT arrays show an improved structural stability in air at elevated temperatures, attributing to the outstanding thermal stability of the outer BNNT. This work provides new insights into tailoring the mechanical and thermal behaviours of arbitrary CNT arrays which enables a broader range of applications.Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability

  17. On the Study of Lifting Mechanism of a Soft Porous Media under Fast Compression

    NASA Astrophysics Data System (ADS)

    Wu, Qianhong; Santhanam, S.; Nathan, R.; Vucbmss Team

    2015-11-01

    Fluid flow in a soft porous media under fast compressions is widely observed in biological systems and industrial applications. Despite of much progress, it remains unclear for the lifting mechanisms of the porous media due to the lack of complete experimental verifications of theoretical models. We report herein a unique approach to treat the limitation. The permeability of a synthetic fibrous porous media as a function of its compression was first measured. The material was then employed in a dynamic compression experiment using a porous-walled cylinder piston apparatus. The obtained transient compression of the porous media and the aforementioned permeability data were applied in different theoretical models for the pore pressure generation, which conclusively proved the validity of the consolidation theory developed by Wu et al. (JFM, 542, 281, 2005). Furthermore, the solid phase lifting force was separated from the total reaction force and was characterized by a new viscoelastic model, containing a nonlinear spring in conjunction with a linear viscoelastic Generalized Maxwell mechanical module. Excellent agreement was obtained between the experiment and the theory. Thus, the lifting forces from both the fluid and the solid were determined. This project is supported by NSF Grant 1511096.

  18. Expiratory rib cage compression in mechanically ventilated adults: systematic review with meta-analysis

    PubMed Central

    Borges, Lúcia Faria; Saraiva, Mateus Sasso; Saraiva, Marcos Ariel Sasso; Macagnan, Fabrício Edler; Kessler, Adriana

    2017-01-01

    Objective To review the literature on the effects of expiratory rib cage compression on ventilatory mechanics, airway clearance, and oxygen and hemodynamic indices in mechanically ventilated adults. Methods Systematic review with meta-analysis of randomized clinical trials in the databases MEDLINE (via PubMed), EMBASE, Cochrane CENTRAL, PEDro, and LILACS. Studies on adult patients hospitalized in intensive care units and under mechanical ventilation that analyzed the effects of expiratory rib cage compression with respect to a control group (without expiratory rib cage compression) and evaluated the outcomes static and dynamic compliance, sputum volume, systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, peripheral oxygen saturation, and ratio of arterial oxygen partial pressure to fraction of inspired oxygen were included. Experimental studies with animals and those with incomplete data were excluded. Results The search strategy produced 5,816 studies, of which only three randomized crossover trials were included, totaling 93 patients. With respect to the outcome of heart rate, values were reduced in the expiratory rib cage compression group compared with the control group [-2.81 bpm (95% confidence interval [95%CI]: -4.73 to 0.89; I2: 0%)]. Regarding dynamic compliance, there was no significant difference between groups [-0.58mL/cmH2O (95%CI: -2.98 to 1.82; I2: 1%)]. Regarding the variables systolic blood pressure and diastolic blood pressure, significant differences were found after descriptive evaluation. However, there was no difference between groups regarding the variables secretion volume, static compliance, ratio of arterial oxygen partial pressure to fraction of inspired oxygen, and peripheral oxygen saturation. Conclusion There is a lack of evidence to support the use of expiratory rib cage compression in routine care, given that the literature on this topic offers low methodological quality and is inconclusive. PMID

  19. Endoplasmic reticulum stress regulates rat mandibular cartilage thinning under compressive mechanical stress.

    PubMed

    Li, Huang; Zhang, Xiang-Yu; Wu, Tuo-Jiang; Cheng, Wei; Liu, Xin; Jiang, Ting-Ting; Wen, Juan; Li, Jie; Ma, Qiao-Ling; Hua, Zi-Chun

    2013-06-21

    Compressive mechanical stress-induced cartilage thinning has been characterized as a key step in the progression of temporomandibular joint diseases, such as osteoarthritis. However, the regulatory mechanisms underlying this loss have not been thoroughly studied. Here, we used an established animal model for loading compressive mechanical stress to induce cartilage thinning in vivo. The mechanically stressed mandibular chondrocytes were then isolated to screen potential candidates using a proteomics approach. A total of 28 proteins were identified that were directly or indirectly associated with endoplasmic reticulum stress, including protein disulfide-isomerase, calreticulin, translationally controlled tumor protein, and peptidyl-prolyl cis/trans-isomerase protein. The altered expression of these candidates was validated at both the mRNA and protein levels. The induction of endoplasmic reticulum stress by mechanical stress loading was confirmed by the activation of endoplasmic reticulum stress markers, the elevation of the cytoplasmic Ca(2+) level, and the expansion of endoplasmic reticulum membranes. More importantly, the use of a selective inhibitor to block endoplasmic reticulum stress in vivo reduced the apoptosis observed at the early stages of mechanical stress loading and inhibited the proliferation observed at the later stages of mechanical stress loading. Accordingly, the use of the inhibitor significantly restored cartilage thinning. Taken together, these results demonstrated that endoplasmic reticulum stress is significantly activated in mechanical stress-induced mandibular cartilage thinning and, more importantly, that endoplasmic reticulum stress inhibition alleviates this loss, suggesting a novel pharmaceutical strategy for the treatment of mechanical stress-induced temporomandibular joint diseases.

  20. Chest tube insertion

    MedlinePlus

    Chest drainage tube insertion; Insertion of tube into chest; Tube thoracostomy; Pericardial drain ... When your chest tube is inserted, you will lie on your side or sit partly upright, with one arm over your head. Sometimes, ...

  1. Chest X Ray?

    MedlinePlus

    ... this page from the NHLBI on Twitter. Chest X Ray A chest x ray is a fast and painless imaging test that ... tissue scarring, called fibrosis. Doctors may use chest x rays to see how well certain treatments are working ...

  2. Mechanical properties in crumple-formed paper derived materials subjected to compression.

    PubMed

    Hanaor, D A H; Flores Johnson, E A; Wang, S; Quach, S; Dela-Torre, K N; Gan, Y; Shen, L

    2017-06-01

    The crumpling of precursor materials to form dense three dimensional geometries offers an attractive route towards the utilisation of minor-value waste materials. Crumple-forming results in a mesostructured system in which mechanical properties of the material are governed by complex cross-scale deformation mechanisms. Here we investigate the physical and mechanical properties of dense compacted structures fabricated by the confined uniaxial compression of a cellulose tissue to yield crumpled mesostructuring. A total of 25 specimens of various densities were tested under compression. Crumple formed specimens exhibited densities in the range 0.8-1.3 g cm(-3), and showed high strength to weight characteristics, achieving ultimate compressive strength values of up to 200 MPa under both quasi-static and high strain rate loading conditions and deformation energy that compares well to engineering materials of similar density. The materials fabricated in this work and their mechanical attributes demonstrate the potential of crumple-forming approaches in the fabrication of novel energy-absorbing materials from low-cost precursors such as recycled paper. Stiffness and toughness of the materials exhibit density dependence suggesting this forming technique further allows controllable impact energy dissipation rates in dynamic applications.

  3. Investigating compression failure mechanisms in composite laminates with a transient fiberglass-epoxy birefringent material

    NASA Technical Reports Server (NTRS)

    Shuart, M. J.; Williams, J. G.

    1984-01-01

    An experimental study is reported in which a nondestructive technique involving the use of a transparent fiberglass-epoxy composite birefringent material has been used to investigate compression failure mechanisms in graphite-epoxy laminates. It is shown that the birefringency and transparency of the fiberglass-epoxy material permits regions of high stress to be located and the mechanisms of local failure propagation to be identified within the laminate. The material may also be useful for studying stress fields and for identifying failure initiation and propagation mechanisms in a wide variety of composite-structure problems.

  4. Mechanical response of 3D Insert(®) PCL to compression.

    PubMed

    Brunelli, M; Perrault, C M; Lacroix, D

    2017-01-01

    3D polymeric scaffolds are increasingly used for in vitro experiments aiming to mimic the environment found in vivo, to support for cellular growth and to induce differentiation through the application of external mechanical cues. In research, experimental results must be shown to be reproducible to be claimed as valid and the first clause to ensure consistency is to provide identical initial experimental conditions between trials. As a matter of fact, 3D structures fabricated in batch are supposed to present a highly reproducible geometry and consequently, to give the same bulk response to mechanical forces. This study aims to measure the overall mechanical response to compression of commercially available 3D Insert PCL scaffolds (3D PCL) fabricated in series by fuse deposition and evaluate how small changes in the architecture of scaffolds affect the mechanical response. The apparent elastic modulus (Ea) was evaluated by performing quasi-static mechanical tests at various temperatures showing a decrease in material stiffness from 5MPa at 25°C to 2.2MPa at 37°C. Then, a variability analysis revealed variations in Ea related to the repositioning of the sample into the testing machine, but also consistent differences comparing different scaffolds. To clarify the source of the differences measured in the mechanical response, the same scaffolds previously undergoing compression, were scanned by micro computed tomography (μCT) to identify any architectural difference. Eventually, to clarify the contribution given by differences in the architecture to the standard deviation of Ea, their mechanical response was qualitatively compared to a compact reference material such as polydimethylsiloxane (PDMS). This study links the geometry, architecture and mechanical response to compression of 3D PCL scaffolds and shows the importance of controlling such parameters in the manufacturing process to obtain scaffolds that can be used in vitro or in vivo under reproducible

  5. Chest physiotherapy on the respiratory mechanics and elimination of sputum in paralyzed and mechanically ventilated patients with acute lung injury: a pilot study.

    PubMed

    Suh, Minhee; Heitkemper, Margaret; Smi, Choi-Kwon

    2011-03-01

    Chest physiotherapy (CPT) is commonly used for mechanically ventilated patients, but little is known about its physiological effects, particularly in patients with acute lung injury (ALI). The aim of the study was to determine the benefits and risks of delivering multimodal respiratory physiotherapy to mechanically ventilated patients with ALI receiving paralytic agents. A repeated measure-experimental design using a counterbalancing method was employed. Fifteen patients received CPT (vibration, percussion, or palm-cup percussion) in addition to the routine CPT in a randomized order. Another 15 patients, contraindicated for the percussion technique, received routine CPT including manual hyperinflation and position change, and were observed as a comparative group. The effects of CPT were evaluated by measuring the volume of aspirated secretions and the dynamic lung compliance (Cd) over time. For the adverse effects, peripheral oxygen saturation (SpO2) was recorded. Cd and SpO2 were recorded at the baseline period, immediately after the physiotherapy treatment, and at 10, 20, 30 and 60 minutes posttreatment. The volume of collected secretions did not differ significantly when compared between the groups (p = .838). Cd increased significantly over time in the manual percussion (p = .042) and palm-cup percussion (p = .046) group, where Cd in the latter remained elevated twice longer than in the former. None of the CPT techniques exerted major detrimental effects on SpO2. We found that the palm-cup percussion technique was the most effective in increasing Cd without any accompanying detrimental effects on SpO2. However, additional CPT did not affect the volume of aspirated secretions. Copyright © 2011 Korean Society of Nursing Science. Published by Elsevier B.V. All rights reserved.

  6. Failure mechanisms in laminated carbon/carbon composites under biaxial compression

    SciTech Connect

    Grape, J.A.; Gupta, V.

    1995-07-01

    The failure mechanisms of 2D carbon/carbon (C/C) woven laminates have been determined under inplane biaxial compression loads, and the associated failure envelopes that account for the effect of matrix-type and loading directions were also obtained. The failure was in the form of micro-kinking of fiber bundles, interspersed with localized interply delaminations to form an overall shear fault. The shear fault was aligned with the major axis of loading except at above 75% of balanced biaxial compressive stress where failure occurred along both axes. Although the biaxial strength varied significantly with the ratio of in-plane principal stresses, R, there was no variation in the local failure mechanisms. Accordingly, it was found that the samples fail upon achieving a critical strain along the primary axis of loading.

  7. Constitutive model for municipal solid waste incorporating mechanical creep and biodegradation-induced compression.

    PubMed

    Sivakumar Babu, G L; Reddy, Krishna R; Chouksey, Sandeep K

    2010-01-01

    A constitutive model is proposed to describe the stress-strain behavior of municipal solid waste (MSW) under loading using the critical state soil mechanics framework. The modified cam clay model is extended to incorporate the effects of mechanical creep and time dependent biodegradation to calculate total compression under loading. Model parameters are evaluated based on one-dimensional compression and triaxial consolidated undrained test series conducted on three types of MSW: (a) fresh MSW obtained from working phase of a landfill, (b) landfilled waste retrieved from a landfill after 1.5 years of degradation, and (c) synthetic MSW with controlled composition. The model captures the stress-strain and pore water pressure response of these three types of MSW adequately. The model is useful for assessing the deformation and stability of landfills and any post-closure development structures located on landfills.

  8. Chest Injuries and Disorders

    MedlinePlus

    ... inside of the chest cavity. Chest injuries and disorders include Heart diseases Lung diseases and collapsed lung Pleural disorders Esophagus disorders Broken ribs Thoracic aortic aneurysms Disorders ...

  9. CT angiography - chest

    MedlinePlus

    Computed tomography angiography - thorax; CTA - lungs; Pulmonary embolism - CTA chest; Thoracic aortic aneurysm - CTA chest; Venous thromboembolism - CTA lung; Blood clot - CTA lung; Embolus - CTA lung; CT ...

  10. Barrier Compression and Its Contribution to Both Classical and Quantum Mechanical Aspects of Enzyme Catalysis

    PubMed Central

    Hay, Sam; Johannissen, Linus O.; Sutcliffe, Michael J.; Scrutton, Nigel S.

    2010-01-01

    Abstract It is generally accepted that enzymes catalyze reactions by lowering the apparent activation energy by transition state stabilization or through destabilization of ground states. A more controversial proposal is that enzymes can also accelerate reactions through barrier compression—an idea that has emerged from studies of H-tunneling reactions in enzyme systems. The effects of barrier compression on classical (over-the-barrier) reactions, and the partitioning between tunneling and classical reaction paths, have largely been ignored. We performed theoretical and computational studies on the effects of barrier compression on the shape of potential energy surfaces/reaction barriers for model (malonaldehyde and methane/methyl radical anion) and enzymatic (aromatic amine dehydrogenase) proton transfer systems. In all cases, we find that barrier compression is associated with an approximately linear decrease in the activation energy. For partially nonadiabatic proton transfers, we show that barrier compression enhances, to similar extents, the rate of classical and proton tunneling reactions. Our analysis suggests that barrier compression—through fast promoting vibrations, or other means—could be a general mechanism for enhancing the rate of not only tunneling, but also classical, proton transfers in enzyme catalysis. PMID:20085724

  11. Introduction of Enhanced Compressive Residual Stress Profiles in Aerospace Components Using Combined Mechanical Surface Treatments

    NASA Astrophysics Data System (ADS)

    Gopinath, Abhay; Lim, Andre; Nagarajan, Balasubramanian; Cher Wong, Chow; Maiti, Rajarshi; Castagne, Sylvie

    2016-11-01

    Mechanical surface treatments such as Shot Peening (SP) and Deep Cold Rolling (DCR) are being used to introduce Compressive Residual Stress (CRS) at the surface and subsurface layers of aerospace components, respectively. This paper investigates the feasibility of a combined introduction of both the surface and sub-surface compressive residual stress on Ti6Al4V material through a successive application of the two aforementioned processes, one after the other. CRS profiles between individual processes were compared to that of combination of processes to validate the feasibility. It was found out that shot peening introduces surface compressive residual stress into the already deep cold rolled sample, resulting in both surface and sub-surface compressive residual stresses in the material. However the drawback of such a combination would be the increased surface roughness after shot peening a deep cold rolled sample which can be critical especially in compressor components. Hence, a new technology, Vibro-Peening (VP) may be used as an alternative to SP to introduce surface stress at reduced roughness.

  12. Mechanical response of common millet (Panicum miliaceum) seeds under quasi-static compression: Experiments and modeling.

    PubMed

    Hasseldine, Benjamin P J; Gao, Chao; Collins, Joseph M; Jung, Hyun-Do; Jang, Tae-Sik; Song, Juha; Li, Yaning

    2017-01-06

    The common millet (Panicum miliaceum) seedcoat has a fascinating complex microstructure, with jigsaw puzzle-like epidermis cells articulated via wavy intercellular sutures to form a compact layer to protect the kernel inside. However, little research has been conducted on linking the microstructure details with the overall mechanical response of this interesting biological composite. To this end, an integrated experimental-numerical-analytical investigation was conducted to both characterize the microstructure and ascertain the microscale mechanical properties and to test the overall response of kernels and full seeds under macroscale quasi-static compression. Scanning electron microscopy (SEM) was utilized to examine the microstructure of the outer seedcoat and nanoindentation was performed to obtain the material properties of the seedcoat hard phase material. A multiscale computational strategy was applied to link the microstructure to the macroscale response of the seed. First, the effective anisotropic mechanical properties of the seedcoat were obtained from finite element (FE) simulations of a microscale representative volume element (RVE), which were further verified from sophisticated analytical models. Then, macroscale FE models of the individual kernel and full seed were developed. Good agreement between the compression experiments and FE simulations were obtained for both the kernel and the full seed. The results revealed the anisotropic property and the protective function of the seedcoat, and showed that the sutures of the seedcoat play an important role in transmitting and distributing loads in responding to external compression.

  13. Effects of cement augmentation on the mechanical stability of multilevel spine after vertebral compression fracture

    PubMed Central

    Wang, Tian; Pelletier, Matthew H.; Walsh, William R.

    2016-01-01

    Background Studies on the effects of cement augmentation or vertebroplasty on multi-level spine after vertebral compression fractures are lacking. This paper seeks to establish a 3-vertebrae ovine model to determine the impact of compression fracture on spine biomechanics, and to discover if cement augmentation can restore mechanical stability to fractured spine. Methods Five lumbar spine segments (L1-L3) were obtained from 5-year-old female Merino sheep. Standardized wedge-compression fractures were generated in each L2 vertebra, and then augmented with polymethyl methacrylate (PMMA) cement mixed with 30% barium sulphate powder. Biomechanical pure moment testing in axial rotation (AR), flexion/extension (FE) and lateral bending (LB) was carried out in the intact, fractured and repaired states. Range of motion (ROM) and neutral zone (NZ) parameters were compared, and plain radiographs taken at every stage. Results Except for a significant increase in ROM between the intact and fractured states in AR between L1 and L2 (P<0.05), there were no other significant differences in ROM or NZ between the other groups. There was a trend towards an increase in ROM and NZ in all directions after fracture, but this did not reach significance. Normal biomechanics was only minimally restored after augmentation. Conclusions Results suggest that cement augmentation could not restore mechanical stability of fractured spine. Model-specific factors may have had a role in these findings. Caution should be exercised when applying these results to humans. PMID:27683707

  14. Chest wall reconstruction after extended resection

    PubMed Central

    Seder, Christopher W.

    2016-01-01

    Extensive chest wall resection and reconstruction is a challenging procedure that requires a multidisciplinary approach, including input from thoracic surgeons, plastic surgeons, neurosurgeons, and radiation oncologists. The primary goals of any chest wall reconstruction is to obliterate dead space, restore chest wall rigidity, preserve pulmonary mechanics, protect intrathoracic organs, provide soft tissue coverage, minimize deformity, and allow patients to receive adjuvant radiotherapy. Successful chest wall reconstruction requires the re-establishment of skeletal stability to prevent chest wall hernias, avoids thoracoplasty-like contraction of the operated side, protects underlying viscera, and maintain a cosmetically-acceptable appearance. After skeletal stability is established, full tissue coverage can be achieved using direct closure, skin grafts, local advancement flaps, pedicled myocutaneous flaps, or free flaps. This review examines the indications for chest wall reconstruction and describes techniques for establishment of chest wall rigidity and soft tissue coverage. PMID:27942408

  15. Deformation and failure mechanisms of 18650 battery cells under axial compression

    NASA Astrophysics Data System (ADS)

    Zhu, Juner; Zhang, Xiaowei; Sahraei, Elham; Wierzbicki, Tomasz

    2016-12-01

    An important deformation mode during ground impacts of battery packs made of cylindrical battery cells is axial compression. This type of loading subjects the cell to a complex deformation pattern and failure mechanism. The design of endcaps plays an important role in such deformations. To explore the sequence of deformation and the underlying failure mechanisms, a combined experimental/numerical study was carried out. Tests were conducted on 18650 cells, and the deformation of each component was carefully investigated and documented. There are four different stages in the force-displacement curve, corresponding with deformation of various components in the endcap assembly. A short circuit happens at a displacement of 4 mm. To clarify these observations, a detailed Finite Element model was set up, covering the geometry and the mechanical property of almost all the components of the cell. Using the simulation results, the sequence of the axial compression was revealed, which was subsequently validated by Micro CT scans as well as analytical solutions. Based on the precise analysis of the mechanical behavior, the cause of the short circuit during axial loading was clarified. Two failure mechanisms in the separator at the top section of the cell explain the possible causes of short circuit.

  16. Establishing the Foundations of the Mechanics of Fracture of Materials Compressed Along Cracks (Review)

    NASA Astrophysics Data System (ADS)

    Guz, A. N.

    2014-01-01

    The basic results of establishing the foundations of the mechanics of fracture of homogeneous materials compressed along cracks and inhomogeneous (composite) materials compressed along interface cracks are analyzed. These results were obtained using elastic, plastic, and viscoelastic material models. This review consists of three parts. The first part discusses the basic concept that the start (onset) of fracture is the mechanism of local instability near the cracks located in a single plane or parallel planes. The fracture criterion and the basic problems arising in this division of fracture mechanics are also formulated. Two basic approaches to establishing the foundations of the mechanics of fracture of materials compressed along cracks are outlined. One approach, so-called beam approximation, is based on various applied theories of stability of thin-walled systems (including the Bernoulli, Kirchhoff-Love, Timoshenko-type hypotheses, etc.). This approach is essentially approximate and introduces an irreducible error into the calculated stresses. The other approach is based on the basic equations and methods of the three-dimensional linearized theory of stability of deformable bodies for finite and small subcritical strains. This approach does not introduce major errors typical for the former approach and allows obtaining results with accuracy acceptable for mechanics. The second part offers a brief analysis of the basic results obtained with the first approach and a more detailed analysis of the basic results obtained with the second approach, including the consideration of the exact solutions for interacting cracks in a single plane and in parallel planes and results for some structural materials. The third part reports new results for interacting cracks in very closely spaced (or coinciding, as an asymptotic case) planes. These results may be considered a transition from the second approach (three-dimensional linearized theory of elastic stability) to the

  17. A mechanism responsible for reducing compression strength of through-the-thickness reinforced composite material

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    1992-01-01

    A study was conducted to identify one of the mechanisms that contributes to the reduced compression strength of composite materials with through-the-thickness (TTT) reinforcements. In this study a series of thick (0/90) laminates with stitched and integrally woven TTT reinforcements were fabricated and statically tested. In both the stitching and weaving process a surface loop of TTT reinforcement yarn is created between successive TTT penetrations. It was shown that the surface loop of the TTT reinforcement 'kinked' the in-plane fibers in such a manner that they were made ineffective in carrying compressive load. The improvement in strength by removal of the surface loop and 'kinked' in-plane fibers was between 7 and 35 percent.

  18. High-frequency oscillation of the airway and chest wall.

    PubMed

    Fink, James B; Mahlmeister, Michael J

    2002-07-01

    High-frequency oscillation (HFO), applied to either the airway or chest wall, has been associated with changes in sputum attributes and clearance. The evolution of evidence, both in vitro and in vivo, supporting the use of HFO is reviewed. Devices that apply HFO to the airway range from the relatively simple mechanical Flutter and Acapella devices to the more complex Percussionaire Intrapercussive Ventilators. and the Hayek Oscillator are designed to provide high-frequency chest wall compression. Operation and use of these devices are described with examples of differentiation of device types by characterization of flows, and airway and esophageal pressures. Although HFO devices span a broad range of costs, they provide a reasonable therapeutic option to support secretion clearance for patients with cystic fibrosis.

  19. Augmentation improves human cadaveric vertebral body compression mechanics for lumbar total disc replacement.

    PubMed

    Yoder, Jonathon H; Auerbach, Joshua D; Maurer, Philip M; Erbe, Erik M; Entrekin, Dean; Balderston, Richard A; Bertagnoli, Rudolf; Elliott, Dawn M

    2010-04-20

    Cadaveric biomechanical study. To quantify the effects of vertebral body augmentation on biomechanics under axial compression by a total disc replacement (TDR) implant. TDR is a surgical alternative to lumbar spinal fusion to treat degenerative disc disease. Osteoporosis in the adjacent vertebrae to the interposed TDR may lead to implant subsidence or vertebral body fracture. Vertebral augmentation is used to treat osteoporotic compression fracture. This study sought to evaluate whether vertebral augmentation improves biomechanics under TDR axial loading. Forty-five L1-L5 lumbar vertebral body segments with intact posterior elements were used. Peripheral quantitative computed tomography scans were performed to determine bone density, and specimens were block-randomized by bone density into augmentation and control groups. A semiconstrained keeled lumbar disc replacement device was implanted, providing 50% endplate coverage. Vertebral augmentation of 17.6% +/- 0.9% vertebral volume fill with Cortoss was performed on the augmentation group. All segments underwent axial compression at a rate of 0.2 mm/s to 6 mm. The load-displacement response for all specimens was nonlinear. Subfailure mechanical properties with augmentation were significantly different from control; in all cases, the augmented group was 2 times higher than control. At failure, the maximum load and stiffness with augmentation was not significantly different from control. The maximum apparent stress and modulus with augmentation were 2 times and 1.3 times greater than control, respectively. The subfailure stress and apparent modulus with augmentation were moderately correlated with bone density whereas the control subfailure properties were not. The augmented maximum stress was not correlated with bone density, whereas the control was weakly correlated. The maximum apparent modulus was moderately correlated with bone density for both the augmented and the control groups. Augmentation improved the

  20. Augmentation Improves Human Cadaveric Vertebral Body Compression Mechanics For Lumbar Total Disc Replacement

    PubMed Central

    Yoder, Jonathon H.; Auerbach, Joshua D.; Maurer, Philip M.; Erbe, Erik M.; Entrekin, Dean; Balderston, Richard A.; Bertagnoli, Rudolf; Elliott, Dawn M.

    2012-01-01

    Study Design Cadaveric biomechanical study. Objectives Quantify the effects of vertebral body augmentation on biomechanics under axial compression by a total disc replacement (TDR) implant. Summary of Background Data TDR is a surgical alternative to lumbar spinal fusion to treat degenerative disc disease. Osteoporosis in the adjacent vertebrae to the interposed TDR may lead to implant subsidence or vertebral body fracture. Vertebral augmentation is used to treat osteoporotic compression fracture. The study sought to evaluate whether vertebral augmentation improves biomechanics under TDR axial loading. Methods Forty-five L1-L5 lumbar vertebral body segments with intact posterior elements were used. Peripheral quantitative computed tomography scans were performed to determine bone density, block randomizing specimens by bone density into augmentation and control groups. A semi-constrained keeled lumbar disc replacement device was implanted providing 50% endplate coverage. Vertebral augmentation of 17.6 ± 0.9% vertebral volume fill with Cortoss was performed on augmentation group. All segments underwent axial compression at a rate of 0.2 mm/s to 6mm. Results The load-displacement response for all specimens was non-linear. Subfailure mechanical properties with augmentation were significantly different from control; in all cases the augmented group was 2× higher than control. At failure, the maximum load and stiffness with augmentation was not significantly different from control. The maximum apparent stress and modulus with augmentation were 2× and 1.3× greater than control, respectively. The subfailure stress and apparent modulus with augmentation was moderately correlated with bone density while the control subfailure properties were not. The augmented maximum stress was not correlated with bone density, while the control was weakly correlated. The maximum apparent modulus was moderately correlated with bone density for both the augmented and control groups

  1. Official Executive Summary of an American Thoracic Society/American College of Chest Physicians Clinical Practice Guideline: Liberation from Mechanical Ventilation in Critically Ill Adults.

    PubMed

    Schmidt, Gregory A; Girard, Timothy D; Kress, John P; Morris, Peter E; Ouellette, Daniel R; Alhazzani, Waleed; Burns, Suzanne M; Epstein, Scott K; Esteban, Andres; Fan, Eddy; Ferrer, Miguel; Fraser, Gilles L; Gong, Michelle Ng; L Hough, Catherine; Mehta, Sangeeta; Nanchal, Rahul; Patel, Sheena; Pawlik, Amy J; Schweickert, William D; Sessler, Curtis N; Strøm, Thomas; Wilson, Kevin C; Truwit, Jonathon D

    2017-01-01

    This clinical practice guideline addresses six questions related to liberation from mechanical ventilation in critically ill adults. It is the result of a collaborative effort between the American Thoracic Society and the American College of Chest Physicians. A multidisciplinary panel posed six clinical questions in a Population, Intervention, Comparator, and Outcomes format. A comprehensive literature search and evidence synthesis was performed for each question, which included appraising the certainty in the evidence (i.e., the quality of evidence) using the Grading of Recommendations, Assessment, Development, and Evaluation approach. The Evidence-to-Decision framework was applied to each question, requiring the panel to evaluate and weigh the importance of the problem, the confidence in the evidence, the certainty about how much the public values the main outcomes, the magnitude and balance of desirable and undesirable outcomes, the resources and costs associated with the intervention, the impact on health disparities, and the acceptability and feasibility of the intervention. Evidence-based recommendations were formulated and graded initially by subcommittees and then modified after full-panel discussions. The recommendations were confirmed by confidential electronic voting; approval required that at least 80% of the panel members agree with the recommendation. The panel provides recommendations regarding liberation from mechanical ventilation. The details regarding the evidence and rationale for each recommendation are presented in the American Journal of Respiratory and Critical Care Medicine and Chest.

  2. Determination of the mechanical properties of solid and cellular polymeric dosage forms by diametral compression.

    PubMed

    Blaesi, Aron H; Saka, Nannaji

    2016-07-25

    At present, the immediate-release solid dosage forms, such as the oral tablets and capsules, are granular solids. They release drug rapidly and have adequate mechanical properties, but their manufacture is fraught with difficulties inherent in processing particulate matter. Such difficulties, however, could be overcome by liquid-based processing. Therefore, we have recently introduced polymeric cellular (i.e., highly porous) dosage forms prepared from a melt process. Experiments have shown that upon immersion in a dissolution medium, the cellular dosage forms with polyethylene glycol (PEG) as excipient and with predominantly open-cell topology disintegrate by exfoliation, thus enabling rapid drug release. If the volume fraction of voids of the open-cell structures is too large, however, their mechanical strength is adversely affected. At present, the common method for determining the tensile strength of brittle, solid dosage forms (such as select granular forms) is the diametral compression test. In this study, the theory of diametral compression is first refined to demonstrate that the relevant mechanical properties of ductile and cellular solids (i.e., the elastic modulus and the yield strength) can also be extracted from this test. Diametral compression experiments are then conducted on PEG-based solid and cellular dosage forms. It is found that the elastic modulus and yield strength of the open-cell structures are about an order of magnitude smaller than those of the non-porous solids, but still are substantially greater than the stiffness and strength requirements for handling the dosage forms manually. This work thus demonstrates that melt-processed polymeric cellular dosage forms that release drug rapidly can be designed and manufactured to have adequate mechanical properties. Copyright © 2016. Published by Elsevier B.V.

  3. Mechanical and thermal hyperalgesia and ectopic neuronal discharge after chronic compression of dorsal root ganglia.

    PubMed

    Song, X J; Hu, S J; Greenquist, K W; Zhang, J M; LaMotte, R H

    1999-12-01

    Chronic compression of the dorsal root ganglion (CCD) was produced in adult rats by implanting a stainless steel rod unilaterally into the intervertebral foramen, one rod at L(4) and another at L(5). Two additional groups of rats received either a sham surgery or an acute injury consisting of a transient compression of the ganglion. Withdrawal of the hindpaw was used as evidence of a nocifensive response to mechanical and thermal stimulation of the plantar surface. In addition, extracellular electrophysiological recordings of spontaneous discharges were obtained from dorsal root fibers of formerly compressed ganglia using an in vitro nerve-DRG-dorsal root preparation. The mean threshold force of punctate indentation and the mean threshold temperature of heating required to elicit a 50% incidence of foot withdrawal ipsilateral to the CCD were significantly lower than preoperative values throughout the 35 days of postoperative testing. The number of foot withdrawals ipsilateral to the CCD during a 20-min contact with a temperature-controlled floor was significantly increased over preoperative values throughout postoperative testing when the floor was 4 degrees C (hyperalgesia) and, to a lesser extent, when it was 30 degrees C (spontaneous pain). Stroking the foot with a cotton wisp never elicited a reflex withdrawal before surgery but did so in most rats tested ipsilateral to the CCD during the first 2 postoperative weeks. In contrast, the CCD produced no changes in responses to mechanical or thermal stimuli on the contralateral foot. The sham operation and acute injury produced no change in behavior other than slight, mechanical hyperalgesia for approximately 1 day, ipsilateral to the acute injury. Ectopic spontaneous discharges generated within the chronically compressed ganglion and, occurring in the absence of blood-borne chemicals and without an intact sympathetic nervous system, were recorded from neurons with intact, conducting, myelinated or unmyelinated

  4. Hydrous Ringwoodite: Clarifying Defect Mechanisms Through Combined Single-Crystal Refinement, Compressibility, and IR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Panero, W. R.; Smyth, J. R.; Jacobsen, S. D.; Frost, D. J.; Reaman, D. M.; Pigott, J. S.; Thomas, S.; Liu, Z.

    2009-12-01

    Incorporation of hydrogen into mantle silicates reduces bulk density and compressibility by varying amounts through associated defects. As the stiffest of the olivine polymorphs, ringwoodite should experience the greatest effects of hydration. We have synthesized Mg ringwoodite (γ-Mg2SiO4) with 2.6 wt% H2O at 20 GPa and 1250°C in the 5000 ton multi-anvil press at Bayerisches Geoinstitut and refined the crystal structure at ambient conditions from single-crystal X-ray diffraction data. The unit cell length is 8.0829(3) Å. The hydration mechanism is principally by octahedral cation vacancy with possible minor tetrahedral vacancy at a ratio of ~7:1. To further clarify the defect mechanism, we report low-temperature, ambient-pressure FTIR together with room temperature compression in a quasi-hydrostatic neon pressure medium to 23 GPa. FTIR spectra of this sample as well as one with about half the water content show three primary overlapping OH stretching bands at 2534, 3125, and 3622 cm-1 at ambient pressure and 300 K. Cooling to 11 K shows just 3% reduction of the width of the main 3125 cm-1 OH band, whereas the peak width reduction was recovered upon heating to room temperature. The sample with the lower water content shows splitting of the primary 3125 cm-1 peak, to 3089 and 3263 cm-1 at temperatures below 120 K. We interpret these results to indicate that the high water storage capacity of ringwoodite results from a combination of multiple bonding sites and loosely bound hydrogen dominated by cation vacancies. The 300 K isothermal bulk modulus (K0) and its pressure derivative (K’=dK0/dP) are 160.7(1.1) GPa and 5.0(2) respectively. Compared with nominally anhydrous ringwoodite, we observe a 12% decrease in the bulk modulus and a measurable increase in K’. The data indicate some evidence οf a change in compression mechanism at ~15 GPa, possibly resulting from a shift from initial compression of vacancies to more uniform compression of the structure

  5. Mechanisms of compressive deformation and failure of porous bulk metallic glasses

    NASA Astrophysics Data System (ADS)

    Gouripriya, S.; Tandaiya, Parag

    2017-06-01

    Bulk metallic glasses (BMGs) are a new class of engineering materials having strengths as high as 10 times that of conventional steels, but show no significant plastic strain at fracture. By introducing pores, their strain to failure has been shown to improve under uniaxial compression. In this work, three-dimensional finite element simulations of uniaxial compression are carried out on Pd-based porous BMGs having a wide range of pore volume fraction (1.9%-60%) with emphasis on understanding the underlying deformation and failure mechanisms. The resulting stress-strain curves agree reasonably well with existing experimental results. The simulations clearly bring out different failure mechanisms in low porosity BMGs and high porosity BMG foams. For low porosity BMGs (below 20%), the deformation and failure involves nucleation of shear bands around the pore diameter, linking of the shear bands with adjacent pores finally leading to initiation of ductile cracking within the shear bands. For high porosity BMG foams, the mechanism of deformation involves reduction in porosity of the material, self-contact of the pores, and their collapse on themselves causing densification of the material leading to apparent hardening in the stress strain behavior. The effect of pore geometry is also studied by considering ellipsoidal pores of volume fraction 3% and 11%. For ellipsoidal pores, the failure mechanisms are found to differ significantly when the orientation of the major axis of the pore vis-a-vis the loading axis is changed.

  6. Influence of Tension-Compression Asymmetry on the Mechanical Behavior of AZ31B Magnesium Alloy Sheets in Bending

    NASA Astrophysics Data System (ADS)

    Zhou, Ping; Beeh, Elmar; Friedrich, Horst E.

    2016-03-01

    Magnesium alloys are promising materials for lightweight design in the automotive industry due to their high strength-to-mass ratio. This study aims to study the influence of tension-compression asymmetry on the radius of curvature and energy absorption capacity of AZ31B-O magnesium alloy sheets in bending. The mechanical properties were characterized using tension, compression, and three-point bending tests. The material exhibits significant tension-compression asymmetry in terms of strength and strain hardening rate due to extension twinning in compression. The compressive yield strength is much lower than the tensile yield strength, while the strain hardening rate is much higher in compression. Furthermore, the tension-compression asymmetry in terms of r value (Lankford value) was also observed. The r value in tension is much higher than that in compression. The bending results indicate that the AZ31B-O sheet can outperform steel and aluminum sheets in terms of specific energy absorption in bending mainly due to its low density. In addition, the AZ31B-O sheet was deformed with a larger radius of curvature than the steel and aluminum sheets, which brings a benefit to energy absorption capacity. Finally, finite element simulation for three-point bending was performed using LS-DYNA and the results confirmed that the larger radius of curvature of a magnesium specimen is mainly attributed to the high strain hardening rate in compression.

  7. Mechanical response of porcine skin under compression from low to high strain rates

    NASA Astrophysics Data System (ADS)

    Bo, Chiara; Butler, Ben; Williams, Alun; Brown, Katherine; Proud, William

    2013-06-01

    Uniaxial compression experiments were performed on fresh porcine skin samples at different strain rates to study the stress-strain response. Low strain rate experiments were performed with an Instron 5566, while high strain rates were achieved using a Split Hopkinson Pressure Bar system. Magnesium bars and semiconductor strain gauges were used respectively to maximize the signal transmission from porcine skin to the output bar and to allow the signal measurement. Skin samples were harvested from different area of the animal to investigate the heterogeneity of such material. The experimental results showed that the mechanical response of skin in compression is strongly dependent on the strain rate of loading and on the location from which the samples were collected. Specimens collected from the rump showed a stiffer response compared to samples harvested from the thigh. Finally, a histological analysis of the samples post compression was carried out to examine the extent of tissue damage as a function of strain rate. This work is supported by the Atomic Weapons Establishment, UK and The Royal British Legion Centre for Blast Injury Studies at Imperial College London, UK.

  8. Ischemic compression block attenuates mechanical hyperalgesia evoked from latent myofascial trigger points.

    PubMed

    Wang, Yong-Hui; Ding, Xin-Li; Zhang, Yang; Chen, Jing; Ge, Hong-You; Arendt-Nielsen, Lars; Yue, Shou-Wei

    2010-04-01

    The aim of the present study is to test the hypothesis that large-diameter myelinated muscle afferents contribute to the pathophysiology of myofascial trigger points (MTrPs). The ischemic compression blockage (ICB) of large-diameter myelinated muscle afferents was obtained with a 7-cm-wide tourniquet applied around the upper arm proximal to the brachioradialis muscle in 20 healthy subjects. This study consisted of two randomized sessions with an interval of 1 week in between each session. In one session, pressure pain threshold (PPT) and pressure threshold for eliciting referred pain (PTRP) were measured at an MTrP region in the brachioradialis muscle in one forearm. In another session, PPT was measured at a non-MTrP region in the brachioradialis muscle of the contralateral forearm at the time of pre-compression, 20 min following compression, and 10 min after decompression. The results showed that ICB, which mainly blocks large-diameter myelinated muscle afferents, was associated with an increase in PPT and PTRP (all P < 0.001) at MTrP regions but not at non-MTrP regions. These results suggest that large-diameter muscle afferents may be involved in pain and mechanical hyperalgesia at MTrPs.

  9. Mechanical behavior and microstructure of compressed Ti foams synthesized via freeze casting.

    PubMed

    Jenei, Péter; Choi, Hyelim; Tóth, Adrián; Choe, Heeman; Gubicza, Jenő

    2016-10-01

    Pure Ti and Ti-5%W foams were prepared via freeze casting. The porosity and grain size of both the materials were 32-33% and 15-17µm, respectively. The mechanical behavior of the foams was investigated by uniaxial compression up to a plastic strain of ~0.26. The Young׳s moduli of both foams were ~23GPa, which was in good agreement with the value expected from their porosity. The Young׳s moduli of the foams were similar to the elastic modulus of cortical bones, thereby eliminating the osteoporosis-causing stress-shielding effect. The addition of W increased the yield strength from ~196MPa to ~235MPa. The microstructure evolution in the grains during compression was studied using electron backscatter diffraction (EBSD) and X-ray line profile analysis (XLPA). After compression up to a plastic strain of ~0.26, the average dislocation densities increased to ~3.4×10(14)m(-2) and ~5.9×10(14)m(-2) in the Ti and Ti-W foams, respectively. The higher dislocation density in the Ti-W foam can be attributed to the pinning effect of the solute tungsten atoms on dislocations. The experimentally measured yield strength was in good agreement with the strength calculated from the dislocation density and porosity. This study demonstrated that the addition of W to Ti foam is beneficial for biomedical applications, because the compressive yield strength increased while its Young׳s modulus remained similar to that of cortical bones.

  10. Mechanical properties of the human spinal cord under the compressive loading.

    PubMed

    Karimi, Alireza; Shojaei, Ahmad; Tehrani, Pedram

    2017-07-15

    The spinal cord as the most complex and critical part of the human body is responsible for the transmission of both motor and sensory impulses between the body and the brain. Due to its pivotal role any types of physical injury in that disrupts its function following by shortfalls, including the minor motor and sensory malfunctions as well as complicate quadriplegia and lifelong ventilator dependency. In order to shed light on the injuries to the spinal cord, the application of the computational models to simulate the trauma impact loading to that are deemed required. Nonetheless, it has not been fulfilled since there is a paucity of knowledge about the mechanical properties of the spinal cord, especially the cervical one, under the compressive loading on the grounds of the difficulty in obtaining this tissue from the human body. This study was aimed at experimentally measuring the mechanical properties of the human cervical spinal cord of 24 isolated fresh samples under the unconfined compressive loading at a relatively low strain rate. The stress-strain data revealed the elastic modulus and maximum/failure stress of 40.12±6.90 and 62.26±5.02kPa, respectively. Owing to the nonlinear response of the spinal cord, the Yeoh, Ogden, and Mooney-Rivlin hyperelastic material models have also been employed. The results may have implications not only for understanding the linear elastic and nonlinear hyperelastic mechanical properties of the cervical spinal cord under the compressive loading, but also for providing a raw data for investigating the injury as a result of the trauma thru the numerical simulations. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. The compressive mechanical properties of diabetic and non-diabetic plantar soft tissue

    PubMed Central

    Pai, Shruti; Ledoux, William R.

    2010-01-01

    Diabetic subjects are at an increased risk of developing plantar ulcers. Knowledge of the physiologic compressive properties of the plantar soft tissue is critical to understanding possible mechanisms of ulcer formation and improving treatment options. The purpose of this study was to determine the compressive mechanical properties of the plantar soft tissue in both diabetic and non-diabetic specimens from six relevant locations beneath the foot, namely the hallux (big toe), first, third, and fifth metatarsal heads, lateral midfoot, and calcaneus (heel). Cylindrical specimens (1.905cm diameter) from these locations were excised and separated from the skin and bone from 4 diabetic and 4 non-diabetic age-matched, elderly, fresh-frozen cadaveric feet. Specimens were then subjected to biomechanically realistic strains of ∼50% in compression using triangle wave tests conducted at five frequencies ranging from 1 to 10 Hz to determine tissue modulus, energy loss, and strain rate dependence. Diabetic vs. non-diabetic results across all specimens, locations, and testing frequencies demonstrated altered mechanical properties with significantly increased modulus (1146.7 vs. 593.0kPa) but no change in energy loss (68.5 vs. 67.9%). All tissue demonstrated strain rate dependence and tissue beneath the calcaneus was found to have decreased modulus and energy loss compared to other areas. The results of this study could be used to generate material properties for all areas of the plantar soft tissue in diabetic or non-diabetic feet, with implications for foot computational modeling efforts and potentially for pressure alleviating footwear that could reduce plantar ulcer incidence. PMID:20207359

  12. The roles of mechanical compression and chemical irritation in regulating spinal neuronal signaling in painful cervical nerve root injury.

    PubMed

    Zhang, Sijia; Nicholson, Kristen J; Smith, Jenell R; Gilliland, Taylor M; Syré, Peter P; Winkelstein, Beth A

    2013-11-01

    Both traumatic and slow-onset disc herniation can directly compress and/or chemically irritate cervical nerve roots, and both types of root injury elicit pain in animal models of radiculopathy. This study investigated the relative contributions of mechanical compression and chemical irritation of the nerve root to spinal regulation of neuronal activity using several outcomes. Modifications of two proteins known to regulate neurotransmission in the spinal cord, the neuropeptide calcitonin gene-related peptide (CGRP) and glutamate transporter 1 (GLT-1), were assessed in a rat model after painful cervical nerve root injuries using a mechanical compression, chemical irritation or their combination of injury. Only injuries with compression induced sustained behavioral hypersensitivity (p≤0.05) for two weeks and significant decreases (p<0.037) in CGRP and GLT-1 immunoreactivity to nearly half that of sham levels in the superficial dorsal horn. Because modification of spinal CGRP and GLT-1 is associated with enhanced excitatory signaling in the spinal cord, a second study evaluated the electrophysiological properties of neurons in the superficial and deeper dorsal horn at day 7 after a painful root compression. The evoked firing rate was significantly increased (p=0.045) after compression and only in the deeper lamina. The painful compression also induced a significant (p=0.002) shift in the percentage of neurons in the superficial lamina classified as low- threshold mechanoreceptive (sham 38%; compression 10%) to those classified as wide dynamic range neurons (sham 43%; compression 74%). Together, these studies highlight mechanical compression as a key modulator of spinal neuronal signaling in the context of radicular injury and pain.

  13. Analysis of an evaporator-condenser-separated mechanical vapor compression system

    NASA Astrophysics Data System (ADS)

    Wu, Hong; Li, Yulong; Chen, Jiang

    2013-04-01

    An evaporator-condenser-separated mechanical vapor compression (MVC) system was presented. The better effect of descaling and antiscaling was obtained by the new system. This study focused on the method of thermodynamic analysis, and the energy and exergy flow diagrams were established by using the first and second law of thermodynamics analysis. The results show that the energy utilization rate is very high and the specific power consumption is low. Exergy analysis indicates that the exergy efficiency is low, and the largest exergy loss occurs within the evaporator -condenser and the compressor.

  14. Anisotropy in the compressive mechanical properties of bovine cortical bone and the mineral and protein constituents.

    PubMed

    Novitskaya, Ekaterina; Chen, Po-Yu; Lee, Steve; Castro-Ceseña, Ana; Hirata, Gustavo; Lubarda, Vlado A; McKittrick, Joanna

    2011-08-01

    The mechanical properties of fully demineralized, fully deproteinized and untreated cortical bovine femur bone were investigated by compression testing in three anatomical directions (longitudinal, radial and transverse). The weighted sum of the stress-strain curves of the treated bones was far lower than that of the untreated bone, indicating a strong molecular and/or mechanical interaction between the collagen matrix and the mineral phase. Demineralization and deproteinization of the bone demonstrated that contiguous, stand-alone structures result, showing that bone can be considered an interpenetrating composite material. Structural features of the samples from all groups were studied by optical and scanning electron microscopy. Anisotropic mechanical properties were observed: the radial direction was found to be the strongest for untreated bone, while the longitudinal one was found to be the strongest for deproteinized and demineralized bones. A possible explanation for this phenomenon is the difference in bone microstructure in the radial and longitudinal directions.

  15. A high-compression electron gun for C6+ production: concept, simulations and mechanical design

    NASA Astrophysics Data System (ADS)

    Mertzig, Robert; Breitenfeldt, M.; Mathot, S.; Pitters, J.; Shornikov, A.; Wenander, F.

    2017-07-01

    In this paper we report on simulations and the mechanical design of a high-compression electron gun for an Electron Beam Ion Source (EBIS) dedicated for production of high intensity and high repetition rate pulses of bare carbon ions for injection into linac-based hadron therapy facilities. The gun is presently under construction at CERN to be retrofitted into the TwinEBIS test bench for experimental studies. We describe the design constraints, show results of numeric simulations and report on the mechanical design featuring several novel ideas. The reported design makes use of combined-function units with reduced number of mechanical joints that were carefully controlled and tuned during the manufacturing phase. The simulations addressed a wide range of topics including the influence of thermal effects, focusing optics, symmetry-breaking misalignments and injection into a full 5 T field.

  16. A comparison of the therapeutic effectiveness of and preference for postural drainage and percussion, intrapulmonary percussive ventilation, and high-frequency chest wall compression in hospitalized cystic fibrosis patients.

    PubMed

    Varekojis, Sarah M; Douce, F Herbert; Flucke, Robert L; Filbrun, David A; Tice, Jill S; McCoy, Karen S; Castile, Robert G

    2003-01-01

    Cystic fibrosis (CF) patients have abnormally viscid bronchial secretions that cause airway obstruction, inflammation, and infection that leads to lung damage. To enhance airway clearance and reduce airway obstruction, daily bronchopulmonary hygiene therapy is considered essential. Compare the effectiveness of and patient preferences regarding 3 airway clearance methods: postural drainage and percussion (PD&P), intrapulmonary percussive ventilation (IPV), and high-frequency chest wall compression (HFCWC). The participants were hospitalized CF patients >or= 12 years old. Effectiveness was evaluated by measuring the wet and dry weights of sputum obtained with each method. In random order, each patient received 2 consecutive days of each therapy, delivered 3 times daily for 30 minutes. Sputum was collected during and for 15 minutes after each treatment, weighed wet, then dried and weighed again. Participants rated their preferences using a Likert-type scale. Mean weights and preferences were compared using analysis of variance with repeated measures. Patient preferences were compared using Freidman's test. Twenty-four patients were studied. The mean +/- SD wet sputum weights were 5.53 +/- 5.69 g with PD&P, 6.84 +/- 5.41 g with IPV, and 4.77 +/- 3.29 g with HFCWC. The mean wet sputum weights differed significantly (p = 0.035). Wet sputum weights from IPV were significantly greater than those from HFCWC (p < 0.05). The mean dry sputum weights were not significantly different. With regard to overall preference and to the subcomponents of preference, none of the 3 methods was preferred over the others. HFCWC and IPV are at least as effective as vigorous, professionally administered PD&P for hospitalized CF patients, and the 3 modalities were equally acceptable to them. A hospitalized CF patient should try each therapy and choose his or her preferred modality.

  17. Test-retest reliability of expiratory abdominal compression with a handheld dynamometer in patients with prolonged mechanical ventilation

    PubMed Central

    Morino, Akira; Shida, Masahiro; Tanaka, Masashi; Sato, Kimihiro; Seko, Toshiaki; Ito, Shunsuke; Ogawa, Shunichi; Takahashi, Naoaki

    2015-01-01

    [Purpose] The present study aimed to examine the test-retest reliability of expiratory abdominal compression with a handheld dynamometer in patients with prolonged mechanical ventilation. [Subjects and Methods] We recruited 18 patients with prolonged mechanical ventilation. All patients had impaired consciousness. The mode of the ventilator was synchronized intermittent mandatory ventilation. The abdomen above the navel was vertically compressed using a handheld dynamometer in synchronization with expiration. Expiratory abdominal compression was performed two times. We measured the tidal volume during expiratory abdominal compression. There was an interval of 5 minutes between the first and second measurements. Intraclass correlation coefficient (ICC) and Bland-Altman analysis were performed to examine the test-retest reliability of expiratory abdominal compression with a handheld dynamometer. [Results] The test-retest reliability of expiratory abdominal compression was excellent (ICC(1, 1): 0.987). Bland-Altman analysis showed that there was no fixed bias and no proportional bias. [Conclusion] The findings of this study suggest that expiratory abdominal compression with a handheld dynamometer is reliable and useful for patients with respiratory failure and prolonged mechanical ventilation. PMID:26311946

  18. Test-retest reliability of expiratory abdominal compression with a handheld dynamometer in patients with prolonged mechanical ventilation.

    PubMed

    Morino, Akira; Shida, Masahiro; Tanaka, Masashi; Sato, Kimihiro; Seko, Toshiaki; Ito, Shunsuke; Ogawa, Shunichi; Takahashi, Naoaki

    2015-07-01

    [Purpose] The present study aimed to examine the test-retest reliability of expiratory abdominal compression with a handheld dynamometer in patients with prolonged mechanical ventilation. [Subjects and Methods] We recruited 18 patients with prolonged mechanical ventilation. All patients had impaired consciousness. The mode of the ventilator was synchronized intermittent mandatory ventilation. The abdomen above the navel was vertically compressed using a handheld dynamometer in synchronization with expiration. Expiratory abdominal compression was performed two times. We measured the tidal volume during expiratory abdominal compression. There was an interval of 5 minutes between the first and second measurements. Intraclass correlation coefficient (ICC) and Bland-Altman analysis were performed to examine the test-retest reliability of expiratory abdominal compression with a handheld dynamometer. [Results] The test-retest reliability of expiratory abdominal compression was excellent (ICC(1, 1): 0.987). Bland-Altman analysis showed that there was no fixed bias and no proportional bias. [Conclusion] The findings of this study suggest that expiratory abdominal compression with a handheld dynamometer is reliable and useful for patients with respiratory failure and prolonged mechanical ventilation.

  19. Mechanical properties and deformation mechanism of Al2O3 determined from in situ transmission electron microscopy compression

    NASA Astrophysics Data System (ADS)

    Lin, Kai-Peng; Stachiv, Ivo; Fang, Te-Hua

    2017-07-01

    The mechanical properties and deformation mechanism of alumina (Al2O3) ceramic nanopillars and microstructures have been studied using in situ transmission electron microscopy (TEM) compression and nanoindentation experiments. It has been found that the Young’s modulus of Al2O3 nanopillars significantly increases with a decrease of its thickness; it ranges from 54.8 GPa for the nanopillar of radius 175 nm to 347.5 GPa for the one of radius of 75 nm. The hardness of Al2O3 microstructures estimated by the nanoindentation is between 3.19 to 20.60 GPa. The Raman spectra of Al2O3 substrate has a production peak (577.3 cm-1) between 418.3 and 645.2 (cm-1) peaks. The strain hardening behavior of Al2O3 microstructures has been observed and the impact of size on the compressive and bending behavior of Al2O3 micro-pillared structures is also examined and explained.

  20. Compression fatigue behavior and failure mechanism of porous titanium for biomedical applications.

    PubMed

    Li, Fuping; Li, Jinshan; Huang, Tingting; Kou, Hongchao; Zhou, Lian

    2017-01-01

    Porous titanium and its alloys are believed to be one of the most attractive biomaterials for orthopedic implant applications. In the present work, porous pure titanium with 50-70% porosity and different pore size was fabricated by diffusion bonding. Compression fatigue behavior was systematically studied along the out-of-plane direction. It resulted that porous pure titanium has anisotropic pore structure and the microstructure is fine-grained equiaxed α phase with a few twins in some α grains. Porosity and pore size have some effect on the S-N curve but this effect is negligible when the fatigue strength is normalized by the yield stress. The relationship between normalized fatigue strength and fatigue life conforms to a power law. The compression fatigue behavior is characteristic of strain accumulation. Porous titanium experiences uniform deformation throughout the entire sample when fatigue cycle is lower than a critical value (NT). When fatigue cycles exceed NT, strain accumulates rapidly and a single collapse band forms with a certain angle to the loading direction, leading to the sudden failure of testing sample. Both cyclic ratcheting and fatigue crack growth contribute to the fatigue failure mechanism, while the cyclic ratcheting is the dominant one. Porous titanium possesses higher normalized fatigue strength which is in the range of 0.5-0.55 at 10(6) cycles. The reasons for the higher normalized fatigue strength were analyzed based on the microstructure and fatigue failure mechanism. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Simulation of mechanical performance of nanoporous FCC copper under compression with pores mimicking several crystalline arrays

    NASA Astrophysics Data System (ADS)

    Cui, Yi; Chen, Zengtao

    2017-08-01

    The mechanical performance of porous metal with assembly of pores mimicking typical crystalline structures is studied via atomistic simulation and finite element method. The pore lattices are made with the same orientation as the face-centered cubic (FCC) copper lattice. The compression is applied in the [0 0 1] direction. Under the same initial porosity and identical pore size, pores assembled in diamond array result in a superior stress response under compression. The sample with pores assembled in body-centered cubic array, whose surface-to-volume ratio is close to that of either FCC or hexagonally close-packed (HCP) array, has a yet much higher yield stress. However, the FCC- and HCP-structured nanoporous samples exhibit a greater hardening effect. The Lubarda model for critical stress to trigger dislocation emission is extended to the nanoporous geometry numerically. The magnitude and distribution of shear stress on the slip plane are found crucial to dislocation activities. No strong correlation between dislocation formation and early densification of nanoporous geometry is found. Through comparing the yielding and hardening behavior among differently structured nanoporous samples, new understanding could be established on their mechanical performance. Enhanced structural integrity could better support their diverse applications by design.

  2. A device for simultaneous live cell imaging during uni-axial mechanical strain or compression.

    PubMed

    Gerstmair, Axel; Fois, Giorgio; Innerbichler, Siegfried; Dietl, Paul; Felder, Edward

    2009-08-01

    Mechanical stimuli control multiple cellular processes such as secretion, growth, and differentiation. A widely used method to investigate cell strain ex vivo is stretching an elastic membrane to which cells adhere. However, simultaneous imaging of dynamic signals from single living cells grown on elastic substrates during uni-axial changes of cell length is usually hampered by the movement of the sample along the strain axis out of the narrow optical field of view. We used a thin, prestrained, elastic chamber as growth substrate for the cells and deformed the chamber with a computer-controlled stretch device. An algorithm that compensates the lateral displacement during stretch kept any selected point of the whole chamber at a constant position on the microscope during strain or relaxation (compression). Adherent cells or other materials that adhere to the bottom of the chamber at any given position could be imaged during controlled positive (stretch) or negative (compression) changes of cell length. The system was tested on living alveolar type II cells, in which mechanical effects on secretion have been intensively investigated in the past.

  3. Effects of fatigue on microstructure and mechanical properties of bone organic matrix under compression.

    PubMed

    Trębacz, Hanna; Zdunek, Artur; Cybulska, Justyna; Pieczywek, Piotr

    2013-03-01

    The aim of the study was to investigate whether a fatigue induced weakening of cortical bone was revealed in microstructure and mechanical competence of demineralized bone matrix. Two types of cortical bone samples (plexiform and Haversian) were use. Bone slabs from the midshaft of bovine femora were subjected to cyclical bending. Fatigued and adjacent control samples were cut into cubes and demineralized in ethylenediaminetetraacetic acid. Demineralized samples were either subjected to microscopic quantitative image analysis, or compressed to failure (in longitudinal or transverse direction) with a simultaneous analysis of acoustic emission (AE). In fatigued samples porosity of organic matrix and average area of pores have risen, along with a change in the pores shape. The effect of fatigue depended on the type of the bone, being more pronounced in the plexiform than in Haversian tissue. Demineralized bone matrix was anisotropic under compressive loads in both types of cortical structure. The main result of fatigue pretreatment on mechanical parameters was a significant decrease of ultimate strain in the transverse direction in plexiform samples. The decrease of strain in this group was accompanied by a considerable increase of the fraction of large pores and a significant change in AE energy.

  4. Understanding deformation mechanisms during powder compaction using principal component analysis of compression data.

    PubMed

    Roopwani, Rahul; Buckner, Ira S

    2011-10-14

    Principal component analysis (PCA) was applied to pharmaceutical powder compaction. A solid fraction parameter (SF(c/d)) and a mechanical work parameter (W(c/d)) representing irreversible compression behavior were determined as functions of applied load. Multivariate analysis of the compression data was carried out using PCA. The first principal component (PC1) showed loadings for the solid fraction and work values that agreed with changes in the relative significance of plastic deformation to consolidation at different pressures. The PC1 scores showed the same rank order as the relative plasticity ranking derived from the literature for common pharmaceutical materials. The utility of PC1 in understanding deformation was extended to binary mixtures using a subset of the original materials. Combinations of brittle and plastic materials were characterized using the PCA method. The relationships between PC1 scores and the weight fractions of the mixtures were typically linear showing ideal mixing in their deformation behaviors. The mixture consisting of two plastic materials was the only combination to show a consistent positive deviation from ideality. The application of PCA to solid fraction and mechanical work data appears to be an effective means of predicting deformation behavior during compaction of simple powder mixtures.

  5. Influence of the mechanical stress and the filler content on the hydrostatic compression behaviour of natural rubber

    NASA Astrophysics Data System (ADS)

    Zimmermann, Jan; Stommel, Markus

    2013-12-01

    The behaviour of natural rubber (NR) compounds under mechanical stress is often reported in literature. An important and widely discussed effect that occurs is the Mullins effect. During the first loading cycles in a tensile test for example, a stress-softening effect is observed. This and other effects on the mechanical behaviour are investigated for different rubber materials with and without different types of fillers and filler contents. Besides, the hydrostatic compression behaviour is affected by the type and content of filler as well, which is shown for an NR with and without waxes and different contents of carbon black (CB) in this contribution. In contrast to the Mullins effect, there is no dependence of the number of loading cycles on the volumetric behaviour determined in hydrostatic compression tests. Furthermore, the influence of the previous stress-softening due to mechanical stress on the compression behaviour is elaborated. Cyclic uniaxial tensile tests are performed to realize the stress-softening in the rubber materials. The subsequent compression tests are compared to compression tests without any pre-stretching to determine the influence of previous mechanical loading on the compression behaviour of natural rubber with different filler contents.

  6. Mechanical compression induces VEGFA overexpression in breast cancer via DNMT3A-dependent miR-9 downregulation

    PubMed Central

    Kim, Baek Gil; Gao, Ming-Qing; Kang, Suki; Choi, Yoon Pyo; Lee, Joo Hyun; Kim, Ji Eun; Han, Hyun Ho; Mun, Seong Gyeong; Cho, Nam Hoon

    2017-01-01

    Tumor growth generates mechanical compression, which may trigger mechanotransduction in cancer and stromal cells and promote tumor progression. However, very little is known about how compression stimulates signal transduction and contributes to tumor progression. In the present study, we demonstrated that compression enhances a tumor progression phenotype using an in vitro compression model, and validated the results from the in vitro model with high- and low-compressed breast cancer tissues. Mechanical compression induced miR-9 downregulation by DNMT3A-dependent promoter methylation in the MDA-MB-231 and BT-474 breast cancer cell lines and in cancer-associated fibroblasts. The overexpression of miR-9 target genes (LAMC2, ITGA6, and EIF4E) was induced by miR-9 downregulation, which eventually enhanced vascular endothelial growth factors production. Demethylation and decompression could reverse compression-induced miR-9 downregulation and following overexpression of miR-9 target genes and VEGFA. PMID:28252641

  7. Plasticity mechanisms in nanovoided b.c.c. metals under high strain rate compression

    NASA Astrophysics Data System (ADS)

    Ruestes, Carlos; Bringa, Eduardo; Stukowski, Alexander; Rodríguez Nieva, Joaquin; Bertolino, Graciela; Tang, Yizhe; Meyers, Marc

    2013-06-01

    Atomistic-scale simulations provide unique insights to plasticity mechanisms arising under extreme conditions where its relative nanoscopic length and time scales render experiments almost impossible. Our studies explore the mechanical response and plasticity effects under uniaxial high strain rate compression for a Ta single crystal with a collection of spherical nanovoids, with a radius of 3-4 nm, providing an initial porosity of 5%-20%. We examine strain rate effects, from 107/s to 1010/s, in the dislocation density and dislocation-induced heating. The resulting dislocation densities are in good agreement with experimental results for shock-recovered samples. This research was funded by the ANPCyT project PICT2008-1325, PICT2009-0092, PRH and 06/M035 from SecTyP-U.N.Cuyo and UC Research Labs.

  8. A reduced mechanism for biodiesel surrogates with low temperature chemistry for compression ignition engine applications

    NASA Astrophysics Data System (ADS)

    Luo, Zhaoyu; Plomer, Max; Lu, Tianfeng; Som, Sibendu; Longman, Douglas E.

    2012-04-01

    Biodiesel is a promising alternative fuel for compression ignition (CI) engines. It is a renewable energy source that can be used in these engines without significant alteration in design. The detailed chemical kinetics of biodiesel is however highly complex. In the present study, a skeletal mechanism with 123 species and 394 reactions for a tri-component biodiesel surrogate, which consists of methyl decanoate, methyl 9-decanoate and n-heptane was developed for simulations of 3-D turbulent spray combustion under engine-like conditions. The reduction was based on an improved directed relation graph (DRG) method that is particularly suitable for mechanisms with many isomers, followed by isomer lumping and DRG-aided sensitivity analysis (DRGASA). The reduction was performed for pressures from 1 to 100 atm and equivalence ratios from 0.5 to 2 for both extinction and ignition applications. The initial temperatures for ignition were from 700 to 1800 K. The wide parameter range ensures the applicability of the skeletal mechanism under engine-like conditions. As such the skeletal mechanism is applicable for ignition at both low and high temperatures. Compared with the detailed mechanism that consists of 3299 species and 10806 reactions, the skeletal mechanism features a significant reduction in size while still retaining good accuracy and comprehensiveness. The validations of ignition delay time, flame lift-off length and important species profiles were also performed in 3-D engine simulations and compared with the experimental data from Sandia National Laboratories under CI engine conditions.

  9. Chest wall hypoplasia--principles and treatment.

    PubMed

    Mayer, Oscar Henry

    2015-01-01

    The chest is a dynamic structure. For normal movement it relies on a coordinated movement of the multiple bones, joints and muscles of the respiratory system. While muscle weakness can have clear impact on respiration by decreasing respiratory motion, so can conditions that cause chest wall hypoplasia and produce an immobile chest wall. These conditions, such as Jarcho-Levin and Jeune syndrome, present significantly different challenges than those faced with early onset scoliosis in which chest wall mechanics and thoracic volume may be much closer to normal. Because of this difference more aggressive approaches to clinical and surgical management are necessary.

  10. PARAMETRIC STUDY OF TISSUE OPTICAL CLEARING BY LOCALIZED MECHANICAL COMPRESSION USING COMBINED FINITE ELEMENT AND MONTE CARLO SIMULATION.

    PubMed

    Vogt, William C; Shen, Haiou; Wang, Ge; Rylander, Christopher G

    2010-07-01

    Tissue Optical Clearing Devices (TOCDs) have been shown to increase light transmission through mechanically compressed regions of naturally turbid biological tissues. We hypothesize that zones of high compressive strain induced by TOCD pins produce localized water displacement and reversible changes in tissue optical properties. In this paper, we demonstrate a novel combined mechanical finite element model and optical Monte Carlo model which simulates TOCD pin compression of an ex vivo porcine skin sample and modified spatial photon fluence distributions within the tissue. Results of this simulation qualitatively suggest that light transmission through the skin can be significantly affected by changes in compressed tissue geometry as well as concurrent changes in tissue optical properties. The development of a comprehensive multi-domain model of TOCD application to tissues such as skin could ultimately be used as a framework for optimizing future design of TOCDs.

  11. Analysis of the mechanical behavior of chondrocytes in unconfined compression tests for cyclic loading.

    PubMed

    Wu, John Z; Herzog, Walter

    2006-01-01

    Experimental evidence indicates that the biosynthetic activity of chondrocytes is associated with the mechanical environment. For example, excessive, repetitive loading has been found to induce cell death, morphological and cellular damage, as seen in degenerative joint disease, while cyclic, physiological-like loading has been found to trigger a partial recovery of morphological and ultrastructural aspects in osteoarthritic human articular chondrocytes. Mechanical stimuli are believed to influence the biosynthetic activity via the deformation of cells. However, the in situ deformation of chondrocytes for cyclic loading conditions has not been investigated experimentally or theoretically. The purpose of the present study was to simulate the mechanical response of chondrocytes to cyclic loading in unconfined compression tests using a finite element model. The material properties of chondrocytes and extracellular matrix were considered to be biphasic. The time-histories of the shape and volume variations of chondrocytes at three locations (i.e., surface, center, and bottom) within the cartilage were predicted for static and cyclic loading conditions at two frequencies (0.02 and 0.1 Hz) and two amplitudes (0.1 and 0.2 MPa). Our results show that cells at different depths within the cartilage deform differently during cyclic loading, and that the depth dependence of cell deformation is influenced by the amplitude of the cyclic loading. Cell deformations under cyclic loading of 0.02 Hz were found to be similar to those at 0.1 Hz. We conclude from the simulation results that, in homogeneous cartilage layers, cell deformations are location-dependent, and further are affected by load magnitude. In physiological conditions, the mechanical environment of cells are even more complex due to the anisotropy, depth-dependent inhomogeneity, and tension-compression non-linearity of the cartilage matrix. Therefore, it is feasible to speculate that biosynthetic responses of

  12. Normal and Fibrotic Rat Livers Demonstrate Shear Strain Softening and Compression Stiffening: A Model for Soft Tissue Mechanics

    PubMed Central

    Cao, Xuan; van Oosten, Anne; Shenoy, Vivek B.; Janmey, Paul A.; Wells, Rebecca G.

    2016-01-01

    Tissues including liver stiffen and acquire more extracellular matrix with fibrosis. The relationship between matrix content and stiffness, however, is non-linear, and stiffness is only one component of tissue mechanics. The mechanical response of tissues such as liver to physiological stresses is not well described, and models of tissue mechanics are limited. To better understand the mechanics of the normal and fibrotic rat liver, we carried out a series of studies using parallel plate rheometry, measuring the response to compressive, extensional, and shear strains. We found that the shear storage and loss moduli G’ and G” and the apparent Young's moduli measured by uniaxial strain orthogonal to the shear direction increased markedly with both progressive fibrosis and increasing compression, that livers shear strain softened, and that significant increases in shear modulus with compressional stress occurred within a range consistent with increased sinusoidal pressures in liver disease. Proteoglycan content and integrin-matrix interactions were significant determinants of liver mechanics, particularly in compression. We propose a new non-linear constitutive model of the liver. A key feature of this model is that, while it assumes overall liver incompressibility, it takes into account water flow and solid phase compressibility. In sum, we report a detailed study of non-linear liver mechanics under physiological strains in the normal state, early fibrosis, and late fibrosis. We propose a constitutive model that captures compression stiffening, tension softening, and shear softening, and can be understood in terms of the cellular and matrix components of the liver. PMID:26735954

  13. Extracellular matrix integrity affects the mechanical behaviour of in-situ chondrocytes under compression.

    PubMed

    Moo, Eng Kuan; Han, Sang Kuy; Federico, Salvatore; Sibole, Scott C; Jinha, Azim; Abu Osman, Noor Azuan; Pingguan-Murphy, Belinda; Herzog, Walter

    2014-03-21

    Cartilage lesions change the microenvironment of cells and may accelerate cartilage degradation through catabolic responses from chondrocytes. In this study, we investigated the effects of structural integrity of the extracellular matrix (ECM) on chondrocytes by comparing the mechanics of cells surrounded by an intact ECM with cells close to a cartilage lesion using experimental and numerical methods. Experimentally, 15% nominal compression was applied to bovine cartilage tissues using a light-transmissible compression system. Target cells in the intact ECM and near lesions were imaged by dual-photon microscopy. Changes in cell morphology (N(cell)=32 for both ECM conditions) were quantified. A two-scale (tissue level and cell level) Finite Element (FE) model was also developed. A 15% nominal compression was applied to a non-linear, biphasic tissue model with the corresponding cell level models studied at different radial locations from the centre of the sample in the transient phase and at steady state. We studied the Green-Lagrange strains in the tissue and cells. Experimental and theoretical results indicated that cells near lesions deform less axially than chondrocytes in the intact ECM at steady state. However, cells near lesions experienced large tensile strains in the principal height direction, which are likely associated with non-uniform tissue radial bulging. Previous experiments showed that tensile strains of high magnitude cause an up-regulation of digestive enzyme gene expressions. Therefore, we propose that cartilage degradation near tissue lesions may be due to the large tensile strains in the principal height direction applied to cells, thus leading to an up-regulation of catabolic factors. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Chest x-ray

    MedlinePlus

    Chest radiography; Serial chest x-ray; X-ray - chest ... You stand in front of the x-ray machine. You will be told to hold your breath when the x-ray is taken. Two images are usually taken. You will ...

  15. Mechanism for amorphization of boron carbide B{sub 4}C under uniaxial compression

    SciTech Connect

    Aryal, Sitaram; Rulis, Paul; Ching, W. Y.

    2011-11-01

    Boron carbide undergoes an amorphization transition under high-velocity impacts, causing it to suffer a catastrophic loss in strength. The failure mechanism is not clear and this limits the ways to improve its resistance to impact. To help uncover the failure mechanism, we used ab initio methods to carry out large-scale uniaxial compression simulations on two polytypes of stoichiometric boron carbide (B{sub 4}C), B{sub 11}C-CBC, and B{sub 12}-CCC, where B{sub 11}C or B{sub 12} is the 12-atom icosahedron and CBC or CCC is the three-atom chain. The simulations were performed on large supercells of 180 atoms. Our results indicate that the B{sub 11}C-CBC (B{sub 12}-CCC) polytype becomes amorphous at a uniaxial strain s = 0.23 (0.22) and with a maximum stress of 168 (151) GPa. In both cases, the amorphous state is the consequence of structural collapse associated with the bending of the three-atom chain. Careful analysis of the structures after amorphization shows that the B{sub 11}C and B{sub 12} icosahedra are highly distorted but still identifiable. Calculations of the elastic coefficients (C{sub ij}) at different uniaxial strains indicate that both polytypes may collapse under a much smaller shear strain (stress) than the uniaxial strain (stress). On the other hand, separate simulations of both models under hydrostatic compression up to a pressure of 180 GPa show no signs of amorphization, in agreement with experimental observation. The amorphized nature of both models is confirmed by detailed analysis of the evolution of the radial pair distribution function, total density of states, and distribution of effective charges on atoms. The electronic structure and bonding of the boron carbide structures before and after amorphization are calculated to further elucidate the mechanism of amorphization and to help form the proper rationalization of experimental observations.

  16. Detailed Chemical Kinetic Reaction Mechanisms for Autoignition of Isomers of Heptane Under Rapid Compression

    SciTech Connect

    Westbrook, C K; Pitz, W J; Boercker, J E; Curran, H J; Griffiths, J F; Mohamed, C; Ribaucour, M

    2001-12-17

    Detailed chemical kinetic reaction mechanisms are developed for combustion of all nine isomers of heptane (C{sub 7}H{sub 16}), and these mechanisms are tested by simulating autoignition of each isomer under rapid compression machine conditions. The reaction mechanisms focus on the manner in which the molecular structure of each isomer determines the rates and product distributions of possible classes of reactions. The reaction pathways emphasize the importance of alkylperoxy radical isomerizations and addition reactions of molecular oxygen to alkyl and hydroperoxyalkyl radicals. A new reaction group has been added to past models, in which hydroperoxyalkyl radicals that originated with abstraction of an H atom from a tertiary site in the parent heptane molecule are assigned new reaction sequences involving additional internal H atom abstractions not previously allowed. This process accelerates autoignition in fuels with tertiary C-H bonds in the parent fuel. In addition, the rates of hydroperoxyalkylperoxy radical isomerization reactions have all been reduced so that they are now equal to rates of analogous alkylperoxy radical isomerizations, significantly improving agreement between computed and experimental ignition delay times in the rapid compression machine. Computed ignition delay times agree well with experimental results in the few cases where experiments have been carried out for specific heptane isomers, and predictive model calculations are reported for the remaining isomers. The computed results fall into three general groups; the first consists of the most reactive isomers, including n-heptane, 2-methyl hexane and 3-methyl hexane. The second group consists of the least reactive isomers, including 2,2-dimethyl pentane, 3,3-dimethyl pentane, 2,3-dimethyl pentane, 2,4-dimethyl pentane and 2,2,3-trimethyl butane. The remaining isomer, 3-ethyl pentane, was observed computationally to have an intermediate level of reactivity. These observations are generally

  17. Oil point and mechanical behaviour of oil palm kernels in linear compression

    NASA Astrophysics Data System (ADS)

    Kabutey, Abraham; Herak, David; Choteborsky, Rostislav; Mizera, Čestmír; Sigalingging, Riswanti; Akangbe, Olaosebikan Layi

    2017-07-01

    The study described the oil point and mechanical properties of roasted and unroasted bulk oil palm kernels under compression loading. The literature information available is very limited. A universal compression testing machine and vessel diameter of 60 mm with a plunger were used by applying maximum force of 100 kN and speed ranging from 5 to 25 mm min-1. The initial pressing height of the bulk kernels was measured at 40 mm. The oil point was determined by a litmus test for each deformation level of 5, 10, 15, 20, and 25 mm at a minimum speed of 5 mmmin-1. The measured parameters were the deformation, deformation energy, oil yield, oil point strain and oil point pressure. Clearly, the roasted bulk kernels required less deformation energy compared to the unroasted kernels for recovering the kernel oil. However, both kernels were not permanently deformed. The average oil point strain was determined at 0.57. The study is an essential contribution to pursuing innovative methods for processing palm kernel oil in rural areas of developing countries.

  18. Electrical, mechanical and morphological properties of compressed carbon felt electrodes in vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Chang, Tien-Chan; Zhang, Jun-Pu; Fuh, Yiin-Kuen

    2014-01-01

    Experiments including electrical, mechanical and morphological aspects under compression in the range of 0-40% have been carried out on four potential materials for liquid diffusion layer (LDL) of vanadium redox flow battery (VRB) (including three widely used carbon felt and one recently utilized metal foam) in order to better understand the influence of the fundamental properties on the battery performance. We experimentally demonstrate that the electrical contact resistance is predominately determined by the clamping force. It is observed that increasing the stress applied on the carbon felt, which is of high interest for the durability of the membrane electrode assembly (MEA), has moreover a positive effect on their performance due to the reduced contact resistance. However, a simultaneously reduced porosity is also recorded and possibly detrimental to the mass transport of vanadium electrolyte. Moreover, the intrusion of carbon felts under compression is also characterized. Experimental results show that with the clamping force increases, both the porosity of the carbon felts underneath the rib and channel volume decrease, and this can be mainly attributed to the deformation of the carbon felts and resultant changed of the void volume as well as intrusion.

  19. A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting.

    PubMed

    Li, Xiaotian; Guo, Mingsen; Dong, Shuxiang

    2011-04-01

    A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 κΩ, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz. © 2011 IEEE

  20. Vertebrae in compression: Mechanical behavior of arches and centra in the gray smooth-hound shark (Mustelus californicus).

    PubMed

    Porter, Marianne E; Long, John H

    2010-03-01

    In swimming sharks, vertebrae are subjected, in part, to compressive loads as axial muscles contract. We currently have no information about which vertebral elements, centra, arch cartilages, or both, actually bear compressive loads in cartilaginous vertebrae. To address this issue, the goal of this experiment was to determine the load-bearing ability of arch and centrum cartilages in compression, to determine the material properties of shark vertebrae, and to document fracture patterns in the centra with and without the arches. Intact vertebrae and vertebrae with the arch cartilages experimentally removed (centra alone) were subjected to compressive loading to failure at a single strain rate. The maximum compressive forces sustained by the vertebrae and the centra are statistically indistinguishable. Thus we conclude that under these testing conditions the arch does not bear appreciable loads. Independent evidence for this conclusion comes from the fact that vertebrae fail in compression at the centra, and not at the arches. Overall, the results of these mechanical tests suggest that the neural arches are not the primary load-bearing structure during axial compression.

  1. Failure analysis of porcupine quills under axial compression reveals their mechanical response during buckling.

    PubMed

    Torres, Fernando G; Troncoso, Omar P; Diaz, John; Arce, Diego

    2014-11-01

    Porcupine quills are natural structures formed by a thin walled conical shell and an inner foam core. Axial compression tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR) were all used to compare the characteristics and mechanical properties of porcupine quills with and without core. The failure mechanisms that occur during buckling were analyzed by scanning electron microscopy (SEM), and it was found that delamination buckling is mostly responsible for the decrease in the measured buckling stress of the quills with regard to predicted theoretical values. Our analysis also confirmed that the foam core works as an energy dissipater improving the mechanical response of an empty cylindrical shell, retarding the onset of buckling as well as producing a step wise decrease in force after buckling, instead of an instantaneous decrease in force typical for specimens without core. Cell collapse and cell densification in the inner foam core were identified as the key mechanisms that allow for energy absorption during buckling.

  2. Deformation mechanism of basic rock during long-term compression: Area of HLW repository design, Chelyabinsk District, Russia

    SciTech Connect

    Petrov, V.A.; Zviagintsev, L.I.; Poluektov, V.V.

    1996-08-01

    A combination of ultrasound, mechanical and petrographic results for long-term experimental compression of greenschist facies porphyritic andesite tuffs indicate a deformation mechanism that depends upon the mineral composition, textural-structural features of the rocks and the orientation of compression relative to the rock textures. Three dry samples of rock were investigated. Coaxial compression of a massive sample for 816 hours and a foliated sample for 1,176 hours (pressure orthogonal to foliation) is characterized by solidification when the rocks are temporarily metastable. Compressive strength of the first sample is 850 kg/cm{sup 2} and of the second one, 800 kg/cm{sup 2}. Experimentally, the rock behavior changes from a plastic to a brittle regime of deformation. In contrast, compression of the foliated sample parallel to foliation causes disintegration along the foliation within 480 hours without solidification. The rock is liable to brittle deformation and its compressive strength is 500 kg/cm{sup 2}. These results may have implications for characterization of near-field processes in connection with numerous subhorizontal zones of schistosity within the strata that are targeted for underground disposal of high-level wastes (HLW) in the Mayak radiochemical complex area.

  3. Transforming powder mechanical properties by core/shell structure: compressible sand.

    PubMed

    Shi, Limin; Sun, Changquan Calvin

    2010-11-01

    Some active pharmaceutical ingredients possess poor mechanical properties and are not suitable for tableting. Using fine sand (silicon dioxide), we show that a core/shell structure, where a core particle (sand) is coated with a thin layer of polyvinylpyrrolidone (PVP), can profoundly improve powder compaction properties. Sand coated with 5% PVP could be compressed into intact tablets. Under a given compaction pressure, tablet tensile strength increases dramatically with the amount of coating. This is in sharp contrast to poor compaction properties of physical mixtures, where intact tablets cannot be made when PVP content is 20% or less. The profoundly improved tabletability of core/shell particles is attributed to the formation of a continuous three-dimensional bonding network in the tablet. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association

  4. Computer-aided study of the mechanical behavior of the jaw bone fragments under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Kolmakova, Tatyana V.

    2016-08-01

    The article presents the calculated results of the mechanical behavior of simulative bone mesovolumes under uniaxial compression with their architectonics corresponding to the human jaw bone fragments. The results of the calculation show that changes in the structure and mineral content of the bone fragments can lead to the change of their prevailing deformation response. New effective parameters were introduced to reflect the character of the distribution of stresses and strains in the bone mesovolumes. Implants are to be created and selected to correspond to the offered parameters and longitudinal modulus of elasticity of bone mesovolumes in order to maintain the stress and strain state existing in bone macrovolume during the implantation and in order to avoid bone restructuring through its borderline resorption.

  5. Compression strength failure mechanisms in unidirectional composite laminates containing a hole

    NASA Technical Reports Server (NTRS)

    Johnson, Eric R.

    1993-01-01

    Experiments on graphite-epoxy laminated plates containing unloaded small holes show that these laminates are notch insensitive. That is, the uniaxial strength of these laminates with small holes exceeds the strength predicted by a point stress criterion using the stress concentration factor for the in-plane stress field. Laminates containing large holes exhibit notch sensitive behavior and consequently their strength is reasonably well predicted by the stress concentration effect. This hole size effect is manifested both in tension and in compression. Apparently, some mechanism must cause in-plane stress relief for laminates containing small holes. The purpose of this research was to study the influence of geometric nonlinearity on the micromechanical response of a filamentary composite material in the presence of a strain gradient caused by a discontinuity such as a hole. A mathematical model was developed at the micromechanical level to investigate this geometrically nonlinear effect.

  6. Biomechanical analysis of the mechanism of elbow fracture-dislocations by compression force.

    PubMed

    Wake, Hirofumi; Hashizume, Hiroyuki; Nishida, Keiichiro; Inoue, Hajime; Nagayama, Noriyuki

    2004-01-01

    Fracture-dislocations of the coronoid and olecranon were produced experimentally, and their onset mechanisms were analyzed to clarify the effects of compression force on the coronoid and olecranon. The study used two-dimensional finite element method (2D-FEM) simulations and static loading experiments. The latter applied axial force distally to 40 cadaveric elbows. Posterior fracture-dislocations occurred between 15 degrees of extension and 30 degrees of flexion, anterior or posterior fracture-dislocations at 60 degrees, and only anterior fracture-dislocations at 90 degrees. Injuries were mainly to anterior or posterior support structures. The 2D-FEM simulations showed that the stress concentration areas moved from the coronoid process to the olecranon as position changed from extension to flexion. The very high frequency of concurrent fracture-dislocations of radial head or neck in the current study indicated that the radial head may also function as a stabilizer in the anterior support system.

  7. First principles calculation of the mechanical compression of two organic molecular crystals.

    PubMed

    Zerilli, Frank J; Kuklja, Maija M

    2006-04-20

    The mechanical compression curves for the organic molecular crystals 1,1-diamino-2,2-dinitroethylene and beta-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (beta-HMX) are calculated using the Hartree-Fock approximation to the solutions of the many-body Schrödinger equation for a periodic system as implemented in the computer program CRYSTAL. No correction was made for basis set superposition error. The equilibrium lattice parameters are reproduced to within 1% of reported experimental values. Pressure values on the isotherm also agree well with reported experimental values. To obtain accurate results, the relaxation of all the atomic coordinates as well as the lattice parameters under a fixed volume constraint was required.

  8. Blunt chest trauma.

    PubMed

    Adegboye, V O; Ladipo, J K; Brimmo, I A; Adebo, A O

    2002-12-01

    A retrospective study was conducted at the cardiothoracic surgical unit of the University College Hospital, Ibadan on all consecutive, blunt chest injury patients treated between May 1975 and April 1999. The period of study was divided into 2 periods: May 1975-April 1987, May 1987-April 1999. The aim was to determine the pattern of injury, the management and complications of the injury among the treated. Blunt chest trauma patients were 69% (1331 patients) of all chest injury patients (1928 patients) treated. Mean age for the 2 periods was 38.3 +/- 15 years and 56.4 +/- 6.2 years, the male:female ratio was 4:1 and 2:1 respectively. The incidence of blunt chest trauma tripled in the second period. Blunt chest trauma was classified as involving bony chest wall or without the involvement of bony chest wall. Majority of the blunt chest injuries were minor chest wall injuries (68%, 905 patients), 7.6% (101 patients) had major but stable chest wall injuries, 10.8% (144 patients) had flail chest injuries. Thoracic injuries without fractures of bony chest wall occurred in 181 patients (13.6%). Seven hundred and eighty-seven patients (59.1%) had associated extra-thoracic injuries, in 426 patients (54.1%) two or more extra-thoracic systems were involved. While orthopaedic injury was the most frequent extra-thoracic injury (69.5%) associated with blunt chest trauma, craniospinal injury (31.9%) was more common injury among the patients with severe or life threatening chest trauma. The most common extra-thoracic operation was laparotomy (221 patients). Nine hundred and seventy patients (72.9%) had either closed thoracostomy drainage or clinical observation, 361 patients (27.1%) had major thoracic surgical intervention (emergent in 134 patients, late in 227 patients). Most of the severe lung contusion that needed ventilatory care (85 patients) featured among patients with bony chest wall injury, 15 were without chest wall injury. Majority of patients 63.2% (835 patients) had no

  9. Fibrous dysplasia of the rib presenting as a huge chest wall tumor: report of a case.

    PubMed

    Chang, B S; Lee, S C; Harn, H J

    1994-07-01

    Fibrous dysplasia of the rib is not uncommon, but is rarely demonstrated as a huge chest wall mass with severe clinical symptoms. A 59-year-old patient, presenting with a huge, rapidly expanding chest wall tumor compressing the lung, liver and heart accompanied by chest pain and dyspnea, is reported. The tumor was success-fully excised by local radical resection.

  10. Scaling laws and deformation mechanisms of nanoporous copper under adiabatic uniaxial strain compression

    SciTech Connect

    Yuan, Fuping Wu, Xiaolei

    2014-12-15

    A series of large-scale molecular dynamics simulations were conducted to investigate the scaling laws and the related atomistic deformation mechanisms of Cu monocrystal samples containing randomly placed nanovoids under adiabatic uniaxial strain compression. At onset of yielding, plastic deformation is accommodated by dislocations emitted from void surfaces as shear loops. The collapse of voids are observed by continuous emissions of dislocations from void surfaces and their interactions with further plastic deformation. The simulation results also suggest that the effect modulus, the yield stress and the energy aborption density of samples under uniaxial strain are linearly proportional to the relative density ρ. Moreover, the yield stress, the average flow stress and the energy aborption density of samples with the same relative density show a strong dependence on the void diameter d, expressed by exponential relations with decay coefficients much higher than -1/2. The corresponding atomistic mechanisms for scaling laws of the relative density and the void diameter were also presented. The present results should provide insights for understanding deformation mechanisms of nanoporous metals under extreme conditions.

  11. [Intrathoracic drainage of a compressive pulmonary bulla in a patient receiving mechanical ventilation].

    PubMed

    Sleth, J C; Aldebert, S; Safont, L; Knoerr, M F

    1998-01-01

    A lung suppuration may result in a lung bulla with its own course. We report such a case following a Pseudomonas aeruginosa pneumonia of the upper right lobe, after aspiration of gastric contents, in a 21-year-old tracheotomized patient in chronic post-traumatic coma. Mechanical ventilation (IPPV) was indicated because of respiratory insufficiency. The pneumonia was followed by an abscess and later a lung bulla, increasing in size under the effect of mechanical ventilation with progressive mediastinal compression. Surgery was contraindicated because of poor physical status. An acute episode of cardiac tamponade was controlled with an emergency transthoracic drain insertion into the bulla. The course was favourable after a drainage for 23 days and a persisting small cavity in the lung apex. All weaning attempts being unsuccessful, the patient was discharged under home mechanical ventilation. A CT-scan control 6 months later showed a normal lung parenchyma. The various alternative techniques to surgery for treatment of a lung bulla are discussed.

  12. Scaling laws and deformation mechanisms of nanoporous copper under adiabatic uniaxial strain compression

    NASA Astrophysics Data System (ADS)

    Yuan, Fuping; Wu, Xiaolei

    2014-12-01

    A series of large-scale molecular dynamics simulations were conducted to investigate the scaling laws and the related atomistic deformation mechanisms of Cu monocrystal samples containing randomly placed nanovoids under adiabatic uniaxial strain compression. At onset of yielding, plastic deformation is accommodated by dislocations emitted from void surfaces as shear loops. The collapse of voids are observed by continuous emissions of dislocations from void surfaces and their interactions with further plastic deformation. The simulation results also suggest that the effect modulus, the yield stress and the energy aborption density of samples under uniaxial strain are linearly proportional to the relative density ρ. Moreover, the yield stress, the average flow stress and the energy aborption density of samples with the same relative density show a strong dependence on the void diameter d, expressed by exponential relations with decay coefficients much higher than -1/2. The corresponding atomistic mechanisms for scaling laws of the relative density and the void diameter were also presented. The present results should provide insights for understanding deformation mechanisms of nanoporous metals under extreme conditions.

  13. Dynamic Compression Effects on Immature Nucleus Pulposus: a Study Using a Novel Intelligent and Mechanically Active Bioreactor

    PubMed Central

    Li, Pei; Gan, Yibo; Wang, Haoming; Zhang, Chengmin; Wang, Liyuan; Xu, Yuan; Song, Lei; Li, Songtao; Li, Sukai; Ou, Yangbin; Zhou, Qiang

    2016-01-01

    Background: Previous cell culture and animal in vivo studies indicate the obvious effects of mechanical compression on disc cell biology. However, the effects of dynamic compression magnitude, frequency and duration on the immature nucleus pulposus (NP) from an organ-cultured disc are not well understood. Objective: To investigate the effects of a relatively wide range of compressive magnitudes, frequencies and durations on cell apoptosis and matrix composition within the immature NP using an intelligent and mechanically active bioreactor. Methods: Discs from the immature porcine were cultured in a mechanically active bioreactor for 7 days. The discs in various compressive magnitude groups (0.1, 0.2, 0.4, 0.8 and 1.3 MPa at a frequency of 1.0 Hz for 2 hours), frequency groups (0.1, 0.5, 1.0, 3.0 and 5.0 Hz at a magnitude of 0.4 MPa for 2 hours) and duration groups (1, 2, 4 and 8 hours at a magnitude of 0.4 MPa and frequency of 1.0 Hz) experienced dynamic compression once per day. Discs cultured without compression were used as controls. Immature NP samples were analyzed using the TUNEL assay, histological staining, glycosaminoglycan (GAG) content measurement, real-time PCR and collagen II immunohistochemical staining. Results: In the 1.3 MPa, 5.0 Hz and 8 hour groups, the immature NP showed a significantly increase in apoptotic cells, a catabolic gene expression profile with down-regulated matrix molecules and up-regulated matrix degradation enzymes, and decreased GAG content and collagen II deposition. In the other compressive magnitude, frequency and duration groups, the immature NP showed a healthier status regarding NP cell apoptosis, gene expression profile and matrix production. Conclusion: Cell apoptosis and matrix composition within the immature NP were compressive magnitude-, frequency- and duration-dependent. The relatively high compressive magnitude or frequency and long compressive duration are not helpful for maintaining the healthy status of an

  14. Mechanical compression insults induce nanoscale changes of membrane-skeleton arrangement which could cause apoptosis and necrosis in dorsal root ganglion neurons.

    PubMed

    Quan, Xin; Guo, Kai; Wang, Yuqing; Huang, Liangliang; Chen, Beiyu; Ye, Zhengxu; Luo, Zhuojing

    2014-01-01

    In a primary spinal cord injury, the amount of mechanical compression insult that the neurons experience is one of the most critical factors in determining the extent of the injury. The ultrastructural changes that neurons undergo when subjected to mechanical compression are largely unknown. In the present study, using a compression-driven instrument that can simulate mechanical compression insult, we applied mechanical compression stimulation at 0.3, 0.5, and 0.7 MPa to dorsal root ganglion (DRG) neurons for 10 min. Combined with atomic force microscopy, we investigated nanoscale changes in the membrane-skeleton, cytoskeleton alterations, and apoptosis induced by mechanical compression injury. The results indicated that mechanical compression injury leads to rearrangement of the membrane-skeleton compared with the control group. In addition, mechanical compression stimulation induced apoptosis and necrosis and also changed the distribution of the cytoskeleton in DRG neurons. Thus, the membrane-skeleton may play an important role in the response to mechanical insults in DRG neurons. Moreover, sudden insults caused by high mechanical compression, which is most likely conducted by the membrane-skeleton, may induce necrosis, apoptosis, and cytoskeletal alterations.

  15. Gallium Arsenate Dihydrate under Pressure: Elastic Properties, Compression Mechanism, and Hydrogen Bonding.

    PubMed

    Spencer, Elinor C; Soghomonian, Victoria; Ross, Nancy L

    2015-08-03

    Gallium arsenate dihydrate is a member of a class of isostructural compounds, with the general formula M(3+)AsO4·2H2O (M(3+) = Fe, Al, In, or Ga), which are being considered as potential solid-state storage media for the sequestration of toxic arsenic cations. We report the first high-pressure structural analysis of a metal arsenate dihydrate, namely, GaAsO4·2H2O. This compound crystallizes in the orthorhombic space group Pbca with Z = 8. Accurate unit cell parameters as a function of pressure were obtained by high-pressure single-crystal X-ray diffraction, and a bulk modulus of 51.1(3) GPa for GaAsO4·2H2O was determined from a third-order Birch-Murnaghan equation of state fit to the P-V data. Assessment of the pressure dependencies of the unit cell lengths showed that the compressibility of the structure along the axial directions increases in the order of [010] < [100] < [001]. This order was found to correlate well with the proposed compression mechanism for GaAsO4·2H2O, which involves deformation of the internal channel void spaces of the polyhedral helices that lie parallel to the [010] direction, and increased distortion of the GaO6 octahedra. The findings of the high-pressure diffraction experiment were further supported by the results from variable-pressure Raman analysis of GaAsO4·2H2O. Moreover, we propose a revised and more complex model for the hydrogen-bonding scheme in GaAsO4·2H2O, and on the basis of this revision, we reassigned the peaks in the OH stretching regions of previously published Raman spectra of this compound.

  16. Energy efficient of ethanol recovery in pervaporation membrane bioreactor with mechanical vapor compression eliminating the cold traps.

    PubMed

    Fan, Senqing; Xiao, Zeyi; Li, Minghai

    2016-07-01

    An energy efficient pervaporation membrane bioreactor with mechanical vapor compression was developed for ethanol recovery during the process of fermentation coupled with pervaporation. Part of the permeate vapor at the membrane downstream under the vacuum condition was condensed by running water at the first condenser and the non-condensed vapor enriched with ethanol was compressed to the atmospheric pressure and pumped into the second condenser, where the vapor was easily condensed into a liquid by air. Three runs of fermentation-pervaporation experiment have been carried out lasting for 192h, 264h and 360h respectively. Complete vapor recovery validated the novel pervaporation membrane bioreactor. The total flux of the polydimethylsiloxane (PDMS) membrane was in the range of 350gm(-2)h(-1) and 600gm(-2)h(-1). Compared with the traditional cold traps condensation, mechanical vapor compression behaved a dominant energy saving feature.

  17. Chest physiotherapy effectiveness to reduce hospitalization and mechanical ventilation length of stay, pulmonary infection rate and mortality in ICU patients.

    PubMed

    Castro, Antonio A M; Calil, Suleima Ramos; Freitas, Súsi Andréa; Oliveira, Alexandre B; Porto, Elias Ferreira

    2013-01-01

    Although physiotherapy is an integral part of the multiprofessional team in most ICUs there is only limited evidence concerning the effectiveness of its procedures. The objectives of this study were to verify if physiotherapy care provided within 24 h/day for hospitalized patients in the ICU reduce the length of stay, mechanical ventilation support, pulmonary infection and mortality compared to a physiotherapy care provided within 6 h/day. A cohort study was designed to assess differences between one hospital where patients were given physiotherapy care for 24 h/day and another hospital with only 6 h/day. We considered the following as outcome measurements: clinical diagnosis, medication in use, presence of associated diseases, APACHE II and SOFA scores, ICU and mechanical ventilation length of stay, development of pulmonary infections and survival. One hundred and forty-six patients were enrolled. Patients admitted in the service A presented a lower length of stay in mechanical ventilation (p < 0.0001), ICU stay (p = 0.0003), respiratory infections (p = 0.0043) than patients admitted in service B. No difference was found for APACHE II score (p = 0.8) and SOFA scores (p = 0.2) between groups. The mortality risk was OR 1.3 (1.01-2.33) (p = 0.04) for patients in the service B. The presence of a physiotherapist in the intensive care unit contributes decisively to the early recovery of the patient, reducing mechanical ventilation support need, number of hospitalization days, incidence of respiratory infection and risk of mortality. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. NiTi and NiTi-TiC composites. Part 2: Compressive mechanical properties

    SciTech Connect

    Fukami-Ushiro, K.L.; Mari, D.; Dunand, D.C.

    1996-01-01

    The deformation behavior under uniaxial compression of NiTi containing 0, 10, and 20 vol pct TiC particulates is investigated both below and above the matrix martensitic transformation temperature: (1) at room temperature, where the martensitic matrix deforms plastically by slip and/or twinning; and (2) at elevated temperature, where plastic deformation of the austenitic matrix takes place by slip and/or formation of stress-induced martensite. The effect of TiC particles on the stress-strain curves of the composites depends upon which of these deformation mechanisms is dominant. First, in the low-strain elastic region, the mismatch between the stiff, elastic particles and the elastic-plastic matrix is relaxed in the composites: (1) by twinning of the martensitic matrix; and (2) by dislocation slip of the austenitic matrix. Second, in the moderate-strain plastic region where nonslip deformation mechanisms are dominant, mismatch dislocations stabilize the matrix for all samples, thus (1) reducing the extent of twinning in the martensitic samples or (2) reducing the formation of stress-induced martensite in the austenitic samples. This leads to a strengthening of the composites, similar to the strain-hardening effect observed in metal matrix composites deforming solely by slip. Third, in the high-strain region controlled by dislocation slip, weakening of the NiTi composites results, because the matrix contains (1) untwinned martensite or (2) retained austenite, which exhibit lower slip yield stress than twinned or stress-induced martensite, respectively.

  19. The mechanical behaviour of synthetic, poorly consolidated granular rock under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Saidi, F.; Bernabé, Y.; Reuschlé, T.

    2003-07-01

    In order to isolate the effect of grain size and cementation on the mechanical behaviour of poorly consolidated granular rock, we prepared synthetic rock samples in which these two parameters were varied independently. Various proportions of sand, Portland cement and water were mixed and cast in a mold. The mixture was left pressure-free during curing, thus ensuring that the final material was poorly consolidated. We used two natural well-sorted sands with grain sizes of 0.22 and 0.8 mm. The samples were mechanically tested in a uniaxial press. Static Young's modulus was measured during the tests by performing small stress excursions at discrete intervals along the stress-strain curves. All the samples exhibited nonlinear elasticity, i.e., Young's modulus increased with stress. As expected, we found that the uniaxial compressive strength increased with increasing cement content. Furthermore, we observed a transition from grain size sensitivity of strength at cement content less than 20-30% to grain size independence above this value. The measured values of Young's modulus are well explained by models based on rigid inclusions embedded in a soft matrix, at high cement content, and on cemented grain-to-grain contacts, at low cement content. Both models predict grain size independence in well-sorted cemented sands. The observed grain size sensitivity at low cement content is probably due to microstructural differences between fine- and coarse-grained materials caused by small differences in grain sorting quality.

  20. Dynamic mechanical response of magnesium single crystal under compression loading: Experiments, model, and simulations

    NASA Astrophysics Data System (ADS)

    Li, Qizhen

    2011-05-01

    Magnesium single crystal samples are compressed at room temperature under quasistatic (˜0.001 s-1) loading in a universal testing machine and dynamic (430, 1000, and 1200 s-1) loading in a split Hopkinson pressure bar system. Stress-strain curves show that (a) the fracture strain slightly increases with the strain rate; and (b) the maximum strength and strain hardening rate increase significantly when the testing changes from quasistatic to dynamic, although they do not vary much when the strain rate for dynamic testing varies in the range of 430-1200 s-1. The operation of the secondary pyramidal slip system is the dominating deformation mechanism, which leads to a fracture surface with an angle of ˜42° with respect to the loading axial direction. A theoretical material model based on Johnson-Cook law is also derived. The model includes the strain hardening and strain rate hardening terms, and provides the stress-strain relations matching with the experimental results. Finite element simulations for the strain rates used in the experiments predict the mechanical responses of the material that agree well with the experimental data.

  1. Axially compressed buckling of an embedded boron nitride nanotube subjected to thermo-electro-mechanical loadings

    NASA Astrophysics Data System (ADS)

    Salehi-Khojin, Amin; Jalili, Nader

    2007-04-01

    Unlike widely-used carbon nanotubes, boron nitride nanotubes (BNNTs) have shown to possess stable semiconducting behavior and strong piezoelectricity. Such properties along with their outstanding mechanical properties and thermal conductivity, make BNNTs promising candidate reinforcement materials for a verity of applications especially nanoelectronic and nanophotonic devices. Motivated by these abilities, we aim to study the buckling behavior of BNNT-reinforced piezoelectric polymeric composites when subjected to combined electro-thermo-mechanical loadings. For this, the multi-walled structure of BNNT is considered as elastic media and a set of concentric cylindrical shell with van der Waals interaction between them. Using three-dimensional equilibrium equations, Donnell shell theory is utilized to show that the axially compressive resistance of BNNT varies with applying thermal and electrical loads. The effect of BNNT piezoelectric property on the buckling behavior of the composites is demonstrated. More specifically, it is shown that applying direct and reverse voltages to BNNT changes the buckling loads for any axial and circumferential wavenumbers. Such capability could be uniquely utilized when designing BNNT-reinforced composites.

  2. Mechanical characterisation of hydrogels using Brillouin microscopy, ultrasound and unconfined compression tests (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wu, Pei-Jung; Kabakova, Irina V.; Song, ChengZe; Paterson, Carl; Overby, Darryl R.; Török, Peter

    2017-02-01

    Mechanical characterisation of biomaterials provides the basis for investigating disease-related changes in the biomechanical properties of living tissues and cells. Brillouin microscopy offers a non-invasive and label-free method to measure material properties. Briefly, Brillouin scattering involves energy exchange between photons and acoustic phonons, resulting in an optical frequency shift of the scattered light. This shift is proportional to the speed of sound in the material, and consequently to the longitudinal elastic modulus (M). However, it is unclear how Brillouin measurements, which characterize the mechanical response at GHz frequencies, relate to mechanical properties measured at much lower frequencies ( 1 Hz) relevant to physiological conditions. Furthermore, as most biomaterials are hydrated, it remains unclear how the relative incompressibility of water influences the acoustic wave speed so as to affect Brillouin measurements of hydrated biomaterials. In this study, we aim to establish the relationship between Brillouin frequency shift, acoustic wave speed and quasi-static elastic modulus of hydrogels of varying stiffness. Hydrogels are homogeneous and isotropic materials that mimic the poroelastic nature of biological tissues. Each measurement probes the mechanics of hydrogels in a significantly different frequency range: GHz for Brillouin imaging, MHz for ultrasound and Hz for unconfined compression tests. The acoustic wave speed falls into range from 1490 to 1533 m/s in both MHz (ultrasound) and GHz (Brillouin) frequency ranges. The quasi-static modulus correlates positively with Brillouin frequency shift, increasing from 6 to 54 kPa. All the results indicate the measurements obtained by Brillouin microscopy are capable of representing the material properties of hydrogels in quasi-static condition.

  3. Chest Wall Trauma.

    PubMed

    Majercik, Sarah; Pieracci, Fredric M

    2017-05-01

    Chest wall trauma is common, and contributes significantly to morbidity and mortality of trauma patients. Early identification of major chest wall and concomitant intrathoracic injuries is critical. Generalized management of multiple rib fractures and flail chest consists of adequate pain control (including locoregional modalities); management of pulmonary dysfunction by invasive and noninvasive means; and, in some cases, surgical fixation. Multiple studies have shown that patients with flail chest have substantial benefit (decreased ventilator and intensive care unit days, improved pulmonary function, and improved long-term functional outcome) when they undergo surgery compared with nonoperative management. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. [Chest pain in adolescents].

    PubMed

    Raiola, G; Galati, M C; De Sanctis, V; Salerno, D; Arcuri, V M; Mussari, A

    2002-12-01

    In children and in adolescents, chest pain is relatively common and self-limiting. The close association between chest pain, cardiopathies and sudden death is the cause of intense anxiety in boys and their parents and even doctors. The most frequent causes of chest pain, the diagnosis and the eventual treatment are examined. Finally, the causes of chest pain due to drug abuse (in particular cocaine) and to CO poisoning are also examined. Good knowledge of the problem, an accurate anamnesis and a careful objective exam are useful to choose the most suitable treatment.

  5. Bacteria associated with acute exacerbations of chronic obstructive pulmonary disease requiring mechanical ventilation and antimicrobial management in Respiratory Care Unit of Central Chest Institute of Thailand.

    PubMed

    Siripataravanit, Sudarat; Phaicharoen, Ransiya; Termsetcharoen, Sumol; Klangprapun, Nuchchara

    2012-08-01

    To investigate the role of bacterial infection, antimicrobial sensitivity and antibiotics usage in severe acute exacerbations of COPD requiring mechanical ventilation in the respiratory care unit of the central chest institute of Thailand. All data were analyzed from medical records of 38 patients admitted in RCU of CCIT during 1 November 2008-31 August 2011 with severe acute exacerbations of COPD requiring mechanical ventilation. The tracheobronchial aspirates specimens were collected for Gram stain, quantitative culture and sensitivities testing. The sera were tested for antibodies to Chlamydophila pneumoniae and Mycoplasma pneumoniae with the immunofluorescence test. Bacterial pathogens were isolated by quantitative culture from 18 of 38 patients (47.3%). Gram-negative bacilli were the predominant organisms. K. pneumoniae was the predominant isolates 7 cases (18.4%) followed by H. influenzae 3 cases and P. aeruginosa 3 cases (7.9% each). A single pathogen was isolated from 12 patients (31.6%), two pathogens were isolated from 5 patients (13.2%) and three pathogens from 1 patient (2.6%). Serological samples were positive for Chlamydophila pneumoniae in 5 (13.2%) cases. 1 of these patients had coinfection with Acinetobacter baumannii. In the RCU, 33 (86.8%) patients were empirically treated with antibiotic. Ceftriaxone was the most commonly used antibiotic. 57.8% (22/38 cases) of the patients with severe exacerbations in COPD requiring mechanical ventilation caused by bacterial infection, Gram-negative bacilli were the predominant organism with a resistance to commonly used antibiotics of K. pneumoniae, P. aeruginosa, S. aureus, E. coli, A. baumannii, P. mirabilis, S. dysgalactiae and S. pneumoniae. 13.2% of the patients had serological evidence of Chlamydophila pneumoniae infection.

  6. Reconstruction of chest wall defects.

    PubMed

    Hasse, J

    1991-12-01

    A series of 61 consecutive procedures of chest wall resection and reconstruction in 58 patients during the period between August, 1986 and December, 1990 is reported. The ages ranged between 6-77 years. The chest wall resection was indicated for malignant affections in 54 cases. Among these, there were 24 patients with bronchial carcinoma invading the chest wall, 17 patients with primary or metastatic sarcoma, 11 patients with recurrent breast cancer and 3 with cancer metastases of varying origin. Pulmonary resection included pneumonectomy in 8 cases, lobectomy in 19, segmental and wedge resections in 26. In the majority of resections, the reconstruction was accomplished without implants. In cases with full thickness removal of the chest wall, the plane of the rib cage and/or the sternum was reconstructed using Vicryl mesh (n = 7), PTFE soft tissue patch (n = 11), marlex-mesh (n = 1), or methyl-methacrylate (n = 3). There was one case of hospital mortality, 6 weeks postoperatively, due to neurological failure from an independent preoperatively undiagnosed brain tumor. There were 4 reoperations: one early and one late (4 months) infection, one case of limited superficial necrosis of a flap and one with chronic lymphous drainage from a large myocutaneous flap. In no instance was primary postoperative ventilation therapy necessary. Mechanical ventilation was instituted only on day 8 in the patient who accounts for the mortality in this series. In the presence of primary infection, the greater omentum was used for the restoration of the integument.

  7. Mechanical behavior of twinned SiC nanowires under combined tension-torsion and compression-torsion strain

    SciTech Connect

    Li, Zhijie; Wang, Shengjie; Wang, Zhiguo; Zu, Xiaotao T.; Gao, Fei; Weber, William J.

    2010-07-01

    The mechanical behavior of twinned silicon carbide (SiC) nanowires under combined tension-torsion and compression-torsion is investigated using molecular dynamics simulations with an empirical potential. The simulation results show that both the tensile failure stress and buckling stress decrease under combined tension-torsional and combined compression-torsional strain, and they decrease with increasing torsional rate under combined loading. The torsion rate has no effect on the elastic properties of the twinned SiC nanowires. The collapse of the twinned nanowires takes place in a twin stacking fault of the nanowires.

  8. [Chest wall mesenchymal hamartoma: a case report].

    PubMed

    Morales, Olga Lucía; Valencia, María de la Luz; Gómez, Carolina; Pérez, María del Pilar; Sanín, Emilio; Vásquez, Luz Marina

    2010-01-01

    Chest wall mesenchymal hamartoma is an extremely rare benign tumor. Approximately 80 cases have been reported in the literature. Most tumors are manifested at birth with a painless palpable mass of the chest wall, usually unilateral. Respiratory symptoms result from extrinsic compression of the pulmonary parenchyma, and the severity of the symptoms will depend on the size and location of the lesion. Imaging features are characteristic, but definitive diagnosis is histological. Herein, a case is described of a four month old infant with diagnosis of chest wall mesenchymal hamartoma, manifested at birth. Different treatment options are described, including expectations from tumor management, the possibility of spontaneous regression, and the morbidity associated with the surgical option.

  9. Mechanical Properties of PZT 52/48 under Shock and Ramp Wave Compression

    NASA Astrophysics Data System (ADS)

    Wise, J. L.; Montgomery, S. T.; Jackson, D. P.; Clark, G. E.; Duckett, E. B.

    2011-06-01

    Complementary gas-gun and electromagnetic pulse experiments have yielded data regarding the dynamic mechanical behavior for poled and unpoled specimens of a PZT (52 wt% lead zirconate plus 48 wt% lead titanate) ferroelectric ceramic subjected to shock and intermediate-strain-rate ramp wave (i . e . , quasi-isentropic) loading. For each experiment, velocity interferometer (VISAR) diagnostics provided time-resolved measurements of sample response for conditions nominally involving one-dimensional (i . e . , uniaxial strain) compression and release. Wave profiles obtained during the shock experiments have been analyzed to assess the Hugoniot Elastic Limit (HEL), Hugoniot equation of state, spall strength, and high-pressure yield strength of PZT. Profiles from the ramp wave experiments have been processed to determine the locus of isentropic stress-strain states generated in PZT for deformation rates substantially lower than those associated with shock loading. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  10. Atomistic modeling of structure II gas hydrate mechanics: Compressibility and equations of state

    NASA Astrophysics Data System (ADS)

    Vlasic, Thomas M.; Servio, Phillip; Rey, Alejandro D.

    2016-08-01

    This work uses density functional theory (DFT) to investigate the poorly characterized structure II gas hydrates, for various guests (empty, propane, butane, ethane-methane, propane-methane), at the atomistic scale to determine key structure and mechanical properties such as equilibrium lattice volume and bulk modulus. Several equations of state (EOS) for solids (Murnaghan, Birch-Murnaghan, Vinet, Liu) were fitted to energy-volume curves resulting from structure optimization simulations. These EOS, which can be used to characterize the compressional behaviour of gas hydrates, were evaluated in terms of their robustness. The three-parameter Vinet EOS was found to perform just as well if not better than the four-parameter Liu EOS, over the pressure range in this study. As expected, the Murnaghan EOS proved to be the least robust. Furthermore, the equilibrium lattice volumes were found to increase with guest size, with double-guest hydrates showing a larger increase than single-guest hydrates, which has significant implications for the widely used van der Waals and Platteeuw thermodynamic model for gas hydrates. Also, hydrogen bonds prove to be the most likely factor contributing to the resistance of gas hydrates to compression; bulk modulus was found to increase linearly with hydrogen bond density, resulting in a relationship that could be used predictively to determine the bulk modulus of various structure II gas hydrates. Taken together, these results fill a long existing gap in the material chemical physics of these important clathrates.

  11. Atomistic modeling of structure II gas hydrate mechanics: Compressibility and equations of state

    SciTech Connect

    Vlasic, Thomas M.; Servio, Phillip; Rey, Alejandro D.

    2016-08-15

    This work uses density functional theory (DFT) to investigate the poorly characterized structure II gas hydrates, for various guests (empty, propane, butane, ethane-methane, propane-methane), at the atomistic scale to determine key structure and mechanical properties such as equilibrium lattice volume and bulk modulus. Several equations of state (EOS) for solids (Murnaghan, Birch-Murnaghan, Vinet, Liu) were fitted to energy-volume curves resulting from structure optimization simulations. These EOS, which can be used to characterize the compressional behaviour of gas hydrates, were evaluated in terms of their robustness. The three-parameter Vinet EOS was found to perform just as well if not better than the four-parameter Liu EOS, over the pressure range in this study. As expected, the Murnaghan EOS proved to be the least robust. Furthermore, the equilibrium lattice volumes were found to increase with guest size, with double-guest hydrates showing a larger increase than single-guest hydrates, which has significant implications for the widely used van der Waals and Platteeuw thermodynamic model for gas hydrates. Also, hydrogen bonds prove to be the most likely factor contributing to the resistance of gas hydrates to compression; bulk modulus was found to increase linearly with hydrogen bond density, resulting in a relationship that could be used predictively to determine the bulk modulus of various structure II gas hydrates. Taken together, these results fill a long existing gap in the material chemical physics of these important clathrates.

  12. Strain softening mechanism at meso scale during micro-compression in an ultrafine-grained pure copper

    SciTech Connect

    Xu, Jie; Li, Jianwei; Shan, Debin; Guo, Bin

    2015-09-15

    Strain softening behavior has been found at meso scale using micro-compression testing in an ultrafine-grained (UFG) pure copper by comparison with the typical strain hardening in conventional coarse-grained (CG) material. Microstructural observations show that grain size remains nearly the same including the fraction of high-angle grain boundaries during micro-compression in UFG pure copper. The Kernel average misorientation(KAM) distribution measured by electron backscatter diffraction (EBSD), as a statistical method, is applied to qualitatively evaluate dislocation density in the interior of the grains. It is suggested that the deformation mechanisms are dominated by grain boundary sliding and grain rotation accompanied by dislocation slip in UFG pure copper, which demonstrates that the strain softening behavior is primarily caused by dislocation annihilation during micro-compression.

  13. Effects of number of ply, compression temperature, pressure and time on mechanical properties of prepreg kenaf-polypropilene composites

    NASA Astrophysics Data System (ADS)

    Tomo, H. S. S.; Ujianto, O.; Rizal, R.; Pratama, Y.

    2017-07-01

    Composite material thermoplastic was prepared from polypropilen granule as matrix, kenaf fiber as reinforcement and grafted polypropylene copolymer maleic anhydride as coupling agent. Composite products were produced as sandwich structures using compression molding. This research aimed to observe the influence of number of ply, temperature, pressure, and compression time using factorial design. Effects of variables on tensile and flexural strength were analyzed. Experimental results showed that tensile and flexural strength were influenced by degradation, fiber compaction, and matrix - fiber interaction mechanisms. Flexural strength was significantly affected by number of ply and its interaction to another process parameters (temperature, pressure, and compression time), but no significant effect of process parameters on tensile strength. The highest tensile strength (62.0 MPa) was produced at 3 ply, 210 °C, 50 Bar, and 3 min compression time (low, high, high, low), while the highest flexural strength (80.3 MPa) was produced at 3 ply, 190 °C, 50 Bar, and 3 min compression time (low, low, high, low).

  14. Compressive mechanical of high strength concrete (HSC) after different high temperature history

    NASA Astrophysics Data System (ADS)

    Zhao, Dongfu; Liu, Yuchen; Gao, Haijing; Han, Xiao

    2017-08-01

    The compression strength test of high strength concrete under different high-temperature conditions was carried out by universal testing machine. The friction surface of the pressure bearing surface of the specimen was composed of three layers of plastic film and glycerol. The high temperature working conditions were the combination of different heating temperature and different constant temperature time. The characteristics of failure modes and the developments of cracks were observed; the residual compressive strength and stress-strain curves were measured; the effect of different temperature and heating time on the strength and deformation of high strength concrete under uniaxial compression were analyzed; the failure criterion formula of the high strength concrete after high temperature under uniaxial compression was established. The formula of the residual compressive strength of high strength concrete under the influence of heating temperature and constant temperature time was put forward. The relationship between the residual elastic modulus and the peak strain and residual compressive strength of high strength concrete and different high temperature conditions is established. The quantitative relationship that the residual compressive strength decreases the residual elastic modulus decreases and the peak strain increases with the increase of heating temperature and the constant temperature time was given, which provides a reference for the detection and evaluation of high strength concrete structures after fire.

  15. Effects of Compressive Force, Particle Size and Moisture Content on Mechanical Properties of Biomass Grinds

    SciTech Connect

    Mani, Sudhagar; Tabil, Lope Jr.; Sokhansanj, Shahabaddine

    2006-03-01

    Chemical composition, moisture content, bulk and particle densities, and geometric mean particle size were determined to characterize grinds from wheat and barley straws, corn stover and switchgrass. The biomass grinds were compressed for five levels of compressive forces (1000, 2000, 3000, 4000, 4400 N) and three levels of particle sizes (3.2, 1.6 and 0.8 mm) at two levels of moisture contents (12% and 15% (wb) to establish the compression and relaxation data. Corn stover grind produced the highest compact density at low pressure during compression. Compressive force, particle size and moisture content of grinds significantly affected the compact density of barley straw, corn stover and switchgrass grinds. However, different particle sizes of wheat straw grind did not produce any significant difference on compact density. Barley straw grind had the highest asymptotic modulus among all other biomass grinds indicating that compact from barley straw grind were more rigid than those of other compacts. Asymptotic modulus increased with an increase in maximum compressive pressure. The trend of increase in asymptotic modulus (EA) with the maximum compressive pressure ( 0) was fitted to a second order polynomial equation. Keywords: Biomass grinds, chemical composition, compact density and asymptotic modulus

  16. Prevalence and mechanism of triazole resistance in Aspergillus fumigatus in a referral chest hospital in Delhi, India and an update of the situation in Asia

    PubMed Central

    Chowdhary, Anuradha; Sharma, Cheshta; Kathuria, Shallu; Hagen, Ferry; Meis, Jacques F.

    2015-01-01

    Aspergillus fumigatus causes varied clinical syndromes ranging from colonization to deep infections. The mainstay of therapy of Aspergillus diseases is triazoles but several studies globally highlighted variable prevalence of triazole resistance, which hampers the management of aspergillosis. We studied the prevalence of resistance in clinical A. fumigatus isolates during 4 years in a referral Chest Hospital in Delhi, India and reviewed the scenario in Asia and the Middle East. Aspergillus species (n = 2117) were screened with selective plates for azole resistance. The isolates included 45.4% A. flavus, followed by 32.4% A. fumigatus, 15.6% Aspergillus species and 6.6% A. terreus. Azole resistance was found in only 12 (1.7%) A. fumigatus isolates. These triazole resistant A. fumigatus (TRAF) isolates were subjected to (a) calmodulin and β tubulin gene sequencing (b) in vitro antifungal susceptibility testing against triazoles using CLSI M38-A2 (c) sequencing of cyp51A gene and real-time PCR assay for detection of mutations and (d) microsatellite typing of the resistant isolates. TRAF harbored TR34/L98H mutation in 10 (83.3%) isolates with a pan-azole resistant phenotype. Among the remaining two TRAF isolates, one had G54E and the other had three non-synonymous point mutations. The majority of patients were diagnosed as invasive aspergillosis followed by allergic bronchopulmonary aspergillosis and chronic pulmonary aspergillosis. The Indian TR34/L98H isolates had a unique genotype and were distinct from the Chinese, Middle East, and European TR34/L98H strains. This resistance mechanism has been linked to the use of fungicide azoles in agricultural practices in Europe as it has been mainly reported from azole naïve patients. Reports published from Asia demonstrate the same environmental resistance mechanism in A. fumigatus isolates from two highly populated countries in Asia, i.e., China and India and also from the neighboring Middle East. PMID:26005442

  17. Traumatic asphyxia due to blunt chest trauma: a case report and literature review

    PubMed Central

    2012-01-01

    Introduction Crush asphyxia is different from positional asphyxia, as respiratory compromise in the latter is caused by splinting of the chest and/or diaphragm, thus preventing normal chest expansion. There are only a few cases or small case series of crush asphyxia in the literature, reporting usually poor outcomes. Case presentation We present the case of a 44-year-old Caucasian man who developed traumatic asphyxia with severe thoracic injury and mild brain edema after being crushed under heavy auto vehicle mechanical parts. He remained unconscious for an unknown time. The treatment included oropharyngeal intubation and mechanical ventilation, bilateral chest tube thoracostomies, treatment of brain edema and other supportive measures. Our patient’s outcome was good. Traumatic asphyxia is generally under-reported and most authors apply supportive measures, while the final outcome seems to be dependent on the length of time of the chest compression and on the associated injuries. Conclusion Treatment for traumatic asphyxia is mainly supportive with special attention to the re-establishment of adequate oxygenation and perfusion; treatment of the concomitant injuries might also affect the final outcome. PMID:22935547

  18. Evaluation of an injectable hydrogel and polymethyl methacrylate in restoring mechanics to compressively fractured spine motion segments.

    PubMed

    Balkovec, Christian; Vernengo, Andrea J; Stevenson, Peter; McGill, Stuart M

    2016-11-01

    Compressive fracture can produce profound changes to the mechanical profile of a spine segment. Minimally invasive repair has the potential to restore both function and structural integrity to an injured spine. Use of both hydrogels to address changes to the disc, combined with polymethyl methacrylate (PMMA) to address changes to the vertebral body, has the potential to facilitate repair. The purpose of this investigation was to determine if the combined use of hydrogel injection and PMMA could restore the mechanical profile of an axially injured spinal motion segment. This is a basic science study evaluating a combination of hydrogel injection and vertebroplasty on restoring mechanics to compressively injured porcine spine motion segments. Fourteen porcine spine motion segments were subject to axial compression until fracture using a dynamic servohydraulic testing apparatus. Rotational and compressive stiffness was measured for each specimen under the following conditions: initial undamaged, fractured, fatigue loading under compression, hydrogel injection, PMMA injection, and fatigue loading under compression. Group 1 received hydrogel injection followed by PMMA injection, whereas Group 2 received PMMA injection followed by hydrogel injection. This study was funded under a Natural Sciences and Engineering Research Council of Canada discovery grant. PMMA injection was found to alter the compressive stiffness properties of axially injured spine motion segments, restoring values from Groups 1 and 2 to 89.3%±29.3% and 81%±27.9% of initial values respectively. Hydrogel injection was found to alter the rotational stiffness properties, restoring specimens in Groups 1 and 2 to 151.5%±81% and 177.2%±54.9% of initial values respectively. Prolonged restoration of function was not possible, however, after further fatigue loading. Using this repair technique, replication of the mechanism of injury appears to cause a rapid deterioration in function of the motion segments

  19. A new soil mechanics approach to quantify and predict land subsidence by peat compression

    NASA Astrophysics Data System (ADS)

    Koster, Kay; Erkens, Gilles; Zwanenburg, Cor

    2016-10-01

    Land subsidence threatens many coastal areas. Quantifying current and predicting future subsidence are essential to sustain the viability of these areas with respect to rising sea levels. Despite its scale and severity, methods to quantify subsidence are scarce. In peat-rich subsidence hot spots, subsidence is often caused by peat compression. We introduce the standard Cone Penetration Test (CPT) as a technique to quantify subsidence due to compression of peat. In a test in the Holland coastal plain, the Netherlands, we found a strong relationship between thickness reduction of peat and cone resistance, due to an increase in peat stiffness after compression. We use these results to quantify subsidence of peat in subsiding areas of Sacramento-San Joaquin delta and Kalimantan, and found values corresponding with previously made observations. These results open the door for CPT as a new method to document past and predict future subsidence due to peat compression over large areas.

  20. METABOLIC EFFECTS OF ANGULATION, COMPRESSION AND REDUCED MOBILITY ON ANNULUS FIBROSIS IN A MODEL OF ALTERED MECHANICAL ENVIRONMENT IN SCOLIOSIS

    PubMed Central

    Stokes, Ian A.F.; McBride, Carole; Aronsson, David D.; Roughley, Peter J.

    2013-01-01

    Study Design Comparison of disc tissue from rat tails in six groups having different mechanical conditions imposed. Objectives To identify disc annulus changes associated with the supposed altered biomechanical environment in a spine with scoliosis deformity using an immature rat model that produces disc narrowing and wedging. Background Intervertebral discs become wedged and narrowed in a scoliosis curve, probably due in part to altered biomechanical environment. Methods Tail discs of 5-week-old immature Sprague-Dawley rats were subjected to an altered mechanical environment using an external apparatus applying permutations of loading and deformity for 5 weeks. Four groups of rats (A) 15 degrees Angulation, (B) Angulation with 0.1 MPa Compression, (C) 0.1 MPa Compression, and (R) Reduced mobility, together with a sham and a control group were studied. Disc height changes and matrix composition (water, DNA, GAG and HA content) were measured after 5 weeks, and proline and sulphate incorporation and mRNA expression were measured at 5 days and 5 weeks. Results After 5 weeks, disc space was significantly narrowed relative to internal controls in all four intervention groups. Water content and cellularity (DNA content) were not different at interventional levels relative to internal controls and not different between the concave and convex sides of the angulated discs. There was increased GAG content in compressed tissue (in Groups B and C), as expected, and compression resulted in a decrease in hyaluronic acid size. Slightly increased incorporation of tritiated-proline into the concave side of angulated discs and compressed discs was observed. Asymmetries of gene expression in Groups A and B, and some group-wise differences, did not identify consistent patterns associating the discs’ responses to mechanical alterations. Conclusions Intervertebral discs in this model underwent substantial narrowing after 5 weeks, with minimal alteration in tissue composition and

  1. Hydrogen effect on compression mechanical properties of TiNb alloys at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Losertová, M.; Štefek, O.; Schindler, I.; Szkandera, L.; Kudela, P.

    2017-02-01

    The study of this work was focused on the hydrogen effect on hot deformation behavior of hydrogen charged TiNb based alloys at three temperatures in comparison with non-charged specimens. The Ti24Nb and Ti26Nb (at.%) alloys were heat treated by three step regime in argon or hydrogen atmospheres. The hot compression tests were performed on a Gleeble 3800 machine at 800, 750 and 700°C with compression strain of 5×10-3 s-1 and deformation degree of 50 %. The microstructure resulting from heat treatment as well as from isothermal compression test was analyzed using optical and scanning electron microscopies. Measurement of microhardness revealed that higher microhardness values for Ti24Nb after thermo-hydrogen treatment corresponded to fine grained microstructure and strengthening by grain boundaries. Hydrogen contents determined using LECO RH600 analyzer showed that Ti26Nb contained higher amount of hydrogen due to the stabilization of beta phase by higher Nb concentration. Based on the hot compression test results, the plasticity at elevated temperatures was evaluated. The evolution of uniaxial compressive test curves showed the stabilization of flow stress due to the hydrogen for high deformations at lower temperatures. The differences in hot compression behavior for both niobium contents on the one hand and for hydrogen charged and non-charged specimens on the other hand were observed.

  2. Micro-Mechanical Analysis About Kink Band in Carbon Fiber/Epoxy Composites Under Longitudinal Compression

    NASA Astrophysics Data System (ADS)

    Zhang, Mi; Guan, Zhidong; Wang, Xiaodong; Du, Shanyi

    2016-12-01

    Kink band is a typical phenomenon for composites under longitudinal compression. In this paper, theoretical analysis and finite element simulation were conducted to analyze kink angle as well as compressive strength of composites. Kink angle was considered to be an important character throughout longitudinal compression process. Three factors including plastic matrix, initial fiber misalignment and rotation due to loading were considered for theoretical analysis. Besides, the relationship between kink angle and fiber volume fraction was improved and optimized by theoretical derivation. In addition, finite element models considering fiber stochastic strength and Drucker-Prager constitutive model for matrix were conducted in ABAQUS to analyze kink band formation process, which corresponded with the experimental results. Through simulation, the loading and failure procedure can be evidently divided into three stages: elastic stage, softening stage, and fiber break stage. It also shows that kink band is a result of fiber misalignment and plastic matrix. Different values of initial fiber misalignment angle, wavelength and fiber volume fraction were considered to explore the effects on compressive strength and kink angle. Results show that compressive strength increases with the decreasing of initial fiber misalignment angle, the decreasing of initial fiber misalignment wavelength and the increasing of fiber volume fraction, while kink angle decreases in these situations. Orthogonal array in statistics was also built to distinguish the effect degree of these factors. It indicates that initial fiber misalignment angle has the largest impact on compressive strength and kink angle.

  3. Solid-extracellular fluid interaction and damage in the mechanical response of rat brain tissue under confined compression.

    PubMed

    Haslach, Henry W; Leahy, Lauren N; Riley, Peter; Gullapalli, Rao; Xu, Su; Hsieh, Adam H

    2014-01-01

    The mechanical processes that underlie mild traumatic brain injury from physical insults are not well understood. One aspect in particular that has not been examined is the tissue fluid, which is known to be critical in the mechanical function of other organs. To investigate the contributions of solid-fluid interactions to brain tissue mechanics, we performed confined compression tests, that force the extracellular fluid (ECF) to flow in the direction of the deformation, on 6.35mm diameter, 3mm long cylindrical samples excised from various regions of rat brains. Two types of tests in deformation control, (1) quasi-static, slow and moderate constant strain rate tests at 0.64×10(-5)/s, 0.001/s and 1/s to large strains and (2) several applications of slow linear deformation to 5% strain each followed by stress relaxation are employed to explore the solid-fluid interaction. At slow and moderate compressive strain rates, we observed stress peaks in the applied strain range at about 11%, whose magnitudes exhibited statistically significant dependence on strain rate. These data suggest that the ECF carries load until the tissue is sufficiently damaged to permit pathological fluid flow. Under the slow ramp rate in the ramp-relaxation cycles protocol, commonly used to estimate permeability, the stress relaxes to zero after the first cycle, rather than to a non-zero equilibrium stress corresponding to the applied strain, which further implicates mechanical damage. Magnetic resonance imaging (MRI) of changes in tissue microstructure during confined compression, before and after compression, provides further evidence of tissue damage. The solid-fluid interactions, reflected in the morphology of the stress-stretch curves and supported by the MRI data, suggest that increases in hydrostatic pressure in the ECF may contribute to mechanical damage of brain tissue. © 2013 Elsevier Ltd. All rights reserved.

  4. Mechanical Failure Begins Preferentially Near Resorption Cavities in Human Vertebral Cancellous Bone Under Compression

    PubMed Central

    Slyfield, C.R.; Tkachenko, E.V.; Fischer, S.E.; Ehlert, K.M.; Yi, I. H.; Jekir, M. G.; O’Brien, R. G.; Keaveny, T.M.; Hernandez, C.J.

    2012-01-01

    Summary The amount of bone turnover in the body has been implicated as a factor that can influence fracture risk and bone strength. Here we test the idea that remodeling cavities promote local tissue failure by determining if microscopic tissue damage (microdamage) caused by controlled loading in vitro is more likely to form near resorption cavities. Specimens of human vertebral cancellous bone (L4, 7 male and 2 female, age 70 ± 10, mean ± SD) were loaded in compression to the yield point, stained for microscopic tissue damage and submitted to three-dimensional fluorescent imaging using serial milling (image voxel size 0.7 × 0.7 × 5.0 µm). We found the resulting damage volume per bone volume (DV/BV) was correlated with percent eroded surface (p < 0.01, r2 = 0.65), demonstrating that whole specimen measures of resorption cavities and microdamage are related. Locations of microdamage were more than two times as likely to have a neighboring resorption cavity than randomly selected sites without microdamage (relative risk 2.39, 95% confidence interval of relative risk: 2.09 – 2.73), indicating a spatial association between resorption cavities and microdamage at the local level. Individual microdamage sites were 48,700 (40,100; 62,700) µm3 in size (median, 25th and 75th percentiles). That microdamage was associated with resorption cavities when measured at the whole specimen level as well as at the local level provides strong evidence that resorption cavities play a role in mechanical failure processes of cancellous bone and therefore have the potential to influence resistance to clinical fracture. PMID:22426306

  5. Mechanical properties and shear failure surfaces of two alumina powders in triaxial compression

    SciTech Connect

    ZEUCH,DAVID H.; GRAZIER,J. MARK; ARGUELLO JR.,JOSE G.; EWSUK,KEVIN G.

    2000-04-24

    In the manufacture of ceramic components, near-net-shape parts are commonly formed by uniaxially pressing granulated powders in rigid dies. Density gradients that are introduced into a powder compact during press-forming often increase the cost of manufacturing, and can degrade the performance and reliability of the finished part. Finite element method (FEM) modeling can be used to predict powder compaction response, and can provide insight into the causes of density gradients in green powder compacts; however, accurate numerical simulations require accurate material properties and realistic constitutive laws. To support an effort to implement an advanced cap plasticity model within the finite element framework to realistically simulate powder compaction, the authors have undertaken a project to directly measure as many of the requisite powder properties for modeling as possible. A soil mechanics approach has been refined and used to measure the pressure dependent properties of ceramic powders up to 68.9 MPa (10,000 psi). Due to the large strains associated with compacting low bulk density ceramic powders, a two-stage process was developed to accurately determine the pressure-density relationship of a ceramic powder in hydrostatic compression, and the properties of that same powder compact under deviatoric loading at the same specific pressures. Using this approach, the seven parameters that are required for application of a modified Drucker-Prager cap plasticity model were determined directly. The details of the experimental techniques used to obtain the modeling parameters and the results for two different granulated alumina powders are presented.

  6. Mechanical effects of high density polyethylene dynamic compression plate hole inserts on bone-plate constructs.

    PubMed

    Sullivan, E K; Nunamaker, D M; Richardson, D W

    2005-01-01

    This study was conducted in order to investigate the mechanical effects of high density polyethylene screw hole inserts in 4.5 mm Dynamic Compression Plate (DCP)--synthetic bone constructs. A mid-shaft 'osteotomy' was created in synthetic bone cylinders. The bisecting 'osteotomy' was reduced using six-hole broad DCPs and 4.5 mm cortical bone screws. The screws adjacent to the 'osteotomy' were placed using a load-guide. The remaining screws were placed in neutral position. High density polyethylene DCP screw hole inserts were incorporated with each screw in neutral position, in the experimental group. The bone plate constructs were tested in four point cyclical bending with the plates loaded at 2,000 Newtons, for a total of 6,000 cycles. Osteotomy gap was measured at 3,000 and 6,000 cycles. Screw head deflection adjacent to the osteotomy was measured. Kruskal-Wallis non-parametric testing was used for statistical comparisons. There was significantly less gapping at the osteotomy site in the treatment group after 3,000 cycles (0.49 +/- 0.18 mm [control] vs. 0.06 +/- 0.14 mm [treated], P=0.02) and 6,000 cycles (0.6 +/- 0.18 mm [control] vs. 0.1 +/- 0.22 mm [treated], P=0.02). The screws adjacent to the gap were significantly more deformed in the control group than those in the treated constructs (3.63 +/- 1.81 [control] vs. 1.06 +/- 1.55 [treated], P=0.0002). The polyethylene inserts improved the interface between bone plate and screw head, resulting in decreased relative movement of the implant and bone. The polyethylene inserts also resulted in less bending of the loaded screws.

  7. Enhanced Compressive Strength of Nanostructured Aluminum Reinforced with SiC Nanoparticles and Investigation of Strengthening Mechanisms and Fracture Behavior

    NASA Astrophysics Data System (ADS)

    Akbarpour, M. R.; Torknik, F. S.; Manafi, S. A.

    2017-08-01

    In this study, microstructure and mechanical properties of nanostructured Al and Al reinforced with different volume fractions of SiC nanoparticles fabricated through a powder metallurgy route, including high-energy mechanical milling and hot pressing method, were examined. Nanostructured Al and the Al-8 vol.%SiC nanocomposite showed superior compressive strength of ≈300 and ≈412 MPa, respectively, with reasonable ductility. The high strength of the nanocomposite was attributed to the reduced grain size of the Al matrix and homogeneous dispersion of the nanoparticles in the matrix. The effects of nanoparticles on strengthening of Al and fracture mechanisms are presented and discussed.

  8. Mechanical Cardiopulmonary Resuscitation In and On the Way to the Cardiac Catheterization Laboratory.

    PubMed

    William, Preethi; Rao, Prashant; Kanakadandi, Uday B; Asencio, Alejandro; Kern, Karl B

    2016-05-25

    Cardiac arrest, though not common during coronary angiography, is increasingly occurring in the catheterization laboratory because of the expanding complexity of percutaneous interventions (PCI) and the patient population being treated. Manual chest compression in the cath lab is not easily performed, often interrupted, and can result in the provider experiencing excessive radiation exposure. Mechanical cardiopulmonary resuscitation (CPR) provides unique advantages over manual performance of chest compression for treating cardiac arrest in the cardiac cath lab. Such advantages include the potential for uninterrupted chest compressions, less radiation exposure, better quality chest compressions, and less crowded conditions around the catheterization table, allowing more attention to ongoing PCI efforts during CPR. Out-of-hospital cardiac arrest patients not responding to standard ACLS therapy can be transported to the hospital while mechanical CPR is being performed to provide safe and continuous chest compressions en route. Once at the hospital, advanced circulatory support can be instituted during ongoing mechanical CPR. This article summarizes the epidemiology, pathophysiology and nature of cardiac arrest in the cardiac cath lab and discusses the mechanics of CPR and defibrillation in that setting. It also reviews the various types of mechanical CPR and their potential roles in and on the way to the laboratory. (Circ J 2016; 80: 1292-1299).

  9. Mechanical properties of nanocrystalline metals, intermetalics and multiphase materials determined by tension, compression and disk-bend techniques

    SciTech Connect

    Eastman, J.A.; Thompson, L.J.; DiMelfi, R.J.; Choudry, M. Dollar, M.; Weertman, J.R.; Rittner, M.N.; Youngdahl, C.J. /

    1997-02-01

    The mechanical behavior of nanocrystalline metallic, intermetallic, and multiphase materials was investigated using tension, compression, and disk-bend techniques. Nanocrystalline NiAl, Al-Al{sub 3}Zr, and Cu were synthesized by gas condensation and either resistive or electron beam heating followed by high temperature vacuum compaction. Disk- bend tests of nanocrystalline NiAl show evidence of improved ductility at room temperature in this normally extremely brittle material. In contrast, tension tests of multiphase nanocrystalline Al- Al{sub 3}Zr samples show significant increases in strength by substantial reductions in ductility with decreasing grain size. Compression tests of nanocrystalline copper result in substantially higher yield stress and total elongation values than those measured in tensile tests. Implications for operative deformation mechanisms in these materials are discussed.

  10. Cell-like pressure sensors reveal increase of mechanical stress towards the core of multicellular spheroids under compression

    PubMed Central

    Dolega, M. E.; Delarue, M.; Ingremeau, F.; Prost, J.; Delon, A.; Cappello, G.

    2017-01-01

    The surrounding microenvironment limits tumour expansion, imposing a compressive stress on the tumour, but little is known how pressure propagates inside the tumour. Here we present non-destructive cell-like microsensors to locally quantify mechanical stress distribution in three-dimensional tissue. Our sensors are polyacrylamide microbeads of well-defined elasticity, size and surface coating to enable internalization within the cellular environment. By isotropically compressing multicellular spheroids (MCS), which are spherical aggregates of cells mimicking a tumour, we show that the pressure is transmitted in a non-trivial manner inside the MCS, with a pressure rise towards the core. This observed pressure profile is explained by the anisotropic arrangement of cells and our results suggest that such anisotropy alone is sufficient to explain the pressure rise inside MCS composed of a single cell type. Furthermore, such pressure distribution suggests a direct link between increased mechanical stress and previously observed lack of proliferation within the spheroids core. PMID:28128198

  11. The Protective Effects of Salubrinal on the Cartilage and Subchondral Bone of the Temporomandibular Joint under Various Compressive Mechanical Stimulations

    PubMed Central

    Zhang, Caixia; Chen, Sheng; Li, Huang

    2016-01-01

    Excessive mechanical loads on the temporomandibular joint (TMJ) can cause mandibular cartilage degradation and subchondral bone erosion, but the treatment of these conditions remains challenging. Salubrinal, which target eukaryotic translation initiation factor 2 alpha, has been shown to have multiple beneficial effects on skeletal tissue. Here, we examined the effect of a Salubrinal injection on the mandibular cartilage and subchondral bone of the TMJ under various compressive stresses. We conducted in vivo analyses in rat models using various compressive stresses (40 g and 80 g), and we observed time-related degeneration and pathological changes in the cartilage and subchondral bone of the TMJ at days 1, 3 and 7 through histological measurements, subcellular observation, and changes in proliferation and apoptosis. After the Salubrinal injection, the thickness of the cartilage recovered, and the pathological change was alleviated. In the Salubrinal/light (Sal/light) compressive stress group, the drug altered the proliferation and apoptosis of chondrocytes most significantly at day 1. In the Salubrinal/heavy (Sal/heavy) compressive stress group, the drug increased the proliferation of chondrocytes most significantly at day 1 and reduced the apoptosis of chondrocytes most significantly at day 7. Salubrinal also increased the area of the bone trabeculae and suppressed inflammatory responses and pathological change in the subchondral bone of the TMJ. Together, these results indicate that the administration of Salubrinal reduces apoptosis and strengthens the proliferation of chondrocyte to varying degrees at days 1, 3 and 7 under various compressive mechanical stresses, both of which contribute to the recovery of cartilage thickness and the alleviation of pathological change. Salubrinal also suppresses inflammatory responses and pathological change in the subchondral bone of the TMJ. PMID:27196267

  12. Hypoventilation: neuromuscular and chest wall disorders.

    PubMed

    Goldstein, R S

    1992-09-01

    Patients with neuromuscular and chest wall disorders are vulnerable at night when alterations in ventilatory mechanics and control associated with their disease are imposed on the changes in mechanics and control associated with sleep. The physiologic and clinical consequences of these events may be reversed by nocturnal mechanical ventilatory support.

  13. Experimental approach and modelling of the mechanical behaviour of graphite fuel elements subjected to compression pulses

    NASA Astrophysics Data System (ADS)

    Forquin, P.

    2010-06-01

    Among the activities led by the Generation IV International Forum (GIF) relative to the future nuclear systems, the improvement of recycling of fuel elements and their components is a major issue. One of the studied systems by the GIF is the graphite-moderated high-temperature gas cooled reactor (HTGR). The fuel elements are composed of fuel roads half-inch in diameter named compacts. The compacts contain spherical particles made of actinide kernels about 500 m in diameter coated with three layers of carbon and silicon carbide, each about 50 m thick, dispersed in a graphite matrix. Recycling of compacts requires first a separation of triso-particles from the graphite matrix and secondly, the separation of the triso-coating from the kernels. This aim may be achieved by using pulsed currents: the compacts are placed within a cell filled by water and exposed to high voltage between 200 - 500 kV and discharge currents from 10 to 20 kA during short laps of time (about 2 µs) [1-2]. This repeated treatment leads to a progressive fragmentation of the graphite matrix and a disassembly of the compacts. In order to improve understanding of the fragmentation properties of compacts a series of quasi-static and dynamic experiments have been conducted with similar cylindrical samples containing 10% (volume fraction) of SiC particles coated in a graphite matrix. First, quasi-static compression tests have been performed to identify the mechanical behaviour of the material at low strain-rates (Fig.1). The experiments reveal a complex elasto-visco-plastic behaviour before a brittle failure. The mechanical response is characterised by a low yield stress (about 1 MPa), a strong strain-hardening in the loading phase and marked hysteresis-loops during unloading-reloading stages. Brittle failure is observed for axial stress about 13 MPa. In parallel, a series of flexural tests have been performed with the aim to characterise the quasi-static tensile strength of the particulate

  14. Comparative study of mechanical properties of dental restorative materials and dental hard tissues in compressive loads

    PubMed Central

    Lee, Jong Yeop

    2014-01-01

    There are two objectives. One is to show the differences in the mechanical properties of various dental restorative materials compared to those of enamel and dentin. The other is to ascertain which dental restorative materials are more suitable for clinical treatments. Amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy were processed as dental restorative material specimens. The specimens (width, height, and length of 1.2, 1.2, and 3.0 mm, respectively) were compressed at a constant loading speed of 0.1 mm/min. The maximum stress (115.0 ± 40.6, 55.0 ± 24.8, 291.2 ± 45.3, 274.6 ± 52.2, 2206.0 ± 522.9, and 953.4 ± 132.1 MPa), maximum strain (7.8% ± 0.5%, 4.0% ± 0.1%, 12.7% ± 0.8%, 32.8% ± 0.5%, 63.5% ± 14.0%, and 45.3% ± 7.4%), and elastic modulus (1437.5 ± 507.2, 1548.4 ± 583.5, 2323.4 ± 322.4, 833.1 ± 92.4, 3895.2 ± 202.9, and 2222.7 ± 277.6 MPa) were evident for amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy, respectively. The reference hardness value of amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy was 90, 420, 130–135, 86.6–124.2, 1250, and 349, respectively. Since enamel grinds food, its abrasion resistance is important. Therefore, hardness value should be prioritized for enamel. Since dentin absorbs bite forces, mechanical properties should be prioritized for dentin. The results suggest that gold alloy simultaneously has a hardness value lower than enamel (74.8 ± 18.1), which is important in the wear of the opposing natural teeth, and higher maximum stress, maximum strain, and elastic modulus than dentin (193.7 ± 30.6 MPa, 11.9% ± 0.1%, 1653.7 ± 277.9 MPa, respectively), which are important considering the rigidity to absorb bite forces. PMID:25352921

  15. Topic 1.1.2, Unsteady Aerodynamics: Time-Varying Compressible Dynamic Stall Mechanisms Due to Freestream Mach Oscillations

    DTIC Science & Technology

    2014-12-31

    YOUR FORM TO THE ABOVE ADDRESS. Ohio State University 1960 Kenny Road Columbus , OH 43210 -1016 30-Sep-2014 ABSTRACT Number of Papers published in peer...Jensen, Christopher D., Gregory, James W., Gompertz, Kyle A., Bons, Jeffrey P.. Compressible Dynamic Stall Mechanisms Due to Airfoil Pitching and...Characteristics of a NACA 0015 Airfoil,” Data Report, Aeronautical and Astronautical Research Laboratory, Ohio State University, Columbus , Ohio. Hird, K

  16. Chest Pain: First Aid

    MedlinePlus

    ... condition. Seek emergency medical assistance immediately. Pneumonia with pleurisy Frequent signs and symptoms of pneumonia are chest ... a breath or coughing. This condition is called pleurisy. One sign of pleurisy is that the pain ...

  17. Chest CT Scan

    MedlinePlus

    ... inside the scanner. For some diagnoses, a contrast dye, often iodine-based, may be injected into a ... your arm before the imaging test. This contrast dye highlights areas inside your chest and creates clearer ...

  18. Chest tube insertion - slideshow

    MedlinePlus

    ... Health Topics Chest Injuries and Disorders Collapsed Lung Critical Care Lung Diseases Pleural Disorders A.D.A. ... Duplication for commercial use must be authorized in writing by ADAM Health Solutions. About MedlinePlus Site Map ...

  19. Induced sensitivity of Bacillus subtilis colony morphology to mechanical media compression

    PubMed Central

    Polka, Jessica K.

    2014-01-01

    Bacteria from several taxa, including Kurthia zopfii, Myxococcus xanthus, and Bacillus mycoides, have been reported to align growth of their colonies to small features on the surface of solid media, including anisotropies created by compression. While the function of this phenomenon is unclear, it may help organisms navigate on solid phases, such as soil. The origin of this behavior is also unknown: it may be biological (that is, dependent on components that sense the environment and regulate growth accordingly) or merely physical. Here we show that B. subtilis, an organism that typically does not respond to media compression, can be induced to do so with two simple and synergistic perturbations: a mutation that maintains cells in the swarming (chained) state, and the addition of EDTA to the growth media, which further increases chain length. EDTA apparently increases chain length by inducing defects in cell separation, as the treatment has only marginal effects on the length of individual cells. These results lead us to three conclusions. First, the wealth of genetic tools available to B. subtilis will provide a new, tractable chassis for engineering compression sensitive organisms. Second, the sensitivity of colony morphology to media compression in Bacillus can be modulated by altering a simple physical property of rod-shaped cells. And third, colony morphology under compression holds promise as a rapid, simple, and low-cost way to screen for changes in the length of rod-shaped cells or chains thereof. PMID:25289183

  20. Hydro-mechanical behavior of Municipal Solid Waste subject to leachate recirculation in a large-scale compression reactor cell

    SciTech Connect

    Olivier, Franck . E-mail: franck.olivier@ujf-grenoble.fr; Gourc, Jean-Pierre . E-mail: gourc@ujf-grenoble.fr

    2007-07-01

    The paper presents the results of a laboratory experiment on Municipal Solid Waste (MSW) subjected to one-dimensional compression in a 1 m{sup 3} instrumented cell. The focus was on the hydro-mechanical behavior of the material under conditions of confinement and leachate percolation that replicate those found in real-scale landfills. The operation of the apparatus is detailed together with the testing methodology and the monitoring program. Two samples of waste were tested: the first extended over a period of 10 months ('Control Test') and the second for 22 months ('Enhanced Test' with leachate recirculation). Consolidation data is reported with regard to both short-term (stress-dependent) and long-term (time-dependent) settlements. A discussion follows based on the derived values of primary and secondary compression ratios. Correlations between compression parameters and the biodegradation process are presented. In particular, results clearly highlight the effect of leachate recirculation on waste settlement: 24% secondary deformation reached after slightly less than 2 years (equivalent to a 5-fold increase in compressibility) and 17.9% loss of dry matter. Comparisons are proposed considering the results derived from the few monitoring programs conducted on experimental bioreactors worldwide. Finally, the hydraulic characterization of waste is discussed with regard to the evaluation of effective porosity and permeability.

  1. Hydro-mechanical behavior of municipal solid waste subject to leachate recirculation in a large-scale compression reactor cell.

    PubMed

    Olivier, Franck; Gourc, Jean-Pierre

    2007-01-01

    The paper presents the results of a laboratory experiment on Municipal Solid Waste (MSW) subjected to one-dimensional compression in a 1 m3 instrumented cell. The focus was on the hydro-mechanical behavior of the material under conditions of confinement and leachate percolation that replicate those found in real-scale landfills. The operation of the apparatus is detailed together with the testing methodology and the monitoring program. Two samples of waste were tested: the first extended over a period of 10 months ('Control Test') and the second for 22 months ('Enhanced Test' with leachate recirculation). Consolidation data is reported with regard to both short-term (stress-dependent) and long-term (time-dependent) settlements. A discussion follows based on the derived values of primary and secondary compression ratios. Correlations between compression parameters and the biodegradation process are presented. In particular, results clearly highlight the effect of leachate recirculation on waste settlement: 24% secondary deformation reached after slightly less than 2 years (equivalent to a 5-fold increase in compressibility) and 17.9% loss of dry matter. Comparisons are proposed considering the results derived from the few monitoring programs conducted on experimental bioreactors worldwide. Finally, the hydraulic characterization of waste is discussed with regard to the evaluation of effective porosity and permeability.

  2. Characterisation of the mechanical properties of infarcted myocardium in the rat under biaxial tension and uniaxial compression.

    PubMed

    Sirry, Mazin S; Butler, J Ryan; Patnaik, Sourav S; Brazile, Bryn; Bertucci, Robbin; Claude, Andrew; McLaughlin, Ron; Davies, Neil H; Liao, Jun; Franz, Thomas

    2016-10-01

    Understanding the passive mechanical properties of infarcted tissue at different healing stages is essential to explore the emerging biomaterial injection-based therapy for myocardial infarction (MI). Although rats have been widely used as animal models in such investigations, the data in literature that quantify the passive mechanical properties of rat heart infarcts is very limited. MI was induced in rats and hearts were harvested immediately (0 day), 7, 14 and 28 days after infarction onset. Left ventricle anterioapical samples were cut and underwent equibiaxial and non equibiaxial tension followed by uniaxial compression mechanical tests. Histological analysis was conducted to confirm MI and to quantify the size of the induced infarcts. Infarcts maintained anisotropy and the nonlinear biaxial and compressive mechanical behaviour throughout the healing phases with the circumferential direction being stiffer than the longitudinal direction. Mechanical coupling was observed between the two axes in all infarct groups. The 0, 7, 14 and 28 days infarcts showed 438, 693, 1048 and 1218kPa circumferential tensile moduli. The 28 day infarct group showed a significantly higher compressive modulus compared to the other infarct groups (p=0.0060, 0.0293, and 0.0268 for 0, 7 and 14 days groups). Collagen fibres were found to align in a preferred direction for all infarct groups supporting the observed mechanical anisotropy. The presented data are useful for developing material models for healing infarcts and for setting a baseline for future assessment of emerging mechanical-based MI therapies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Incidences of Deep Vein Thrombosis and Pulmonary Embolism after Total Knee Arthroplasty Using a Mechanical Compression Device with and without Low-Molecular-Weight Heparin.

    PubMed

    Park, Sin Hyung; Ahn, Joong Hyeon; Park, Yong Bok; Lee, Sun Geun; Yim, Soo Jae

    2016-09-01

    To investigate the incidence of thromboembolic events and complications related to bleeding after total knee arthroplasty (TKA) with a mechanical compression device alone or in combination with low-molecular-weight heparin (LMWH). A total of 489 TKA patients (776 knees) were retrospectively reviewed for the incidence of thromboembolic events and complications related to bleeding. While 233 patients (354 knees) were treated with a mechanical compressive device without LMWH, 256 patients (422 knees) were treated with the mechanical compressive device along with LMWH. The incidences of deep vein thrombosis (DVT) and pulmonary embolism (PE) were 15 of 375 knees (4.0%) and 5 of 375 knees (1.3%), respectively, in the group that used only a mechanical compressive device, and 14 of 401 knees (3.4%) and 5 of 401 knees (1.2%), respectively, in the group that used the mechanical compressive device with LMWH. There was no significant difference between the two groups (p=0.125 and p=0.146, respectively). The postoperative hemovac drainage amount was 635±57 mL in the group with a mechanical compressive device only and 813±84 mL in the group with the device and LMWH; therefore, the amount of drainage was significantly greater in the latter group (p=0.013). Mechanical compression alone for prophylaxis against DVT and PE after TKA can be an attractive option in Korean patients.

  4. Incidences of Deep Vein Thrombosis and Pulmonary Embolism after Total Knee Arthroplasty Using a Mechanical Compression Device with and without Low-Molecular-Weight Heparin

    PubMed Central

    Park, Sin Hyung; Ahn, Joong Hyeon; Park, Yong Bok; Lee, Sun Geun

    2016-01-01

    Purpose To investigate the incidence of thromboembolic events and complications related to bleeding after total knee arthroplasty (TKA) with a mechanical compression device alone or in combination with low-molecular-weight heparin (LMWH). Materials and Methods A total of 489 TKA patients (776 knees) were retrospectively reviewed for the incidence of thromboembolic events and complications related to bleeding. While 233 patients (354 knees) were treated with a mechanical compressive device without LMWH, 256 patients (422 knees) were treated with the mechanical compressive device along with LMWH. Results The incidences of deep vein thrombosis (DVT) and pulmonary embolism (PE) were 15 of 375 knees (4.0%) and 5 of 375 knees (1.3%), respectively, in the group that used only a mechanical compressive device, and 14 of 401 knees (3.4%) and 5 of 401 knees (1.2%), respectively, in the group that used the mechanical compressive device with LMWH. There was no significant difference between the two groups (p=0.125 and p=0.146, respectively). The postoperative hemovac drainage amount was 635±57 mL in the group with a mechanical compressive device only and 813±84 mL in the group with the device and LMWH; therefore, the amount of drainage was significantly greater in the latter group (p=0.013). Conclusions Mechanical compression alone for prophylaxis against DVT and PE after TKA can be an attractive option in Korean patients. PMID:27595075

  5. Effect of multimodality chest physiotherapy on the rate of recovery and prevention of complications in patients with mechanical ventilation: a prospective study in medical and surgical intensive care units.

    PubMed

    Pattanshetty, Renu B; Gaude, Gajanan S

    2011-05-01

    Mechanically ventilated patients have an increased risk of complications leading to ventilation weaning more difficult resulting in excessive morbidity and mortality. Chest physiotherapy plays an important role in management of ventilated patients. However, these techniques have been studied on patients as a single entity or with combination of two techniques. The present study was designed to evaluate the effect of multimodality chest physiotherapy on the rate of recovery and prevention of complications in adult ventilated patients. Out of 173 patients who were randomly allocated to two groups, 86 patients received MH and suctioning in control group and 87 patients were treated with multimodality chest physiotherapy in the study group twice daily till they were extubated. All patients were followed up for the global outcomes and complications during mechanical ventilation. There were significant improvements in terms of rate of recovery in study group compared to the control group (P = 0.000). Complication rates were higher with 61.6% in the control group as compared to 26.4% in the study group. Duration of hospitalization was longer in the study group (16 ± 9.40 days) as compared to the control group (12.8 ± 6.12 days). Successful weaning from mechanical ventilation was noted in 58 patients in the study group and 24 patients in the control group which was statistically significant. Multi-modality chest physiotherapy protocol has shown to prevent ventilator-associated pneumonia and enhance the clinical outcome in ventilated patients and may be recommended as a treatment option in ICU. It has also shown to enhance the weaning process and proved to be safe.

  6. [Chest injuries (author's transl)].

    PubMed

    Elert, O; Satter, P

    1979-04-01

    The mortality rate of chest injuries sustained during work or in road accidents stands now at 15-20%. The considerable force of the impact in road accidents is, in 60-80% of the cases, responsible for chest injuries which involve not only the chest wall but also the lungs. The extent and course of the lung damage must be assessed by repeated X-ray examinations, blood gas analyses and clinical observations. The decision to intubate and apply artificial ventilation should be made at an early stage. Fracture of a single rib needs only pain killers. If a rib is broken in several places or if several ribs are fractured instability of the chest wall is apt to develop in 15-20% of the cases. It manifests itself in paradoxical breathing and ensuing increase in the dead space. These cases require prompt "internal pneumatic splinting" in the form of positive pressure respiration and intubation. In recent years surgical stabilization of the chest wall has regained favour. Plate osteosynthesis, screw-less rib plates, self-gripping steel plates and steel splints are being used (Brunner, Hofmeister, Koncz). Primary osteosynthetic stabilization of the chest wall is indicated only if artificial ventilation has proved inadequate and there are other reasons for performing a thoracotomy. In these circumstances surgical intervention ensures that prolonged artificial ventilation and its attendent risks and complications and the demands made on the nursing staff are reduced to a minimum.

  7. HYDRODYNAMIC COMPRESSIVE FORGING.

    DTIC Science & Technology

    HYDRODYNAMICS), (*FORGING, COMPRESSIVE PROPERTIES, LUBRICANTS, PERFORMANCE(ENGINEERING), DIES, TENSILE PROPERTIES, MOLYBDENUM ALLOYS , STRAIN...MECHANICS), BERYLLIUM ALLOYS , NICKEL ALLOYS , CASTING ALLOYS , PRESSURE, FAILURE(MECHANICS).

  8. Induction of delayed wound healing by irradiation with optional mechanical compression in swine.

    PubMed

    Jeong, Woonhyeok; Oh, Daemyung; Kwon, Sunyoung; Kim, Jinhee; Son, Daegu

    2016-11-01

    A chronic wound or non-healing wound is one that fails to heal for at least 30 days after injury. This study was designed to create delayed wound healing induced by irradiation and mechanical compression using silicone block. Two female pigs received a single fraction of 20 Gy with 6-MeV electrons to a 22 × 60 cm field on the dorsal body skin 7 weeks before experimentation. A 30 × 30 mm sized wounds were created with preservation of muscle fascia on the dorsum. In groups of six, wounds were designated to be control (C) or test areas of irradiation only (T0), irradiation with silicone blocks for 1 week (T1), irradiation with silicone blocks for 2 weeks (T2), and irradiation with silicone blocks for 3 weeks (T3). Wound contraction, bacterial culture, and histological analysis were performed at 1-week intervals for 4 weeks. Control wounds displayed complete re-epithelialization at Weeks 4; however, all experimental groups (T0, T1, T2, and T3 groups) showed necrosis and delayed healing at Week 4. The number of bacterial strains in control wounds differed significantly from values recorded for all experimental groups from Weeks 1-3 (p < 0.05). However, in comparing the various test wounds (T0, T1, T2, and T3 groups), the numbers of strains did not differ significantly from Weeks 1-4. In the histological analysis, the control wound showed a peak influx of acute and chronic inflammatory cell and diminished inflammation thereafter. However, all experimental groups showed no peak in inflammatory score and prolonged chronic inflammation. In conclusion, radiation exposure alone, which triggers intense inflammation and extensive recruitment of inflammatory cells, proved sufficient to prevent re-epithelialization of skin at 30 days. Insertion of silicone blocks had limited effects on promoting delayed wound healing. Consequently, we now recommend using irradiation alone to simulate delayed wound healing in an experimental setting. Copyright © 2016 Tissue Viability

  9. Numerical study of mechanical behavior of ceramic composites under compression loading in the framework of movable cellular automaton method

    SciTech Connect

    Konovalenko, Igor S. Smolin, Alexey Yu. Konovalenko, Ivan S.; Promakhov, Vladimir V.; Psakhie, Sergey G.

    2014-11-14

    Movable cellular automaton method was used for investigating the mechanical behavior of ceramic composites under uniaxial compression. A 2D numerical model of ceramic composites based on oxides of zirconium and aluminum with different structural parameters was developed using the SEM images of micro-sections of a real composite. The inf