Objectives: The aim of this study was to analyze the quality of chest compressions in different working situations pertaining to ambulance crews using either standard chest compressions (S-CC) or LUCAS mechanical ches...Objectives: The aim of this study was to analyze the quality of chest compressions in different working situations pertaining to ambulance crews using either standard chest compressions (S-CC) or LUCAS mechanical chest compressions (L-CC) in a manikin setting. Participants and Methods: Cardiopulmonary resuscitation (CPR) was performed using a compression to ventilation ratio of 30:2 with both S-CC and L-CC. Quality parameters were collected using a modified manikin enabling impedance measurements. The evaluation was performed in two manikin scenarios: Scenario 1 evaluated ten minutes of CPR on the ground and Scenario 2 assessed six minutes of CPR in different settings relevant to work in the ambulance. Quality parameters compared were: time to apply LUCAS, hands-off fraction, number of correct chest compressions and the rate of compressions. Results: In Scenario 1 the hands-off fraction was higher when S-CC was performed (S-CC group 29% vs. L-CC 16%, P = 0.003). We found a higher number of chest compressions (S-CC = 913 vs. L-CC = 831, P = 0.0049) and a higher rate of chest compressions (S-CC = 118 vs. L-CC = 99, P < 0.0001) in the S-CC group. In Scenario 2 we noted a higher hands-off fraction for S-CC (39% vs. L-CC = 19%, P = 0.003), but a higher number of compressions given during S-CC ((n = 504) vs. L-CC (n = 396) P = 0.0002). Conclusion: Mechanical chest compression with the LUCAS 2TM device enables ambulance personnel to provide high quality chest compression even while transporting the patient.展开更多
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 ...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.展开更多
Purpose: According to guideline recommendations, chest compressions (CC) during cardiopulmonary resuscitation (CPR) should be performed at a rate of 100 - 120 per minute, with a CC fraction (CCF) of ≥80%. The aim of ...Purpose: According to guideline recommendations, chest compressions (CC) during cardiopulmonary resuscitation (CPR) should be performed at a rate of 100 - 120 per minute, with a CC fraction (CCF) of ≥80%. The aim of this work is to explore whether CC quality differs between advanced life support (ALS) and basic life support (BLS) performed by two rescuers. Method: Cardiopulmonary resuscitation was performed by two ambulance personnel in ten ALS and ten BLS manikin scenarios. Data from these scenarios were then compared with data on ten ALS cases from the clinical setting, all with non-shockable rhythms. Data from the first two 5-minute periods of CC were evaluated from impedance data (LIFEPAK 12 defibrillator monitors) using a modified Laerdal Skillmaster manikin. Quality parameters compared were: number of CC pauses (CCPs), total time of CC (%), number of CC given and CC rate/min. Results: During the first 5 minutes, the BLS manikin scenarios had the highest number of CCPs, 15 (14 - 16), compared with the ALS manikin scenario, 14 (13 - 15), and the clinical ALS cases, 12 (10 - 15). The BLS scenario also had the highest CCFs, 81% (77% - 85%), and number of CC, 450 (435 - 495), compared with the ALS manikin scenario, 75% (64% - 81%) and 400 (365 - 444) respectively, and the clinical ALS cases, 63% (50% - 74%) and 408 (306 - 489). The median rate of CC/min in the BLS scenario was 115 (110 - 120) compared with the ALS manikin scenario, 110 (106 - 115), and the clinical ALS cases, 130 (118 - 146). During the second 5-minute period, the BLS scenario had the highest number of CCPs, 16 (15 - 17), compared with 15 (14 - 16) for the ALS manikin scenario and 11 (11 - 12) for the clinical ALS cases. The CCF in the BLS setting was 79% (75% - 83%), and the number of CC 455 (430 - 480), compared with the ALS manikin scenario, 79% (74% - 84%) and 435 (395 - 480) respectively, and the clinical ALS cases, 71% (57% - 77%) and 388 (321 - 469) respectively. The median CC rate was 118 (113 - 124) for BLS, 111 (105 - 120) for ALS manikins and 123 (103 - 128) CC/min for clinical ALS cases. Conclusion: None of the groups being studied could deliver CC at a rate of 100 - 120 CC/min or a CCF of ≥80% over the whole 10-minute period in any of the resuscitation scenarios analyzed. However, BLS had the best compliance with CC quality recommendations according to the 2010 guidelines.展开更多
BACKGROUND It remains unclear whether video aids can improve the quality of bystander cardiopulmonary resuscitation(CPR).AIM To summarize simulation-based studies aiming at improving bystander CPR associated with the ...BACKGROUND It remains unclear whether video aids can improve the quality of bystander cardiopulmonary resuscitation(CPR).AIM To summarize simulation-based studies aiming at improving bystander CPR associated with the quality of chest compression and time-related quality parameters.METHODS The systematic review was conducted according to the PRISMA guidelines.All relevant studies were searched through PubMed,EMBASE,Medline and Cochrane Library databases.The risk of bias was evaluated using the Cochrane collaboration tool.RESULTS A total of 259 studies were eligible for inclusion,and 6 randomised controlled trial studies were ultimately included.The results of meta-analysis indicated that video-assisted CPR(V-CPR)was significantly associated with the improved mean chest compression rate[OR=0.66(0.49-0.82),P<0.001],and the proportion of chest compression with correct hand positioning[OR=1.63(0.71-2.55),P<0.001].However,the difference in mean chest compression depth was not statistically significant[OR=0.18(-0.07-0.42),P=0.15],and V-CPR was not associated with the time to first chest compression compared to telecommunicator CPR[OR=-0.12(-0.88-0.63),P=0.75].CONCLUSION Video real-time guidance by the dispatcher can improve the quality of bystander CPR to a certain extent.However,the quality is still not ideal,and there is a lack of guidance caused by poor video signal or inadequate interaction.展开更多
Background The effects of chest compressions to hemodynamic and respiratory parameters during hands-only cardiopulmonary resuscitation (CPR) in a non-arrested patient who suddenly collapses are confusing.In this res...Background The effects of chest compressions to hemodynamic and respiratory parameters during hands-only cardiopulmonary resuscitation (CPR) in a non-arrested patient who suddenly collapses are confusing.In this research,we investigated the effects of chest compressions in a non-arrested porcine model.Methods Fourteen male domestic pigs were randomized into sham control group (SHAM group,only anesthetized and instrumented without chest compression,n=6) or chest compression group (CC group,2 minutes of chest compressions,n=8).Continuous hemodynamic parameters,dynamic lung compliance (Cdyn),and blood gas analysis outcomes were recorded.Serum levels of catecholamine were measured at baseline and 2 minutes,30 minutes,4 hours,and 24 hours after chest compressions.Chest computed tomography (CT) was performed at 30 minutes and 24 hours.Conventional histopathology evaluation was performed.Results After two minutes of chest compressions in the CC group,heart rate and extravascular lung water increased significantly; mean arterial pressure,stroke volume,and global ejection fraction significantly decreased.Cdyn significantly decreased to valley levels at 30 minutes and slowly recovered.Compared with the baseline,serum levels of catecholamine significantly increased at 2 minutes and rapidly decreased 24 hours later.At 30 minutes after chest compressions,chest CT showed local exudation,which was absorbed 24 hours later.Conclusions This research showed that 2 minutes of chest compressions causes various heart and lung tissue damage in the normal a normal porcine model.It also impacts the hemodynamic and Cdyn.展开更多
Out-of-hospital cardiac arrest is a life threatening situation where the first person performing car-diopulmonary resuscitation (CPR) most often is a bystander without medical training. Some existing smart phone apps ...Out-of-hospital cardiac arrest is a life threatening situation where the first person performing car-diopulmonary resuscitation (CPR) most often is a bystander without medical training. Some existing smart phone apps can call the emergency number and provide for example global positioning system (GPS) loca-tion by the Norwegian air ambulance. To extend functionality of such apps by using the built in camera in a smart phone to capture video of the CPR performed, primarily to estimate the duration and rate of the chest compression executed.展开更多
BACKGROUND: The quality of chest compressions can be significantly improved after training of rescuers according to the latest national guidelines of China. However, rescuers may be unable to maintain adequate compres...BACKGROUND: The quality of chest compressions can be significantly improved after training of rescuers according to the latest national guidelines of China. However, rescuers may be unable to maintain adequate compression or ventilation throughout a response of average emergency medical services because of increased rescuer fatigue. In the present study, we evaluated the performance of cardiopulmonary resuscitation(CPR) in training of military medical university students during a prolonged basic life support(BLS).METHODS: A 3-hour BLS training was given to 120 military medical university students. Six months after the training, 115 students performed single rescuer BLS on a manikin for 8 minutes. The qualities of chest compressions as well as ventilations were assessed.RESULTS: The average compression depth and rate were 53.7±5.3 mm and 135.1±15.7 compressions per minute respectively. The proportion of chest compressions with appropriate depth was 71.7%±28.4%. The average ventilation volume was 847.2±260.4 m L and the proportion of students with adequate ventilation was 63.5%. Compared with male students, significantly lower compression depth(46.7±4.8 vs. 54.6±4.8 mm, P<0.001) and adequate compression rate(35.5%±26.5% vs. 76.1%±25.1%, P<0.001) were observed in female students.CONCLUSIONS: CPR was found to be related to gender, body weight, and body mass index of students in this study. The quality of chest compressions was well maintained in male students during 8 minutes of conventional CPR but declined rapidly in female students after 2 minutes according to the latest national guidelines. Physical fitness and rescuer fatigue did not affect the quality of ventilation.展开更多
BACKGROUND: The survival rate of patients after cardiac arrest(CA) remains lower since 2010 International Consensus on Cardiopulmonary Resuscitation(CPR) and Emergency Cardiovascular Care(ECC) was published. In clinic...BACKGROUND: The survival rate of patients after cardiac arrest(CA) remains lower since 2010 International Consensus on Cardiopulmonary Resuscitation(CPR) and Emergency Cardiovascular Care(ECC) was published. In clinical trials, the methods and techniques for CPR have been overly described. This article gives an overview of the progress in methods and techniques for CPR in the past years.DATA SOURCES: Original articles about cardiac arrest and CPR from MEDLINE(PubM ed) and relevant journals were searched, and most of them were clinical randomized controlled trials(RCTs).RESULTS: Forty-two articles on methods and techniques of CPR were reviewed, including chest compression and conventional CPR, chest compression depth and speed, defibrillation strategies and priority, mechanical and manual chest compression, advanced airway management, impedance threshold device(ITD) and active compression-decompression(ACD) CPR, epinephrine use, and therapeutic hypothermia. The results of studies and related issues described in the international guidelines had been testifi ed.CONCLUSIONS: Although large multicenter studies on CPR are still difficult to carry out, progress has been made in the past 4 years in the methods and techniques of CPR. The results of this review provide evidences for updating the 2015 international guidelines.展开更多
This paper aims to improve the pre-hospital first-aid knowledge and pre-hospital first-aid success rate and optimize the pre-hospital emergency system.This paper mainly discusses a comprehensive pre-hospital emergency...This paper aims to improve the pre-hospital first-aid knowledge and pre-hospital first-aid success rate and optimize the pre-hospital emergency system.This paper mainly discusses a comprehensive pre-hospital emergency system,which consists of the hardware part and software part.The hardware is based on the international cardiopulmonary resuscitation guidelines,and a cardiopulmonary resuscitation(CPR)training auxiliary equipment is developed,which can be applied in pre-hospital first aid training to help people perform accurate chest compressions.The software part is based on the WeChat applet platform to set up a pre-hospital first-aid dispatching system that connects callers and CPR rescuers.The software system effectively improves the pre-hospital CPR first-aid system and increases the rescue success rate of cardiac arrest patients.展开更多
文摘Objectives: The aim of this study was to analyze the quality of chest compressions in different working situations pertaining to ambulance crews using either standard chest compressions (S-CC) or LUCAS mechanical chest compressions (L-CC) in a manikin setting. Participants and Methods: Cardiopulmonary resuscitation (CPR) was performed using a compression to ventilation ratio of 30:2 with both S-CC and L-CC. Quality parameters were collected using a modified manikin enabling impedance measurements. The evaluation was performed in two manikin scenarios: Scenario 1 evaluated ten minutes of CPR on the ground and Scenario 2 assessed six minutes of CPR in different settings relevant to work in the ambulance. Quality parameters compared were: time to apply LUCAS, hands-off fraction, number of correct chest compressions and the rate of compressions. Results: In Scenario 1 the hands-off fraction was higher when S-CC was performed (S-CC group 29% vs. L-CC 16%, P = 0.003). We found a higher number of chest compressions (S-CC = 913 vs. L-CC = 831, P = 0.0049) and a higher rate of chest compressions (S-CC = 118 vs. L-CC = 99, P < 0.0001) in the S-CC group. In Scenario 2 we noted a higher hands-off fraction for S-CC (39% vs. L-CC = 19%, P = 0.003), but a higher number of compressions given during S-CC ((n = 504) vs. L-CC (n = 396) P = 0.0002). Conclusion: Mechanical chest compression with the LUCAS 2TM device enables ambulance personnel to provide high quality chest compression even while transporting the patient.
基金supported by a grant from the Natural Science Fund of Hubei Province(2011CDB195)
文摘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.
文摘Purpose: According to guideline recommendations, chest compressions (CC) during cardiopulmonary resuscitation (CPR) should be performed at a rate of 100 - 120 per minute, with a CC fraction (CCF) of ≥80%. The aim of this work is to explore whether CC quality differs between advanced life support (ALS) and basic life support (BLS) performed by two rescuers. Method: Cardiopulmonary resuscitation was performed by two ambulance personnel in ten ALS and ten BLS manikin scenarios. Data from these scenarios were then compared with data on ten ALS cases from the clinical setting, all with non-shockable rhythms. Data from the first two 5-minute periods of CC were evaluated from impedance data (LIFEPAK 12 defibrillator monitors) using a modified Laerdal Skillmaster manikin. Quality parameters compared were: number of CC pauses (CCPs), total time of CC (%), number of CC given and CC rate/min. Results: During the first 5 minutes, the BLS manikin scenarios had the highest number of CCPs, 15 (14 - 16), compared with the ALS manikin scenario, 14 (13 - 15), and the clinical ALS cases, 12 (10 - 15). The BLS scenario also had the highest CCFs, 81% (77% - 85%), and number of CC, 450 (435 - 495), compared with the ALS manikin scenario, 75% (64% - 81%) and 400 (365 - 444) respectively, and the clinical ALS cases, 63% (50% - 74%) and 408 (306 - 489). The median rate of CC/min in the BLS scenario was 115 (110 - 120) compared with the ALS manikin scenario, 110 (106 - 115), and the clinical ALS cases, 130 (118 - 146). During the second 5-minute period, the BLS scenario had the highest number of CCPs, 16 (15 - 17), compared with 15 (14 - 16) for the ALS manikin scenario and 11 (11 - 12) for the clinical ALS cases. The CCF in the BLS setting was 79% (75% - 83%), and the number of CC 455 (430 - 480), compared with the ALS manikin scenario, 79% (74% - 84%) and 435 (395 - 480) respectively, and the clinical ALS cases, 71% (57% - 77%) and 388 (321 - 469) respectively. The median CC rate was 118 (113 - 124) for BLS, 111 (105 - 120) for ALS manikins and 123 (103 - 128) CC/min for clinical ALS cases. Conclusion: None of the groups being studied could deliver CC at a rate of 100 - 120 CC/min or a CCF of ≥80% over the whole 10-minute period in any of the resuscitation scenarios analyzed. However, BLS had the best compliance with CC quality recommendations according to the 2010 guidelines.
基金Supported by the Fundamental Research Funds for the Central Universities,Northwest Minzu University,Grant No.31920170180.
文摘BACKGROUND It remains unclear whether video aids can improve the quality of bystander cardiopulmonary resuscitation(CPR).AIM To summarize simulation-based studies aiming at improving bystander CPR associated with the quality of chest compression and time-related quality parameters.METHODS The systematic review was conducted according to the PRISMA guidelines.All relevant studies were searched through PubMed,EMBASE,Medline and Cochrane Library databases.The risk of bias was evaluated using the Cochrane collaboration tool.RESULTS A total of 259 studies were eligible for inclusion,and 6 randomised controlled trial studies were ultimately included.The results of meta-analysis indicated that video-assisted CPR(V-CPR)was significantly associated with the improved mean chest compression rate[OR=0.66(0.49-0.82),P<0.001],and the proportion of chest compression with correct hand positioning[OR=1.63(0.71-2.55),P<0.001].However,the difference in mean chest compression depth was not statistically significant[OR=0.18(-0.07-0.42),P=0.15],and V-CPR was not associated with the time to first chest compression compared to telecommunicator CPR[OR=-0.12(-0.88-0.63),P=0.75].CONCLUSION Video real-time guidance by the dispatcher can improve the quality of bystander CPR to a certain extent.However,the quality is still not ideal,and there is a lack of guidance caused by poor video signal or inadequate interaction.
文摘Background The effects of chest compressions to hemodynamic and respiratory parameters during hands-only cardiopulmonary resuscitation (CPR) in a non-arrested patient who suddenly collapses are confusing.In this research,we investigated the effects of chest compressions in a non-arrested porcine model.Methods Fourteen male domestic pigs were randomized into sham control group (SHAM group,only anesthetized and instrumented without chest compression,n=6) or chest compression group (CC group,2 minutes of chest compressions,n=8).Continuous hemodynamic parameters,dynamic lung compliance (Cdyn),and blood gas analysis outcomes were recorded.Serum levels of catecholamine were measured at baseline and 2 minutes,30 minutes,4 hours,and 24 hours after chest compressions.Chest computed tomography (CT) was performed at 30 minutes and 24 hours.Conventional histopathology evaluation was performed.Results After two minutes of chest compressions in the CC group,heart rate and extravascular lung water increased significantly; mean arterial pressure,stroke volume,and global ejection fraction significantly decreased.Cdyn significantly decreased to valley levels at 30 minutes and slowly recovered.Compared with the baseline,serum levels of catecholamine significantly increased at 2 minutes and rapidly decreased 24 hours later.At 30 minutes after chest compressions,chest CT showed local exudation,which was absorbed 24 hours later.Conclusions This research showed that 2 minutes of chest compressions causes various heart and lung tissue damage in the normal a normal porcine model.It also impacts the hemodynamic and Cdyn.
文摘Out-of-hospital cardiac arrest is a life threatening situation where the first person performing car-diopulmonary resuscitation (CPR) most often is a bystander without medical training. Some existing smart phone apps can call the emergency number and provide for example global positioning system (GPS) loca-tion by the Norwegian air ambulance. To extend functionality of such apps by using the built in camera in a smart phone to capture video of the CPR performed, primarily to estimate the duration and rate of the chest compression executed.
基金supported by a grant from the National Natural Science Foundation of China(NSFC81271656,YL)
文摘BACKGROUND: The quality of chest compressions can be significantly improved after training of rescuers according to the latest national guidelines of China. However, rescuers may be unable to maintain adequate compression or ventilation throughout a response of average emergency medical services because of increased rescuer fatigue. In the present study, we evaluated the performance of cardiopulmonary resuscitation(CPR) in training of military medical university students during a prolonged basic life support(BLS).METHODS: A 3-hour BLS training was given to 120 military medical university students. Six months after the training, 115 students performed single rescuer BLS on a manikin for 8 minutes. The qualities of chest compressions as well as ventilations were assessed.RESULTS: The average compression depth and rate were 53.7±5.3 mm and 135.1±15.7 compressions per minute respectively. The proportion of chest compressions with appropriate depth was 71.7%±28.4%. The average ventilation volume was 847.2±260.4 m L and the proportion of students with adequate ventilation was 63.5%. Compared with male students, significantly lower compression depth(46.7±4.8 vs. 54.6±4.8 mm, P<0.001) and adequate compression rate(35.5%±26.5% vs. 76.1%±25.1%, P<0.001) were observed in female students.CONCLUSIONS: CPR was found to be related to gender, body weight, and body mass index of students in this study. The quality of chest compressions was well maintained in male students during 8 minutes of conventional CPR but declined rapidly in female students after 2 minutes according to the latest national guidelines. Physical fitness and rescuer fatigue did not affect the quality of ventilation.
文摘BACKGROUND: The survival rate of patients after cardiac arrest(CA) remains lower since 2010 International Consensus on Cardiopulmonary Resuscitation(CPR) and Emergency Cardiovascular Care(ECC) was published. In clinical trials, the methods and techniques for CPR have been overly described. This article gives an overview of the progress in methods and techniques for CPR in the past years.DATA SOURCES: Original articles about cardiac arrest and CPR from MEDLINE(PubM ed) and relevant journals were searched, and most of them were clinical randomized controlled trials(RCTs).RESULTS: Forty-two articles on methods and techniques of CPR were reviewed, including chest compression and conventional CPR, chest compression depth and speed, defibrillation strategies and priority, mechanical and manual chest compression, advanced airway management, impedance threshold device(ITD) and active compression-decompression(ACD) CPR, epinephrine use, and therapeutic hypothermia. The results of studies and related issues described in the international guidelines had been testifi ed.CONCLUSIONS: Although large multicenter studies on CPR are still difficult to carry out, progress has been made in the past 4 years in the methods and techniques of CPR. The results of this review provide evidences for updating the 2015 international guidelines.
基金Natural Science Foundation of Guangdong Province,grant number:2016KZDXM013
文摘This paper aims to improve the pre-hospital first-aid knowledge and pre-hospital first-aid success rate and optimize the pre-hospital emergency system.This paper mainly discusses a comprehensive pre-hospital emergency system,which consists of the hardware part and software part.The hardware is based on the international cardiopulmonary resuscitation guidelines,and a cardiopulmonary resuscitation(CPR)training auxiliary equipment is developed,which can be applied in pre-hospital first aid training to help people perform accurate chest compressions.The software part is based on the WeChat applet platform to set up a pre-hospital first-aid dispatching system that connects callers and CPR rescuers.The software system effectively improves the pre-hospital CPR first-aid system and increases the rescue success rate of cardiac arrest patients.