Abstract
BackgroundHands-Only cardiopulmonary resuscitation (CPR) is recommended for use on adult victims of witnessed out-of-hospital (OOH) sudden cardiac arrest or in instances where rescuers cannot perform ventilations while maintaining minimally interrupted quality compressions. Promotion of Hands-Only CPR should improve the incidence of bystander CPR and, subsequently, survival from OOH cardiac arrest; but, little is known about a rescuer's ability to deliver continuous chest compressions of adequate rate and depth for periods typical of emergency services response time. This study evaluated chest compression rate and depth as subjects performed Hands-Only CPR for 10 minutes. For comparison purposes, each also performed chest compressions with ventilations (30:2) CPR. It also evaluated fatigue and changes in body biomechanics associated with each type of CPR.MethodsTwenty healthy female volunteers certified in basic life support performed Hands-Only CPR and 30:2 CPR on a manikin. A mixed model repeated measures cross-over design evaluated chest compression rate and depth, changes in fatigue (chest compression force, perceived exertion, and blood lactate level), and changes in electromyography and joint kinetics and kinematics.ResultsAll subjects completed 10 minutes of 30:2 CPR; but, only 17 completed 10 minutes of Hands-Only CPR. Rate, average depth, percentage at least 38 millimeters deep, and force of compressions were significantly lower in Hands-Only CPR than in 30:2 CPR. Rates were maintained; but, compression depth and force declined significantly from beginning to end CPR with most decrement occurring in the first two minutes. Perceived effort and joint torque changes were significantly greater in Hands-Only CPR. Performance was not influenced by age.ConclusionHands-Only CPR required greater effort and was harder to sustain than 30:2 CPR. It is not known whether the observed greater decrement in chest compression depth associated with Hands-Only CPR would offset the potential physiological benefit of having fewer interruptions in compressions during an actual resuscitation. The dramatic decrease in compression depth in the first two minutes reinforces current recommendations that rescuers take turns performing compressions, switching every two minutes or less. Further study is recommended to determine the impact of real-time feedback and dispatcher coaching on rescuer performance.
Highlights
Hands-Only cardiopulmonary resuscitation (CPR) is recommended for use on adult victims of witnessed out-of-hospital (OOH) sudden cardiac arrest or in instances where rescuers cannot perform ventilations while maintaining minimally interrupted quality compressions
To enhance survival of adult victims of cardiac arrest, the American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care, updated in 2005, recommend that rescuers deliver cardiopulmonary resuscitation (CPR) in cycles of 30 chest compressions and 2 ventilations (30:2 CPR) at a rate of 100 compressions per minute with a compression depth of 11⁄2 to 2 inches (38 to 51 millimetres)[1] If multiple rescuers are present, the guidelines recommend that rescuers take turns compressing the chest to help reduce fatigue, changing rescuer every 2 minutes
Hands-Only CPR has the potential for improving the chance of survival from OOH cardiac arrest by reducing the time to initiation of chest compressions and limiting interruptions in compressions associated with ventilations, resulting in a greater number of chest compression during the first few minutes after cardiac arrest[2] The AHA's 2008 Science Advisory acknowledges that further study is needed to assess the bystander's ability to deliver continuous chest compressions of adequate rate and depth for prolonged durations as might be required of a single bystander until further help arrives
Summary
Hands-Only cardiopulmonary resuscitation (CPR) is recommended for use on adult victims of witnessed out-of-hospital (OOH) sudden cardiac arrest or in instances where rescuers cannot perform ventilations while maintaining minimally interrupted quality compressions. Hands-Only CPR has the potential for improving the chance of survival from OOH cardiac arrest by reducing the time to initiation of chest compressions and limiting interruptions in compressions associated with ventilations, resulting in a greater number of chest compression during the first few minutes after cardiac arrest[2] The AHA's 2008 Science Advisory acknowledges that further study is needed to assess the bystander's ability to deliver continuous chest compressions of adequate rate and depth for prolonged durations as might be required of a single bystander until further help arrives. None of the research on rescuer ability to maintain adequate rate and depth of chest compressions has examined the recommended rescuer body position, the muscles activated to sustain the position, or the effect on the joints involved (wrist, shoulder, and hip)
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