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What Is the Optimal Chest Compression Depth During Out-of-Hospital Cardiac Arrest Resuscitation of Adult Patients?
Study Questions:
What is the optimal chest compression depth during resuscitation out-of-hospital cardiac arrest victims?
Methods:
Patients who had suffered an out-of-hospital nontraumatic cardiopulmonary arrest were included in the study. Patients who were treated with defibrillation or chest compression by emergency medical service (EMS) personnel, with any presenting rhythm, were included. Compression depth was measured by an accelerometer on the defibrillation electrode. During the study period, patients were being treated as per the 2005 guidelines for compression depth (38-50 mm). Patients who did not have attempts at cardiopulmonary resuscitation (CPR) by EMS or received a shock with a bystander-applied automatic external defibrillator were excluded. The primary outcome was survival to hospital discharge.
Results:
The study group consisted of 9,136 patients (13% at a public location, 44% bystander witnessed, and 42% bystander CPR). Thirty-one percent of the patients had return of spontaneous circulation, 23% survived 1 day, and 7% survived to hospital discharge. The median chest compression depth was 41 mm. The compression depth was not within the recommended range (38-50 mm) in 40% of cases. For survival to discharge, the odds ratio was 1.04 (95% confidence interval, 1.00-1.08) per each 5 mm increment in compression depth. Maximal survival was found at a depth of 46 mm (15 mm interval with highest survival between 40 and 55 mm).
Conclusions:
The authors concluded that increasing compression depth is associated with improved survival among patients who suffered an out-of-hospital cardiac arrest.
Perspective:
The 2010 guidelines recommend a compression depth >50 mm. The results of this study suggest this may be too high, as maximal survival was found at a depth of 46 mm. Since compression depth is inversely related to compression rate, the optimal rate may be sacrificed at higher depths. To assist rescuers to stay ‘in range’ and hence provide ideal CPR, a variety of strategies have been proposed, including reinforcing key principles and real-time feedback.
Keywords: Defibrillators, Out-of-Hospital Cardiac Arrest, Emergency Medical Services, Cardiopulmonary Resuscitation, Electric Countershock, Heart Arrest
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