Background Many studies over the past decade have investigated delaying initial defibrillation to perform cardiopulmonary resuscitation (CPR), as it has been associated with increased rates of restoration of spontaneous circulation and/or survival. Since 2006, a number of studies have investigated these procedures. The objective of this study was to undertake a literature review examining the commencement of CPR before defibrillation in the out-of-hospital setting.

Methods A literature review was undertaken using the electronic medical databases Ovid Medline, EMBASE, CINHAL Plus, Cochrane Systematic Review and Meditext, from their commencement to the end of June 2011. Keywords used in the search included: CPR, defibrillation, ventricular fibrillation, VF, EMS, EMT, paramedic, emergency medical service, emergency medical technician, prehospital, out-of-hospital and ambulance. References of relevant articles were also reviewed.

Findings Of the 3079 articles located, 10 met the inclusion criteria. The results of these studies showed conflicting results. All retrospective studies (n=6) indicated a benefit in performing pre-shock CPR on patients with ventricular fibrillation for durations between 90 and 180 s. Conversely, all randomised controlled trials demonstrated no benefit from providing CPR before defibrillation compared with immediate defibrillation for return of spontaneous circulation, neurological outcome and/or survival to hospital discharge. However, none of the studies reported evidence that CPR before defibrillation is harmful.

Conclusion Conflicting evidence remains regarding the benefit of CPR before defibrillation. The establishment of a consistent timeframe of chest compressions before defibrillation in the out-of-hospital setting will provide uniformity in standards in clinical practice and education and training.