Abstract

Many studies have shown that interruption of chest compressions in out-of-hospital cardiac arrest is an important factor that limits survival. This observational prospective study of patients with out-of-hospital cardiac arrest in Norway, Sweden and the UK set out to quantify in detail the effects of interrupting chest compressions. ECG segments showing ventricular fibrillation and pulseless ventricular tachycardia arrest were extracted and analysed by computing the logarithm of the mean slope which can be viewed as the coarseness of the ECG. Return of spontaneous circulation (ROSC) was identified by either changes in transthoracic impedance coincident with QRS complex or by a clinically detected pulse. Measurements of depth of compressions were used to ascertain the presence or absence of chest compressions. The study found that during pre-shock pauses in chest compressions there is a decrease in the probability of ROSC of approximately 23% from 3 s to 27 s into such a pause. Prehospital care providers should bear this in mind during resuscitation and ensure interruptions in chest compressions are kept to a minimum duration.

Sarah Christopher, College of Paramedics Research and Audit Committee

▶ Gundersen K, Kvaloy J, Kramer-Johansen J, et al. Development of the probability of return of spontaneous circulation in intervals without chest compressions during out-of-hospital cardiac arrest: an observational study. BMC Med 2009;7:6.