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Circulation. 2002 May 14;105(19):2270-3.

Effects of interrupting precordial compressions on the calculated probability of defibrillation success during out-of-hospital cardiac arrest.

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Stavanger University College, Department of Electrical and Computer Engineering, Stavanger, Norway.



Cardiopulmonary resuscitation (CPR) creates artifacts on the ECG and, with automated defibrillators, a pause in CPR is mandatory during rhythm analysis. The rate of return of spontaneous circulation (ROSC) is reduced with increased duration of this hands-off interval in rats. We analyzed whether similar hands-off intervals in humans with ventricular fibrillation causes changes in the ECG predicting a lower probability of ROSC.


The probability of ROSC after a shock was continually determined from ECG signal characteristics for up to 20 seconds of 634 such hands-off intervals in patients with ventricular fibrillation. In hands-off intervals with an initially high (40% to 100%) or median (25% to 40%) probability for ROSC, the probability was gradually reduced with time to a median of 8% to 11% after 20 seconds (P<0.001). In episodes with a low initial probability (0% to 25%; median, 5%), there was no further reduction with time.


The interval between discontinuation of chest compressions and delivery of a shock should be kept as short as possible.

[Indexed for MEDLINE]

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