Experimental studies on precordial compression or defibrillation as initial interventions for ventricular fibrillation

Countershock of prolonged ventricular fibrillation is usually followed by a systole or a nonperfusing rhythm. Data from three laboratory investigations indicate that administration of epinephrine and cardiopulmonary resuscitat ion (CPR) preceding countershock of prolonged ventricular fibrillation sign ificantly improves cardiac resuscitation outcome compared with immediate co untershock (relative risk reduction of failed resuscitation, 0.61), Prelimi nary investigations indicate that a similar improvement is not observed whe n the ventricular fibrillation period is of shorter duration, e.g., 5 mins, This time interval is probably at the lower limit at which CPR preceding s hock of ventricular fibrillation provides benefit in terms of cardiac resus citation. A single clinical trial of "CPR first" supports the use of a brie f period of CPR before countershock of prolonged ventricular fibrillation. Additional trials with and without epinephrine are anticipated.