[Extrahospital cardiac arrest: the experience of Mestre Emergency Service]

Out-of-hospital cardiac arrest (AC) is one of the leading causes of death in industrialized countries. AC-related mortality can be reduced by rapid intervention. We report the experience of the emergency medical service (EMS) of Mestre on the management of out-of-hospital AC.

We analyzed 80 cases of out-of-hospital AC observed consecutively by the EMS of Mestre from February 1996 to September 1997: 72 cases (90.0%) involved cardiac etiology and 8 (10.0%) non-cardiac etiology. The 72 cases involving cardiac etiology were divided in three groups: group A) 12 unwitnessed ACs (16.7%); group B) 12 ACs witnessed by EMS personnel (16.7%); group C) 48 bystander-witnessed ACs (66.6%).

In group A, in which 4/12 patients (33.3%) presented ventricular fibrillation (FV) or pulseless ventricular tachycardia (TV) as initial rhythm, return of spontaneous circulation (ROSC) was obtained in one patient with FV and in one patient with asystole. In group B, 7/12 patients (58.3%) presented FV or TV as initial rhythm; in this subgroup, ROSC was obtained in 71.4% of cases (4 cases with FV and one case with TV) and discharge in 42.9%, while in the subgroup with other rhythms the rate of ROSC was 40.0% (two patients with pulseless electrical activity later died). In group C, 35/48 patients (72.9%) presented VF or TV as initial rhythm; in this subgroup, ROSC was achieved in 42.9% of cases (13 cases with FV and 2 cases with TV) and discharge in 14.3%, while in the subgroup of bystander-witnessed AC with other rhythms the rate of ROSC was extremely low (7.7%) (one patient with asystole later discharged). In group C, bystander cardiopulmonary resuscitation (CPR) was performed in 20/48 patients (40.1%). In these patients, FV or TV were more frequently recorded as initial rhythm (80.0 vs 67.9%; p < 0.05). In patients without bystander CPR, the interval between the time of collapse and the time of the first defibrillation was shorter in the patients who were admitted than in patients who died (6.0 +/- 1.4 vs 10.9 +/- 4.4 min; p < 0.05). Considering all patients with FV or TV as initial rhythm and the interval between the collapse and the first defibrillation exactly recorded, the percentage of ROSC decreased when the interval between the collapse and the first defibrillation increased.

Our data confirm that early defibrillation is the key factor in the prognosis of out-of-hospital AC. The data suggest that the immediate delivery of bystander CPR could extend the interval in which defibrillation is effective.