Out-of-hospital cardiac arrest patients treated by emergency medical systems in Sweden 1990-1995

Abstract

Between Jan 1990 and May 1995 the Swedish Cardiac Arrest Registry collected and analysed 14,065 standardised reports on cardiac arrests. The reports emanated from approximately half of Sweden's ambulance districts, which cover five of Sweden's 8.7 million inhabitants. From 1983 to 1995 approximately 15-20% of the inhabitants had been trained in CPR.Method: A prospective, observational study of cardiac arrests reported to the Swedish Cardiac Arrest Registry. Results: Resuscitation was attempted in 10,966 cases. The median age was 70 years. In 70% the arrest was witnessed, and in 43% patients had ventricular fibril--lation (VF). The incidence of VF at the time of cardiac arrest was estimated to be 80% in the cases with probable heart disease. In 1,692 cases (15.4 %) the patient was admitted alive in hospital and 544 patients (5.0 %) were alive after one month. Survival to one month in the subgroup with VF was 9.5 % and 1.6% for patients with non-shockable rhythm. The survivors were analysed in relation to time to defibrillation and we found a strong correlation between a short time and increased survival. Bystander cardiopulmonary resuscitation (B-CPR) was initiated in 36% of the cases. In 56% of these cases, the bystanders were lay persons and in 28% they were medical personnel. Most of the arrests took place at home (65%) and only 23% of these patients were given B-CPR in contrast to cardiac arrest in other places where 53% were given CPR. Survival to one month was significantly higher in all cases that received B-CPR (8.2% vs. 2.5%). The odds ratio for survival to one month with B-CPR was in a logistic regression analysis 2.5 (95% CI 1.9-3.1). Factors that were associated with the effect of B-CPR were the interval between the collapse and the start of B-CPR, the completeness of B-CPR, whether or not the bystander was a layperson, the interval between collapse and the arrival of the ambulance, age and the place of arrest. Adrenalin was given in 42% and 48% were intubated. Among patients given adrenalin 3.4% were alive after one month and among patients who were intubated 3.6% were alive after one month. In a multivariate analysis treatment with adrenalin and intubation were both independently associated with predictors of a lower chance of survival.Conclusion: In a survey in Sweden of out-of-hospital cardiac arrests the overall sur-vival was low (5.0%). Survival for the patients with VF was 9.5%. Initial incidence of VF was estimated to be 80% in patients with probable heart disease. Survival decreased with increasing time to defibrillation. Bystander-CPR increased survival two to three times. Intubation and adrenalin were not associated with an increased survival.