Objectives: To assess whether outcome and first–monitored rhythm for patients who sustain a witnessed, nonmonitored, out–of–hospital cardiac arrest are associated with on–scene CPR provider group.
Methods: A retrospective, cohort analysis was conducted in a suburban, heterogeneous EMS system. Patients studied were ± 19 years of age, had had an arrest of presumed cardiac origin between July 1989 and January 1993, had gone into cardiac arrest prior to ALS arrival, and had received CPR on collapse. First–monitored rhythms and survival rates were compared for two patient groups who on collapse either: 1) had received CPR by nonprofessional bystanders (BCPR) or 2) had received CPR by on–scene EMS system first responders (FRCPR).
Results: Of 217 cardiac arrest victims, 153 (71%) had received BCPR and 64 (29%) had received FRCPR. The BCPR patients were slightly younger (62. 4 vs 68. 4 years, p = 0. 01) and had slightly shorter ALS response intervals (6. 4 vs 7. 7 minutes, p = 0. 02). There was no difference in BLS response time intervals or automatic external defibrillator (AED) use rates. The percentage of patients with a first–monitored rhythm of pulseless ventricular tachycardia/ventricular fibrillation (VT/VF) and the percentage of patients grouped by CPR provider who survived to hospital admission or to hospital discharge were:
Controlling for age, the odds ratio for VT/VF with BCPR was 5. 45 (95% CI 2. 8, 10. 3).
Conclusion: Patients who receive BCPR more often have a first–monitored rhythm of VT/VF than do FRCPR patients, despite both CPR–provider groups' initiating CPR essentially immediately after patient collapse. Hence, BCPR and FRCPR groups have different first–monitored arrest rhythms, which may affect survival rate. These patient populations should not be considered to be homogeneous groups in CPR research.