Case and survival definitions in out-of-hospital cardiac arrest. Effect on survival rate calculation
T. D. Valenzuela, D. W. Spaite, H. W. Meislin, L. L. Clark, A. L. Wright and G. A. Ewy
Arizona Emergency Medicine Research Center, Tucson.
OBJECTIVE--To determine the effect of different case and survival
definitions of out-of-hospital cardiac arrest on survival rate
calculations. DESIGN--A 22-month case series of nontraumatic,
out-of-hospital cardiac arrests. SETTING--Southwestern city (population,
400,000; area, 390 km2) with a two-tiered emergency response system
consisting of emergency medical technicians and paramedics. PATIENTS--A
consecutive sample of 372 patients found without palpable pulse of
spontaneous respiration. MAIN OUTCOME MEASURES--Survival rate after cardiac
arrest was calculated using three case definitions of arrest and two
definitions of survival. RESULTS--Twenty percent of all patients survived
to hospital admission and 6% survived to hospital discharge. Twenty-six
percent of adults whose collapse was witnessed survived to hospital
admission, and 10% survived to hospital discharge. Patients whose collapse
was witnessed and who experienced initial ventricular fibrillation survived
to hospital admission in 38% and to hospital discharge in 15% of cases.
CONCLUSIONS--The survival rate after out-of-hospital cardiac arrest varies
widely depending on the case and survival definitions selected. To
facilitate intersystem comparison and assessment of interventions designed
to improve outcome, the Utstein Consensus Conference recommended that case
and survival definitions should be adopted by all prehospital emergency
systems.
