Purpose: Because overall EMS system response depends on ambulance availability, we conducted a prospective study of the EMS turnaround interval. This interval consists of the delivery and recovery intervals as defined in Spaite's EMS time-interval model.

Methods: An on-site observer, while monitoring EMS radio traffic, recorded the delivery and recovery activities of personnel from a large urban EMS system at a university hospital ED. System policy permits a maximum 30 minute turnaround interval. Prospectively defined subintervals were analyzed.

Results: A convenience sample of 122 patient deliveries was collected. Observed and radio-reported arrival at the hospital differed by -1′24″; to +11′8″. Time from arrival to removal of the patient from the ambulance averaged 59″ (range 13″-2′53″), and time from patient removal to ED entry averaged 42″ (10″ - 5′22″). While the mean time for the verbal report to ED staff was 33″ (2″-5′20″), it was 0 = 15″ in 36% of cases. Time from ED entry to placement of the patient on an ED bed averaged 2′11″ (33″-9′35″). Writing the report averaged 17′12″ (5′20″-52′11″). The mean time off radio was 29′51″ (ll′43″-53′37″) and the mean time the ambulance was at the ED was 30′01″ (11′25″-1°17′53″). Observed and radio-reported ambulance departures differed by -4′31″ to +23′32″. In 22% of cases, departure was reported on radio more than 5′after actual departure.