Effect of a ground critical care transport service on air medical helicopter utilization

To investigate the effect of adding a ground critical care ambulance service on the utilization of the pre-existing helicopter air ambulance.

A retrospective review of the requests for the helicopter was performed during each of three periods: one year prior to initiation of the ground service; the first six months after initiation of the ground service, during which the ground critical care ambulance operated 12 hours daily; and the subsequent six months, during which the ground critical care ambulance operated 24 hours daily. To control for any increase in the demand for health care services, hospital admission rates were used to standardize the helicopter utilization data. Means were compared using ANOVA.

Prior to initiation of the ground service, flight requests averaged 82 per month. During the period when the ground service was in place on a 24-hour basis, flight requests averaged 105 per month, a significant increase (p = 0.0010). Although hospital admissions during the same period increased (2,410 to 2,624, p = 0.0001), demand for the helicopter service increased at a faster rate. Flights per 100 admissions increased from 2.3 to 2.9, which is statistically significant (p = 0.0152).

The attempt to decrease the demand for a helicopter air ambulance by initiating a parallel ground ambulance service was not successful. Programs adding a ground critical care ambulance to existing helicopter services should not expect a decrease in utilization of the helicopter. These services should be viewed as complementary but not interchangeable.