Does temporary location of ambulances ("fluid deployment") affect response times and patient outcome?

Background:  The objective of this paper is to evaluate the response times and outcome of patients in two groups of patients attended by permanently (PS) and temporarily stationed ambulances (TS) (fluid deployment).

Methods: Patients transported and treated by EMS between March 21, 2012 and March 20, 2013 in a city with 1.7 million inhabitants (Shiraz, Iran) were studied. Using the same number of ambulances, patients were divided into two groups: transported by ambulances dispatched from permanent ambulance stations (PS) vs. dispatched from temporary locations (TS). Furthermore, due to a high discrepancy in the number of missions between PS and TS in this group, a pilot study was also conducted to confirm the first result. The results were statistically analyzed using various methods and compared with regard to mortality and response time.

Results: In this study (both periods), ambulances dispatched from TS had a reduction of their mean response times by 2 min compare to ambulances dispatched from PS. The difference was statistically significant (p < 0.001-[95 % CI, 1.975, 2.025]). The pre-hospital mortality rate was also significantly lower for this group (p = 0.04-[95 % CI, 0.006, 0.012]).

Conclusions: The results of this study suggest that temporary deployment of ambulances reduce response times and may improve early survival rates in patients managed by EMS.