The impact of prehospital transport interval on survival in out-of-hospital cardiac arrest: implications for regionalization of post-resuscitation care.

OBJECTIVE: There is growing evidence that therapeutic hypothermia and other post-resuscitation care improves outcomes in out-of-hospital cardiac arrest (OHCA). Thus, transporting patients with return of spontaneous circulation (ROSC) to specialized facilities may increase survival rates. However, it is unknown whether prolonging transport to reach a designated facility would be detrimental.

METHODS: Data from OHCA patients treated in EMS systems that cover approximately 70% of Arizona's population were evaluated (October 2004-December 2006). We analyzed the association between transport interval (depart scene to ED arrival) and survival to hospital discharge in adult, non-traumatic OHCA patients and in the subgroup who achieved ROSC and remained comatose.

RESULTS: 1846 OHCA occurred prior to EMS arrival. Complete transport interval data were available for 1177 (63.8%) patients (study group). 253 patients (21.5%) achieved ROSC and remained comatose making them theoretically eligible for transport to specialized care. Overall, 70 patients (5.9%) survived and 43 (17.0%) comatose ROSC patients survived. Mean transport interval for the study group was 6.9 min (95% CI: 6.7, 7.1). Logistic regression revealed factors that were independently associated with survival: witnessed arrest, bystander CPR, method of CPR, initial rhythm of ventricular fibrillation, and shorter EMS response time interval. There was no significant association between transport interval and outcome in either the overall study group (OR=1.2; 0.77, 1.8) or in the comatose, ROSC subgroup (OR 0.94; 0.51, 1.8).

CONCLUSION: Survival was not significantly impacted by transport interval. This suggests that a modest increase in transport interval from bypassing the closest hospital en route to specialized care is safe and warrants further investigation.