The effect of the number and level of emergency medical technicians on patient outcomes following out of hospital cardiac arrest in Taipei

Aim The effect of the number and level of on-scene emergency medical technicians (EMTs) on the outcomes of patients with out-of-hospital cardiac arrest (OHCA) remains unclear. We aimed to test the association between the number and level of EMTs and the outcomes of patients with OHCA. Methods We analysed Utstein-based registry data on OHCA in Taipei from 2011 to 2015. The eligible patients were adults, aged ≥20 years, with non-traumatic OHCA who underwent resuscitation attempts. The exposures were the total number of EMTs or the EMT-Paramedic (EMT-P) ratio >50%. The outcome of interest was survival to discharge. Results During study period, total 8262 OHCA cases were included, of which 1085 (13.1%) were approached by crews with an EMT-P ratio >50%. While an increase in the number of EMTs on-scene was not associated with better chances of survival (adjusted odds ratio [aOR] 0.98, 95% confidence interval [CI] 0.89–1.08), an EMT-P ratio >50% was significantly associated with improved outcome (aOR 1.36, 95% CI 1.06–1.76). Subgroup analyses showed that EMT-P >50% significantly benefited survival in witnessed OHCA cases with non-shockable rhythm (aOR 1.69, 95% CI 1.01–2.58). Survival was the highest among cases seen by four EMTs with an EMT-P ratio >50% (aOR 2.54, 95% CI 1.43–4.50). Conclusion An on-scene EMT-P ratio >50% was associated with improved survival to discharge of OHCA cases, especially in those with witnessed, non-shockable rhythm. The presence of four EMTs with an EMT-P ratio >50% at the scene of OHCA was associated with the best outcome.