Interactive effect of multi-tier response and advanced airway management on clinical outcomes after out-of-hospital cardiac arrest: a nationwide population-based observational study

OBJECTIVE: We hypothesized that a multi-tier response (MTR) will provide high-quality cardiopulmonary resuscitation including airway management. However, the type of tier response system and airway management will have different interactive effects resulting in varying outcomes following out-of-hospital cardiac arrest (OHCA). This study aimed to determine whether the advanced airway management method has an effect on OHCA outcomes and to compare the size of the effect across MTR types. METHODS: This is a retrospective population-based observational study using the Korea OHCA Registry. Airway management methods were categorized into endotracheal intubation (ETI) and supraglottic airway (SGA) groups. The tier system was categorized into single-tier response (STR) or two types of MTR: ambulance-ambulance MTR or fire engine-ambulance MTR. RESULTS: In total, 45,264 patients were analyzed among the 89,087 emergency medical service assessed OHCAs. The SGA group was significantly associated with a lower prehospital return of spontaneous circulation (ROSC) rate compared to the ETI group (adjusted odds ratio [aOR], 0.79; 95% confidence interval [CI], 0.72–0.88). Both MTR with an ambulance or fire engine were significantly associated with higher prehospital ROSC rates compared to STR (STR vs. MTR with an ambulance: aOR, 1.33; 95% CI, 1.21–1.47; STR vs. MTR with a fire engine: aOR, 1.43; 95% CI, 1.20–1.71). Prehospital SGA was significantly associated with poor neurological outcomes in MTR with fire engine (aOR, 0.71; 95% CI, 0.53–0.96). CONCLUSION: In this nationwide observational study, we observed that MTR was associated with higher prehospital ROSC than STR. Moreover, SGA is associated with a lower prehospital ROSC rate regardless of tier response type compared to ETI.