Out-of-hospital airway management and cardiac arrest outcomes: a propensity score matched analysis

Objective: It is unclear whether advanced airway management during ambulance transport is associated with improved out-of-hospital cardiac arrest (OHCA) outcomes compared with bag-valve mask ventilation (BVM). This study aimed to determine whether EMT-intermediate ETI or LMA is associated with improved OHCA outcomes in Korea.

Methods: We used a Korean national OHCA cohort database composed of hospital and ambulance data. We included all EMS-treated by level 1 EMTs (EMT-intermediate level) and OHCA with presumed cardiac etiology for the period January 2006-December 2008. We excluded cases not receiving continued resuscitation in the emergency department (ED), treated by level 2 EMT, as well as those without available hospital outcome data. The primary exposure was airway management technique during ambulance transport (endotracheal tube (ETI), laryngeal mask airway (LMA) or bag-valve-mask ventilation with an oropharyngeal airway). The primary outcomes were survival to admission and survival to hospital discharge. We compared outcomes between each airway management group using multivariable logistic regression, adjusting for sex, age, witnessed, prehospital defibrillation, bystander cardiopulmonary resuscitation (CPR), call to ambulance arrival time to the scene, call to ambulance arrival time to ED, initial ECG, metropolitan (defined as population>1 million), and level of ED (higher versus lower level). We repeated the analysis using propensity-score matched subsets.

Results: Of 54,496 patients with OHCA, we included 5278 (9.7%). Overall survival to admission and to discharge was 20.2% and 6.9%, respectively. ETI and LMA were performed in 250 (4.7%) and 391 (7.4%), respectively. In the full multivariable models using total patients, adjusted survival to admission and discharge were similar for ETI and BVM: OR 0.91 (0.66-1.27) and 1.00 (0.60-1.66), respectively. Adjusted survival to admission and discharge were significantly lower in LMA than BVM: OR 0.72 (0.54-0.95) and 0.52 (0.32-0.85), respectively. In the full multivariable models using propensity matched samples, adjusted survival to admission and discharge were similar for ETI and BVM; OR 1.32 (0.81-2.16) and 1.44 (0.66-3.15), respectively. Adjusted survival to admission was similar for LMA and BVM: OR 0.72 (0.50-1.02). However, survival to discharge was significantly lower for LMA than BVM: OR 0.45 (0.25-0.82).

Conclusions: In Korea, EMT-I placed LMA during ambulance transport was associated with worsened OHCA survival to discharge than BVM. Outcomes were similar between EMT-I endotracheal intubation and bag-valve-mask ventilation.