Abstract Body: Background: Airway opening index (AOI) characterizes EtCO₂ distortions from chest compressions. We sought to determine the associations between AOI and OHCA outcomes in the Pragmatic Airway Resuscitation Trial (PART).
Methods: We performed a secondary analysis of data from PART, which evaluated advanced airway strategies in patients with OHCA. We included all cases with recorded EtCO₂ waveforms and active chest compressions. We calculated AOI summarized into 1-minute (min) epochs using 4 methods per ventilation: AOI1) (Max-Median EtCO₂)/ Max EtCO₂; AOI2) (Median-Trough EtCO₂)/Median EtCO₂; AOI3) (Max-Trough EtCO₂)/ Max EtCO₂; AOI4) (Max-Trough EtCO₂)/Median EtCO₂. We compared AOI in cases with ROSC versus (vs.) non-ROSC using the Mann-Whitney test. We repeated the analysis comparing 72-hour survival vs non-survivors. We also stratified ROSC analysis by witnessed status, shockable rhythm and advanced airway strategy.
Results: The PART trial enrolled 3004 patients, which included 1106 with EtCO₂ and chest compressions recorded. The latter were primarily male (62.3%), of white race (53.5%) with a non-shockable (84.7%) and nonpublic arrest (89.7%). ROSC occurred in 17.2%. AOI1 to AO4 methods all found similar results (Figure 1). AOI was lower in ROSC than non-ROSC cases (AOI4: ROSC 11.3 IQR 6.5-20.7 vs non-ROSC 13.8 IQR 7.8-25.5; p<0.01). AOI was similarly lower in cases surviving to 72-hours. AOI was lower in ROSC cases that were bystander witnessed (p<0.01), with bystander CPR (p<0.01), in shockable initial rhythms (p<0.01) or with laryngeal tube placement (p<0.01). AOI was not different between ROSC and non-ROSC in unwitnessed, without bystander CPR or endotracheal intubated cases.
Conclusions: In this analysis, AOI was lower in patients with ROSC and 72-hour survival.