Abstract Body: Introduction: Pediatric cardiopulmonary resuscitation (CPR) guidelines provide primitive ventilation guidance (observe chest rise, target a ventilation rate). Calculated from capnography waveforms, airway opening index (AOI) is a metric recently described in adults to infer airway patency during CPR. AOI has not yet been associated with survival nor described in pediatric patients.
Aims: 1) To quantitatively describe AOI during pediatric CPR and 2) to evaluate the association of AOI with intra-/post-arrest physiology and outcomes.
Methods: This was a prospective multicenter observational cohort study. Children (≤18 years) with invasive airways and end-tidal carbon dioxide (ETCO₂) / arterial blood pressure (BP) data were included. AOI was calculated as the average of ((delta CO₂)/max CO₂) associated with each chest compression during a ventilation (range 0 [closed] to 1 [open/patent]). Cubic splines / receiver operating characteristic curves were used to identify an AOI target for evaluation in modified Poisson regression models (a priori covariates: age; cause of arrest; Pediatric RISk of Mortality score). A sensitivity analysis excluded extracorporeal CPR patients (E-CPR). The primary outcome was survival to hospital discharge (SHD). Secondary / exploratory outcomes included: other patient outcomes (e.g., favorable neurological outcome [Pediatric Cerebral Performance Category Score 1-3 or no change]) and intra- and post-arrest (6 hours after return of circulation [ROC]) physiology.
Results: Among 99 included events (median age: 0.34 [0.04, 3.26] yrs), median AOI was 0.38 (survivors: 0.45 [0.28, 0.61]; non-survivors: 0.30 [0.24, 0.48]; p=0.02). A target AOI of ≥0.35 was identified, which was associated with improved SHD (aRR 1.53 [CI95 1.03, 2.28], p=0.04) and favorable neurological outcome (aRR 1.56 [CI95 1.01, 2.41], p=0.04) compared to an AOI <0.35. During CPR, intra-arrest ETCO₂ was lower (-5.82 mmHg [CI95 -9.72, -1.91], p<0.01) in events with AOI ≥0.35. Findings were robust when excluding E-CPR patients. In the 6 hours after ROC, events with AOI ≥0.35 had lower peak arterial lactates (6.1 [3.2, 13.1] vs. 11.4 [5.4, 16.1] mmol/L, p=0.043), despite similar CPR durations (≥0.35: 9 [3, 36] vs. <0.35: 8.5 [3, 21] min, p=0.64).
Conclusions: In this multicenter study, an AOI ≥0.35 was associated with improved survival and favorable neurological outcome. Among events with AOI ≥0.35, there was evidence of improved immediate post-arrest physiology (lower lactates).