Alveolar Ventilation Efficiency Assessed via Capnography is Associated with Improved Outcomes in Pediatric Cardiac Arrest.

RATIONALE: Airway opening index (AOI) is a metric recently described in adults to infer airway patency during cardiopulmonary resuscitation (CPR). The underlying premise is that higher AOI values suggest more patent airways, which leads to improved ventilation/ outcomes. OBJECTIVES: 1) To quantitatively describe AOI during pediatric CPR and 2) to evaluate the association of AOI with outcomes. METHODS: Prospective multicenter observational cohort study of children (≤18 years) with invasive airways and capnography data. 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]). Cubic splines/ receiver operating characteristic curves identified an AOI cutpoint for evaluation in modified Poisson regression models. A sensitivity analysis excluded extracorporeal CPR patients (E-CPR). MEASUREMENTS: The primary outcome was survival to hospital discharge. MAIN RESULTS: Among 99 events (median age: 0.34 [0.04, 3.26] yrs), median AOI was 0.38 [0.25, 0.53]. Event-level average AOI ≥0.35 was associated with improved survival to hospital discharge (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 AOI <0.35. Findings were robust when excluding E-CPR patients. After return of circulation, events with AOI ≥0.35 had lower peak arterial lactates (6.0 [2.8, 11.0] vs. 11.5 [6.4, 19.0] mmol/L, p = 0.006), 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 outcomes. Events with AOI ≥0.35 had evidence of improved post-arrest physiology.