Abstract 318: Association Carbon Dioxide Level During Cardiopulmonary Resuscitation with Neurological Outcome After Out-of-hospital Cardiac Arrests

Abstract

Background: Little evidence exists to guide appropriate ventilation strategies during CPR. We aimed to investigate the association between carbon dioxide (CO2) pressure measured on hospital arrival from those who were receiving ongoing resuscitation and neurological outcome after out-of-hospital cardiac arrest (OHCA). Method: This nationwide hospital-based prospective observational study (The JAAM-OHCA registry) carried out between June, 2014 and December, 2017 in Japan. From this registry, we included adult OHCA patients aged ≥18 years with blood gas sampled on hospital arrival during CPR. The main exposure was CO2 level in blood gas analysis during CPR. Based on the CO2 level on hospital arrival, included patients were classified into four quartiles (Q1-Q4) defined as Q1 (<66.0 mmHg), Q2 (66.1-87.2 mmHg), Q3 (87.3-113.5 mmHg), and Q4 (≥113.6 mmHg). The primary outcome of this study was one-month survival with favorable neurological outcome defined by cerebral performance category 1 or 2. We adjusted for potential confounders with multivariable logistic regression analysis. Results: During the study period, a total of 21,137 patients were included in our analysis. The overall proportion of favorable neurological outcome was 1.0% (207/21137). The highest proportion of favorable neurological outcome was observed in the Q1 group (2.4% [140/5244]), followed by Q2 (0.7% [37/5284]), Q3 (0.4% [21/5296]), and Q4 (0.2% [9/5313]). In the multivariable logistic regression analysis, we found that the Q4 group had the significantly lower proportion of favorable neurological outcome than the Q1 group (adjusted odds ratio 0.25; 95% confidence interval 0.16-0.55). The adjusted probability of favorable neurological outcome decreased in a stepwise fashion across increasing quartiles (P<0.001). Conclusion: This study observed the association between lower CO2 level on hospital arrival and favorable neurological outcome after OHCA in a dose-dependent manner.