Veno-arterial CO2 difference and respiratory quotient after cardiac arrest: An observational cohort study

Purpose: To characterize venous-arterial CO2 difference (Delta pCO(2)) and the respiratory quotient (RQ) in post cardiac arrest patients and evaluate the association between these parameters and patient outcome.Materials and Methods: Data were obtained retrospectively from post cardiac arrest patients admitted between 2007 and 2016 to a medical intensive care unit. Comatose, adult patients in whom arterial and venous blood gas analyses were concomitantly performed in the first 24 h were included. Patients were grouped according to the time-point of sampling; 0-6, 6-12 and 12-24 h after admission.Results: 308 patients were included; 174 (56%) died before ICU discharge and 212 (69%) had an unfavorable neurologic outcome. RQ was associated with ICU mortality (OR:1.09 (95%CI: 1.04-1.14; p< 0.01)), although not with neurological outcome. Delta pCO(2) was negatively associated with both ICU mortality (OR: 0.92 (95%CI: 0.86-0.99; p = 0.02)) and poor neurologic outcome (adjusted OR: 0.93 (95%CI: 0.87-0.99; p = 0.02)). Delta pCO(2) predicted an elevated RQ; a Delta pCO(2) above 8.5 mmHg identified a high RQ with reasonable sensitivity and specificity.Conclusions: RQwas associated with ICU mortality and Delta pCO(2) identified elevated RQ in the early phase after cardiac arrest. However, Delta pCO(2) were negatively associated with both ICU mortality and neurologic outcome. (C) 2020 Elsevier Inc. All rights reserved.