The following is a summary of “Association between rate of change in PaCO2 and functional outcome for patients with hypercapnia after out-of-hospital cardiac arrest: Secondary analysis of a randomized clinical trial,” published in the March 2023 issue of Emergency Medicine by Zhou, et al.
In post-resuscitation care, normocapnia is recommended. However, the relationship between the rate of change in partial pressure of carbon dioxide (PaCO2) and functional outcomes for patients with hypercapnia after cardiac arrest was not clear.
The study was a secondary analysis of the Resuscitation Outcomes Consortium (ROC) amiodarone, lidocaine, and placebo (ALPS) trial. It included patients who had at least 2 PaCO2 recorded and the first PaCO2 indicating hypercapnia (PaCO2 > 45 mmHg) after the return of spontaneous circulation (ROSC). The rate of change in PaCO2 was calculated as the difference between the second and first PaCO2 divided by the time interval. The primary outcome was the modified Rankin Score (mRS) at hospital discharge, which was categorized as good (mRS 0-3) or poor (mRS 4-6). The study investigated the independent relationship between the rate of change in PaCO2 and functional outcome using a multivariable logistic regression model.
The analysis included 746 patients with hypercapnia, of which 264 (35.4%) had a good functional outcome. The median rate of change in PaCO2 was 4.7 (interquartile range [IQR] 1.7–12) mmHg per hour. After adjusting for confounders, the rate of change in PaCO2 was not significantly associated with functional outcome (odds ratio [OR] 0.994, CI 0.985–1.004, P = 0.230). However, the rate of change in PaCO2 was independently associated with hospital mortality (OR 1.010, CI 1.001–1.019, P = 0.029), indicating that a higher decrease in the rate of change in PaCO2 was associated with increased hospital mortality.
The rate of change in PaCO2 was not independently associated with functional outcomes for patients with hypercapnia after cardiac arrest, but a higher decrease in the rate of change in PaCO2 was associated with increased hospital mortality.
Reference: sciencedirect.com/science/article/pii/S0735675723000074