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