# Carbon dioxide elimination as a guide to venoarterial extracorporeal membrane oxygenation weaning: a prospective observational study

## TL;DR

This study shows that carbon dioxide elimination parameters can predict successful weaning from VA-ECMO in patients with cardiogenic shock.

## Contribution

The study identifies EtCO2 and VCO2NL ratio as novel predictors for successful VA-ECMO weaning.

## Key findings

- EtCO2 and VCO2NL ratio are significantly correlated with successful VA-ECMO weaning.
- A VCO2NL ratio >79% and EtCO2 >34 mmHg strongly predict successful weaning.
- The predictive performance has high area under the ROC curve values (0.85 and 0.84).

## Abstract

Despite the increasing use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) in cardiogenic shock (CS), reliable predictors of successful weaning remain poorly defined. This study investigated the role of carbon dioxide elimination parameters in VA-ECMO weaning.

To assess the potential role of end-tidal carbon dioxide (EtCO2) in predicting successful VA-ECMO weaning, we conducted a prospective observational study at Anzhen Hospital between January 2023 and December 2024. The primary endpoint was the predictive performance of EtCO2 and VCO2NL ratio for successful VA-ECMO weaning. Real-time EtCO2 monitoring was performed using infrared capnography in mechanically ventilated patients, and the ratio of native lung carbon dioxide elimination (VCO2NL) to total carbon dioxide elimination (VCO2TOT) was calculated as the VCO2NL ratio. Dynamic changes in these parameters were analysed in relation to weaning outcomes. Among 294 patients receiving VA-ECMO for refractory CS during the study period, 91 were included, yielding 562 data points. Both EtCO2 (odds ratio [OR] = 1.26, 95% confidence interval [CI] 1.17–1.37, p < 0.0001) and the VCO2NL ratio (1.14, 95% CI 1.09–1.21, p < 0.0001) showed significant correlations with successful weaning. A VCO2NL ratio > 79% and EtCO2 > 34 mmHg showed strong predictive value for successful weaning (area under the receiver operating characteristics (ROC) curve values of 0.85 [95% CI 0.80–0.89] and 0.84 [95% CI 0.79–0.89], p < 0.0001).

EtCO2 and the VCO2NL ratio may be valuable indicators for predicting successful VA-ECMO weaning. Higher EtCO2 and VCO2NL ratio values are associated with a greater likelihood of successful weaning.

The online version contains supplementary material available at 10.1186/s13613-025-01583-4.