ORIGINAL RESEARCH article
Front. Med.
Sec. Intensive Care Medicine and Anesthesiology
Carbon Dioxide Combining Power as a Predictor of Unplanned ICU Transfer in Hospital Wards: A Retrospective Cohort Study
Provisionally accepted
- 1International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- 2Affiliated Hospital Department of Intensive Care Unit,, Jiujiang University Medical College, Jiujiang, China
- 3Jiujiang Third People's Hospital, jiujiang, China
- 4Department of Clinical Medicine, Jiujiang University Medical College, Jiujiang, China
Select one of your emails
You have multiple emails registered with Frontiers:
Notify me on publication
Please enter your email address:
If you already have an account, please login
You don't have a Frontiers account ? You can register here
Background: Unplanned intensive care unit (ICU) transfers are associated with high mortality. Conventional early warning scores like modified Early Warning Score (MEWS) show limited predictive ability. Carbon dioxide combining power (CO₂CP), a routine acid-base parameter, may enable earlier detection of clinical deterioration. Objective: To evaluate CO₂CP as a predictor of mortality in unplanned ICU transfers and assess its additive value to traditional scoring systems. Methods: This single-center retrospective study analyzed 101 adults with unplanned ICU transfers (Feb 2024-Jun 2025). CO₂CP levels within 8 hours pre-transfer, MEWS, and APACHE II scores were collected. Primary outcome was ICU mortality. Analyses included ROC curves, survival analysis, multivariable logistic regression, decision curve analysis, and correlation assessment. Results: The area under the ROC curve (AUC) for CO₂CP was 0.722 (95% CI: 0.615–0.829), higher than that of MEWS (AUC = 0.528, p = 0.040). Bootstrap validation yielded an AUC of 0.723 (95% CI: 0.581–0.849), indicating relative stability. Survival analysis showed poorer outcomes in patients with lower CO₂CP (log-rank P = 0.003). In multivariable analysis, CO₂CP remained independently associated with mortality (OR ≈ 0.87 per 1 mmol/L increase, p < 0.001), although the effect size was modest. The combined CO₂CP-MEWS model demonstrated good discriminatory ability, although its clinical utility requires further confirmation. Conclusion: CO₂CP may serve as an independent predictor of mortality risk in unplanned ICU transfers. Its integration with MEWS may enhance early risk stratification in general wards, though these findings require validation in larger prospective studies.
Keywords: Carbon dioxide combining power, Hospital wards, Intensive Care Unit, Mortality, Predictive Value, Retrospective cohort study
Received: 18 Oct 2025; Accepted: 19 Nov 2025.
Copyright: © 2025 Li, luo, zhao, du, Hu and Wu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Li Li, lilidaibaoli@163.com
Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.