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Meta-Analysis
. 2025 May;44(3):101522.
doi: 10.1016/j.accpm.2025.101522. Epub 2025 Apr 24.

Association between arterial carbon dioxide tension and poor outcomes after cardiac arrest: A meta-analysis

Affiliations
Meta-Analysis

Association between arterial carbon dioxide tension and poor outcomes after cardiac arrest: A meta-analysis

Ru-Ting Xue et al. Anaesth Crit Care Pain Med. 2025 May.

Abstract

Background: Abnormal arterial carbon dioxide tension (PaCO2) is a common finding after cardiac arrest (CA). Inconsistent results regarding the association between abnormal PaCO2 and poor outcomes have been reported previously. We performed a meta-analysis to evaluate whether hypocapnia or hypercapnia is associated with an increased risk of hospital mortality and poor neurological outcomes in adult patients with CA.

Methods: PubMed, Embase, and the Cochrane Library databases were searched through October 2024 to determine studies investigating the association between PaCO2 and the risk of hospital mortality and/or poor neurological outcomes in adult patients with CA. A random-effects model was used to calculate the pooled odds ratio (OR) with 95% confidence intervals (CIs) for cohort studies and relative risks (RRs) with 95% CIs for randomized controlled trials (RCTs).

Results: A total of 14 cohort studies and 3 RCTs comprising 72344 patients were included. Pooled analysis indicated that hypocapnia was associated with an increased risk of hospital mortality (nine cohort studies, OR 1.37; 95% CI, 1.18-1.59; P < 0.0001) and poor neurological outcomes (five cohort studies, OR, 1.75; 95% CI, 1.04-2.96; P = 0.035). Within cohort studies, hypercapnia was associated with increased risk of hospital mortality (10 trials, OR 1.40; 95% CI, 1.13-1.73; P = 0.002), but not associated with poor neurological outcomes (six cohort studies, OR, 1.57; 95% CI, 0.87-2.83; P = 0.130). Within RCTs, mild hypercapnia was not associated with an increased risk of poor neurological outcomes after CA.

Conclusions: Current evidence indicated that hypocapnia was associated with an increased risk of hospital mortality and poor neurological outcomes after CA; however, hypercapnia was associated with an increased risk of hospital mortality but did not appear to be associated with increased poor neurological outcomes after CA.

Systematic review protocol: INPLASY 2024100120. Registered 28 October 2024.

Keywords: Hospital mortality; Hypercapnia; Hypocapnia; Meta-analysis; Neurological outcome.

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Conflict of interest statement

Declaration of competing interest The authors declare no competing interests.

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