SynthesisCritical care (London, England)2026
Association of mortality and neurological outcomes with hypocapnia in adult patients with acute brain injury: an updated meta-analysis.
Synthesis in Critical care (London, England), 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
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11 authors.
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Abstract
backgroundCarbon dioxide is a key determinant of cerebral blood flow and is needed to prevent secondary damage in neurocritical care; however, optimal targets across the heterogeneous spectrum of acute brain injury (ABI) remain to be elucidated. The aim of this study was to evaluate the association between arterial hypocapnia and mortality and neurological outcomes in adult patients with ABI.
methodsSix electronic databases were systematically searched from inception to January 2025. Observational and randomized controlled trials comparing exposure to hypocapnia, defined as an arterial partial pressure of carbon dioxide (PaCO
resultsA total of 8,637 records were identified after duplicate removal, of which 37 studies met inclusion criteria for the systematic review. Twenty-seven studies (51,373 patients) were included for mortality outcomes, and thirteen studies (3,814 patients) were included for neurological outcomes. Hypocapnia was associated with higher odds of mortality in adult patients with ABI (OR 1.29, 95% CI 1.05-1.59). Subgroup analyses demonstrated variability across ABI types, with stronger associations observed in subarachnoid hemorrhage and ischemic stroke populations. Hypocapnia was also associated with increased odds of poor neurological outcomes (OR 2.09, 95% CI 1.24-3.54), particularly in the traumatic brain injury population. Subgroup analyses suggested that the association with neurological outcomes was more consistent in studies defining exposure as severe hypocapnia (PaCO
conclusionsArterial hypocapnia was associated with increased mortality and poor neurological outcomes in adults with acute brain injury, although the evidence is predominantly observational and limited randomized data are available. These findings underscore the need for cautious, individualized PaCO
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