Neuroanaesthesia & neurocritical care
Arterial-to-end-tidal carbon dioxide gradient as a risk marker for recorded 90-day mortality in intracranial neurosurgery: a retrospective INSPIRE cohort study of patients with early blood gas monitoring
Main finding · Database-recorded all-cause death (revised principal association model: clinical covariates and contemporaneous mean arterial pressure, heart rate and minute ventilation)Result — go to the resultOdds ratio 1.34 95% CI 1.06–1.69Authors' conclusion
A larger first-hour gradient was associated with recorded mortality in patients selected for early paired monitoring. Within the evaluated models and metrics, incremental prediction was limited. These findings do not establish a causal mechanism, treatment target or externally validated prediction tool.
Study context
- Population
- Adults undergoing their first eligible intracranial operation with arterial carbon dioxide tension (PaCO₂) recorded within 60 min of anesthesia start, with end-tidal carbon dioxide (ETCO₂) paired within ±5 min; INSPIRE v1.4.2, surgery from 2011 to 2020patients, 95 deaths recorded
- Participants
- 1,907 adults
- Exposure
- First-hour arterial-to-end-tidal carbon dioxide gradient (per 5 mmHg) as a marker of recorded 90-day mortality
- Outcome
- Database-recorded all-cause death (revised principal association model: clinical covariates and contemporaneous mean arterial pressure, heart rate and minute ventilation)
- Follow-up
- 90 days
Main finding
As reported in the abstract
Odds ratio
1.34
95% CI 1.06–1.69
Arterial-to-end-tidal carbon dioxide gradient
OR 1.34 (95% CI 1.06–1.69)
Observational data: associations, not effects.
Further findings
| Outcome | OR (per 5 mmHg) (95% CI) | |
|---|---|---|
| Recorded 90-day mortality, clinical gradient model | 1.38 (1.09–1.73) | |
| 0.512Odds ratio (log scale) |
Conditional component estimates (secondary)
- Did not establish predominance of either component
Incremental prediction: adding the gradient to clinical variables, contemporaneous physiology and ETCO₂ (optimism-corrected area under the curve)
- Area under the curve without the gradient
- 0.832
- Area under the curve with the gradient
- 0.833
- Brier score not improved
- Internally validated
Original publication
Arterial-to-end-tidal carbon dioxide gradient as a risk marker for recorded 90-day mortality in intracranial neurosurgery: a retrospective INSPIRE cohort study of patients with early blood gas monitoring. J Clin Anesth. Published 13 October 2026. doi:10.
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