Perioperative medicine & outcomes
Association of intraoperative end-tidal CO2 levels with postoperative outcomes: a patient-level analysis of two randomised clinical trials
Primary resultResult — go to the resultAdjusted hazard ratio 1.3 95% CI 1.1–1.6Authors' conclusion
Low etCO2 occurs often during intraoperative ventilation and is associated with a higher rate of PPCs. The etCO2 level has an inverse dose-dependent relationship with postoperative pulmonary complications.
Study context
- Population
- Adults undergoing major surgery under GA (non-obese and obese)
- Participants
- 891 vs 1,972
- Comparison
- Low end-tidal CO2 (etCO2) vs normal-high etCO2
- Low etCO2n = 891
- Normal-high etCO2n = 1,972reference
- Primary endpoint
- Postoperative pulmonary complications
- Follow-up
- Within 5 days
Methodological detailsPROVHILO and PROBESE, individual participant data, time-weighted analysis, propensity score matching
- PROVHILO and PROBESE
- Individual participant data
- Time-weighted analysis
- Propensity score matching
Primary result
As reported in the abstract
Adjusted hazard ratio
1.3
95% CI 1.1–1.6
P < 0.001
Events by treatment group
Low etCO2 vs Normal-high etCO2
aHR 1.3 (95% CI 1.1–1.6); P < 0.001
Further findings
Time-weighted mean etCO2 and PPCs
- Inverse linear relationship between mean etCO2 and PPCs, confirmed by propensity matching
Minute volume (normalised to body weight)
- Higher minute volumes delivered in low etCO2 vs normal-high etCO2
Parts of this Brief are withheld: the automatic checks could not confirm them against the abstract.
Original publication
Association of intraoperative end-tidal CO2 levels with postoperative outcomes: a patient-level analysis of two randomised clinical trials. Br J Anaesth. Published 10 September 2025. doi:10.
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