Intraoperative reliability of end-tidal CO2 during elective craniotomy: Temporal changes in the PaCO2–PETCO2 gradient
Makaleler > Tam Makale · 2026
Yazarlar: Kilercik, Hakan, Balcıoğlu, Sacittin Taner
Developments and Experiments in Health and Medicine, Vol. 40 No. 3, Uluslararası, 2026
Özet
Background: Precise regulation of arterial carbon dioxide tension (PaCO2) is essential in neuroanesthesia, because even minor fluctuations can directly influence cerebral perfusion and intracranial dynamics. Despite its widespread use as a non-invasive surrogate, the accuracy of end-tidal carbon dioxide (PETCO2) in reflecting arterial CO₂ is still debated. The present study aimed to evaluate the level of concordance between PaCO2 and PETCO2, and to assess temporal changes in the arterial-to-end-tidal carbon dioxide [P(a–ET)CO2] gradient during craniotomy. Methods: In this prospective observational study, 23 patients undergoing elective craniotomy were included. Simultaneous PaCO2 and PETCO2 measurements were obtained at three predefined intraoperative time points: post-induction, post-craniotomy, and at the beginning of dural closure. Temporal changes were analyzed using repeated-measures statistics, and agreement was assessed with Bland–Altman analysis. Results: PaCO2 increased significantly over time (p = 0.005), whereas PETCO2 remained stable (p = 0.376). Consequently, the P(a–ET)CO2 gradient widened significantly (p = 0.030). Bland–Altman analysis demonstrated a progressive increase in mean difference between PaCO2 and PETCO2 (from 0.89 to 2.89 mmHg), indicating reduced agreement over time. Conclusion: Our findings suggest that the P(a–ET)CO2 gradient widens over time during prolonged craniotomy, indicating that the reliability of PETCO2 as a direct substitute for PaCO2 may diminish over time. Therefore, PETCO2 should be interpreted with caution, ideally as a trend monitor rather than an absolute indicator. Periodic arterial blood gas analysis remains essential for accurate CO2 management, particularly during prolonged procedures.