Skip to main content
Open Access Publications from the University of California

Impact of stepwise hyperventilation on cerebral tissue oxygen saturation in anesthetized patients: A mechanistic study

  • Author(s): Alexander, BS
  • Gelb, AW
  • Mantulin, WW
  • Cerussi, AE
  • Tromberg, BJ
  • Yu, Z
  • Lee, C
  • Meng, L
  • et al.

Published Web Location Commons Attribution 4.0 International Public License

Background: While the decrease in blood carbon dioxide (CO2) secondary to hyperventilation is generally accepted to play a major role in the decrease of cerebral tissue oxygen saturation (SctO2), it remains unclear if the associated systemic hemodynamic changes are also accountable. Methods: Twenty-six patients (American Society of Anesthesiologists I-II) undergoing nonneurosurgical procedures were anesthetized with either propofol-remifentanil (n = 13) or sevoflurane (n = 13). During a stable intraoperative period, ventilation was adjusted stepwise from hypoventilation to hyperventilation to achieve a progressive change in end-tidal CO2 (ETCO2) from 55 to 25 mmHg. Minute ventilation, SctO2, ETCO2, mean arterial pressure (MAP), and cardiac output (CO) were recorded. Results: Hyperventilation led to a SctO2 decrease from 78 ± 4% to 69 ± 5% (D =-9 ± 4%, P < 0.001) in the propofolremifentanil group and from 81 ± 5% to 71 ± 7% (D =-10 ± 3%, P < 0.001) in the sevoflurane group. The decreases in SctO 2 were not statistically different between these two groups (P = 0.5). SctO2 correlated significantly with ETCO2 in both groups (P < 0.001). SctO2 also correlated significantly with MAP (P < 0.001) and CO (P < 0.001) during propofol-remifentanil, but not sevoflurane (P = 0.4 and 0.5), anesthesia. Conclusion: The main mechanism responsible for the hyperventilation-induced decrease in SctO2 is hypocapnia during both propofol-remifentanil and sevoflurane anesthesia. Hyperventilation-associated increase in MAP and decrease in CO during propofol-remifentanil, but not sevoflurane, anesthesia may also contribute to the decrease in SctO2 but to a much smaller degree. © 2013 The Acta Anaesthesiologica Scandinavica Foundation Published by Blackwell Publishing Ltd.

Many UC-authored scholarly publications are freely available on this site because of the UC Academic Senate's Open Access Policy. Let us know how this access is important for you.

Main Content
Current View