The sevoflurane concentration for light sedation in critically ill patients: A protocol for experimental study

Background: Deep-inhaled sedation is increasingly used in Thai ICUs. However, there is a lack of information regarding the level of end-tidal sevoflurane concentration during light sedation. Objectives: The study aims to determine the effective dose (ED50 and ED95) of sevoflurane concentration for light sedation (RASS score -1 to 0) in mechanically ventilated critically ill patients. Methods: This is a prospective experimental single-center study. Mechanically ventilated patients with RASS ≥ 1 who required sedation in the medical and surgical intensive care unit were enrolled. Using an up-and-down sequential allocation technique, the inhaled sevoflurane level of each patient was allocated based on the previous patient’s response. RASS score and hemodynamic parameters were monitored. The primary outcome was the ED50 and ED 95 of end-tidal sevoflurane concentration. The secondary outcomes included the length of intensive care unit stay, duration of ventilator day, the incidence of delirium, hemodynamic status, and respiratory variables changed during the study period. Hypothesis: There exist specific end-tidal sevoflurane concentrations (ED50 and ED95) that will reliably induce a target RASS score of -1 to 0 in critically ill patients who are mechanically ventilated. Conclusion: This study will provide an effective dose of inhaled sevoflurane sedation for achieving targeted light sedation levels in critically ill patients, which may have minimal effects on hemodynamics. Ethics and dissemination: This study has been approved by the Office of Human Research Ethics Committee, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Thailand, on 22nd May 2023 (COA.MURA2023/390). Trial registration: TCTR20230825001