Inhalation sedation for postoperative patients in the intensive care unit: initial sevoflurane concentration and comparison of opioid use with propofol sedation

Background: Although the use of volatile sedatives in the intensive care unit (ICU) is increasing in Europe, it remains infrequent in Asia. Therefore, there are no clinical guidelines available. This study investigates the proper initial concentration of sevoflurane, a volatile sedative that induces a Richmond agitation-sedation scale (RASS) score of -2 to -3, in patients who underwent head and neck surgery with tracheostomy. We also compared the amount of postoperative opioid consumption between volatile and intravenous (IV) sedation. Methods: We planned a prospective study to determine the proper initial sevoflurane concentration and a retrospective analysis to compare postoperative opioid consumption between volatile sedation and propofol sedation. Patients scheduled for head and neck surgery with tracheostomy and subsequent postoperative sedation in the ICU were enrolled. Results: In this prospective study, the effective dose 50 (ED50) of initial end-tidal sevoflurane concentration was 0.36% (95% confidence interval [CI], 0.20 to 0.60%), while the ED 95 was 0.69% (95% CI, 0.60 to 0.75%) based on isotonic regression methods. In this retrospective study, remifentanil consumption during postoperative sedation was significantly lower in the sevoflurane group (2.52 +/- 1.00 mu g/kg/hr, P=0.001) than it was in the IV propofol group (3.66 +/- 1.30 mu g/kg/hr). Conclusions: We determined the proper initial end-tidal concentration setting of sevoflurane for patients with tracheostomy who underwent head and neck surgery. Postoperative sedation with sevoflurane appears to be a valid and safe alternative to IV sedation with propofol.