In the present study, the times from discontinuation of volatile anesthetics to eye opening, hand squeezing, tracheal extubation, and orientation to the patients’ full name, date, and place were significantly shorter in the desflurane group than in the sevoflurane group. The times to orientation to the date and place were less variable in the desflurane group than in the sevoflurane group. These findings support our hypothesis that changing the anesthetic agent from sevoflurane to desflurane improves emergence and recovery from general anesthesia, even after sevoflurane induction.
Previous studies in children have reported faster emergence with desflurane than with sevoflurane after volatile induction with sevoflurane.16,17 Our results are consistent with these findings despite the fact that these previous studies differed in their use of nitrous oxide for anesthesia induction and maintenance. Nevertheless, few studies have compared anesthesia emergence times between desflurane and sevoflurane after volatile induction in adults. Furthermore, it is unknown whether changing the anesthetic agent from sevoflurane to desflurane improves the recovery profile after general anesthesia. This is most likely due to the young age of the participants in prior studies, which prevented precise measurements of recovery times.16,17 The times in our study from discontinuation of volatile anesthetics to orientation to the patients’ full name, date, and place were significantly shorter in the desflurane group than in the sevoflurane group, which suggests that changing from sevoflurane to desflurane permits faster recovery than sevoflurane anesthesia, even after sevoflurane induction. In addition, the time trend in recovery events differed between the two groups. The time intervals between tracheal extubation and orientation to the patients’ full name were similar (1 min in the sevoflurane group vs 1.3 min in the desflurane group). Nevertheless, the times between tracheal extubation and orientation to the date and place were longer in the sevoflurane group (5.4 min and 4.6 min, respectively) than in the desflurane group (2.4 min and 2.4 min, respectively). These results indicate that maintenance with sevoflurane delays orientation to the date and place after tracheal extubation compared with maintenance with desflurane. Additionally, the times to orientation to the date and place were less variable in the desflurane group, suggesting that changing from sevoflurane to desflurane provides more predictable recovery compared with sevoflurane anesthesia. Patients’ rapid and predictable recovery after desflurane anesthesia in our study is consistent with previous studies,8,18 and our findings show that volatile induction with sevoflurane does not alter the favourable pharmacological characteristics of desflurane. The rapid and predictable recovery that results from changing from sevoflurane to desflurane may improve patient turnover in the operating room and may be cost-effective.8
Previous studies have attempted to combine the advantages of different volatile anesthetics. Several studies have investigated the effects of changing from isoflurane to desflurane during the latter part of anesthesia,19-21 and Kang et al. have reported that changing from enflurane to desflurane effectively improved recovery from general anesthesia.22 Nevertheless, few studies have reported the advantages of changing from sevoflurane to desflurane. In the present study, none of the patients experienced severe adverse events during volatile induction, and changing from sevoflurane to desflurane provided fast emergence and recovery. Therefore, this technique can achieve both smooth induction and rapid recovery without pain on intravenous catheter insertion or injection of intravenous anesthetics such as propofol.
In the present study, there were no significant differences in PONV scores between the sevoflurane group and the desflurane group, which is consistent with previous studies.23,24 Eye pain scores did not differ significantly between the groups in our study, which is also in accordance with previous studies.25,26 These results suggest that there are no significant differences in the degree of PONV or postoperative pain between patients receiving sevoflurane or desflurane.
Interestingly, five patients in the sevoflurane group complained of a postoperative unpleasant breath odour at the 24-hr postoperative interview, whereas only one patient in the desflurane group reported an unpleasant odour. The odour was likely caused by sevoflurane, as all the patients who complained of this odour noticed the presence of a similar odour during volatile induction. These results can be attributed to the slower elimination kinetics of sevoflurane compared with desflurane.27,28 Although there was no significant difference between groups on the 100-mm VAS satisfaction question on anesthesia, postoperative breath odour may be unpleasant for patients.
In this changing technique from sevoflurane to desflurane, the patients’ awareness during the changing period may concern anesthesiologists. The BIS never exceeded 60 during the changing period in the desflurane group; awareness during anesthesia is unlikely when the BIS is < 60.29,30 Furthermore, none of the patients experienced awareness during anesthesia, suggesting that changing from sevoflurane to desflurane during the early part of anesthesia does not cause awareness during the changing period. The low solubility of desflurane may provide faster wash-in compared with the wash-out of sevoflurane, maintaining an adequate depth of anesthesia during the changing period.31 Nevertheless, the gas analyzer may not always indicate accurate concentrations of volatile anesthetics when more than one agent is present; therefore, the use of a BIS monitor is recommended when changing from sevoflurane to desflurane.
Our study has several limitations. First, we did not attempt to decrease the anesthetic dose until discontinuation of the volatile anesthetic after surgery. Titration of the anesthetic concentration to achieve a higher BIS (e.g., 55 or 60) towards the end of surgery may affect the times for emergence and recovery. Second, we did not administer opioids except for remifentanil, an ultra-short-acting opioid.32 Additionally, the continuous infusion of remifentanil was discontinued at least ten minutes before Time 0 to minimize its influence on emergence and recovery. The administration of longer lasting opioids, such as fentanyl and alfentanil, or remifentanil immediately before the end of surgery may affect the efficacy of the changing technique.33,34 Third, regarding the recovery from anesthesia, we assessed only the early recovery, such as the times to orientation to the patients’ full name, date, and place. Further studies of late recovery, such as the times to discharge from the hospital and full normal activity, are necessary to evaluate the long-term effects of the changing technique on the recovery profile.
In conclusion, we found that changing the anesthetic agent from sevoflurane to desflurane after volatile induction with sevoflurane provides faster emergence and recovery compared with sevoflurane anesthesia. This changing technique allows for both smooth induction and rapid recovery, achieving high patient satisfaction.