4. Discussion
re-sedation, emesis, pain
ADVERSE EVENTS
This study showed that the time to extubation, eye opening, obeying commands, and achieving a WFTS score of 12 were all significantly shorter under remimazolam-based anesthesia with flumazenil than under propofol-based anesthesia in older patients who underwent spinal surgery. There were no prolonged extubation (defined as 15 minutes or longer)Extubation time is an important factor in emergence from general anesthesia. Prolonged extubation decreases OR efficiency, including case turnover and use of OR time, and increases variable OR costsThe type of anesthetic used can affect the time of emergence. Remimazolam is a short-acting benzodiazepine that acts on gamma-aminobutyric acid (GABA)Both anesthetics are short-acting; however, remimazolam is less accumulative. Notably, the GABAergic effects of remimazolam can be antagonized by flumazenil. This suggested that remimazolam can provide a more rapid emergence than propofol, which does not antagonize antidotes. However, remimazolam anesthesia takes longer to emerge than propofol anesthesia.The emergence status was assessed using the WFTS. We have no post-anesthesia care unit, and take patients from the OR directly to the less extensively monitored wards. Therefore, we used the white fast-track scoring system incorporating the evaluation of emesis and pain in the modified Aldrete scoring system. This is commonly used for discharge criteria from the post-anesthesia care unit to postsurgical wards, to measure the ability for discharge from the OR.In spinal surgery with MEP monitoring, the influence of benzodiazepines on MEP is considered similar to that of propofol. Although studies on remimazolam are few, they are unlikely to interfere with MEP monitoring.This study had several limitations. First, remimazolam and propofol were adjusted based on electroencephalogram monitoring; however, minimal doses of both anesthetics were not established. We did not excessively reduce the dose to avoid intraoperative arousal. Therefore, it is possible that both propofol and remimazolam could have been further reduced.Second, flumazenil (0.5 mg) was administered simultaneously as the discontinuation of anesthetic administration in all patients; however, an adequate dose and timing for flumazenil administration have not yet been established. There have been reports that 0.2–0.4 mg flumazenil administration following remimazolam anesthesia in older patients undergoing transcatheter aortic valve implantation did not cause re-sedation, and that 0.5 mg flumazenil administered immediately after remimazolam anesthesia did not cause any adverse events. In this study, we set up a 0.5 mg single-dose flumazenil protocol based on these reports.In conclusion, we investigated the state of emergence from remimazolam-based anesthesia in the older patients > 75 years old who underwent spinal surgery. This study showed that remimazolam-based anesthesia with flumazenil resulted in a significantly faster emergence than propofol-based anesthesia.