Postanesthesia Care Unit Recovery Time According to Volatile Anesthetic Used in Clinical Practice

Whether volatile anesthetic solubility affects postanesthesia recovery time in clinical practice is unclear. We investigated the association among 3 volatile agents and 2 clinically relevant outcomes-postanesthesia care unit (PACU) recovery time (time from PACU admission to fulfillment of discharge criteria) and oversedation (Richmond Agitation-Sedation Scale score ≤-3)-as a potential contributor to delaying PACU discharge. The volatile agents studied were isoflurane, desflurane, and sevoflurane. We hypothesized that increased solubility of the volatile agent (isoflurane versus desflurane or sevoflurane) would be associated with longer PACU recovery time and higher rates of oversedation.

This retrospective observational study included adults (≥18 years) who underwent surgical procedures under general anesthesia with a volatile agent and were admitted to the PACU from May 5, 2018, to December 31, 2020. The primary outcome was PACU recovery time, and the secondary outcome was oversedation. PACU recovery time was log-transformed and analyzed with linear regression. Oversedation was analyzed by using logistic regression. To account for potential confounding, inverse probability of treatment weighting (IPTW) was used. Pairwise comparisons of the 3 agents were performed, with P < .017 (Bonferroni-adjusted) considered significant.

Of 47,847 patients included, 11,817 (24.7%) received isoflurane, 11,286 (23.6%) received desflurane, and 24,744 (51.7%) received sevoflurane. Sevoflurane had an estimated 4% shorter PACU recovery time (IPTW-adjusted median [interquartile range {IQR}], 61 [42-89] minutes) than isoflurane (64 [44-92] minutes) (ratio of geometric means [98.3% confidence interval {CI}], 0.96 [0.95-0.98]; P < .001). Differences in PACU recovery time between desflurane and the other agents were not significant. The IPTW-adjusted frequency of oversedation was 8.8% for desflurane, 12.2% for sevoflurane, and 16.7% for isoflurane; all pairwise comparisons were observed to be significant (odds ratio [98.3% CI], 0.70 [0.62-0.79] for desflurane versus sevoflurane, 0.48 [0.42-0.55] for desflurane vs isoflurane, and 0.69 [0.63-0.76] for sevoflurane versus isoflurane; all P < .001). Although oversedated patients had longer PACU recovery time, differences in the oversedation rate across agents did not result in meaningful differences in time to PACU recovery.

In clinical practice, only small, clinically unimportant differences in PACU recovery time were observed between the volatile anesthetics. Although oversedation was associated with increased PACU recovery time, differences in the rate of oversedation among agents were insufficient to produce meaningful differences in overall PACU recovery time across the 3 volatile agents. Practical attempts to decrease PACU recovery time should address factors other than volatile agent selection.