Clinical Considerations

Postoperative recovery: Emergence time and special populations

Emergence time is an important metric of anesthetic performance because rapid postoperative recovery is believed to be associated with decreased time spent in the OR and quicker OR turnover, which has implications for staffing costs and hospital budgets as potential delays for scheduled operations. Several measurements are used to report emergence time, including time to eye opening, time to obey commands, time to extubation, and time to orientation.

It should be noted that although faster emergence times may be associated with improved OR turnover rates, many other factors also contribute to OR turnover and its associated costs, including local workflow practices (e.g. patient transport, cleaning, equipment setup), administrative decisions on case scheduling, and staffing arrangements.¹ After a provider education and anesthetic agent labelling initiative at the University of Wisconsin anesthesia department, they found a reduction in average turnover time (4 min over 3-year period), rather than an increase, as providers increasingly switched to sevoflurane in favour of desflurane.¹

Numerous randomized control trials have investigated the post-operative recovery outcomes of desflurane and sevoflurane. For both ambulatory and in-patient surgeries involving adults or children, the times until patients followed commands, were extubated, and were oriented were significantly faster with desflurane by 1–2 minutes.² Specifically, time to obey commands was quicker by 1.7 minutes (95% CI 0.7–2.7 min), time to extubation was quicker by 1.3 minutes (95% CI 0.4–2.2 min), and time orientation was improved by 1.8 minutes (95% CI 0.7–2.9 min) with desflurane.² Time to eye opening was quicker with desflurane by 3.3 min (95% CI -4.02, -2.61).³ No differences were found to be associated with patient age or duration of anesthesia. Additionally, a third meta-analysis that quantified differences in emergence as relative values found that desflurane reduced the time to extubation by 25% and the time to follow commands by 19% compared to sevoflurane.⁴ In other words, where emergence with sevoflurane was expected to take 4–12 minutes, emergence with desflurane on average was 1–3 minutes faster. Similar results were found for LMA procedures performed in an adult ambulatory population.⁵ In this group, time to remove LMA was 1.4 minutes quicker (95% CI 0.6–2.1 min) and time to obey commands was 2.0 minutes quicker (95% CI 1.4–2.6 min) for desflurane compared to sevoflurane. Time to eye opening was also 3.8 minutes (95% CI 3.0–4.6 min) faster for desflurane. Overall, the literature suggests that desflurane improves emergence times by up to 4 minutes.

Certain patient populations may benefit more from faster emergence times. For example, obese patients are at a greater risk of aspiration, airway obstruction, and hypoxia in the perioperative period.⁷ Two systematic reviews and meta-analyses found that obese patients recovered from anesthesia 3-8 min faster with desflurane compared to sevoflurane.^6,7 Similarly, a systematic review and meta-analysis in children found that desflurane was associated with a 2-3 min shorter extubation and awakening times compared with sevoflurane.⁸ Additionally, a systematic review and meta-analysis in elderly patients (>65yo) found that recovery after desflurane anesthesia was 1-5 min faster compared with sevoflurane.⁹

Safety

Three meta-analyses compared the safety profiles of desflurane and sevoflurane (Table 6). In terms of postoperative nausea and vomiting (PONV), a serious yet common anesthetic complication associated with unanticipated admissions, ^10,11 no differences in occurrence were noted between sevoflurane and desflurane.^2,3 Conversely, the risk of respiratory complications including airway irritation, cough, respiratory distress, and laryngospasm, was elevated for desflurane (20%) compared to sevoflurane (13%).³ This trend was also noted in an earlier meta-analysis by Stevanovic et al., although significance at that point could not be proven.⁵ Thus, in addition to being a more sustainable option, sevoflurane appears to be the safer volatile agent.

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