The Effect of Anesthetic Choice (Sevoflurane Versus Desflurane) and Neuromuscular Management on Speed of Airway Reflex Recovery.

BACKGROUND: Nonintubated patients receiving sevoflurane have slower protective airway reflex recovery after anesthesia compared with patients receiving desflurane. We asked whether this difference would remain significant among intubated patients receiving rocuronium or whether the impact of variable neuromuscular recovery would predominate and thus minimize differences between anesthetics.

METHODS: After obtaining written informed consent, patients were randomly assigned to receive sevoflurane (n = 41) or desflurane (n = 40), with neuromuscular monitoring by quantitative train-of-four (TOF) method using accelerometry. Intubation was facilitated by administration of 1 mg/kg rocuronium. Neuromuscular block was produced, with the goal of maintaining 10% to 15% of baseline function. After surgery, neostigmine 70 µg/kg + glycopyrrolate 14 µg/kg was administered. When TOF ratio reached ≥ 0.7, anesthetic was discontinued and fresh gas flow was raised to 15 L/m. The time of first response to command was noted, after which patients were given a 20-mL water swallowing test at 2, 6, 14, 22, 30, and 60 minutes. The following average time intervals were compared between the 2 intervention groups: anesthetic discontinuation to first response to command (T1); first response to command to first successful passing of swallow test (T2); and anesthetic discontinuation to first successful passing of swallow test (T3). We also compared the rates of successful swallow tests at 2 minutes after first response to command in the 2 groups, first categorizing as failures all those who were unable to take the test at 2 minutes, and then excluding 10 patients unable to take the test at this time for reasons other than somnolence (n = 10).

RESULTS: Patients receiving desflurane passed the swallowing test at shorter time intervals after first response to command than did patients receiving sevoflurane (Wilcoxon-Mann-Whitney odds = 1.60; 95% confidence interval [CI], 1.01-2.69; P = 0.054). Two minutes after the first response to command, among all 81 patients, the chance of passing the swallowing test was higher after desflurane compared with sevoflurane anesthesia (relative risk = 1.6; 95% CI, 1.0-2.5; P = 0.04). Of the 71 patients (as above), we observed a significantly higher chance of passing at 2 minutes after first response to command (relative risk = 1.8; 95% CI, 1.2-2.7; P = 0.006) in patients receiving desflurane (25/33) compared with those receiving sevoflurane (16/38). In 18 of 81 and 16 of 71 patients, the neuromuscular monitoring and reversal protocols were not followed (neostigmine underdosed, extubation at TOF <0.7, or reliance on tactile as opposed to quantitative TOF measurement). In both the total cohort and the subset of 71, neuromuscular protocol adherence increased the chance of passing the swallow test, independent of anesthetic assignment in multivariable logistic regression (P = 0.02 and P = 0.006, respectively), demonstrating significant effect on airway reflex recovery independent of chosen anesthetic.

CONCLUSIONS: Compared with sevoflurane, desflurane allowed faster recovery of airway reflexes after anesthesia in intubated patients. Clinical management of neuromuscular block, including full reversal and the use of quantitative TOF, affects airway reflex recovery-an effect that may be at least as profound as the choice of potent inhaled anesthetic.