Impact of Anesthetic Choice (Sevoflurane Versus Desflurane) on Airway Reflex Recovery in the Context of Antagonized Neuromuscular Block

Protective airway reflexes may be impaired in the postoperative period, creating the
potential for aspiration of gastric contents, even after a patient exhibits appropriate
response to command. Because assessment of airway reflex recovery is not possible in an
intubated patient, the clinician must make an empiric decision as to when a patient is safe
to extubate, and choose a combination of techniques least likely to result in pharyngeal
impairment. Adequacy of reversal of neuromuscular block by cholinesterase inhibitors (e.g.,
neostigmine) is unpredictable, especially in the presence of profound paralysis, and tactile
assessment of train-of four and sustained tetanus has shown poor correlation with objective
assessments. Protective airway reflexes may also be impaired during early recovery by the
anesthetics themselves, even when muscle relaxant has been avoided. In the absence of muscle
relaxant the investigators previously demonstrated that patients receiving an anesthetic
with higher tissue solubility, sevoflurane showed significantly greater impairment of
swallowing up to 14 minutes after response to command compared to patients receiving an
anesthetic with lower tissue solubility, desflurane. Therefore, we ask whether the
combination of the more soluble anesthetic and the presence of neuromuscular block
antagonized by neostigmine may create a multiplicative effect that might further prolong
pharyngeal recovery. We plan to randomly assign 100 patients scheduled to undergo surgery
with general anesthesia to a standardized anesthetic that includes 1) sevoflurane,
rocuronium with 70 µg/kg neostigmine + 14 µg/kg glycopyrrolate antagonism (group S); or 2)
desflurane, rocuronium with 70 µg/kg neostigmine + 14 µg/kg glycopyrrolate antagonism (group
D). Airway reflex recovery will be judged as adequate by the patient's ability to swallow 20
mL of water without coughing or drooling 5, 10, 15, 20, 30 and 60 minutes after response to
command. Anesthetic (sevoflurane or desflurane) will be discontinued after administration of
reversal agent and recovery to TOF (train-of-four) ratio of 0.7.