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A 35-year-old woman receives aprepitant, midazolam, and transdermal scopolamine preoperatively and undergoes an uneventful general anesthetic for an ambulatory procedure with sevoflurane, propofol, fentanyl, and ondansetron. In the postanesthesia care unit, she is slow to awaken and is then agitated and confused. Administration of which of the following medications is MOST likely to improve her symptoms?
A. Naloxone X
B. Physostigmine ✔
C. Cyproheptadine X
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Postoperative delirium is a term used to describe unanticipated changes in cognitive function postoperatively. It is characterized by acute and fluctuating impairment in consciousness, attention, memory, and perception. Postoperative delirium can also be characterized as hypoactive or hyperactive based on the degree of somnolence or agitation. It has been reported that up to 50% of hospitalized surgical patients are affected by delirium, which is associated with an increased risk of morbidity and mortality.
The differential diagnosis for postoperative delirium includes infection, electrolyte abnormalities, psychiatric disorders, adverse effects of perioperatively administered drugs, postictal states, and toxicities. Preoperative risk factors for postoperative delirium include an age greater than 65 years, preexisting cognitive impairment, preexisting morbidity or severe illness, depression, and hearing or vision impairment. Intraoperative risk factors include high-risk, prolonged, or emergency surgery. Postoperative risk factors include prolonged stays in the intensive care unit, poor pain control, and administration of sedatives or opioids.
The patient presented in the clinical scenario received several medications that can contribute to postoperative delirium, with scopolamine being especially culpable. Anticholinergic medications such as scopolamine are frequently administered as treatment or prophylaxis for perioperative nausea and vomiting. Scopolamine can produce several adverse effects, including dry mouth, blurred vision, sedation, and delirium. Physostigmine is an anticholinesterase that readily crosses into the central nervous system and can ameliorate the adverse anticholinergic effects of drugs like scopolamine and atropine. Other anticholinesterases such as neostigmine and pyridostigmine do not cross into the central nervous system and would not be effective in this scenario.
Naloxone would be an appropriate treatment if the patient exhibited evidence of excessive opiate administration such as hypoventilation, somnolence, or hypercarbia.
While serotonin syndrome can present similarly to postoperative delirium and is frequently treated with cyproheptadine, that is not the most likely diagnosis in this scenario.
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Date of last update: March 18, 2025
