Bipolar disorder, also known as manic depression, is a disease associated with shifts in mood and energy. Therapy sometimes includes the use of atypical antipsychotics such as quetiapine (Seroquel®). In the case report “Quetiapine and Refractory Hypotension During General Anesthesia in the Operating Room,” Katherine A. Poole, MS, Department of Anesthesiology and Perioperative Medicine, OHSU, Portland, Oregon, and coauthors describe a 35-year-old normotensive patient who presented for a revision septoplasty. Preoperative medications included lamotrigine, quetiapine, and venlafaxine XR. She had no history of cardiac disease.
Five minutes after standard anesthetic induction doses her blood pressure sank to 49/30. Usual maneuvers for raising her blood pressure were tried, including boluses of ephedrine boluses and phenylephrine, a liter of intravenous fluid, and reduction in the inhaled desflurane from 6% to 5%. This aggressive intervention managed to raise her blood pressure rose to just 80/31, so the authors resorted to 4 unit vasopressin boluses. Over a 2-hour period of time she received 40 mg ephedrine, 1500 μg phenylephrine and 20 units of vasopressin.
The authors presumed the profound hypotension was due to quetiapine. Indeed, clozapine, another atypical antipsychotic, has also been reported to cause refractory hypotension during anesthesia. In the latter report vasopressin also helped restore blood pressure. Vasopressin might not always be thought of as a cure for intraoperative hypotension.
Certainly α1-adrenergic-receptor antagonism is seen with atypical antipsychotics. Vasopressin can promote vasoconstriction through the V1 receptor even with α1-blockade. The dose of vasopressin used in both of these reports is lower than the 40-unit dose recommended during ACLS.
It’s not clear how often patients who receive atypical antipsychotics become hypotensive during anesthesia. With the use of electronic anesthesia records, the incidence might be easy to determine. Though the exact definition of intraoperative hypotension could be debated, few anesthesiologists would consider a BP of 49/30 to be just another routine anesthetic induction.