Anesth Analg 2004;98:240-241
© 2004 International Anesthesia Research Society
OBSTETRIC ANESTHESIA
Risperidone and Exaggerated Hypotension During a Spinal Anesthetic
James H. Williams, MD, PhD, and
David L. Hepner, MD
From the Department of Anesthesia and Critical Care, Massachusetts General Hospital, Harvard Medical School, and the Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
Address correspondence to: David L. Hepner, MD, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115. Address email to dhepner{at}partners.org
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Abstract
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Antipsychotic medications are often continued through pregnancy and may have important anesthetic interactions. For example, risperidone is an antipsychotic medication with therapeutic effects mediated by dopaminergic and serotonergic antagonism. However, it also possesses potent  -1 adrenergic antagonism. Here we report a case of a parturient with bipolar disease, controlled with lithium and risperidone, undergoing a spinal anesthetic for a cesarean delivery. The parturient developed exaggerated hypotension, refractory to conventional treatment with ephedrine and IV fluids, that eventually responded to large doses of phenylephrine. Risperidone -antagonism should be a consideration for any patient receiving this medication during neuraxial anesthesia. Treatment of significant and refractory hypotension with an -1 agonist such as phenylephrine may be warranted.
IMPLICATIONS: Parturients receiving neuraxial blocks may be taking antipsychotic medications. Although the therapeutic effects of antipsychotic medications are mediated by dopaminergic and serotonergic antagonism, many possess alpha-adrenergic antagonist properties. We report a case of exaggerated hypotension during a spinal anesthetic for cesarean delivery that may have been a result of the alpha-adrenergic antagonism of risperidone.
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Introduction
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Anesthetic interactions with psychiatric medications may be difficult to predict, as new medications are constantly being introduced. Risperidone (Risperdal®) is a relatively new antipsychotic medication that has gained popularity in part because of a decreased incidence of adverse reactions such as extrapyramidal symptoms (1–3). The therapeutic effects of risperidone are mediated by dopaminergic and serotonergic antagonism; however, it also possesses a potent -1 adrenergic antagonism (3,4). We report a case of exaggerated hypotension during a spinal anesthetic that may have been complicated by risperidone -antagonism.
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Case Report
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A 32-yr-old G3P2 female at 39 wk gestation was scheduled for elective repeat cesarean delivery. She was 163 cm, weighed 73 kg and had no allergies. Medications included risperidone 2 mg qhs and lithium 600 mg bid. The lithium level on the morning of surgery was 0.42 meq/L (therapeutic 0.5–1.3 meq/L). Her previous obstetric history included an uncomplicated vaginal delivery with epidural anesthesia at age 21 and a cesarean delivery with a spinal anesthetic at age 28. In the interim between the first and second pregnancy, the patient was diagnosed with bipolar disorder. Medications at the time of the initial cesarean delivery included lithium 600 mg bid and 900 mg qhs, perphenazine 4 mg qhs, benztropine 0.5 mg tid, haloperidol 10 mg tid, and compazine 5 mg tid. The epidural anesthetic was uneventful, and the spinal anesthetic was accompanied by hypotension to 80s/50s that rapidly normalized with ephedrine 20 mg and phenylephrine 40 µg.
For the elective repeat cesarean delivery, a spinal anesthetic was administered at L3-4. The contents of the spinal anesthetic were identical for both cesarean deliveries; it included hyperbaric 0.75% bupivacaine 12 mg, fentanyl 10 µg, and preservative-free morphine 0.2 mg. After uneventful spinal placement without preoperative fluid bolus, the patient was placed supine with left uterine displacement (LUD). Two minutes later, there was a profound decrease in blood pressure from baseline 120/50 to 70/30 mm Hg that was difficult to treat. Initial interventions included 50 mg of ephedrine, extreme LUD and right UD, and 2 L of Ringer’s lactate (LR) solution over the ensuing 3 min. Although the heart rate increased from baseline  80 to 130 bpm, there was little improvement in the exaggerated hypotension with the initial interventions. However, vital signs gradually improved with administration of 600 µg of phenylephrine over the ensuing 10 min. The patient had no overt symptoms such as lightheadedness or nausea during the episode. As this was an elective delivery, no fetal heart rate monitoring was in place, and during the episode attention was focused on preparing for surgery. A healthy baby was delivered with Apgar scores of 61 and 95 39 min after spinal placement. No fetal cord blood gases were obtained. The remainder of the procedure and postoperative course were uneventful. A total of 3400 mL LR was administered, and the blood loss was 700 mL.
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Discussion
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Risperidone has potent -adrenergic antagonism (-1 > -2) that may have made treatment of hypotension difficult in this case (4). Orthostatic hypotension with antipsychotic medications is thought to correlate with -adrenergic antagonism (1,2). Other antipsychotic medications associated with orthostatic hypotension include chlorpromazine, thioridazine, and clozapine (5); however, this adverse reaction can occur with any traditional or atypical antipsychotic medication (2). In practice, cardiovascular side effects of these medications tend to be self-limited and can be overcome with graded increases in dose (2,3). In overdose, risperidone can cause hypotension that, at least in one case, required inotropic support (6).
Specific findings in this case that are consistent with our hypothesis include the large doses of vasoactive medications required for treatment, the resultant tachycardia, and comparison of intraoperative hemodynamics. The tachycardia without improvement in blood pressure coincident with ephedrine administration may have been attributable to the ß-adrenergic effects of ephedrine combined with -adrenergic antagonism of risperidone. In fact, paradoxical hypotension as a result of ß-adrenergic effects has been reported with administration of sympathomimetic and antipsychotic medications in combination (7). In addition, comparison of the initial and subsequent spinal anesthetics for cesarean delivery is consistent with a role for risperidone in contributing to exaggerated hypotension. In each case, identical medications and dosages were included in the spinal anesthetic, and the patient was receiving lithium therapy. However, for the elective repeat cesarean delivery risperidone had replaced other antipsychotic medications, and the intraoperative hypotension was more dramatic.
Anesthetic interactions can be even more difficult to predict when patients take multiple psychiatric medications. Several studies have reported no increase in adverse cardiovascular reactions with lithium in combination with risperidone (8). Although profound hypotension has been reported with lithium toxicity (9), other studies have suggested that serious cardiotoxic effects of lithium only accompany cases of extreme neurologic dysfunction (10). Of note, the patient’s lithium level was subtherapeutic the morning of the surgery.
No previous anesthetic interactions with risperidone have been reported. However, a series has been published describing profound hypotension, and even death, with regional anesthesia in patients treated with the classic antipsychotic medication chlorpromazine (11). This series differs from our case report in that chlorpromazine was administered short term as an antiemetic, sedative, or analgesic adjunct instead of as chronic treatment for psychiatric disease. However, the resultant exaggerated hypotension was very similar to our case. The case series (11) and other reports (7) have suggested using phenylephrine to treat hypotension that may have been attributable to the -adrenergic antagonism of antipsychotic medications. Phenylephrine was most effective in our case, and it may be indicated for treating exaggerated hypotension in patients receiving antipsychotic medications. As -antagonism is not unique to risperidone, this anesthetic interaction is a consideration for any patient receiving antipsychotic medications during neuraxial anesthesia or when hemodynamic instability might be expected.
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Acknowledgments
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Supported, in part, by the Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, and the Department of Anesthesia and Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
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References
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Accepted for publication August 19, 2003.
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Abstract
Introduction
