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Severe hypotension following spinal anesthesia in a patient treated with risperidone

Hospital Universitari Doctor Josep Trueta, Catalonia, Spain, E-mail: anesthesia{at}htrueta.scs.es

To the Editor:

We describe a case of profound hypotension during spinal anesthesia in a patient treated with risperidone that was partially refractory to conventional treatment with large doses of ephedrine and iv fluids.

A 69-yr-old woman was scheduled for repair of hip fracture. She was 161 cm, weighed 72 kg and had no allergies. Her medical history included diabetes mellitus and vascular dementia. Medications included insulin and risperidone 2 mg. The patient was given 1 mg etomidate and was placed in the sitting position. Spinal anesthesia was achieved successfully on the first attempt at L3–L4, using a 25-gauge spinal needle. Thirteen milligrams of 0.5% hyperbaric bupivacaine were administered leading to a T9 block. Ten minutes later, there was a profound decrease in blood pressure from baseline 142/90 to 72/43 mmHg. Oxygen saturation remained at 98%. Initial interventions included 1000 mL of Ringer’s lactate solution and 50 mg of ephedrine iv in of 5 mg increments over the ensuing 20 min. There was only a minor improvement of blood pressure to 82/51 mmHg, without a heart rate increase. Other interventions included 500 mL of 6% hetastarch and 50 mg of ephedrine iv in of 10 mg increments over the ensuing 20 min and vital signs gradually improved to baseline. The patient had no overt symptoms such as lightheadedness or nausea during the episode.

Risperidone is an atypical antipsychotic medication with both 5-HT₂ receptor and D₂ dopamine receptor antagonism, but also possesses affinity for both ₁ and ₂-adrenoceptors and can cause hypotension. It is used for the treatment of behavioural and psychological symptoms in patients with dementia because it reduces delusions, aggression and agitation without severe extrapyramidal symptoms. Orthostatic hypotension and tachycardia due to anticholinergic or ₁-adrenoreceptor blockade may occur in the majority of patients at therapeutic dosages of antipsychotic drugs.¹ Depletion of presynaptic norepinephrine stores and -adrenergic antagonism by antipsychotic medication should be considered when profound hypotension occurs during spinal anesthesia. Only one prior case has been published describing profound hypotension in a parturient with bipolar disease, controlled with lithium and risperidone, undergoing spinal anesthesia for Cesarean delivery. The patient was refractory to conventional treatment with ephedrine and iv fluids, and eventually responded to large doses of phenylephrine.² The treatment should consist of iv fluids and sympathomimetic drugs. Epinephrine and dopamine are not recommended, as ß-stimulation may worsen hypotension due to risperidone-induced -adrenergic antagonism.

References

1 Buckley NA, Sanders P. Cardiovascular adverse effects of antipsychotic drugs. Drug Saf 2000; 23: 215–28.[Medline]

2 Williams JH, Hepner DL. Risperidone and exaggerated hypotension during a spinal anesthetic. Anesth Analg 2004; 98: 240–1.[Abstract/Free Full Text]

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