Anesthetic considerations for electroconvulsive therapy.
Electrically induced seizures have been used widely to treat psychiatric disease since their introduction in 1938. Seizure activity is the therapeutic aspect of this form of treatment, but it is accompanied by untoward physiologic consequences. Cardiovascular responses consist of generalized autonomic nervous system stimulation with initial parasympathetic outflow, followed immediately by a sympathetic response. In certain patients the sequence described may result in an initial bradycardia or even asystole, followed by tachycardia, dysrhythmia, and hypertension. The cerebrovascular system responds with a marked increase in cerebral blood flow in response to increased cerebral oxygen consumption, and dramatic elevation of intracranial pressure. General anesthesia for electroconvulsive therapy (ECT) must be administered only in locations equipped for support of the unconscious patient and treatment of complications. Intravenous access is mandatory in all patients, as is monitoring of blood pressure, and ECG, as well as pulse oximetry. Appropriate oxygen supplementation and ventilatory support are essential as they are during any procedure necessitating general anesthesia. Methohexital, 0.75 to 1.0 mg/kg intravenously, is the most frequently used agent for induction of anesthesia for ECT; muscle relaxation usually is accomplished with succinylcholine, 0.5 to 1.0 mg/kg. In patients at risk for ill effects from the tachycardia and hypertension that may accompany sympathetic nervous system response to ECT, nitroglycerin, propranolol, hydralazine, or other sympatholytic agents should be used to attenuate the potentially harmful sequelae of ECT. The efficacy of ECT requires a knowledge of anesthetic precepts, an understanding of the interaction between anesthetic drugs and seizure activity, and an awareness of the physiologic effects of ECT as well as the treatment of those effects.