The antiarrhythmic effect of esmolol, a selective beta 1 adrenoreceptor blocker, was evaluated in the presence of epinephrine induced arrhythmias in dogs (n = 6). The arrhythmogenic dose of epinephrine (ADE) during 1.2 MAC halothane in dogs was increased from 3.23 +/- 0.25 (mean +/- SD) to 30.90 +/- 3.56 micrograms.kg-1.min-1 (P less than 0.001) by the prior administration of esmolol 0.5 microgram.kg-1 bolus followed by an infusion at the rate of 150 micrograms.kg-1.min-1. Higher esmolol infusion doses of 200 micrograms.kg-1.min-1 further increased ADE to 99.0 +/- 2.92 micrograms.kg-1.min-1 (P less than 0.001). After discontinuation of esmolol and during continued halothane anaesthesia, ventricular tachycardia was induced by increasing the infusion rate of the 100 micrograms.ml-1 solution of epinephrine. In all dogs ventricular tachycardia was restored to sinus rhythm by a bolus dose of esmolol (1 microgram.kg-1). We conclude that esmolol pretreatment increases the ADE during halothane anaesthesia in dogs. Our data suggest that esmolol may be useful as an antiarrhythmic agent in the management of epinephrine-related ventricular arrhythmias during anaesthesia in man.

A five-year retrospective study investigating the effects of psychotropic medication on first seizure length was undertaken on 109 patients who received 131 courses of electroconvulsive therapy (ECT). Bilateral ECT was administered under methohexitone anaesthesia. Induction of a seizure was successful in 105 patients. Stepwise linear regression analysis showed that except for selective serotonin reuptake inhibitors (SSRIs) seizure length was not affected by psychotropic medication, SSRIs were associated with prolonged seizure length (p=0.0012). Less than one-third of the subjects had drugs with anticonvulsant properties omitted before treatment. Drugs with anticonvulsant properties did not shorten seizure length. Though this study suggests that SSRIs may prolong fit length, further clarification of the predictors for seizure duration is required.

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