Synergism between halothane and labetalol

A patient in chronic renal failure, who was receiving large doses of the combined alpha- and beta-blocking agent, labetalol, was selected for renal transplantation. A low concentration of halothane was used for induction and maintenance of anaesthesia, but severe myocardial depression occurred which proved unresponsive to atropine or isoprenaline, although it responded to a dopamine infusion. Synergism has already been reported between labetalol and high concentrations of halothane, but this case suggests that, in patients with previous myocardial damage, much lower concentrations of this inhalational agent may prove fatal.