The effect of thiopentone on enflurane-induced cortical seizures

The effect of thiopentone 0.5 and 1.0 mg/kg on the enflurane-induced cortical spike discharge has been examined. Seven cats were anaesthetized with enflurane in oxygen and ventilation was controlled to maintain eucapnia during e.e.g. recording. End-tidal enflurane concentrations of between 1.2 and 2.2% provoked dose-dependent spontaneous spike discharges reproducibly. It was found that, during light enflurane anaesthesia, intravenous thiopentone could exacerbate e.e.g. signs of seizure activity. However, at a greater depth of anaesthesia spike activity was suppressed. The e.e.g. changes following thiopentone resembled the effects of still greater concentrations of enflurane.