Cardiopulmonary arrest following intravenous phenytoin loading.

Two patients, aged 44 and 68 years, presented with generalized seizures either witnessed or highly suspected. Both patients had laboratory-proven subtherapeutic anticonvulsant serum levels. The patients differed with regard to risk; one patient had existing cardiopulmonary disease, and the other was free of such risk factors except liver disease. An apparently appropriate dose of intravenous phenytoin was initiated in each case, and the patients were monitored appropriately and given supplemental oxygen. Bradycardia, hypotension, respiratory distress, and, ultimately, cardiopulmonary arrest occurred in both. The criteria proposed by Earnest et al. should be implemented for each seizure case that requires a decision on the urgent need for therapeutic anticonvulsant levels, whether by mechanical infusion, manual intravenous push, or oral loading. The mechanical infusion is the easiest method to standardize and monitor. The manual intravenous push has a greater possibility of inadvertent overdosage during some small time frame, as well as more local symptoms by some reports. Record et al. have recommended oral loading in selected patients. Careful consideration must be made of the choice of environment in which intravenous loading is done (e.g., emergency department, intensive care unit), as dictated by patient parameters, nursing staff levels, and planned disposition. The crucial factors contributing to the deterioration of both patients in the two cases presented were the concentration of phenytoin manually infused and the possibility that their high-risk status made them poor candidates for manual intravenous phenytoin. Dose and a hypersensitivity reaction were doubtful factors in these cases.