Changes in serum potassium and blood glucose concentrations after trimethaphan administration in man

Blood glucose and serum potassium (K+) concentrations were measured before, during, and 60 minutes after operation in two groups of 10 patients during nitrous oxide/halothane/d-tubocurarine anesthesia for major orthopedic surgery. In the control group, arterial blood pressure was maintained within normal range, while in the study group trimethaphan camsylate was administered as an intravenous infusion (average, 218 mg.) to maintain a systolic blood pressure of 60 to 65 torr. In the normotensive group, blood glucose rose significantly during operation and early postoperatively and serum K+ was essentially unchanged. In the hypotensive group, trimethaphan caused a striking modification of surgically induced hyperglycemia, together with a small significant decrease in serum K+ intraoperatively. The observed increase in blood glucose is part of the autonomic response to surgical stress. Hormonal factors (growth hormone, cortisol and glucagon) may conceivably be involved. The decrease in serum K+ is probably caused by decreased hepatic glycogenolysis and attenuation of the suppressive effect of catecholamines on insulin release, both effects being secondary to the ganglionic blocking property of trimethaphan. These results indicate that trimethaphan, in contrast to other ganglionic blocking drugs, does not cause hypoglycemia and suggest that serum K+ concentration should be monitored whenever these drugs are used.