A Simple Method for Prolonging Therapeutic Insulin Coma. ∗

In the treatment of psychoses, insulin coma 1 (or the period of unconsciousness) is generally not allowed to persist beyond an hour or an hour and a half. In cases inadvertently allowed to linger in coma beyond that period, an irreversible insulin coma 2 frequently follows that can no longer be relieved by intravenous glucose. This dangerous and sometimes fatal complication has, however, directed the attention of several investigators to the important fact that patients who survive several hours or days of this relatively irreversible coma often show dramatic psychiatric improvement on awakening. Kraulis 3 attempted to utilize this phenomenon for therapeutic ends by prolonging insulin coma with periodic small glucose feedings sufficient to sustain the patient but not sufficient to rouse him. The difficulties in the clinical management of these sporadic feedings, however, and the frequent presence of gastric retention 2 (which Kraulis did not suspect) made this mode of treatment too dangerous for clinical application.

It can be assumed that the cerebral injury which ensues in accidentally protracted coma is due to the diminution of brain metabolism (by withdrawal of substrate) below levels adequate for cell maintenance over long periods of time. In our cases (30 experiments on 10 subjects), we have succeeded in prolonging hypoglycemia as long as 21 hours and coma as long as 18 hours, without mishap, by sustaining brain metabolism above this dangerous level, but still below levels which support consciousness and other associated cerebral functions. This has been achieved by administering infusions of 5 % glucose in physiological saline (Sterisol) intravenously at controlled rates. Inasmuch as large doses of insulin exert their hypoglycemic effect for many hours after administration, 4 one need only maintain the blood glucose at a moderately high level (e.g., 35 mg per 100 ml) to prolong coma for many hours. When the insulin effect begins to subside, a fresh intraiiiuscular iiljection of insulin can be administered.