Circulatory and metabolic changes in the brain during induced hypotension--comparison among trimetaphan, glycerin trinitrate and prostaglandin E1.

Induced hypotension was carried out using trimetaphan (TMP), glycerin trinitrate (GTN) and prostaglandin E(1) (PGE(1)) in 45 patients received elective abdominal surgery under anesthesia with enflurane in N(2)O/O(2) in order to evaluate and compare the effects of these three agents on cerebral circulation and metabolism. Upon reduction of mean arterial blood pressure to 60-65 mmHg, cerebral blood flow decreased in the TMP and GTN groups but increased in the PGE(1) group. The changes were quite proportional to those in cardiac index in the three groups. Cerebral oxygen consumption decreased only in the TMP group. Changes in cerebrospinal fluid pressure were not in parallel with those in cerebral blood flow. The former decreased slightly in the TMP group but increased in the GTN and PGE(1) groups. These results offered a great caution for induction of artificial hypotension using these agents.