THE EFFECT OF HEXAMETHONIUM AS COMPARED TO PROCAINE OR METYCAINE LUMBAR BLOCK ON THE BLOOD FLOW TO THE FOOT OF NORMAL SUBJECTS 12

Abstract

As an evaluation of the suggestive clinical and skin temp, evidence that the autonomic ganglionic blocking agent hexamethylene-bis-trimethylammonium bromide (hexamethonium or C6) caused a greater increase in foot blood flow than any previously known agent, a water-filled foot plethysmograph of the type described by Abramson (1944) was used to measure quantitatively the increment to foot blood flow following (1) intraven. admn. of 50 to 100 mg. of C6 ion and the presumably complete blocking of the lumbar sympathetic outflow with metycaine 1% injected into the epidural space or procaine 1% intrathecally. These procedures were carried out on alternate days on 10 healthy young medical students in a constant temp, cold room. Simultaneously, skin temps, were recorded continuously with iron-constantin thermocouples, and toe pulse volume and blood flows were recorded with a Burch-Winsor digital plethysmograph. Five of the subjects showed greater increment of blood flow to the foot following C6, while the flow following regional block was greater in the other 5. The avg. maximum foot blood flow for all 10 subjects following C6 was 9.8 cc/100 cc. of foot per min., while following regional block it was 10.2 cc/100 cc. per min., a difference not statistically significant. Skin temp, rise paralleled foot blood flow rise as measured plethysmographically, but in a qualitative fashion only. Digital blood flow changes paralleled closely foot blood flow changes, but digital pulse volume increase was consistently greater following regional block than following C6. Reflex sympathetic vasoconstriction in the toes to "noxious" stimuli was blocked in every instance following both regional block and C6. These data suggest that the blood flow following block of sympathetic vasoconstrictor impulses to the vessels of the foot after intraven. admn. of C6 in normal humans may approach that achieved by the presumably complete block with regional anesthesia.