Metabolic Effects of Anesthesia

Abstract

17 dogs were anesthetized with ether after a total epidural preganglionic sympathetic block had been established and maintained with 0.45% procaine HC1 injd. into the epidural space. 12 dogs with total sympathetic block and arterial ether levels of 90 mg.% failed to show any alteration of lactic acid, pyruvic acid, lactic acid/pyruvic acid ratio, total fixed acids or blood sugar during the anesthesia. Five dogs with total sympathetic block, with arterial ether levels of 100-180 mg.%, showed no change in blood sugar or pyruvic acid but consistent rises in lactic acid, total fixed acids and lactic acid/ pyruvic acid ratio during ether anesthesia. These changes were small in magnitude in comparison to those seen in the unblocked dog and most probably represent tissue anoxia secondary to a critical reduction in cardiac output and peripheral blood flow in the dog with a sympathetic block at deep levels of ether anesthesia. The fall in serum K during ether anesthesia in the normal dog reported by Fay and observed by the authors is of the same order of magnitude as occurs following the injn. of epinephrine and does not occur during ether anesthesia in the dog with a total sympathetic block. Alterations in serum K concns. in the normal dog during ether anesthesia are regarded as being directly due to an epinephrine effect. A total epidural preganglionic sympathetic block prevents the reflex sympatho-adrenal output of epinephrine and norepinephrine in the dog during ether anesthesia. By this method the metabolic effects of epinephrine liberated during ether anesthesia were eliminated and the direct effects of diethyl ether on cellular metabolism were studied. Johnson''s observation was confirmed that hyperglycemia does not occur during ether anesthesia in the dog with a total sympathetic block. Ether fails to produce a metabolic acidosis in the dog with a total sympathetic block at levels of ether anesthesia that do not produce a critical reduction in cardiac output and peripheral blood flow. From the data presented it is concluded that the metabolic acidosis and hyperglycemia found in dogs during ether anesthesia are directly related to the quantitative output of epinephrine with the resultant mobilization by epinephrine of liver glycogen as glucose and of muscle glycogen as blood lactic acid.