The Effect of Lipemia upon Tissue Oxygen Tension in Man

Abstract

SUBSEQUENT to the observation that the intravenous infusion of fat emulsion caused a decrease in the nmyocardial oxygentension of dogs having anl experimentally produced nmyocardial infaretion, it was shown that the hyperlipemia following a large fat meal may precipitate an attack of angina pectoris in patients with severe coronary artery disease. 1-3 These attacks of angina developed about 5 hours after the fat meal, when lipeinia was near its peak. Although sublingual nitroglycerin gave subjective relief, the lipemia-induced angina could also be relieved by the intravenous injection of heparin. The plasma turbidity and triglyeeride level decreased followillg heparin, as expected, due to lipoprotein lipase activity.48 Therefore, it appeared that the level of lipemia had an effect upon the myocardium, i.e., anginal attacks developed at the time of hyperlipemia and were relieved by heparin, which induced "clearingo" of plasma. Since increasing the blood fat level in the dog decreased myoeardial oxygen tension, the present study was undertaken in order to determine whether the level of lipemia affects tissue oxygen tenision in man.The polarographic method of oxygen tension determination, which was used in the study of the dog niyocardium during fat infusion, is also a useful tool for investigation of oxygen tensioni in accessible tissue of man. It has been particularly adaptable to detern-iinations of skin oxygen tension, and thus used extensively in the study of peripheral Supported by a grant from the Lycomning County (Pennsylvania) Heart Association and the Heart Association of Southeasterni Pennsylvania.Presented in part at the Scientific Sessions of the American Heart Association, Philadelphia, Pa., October 25, 1959. Circulatzon, Volume XXII, November 1960 vascular disease. The limitations of the polaroraphic method, and the considerable information that has been obtained by its use, have been well summarized by Montgomery.9In preliminary experiments we had attempted to measure oxygen tension of the skin as lipemia developed following a fat meal. As might be expected, valid determinations of oxygen tension over the several hours of inereasing lipemia after fat ingestion were difficult to make. The polarographic method is most accurate when the subjects remain quiet, the electrode position is not disturbed, and the experiment is brief enough so that the slight downward " drift " of readings which always occurs when electrodes are in place for long periods will not hamper interpretation of data. The following procedure was therefore adopted in which oxygen tension determinations were made over reasonably brief periods during which plasma turbidity either remained at a constant level or decreased after heparin administration.

Pulmonary Vascular Effects of Fat Emulsion Infusion in Unanesthetized Sheep

“…The increased filtration appeared to be solely a result of increased pressure in exchanging vessels because lymph protein concentration de- (25) or to a diffusion defect caused by hyperlipemia (26), then heparin-induced lipolysis should prevent those changes (5,26). In the studies where we gave heparin in doses sufficient to clear the serum of triglycerides, sheep responded to fat emulsion the same way as when no heparin was given.…”

State-of the-Art Review : Endogenous Heparin Activity Deficiency and Atherosclerosis

“…This tension slowly rose to control levels as the serum lipemia cleared and quickly became normal following a small dose of intravenous heparin that lowered the elevated serum triglycerides. Heparin had no such effect on skin oxygen tension in the fasting state (114). High-fat feedings lowered the oxygen supply to hamster brain tissue in one study (115).…”

The Theoretical Background of the Intravenous Nutrition with Fat Emulsions

“…A dim inished oxygen tension in m yocardium and peripheral tissues has been dem onstrated in hyperlipaem ia after fa t infusion (40,72,74). H eparin injection, which dim inishes the lipaem ia, tends to nor m alize the oxygen tension (25,40).…”

“…H eparin injection, which dim inishes the lipaem ia, tends to nor m alize the oxygen tension (25,40). The described im pairm ent of oxygen tran sp o rt is considered in p a rt to depend on aggregation of th e red blood cells (96).…”