Date of Award

4-1970

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Medical

First Advisor

Lyle Hamilton

Second Advisor

G.B. Spurr

Third Advisor

William J. Stekiel

Abstract

During the period from Mid 1968, Dr. Larry C. Carey, while commanding a shock unit for the United States Navy in South Viet Nam, made the observation that some patients who were apparently resuscitated adequately from profound shock had persistantly [sic] elevated blood lactate levels. Many of these patients had a concurrent hypoxemia due to congestive atelectasis and other pulmonary problems. The question arose ... did the elevated lactate reflect an inadequate arterial oxygen tension, an inadequate perfusion or a combination of both? Many of these patients had normal blood pressure, pulse rate and cardiac output, but it was possible that circulation was still not adequate to supply the peripheral tissues with sufficient oxygen. Peripheral arterovenous shunting or an oxygen debt could have been demanding a greater peripheral flow of oxygen than was being supplied.

The interrelation between blood flow, blood O2 tension and anaerobic metabolism is a complex one; but some insight into that relation might be possible if one knew how far arterial oxygen tens ion must be lowered before lactic acid accumulates. Blood flow must be held constant or controlled in some way in order to obtain valid results.

An experiment was designed in which dogs were subjected to acute progressive hypoxemia while cardiac output and excess lactate were monitored. If excess lactate accumulated before cardiac output falls, then it might be possible to get at least a preliminary insight into the importance o! arterial oxygen tension as an isolated determinant of lactate production and anaerobic metabolism. Although such a study would not be able provide precise information for situations of hypoxemia and hypoperfusion, it might provide some useful impressions concerning the relative importance of arterial oxygen tension and tissue perfusion.

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