Mixed venous oxygen tension and hyperlactatemia. Survival in severe cardiopulmonary disease
P. Kasnitz, G. L. Druger, F. Yorra and D. H. Simmons
Mixed venous oxygen tension (PVo2), cardiac output (Q), and arterial oxygen
tension (Pao2) were measured in 20 patients with severe cardiac or
pulmonary disease or both to determine which of these variables would best
predict hyperlactatemia and survival. There was no correlation between Pao2
and either hyperlactatemia or survival, possibly because all oxygen
tensions were greater than 40 mm Hg. There was a good correlation between Q
and both hyperlactatemia and survival, and a slightly better correlation
between PVo2 and both hyperlactatemia and survival. Mixed venous oxygen
tension, a reflection of both Pao2 and Q, was a better predictor of
hyperlactatemia and death than either arterial Pao2 or Q alone. It is also
more easily measured and, therefore, more clinically useful than either Q,
as a predictor of anaerobiosis and survival, or blood lactate
concentration, as a predictor of survival. A mixed venous oxygen tension
below 28 mm Hg was usually associated with hyperlactatemia and was always
associated with death.
