Effect of exercise on arterial lactate, pyruvate and excess lactate in chronic bronchitis

Arterial blood lactate and pyruvate were estimated at rest and during exercise in 14 patients with chronic bronchitis. Resting arterial lactate, pyruvate and lactate:pyruvate ratios were within the ranges previously reported in normal subjects. Lactate values increased significantly during mild exercise. Lactate:pyruvate ratios also increased and calculated excess lactate (XL) was present in seven patients. Cardiac output increased in most patients during mild exercise. Changes in arterial oxygen saturation (Sao₂) were small and not significant. There was no correlation between increases in arterial lactate values and changes in Sao₂. The lactate and pyruvate levels at rest confirm previous observations, and provide no evidence for the existence of cellular hypoxia in patients with chronic lung disease. The changes during mild exercise in patients with chronic bronchitis not in failure were similar to those reported in normal subjects, and indicate that tissue hypoxia of similar degree develops in both groups.