Implications of an Abnormal Aminopyrine Breath Test

uses a sampling frame for normal subjects, the AT may be obscured by failure to have adequate measurements over the lower work range; however, anaerobic threshold can be detected in most patients with COPD if proper sampling is employed. The rapid increase in serum lactate level at low work rates might be a function of increased lactate production or a decreased ability to clear lactate during exercise. Increased lactate production secondary to decreased capacity to deliver oxygen to the exercising muscle might result from development ofexercise hypoxemia or increased pulmonary vascular resistance leading to cardiac output limitation. The decreased ability to clear lactate may be a result of deconditioning inherent to COPD. Also, decreased lactate clearance during exercise could result from decreased splanchnic blood flow to the liver’ or possibly passive congestion of the liver secondary to cor pulmonale. The liver is believed to play a significant role in lactate removal.67 It has been demonstrated that in patients with significant hepatic dysfunction, the rise in the serum lactate level during exercise is similar to normal subjects; however, lactate clearance following exercise is impaired.””'