CARDIOPULMONARY PHYSIOLOGICAL RESPONSES TO HEAVY EXERCISE IN PATIENTS WITH ANEMIA *

Abstract

Nine patients with various types of anemia achieved levels of 3 min. treadmill exercise equal to or greater than that which produced maximal O2 intake in 15 normal subjects. At standing rest ventilation, respiratory rate, cardiac output, stroke volume, arterio-venous differences of pCO2, pH and plasma (HCO3) were increased in anemic patients. During exercise; at equal ventilation, cardiac output, venous pO2, stroke volume and arteriovenous pH difference; respiratory rate was nearly double normal. Arterial and venous O2 content, CO2 content, CO2 tension, pH, O2 intake, and CO2 production were decreased below normal. Stroke volume increased from rest to exercise in both groups. Alveolar-arterial O2 gradients in anemic patients averaged 40 mm Hg during standing rest and exercise while in normal subjects the gradients increased from 13 to 22 mm Hg. Despite evidence for increased anerobic metabolism and reduced buffering capacity anemic patients exhibited no greater reduction of plasma (HCO3) or venous pH, and experienced no more symptomatic distress than did normal subjects. An improved mechanical efficiency or lag in release of acid metabolites during brief severe exertion of anemic patients is suggested.