Effect of Polycythemia on Respiration

¹ From the Laboratory of Thoracic Physiology, Division of Anesthesiology, and the Department of Physiology, Washington University School of Medicine, St. Louis, Missouri

Polycythemia was achieved by transfusion of a young adult male. Studies were made before transfusion, during polycythemia and after return to a normal blood level. Minute volume of respiration and oxygen consumption were measured at varying work levels on a bicycle ergometer while breathing 14% oxygen, air and 100% oxygen. An increase in hematocrit from 40 to 60% resulted in a consistent depression of ventilation during exercise. This was more pronounced during breathing of 14% oxygen than of room air; during breathing of pure oxygen little change in ventilation occurred. The classical concepts of carotid and aortic chemoreceptor activation are not adequate to explain this ventilatory effect of polycythemia. Decrease in blood flow through these structures, and central pH as a factor modifying their effectiveness as a stimulant to respiration, might yet implicate them.