THE OXYHEMOGLOBIN DISSOCIATION CURVE IN ANEMIA

Abstract

A study was undertaken of the affinity of hemoglobin for O2 in 23 anemic patients with normal type A (adult) hemoglobin. On teleologic grounds, a reduction in the affinity of hemoglobin for O2 can be postulated as a desirable compensatory mechanism to permit greater extraction of O2 by the tissues from the blood. Because of the peculiar shape of the oxyhemoglobin dissociation curve (a flat upper portion and a steeply descending mid-portion) a shift to the right of the curve would result in little loss of O2 combining power in the lungs. The in vivo oxyhemoglobin dissociation curve of each patient was outlined by determining the oxygen tension (bubble equilibration techinque), O2 saturation and pH of blood while the patient breathed different concentrations of O2. A reduction in the affinity of hemoglobin for O2 in the form of a rightward displacement of the dissociation curve was demonstrated in patients with hemoglobin levels below 9 g/100 ml. The displacement was moderate in patients with hemoglobin levels between 6.5 and 9.0 g/100 ml, and more marked in those with less than 6.5g/100 ml. The dissociation curve had shifted back toward its normal position in those patients with severe anemia who were restudied after their hemoglobin content had been raised.