Blood-oxygen affinity and sickling in sickle cell disease: effect of prior deoxygenation

The influence of prior deoxygenation on whole blood-oxygen affinity was determined in samples from persons with sickle cell anemia (SS blood) and compared to blood from normal and anemic subjects (AA blood). The oxygen affinity of SS blood (measured as P50) is significantly decreased when this blood is exposed for 30 min to nitrogen before the determination of the oxygen equilibrium curve. The decrease is directly related to the number of sickle cells that are present in the samples. The present work emphasizes the importance of experimental conditions on the results of the determination of SS blood-oxygen affinity and the difficulties inherent in the evaluation of in vivo oxygen transport in sickle cell disease.