The defect in pulmonary gas transfer in patients with sickle cell disease.

Nine patients with sickle cell disease and without concomitant cardiopulmonary illness or acute problems were studied with lung function tests. Besides arterial hemoglobin unsaturation, found in all cases so studied, a slight decrease in PaO2 was also present. The pulmonary gas transfer defect was studied and found to be due mostly to increased right to left shunting, although uneven ventilation/perfusion relationships seem to have been a factor in a few cases. Our data clearly show that the diffusion was not implicated in the gas transfer defect. The clinical implications of this little studied and less mentioned respiratory defect are discussed. Since the defect may enhance the risk of sickling crises, it should be measured in each individual patient, for appropriate prophylactic measures. After accidents, pre and post-operatively and during acute respiratory illness, the defect should be again reevaluated. In all probability many patients will be discovered who represent a respiratory risk, and may require special immunizations, prophylactic antibiotics, professional relocation and, during emergencies, intensive respiratory care.