Relationship between ventilation heterogeneity and exercise intolerance in adults with sickle cell anemia

Abstract Sickle cell anemia (SCA) causes dysfunction of multiple organs, with pulmonary involvement as a major cause of mortality.Recently, there has been growing interest in the nitrogen single-breath washout (N 2 SBW) test, which is able to detect ventilationheterogeneity and small airway disease when the results of other pulmonary function tests (PFTs) are still normal. Thus, theobjectives of the present study were to assess the heterogeneity in the ventilation distribution in adults with SCA and todetermine the association between the ventilation distribution and the clinical, cardiovascular, and radiological findings. Thiscross-sectional study included 38 adults with SCA who underwent PFTs, echocardiography, computed tomography (CT), and6-min walk test. To evaluate the ventilation heterogeneity, the patients were categorized according to the phase III slope of theN 2 SBW (SIII N2 ). Compared with adults with lower SIII N2 values, adults with higher SIII N2 values showed lower hemoglobin levels(P=0.048), a history of acute chest syndrome (P=0.001), an elevated tricuspid regurgitation velocity (P=0.039), predominance ofa reticular pattern in the CT (P=0.002), a shorter 6-min walking distance (6MWD) (P=0.002), and lower peripheral oxygensaturation (SpO