Exercise-induced haemoglobin oxygen desaturation in patients with SCD

Patients with sickle cell disease (SCD) may experience severe clinical complications when there is low tissue oxygenation due to the increased risk of the polymerization of haemoglobin S in deoxygenated environment. The predictors of oxygen desaturation after exercise is not clear in patients with SCD. The current study compared lung function and six-minute walk test (6MWT) between SCD patients with oxygen desaturation after exercise and those without oxygen desaturation.

A cross-sectional study was conducted among adults with SCD (with HbSS and HbSC genotypes) at a large tertiary hospital in Accra, Ghana. Lung function and exercise tolerance (using the 6MWT) were performed for all the study subjects (n=119). Venous blood was collected from all the study subjects for determination of some haemolytic markers. Oxygen saturation was assessed before and after the 6MWT for all the study subjects, and individuals who had oxygen desaturation of ≥3% after the 6MWT were considered as having exercise-induced haemoglobin oxygen desaturation (EIHOD). The lung function and 6MWT were compared between these two groups. Predictors of EIHOD were determined in both HbSC and HbSS patients.

The prevalence of EIHOD in the HbSS and HbSC adults were 41% and 36.1% respectively. Haemoglobin, aspartate amino transaminase, indirect bilirubin, lactate dehydrogenase and six-minute walk distance did not differ in both HbSS and HbSC patients. Decreasing haemoglobin is a predictor of EIHOD in HbSC adults but not HbSS patients. Lung function abnormalities did not predict EIHOD in both HbSS and HbSC patients.

The study demonstrates that SCD patients with EIHOD have similar degree of haemolysis and lung function when compared to those without EIHOD.