To identify the influence of hydroxyurea (HU) on oxygen saturation levels among patients with Sickle Cell Disease (SCD).

A cross-sectional study was carried out that evaluated the use of HU for at least 1 year and the oxygen saturation measured on the oximeter in patients recruited in a SCD cohort in Brazil.

A total of 275 patients were evaluated and 132 were included in this study. Inclusion criteria were (i) SS genotype, (ii) age over 18 years, (iii) HU use for more than 1 year (iv) no HU use, (v) active follow-up. Patients who did not use HU were the control group. The HU group had 57 patients with a mean age of 32 (±13.38) years, 50.88% women and 49.12% men. The means of Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP), Heart Rate (HR) and Oxygen Saturation (SpO2) in this group were, respectively, 117.95 (±15.52) mmHg, 65.39 (±11.22) mmHg, 81.40 (±14.55) bpm and 93.02 (±14.55)%. The Control group consisted of 32 patients, the mean age was 30.50 (±10.92) years, 56.25% were women and 43.75% were men. The means of SBP, DBP, HR and SpO2 in the control were respectively 114.69 (±12.37) mmHg, 62.44 (±9.37) mmHg, 80.19 (±15.66) bpm and 90.16 (±6.16)%. The difference between SpO2 in the groups was statistically significant (p = 0.01). In the other variables evaluated there was no statistical significance.

Oxygen desaturation is common in SCD and predicts clinical severity. Hypoxemia is associated with risk of stroke, abnormal transcranial Doppler velocities, elevation of tricuspid regurgitation, diastolic dysfunction, increased incidence of vaso-occlusive crises and chest syndrome sharp. Pulse oximetry is a non-invasive method of measuring oxyhemoglobin saturation. Peripheral perfusion, external light sources, and skin color and device quality should be observed. HU is the primary therapy in SCD and is capable of increasing the production of fetal hemoglobin (HbF). Studies have shown a strong correlation between peripheral SpO2 and HbF level, so treatments that elevate HbF should impact desaturation and be beneficial for complications associated with hypoxia. In the United Kingdom, there is already a recommendation from the HU for the treatment of chronic hypoxemia in SCD.

The measurement of SpO2 is crucial for effective management in SCD. The association between HbF and SpO2 reaffirms the importance of interventions that are able to increase both, like the HU. This study shows that the patients under use of HU had a significantly higher SpO2 when compared to patients without it.