Quality of sleep and pulmonary function in clinically stable adolescents with sickle cell anemia.

OBJECTIVE To evaluate quality of sleep and pulmonary function in clinically stable adolescents with sickle cell anemia (SCA). METHODS A cross-sectional descriptive study involving 50 patients with SCA submitted to nocturnal polysomnography and spirometry at the Brasília University Hospital. Anthropometric, polysomnographic and pulmonary function data were analyzed. Patients were divided into two groups according to oxygen saturation by pulse oximetry (SpO2) during rapid eye movement (REM) sleep: SpO2 < 93%; and SpO2 > 93%. Descriptive statistics, Student's t-test, chi-square test and Pearson's correlation coefficient were used. RESULTS Mean age was 13.9 +/- 2.5 years. Total sleep time and REM sleep percentage were lower, whereas REM sleep latency, the number of awakenings, movement during sleep, changes in sleep stage, sleep-disordered breathing index and obstructive apnea index were higher. Two patients (4%) did not present REM. There were statistically significant differences between the groups in most of the polysomnographic variables. The SpO2 in REM sleep presented a strong positive correlation with waking SpO2 and with SpO2 in non-REM sleep, whereas it presented a strong negative correlation with the percentage of total sleep time during which SPO2 was < 90%. Mean spirometric values were within normal ranges. Residual volume and the residual volume/total lung capacity/functional residual capacity ratio were elevated. CONCLUSION Sleep impairment in clinically stable patients with SCA is probably due to hemoglobin desaturation and not to individual alterations in pulmonary function.