Prevalence and factors associated with nocturnal hypoxaemia among children with sickle cell anaemia in Mulago hospital.

Abstract

INTRODUCTION: Sickle cell anaemia is the commonest hereditary haemolytic disease in Uganda. It is often associated with multi organ complications such as vaso-occlusive crises, stroke and acute chest syndrome. Hypoxemia is generally recognised as one of the central precipitating events that begin the pathologic processes leading to the clinical problems in children with sickle cell disease. Day time and night time hypoxemia are considered biomarkers for painful crises, acute chest syndrome and stroke. A plausible pathogenic mechanism for this association is the role hypoxemia plays in activating pro-inflammatory and pro-adhesive cytokines in the microvasculature. Nocturnal hypoxemia is independently associated with stroke and painful crises in children with sickle cell disease. Screening these children for nocturnal hypoxemia could help clinicians identify those children at risk of stroke and frequent pain crises and institute measures to prevent or reduce these complications. METHODS: We carried out a cross sectional descriptive study to determine the prevalence and factors associated with nocturnal hypoxemia in children with sickle cell anaemia in mulago hospital. Eighty six children were enrolled and for each participant, a baseline day oxygen saturation and overnight pulse oximetry were done and blood analysed for complete blood count, malaria parasites and reticulocyte count. Hypoxemia was defined as oxygen saturation below 92%. RESULTS: The prevalence of nocturnal hypoxemia was 20%. Of the 86 patients, 27% had a history of snoring, 35% had been admitted in painful crisis in the past year and 20% had baseline day time Sp02 below 95%. Significant dips occurred in 28%. Factors independently associated with nocturnal hypoxemia were; baseline day Sp02 below 95% (p<0.001) and significant Sp02 dips (p=0.022). CONCLUSIONS: It is not easy to predict nocturnal hypoxemia clinically or by use of routine laboratory investigations. Screening children with sickle cell anaemia with day time oximetry could identify those at risk of nocturnal hypoxemia.