Pulse oximetry in a cohort study of sickle cell disease

ABSTRACT

Oxygen saturation was determined by pulse oximetry in a representative sample of Jamaican patients with steady state sickle cell disease in a cohort study from birth. There were 220 with homozygous sickle cell (SS) disease and 142 with sickle cell-haemoglobin C (SC) disease aged 9-18 years, and 122 with a normal haemoglobin (AA) genotype aged 15-18 years. Pulse oximetry (SpO2) values were lower in SS disease (mean [95 percent confidence interval]), 92.5 [92.0-93.3]. Inhalation of 100 percent oxygen in SS patients with 02 saturations below 90 percent consistency increased saturation to 99-100 percent. In SS disease, Sp02 correlated positively with haemoglobin and fetal haemoglobin and negatively with reticulocyte counts but not MCHC, MCV or bilirubin level. Mean Sp02 in SS subjects with a normal alpha globin gene complement (mean[SD], 91.7 [3.9]percent) was lower than in heterozygotes (93.4 [4.0] percent) or homozygotes (96.1 [3.0] percent) for alpha+thalassaemia, the effects of alpha-thalassaemia not being explained by differences in haemoglobin or MCHC. In SS disease, Sp02 levels were not associated with age (within this age range), sex, number of sick clinic visits or number of hospital admissions. Higher Sp02 levels were associated with greater heights and weights, more frequent painful crises and less frequent acute chest syndrome, but these associations were not significant after adjustment for haemoglobin level. Desaturation is common in steady-state SS disease and knowledge of the individual's steady-state value may be important in the interpreting low value during acute complications.(AU)