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% confidence interval], 92.5 [92.0-93.0]) than in SC disease (96.7[96.5-96.9]) or AA controls (97.1 [96.8-97.3]). Inhalation of 100% oxygen in SS patients with O2 saturations below 90% consistently increased saturation to 99-100%. In SS disease, SpO2 correlated positively with haemoglobin and fetal haemoglobin and negatively with reticulocyte counts but not with MCHC, MCV or bilirubin level. Mean SpO2 in SS subjects with a normal alpha globin gene complement (mean [SD], 91.7 [3.9]%) was lower than in heterozygotes (93.4 [4.0]%) or homozygotes (96.1 [3.0]%) for alpha+ thalassaemia, the effects of alpha-thalassaemia not being explained by differences in haemoglobin or MCHC. In SS disease, SpO2 levels were not associated with age (within this age range), sex, number of sick clinic visits or number of hospital admissions. Higher SpO2 levels were associated with greater height and weight, 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 values during acute complications.

Assessment of Oxygen Saturation Using Pulse Oximetry in Patients with Steady State HbSS

“…reports [9,13]. Contrary to reports of lower SpO 2 levels in male patients with steady state SCA [11,13], our male and female patients had comparable levels of SpO 2 .…”

“…There are reports of increased risk for central nervous system events with hypoxemia, whereas, higher oxygen saturations (SpO 2 ) was associated with less frequent acute chest syndrome [5,6]. Many studies showed haemoglobin desaturation to be common in patient with sickle cell anaemia (SCA) even at steady state [7][8][9], and high prevalence of hypoxemia has been documented in children with SCA [10,11]. With improved care, the median survival of patients with SCA has risen, and therefore the prevalence of chronic organ diseases encountered in the adult population has also increased.…”

Daytime steady‐state haemoglobin desaturation is a risk factor for overt stroke in children with sickle cell anaemia

“…That is, Hb was not associated with stroke when controlling for other factors. Because Hb correlates with SpO 2 (Homi et al, 1997;Setty et al, 2003;Quinn & Ahmad, 2005), we suggest that Hb concentration may be a proxy for SpO 2 , which could be the proximate risk factor for stroke. Prior studies of risk factors for stroke that did not include SpO 2 as a predictor may have identified a confounding relationship between Hb and stroke because Hb correlates with SpO 2 .…”

“…Finally, although we found no clear associations between co-morbid conditions and Hb desaturation, there was no systematic screening for such causes. However, desaturation is a known complication of SS itself (Rackoff et al, 1993;Homi et al, 1997;Needleman et al, 1999;Setty et al, 2003;Quinn & Ahmad, 2005).…”

“…Steady-state haemoglobin (Hb) desaturation is a common finding in SS that is often thought to be benign (Rackoff et al, 1993;Homi et al, 1997;Quinn & Ahmad, 2005). Chronic Hb desaturation could contribute to the risk of stroke by perturbing endothelial function (Setty et al, 2003) and limiting oxygen delivery to the brain.…”