Article

Cerebral tissue hemoglobin saturation in children with sickle cell disease

Division of Hematology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio. .
Pediatric Blood & Cancer (Impact Factor: 2.56). 11/2012; 59(5):881-7. DOI: 10.1002/pbc.24227
Source: PubMed

ABSTRACT Desaturation of hemoglobin (Hb) in cerebral tissue, a physiologic marker of brain vulnerable to ischemic injury, can be detected non-invasively by transcranial oximetry. Absolute cerebral oximetry has not been studied in sickle cell disease (SCD), a group at very high risk of cerebral infarction in whom prevention of brain injury is key.
We measured absolute Hb saturation in cerebral tissue (S(CT) O(2) ) in children with SCD using near-infrared spectrophotometry and investigated the contributions of peripheral Hb saturation (S(P) O(2) ), hematologic measures, cerebral arterial blood flow velocity, and cerebral arterial stenosis to S(CT) O(2) . We also assessed the effects of transfusion.
We studied 149 children with SCD (112 HbSS/Sβ(0) ; 37 HbSC/Sβ(+) ). S(CT) O(2) was abnormally low in 75% of HbSS/Sβ(0) and 35% of HbSC/Sβ(+) patients. S(CT) O(2) (mean ± SD) was 53.2 ± 14.2 in HbSS/Sβ(0) and 66.1 ± 9.2% in SC/Sβ(+) patients. S(CT) O(2) correlated with age, sex, Hb concentration, reticulocytes, Hb F, and S(P) O(2) , but not transcranial Doppler arterial blood flow velocities as continuous measures. In multivariable models, S(P) O(2) , Hb concentration, and age were significant independent determinants of S(CT) O(2) . Cerebral vasculopathy was associated with ipsilateral cerebral desaturation. Transfusion increased S(CT) O(2) and minimized the inter-hemispheric differences in S(CT) O(2) due to vasculopathy.
Cerebral desaturation, a physiologic marker of at-risk brain, is common in SCD, more severe in HbSS/Sβ(0) patients, and associated with peripheral desaturation, more severe anemia, and increasing age. Cerebral oximetry has the potential to improve the identification of children with SCD at highest risk of neurologic injury and possibly serve as a physiologic guide for neuroprotective therapy. Pediatr Blood Cancer 2012; 59: 881-887. © 2012 Wiley Periodicals, Inc.

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    • "Prior research, however, shows that although the oxygen affinity of haemoglobin S is decreased in its polymerised state and in hypoxic conditions, it is near normal in its tetrameric state and in patients in normoxia (Abdu et al., 2008; Fabry et al., 2001), like the steady state SCA patients in our study. In children, lower peripheral oxygen saturation was positively correlated with cerebral desaturation (Quinn and Dowling, 2012). In adults, however, when the oxygen saturation of venous blood of HbSS patients was directly tested, it was found to be similar to that of HbAA controls, probably because increased blood flow in SCA leads to relatively lower oxygen extraction (Gladwin et al., 1999). "
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