Nocturnal hypoxaemia and central-nervous-system events in sickle-cell disease.
BACKGROUND
Central-nervous-system (CNS) events, including strokes, transient ischaemic attacks, and seizures are common in sickle-cell disease. Stroke can be predicted by high velocities in the internal-carotid or middle-cerebral arteries on transcranial doppler ultrasonography. We tested the hypothesis that nocturnal hypoxaemia can predict CNS events better than clinical or haematological features, or transcranial doppler sonography.


METHODS
We screened 95 hospital-based patients with sickle-cell disease (median age 7.7 years [range 1.0-23.1]), but without previous stroke, with transcranial doppler and overnight pulse oximetry. Follow-up continued for a median of 6.01 (0.11-8.54) years.


RESULTS
19 patients had CNS events (six ischaemic and one haemorrhagic stroke, eight transient ischaemic attacks, and four seizures). Mean overnight oxygen saturation ([SaO(2)] hazard ratio 0.82 per 1% increase [95% CI 0.71-0.93]; p=0.003) and higher internal-carotid or middle-cerebral artery velocity (1.02 for every increase of 1 cm/s [1.004-1.03]; p=0.009) were independently associated with time to CNS event. After accounting for mean SaO(2), artery velocity, and haemoglobinopathy, high haemoglobin concentration was also associated with an increased risk of CNS event (1.7 per g/dL, [1.18-2.43]; p=0.004). Dips suggestive of obstructive sleep apnoea did not predict CNS events, and adenotonsillectomy seemed to have no effect, although the CI were wide and clinically important effects cannot be excluded.


CONCLUSIONS
Screening for, and appropriate management of, nocturnal hypoxaemia might be a safe and effective alternative to prophylactic blood transfusion for primary prevention of CNS events in sickle-cell disease.
Kirkham
F J
FJ
Neurosciences Unit, Institute of Child Health, University College London, London, UK. F.kirkham@ich.ucl.ac.uk
Hewes
D K
DK
Prengler
M
M
Wade
A
A
Lane
R
R
Evans
J P
JP
D000293:Adolescent; D000328:Adult; D000755:Anemia, Sickle Cell / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001783:Blood Flow Velocity / Q000502:physiology; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D002940:Circadian Rhythm / Q000502:physiology; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007223:Infant; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D010092:Oximetry; D017286:Polysomnography; D012640:Seizures / Q000000981:diagnostic imaging* / Q000503:physiopathology; D020521:Stroke / Q000000981:diagnostic imaging* / Q000503:physiopathology; D017585:Ultrasonography, Doppler, Transcranial