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Intra‐individual variation in blood flow velocities in cerebral arteries of children with sickle cell disease
Author(s) -
Brambilla Donald J.,
Miller Scott T.,
Adams Robert J.
Publication year - 2007
Publication title -
pediatric blood and cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.116
H-Index - 105
eISSN - 1545-5017
pISSN - 1545-5009
DOI - 10.1002/pbc.21142
Subject(s) - medicine , transcranial doppler , stroke (engine) , cerebral blood flow , cardiology , standard deviation , cerebral arteries , sickle cell anemia , disease , pediatrics , statistics , mechanical engineering , mathematics , engineering
Background Children with sickle cell disease (SCD) are at elevated risk of stroke. Risk increases with blood flow velocity in selected cerebral arteries, as measured by transcranial Doppler (TCD) ultrasound, and use of TCD to screen these patients is widely recommended. Interpretation of TCD results should be based on knowledge of intra‐individual variation in blood flow velocity, information not currently available for sickle cell patients. Procedures Between 1995 and 2002, 4,141 subjects, 2–16 years old, with homozygous SCD or Sβ 0 ‐thalasemmia and no history of stroke were screened with TCD, including 2,018 subjects screened in one clinical trial (STOP), 1,816 screened in another (STOP 2), and 307 screened in an interim ancillary prospective study. The 812 subjects with ≥2 examinations <6 months apart were selected for analysis, including 242 (29.8%) subjects with normal average velocities (i.e., <170 cm/sec), 350 (43.1%) subjects with conditional velocities (i.e., 170–199 cm/sec), and 220 (27.1%) subjects with abnormal velocities (i.e., ≥200 cm/sec). The intra‐subject standard deviation of TCD velocity was estimated from the difference between velocities at the first two interpretable examinations on each subject. Results An intra‐subject standard deviation of 14.9 cm/sec was obtained. Seven (0.9%) subjects had unusually large and unexplained differences between velocities at the two examinations (range of absolute differences: 69–112 cm/sec). Conclusions While stroke risk is well demonstrated to increase with increasingly abnormal TCD velocity, given the relatively large intra‐subject variability, one TCD examination is generally not sufficient to characterize stroke risk in this patient population. Pediatr Blood Cancer 2007;49:318–322. © 2007 Wiley‐Liss, Inc.