[Intra-individual variation of cerebral blood flow velocity in sleeping and awake children]
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Insights
Cerebral blood flow velocities show significant variability in children, especially in the posterior cerebral artery and during restlessness. This variability is influenced by factors like hyperventilation and sleep, impacting autoregulation.
Area of Science:
- Pediatric Neurology
- Neurophysiology
- Cerebrovascular Physiology
Background:
- Intraindividual variability in cerebral blood flow velocities is a critical factor in pediatric neurovascular assessment.
- Understanding these variations is essential for accurate interpretation of Doppler ultrasound findings in children.
Purpose of the Study:
- To quantify intraindividual variability of middle and posterior cerebral artery blood flow velocities in children.
- To investigate the influence of factors such as restlessness, hyperventilation, and sleep on these velocities.
Main Methods:
- Continuous transcranial Doppler (TCD) monitoring was performed in 74 children during electroencephalogram (EEG) registration.
- Flow velocities were analyzed for variability, with specific attention to the middle and posterior cerebral arteries.
- The impact of induced hyperventilation and non-REM sleep stages on flow velocities was assessed.
Main Results:
- Significant intraindividual variability in cerebral blood flow velocities was observed.
- Posterior cerebral artery velocities exhibited higher variability than middle cerebral artery velocities.
- Restless children showed greater variability than calm children.
- Hyperventilation caused a 50% decrease, followed by a 130-140% increase post-hyperventilation.
- Variations exceeding 30% were noted during non-REM sleep, potentially due to reduced autoregulatory damping.
Conclusions:
- Cerebral blood flow velocity variability in children is substantial and influenced by physiological states.
- These findings underscore the importance of considering intraindividual variations in pathological conditions and during Doppler monitoring in pediatric patients.
Abstract:
A considerable intraindividual variability of blood flow velocities in the middle and posterior cerebral artery was found in 74 children by continuous transcranial Doppler recording during EEG registration. The coefficient of variation of the mean flow velocities in the posterior cerebral artery was higher than in the middle cerebral artery, and higher in restless children than in calm children. During hyperventilation the mean flow velocities decreased to about 50 per cent of the baseline values. They increased to 130-140 per cent of the baseline values after hyperventilation. Repeated variations of the velocities of more than 30 per cent of the baseline values were observed during non-REM sleep in the majority of the children. They may be caused by a lower damping of the cerebral autoregulatory response. The intraindividual variability of cerebral blood flow velocities in children has to be kept in mind in pathological conditions and during Doppler monitoring.