Transcranial Doppler ultrasound: a review of the physical principles and major applications in critical care.
Transcranial Doppler (TCD) is a noninvasive ultrasound (US) study used to measure cerebral blood flow velocity (CBF-V) in the major intracranial arteries. It involves use of low-frequency (≤2 MHz) US waves to insonate the basal cerebral arteries through relatively thin bone windows. TCD allows dynamic monitoring of CBF-V and vessel pulsatility, with a high temporal resolution. It is relatively inexpensive, repeatable, and portable. However, the performance of TCD is highly operator dependent and can be difficult, with approximately 10-20% of patients having inadequate transtemporal acoustic windows. Current applications of TCD include vasospasm in sickle cell disease, subarachnoid haemorrhage (SAH), and intra- and extracranial arterial stenosis and occlusion. TCD is also used in brain stem death, head injury, raised intracranial pressure (ICP), intraoperative monitoring, cerebral microembolism, and autoregulatory testing.
University Hospital South Manchester, Southmoor Road, Wythenshawe, Manchester M23 9LT, UK.
Jawad
J
Naqvi
Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, UK.
Kok Hooi
KH
Yap
Royal Oldham Hospital, Rochdale Road, Manchester OL1 2JH, UK.
Gulraiz
G
Ahmad
University Hospital South Manchester, Southmoor Road, Wythenshawe, Manchester M23 9LT, UK.
Jonathan
J
Ghosh