Abstract
To the Editor.— The determination of cerebral blood velocity in the newborn infant using transfontanel Doppler ultrasound has been discussed in detail in two recent commentaries.1,2 Whereas the use of the Doppler effect to determine blood velocity is well accepted, it is apparent that considerable controversy exists regarding the ability of this technique to measure cerebral blood flow in the neonate.1,2 In particular, the hemodynamic significance of the pulsatility index (PI) remains unclear. It has been suggested that the PI reflects cerebral vascular resistance based on the assumption that, as resistance is altered, primarily diastolic, and not systolic, blood velocity will change.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
