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1426 AN ENHANCED METHOD TO MONITOR CEREBRAL BLOOD FLOW IN NEWBORNS: NON-FAST FOURIER TRANSFORM (FFT) SPECTRAL ANALYSIS OF DOPPLER BLOOD FLOW VELOCITY

We have developed, using non-FFT signal processing techniques, a new method of analysis of continuous wave (CW) Doppler ultrasound signals obtained by placing a probe over the anterior fontanelle of the newborn. The best orientation of the probe with respect to the vessel is identified using headphones. Three electrocardiograph (EKG) electrodes are placed over the chest. The Doppler and EKG audio signals are recorded simultaneously on a tape recorder, digitized by computer, transferred to an IBM Personal Computer where they are analyzed, averaged and displayed. An “averaged” signal consists of the previous 5 signals. Using this method the relative quantities of red blood cells moving at different velocities can be discerned and are represented by different colors on the color monitor. We have studied 14 well and 2 sick term infants. The well infants were studied on three consecutive days. Both right and left sides, and several probe sizes and probe frequencies were studied. The signal is quite reproducible between left and right sides, between studies in the same infant on different days, as well as between infants. We have determined the spectral pattern in term infants, and have, in one sick infant, identified asymmetry between R & L when there was facial pallor during a prostaglandin infusion. This qualitative method should prove useful in monitoring cerebral blood flow in newborns.