J Clin Ultrasound 18:167-171, MarchiApril 1990
Acceleration Time in Cerebral Arteries of Preterrn and Term Infants Margot van de Bor, MD, PhD, Frans J. Walther, MD, PhD, Maureen E. Sims, MD
Abstract: We measured the acceleration times in the pericallosal, internal carotid, and basilar arteries with two-dimensional/pulsed Doppler ultrasonography in 145 nondistressed preterm and term infants between 24 and 48 hours after birth. In all three arteries we found a linear relationship between the acceleration time and menstrual age or birth weight. These findings were determined by changes in peak systolic flow velocity, but not by changes in mean arterial blood pressure or cardiac output. We speculate on an important role for cerebral autoregulation in the acceleration time variations between newborn infants of differing menstrual ages and birth weights. Indexing Words: Acceleration time Cerebral blood flow velocity Neonates
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Doppler ultrasonography provides the opportunity to record blood flow velocity waveforms in arterial vessels. The acceleration time of the blood flow velocity waveform is the time from start to peak of the waveform. Acceleration times in the pulmonary artery and the aorta have been studied in second and third trimester fetuses, children, and adults.'-4 No correlation was found between menstrual age and acceleration time in the aorta of fetuses between 16 weeks and 40 weeks.ls2 In children and adults, acceleration times in the pulmonary artery and aorta are related with mean arterial blood pressure: as mean arterial pressure increases, acceleration time becomes shorter. Nondistressed preterm and term newborn infants have been shown to have cerebral autoreg~ l a t i o n . ~Studies '~ by Greisen et al.7 and Younkin et a1.8 indicate that cerebral blood flow is independent of mean arterial pressure in preterm infants. In the presence of cerebral autoregulation, the acceleration time in the cerebral arteries would be independent of mean arterial pressure and cardiac output. To test this hypothFrom the Division of Neonatology, Department of Pediatrics, University of Southern California School of Medicine, Los Angeles County-USC Medical Center, Los Angeles, California. For reprints contact Frans J Walther, MD, PhD, Dept. of Pediatrics, King/Drew Medical Center, 12021 S. Wilmington Ave, Los Angeles, CA 90059. 0 1990 by John Wiley & Sons, Inc. CCC 0091-2751/90/030167-05 $04.00
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esis we measured acceleration time in the pericallosal, internal carotid, and basilar arteries, mean arterial pressure, and cardiac output in 145 nondistressed newborn infants of 25 weeks to 42 weeks menstrual age. PATIENTS AND METHODS
One hundred and forty-five appropriate for menstrual age newborn infants with ages ranging from 25 weeks to 42 weeks born at Women's Hospital of Los Angeles County- University of Southern California Medical Center were enrolled into the study after written informed maternal consent was obtained. Infants with intrauterine distress (fetal heart rate pattern abnormalities, cord pH
Acceleration Time in Cerebral Arteries of Preterrn and Term Infants Margot van de Bor, MD, PhD, Frans J. Walther, MD, PhD, Maureen E. Sims, MD
Abstract: We measured the acceleration times in the pericallosal, internal carotid, and basilar arteries with two-dimensional/pulsed Doppler ultrasonography in 145 nondistressed preterm and term infants between 24 and 48 hours after birth. In all three arteries we found a linear relationship between the acceleration time and menstrual age or birth weight. These findings were determined by changes in peak systolic flow velocity, but not by changes in mean arterial blood pressure or cardiac output. We speculate on an important role for cerebral autoregulation in the acceleration time variations between newborn infants of differing menstrual ages and birth weights. Indexing Words: Acceleration time Cerebral blood flow velocity Neonates
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Doppler ultrasonography provides the opportunity to record blood flow velocity waveforms in arterial vessels. The acceleration time of the blood flow velocity waveform is the time from start to peak of the waveform. Acceleration times in the pulmonary artery and the aorta have been studied in second and third trimester fetuses, children, and adults.'-4 No correlation was found between menstrual age and acceleration time in the aorta of fetuses between 16 weeks and 40 weeks.ls2 In children and adults, acceleration times in the pulmonary artery and aorta are related with mean arterial blood pressure: as mean arterial pressure increases, acceleration time becomes shorter. Nondistressed preterm and term newborn infants have been shown to have cerebral autoreg~ l a t i o n . ~Studies '~ by Greisen et al.7 and Younkin et a1.8 indicate that cerebral blood flow is independent of mean arterial pressure in preterm infants. In the presence of cerebral autoregulation, the acceleration time in the cerebral arteries would be independent of mean arterial pressure and cardiac output. To test this hypothFrom the Division of Neonatology, Department of Pediatrics, University of Southern California School of Medicine, Los Angeles County-USC Medical Center, Los Angeles, California. For reprints contact Frans J Walther, MD, PhD, Dept. of Pediatrics, King/Drew Medical Center, 12021 S. Wilmington Ave, Los Angeles, CA 90059. 0 1990 by John Wiley & Sons, Inc. CCC 0091-2751/90/030167-05 $04.00
-
esis we measured acceleration time in the pericallosal, internal carotid, and basilar arteries, mean arterial pressure, and cardiac output in 145 nondistressed newborn infants of 25 weeks to 42 weeks menstrual age. PATIENTS AND METHODS
One hundred and forty-five appropriate for menstrual age newborn infants with ages ranging from 25 weeks to 42 weeks born at Women's Hospital of Los Angeles County- University of Southern California Medical Center were enrolled into the study after written informed maternal consent was obtained. Infants with intrauterine distress (fetal heart rate pattern abnormalities, cord pH
