Cerebral blood flow is independent of mean arterial blood pressure in preterm infants undergoing intensive care.
OBJECTIVE
Preterm infants are often presumed to have a pressure passive cerebral circulation implying that a low mean arterial blood pressure (MABP) results in reduced cerebral perfusion. The aim of this study was to determine whether cerebral blood flow (CBF) was compromised in preterm infants whose MABP fell below 30 mm Hg (4 kPa).


METHODS
Thirty preterm infants undergoing intensive care were studied within the first 24 hours of life. CBF was measured using near infrared spectroscopy. The infants were analyzed in two groups on the basis of their MABP at the time of study: group 1 had a MABP below 30 mm Hg and group 2 more than 30 mm Hg. CBF in the two groups was compared.


RESULTS
There was no significant difference in the mean CBF between the two groups. In group 1 the median MABP was 27.2 mm Hg (range, 23.7-29.9 mm Hg) and CBF was 13.9 (standard deviation, +/-6.9) mL . 100 g-1 . min-1. In group 2 the median MABP was 35.3 mm Hg (range, 30.1-39.3 mm Hg) and CBF was 12.3 (standard deviation, +/-6.4) mL . 100 g-1 . min-1. Mortality and incidence of cranial ultrasound scan abnormalities were also not significantly different.


CONCLUSIONS
These results indicate that preterm infants undergoing intensive care are able to maintain adequate cerebral perfusion at a MABP in the range of 23.7 to 39.3 mm Hg.
Department of Paediatrics, University College London School of Medicine, London, UK.
L
L
Tyszczuk
J
J
Meek
C
C
Elwell
J S
JS
Wyatt
D001724:Birth Weight; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001921:Brain / Q000098:blood supply*; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D005865:Gestational Age; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000503:physiopathology*; D015931:Intensive Care, Neonatal; D008297:Male; D010100:Oxygen / Q000097:blood; D010108:Oxyhemoglobins / Q000378:metabolism; D012016:Reference Values; D019265:Spectroscopy, Near-Infrared
D010108:Oxyhemoglobins; D002245:Carbon Dioxide; D010100:Oxygen