Abstract
Cerebral autoregulation has been demonstrated in newborn animals. We studied the relationship between mean arterial pressure (MAP) and cerebral blood flow velocity (CBFV) in 90 stable preterm infants ≤32 weeks gestation. Mean (SD) gestational age was 28.9 (1.9) wks, birth weight 1,128 (230) grams, 5 min Apgar score 7.4 (0.9), and initial pH 7.36 (.08). All infants had been normoxic and normocarbic from birth onwards. Intracranial hemorrhage and patent ductus arteriosus were excluded. CBFV was determined at MAPs ranging from 27-50 mm Hg. Using 2-D/Doppler ultrasound, we obtained CBFV waveforms from the pericallosal (PCA), internal carotid (ICA), and basilar (BA) arteries between 12-72 hours of age. Peak systolic, end diastolic, and mean (MFV) flow velocities were derived from 3 consecutive cardiac cycles.
A linear relationship between MAP and MFV was found in all 3 arteries: r=.76 in the PCA, r=.73 in the ICA, and r=.70 in the BA (p<.001). Multiple regression analysis showed that the MFV was solely determined by MAP and not by PaCO2, PaO2, heart rate or mean airway pressure.
We conclude that between 27-50 mm Hg MAP a linear relationship between MAP and MFV exists in 3 major intracranial arteries. These data raise questions about the ability of the very preterm infant to regulate cerebral blood flow.
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van de Bor, M., Walther, F. & Sims, M. CEREBRAL AUTOREGULATION IN PRETERM INFANTS. Pediatr Res 26, 504 (1989). https://doi.org/10.1203/00006450-198911000-00029
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DOI: https://doi.org/10.1203/00006450-198911000-00029