Introduction: Periventricular leucomalacia (PVL) is hypothesized to be due to an impaired autoregulation leading to ischemia of the periventricular white matter. The aim of this study was to examine if hypotension or hypoxemia leads to a relatively decreased blood flow to the cerebral white matter in preterm infants.

Patients: 24 infants with a median birth weight 860 g (range 550-2680) and a median gestational age of 26weeks (26-32), 7 had a mean arterial blood pressure (MAP) in the range 22-30 mmHg, 7 had blood oxygen saturation (SAT) in the range 71-80% and 10 had MAP over 31 mmHg and SAT more than 85%.

Methods: 99mTc labelled HMPAO and single photon computer tomography. MAP below 31 mmHg was measured intraarterially. SAT was measured by pulse oximetry.

Results: A linear correlation between MAP and the relative flow to the white matter was seen when MAP was below 31 mmHg (p=0.02, r2=0.60) but absent when MAP was over this limit (p=0.61, r2=0.06). The cortical flow and the flow to the basal ganglia, cerebellum and the brainstem were unchanged. During hypoxemia the relative flow to all regions was unchanged.

Conclusion: The study confirms the hypothesis, that hypotension may cause brain damage in preterm infants due to an impaired autoregulation. However, hypoxemia did not lead to changes in regional cerebral blood flow.