Relationship between blood pressure, cerebral electrical activity, cerebral fractional oxygen extraction, and peripheral blood flow in very low birth weight newborn infants.

摘要

There is uncertainty about the level of systemic blood pressure required tomaintain adequate cerebral oxygen delivery and organ integrity. This prospective,observational study on 35 very low birth weight infants aimed to determine themean blood pressure (MBP) below which cerebral electrical activity, peripheralblood flow (PBF), and cerebral fractional oxygen extraction (CFOE) are abnormal. Digital EEG, recorded every day on the first 4 d after birth, were analyzed a) byautomatic spectral analysis, b) by manual measurement of interburst interval, andc) qualitatively. CFOE and PBF measurements were performed using near-infraredspectroscopy and venous occlusion. MBP was measured using arterial catheters. Themedian (range) of MBP recorded was 32 mm Hg (16-46). The EEG became abnormal atMBP levels below 23 mm Hg: a) the relative power of the delta (0.5-3.5 Hz)frequency band was decreased, b) interburst intervals were prolonged, and c) all four qualitatively abnormal EEG (low amplitude and prolonged interburstintervals) from four different patients were recorded below this MBP level. Theonly abnormally high CFOE was measured at MBP of 20 mm Hg. PBF decreased at MBPlevels between 23 and 33 mm Hg. None of the infants in this study developedcystic periventricular leukomalacia. One infant (MBP, 22 mm Hg) developedventricular dilatation after intraventricular hemorrhage. The EEG and CFOEremained normal at MBP levels above 23 mm Hg. It would appear that cerebralperfusion is probably maintained at MBP levels above 23 mm Hg.