Normal values of cerebral blood flow velocities in neonates

Abstract

Introduction. There was used color Doppler ultrasonography (cD-USI), allowing simultaneous examination of parenchymal and vascular cerebral structures. The evaluation of blood flow velocities in cerebral arteries is important in the assessment of cerebral circulation in hypoxic-ischaemic and haemorrhagic brain damage in neonates. Objective. The aim of this study was to estimate normal values of cerebral blood flow velocities (CBFV) and Doppler indices - pulsatility index (PI) and resistance index (RI) - in the anterior cerebral artery (ACA) during the first days of life in infants. Methods. CBFV, PI and RI were obtained during the first week of life with cD-US in 70 infants divided in four groups of gestational age (GA): ≤28 gestational weeks (GW); 29-32 GW; 33-36 GW; and ≥37 GW. Infants with congenital malformations, severe perinatal asphyxia, cerebral haemorrhagic lesion, DAP or severe hypotension were excluded. Results. The mean GA of infants was 34.5±5.5 GW (range 26-40 GW) and the mean birth weight (BW) was 2540±950 g (range 750-4000 g). In the 1st group of 10 infants, ≤28 GW, the mean BW was 950±110 g and values of RI were 0.59±0.10 and PI 1.06±0.080. In the 2nd group of 20 infants, 29-32 GW, the mean BW was 1350±290 g and values of RI were 0.60±0.10 and PI 1.10±0.15. In the 3rd group of 20 infants, 33-36 GW, the mean BW was 1950±750 g and values of RI were 0.63±0.08 and PI 1.15±0.30. In the 4th group of 20 infants, ≥37 GW, the mean BW was 3540±950 g and values of RI were 0.65±0.05 and PI 1.18±0.35. Conclusion. Values of CBFV progressively increase with GA and BW due to progressive increase of cardiac output, blood pressure and closing of ductus arteriosus. Values of RI and PI gradually increase with GA and BW as a result of progressive maturation and opening of vascular cerebral bed with a reduction of the cerebrovascular resistance.

Keywords

• color Doppler ultrasonography
• cerebral blood flow velocities
• neonates