Measurement of cerebral oxygen consumption in the human neonate using near infrared spectroscopy: Cerebral oxygen consumption increases with advancing gestational age

Abstract

Measurements of cerebral oxygen consumption (CV(O2)) may improve our understanding of cerebral oxygenation, but there are few published data for sick neonates. Although cerebral maturation is associated with an increase in cerebral glucose consumption, the relationship between CV(O2) and increasing gestational age has not previously been assessed in humans. The aims of this study were to evaluate a noninvasive method for the estimation of CV(O2) in the neonate using near infrared spectroscopy, and to investigate the relationship between gestational age and CV(O2). Twenty babies who were undergoing intensive care in the neonatal period were studied. Cerebral hemoglobin flow (CHbF) and cerebral venous oxyhemoglobin saturation (CS(VO2)) were measured using near infrared spectroscopy. Arterial oxyhemoglobin saturation was measure by pulse oximetry (Sp(O2)). CV(O2) was calculated from the equation: CV(O2) = CHbF x (Sp(O2) - Sv(O2) x 4. The median (range) CV(O2) was 0.9 (0.52-1.76) mL·100 g-1 min-1. There was an increase in CV(O2) with advancing gestational age (n = 20, ρ = 0.55, p = 0.014). We conclude that CV(O2) can be estimated in sick neonates using noninvasive optical methods. The values obtained are similar to those obtained in other studies by more invasive methods, and are in agreement with values which would be expected from the known rate of cerebral glucose consumption in neonates. Mean (SD) CV(O2) at 24-26 wk was 0.5 (0.18) mL·100 g-1 min-1 and rose with increasing gestation to term by 0.03 mL·100 g-1 min-1 per wk.