Determinants of cerebral fractional oxygen extraction using near infrared spectroscopy in preterm neonates.

Cerebral fractional oxygen extraction (FOE) represents the balance between cerebral oxygen delivery and consumption. This study aimed to determine cerebral FOE in preterm infants during hypotension, during moderate anemia, and with changes in the PaCO2. Three groups of neonates were studied: stable control neonates (n = 43), anemic neonates (n = 46), and hypotensive neonates (n = 19). Cerebral FOE was calculated from the arterial oxygen saturation measured by pulse oximetry, and cerebral venous oxygen saturation was measured using near infrared spectroscopy with partial jugular venous occlusion. Mean ± SD cerebral FOE was similar in control (0.292 ± 0.06), anemic (0.310 ± 0.08; P = 0.26), and hypotensive (0.278 ± 0.06; P = 0.41) neonates. After anemic neonates were transfused, mean ± SD cerebral FOE decreased to 0.274 ± 0.05 (P = 0.02). There was a weak negative correlation with the hemoglobin concentration (n = 89, r = −0.24, P = 0.04) but not with the hemoglobin F fraction (n = 56, r = 0.24, P = 0.09). ...