Wardle S P, Yoxall C W, Weindling A M
Department of Child Health, University of Liverpool, England.
J Cereb Blood Flow Metab. 2000 Feb;20(2):272-9. doi: 10.1097/00004647-200002000-00008.
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). In the hypotensive neonates, there was no relationship between cerebral FOE and blood pressure (n = 19, r = 0.34, P = 0.15). There was a significant negative correlation between cerebral FOE and PaCO2 within individuals (n = 14, r = -0.63, P = 0.01), but there was no relationship between individuals (n = 14, r = 0, P = 1). Cerebral FOE was not significantly altered in neonates with either mild anemia or hypotension. There were, however, changes in cerebral FOE when physiological changes occurred over a relatively short period: Cerebral FOE decreased after blood transfusion and increased with decreasing PaCO2. As no change in cerebral FOE was seen during hypotension, it was speculated that cerebral oxygen delivery may have been maintained by cerebral blood flow autoregulation.
脑部分氧摄取率（FOE）代表了脑氧输送与消耗之间的平衡。本研究旨在确定早产儿在低血压、中度贫血以及动脉血二氧化碳分压（PaCO2）变化时的脑FOE。研究了三组新生儿：稳定对照组新生儿（n = 43）、贫血新生儿（n = 46）和低血压新生儿（n = 19）。通过脉搏血氧饱和度测定仪测量动脉血氧饱和度来计算脑FOE，并使用部分颈静脉闭塞的近红外光谱法测量脑静脉血氧饱和度。对照组（0.292±0.06）、贫血组（0.310±0.08；P = 0.26）和低血压组（0.278±0.06；P = 0.41）新生儿的平均±标准差脑FOE相似。贫血新生儿输血后，平均±标准差脑FOE降至0.274±0.05（P = 0.02）。与血红蛋白浓度呈弱负相关（n = 89，r = -0.24，P = 0.04），但与血红蛋白F分数无关（n = 56，r = 0.24，P = 0.09）。在低血压新生儿中，脑FOE与血压之间无相关性（n = 19，r = 0.34，P = 0.15）。个体内脑FOE与PaCO2之间存在显著负相关（n = 14，r = -0.63，P = 0.01），但个体之间无相关性（n = 14，r = 0，P = 1）。轻度贫血或低血压的新生儿脑FOE无明显改变。然而，当在相对较短的时间内发生生理变化时，脑FOE会发生改变：输血后脑FOE降低，随着PaCO2降低而升高。由于在低血压期间未观察到脑FOE的变化，推测脑氧输送可能通过脑血流自动调节得以维持。
