Abstract
Background: Ensuring the adequacy of cerebral oxygen delivery to meet metabolic demand is important in the brain orientated intensive care of preterm infants. Spatially resolved near-infrared spectroscopy allows continuous quantitative assessment of the mean cerebral oxygen saturation (SmcO2). This is a composite measure dependent on cerebral oxygen delivery and extraction. The aim of this study was to measure SmcO2 in a cohort of preterm infants in the first 36 hours of life.
Methods: Seventeen preterm infants born at a median (range) gestational age of 25 (23–32) weeks were studied. The median age at study was 10 (3–35) hours following delivery. All infants were receiving ventilatory support. Four infants had evidence of intracranial haemorrhage on cranial ultrasound examination. A NIRO300 spectrophotometer was used (Hamamatsu Photonics K.K, Japan) with the optodes placed over the parietal region. Continuous SmcO2 data was collected for 30 minutes. Other physiological variables were simultaneously recorded, including the mean arterial blood pressure (MABP) and the partial pressure of carbon dioxide (PaCO2) from a transcutaneous electrode. In 7 infants studied within the first 12 hours of life repeated measures were made at 34 (24–59) hours. The relationship between SmcO2 and gestational age, postnatal age, MABP and PaCO2 was analysed using Pearson Product Moment Correlation. Consecutive measurements were analysed using a t-test (SigmaStat, SPSS Inc).
Results: The median SmcO2 was 57.4 (43–77.7)%. There was a significant relationship between SmcO2 and gestational age(correlation coefficient 0.6, P=0.01). There was no significant relationship between SmcO2 and MABP, PaCO2 and age at study. There was no difference in SmcO2 between infants with and without intraventricular haemorrhage. In the infants in whom consecutive measurements were made there was a significant increase in SmcO2 between first and second measurement (t=−2.5, P<0.03).
Conclusion: SmcO2 is lower in extremely preterm infants and increases with gestational age. Consecutive measurements reveal an increase in SmcO2 in the first 72 hours of life consistent with an increase in cerebral blood flow. Cerebral metabolic rate is known to be low in the preterm infant and to increase with gestational age. In the extremely preterm infant it is likely that the low cerebral oxygen saturation is a consequence of low cerebral perfusion and as a consequence these infants are more vulnerable to hypoxic-ischaemic cerebral injury in the first day of life.
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Austin, T., Henty, J., Meek, J. et al. 10 Mean Cerebral Oxygen Saturation Increases with Gestational Age in Preterm Infants. Pediatr Res 56, 465 (2004). https://doi.org/10.1203/00006450-200409000-00033
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DOI: https://doi.org/10.1203/00006450-200409000-00033