Abstract
A new non-invasive method for repeated estimation of cerebral blood flow (CBF) in infants and children durning non-ppulsatile cardiopulmonary bypass (CPB) is described. The method is derived from the Fick principle, using oxyhaemoglobin (HbO2) as a non-diffusible tracer. A sudden change in O2 flow in to the oxygenator causes a change in arterial saturation (SaO2) which is measured by an optical oximeter, and in cerebral [HbO2], which is detected by NIRS: CBF is calculated from the expression:
where k is a constant reflecting the molecular weight of haemoglobin and tissue density.[11] is the arterial haemoglobin concentration. CBF was measured on 16 occasions in 6 children undergoing CPB, median age 5.3 (range 4-62) months. Near-infrared light was transmitted from and returned to the spectrometer by fibre optic cables applied to the head. After a stable baseline of 88-%% SaO2 (median 94%) had been achieved for at least 10 seconds, a rise in SaO2 of 2-10% (median 5%) was induced. Values for CBF of 9-54 ml.100g−1.min were obtained. Preliminary data from two children showed that at full pump How median CBF was 47 (range 41-54) ml 100g−1.min−1 and at half flow was 2.1 (range 22-29) ml.100g−1.min−1. The method warrants further study but suggests that routine, repealed and non-invasive measurements of CBF during CPB may now be possible.
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Fallen, P., Roberts, I., Maynard, R. et al. CEREBRAL BLOOD FLOW MEASURED BY NEAR INFRARED SPECTROSCOPY (NIRS) IN CHILDREN UNDERGOING OPEN HEART SURGERY. Pediatr Res 35, 259 (1994). https://doi.org/10.1203/00006450-199402000-00031
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DOI: https://doi.org/10.1203/00006450-199402000-00031
