Abstract
Six chronically instrumented, late gestation (119-136 days) fetal sheep were subjected to 30 minutes of total cerebral ischaemia in utero. Changes in the concentration of oxidised cytochrome aa3 ([CytO2]), oxyhemoglobin ([HbO2]) and deoxyhaemoglobin ([Hb]) were measured using near infrared spectroscopy (NIRS) through optodes surgically secured to the fetal skull. Cortical impedance (CI) was recorded simultaneously as a measure of cortical cytotoxic oedema. Measurements commenced prior to the insult and continued subsequently for 96 hours. Brains were examined histopathologically at the end of the study. Data were analysed by one way repeated measures ANOVA and linear regression and significant results (p ≤0.05) are presented (mean±SEM). An initial fall in [CytO2] occurred during the insult (−0.6±0.3μmol.l−1) and reperfusion post insult (−1.4 ± 0.4 μmol.−1). A further fall in [CytO2] commenced 23±3 hours after the insult and continued progressively to a maximum of −4.4±l.l μmol.l−1 at 60±10 hours. Changes in [CytO2] were not temporally related to alterations in [HbO2], [Hb] or CI. The late fall in [CytO2;] was positively related to % increase in CI following the insult and % neuronal loss.
CONCLUSION: Following transient ischaemia, a maximum late fall in [CytO2], as measured by NIRS, correlated with the severity of cerebral damage.
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Marks, K., Mallard, C., Roberts, I. et al. 148 CHANGES IN THE CEREBRAL CONCENTRATION OF OXIDIZED CYTOCHROME aa, FOLLOWING ISCHAEMIA IN FETALSHEEP, AS MEASURED BY NEAR INFRARED SPECTROSCOPY. Pediatr Res 36, 27 (1994). https://doi.org/10.1203/00006450-199407000-00148
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DOI: https://doi.org/10.1203/00006450-199407000-00148