Cerebral mitochondrial and regional haemoglobin saturation patterns during and after profound hypothermic circulatory arrest in neonatal piglets

Total circulatory arrest (TCA) in deep hypothermia used in corrective surgery of complex cardiovascular malformations in children has been claimed to cause brain injury and altered psychomotor development.Near infrared spectroscopy (NIRS) allows in vivo determination of changes in cerebral oxygenated (HbO2), deoxygenated (Hb), and total haemoglobin (Hbt; the sum of Hb + HbO2). Relative changes in the redox state of cytochrome oxydase (cyt.aa3), the terminal enzyme in the mitochondrial respiratory chain, may provide information about the availability of oxygen at cellular level. The new tissue oxygenation index (TOI) provides information on the global tissue oxygenation. Measurement of protein S-100 is used as a marker of astroglial cell injury. Thus, change in intravascular and intracellular oxygenation states were measured by NIRS during and after TCA in a neonatal piglet model.