The risk of neurological injury for infants and children with cardiac and/or acute respiratory defects undergoing surgical procedures is considerable. This can be attributed to the fact that the specific surgical procedures are inevitably accompanied by periods of hypoxia/ischemia. Therefore, the application of specific monitoring to detect cerebral hypoxic conditions associated with neurological injury would both allow intervention on individual patients and drive refinements in strategies to reduce risk. Our studies are focused on children with intractable cardio-respiratory failure whose heart and lungs are supported on extracorporeal membrane oxygenation (ECMO). Establishing ECMO involves cannulation of the major vessels in the neck-internal jugular vein and carotid artery-maintaining and weaning from ECMO requires manipulation of ECMO flows, which can affect cerebral blood flow and potentially lead to neurologic complications. The long-term aim of the studies is to use an optical topography system to investigate topographic cerebral oxygenation changes in patients undergoing ECMO. However initially we are monitoring regional cerebral and peripheral tissue oxygenation using a dual channel system, with the aim of investigating the relationship between brain and peripheral tissue oxygenation during changes in ECMO related variables. We have used a dual channel near infrared system to measure changes in oxy-(HbO2) and deoxy-(HHb) haemoglobin concentrations, and tissue oxygenation index (TOI) on the forehead (cerebral) and calf (peripheral) of ECMO patients undergoing flow manipulations in the ECMO circuit. Power spectral density (PSD) and coherence analysis were performed on the HbO2 signal recorded at the two measurement sides in order to extract vasomotion, respiratory and cardiac oscillations [1]. |
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