Two-thirds of out-of-hospital cardiac arrest patients, who survive to hospital admission, die in the hospital from neurological injuries related to cerebral hypoperfusion. Hyperspectral near infrared spectroscopy (hNIRS) is a noninvasive technique that measures the major chromophores in the brain, such as oxygenated hemoglobin, deoxygenated hemoglobin and cytochrome C oxidase ([CCO]), an intracellular marker of oxygen consumption. We have demonstrated that hNIRS is feasible and can detect changes in cerebral oxygenation and metabolism in patients undergoing transcatheter aortic valve insertion (TAVI) – a procedure that temporarily induces sudden hypotension and hypoperfusion that mimics cardiac arrest. Using multi-distance hNIRS, we found that while measured regional oxygen saturation (rSO2) changes resulted mainly from the extra-cerebral tissues, [CCO] changes during cardiac arrests occurred mainly in the brains of patients. We also applied the hNIRS algorithm based on the “2-layer model” to the data to measure cerebral oxygen saturation and [CCO] in patients during the procedure.
In this series of animal experiments on resuscitation after cardiac arrest we had a unique opportunity to measure
hyperspectral near-infrared spectroscopy (hNIRS) parameters directly on the brain dura, or on the brain through the
intact pig skull, and simultaneously the muscle hNIRS parameters. Simultaneously the arterial blood pressure and carotid
and femoral blood flow were recorded in real time using invasive sensors. We used a novel hyperspectral signalprocessing
algorithm to extract time-dependent concentrations of water, hemoglobin, and redox state of cytochrome c
oxidase during cardiac arrest and resuscitation. In addition in order to assess the validity of the non-invasive brain
measurements the obtained results from the open brain was compared to the results acquired through the skull. The
comparison of hNIRS data acquired on brain surface and through the adult pig skull shows that in both cases the
hemoglobin and the redox state cytochrome c oxidase changed in similar ways in similar situations and in agreement
with blood pressure and flow changes. The comparison of simultaneously measured brain and muscle changes showed
expected differences. Overall the results show feasibility of transcranial hNIRS measurements cerebral parameters
including the redox state of cytochrome oxidase in human cardiac arrest patients.