Rapid Recovery Of Cerebral Blood Content And Oxygenation In Adults From Time-Resolved Near-Infrared Spectroscopy
Abstract
Patient neurological outcomes following cardiac surgery are improved when near-infrared spectroscopy (NIRS) is used to optimize intraoperative cerebral oxygen delivery. However, current NIRS analysis methods have difficulties monitoring adult brains due to contamination from the extracerebral layer (ECL).
The objective of this thesis is to develop a time-resolved (TR) NIRS data analysis method for monitoring adult cerebral oxygen saturation (ScO2) and total hemoglobin (HbT) by assuming the head is composed of two layers – the ECL and the brain. We tested the validity of this assumption using in silico data from an adult human head using two approaches; a few-wavelength, single detector method, and a hyperspectral, two-detector method that does not require prior knowledge of exact ECL thickness. Both methods were able to recover ScO2 and HbT with mean percent differences below 3%. Additionally, the hyperspectral method requires only 0.22 seconds per measurement, enabling quasi-real-time adult neuromonitoring.