Volume 29 Issue S3 | Journal of Biomedical Optics

Journal of Biomedical Optics

VOL. 29 · NO. S3 | June 2024

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Special Issue on Pulse Oximetry: 50 Years of Inventions and Discoveries in Biomedical Optics (1)

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Special Issue on Pulse Oximetry: 50 Years of Inventions and Discoveries in Biomedical Optics

Assessing changes in regional cerebral hemodynamics in adults with a high-density full-head coverage time-resolved near-infrared spectroscopy device

Farah Kamar, Leena Shoemaker, Rasa Eskandari, Daniel Milej, Darren Drosdowech, John Murkin, Keith St. Lawrence, Jason Chui, Mamadou Diop

Journal of Biomedical Optics, Vol. 29, Issue S3, S33302, (May 2024) https://doi.org/10.1117/1.JBO.29.S3.S33302

TOPICS: Surgery, Brain, Hemodynamics, Near infrared spectroscopy, Oxygenation, Tunable filters, Head, Skin, Bandpass filters, Wavelets

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Significance

Cerebral oximeters have the potential to detect abnormal cerebral blood oxygenation to allow for early intervention. However, current commercial systems have two major limitations: (1) spatial coverage of only the frontal region, assuming that surgery-related hemodynamic effects are global and (2) susceptibility to extracerebral signal contamination inherent to continuous-wave near-infrared spectroscopy (NIRS).

Aim

This work aimed to assess the feasibility of a high-density, time-resolved (tr) NIRS device (Kernel Flow) to monitor regional oxygenation changes across the cerebral cortex during surgery.

Approach

The Flow system was assessed using two protocols. First, digital carotid compression was applied to healthy volunteers to cause a rapid oxygenation decrease across the ipsilateral hemisphere without affecting the contralateral side. Next, the system was used on patients undergoing shoulder surgery to provide continuous monitoring of cerebral oxygenation. In both protocols, the improved depth sensitivity of trNIRS was investigated by applying moment analysis. A dynamic wavelet filtering approach was also developed to remove observed temperature-induced signal drifts.

Results

In the first protocol (28±5 years; five females, five males), hair significantly impacted regional sensitivity; however, the enhanced depth sensitivity of trNIRS was able to separate brain and scalp responses in the frontal region. Regional sensitivity was improved in the clinical study given the age-related reduction in hair density of the patients (65±15 years; 14 females, 13 males). In five patients who received phenylephrine to treat hypotension, different scalp and brain oxygenation responses were apparent, although no regional differences were observed.

Conclusions

The Kernel Flow has promise as an intraoperative neuromonitoring device. Although regional sensitivity was affected by hair color and density, enhanced depth sensitivity of trNIRS was able to resolve differences in scalp and brain oxygenation responses in both protocols.

Significance

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