Importance of depth-enhanced optical methods for measuring cerebral hemodynamics during transient hypotension

Daniel Milej; Leena N. Shoemaker; Jigneshkumar Mistry; Keith St. Lawrence

doi:10.1117/12.2666077

9 August 2023 Importance of depth-enhanced optical methods for measuring cerebral hemodynamics during transient hypotension

Daniel Milej, Leena N. Shoemaker, Jigneshkumar Mistry, Keith St. Lawrence

Author Affiliations +

Proceedings Volume 12628, Diffuse Optical Spectroscopy and Imaging IX; 126280P (2023) https://doi.org/10.1117/12.2666077
Event: European Conferences on Biomedical Optics, 2023, Munich, Germany

Abstract

Optical methods are well-suited for non-invasive bedside brain imaging: near-infrared spectroscopy (NIRS) for measuring brain oxygenation and diffuse correlation spectroscopy (DCS) for measuring cerebral blood flow. However, data obtained with those optical techniques are prone to signal contamination from extracerebral tissue. This study aimed to evaluate extracerebral signal contamination in trNIRS/multidistance DCS data acquired during transient hypotension and assess suitable means of separating scalp and brain signals. An in-house built hybrid system was used to acquire oxygenation and blood flow data simultaneously during transient orthostatic hypotension induced by rapid-onset lower body negative pressure (LBNP). In nine healthy young adults, LBNP significantly decreased arterial blood pressure (-18 ± 14%), scalp blood flow (-36 ± 25%), and scalp tissue oxygenation (all p ≤ 0.04 vs baseline). In contrast, LBNP had no significant effect on cerebral blood flow or oxygenation. This finding was confirmed by transcranial Doppler ultrasound, which found no significant changes (-8 ± 16%) in middle cerebral artery blood velocity during LBNP. These results demonstrate the importance of using depth-enhanced methods when applying these optical technologies to physiological paradigms designed to test cerebral autoregulation that also affect systemic physiology.

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Daniel Milej, Leena N. Shoemaker, Jigneshkumar Mistry, and Keith St. Lawrence "Importance of depth-enhanced optical methods for measuring cerebral hemodynamics during transient hypotension", Proc. SPIE 12628, Diffuse Optical Spectroscopy and Imaging IX, 126280P (9 August 2023); https://doi.org/10.1117/12.2666077

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KEYWORDS

Hemodynamics

Optical testing

Oxygenation

Near infrared spectroscopy

Tissue optics

Brain

Cerebral blood flow

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