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Characterizing near‐infrared spectroscopy signal under hypercapnia
Author(s) -
Yang HoChing Shawn,
Liang Zhenhu,
Vike Nicole L.,
Lee Taylor,
Rispoli Joseph V.,
Nauman Eric A.,
Talavage Thomas M.,
Tong Yunjie
Publication year - 2020
Publication title -
journal of biophotonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 66
eISSN - 1864-0648
pISSN - 1864-063X
DOI - 10.1002/jbio.202000173
Subject(s) - hypercapnia , cerebral blood flow , vasoactive , anesthesia , perfusion , cerebral perfusion pressure , near infrared spectroscopy , cardiology , chemistry , medicine , neuroscience , psychology , acidosis
Abstract Vasoactive stress tests (i.e. hypercapnia, elevated partial pressure of arterial CO 2 [PaCO 2 ]) are commonly used in functional MRI (fMRI), to induce cerebral blood flow changes and expose hidden perfusion deficits in the brain. Compared with fMRI, near‐infrared spectroscopy (NIRS) is an alternative low‐cost, real‐time, and non‐invasive tool, which can be applied in out‐of‐hospital settings. To develop and optimize vasoactive stress tests for NIRS, several hypercapnia‐induced tasks were tested using concurrent‐NIRS/fMRI on healthy subjects. The results indicated that the cerebral and extracerebral reactivity to elevated PaCO 2 depended on the rate of the CO 2 increase. A steep increase resulted in different cerebral and extracerebral reactivities, leading to unpredictable NIRS measurements compared with fMRI. However, a ramped increase, induced by ramped‐CO 2 inhalation or breath‐holding tasks, induced synchronized cerebral, and extracerebral reactivities, resulting in consistent NIRS and fMRI measurements. These results demonstrate that only tasks that increase PaCO 2 gradually can produce reliable NIRS results.