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Influence of skin blood flow and source‐detector distance on near‐infrared spectroscopy‐determined cerebral oxygenation in humans
Author(s) -
Hirasawa Ai,
Yanagisawa Shintaro,
Tanaka Naoki,
Funane Tsukasa,
Kiguchi Masashi,
Sørensen Henrik,
Secher Niels H.,
Ogoh Shigehiko
Publication year - 2015
Publication title -
clinical physiology and functional imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.608
H-Index - 67
eISSN - 1475-097X
pISSN - 1475-0961
DOI - 10.1111/cpf.12156
Subject(s) - medicine , forehead , blood flow , oxygenation , hemodynamics , nuclear medicine , near infrared spectroscopy , cerebral blood flow , laser doppler velocimetry , blood pressure , cardiology , anesthesia , anatomy , optics , physics
Summary Most near‐infrared spectroscopy ( NIRS ) apparatus fails to isolate cerebral oxygenation from an extracranial contribution although they use different source‐detector distances. Nevertheless, the effect of different source‐detector distances and change in extracranial blood flow on the NIRS signal has not been identified in humans. This study evaluated the extracranial contribution, as indicated by forehead skin blood flow (Sk BF ) to changes in the NIRS ‐determined cerebral oxyhaemoglobin concentration (O 2 Hb) by use of a custom‐made multidistance probe. Seven males (age 21 ± 1 year) were in a semi‐recumbent position, while extracranial blood flow was restricted by application of four different pressures (+20 to +80 mmHg) to the left temporal artery. The O 2 Hb was measured at the forehead via a multidistance probe (source‐detector distance; 15, 22·5 and 30 mm), and Sk BF was determined by laser Doppler. Heart rate and blood pressure were unaffected by application of pressure to the temporal artery, while Sk BF gradually decreased ( P <0·001), indicating that extracranial blood flow was manipulated without haemodynamic changes. Also, O 2 Hb gradually decreased with increasing applied pressure ( P <0·05), and the decrease was related to that in Sk BF ( r = 0·737, P <0·01) independent of the NIRS source to detector distance. These findings suggest that the NIRS ‐determined cerebral oxyhaemoglobin is affected by change in extracranial blood flow independent of the source‐detector distance from 15 to 30 mm. Therefore, new algorithms need to be developed for unbiased NIRS detection of cerebral oxygenation.