Department of Neuroscience, Università degli Studi di Torino, Turin, Italy.
Department of Electronics and Telecommunications, Politecnico di Torino, Turin, Italy.
Sci Rep. 2022 Feb 9;12(1):2155. doi: 10.1038/s41598-022-05863-y.
The influence of large vessels on near infrared spectroscopy (NIRS) measurement is generally considered negligible. Aim of this study is to test the hypothesis that changes in the vessel size, by varying the amount of absorbed NIR light, could profoundly affect NIRS blood volume indexes. Changes in haemoglobin concentration (tHb) and in tissue haemoglobin index (THI) were monitored over the basilic vein (BV) and over the biceps muscle belly, in 11 subjects (7 M - 4 F; age 31 ± 8 year) with simultaneous ultrasound monitoring of BV size. The arm was subjected to venous occlusion, according to two pressure profiles: slow (from 0 to 60 mmHg in 135 s) and rapid (0 to 40 mmHg maintained for 30 s). Both tHb and THI detected a larger blood volume increase (1.7 to 4 fold; p < 0.01) and exhibited a faster increase and a greater convexity on the BV than on the muscle. In addition, NIRS signals from BV exhibited higher correlation with changes in BV size than from muscle (r = 0.91 vs 0.55, p < 0.001 for THI). A collection of individual relevant recordings is also included. These results challenge the long-standing belief that the NIRS measurement is unaffected by large vessels and support the concept that large veins may be a major determinant of blood volume changes in multiple experimental conditions.
大血管对近红外光谱（NIRS）测量的影响通常被认为可以忽略不计。本研究旨在验证以下假设，即通过改变吸收的近红外光量来改变血管大小，可以深刻影响 NIRS 血液体积指数。在 11 名受试者（7 名男性-4 名女性；年龄 31±8 岁）中，同时监测肱静脉（BV）和二头肌肌腹的大小，监测血红蛋白浓度（tHb）和组织血红蛋白指数（THI）的变化。手臂接受静脉闭塞，根据两种压力曲线：缓慢（从 0 到 60mmHg 在 135s 内）和快速（0 到 40mmHg 维持 30s）。tHb 和 THI 均检测到更大的血液体积增加（1.7 到 4 倍；p<0.01），并且在 BV 上的增加更快，凸度更大。此外，BV 的 NIRS 信号与 BV 大小的变化相关性高于肌肉（THI 为 r=0.91 比 0.55，p<0.001）。还包括一组个体相关记录。这些结果挑战了 NIRS 测量不受大血管影响的长期观点，并支持大静脉可能是多种实验条件下血液体积变化的主要决定因素的概念。
