Noninvasive in vivo measurement of venous blood pH during exercise using near-infrared reflectance spectroscopy
Department of Anesthesiology
Medical Subject Headings
Adult; Blood Chemical Analysis; Calibration; Data Interpretation, Statistical; Exercise; Female; Hand Strength; Humans; Hydrogen-Ion Concentration; Least-Squares Analysis; Male; Principal Component Analysis; Spectroscopy, Near-Infrared
Anesthesiology | Chemistry
Blood pH is an important indicator of anaerobic metabolism in exercising muscle. This paper demonstrates multivariate calibration techniques that can be used to produce a general pH model that can be applied to spectra from any new subject without significant prediction error. Tissue spectra (725 approximately 880 nm) were acquired through the skin overlying the flexor digitorum profundus muscle on the forearms of eight healthy subjects during repetitive hand-grip exercise and referenced to the pH of venous blood drawn from a catheter placed in a vein close to the muscle. Calibration models were developed using multi-subject partial least squares (PLS) and validated using subject-out cross-validation after the subject-to-subject spectral variations were corrected by mathematical preprocessing methods. A combination of standard normal variate (SNV) scaling and principal component analysis loading correction (PCALC) successfully removed most of the subject-to-subject variations and provided the most accurate prediction results.
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Citation: Appl Spectrosc. 2007 Feb;61(2):223-9. Link to article on publisher's site