Interrelationship of Oxygen Supply by Hepatic Artery and Portal Vein: Rapid Analysis of Ischemia-Reflow-Induced Changes in Hepatic Oxygenation in Experimental and Clinical Subjects by Tissue Near-Infrared Spectroscopy

1994 ◽  
Vol 26 (6) ◽  
pp. 342-352 ◽  
Author(s):  
A. Tokuka ◽  
A. Tanaka ◽  
T. Kitai ◽  
N. Yanabu ◽  
S. Mori ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Portal Vein ◽  
Hepatic Artery ◽  
Near Infrared Spectroscopy ◽  
Oxygen Supply ◽  
Near Infrared ◽  
Rapid Analysis ◽  
Induced Changes

Rapid analysis of packaging laminates by near-infrared spectroscopy

The Analyst ◽  
1985 ◽  
Vol 110 (6) ◽  
pp. 643 ◽  
Author(s):  
Anthony M. C. Davies ◽  
Alex Grant ◽  
Gillian M. Gavrel ◽  
Robert V. Steeper
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Rapid Analysis

scholarly journals Perfusion Changes at the Forehead Measured by Photoplethysmography during a Head-Down Tilt Protocol

Biosensors ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 71
Author(s):  
Tomas Ysehak Abay ◽  
Kamran Shafqat ◽  
Panayiotis A. Kyriacou
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Venous Blood ◽  
Arterial Oxygen ◽  
Large Variability ◽  
Large Vein ◽  
The Subject ◽  
Induced Changes

Photoplethysmography (PPG) signals from the forehead can be used in pulse oximetry as they are less affected by vasoconstriction compared to fingers. However, the increase in venous blood caused by the positioning of the patient can deteriorate the signals and cause erroneous estimations of the arterial oxygen saturation. To date, there is no method to measure this venous presence under the PPG sensor. This study investigates the feasibility of using PPG signals from the forehead in an effort to estimate relative changes in haemoglobin concentrations that could reveal these posture-induced changes. Two identical reflectance PPG sensors were placed on two different positions on the forehead (above the eyebrow and on top of a large vein) in 16 healthy volunteers during a head-down tilt protocol. Relative changes in oxygenated ( Δ HbO 2 ), reduced ( Δ HHb) and total ( Δ tHb) haemoglobin were estimated from the PPG signals and the trends were compared with reference Near Infrared Spectroscopy (NIRS) measurements. Also, the signals from the two PPG sensors were analysed in order to reveal any difference due to the positioning of the sensor. Δ HbO 2 , Δ HHb and Δ tHb estimated from the forehead PPGs trended well with the same parameters from the reference NIRS. However, placing the sensor over a large vasculature reduces trending against NIRS, introduces biases as well as increases the variability of the changes in Δ HHb. Forehead PPG signals can be used to measure perfusion changes to reveal venous pooling induced by the positioning of the subject. Placing the sensor above the eyebrow and away from large vasculature avoids biases and large variability in the measurements.

Near-Infrared Spectroscopic Measurement of Lactate in Human Plasma

2000 ◽  
Vol 54 (2) ◽  
pp. 300-304 ◽  
Author(s):  
Denis Lafrance ◽  
Larry C. Lands ◽  
Laura Hornby ◽  
David H. Burns
Keyword(s):  
Infrared Spectroscopy ◽  
Human Plasma ◽  
Near Infrared Spectroscopy ◽  
Standard Error ◽  
Near Infrared ◽  
Rapid Analysis ◽  
Spectroscopic Measurement ◽  
Physiological Status ◽  
Clinical Use ◽  
Plasma Samples

A method based on near-infrared spectroscopy (NIRS) is presented, which provides a rapid analysis of lactate in plasma. In order to test the technique, NIRS analysis and enzymatic measurements were made on plasma samples taken from exercising humans. A correlation coefficient of 0.995 and a standard error of 0.51 mmol/L were found between the enzymatic and the NIR results. This standard error is within the range needed for real-time monitoring of lactate in plasma for exercising studies. In the future, this technique may provide a valuable tool to assess physiological status for research and clinical use.

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