Blood Oxygen Measurement

Farmer, J.C.

doi:10.1201/9781420050790.ch3

Cited by 7 publications

(4 citation statements)

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“…The noninvasive transcutaneous PaO 2 electrode has low accuracy and requires heating of the skin to 43°C–44°C. 3 , 4 The noninvasive technique of pulse oximetry 5 – 7 for the assessment of SaO 2 is the subject of the current review. After describing the fundamentals of the technique, the review discusses the origins and the level of inaccuracy in oxygen-saturation measurement by pulse oximetry, as well as the clinical significance of the error in SaO 2 measurement, particularly in newborns.…”

Section: Arterial Oxygen Saturationmentioning

confidence: 99%

Pulse oximetry: fundamentals and technology update

Nitzan

Romem

Koppel

2014

MDER

301

252

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Oxygen saturation in the arterial blood (SaO2) provides information on the adequacy of respiratory function. SaO2 can be assessed noninvasively by pulse oximetry, which is based on photoplethysmographic pulses in two wavelengths, generally in the red and infrared regions. The calibration of the measured photoplethysmographic signals is performed empirically for each type of commercial pulse-oximeter sensor, utilizing in vitro measurement of SaO2 in extracted arterial blood by means of co-oximetry. Due to the discrepancy between the measurement of SaO2 by pulse oximetry and the invasive technique, the former is denoted as SpO2. Manufacturers of pulse oximeters generally claim an accuracy of 2%, evaluated by the standard deviation (SD) of the differences between SpO2 and SaO2, measured simultaneously in healthy subjects. However, an SD of 2% reflects an expected error of 4% (two SDs) or more in 5% of the examinations, which is in accordance with an error of 3%–4%, reported in clinical studies. This level of accuracy is sufficient for the detection of a significant decline in respiratory function in patients, and pulse oximetry has been accepted as a reliable technique for that purpose. The accuracy of SpO2 measurement is insufficient in several situations, such as critically ill patients receiving supplemental oxygen, and can be hazardous if it leads to elevated values of oxygen partial pressure in blood. In particular, preterm newborns are vulnerable to retinopathy of prematurity induced by high oxygen concentration in the blood. The low accuracy of SpO2 measurement in critically ill patients and newborns can be attributed to the empirical calibration process, which is performed on healthy volunteers. Other limitations of pulse oximetry include the presence of dyshemoglobins, which has been addressed by multiwavelength pulse oximetry, as well as low perfusion and motion artifacts that are partially rectified by sophisticated algorithms and also by reflection pulse oximetry.

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Section: Arterial Oxygen Saturationmentioning

confidence: 99%

Pulse oximetry: fundamentals and technology update

Nitzan

Romem

Koppel

2014

MDER

301

252

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“…51 It should be noted that Beer's law is insufficient in circumstances with significant reflectance, scattering and autofluorescence; however, within a specific range of concentrations, it has been and can be used as an approximation. 114 It is important to note that the portion of the intensity absorbed by a substance in a solution at a specific wavelength is a constant value characteristic of the material. This constant value is known as the “ absorptivity ε ” and can be related to the absorbance, as shown in eqn (1).Another essential parameter is the “ absorption coefficient , μ a ”, which determines how deep light of a particular wavelength can go into the sample before being completely absorbed.…”

Section: Bilirubin Spectroscopymentioning

confidence: 99%

“…However, Beer's law, hence DWL, can be used as an approximation to minimize scattering and other interfering background noise. 114,122…”

Section: Bilirubin Spectroscopymentioning

confidence: 99%

70 years of bilirubin sensing: towards the point-of-care bilirubin monitoring in cirrhosis and hyperbilirubinemia

Ndabakuranye

Burchall

et al. 2022

Sens. Diagn.

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“…This technique is based on the principle of the Beer-Lambert law [6] , [7] . Therefore, before any device for measuring

using an optical process could be invented, various chemical processes were first proposed, such as Van Slyke’s method, the mixing syringe method, and methods using the principle of oxidation, for example, the Clark electrode and the galvanic electrode [8] , [9] , [10] , [11] . However, chemical processes require chemical expertise, and any such process requires a blood sample from the patient, which must first be sampled from the patient’s body.…”

Section: Introductionmentioning

confidence: 99%