Pulse Oximetry FAQ

This FAQ has been compiled by our team of experts. Please submit your questions at the bottom of this page!

Pulse Oximetry FAQ Physiology of pulse ox

What is spectrophotometry?

Spectrophotometry is a type of quantitative measurement technique that is used to measure the reflection or transmission properties of a substance as a function of wavelength. Every type of substance absorbs light over a specific range of wavelengths. This type of measurement allows us to assess the intensity of light that a substance (such as hemoglobin in blood) absorbs, and therefore has clinical and bioengineering applications.

Clinically, spectrophotometry is used in pulse oximeters to determine the proportion of oxygenated hemoglobin in arterial blood. Since different wavelengths of light are absorbed by oxygenated and deoxygenated blood, pulse oximeters can use this technique to determine a patient’s peripheral oxygen saturation (SpO2).

Keywords: spectroscopy, spectrophotometry, wavelength, light

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Healthy Human Performance Tests

To meet 2017 ISO standards (80601-2-61) or 2013 FDA guideline adherence for clinical use, pulse oximeter performance must be tested in healthy humans in a laboratory setting. Independent device testing for the Open Oximetry Project follows our protocol consistent with ISO and FDA. Only devices labeled as ‘verified’ or ‘failed’ have been independently tested by the Open Oximetry Project.
All other devices listed show data from manufacturers or published literature and have not been confirmed by the Open Oximetry team. Scoring criteria will be modified based on evolving data on this topic. See the table below for scoring criteria for this category:

No Data

No Data

1 (red)

>4%

2 (red)

<4%

AND/OR Data suggesting Arms for dark skin color of >4%

AND/OR Data suggesting Arms for PI<1 in dark or light skin color of >4%

3 (yellow)

<4%

AND/OR Data suggesting Arms for dark skin color of 3-4%

AND/OR Data suggesting Arms for PI<1 in dark or light skin color of 3-4%

4 (green)

<3%

AND No data for or against performance problems in darker skin colors

AND No data for or against performance problems in low perfusion

5 (green)

<3%

AND Extended testing beyond ISO/FDA recommendations Criteria TBD April 2023

AND Extended testing beyond ISO/FDA recommendations Criteria TBD April 2023

* only independently tested devices by OpenOximetry (Hypoxia Lab and Clinimark Lab) get labeled as ‘verified’