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

How can I convert SpO2 to PaO2?

PaO2 is a measurement of the partial pressure of oxygen in arterial blood and requires an arterial blood gas (ABG). In many settings an ABG may not be practical or feasible, and thus the established mathematical relationship between SpO2 and PaO2 can be used. There is a distinct relationship between PaO2 and SpO2 which is illustrated by the Oxygen Dissociation Curve (see image). This relationship can be altered by many factors (e.g. temperature, FDG, pH) but generally follows the classic “S-shape” graph with PaO2 on the x axis and oxygen saturation on the y axis. This online calculator can be used to convert SpO2 to PaO2.

References: Lifebox Pulse Oximetry Learning Module; Oxygen Calculator Website

Keywords: PaO2, oxygen dissociation curve, conversion

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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’