Follow Capnography / Bhavani Shankar Kodali     Twitter   Youtube

A Comprehensive Educational Website (established 1998)

Designed, Produced, and maintained (Edition 12, 2022) by 

Bhavani Shankar Kodali MD

Updated September 2022

Effect of Oxygen

Physics of capnography

Bhavani Shankar Kodali MD


Factors affecting IR Spectrography



Oxygen does not absorb IR light

Oxygen does not absorb IR light
Oxygen does have affect via collision broadening effect
Oxygen has  collision broadening affect




How does oxygen affect CO2 measurements?

Oxygen does not absorb IR light
Oxygen produces collision broadening phenomena that can cause falsely low CO2 measurements.


Although oxygen does not absorb IR light it may indirectly affect the absorption by C02 by collision with the C02 molecules and broadening the absorption peak. While it does not cause as large an effect as N20, oxygen causes a falsely low C02 reading. Some units automatically correct or have a user-actuated electronic offset for the concentration oxygen encountered.1


1. Carbon dioxide monitors. Health Devices 1986;15:255-85.

previous      main         next