Physiology and Technical Aspects of ETCO2 Monitoring

Don’t treat the numbers!

ETCO2 is mainly determined by the:

1) Amount of perfusion to the lungs

2) CO2 concentration in the blood

Poor perfusion to the lungs (deadspace) will cause a disparity between the numerical ETCO2, and what the actual arterial CO2 concentration is. 

So, ETCO2 MUST be interpreted in light of the patients pathophysiological state. 

Papers mentioned in the podcast:

The Effectiveness of Oxygen Delivery and Reliability of Carbon Dioxide Waveforms: A Crossover Comparison of 4 Nasal Cannulae

https://emcrit.org/wp-content/uploads/2011/10/efficacy-of-NC-for-o2-and-etco2.pdf

Most accurate method of measuring ETCO2 during non-invasive ventilation

http://www.physio-control.com/uploadedfiles/learning/clinical-topics/capno_during_non-invasive_ventilation.pdf

PHEMCAST episode on ETCO2

https://phemcast.co.uk/2017/09/

ACC/AHA recommendation on using ETCO2 as a marker of evaluating systemic perfusion in patients with assist devices

http://www.acc.org/latest-in-cardiology/ten-points-to-remember/2017/05/29/15/17/cardiopulmonary-resuscitation-in-adults-and-children

Now for the podcast!