Expired CO2 Measurement in Intubated or Spontaneously Breathing Patients from the Emergency Department
Summary
This video describes how to perform CO2 measurement in intubated as well as spontaneously breathing patients. The main clinical indications refer to emergency situations: (1) verifying adequate positioning of an endotracheal tube; (2) achieving normocapnia in trauma patients; (3) monitoring ventilation in the case of procedural sedation.
Abstract
Carbon dioxide (CO2) along with oxygen (O2) share the role of being the most important gases in the human body. The measuring of expired CO2 at the mouth has solicited growing clinical interest among physicians in the emergency department for various indications: (1) surveillance et monitoring of the intubated patient; (2) verification of the correct positioning of an endotracheal tube; (3) monitoring of a patient in cardiac arrest; (4) achieving normocapnia in intubated head trauma patients; (5) monitoring ventilation during procedural sedation. The video allows physicians to familiarize themselves with the use of capnography and the text offers a review of the theory and principals involved. In particular, the importance of CO2 for the organism, the relevance of measuring expired CO2, the differences between arterial and expired CO2, the material used in capnography with their artifacts and traps, will be reviewed. Since the main reluctance in the use of expired CO2 measurement is due to lack of correct knowledge concerning the physiopathology of CO2 by the physician, we hope that this explanation and the video sequences accompanying will help resolve this limitation.
Protocol
Discussion
Importance of CO2 for the Organism
Before exploring expired CO2 monitoring, it is essential to put into perspective the general role played by CO2 in the human body. Produced at a rate of approximately 200 ml per minute, CO2 is not just a wasted by-product of cellular metabolism. If our medullar chemoreceptors have the role of maintaining the arterial CO2 partial pressure (PaCO2) at 40mmHg, it is because CO2 has other functions in the organi…
Divulgations
The authors have nothing to disclose.
References
- Gravenstein, J. S., Jaffe, M. B., Paulus, D. A. . Capnography, Clinical aspects. , (2004).
- Kupnik, D., Skok, P. Capnometry in the prehospital setting: are we using its potential. Emerg Med J. 24, 614-617 (2007).
- Delorio, N. M. Continuous end-tidal carbon dioxide monitoring for confirmation of endotracheal tube placement is neither widely available nor consistently applied by emergency physicians. Emerg Med J. 22, 490-493 (2005).
- Burton, J. H., Harrah, J. D., Germann, C. A. Does end-tidal carbon dioxide monitoring detect respiratory events prior to current sedation monitoring practices?. Acad Emerg Med. 13, 500-504 (2006).
- Fletcher, R., Jonson, B., Cumming, G., Brew, J. The concept of deadspace with special reference to the single breath test for carbon dioxide. Br J Anaesth. 53, 77-78 (1981).
