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A Comprehensive Educational Website (established 1998)

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

Bhavani Shankar Kodali MD

Updated September 2022

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Zachary BeattyGlenveiw Fire DepartmentHey Doc,
First I have to say thanks for putting this website together. It is very informative and helpful. Now, my question. I am a firefighter/paramedic with the Glenview Fire Department in Illinois. We often have guys asking about the "ventilating to a number" utilizing the end tidal CO2 value during cardiac arrest. From my basic understanding of capnography, during cardiac arrest we should follow the AHA guidelines for ventilation due to the fact that the end tidal CO2 value is not only a function of the ventilation rate, but also one of cardiac output and cellular metabolism. An example I hear brought up a lot, is a pt in arrest that is not within that "optimum" 35-45 mm hg range. The question is then do we ventilate according to the end tidal value or to AHA recommendations. My thinking is that if the pt has a lower value, it is due to the decrease in cardiac output (as we know cardiac output during CPR is not as good as the "real thing") and the decrease in cellular metabolism. Therefore, the lower value in this case is not due to ventilating the pt to much and does not mean that we need to adjust our ventilation rate to the value. I feel that the utilization of capnography to determine ventilation rates is more applicable to the pt that is "alive." However, I also understand that if we have a derangement in the value with a pt that is alive, we still need to examine if the problem is a ventilation rate problem or if it stems from a cardiac output or cellular metabolism problem. This is my basic understanding when it comes to this portion of capnography, and if I am wrong, please feel free to correct me. Once again, I appreciate the effort that is put into this site and I look forward to hearing from you!

Very Respectfully,

Zachary P Beatty
Glenview Fire Department