While we’ve used colorimetric capnography for years to confirm ETT placement, not all ICU providers are as familiar with waveform capnography. It offers significant benefits to the intubated and non-intubated patient alike.
Using waveform capnography to confirm ETT placement offers a benefit over colorimetric confirmation. during the peri-intubation period, while the patient is being ventilated via BVM, there can be an accumulation of CO2 in the stomach so that it is possible to get color change on an esophageal intubation. The use of waveform capnography prevents this. As carbon dioxide is not manufactured in the stomach, eventually the levels will fall. So, by trending the waveform over a few breaths, you should see a steady decrease in end-tidal CO2 over the course of a few breaths.
In addition to ETT positioning, ETCO2 has a number of other benefits including detecting displaced ETTs, monitoring effectiveness of ventilation in non-intubated patients, assessing ROSC during CPR, and much more. But essential to its use is understanding how to interpret the waveform and not just read the number. In this video, Obiajulu Anozie (@icuexplained) does a great job of explaining what the waveform means and how to use it in the ICU.