Clinical Pearls: Waveform Capnography

End tidal carbon dioxide (ETCO2) measures exhaled carbon dioxide, it therefore reflects the efficacy with which CO2 is pumped back to the lungs (indirect measurement of cardiac output) and then exhaled (ventilation). Waveform Capnography is a continuous tracing, or waveform, of ETCO2. It is very useful when assessed as a trend.