Continuous Waveform Capnography

The AHA states that continuous waveform capnography in addition to clinical assessment is the most reliable method of confirming and monitoring correct placement of an endotracheal tube.

Under normal conditions PETCO2 range between 35 to 40 mm Hg. During untreated cardiac arrest CO2 continues to be produced in the body, but there is no CO2 delivery to the lungs. Under these conditions PETCO2 will approach zero. However, with initiation of CPR, the cardiac compressions improves the cardiac output and the delivery of CO2 delivery to the lungs. Thus, if ventilation is relatively constant, the PETCO2 values correlate well with cardiac output during CPR.

The AHA notes that a persistently low PETCO2 values (<10 mm Hg) during CPR in intubated patients suggest that the return of spontaneous circulation is unlikely.

Monitoring PETCO2 trends during CPR has the potential to guide individual optimization of compression depth and rate and to detect fatigue in the provider performing compressions

During resuscitation, if PETCO2 abruptly increases to a normal value (35 to 40 mm Hg), it is reasonable to consider that the patient has had a return of spontaneous circulation.

Circulation.2010; 122: S729-S767 doi: 10.1161/​CIRCULATIONAHA.110.9709

PETCO2 below normal values

PETCO2