Exhaled Carbon Dioxide
EtCO2 is a measure of exhaled carbon dioxide. In the cardiac arrest setting, this measurement is taken via a sensor attached to the endotracheal tube. The normal value is between 35 and 40 mmHg.
Carbon dioxide is produced as a waste product of the production of energy in our body’s cells. It is moved from the cells to the blood stream, then moved from the blood stream into the airspaces of the lungs where the exhalation phase of breathing removes the carbon dioxide from the lungs.
Carbon dioxide production continues for several minutes after cardiopulmonary arrest as the cells utilize oxygen remaining in the blood stream.
It is usual for initial EtCO2 readings to be high initially after intubation as the carbon dioxide that has built up in the lungs is exhaled.
After the first minute or two of CPR, EtCO2 provides an indication of the body’s response to resuscitation. If CPR is adequate and blood is circulating through the circulatory system, the EtCO2 will remain closer to normal. If there is impaired blood circulating or cell death, the EtCO2 will decrease.
An EtCO2 below 10mmHg after approximately 20 minutes of resuscitation efforts is an indicator the resuscitation will not be successful and for termination.
The EtCO2 readings demonstrated an expected pattern of initial near normal EtCO2 measurement followed by a rapid decline over several minutes, indicating the resuscitation will not be successful.