Advanced Cardiovascular Life Support (ACLS) Practice Exam

What does a PETCO2 level of 8 mm Hg indicate during CPR?

1. Effective chest compressions are being delivered

2. Capnography is not functioning properly

3. Chest compressions may not be effective

4. Ventilations are being delivered adequately

The correct answer is: Chest compressions may not be effective

A PETCO2 level of 8 mm Hg during CPR indicates that chest compressions may not be effective, as it reflects the overall perfusion of the patient and the ability to return carbon dioxide from the tissues back to the lungs. A low PETCO2 level suggests that there is inadequate blood flow and, therefore, poor cardiac output. Since PETCO2 is a measure of the carbon dioxide present in exhaled air, a reading this low typically indicates that the compressions are not generating sufficient circulation to facilitate the exchange of gases, which means that the heart may not be effectively pumping blood during resuscitation efforts. In terms of other choices, a normal PETCO2 level is expected to be higher during effective compressions, and a reading of 8 mm Hg suggests poor compression technique or other underlying issues rather than indicating proper function of capnography or adequacy of ventilations. Thus, this reinforces the understanding that such a low PETCO2 level is a significant concern during CPR, pointing towards the need to assess and improve the quality of compressions being delivered.