Which of the following is NOT a CPR breathing barrier?

In the context of CPR breathing barriers, the correct response identifies a device that is not designed specifically as a barrier to provide rescue breaths. Pocket masks and face shields are both considered CPR breathing barriers as they are intended to protect both the rescuer and the patient from direct contact while facilitating rescue breaths. The pocket mask covers the mouth and nose of the patient, offering a seal that helps deliver air effectively, while the face shield provides a barrier that allows for ventilation without direct mouth-to-mouth contact.

Ambu bags, or bag-valve-mask devices, serve a different function; they are used for providing positive pressure ventilation to patients who are not breathing or are in respiratory distress. While they are vital life-saving tools in advanced life support, they do not qualify as breathing barriers in the same category as pocket masks and face shields.

The device labeled as "BVMS," or bag-valve-mask systems, is often confused with bags used for ventilation but serves primarily the same purpose as other advanced ventilation techniques rather than acting as a barrier for CPR. Thus, the identification of Ambu bags clarifies their purpose in facilitating ventilation rather than acting as a barrier during mouth-to-mouth resuscitation or rescue breathing scenarios.