What should be done if a guest begins to vomit during rescue breathing?

When a guest begins to vomit during rescue breathing, the most appropriate action is to turn the guest onto their side. This maneuver is crucial as it helps prevent the vomit from obstructing the airway, which is essential for ensuring that the individual can breathe properly. If the person is lying flat on their back, the vomit can easily block the airway, leading to further complications. By positioning the guest on their side, any vomit can drain out of the mouth, reducing the risk of aspiration, which can cause choking or complications in the lungs.

This action also allows the rescuer to maintain an effective airway management strategy while ensuring safety during the resuscitation process. It's important to prioritize the airway and prevent any obstructions to maximize the chances of a successful resuscitation.