You are called to a home where a family has been enjoying a Labor Day picnic and swim party. A 2-year-boy slipped to the bottom of the pool unnoticed. By the time you arrive, the child has been removed from the water and family members are administering CPR. You assess the child and note that he has a weak pulse and is trying to breathe on his own. You initiate transport and continue providing positive pressure ventilations. You are also very concerned about: