I do not have the New England Journal article with me otherwise I would cite it. The reasoning behind the change is this.. your blood has residual oxygen in it that is sufficient to keep the brain alive as long as blood is being pumped to the brain. Giving rescue breaths does little to nothing in a pulseless patient unless the blood is being circulated to your brain. Also CPR is only a stop gap until definitive care can be administered. In most cardiac arrest cases, definitive care means defibrillation and anti arrythmetic drugs. CPR alone will generally not be sufficient in most cases to revive someone. I have not taken the scuba rescue course but I can say with some confidence that performing CPR in the water is an exercise in futility and that compressions will most likely be inadequate. As an aside, I am certified as a paramedic and in ACLS, as well as PALS so I am fairly up to date on medical protocols.