[BennyB]

Keep in mind that CPR is Cardio Pulmonary Resuscitation, which is the chest compressions. EAR is Expired Air Resuscitation which is mouth to mouth. What do you mean by BTT? I haven't heard this term before.

Interesting point you raise Henjon about flowing air into the stomach instead of the lungs. We were always taught in the life saving club when I was a teenager to tilt the head back fully when giving mouth to mouth otherwise the air goes straight into the stomach. This can be a bit hard if you're in the pool or open ocean and you're having trouble balancing. We were taught Mouth to Nose as well, which sounds gross but is a bit easier to maintain a head tilt if you haven't got your balance because you're in deeper water.

I think it's entirely possible for somebody to BO or Samba after short distances/times underwater. Think if somebody tried to sprint 25m no-fins or did back to back laps without a proper rest in-between. A guy I used to train with had another dive buddy that would nearly always BO at 48m no-fins, yet this guy was athletic and could easily do a 4+min static.

Cheers,
Ben