"Also, ramming down on the abdomen is bound to cause injuries (the GI tract is a hollow organ, after all)."
I don't think they do it by ramming with fists or anything. If you looked at the site originally noted, you'll see a man holding a wooden panel with handles. I think they probably compress the whole area right under the diaphragm all at once.
Sue
That in itself is an issue, chest compressions (which have been proven to be effective WITHOUT ventilations for a period of time) requires no adjuct and any bystander can be instructed to do it by a 911 operator.