Borrowed from a CPR instructors group on Google Groups that I belong to:
If I want a beer and I pump the keg 5 times and pour 1 lousy beer, the pressure drops back down (G1992)
If you and I team up and pump the keg 15 times and pour 2 OK beers, pressure still drops (G2000)
If we team up and pump the keg 30 times we get 2 really good beers (G2005)
If we pump the keg 50 or 100 times it kills us before we get a beer (50:1 & 100:1 studies)
This ends our beer keg to heart anatomy and physiology lesson for today.
Interesting analogy on the progression of compressions to ventilation ratios.