Can't believe I missed this thread! Contrary to popular belief CPR has become very effective lately with the recent "first responder" changes. They're now teaching us to do two minutes of continuous "quality" compressions followed by two ventilations. We've really seen a huge jump in our "saves" here in Aurora. Make no mistake, if you're doing effective CPR you will break ribs & probably all of them. Ease up on compressions once they're broken. Depth is 2" on an adult. Switch out the person that's doing compressions every 4-6 minutes. Effective compression are very exhausting & the effectiveness drops off really quick!