I was always taught that giving someone with a normal rhythym can send them into arrhythmia. Now AHA says that you shouldn't even check for a pulse, and should perform chest compressions even if there might be a pulse. Their reasoning behind it seems to have nothing to do with the well-being on the patient:
"Why: The elimination of rescue breathing
without chest compressions will reduce the
number of CPR skills lay rescuers must
learn, remember, and perform. This change
also eliminates the need to further assess
the victim after the initial rescue breaths,
reducing the time delay before delivering the
first chest compressions."
Seems like just a couple of years ago they were talking about eliminating breaths altogether and just advocating chest compressions (contravening their old stance that compressions without breathing just circulates deoxygenated blood), but they changed their minds about that. I'll wager that this new thing of chest compressions on people with pulses will be reversed pretty soon here.