The old guidelines called for repeated shocks along with a pulse check before administering CPR. The new way endorses a single shock followed by two minutes of CPR, the Heart Association said.In the EP lab where we witness cardiac arrest and all of its excitement first-hand, there is NO QUESTION that early defibrillation works. I have had times where one shock is not enough to resuscitate a patient in our lab setting. If I stopped to first perform CPR before shocking one of my patients during witnessed cardiac arrest, I am sure we would have a higher complication rate in our laboratory. Many of our patients have ischemic coronary disease, and when the heart fibrillates, no effective blood flow is pumped from the heart, cuasing it to be more susceptible to ventricular fibrillation, not less.
I suppose in patients who have collapsed for a while, there might be logic in the AHA's recommendations - circulate a bit of oxygenated blood to the heart first, then try shocking. But certainly in witnessed cardiac arrest, I'm going to shock them more than once every time.