Compressions keep the oxygen carrying blood circulating to the vital organs and these organs send the correct electrical signals to the heart to beat in a life sustaining sequence. Secondly, when the heart goes into a rhythm that does not allow the chambers to contract in the right sequence to pass the blood through, the rapid use of an AED sends a shock to the heart to assist in resetting it to a rhythm that can again sustain life.
Every. Second. COUNTS. Having quick access to an AED is crucial. We commonly hear in our classes that we have help around the corner so we can just start CPR and wait for an AED. Something everyone needs to think about is whether that help is really there? Commonly EMS and Rescue units are busy helping others. Your ambulance or rescue unit assigned to you could be coming from the other side of your city, or another township, or in extreme circumstances another county. For the average patient, an AED needs to be utilized within a 10-minute window. The patient on average loses a 10% chance of survival every minute that goes by without an AED placed in a cardiac arrest event. It is amazing how many minutes are lost just calling 911, having the emergency units get out the door, and the time it takes to drive to your location. 
The more people that are trained in CPR/AEDs and the more AED units there are installed within a community, the bigger the impact on public safety. Let's get these units in every business and public access point that we can.