If you've been trained in CPR, the choice is obvious: Ask someone to call for help and find an AED, if possible, and then immediately begin chest compressions. The problem, according to Joni Nowak, RN/CCRN and owner of Lakewood Learning Center, is that many people who are not trained in CPR will simply stand by and wait for emergency services to arrive – therefore losing critical time instead of delivering life-saving compressions.

I recently took CPR and AED training through the American Heart Association's HeartSaver CPR/AED course, which I followed by completing a skill-testing session with Nowak. Here are five facts about AEDs and CPR that I learned during my training:

1. CPR will not restart a heart. Instead, it manually pumps blood through the heart and enables oxygen to reach the brain. This is absolutely vital for someone experiencing cardiac arrest. According to the America Heart Association, if CPR is administered immediately, it doubles or even triples the victim's rate of survival.

2. CPR is hard work. Pushing hard on the victim's chest (at a depth of about 2 inches) at a rate of 100 compressions per minute can quickly become exhausting. If another person is available to help give CPR, you should switch out every 2 minutes.

3. Both CPR and AEDs are safe. Nowak stresses that it's unlikely you'll hurt someone by performing CPR. And because CPR is so critical in the first minutes someone experiences cardiac arrest, you should administer this life-saving action even if you're not absolutely sure whether the victim is breathing or has a heartbeat. Good Samaritan laws also should protect you even if an unlikely injury does occur.

4.An AED will administer a shock for two types of abnormal heart rhythms: ventricular tachycardia and ventricular fibrillation. These are fatal arrhythmias, Nowak explains. While they have a high likelihood of being corrected by an AED, they also may recur, which is why it's important to leave an AED on (while continuing to administer CPR) until emergencies services arrive.

5. AEDs are so easy a third-grader can use one – literally. According to Nowak, when third graders were presented with AEDs and asked to use them, they were able to do so correctly. An AED will talk you through each step and determine whether or not a shock is needed. It's that easy.

I took this training for my upcoming Break Room column, "In a Heartbeat." Be sure to look for it in the April 2012 issue of EHS Today.