1) Call 911
2) Push hard and fast in the center of the chest
That's it.
I'm working with the American Heart Association to help raise awareness of this simple yet highly effective life-saving technique known as Hands-Only CPR. They've created a website up with instructional videos, FAQs and "Hand Symphony," an interactive game demonstrating the power of hands.
So, let's try that again: would you know what to do if someone dear to you suddenly collapsed?