What do you do if a co-worker suffers from cardiac arrest at work?

CPR: If a person collapses, check for their pulse and if absent call 911 and perform cpr; basically, perform chest compression at a rate of 100 per minute, pushing with both hands interlocked on the breastbone, trying to 'push it in' about an inch. Don't stop until paramedics arrive.

CPR, shock: Call 911, then use CPR and (if you have one) place the pads for the office AED on him/her and follow directions. Dont stop until relieved by ems.