May the Captain RIP. I'm sure the flight was safe with the first officer, but just imagine how it was for the crew? Serving drinks one minute and full blown emergency for the next 20 until the medics take over. The pilot must have had to been removed from the cockpit and layed out at the entrance for you do not have any space for CPR. Also, it's not easy to do CPR for over two cycles unless you have other trained people who can relieve you. Be trained in first aid and help when you can.