I usually finish that with "I can't do anything for you". The weight limit is actually somewhat higher, but not much more than double unless you need an IV. I do know CPR, and I hope I'd remember how to do chest compressions with more than my thumbs should the need arise.
Years ago, when I was a fairly new nurse, I took a friend to the airport on a very hot summer day. We went to an extended parking lot and walked toward the bus which we planned to ride to the airport. As we rounded the back of the bus, we spotted the bus driver with her head on the concrete and her feet on the bottom step of the bus. I stood there with my mouth open until my friend slugged my shoulder and said, "You're a nurse, do something."
I sprung into action and determined that the bus driver was breathing and pink and, since we couldn't tell whether there were serious injuries, we shouldn't move her. Then I turned to my friend and said, "There's a radio on that bus. You're an engineer - your turn." Fortunately, the bus driver regained consciousness at that point and was able to call for assistance herself.
As I was telling this story to a friend recently, she glanced out the window of the restaurant where we were dining and noted the presence of an ambulance, commenting that she'd seen several others that day. Moments later, a contingent from the local EMS entered the restaurant and approached a nearby table where a patron was slumped over.
Yep. If you weigh more than 10 pounds, you might want to find a nurse with some actual adult experience if you're not feeling well. I can call 911 as fast as anyone, but I don't promise to notice that you're not actually napping when your eyes are closed.