Of course you don't want to plan to have a medical emergency while trapped in a flimsy aluminum tube 35,000 feet in the air flying through bitterly cold air! But you do want to plan for a medical emergency -- just in case. The best way to prepare is to know what could happen. These are dangerous (and not-so-dangerous) medical conditions that can strike equally in coach or first-class.
There is no worse emergency than when the heart stops. It's a bummer when this happens anywhere, but sitting on an airplane has got to rank as the worst. With any luck, your neighbor in the aisle seat checking his Blackberry 15 minutes after the flight attendant told him to turn it off is familiar with doing CPR. Either that, or he hopefully will look away from the text messages just long enough to notice you've ominously stopped snoring. A quick wave to the cabin crew should summon at least one CPR certified helper -- complete with an AED.
Having a heart attack is almost as bad as having your heart stop. You really shouldn't have chest pain while flying unless you're the one flapping your wings. This might be important enough to get the pilot to put down in a closer airport -- especially if you're suddenly breaking a sweat.
Usually when I drool on an airplane, it's because I can only afford to fly the red-eye. Suddenly drooling out one side of your mouth, especially if you can't feel your face (or your hand, or you're talking funny), then you might want to hit Blackberry guy and get him to throw something at the drink cart. This is another one of those emergencies that warrants a detour to the ground as soon as possible. Indeed, strokes have to be treated even faster than heart attacks.
Seizures look scary, but are not usually life-threatening. It matters if the seizure is new or if it has happened before. Seizures in people with seizure disorders are not much more remarkable than my daughter talking incessantly -- both are triggered in the brain and both are scary but relatively harmless. The danger comes from a seizure that lasts for a long time, like more than 10 minutes, or a string of seizures over and over again without ever letting the victim wake up.
We need sugar to live. I get more than my fair share, but for those with diabetes, keeping sugar levels from getting too high or too low is a constant struggle. If Blackberry guy is slurring his words and the only thing he's had to drink since you took off is coffee (especially if he wasn't slurring earlier), then you may want to ask him if he has diabetes.
I know you have to pay for your peanuts on most flights now, but if Blackberry guy buys a "snack pack" and you're allergic, the results are bound to be bad. Hopefully, you brought your Epi-pen with you. Of course, if you don't know what anaphylaxis or Epi-pens are, then you probably don't have it.
Do you really want Blackberry guy to deliver your next generation? I didn't think so. However, you probably don't want the cabin crew to deliver it either. Docs are OK -- paramedics are better -- but the best bet is to not fly after 34 weeks.
If your throat closes up, it's not a bad idea to get some oxygen. If your trouble breathing is from something identifiable, you may benefit from some medication. The medical kit on the plane is stocked with some pretty advanced drugs. The cabin crew can't use those extra meds (they're not trained for that).
Sometimes, your trouble breathing is not related to a medical cause, but to have shortness of breath and not be able to fix it -- since it's not medical in nature -- can cause stress and anxiety. Of course, stress and anxiety caused this in the first place.
It can get a little bumpy on the Seven-Something-Seven. If Blackberry Guy rips a gash on your forehead with his mobile (that he should've turned off hours ago), you'll have to hit the bathroom for a quick field dressing. Use the stuff in the airline first aid kits -- you've earned it.