Hi, Toby. Good news! Moving forward -
If you think this might be a problem again, do follow Steve's advice and check into travel insurance - make sure to read about pre-existing conditions, and what the rules are and purchase your travel accordingly.
Re Airlines: Best piece of advice I can offer - Buy your airline ticket from a US airline, on a US site, and make sure it's ticketed by a US airline. Five huge advantages for this situation:
One - Your dealing with US law and customer service attitudes, which is a little easier for us, and broadly speaking usually a bit more customer friendly.
Two - If you do get a non-refundable but changeable ticket (the vast majority of tickets out there), you can use it to fly anywhere that US airline goes! Aka - You'll have a lot more options on Delta or NW out of MN than you would with Iberia.
Three - The US govt (Dept of Transportation) makes all airlines post their contracts of carriage in easily readable places - aka you can find the rules a little easier.
Four - Most US airlines DO have policies regarding refunds or lowered change fees for medical reasons. This is pretty standard practice. You generally have to provide a note from your doctor that you cannot fly. Policies vary from airline to airline but generally involve A) Refund, or B) Lowered Fees.
Five - If you think it's tough getting a refund from a US airline.. try getting one from Al Italia. I've even seen people with approved refunds never get them or get them literally years after the fact.
Contrary to the statements above, you can purchase these changeable and "Y" class tickets (class of service) on Expedia, etc. Expedia even has a check box that says, "Avoid most change penalties".
PS - Most 1st class tickets are completely refundable and changeable.
Hope that helps! Give me a shout with any questions.