For serious medical emergencies when a patient can't walk or be carried out, a helicopter rescue can be arranged through the Royal Nepalese Army or by a private company. The service is expensive and must be paid for by the rescue. Your embassy or trekking agency may vouch for you but they won't pick up the tab a good reason to arrange for comprehensive trip insurance beforehand.

The helicopter company's must receive assurance of payment before it dispatches a flight. This will be provided by your trekking agency if you're with a group; embassies usually provide this for their citizens, but they may need to contact the family in advance. Registering at your embassy be fore a trek greatly expedites this process. Once the helicopter takes off, you're liable for the costs even if it doesn't find you.