Do I need accident insurance?
Yes.
Foreign hikers need check the terms of your insurance policy to ensure hiking is covered. We met hikers who were covered for climbing to 6000m but not for hiking!
Include also emergency evacuation service so you can catch the next flight home, if necessary.
In the mountains of Peru, be prepared to pay for your own medical care immediately. Insurance will likely need to repay you later.
Who administers First Aid?
In your hiking group, someone should be assigned the role of First Aider. This person must be confident, competent & certified in First Aid, preferably in the speciality of Wilderness First Aid. It's worth having someone in your group take a course before your hike.
Do not count on help from Peruvians you hire as guides.
If this is a problem, consider signing on with an expensive international tour company which should have trained, experienced first aiders. Check to be sure.
Who rescues me in case of emergency?
You are on your own.
The main worry is altitude sickness. Plan your escape route as you go just in case you are stricken.
The injured hiker should first try to reach a village linked by some kind of road:
Though you pay a high trekking fee to hike here, do not look for park rangers to rescue you. There closest authority to contact is likely at the Parque Nacional Huascaran office in the Llanganuco valley, 17km from Yungay.
On the other hand, Santa Cruz is a popular hike. Other hikers may assist you.
If the injured hiker cannot move, they should remain in a safe place. Don't leave them alone. Send other hikers to try to hire a horse to carry them out from another trekking group.
If hiring animals you might hire one horse to replace a burro) as the horse can be used for emergency evacuation. Burros only carry about 40kg.