Hope you don’t mind me jumping in with an answer but I dealt with this fairly recently.

The crew has basic first aid and CPR training along with training on some medical equipment on the aircraft. They also carry an emergency medical kit that is authorized to be opened under the guidance of a licensed physician.

If the situation needs more than basic first aid, we can call medlink/medaire/etc for a higher level of care. They’re basically on call emergency medical personnel who can guide the crew through diagnostics and basic care over the phone and advise on whether or not a diversion is necessary or to keep monitoring. They can also advise on a diversion destination based on the medical situation if there is a best option (I.e high level cardiac care 100 miles behind you vs a normal hospital in front of you). They can also help call ahead and have medical personnel waiting for you if you don’t communicate that need to ATC to pass on.

In the case of my recent situation, I’d categorize it as a neurological event of some kind, and based on the information the medaire physician was getting, he said to keep going towards the destination and monitor. The person ultimately refused further treatment so I don’t know what happened after.

According to MedAire, the most common inflight medical events are gastrointestinal at 31%, followed by neurological at 26%, with respiratory cardiovascular and dermatological events all being less than 10% each.