General Discussion

Mine was saline and antibiotics.

My guess is he gets regular infusions and has a 24/7 medical team attending him filling him with whatever will keep him healthy and alive. He could be dehydrated and receive saline if he consumes a lot of caffeine. They likely also want to make sure his blood doesn't thicken up like Nutella. There are probably rich people who get regular therapeutic IV cocktails of all kinds of vitamins and nutrients and other things civilians don't have access to. At his age, he's surely on a lot of meds and very few people would have the patience to sit and swallow 20-30 pills and vitamins at regular dosing intervals.

Having the IV in his hand means he doesn't have to remove a jacket to hook it up. They can also leave an IV needle inserted and taped up for several days if they know they're going to be blood-drawing or infusing him repeatedly.

I'd bet he has a permanently installed IV port that is like a metal button under the skin near the collarbone which accesses an artery. That's the normal spot they'd prefer to access an older person with delicate skin and difficult-to-access veins, but he's busy and having a tube in his neck isn't good for camera, so he prefers they put it in his hand.