Does he have active movement in the right hand?
If there is swelling, I would suggest elevating the hand and forearm (place on pillow) when seated and/or laying down in bed to help reduce edema (swelling). Try to elevate above heart level at an angle.
Swelling is common on the affected side. Our physiotherapist recommended placing my father's affected hand in icy cold water. It helps relieve the pain. Also, the swelling indicates that you need to exercise the affected hand more. Hope this helps:)
You should try to consult with an occupational therapist. Or go to an occupational therapy website to look for advice or examples of therapies for the arm.