Not knowing what can make a difference seems useful only when combined with skillful presence.
When my Dad was in intensive care for a week. We were allowed to see him only twice a day for 5 mins each. My brother, in a stroke of genius, rented the hospital room right next to the intensive care room. So everytime we heard that door open for food service, cleaning service or doctors visit, me and my Mom would rush and wave our hands and my Dad started looking out for us and waving back. Initially we must have looked like clowns to the staff but we started waving at all the people in that room and even some staff would smile back or wave back. When Dad was shifted to palliative care, he mentioned this and smiled big. I had no idea it made a difference to him but it filled our hearts to connect so joyfully in a helpless and what seemed like a lonely situation.