Update

Dad's back home; he slept well last night and seems OK, apart from some pain - muscular, I presume - in the chest area. O sent me a picture of him in the hospital, and yeah, it looks pretty bad - an enormous black eye. (She says it looks even worse now.) But it seems that he's gotten through the episode without serious damage. Poor guy. Thanks to all of you who offered support; I - we - appreciate it.