You've captured the whole experience so poignantly it is as though I'm there. The use of short run-on stanzas works well to convey the moment to moment feeling. They also come like bursts of fire to keep the reader from getting complacent.
You've deliberately (I assume) left the purpose of the vigil unexplained but you end with the type of resolution that indicates the diagnosis was unfavorable yet ameliorable.
As a friend, beyond the curiosity of the reader, I want to know the back story.