(1) You are not going to die.
Pros = The doctor should have reassured him to keep him calm
Cons = He could deteriorate rapidly and the doctor cannot guarantee if he could die or not.

(2) What makes you think that Chris?
Pros = Could reassure and calm Chris down and slow his breathing down as he is panicking
Cons = If he explain how he feels, this could take his increase his breathing and become breathless

(3) If you just slow your breathing down you will be fine.
Pros = This could help Chris calm down
Cons = Chris needs medical interventions to help his asthma attack so asking him to breathe slowing won’t help

(4) Everything will be ok, stop talking, to save your breath.
Pros = Reassuring Chris to calm him down and focus on his breathing
Cons = This is stopping him from communicating his needs