Maybe it would help if you think of this patient as someone close to you a parent or grandparent.
What comes to mind why an 80yr.old with asthma might be in the ED in respiratory distress?
For me I would think knowledge deficient, poor health maintenance, or memory impaired, does he know what to avoid that triggers his asthma, does he recognize early signs of an asthma attack, what medication is he on and does he know what to use when, does he know how and when to use his rescue inhaler.
risk for Ineffective Airway clearance r/t tracheobronchial narrowing, as "Karolyte" stated above.
risk for Ineffective Health Maintenance r/t deficient knowledge regarding physical triggers, medications, or treatment of early warning signs.
risk for Ineffective Therapeutic Regimen Management
When I was in nursing school often I felt stumped too when the instructor asked questions. In hindsight, I felt I needed to give a very intellectual sounding answer or a word for word Nanda nursing diagnosis. Now, honestly, I think if I had said risk of his airway constricting, or risk of future asthma attacks, something that would have told my instructor I understood this patient's "priority diagnosis" would involve the "A" of ABC's Airway, Breathing, and Circulation I would have been fine with those answers. I quess it all depends on how strict your instructor is.
For the Schizophrenic patient
disturbed, Thought Processes, is the first thing that comes to mind but for your patient who had been fighting I would prioritize Violence or Injury.
risk for self- and other-directed Violence r/t lack of trust, panic, hallucinations, delusional thinking
risk for injury
These are some other possible nursing diagnosis for schizophrenia but not ones that I could spout off in post conference without having looked at a list of nursing diagnosis ahead of time.
Social interaction impaired
risk for, relocation stress syndrome
disturbed personal identity
ineffective community coping
Best of Luck