How can I help my father with is critical asthma?

Engage with provider. It is useful for patients at any age to bring an advocate, whether a family member, friend or other to appointments. It would be helpful to review his medication, his environment, any difficulties that might make life more complicated (low vision, hearing). Ask for an action plan, in large writing, so that he can review with you after the appointment. FYI: asthma is usually not the only med issue.
Go with dad. to doctor and sit down and sketch out a plan of action. Make sure your father is using his asthma medications and pumps correctly. Bring a bag of all of his medications and supplements, herbal pills ect to show the doctor what he is taking. Review in detail why and how each medicine should be taken. Make sure your dad lives and breathes clean air. (remove environmental irritants and allergens)