Thanks for asking the query,
As you have mentioned you have bad breath due to COPD i would suggest you to consult the Physician and discuss the problem.
Visit the Dentist
and go for professional scaling and polishing.
mouthwash gargles twice daily.
Maintain a good oral hygiene
Brush your teeth twice daily, clean the tongue gently with the help of tongue cleaner.
Drink plenty of fluids and keep yourself hydrated.
Hope this helps out.