Cystic fibrosis and percentage of lung that still functions properly? how low does it need to be to qualify for a transplant?

Around 30 %: Many things about a patient and their cystic fibrosis (CF) are considered when a team is deciding whether or not to do a lung transplant. When lung function gets bad enough that the patient might die with a bad flare up or infection (often near 30%), they may be listed to get new lungs. It usually takes months to get new lungs, so teams want to use that time to improve strength and nutrition.