The structure of the lung allows rapid uptake of oxygen from the air and diffusion into the bloodstream. Air is warmed and moistened in the mouth and nose, which makes it less irritating to the airways, while nose hairs trap particles such as dust, pollen, and bacteria. The filtered air then moves through branching airways that are lined with mucus to collect any particles that get through. The air travels through smaller and smaller airway branches until reaching tiny air sacs called alveoli, where oxygen and carbon dioxide are exchanged.
In CF, faulty transport of electrolytes across airway tissues leads to abnormal mucus production along the respiratory tract. This mucus is easily dehydrated and difficult to clear. Eventually, the mucus obstructs the airway, impairing the alveoli, and prevents foreign particles from being cleared, resulting in chronic lung infections.
Chronic Lung Disease
CF airways are obstructed by thick mucus that make it difficult to clear infection-causing bacteria like Pseudomonas aeruginosa, Staphylococcus aureus, Hemophilus influenzae and Burkholderia cepacia. Over time, these bacteria cause a chronic infections leading to inflammation and damage to the airway walls and bronchiectasis, an abnormal stretching of the respiratory passages.
Several tests determine the extent of infection, inflammation, bronchiectasis and mucus plugging in the lungs. Spirometry, for example, measures a patient’s respiratory cycle as he or she breathes in and out of a mouthpiece. Changes in the rate of airflow will detect development, progression, and response to therapy. More extensive pulmonary imaging procedures such as chest X-rays and chest CT scans are also used to determine the extent of CF lung disease.
CF is characterized by recurrent pulmonary problems like shortness of breath, increased cough and sputum production, fatigue and occasionally hemoptysis, or coughing up of blood. Exacerbations are caused by bacterial or viral infections in the bronchi and bronchioles leading to inflammation. Some pulmonary exacerbations can be treated at home with antibiotics, aggressive chest physiotherapy, and breathing treatments. If symptoms persist or worsen, hospitalization will likely be necessary for intravenous antibiotics and other interventions
Hemoptysis, or coughing up blood, is a common CF complication. The condition varies from streaks of blood in mucus to mouthfuls of blood that are coughed up from hemorrhage in the airway. Infection and inflammation change the pulmonary blood vessels, erode the airway blood vessel walls, dilate the bronchial arteries, and form abnormal connections between bronchial and pulmonary arteries that bleed easily. Infections increase the risk of hemoptysis, but they can be treated with antibiotics. Minor hemoptysis is common, occurring in up to 75 percent of adults with CF. Major hemoptysis, defined as more than 200 milliliters of blood (about the volume of a can of soda), occurs much less frequently, but requires immediate attention. Medications, such as aspirin, that affect the ability of the blood to clot should be avoided
Pneumothorax, a potential life-threatening complication of CF, literally means air in the chest, but refers specifically to air surrounding the lungs. Normally, this space contains a small amount of fluid. When air is in this space because of rupture of alveoli or trauma, the surrounding lung tissue may collapse. Pneumothorax occurs in approximately 4% percent of people with CF each year and 50 percent of these patients will have more than one occurrence. Symptoms include sudden chest pain and shortness of breath. Smaller pneumothoraces may not cause symptoms and tend to resolve themselves. Diagnosis is usually confirmed by a chest X-ray. A small pneumothorax may be managed with supplemental oxygen and monitoring, but a larger pneumothorax is treated with a chest tube to remove the air.