Chapter 22: Cystic Fibrosis

Question 1

Etiology of Cystic Fibrosis

Answer 1

• autosomal reccessive disorder of exocrine glands
• most common genetic lung disease in the US
• classified as airflow or suppurative (pus-forming)
• hypersecretion of abnormal, thick mucus that obstructs exocrine glands and ducts
• median survival age is about 31 years

Question 2

Pathogenisis of cystic fibrosis

Answer 2

• Dysfunction of CFTR gene
• Primarily affects the pancreas, intestinal tract, sweat glands, and lungs, and in males causes infertility
• high concentrations of sodium and chloride in sweat, salivary, and lacrimal secretions (results in salty skin)
• mucus producing glands in the GI tract enlarge
• bronchopulmonary system is also affected by the thick, tenacious mucus

Question 3

Pathogenesis of Cysitic Fibrosis (dysfunction of CFTR gene)

Answer 3

• normally CFTR encodes a membrane chloride channel and is in sweat glands, lungs, and pancreas
• CFTR gene mutations result in alteration in chloride and water transport across epithelial cells

Question 4

Pathogenesis of Cysitic Fibrosis (mucus producing glands in GI tract enlarge)

Answer 4

• generates excessive secretions
• thick eosinophillic mucuous secretions plug the glands and ducts of the GI tract, causing dilation and fibrosis
• leads to decreased production of pancreatic enzymes, causing increased fat and protein in stool

Question 5

Pathogenesis of Cysitic Fibrosis (Bronchopulmonary system affected)

Answer 5

• failure of chloride channels to function
• decreased flow of ions and water results in viscid (thick) mucus
• causes airway obstruction, ateletasis (collapse of alveoli) and hyperinflation and also decreases cilliary action (bc mucus)
• Provides a medium for pulmonary infection (pseudomonas staph)

Question 6

Clinical Manifestations of Cystic Fibrosis (lung related)

Answer 6

• history of cough in young adult or child
• thick, tenacious sputum
• recurretn pulmonary infections and bronchitis
• Dyspnea, tachypnea
• Sternal retractions
• Unequal Breath sounds
• moist basilar crackles and rhonchi
• Barrel chest hyperresonant to percussion
• DIgital clubbing (late)

Question 7

Clinical manifestations of Cystic Fibrosis (other)

Answer 7

• pancreatic insufficiency
• cirrhosis of the liver
• diabetes mellitus
• gallstones
• nasal pollyps
• failure of development of the vas deferens in males
• Nutrional assesment includes depleted fat stores, Steatorrhea (fatty stools), anorexia, and decreased growth rate in children

Question 8

Diagnosis of Cystic Fibrosis

Answer 8

• ABG (hypoxemia and hypercapnia (unable to breath enough to get rid of CO2))
• PFT ( Decreased VC, airflow, and TV; Increased airway resistance, functional residual capacity)
• Chest xray (patchy atelectasis, bronchiectasis, cystic lung fields)
• sputum culture and sensitivity
• 72 hr stool collection (fat absorption and secretion)
• Genetic testing (marker AF-508 confirms diagnosis)

Question 9

Treatment of Cystic Fibrosis

Answer 9

• aggressive treatment of respiratory infections
• postural drainage and chest physiotherapy (chest percussion)
• Forced expiratory technique

Question 10

Medicinal Treatment of Cystic FIbrosis

Answer 10

• Bronchodilators
• Recombinant human deoxyribonuclease 1 (dornase alfa): digest extracellular DNA present in the viscid sputum
• High dose antibiotics
• Influenza Vaccine

Question 11

Nutritional Therapy for Cystic Fibrosis

Answer 11

• unrestricted fat consumption; 30% of caloric intake
• high protein
• vitamin supplements, esp A, K, D, & E
• Pancreatic Enzymes
• Intake of 150% of normal caloric intake
• May need enteral feedings or IV (through tube)
• may need heart or lung transplant