Cystic fibrosis

Background

• Autosomal recessive genetic disorder
  • Due to a mutation in cystic fibrosis transmembrane conductance regulator protein (CTFR)
  • CTFR=chloride channel important in function of mucus, sweat, and digestive fluids.
• Causes thick, viscous mucus leading to obstruction and damage to exocrine organs

most common problem that these patients have are diseases related to the lung (pneumonia, bronchiectasis) and GI tract (pancreatitis).

Clinical Features

• Disease manifests primarily in lung and GI tract
• Pulmonary/upper respiratory
  • Acute exacerbations lead to increase in baseline cough and sputum production
  • Pneumonia
    • Chronic infection with multiple organisms
    • Staph aureus and H. influenzae common in childhood
    • Most eventually chronically infected with pseudomonas aeruginosa and/or virulent gram-negative
    • Pseudomonas features include: severe pneumonia, cyanosis, confusion, often bilateral, occasionally empyema
    • Higher risk for aspergillosis
  • Increased risk of pneumothorax (8%–20% will develop one in lifetime)
  • Bronchitis
  • Sinusitis, nasal polyps
  • Chronic inflamation/infection leads to bronchiectasis and angiogenesis, which may lead to hemoptysis
  • Long-standing disease can eventually lead to cor pulmonale
• Gastrointestinal
  • Pancreatic insufficiency
  • Pancreatitis
  • Diarrhea and malnutrition due to resultant malabsorption
  • Meconium ileus: failure to pass meconium within first 48 hours of life
    • Obstruction due to thick meconium
    • Can lead to perforation if unrecognized
• Other
  • Electrolyte disturbances
    • Chloride wasting, diarrhea can lead to hypokalemic, hypochloremic metabolic alkalosis
  • Suppurative parotitis
    • Rapid onset parotitis (warm, swollen, tender gland, fever, trismus)
    • Purulent drainage from Stensen's duct
    • Organisms: staph, strep pneumo, strep pyogenes, H. flu, e. coli, pseudomonas

Evaluation

Initial diagnosis of cystic fibrosis is with sweat test and/or genetic tests

• CBC (signs of infection), electrolytes, LFTs/lipase if concern for pancreatitis
• Consider blood and sputum cultures (may have resistant organisms)
• CXR
  • Advanced disease: peribronchial thickening, mucous plugs, cystic/bullous lesions, atelectasis, hilar adenopathy, air trapping
  • Infiltrates if pneumonia
  • Pneumothorax

Management

• Infections
  • Many patients already on maintenance azithromycin or tobramycin
  • Antibiotics for acute pneumonia must be broad and include pseudomonal coverage
    • e.g. Cefipime, Imipenem OR Piperacillin/Tazobactam + IV fluoroquinolone, +/- vancomycin for MRSA
• Other respiratory adjuncts
  • Albuterol or other short-acting Beta-2 agonist
  • Dornase alfa (inhaled recombinant deoxyribonuclease I, hydrolizes DNA in sputum to decrease viscosity)
  • Nebulized Hypertonic saline (reduce sputum viscosity)
  • Inhaled nitric oxide
  • Chest physical therapy
• See treatment for pancreatitis
• Rehydrate if volume depleted, replete electrolytes
• Note potential for hypoalbuminemia when giving extensively protein-bound drugs

Disposition

• Dispo decision should be made in conjunction with patient's pulmonologist if possible, as they often know their patients very well

See Also

• Pneumonia
• Pseudomonas
• Diarrhea
• Metabolic alkalosis