cystic Fibrosis

Cystic Fibrosis (CF) – Notes

Etiology

  • Most common fatal inherited disease in children

  • Autosomal recessive genetic disorder

  • Many possible mutations; most cause abnormal Na⁺/Cl⁻ transport across epithelial cells

  • Results in thick, sticky mucus in:

    • Airways → obstruction, infections

    • GI system → blocked pancreatic/liver ducts → ↓ protein & fat digestion → malnutrition

    • Deficiencies of fat-soluble vitamins (A, D, E, K)

    • Steatorrhea (fatty stools), diarrhea

    • Meconium ileus in newborns

    • Sweat glands: salty sweat

Anatomic Alterations

  • Bronchial gland hypertrophy & goblet cell metaplasia

  • Dehydrated airway surface → ↓ mucociliary clearance

  • Frequent infections (esp. Staph aureus, H. flu, Pseudomonas)

  • Airway obstruction → air trapping, atelectasis, bronchiectasis

  • Overdistention of alveoli

Restrictive & Obstructive Characteristics

  • Obstructive: mucus plugging, air trapping

  • Restrictive: from atelectasis, scarring, or advanced bronchiectasis

Screening & Diagnosis

  • Indications: “My baby tastes salty,” newborn screening

  • Pulmonary signs: chronic cough, sputum, recurrent infections

  • GI signs: failure to thrive, greasy/foul-smelling stools, vitamin deficiency

  • Other: meconium ileus (newborns), male infertility (adults)

  • Gold Standard: Sweat chloride test

    • Pilocarpine + electric current

    • Cl⁻ > 60 mEq/L = diagnostic

Clinical Appearance

  • May appear normal when stable

  • Exacerbation:

    • ↓ compliance

    • Moderate–severe hypoxemia

    • ↑ airway resistance

    • Accessory muscle use, pursed-lip breathing

Chest Exam & Imaging

  • Variable findings (depends on pneumonia, atelectasis, or air-trapping)

  • Diminished breath sounds

  • Bronchial sounds, crackles & wheezes

  • CXR: signs of atelectasis, pneumonia, bronchiectasis

Associated Pathology

  • Cor pulmonale → right heart failure (JVD, edema)

  • Polycythemia (from chronic hypoxemia)

  • Pneumothorax (spontaneous or with PPV)

PFTs & ABGs

  • PFTs: primarily obstructive, restrictive changes possible with severe disease

  • ABGs:

    • Early: respiratory alkalosis + hypoxemia

    • Chronic: ventilatory failure

    • Exacerbations: acute hypoventilation/hyperventilation on chronic failure

Treatment & Patient Education

  • Airway clearance (daily self-care is key):

    • CPT (chest physiotherapy)

    • HFCWO (Vest therapy)

    • PEP devices, autogenic drainage

  • Medications:

    • Bronchodilators (albuterol, ipratropium)

    • Dornase alfa (Pulmozyme) – mucus thinning

    • Hypertonic saline (possible)

    • TOBI (tobramycin inhalation) for Pseudomonas

  • Prevention:

    • Avoid infection exposure

    • Early recognition and aggressive treatment of infections