Cystic Fibrosis

Aka: Cystic Fibrosis, Mucoviscidosis, Fibrocystic disease of pancreas

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II. Epidemiology

  1. Usually diagnosed in childhood
  2. Incidence in live births
    1. Caucasian: 1:1500 to 1:2000
    2. Black: 1:17000
    3. Asian: 1:90000
  3. Carrier rate: 4-5% of Caucasian population

III. Pathophysiology

  1. Autosomal Recessive trait
  2. Exocrine gland disorder produces mucus blockage
    1. Blocks fine tubules in various organs

IV. Symptoms

  1. Respiratory
    1. Chronic Cough
      1. Productive of tenacious Sputum
    2. Wheezing
    3. Hemoptysis
    4. Dyspnea
  2. Gastrointestinal
    1. Voracious appetite
    2. Chronic Diarrhea
    3. Bulky malodorous stools
    4. Prolonged Neonatal Jaundice
    5. Unintentional Weight Loss
  3. Other
    1. Excessive sweating
    2. Positive Family History

V. Signs

  1. Digital Clubbing

VI. Complications

  1. Respiratory
    1. Recurrent Pneumonia
    2. Chronic Bronchitis
    3. Recurrent Sinusitis and pansinusitis
    4. Nasal Polyps
    5. Bronchiectasis
    6. Pseudomonas colonization of respiratory tract
    7. Pneumothorax
    8. Respiratory Failure
  2. Gastrointestinal
    1. Meconium ileus
    2. Fecal Impaction
    3. Intussusception
    4. Volvulus
    5. Distal Intestinal Obstruction Syndrome (DIOS, Meconium Ileus Equivalent)
      1. Small Bowel Obstruction in the ileocecal region
      2. Incidence: Occurs in up to 10 to 22% of Cystic Fibrosis patients
      3. Triggered by pancreatic insufficiency, dysmotility and Dehydration
      4. Presents with Right lower quadrant mass
      5. XRay demonstrates obstructive findings, but CT Abdomen is typically required
    6. Failure to Thrive
    7. Rectal Prolapse
  3. Other
    1. Cardiomegaly
    2. Diabetes Mellitus
    3. Metabolic abnormalities
      1. Hyponatremic Dehydration
      2. Chronic Metabolic Alkalosis
    4. Infertility in males (azoospermia)

VII. Labs

  1. Sweat Test
  2. Delta F508
  3. Agar Plate hand test
    1. White palmar implant from Sweat Chloride
  4. Starch tolerance test
    1. Pancreatic Insufficiency
  5. Electrolytes
    1. Sodium and chloride normal

VIII. Imaging

  1. Chest XRay
    1. Peribronchial cuffing
    2. Tram lines (Bronchial shadow lines)
    3. Fibrosis
    4. Recurrent infiltrates
    5. Pulmonary Blebs and bullae
  2. Abdominal XRay (KUB)
    1. Dilated loops of Small Bowel

IX. Management: CF Transmembrane Conductance Regulator (CFTR) Modulators

  1. Mechanism
    1. CF disease modifying agents
    2. Partially returns function of chloride channels, resulting in less mucus accumulation
  2. Preparations
    1. Trikafta (elexacaftor/tezacaftor/ivacaftor)
      1. Released in 2020, targets gene mutation found in 90% of CF patients (contrast with 50% for other agents)
    2. Kalydeco
    3. Orkambi
    4. Symdeko
  3. Dosing
    1. To maximize absorption, take with fat containing food such as peanut butter or avocado
    2. Also take with Pancreatic Enzymes (if already taking)
  4. Adverse Effects
    1. Expensive ($300,000 per year)
    2. Liver Function Test Abnormalities
  5. Drug Interactions
    1. Strong CYP3A4 Inducers
    2. Moderate to Strong CYP3A4 Inhibitors
  6. References
    1. (2020) presc lett 27(2):11

X. Management: Airway management

  1. Airway clearance
    1. Percussion and postural drainage
    2. Active cycle breathing
    3. Positive expiratory pressure mask
    4. Autogenic drainage
    5. Flutter valve
    6. Pneumatic vest
  2. Mucus thinning drugs
    1. Pulmozyme 2.5 mg nebulized qd
    2. Efficacy maintained for up to 1 year of treatment
    3. Reduces rate of respiratory infection
    4. Improves pulmonary function
  3. Antibiotics: Nebulized Tobramycin
    1. Traditional Tobramycin
      1. Dose: 80 mg/2cc nebulized TID
    2. TOBI
      1. Dose: 300 mg/5cc nebulized bid via Pari LC Plus
      2. Cost: $2000/28 day supply
  4. Antibiotics: Pneumonia
    1. Under age 10 years: Multiple organisms
    2. Age 10 and older: Pseudomonas predominates

XI. Management: Nutritional Supplements

  1. Daytime
    1. Scandibar 350 cals/bar
    2. Scandishake 600 cals/8 oz (with WCM)
    3. Calories Plus 450 cals/8 oz (with water)
    4. Carnation Instant Breakfast 290 Cals/8 oz
  2. Nighttime drip
    1. Tolerex 1.0 cal/cc
    2. Vital 1.0 cal/cc
    3. Peptamen 1.0 cal/cc
    4. Criticare 1.0 cal/cc

XII. Management: Other

  1. Growth Hormone
    1. Improved Growth Velocity improves pulmonary function
    2. Results in reduced hospitalization rates
    3. Hardin (2006) J Clin Endocrinol Metab 91:4925-9 [PubMed]
  2. Lung Transplantation
    1. See Lung Transplantation in Cystic Fibrosis
  3. Advanced Directives
    1. Discuss end of life issues as part of routine Health Maintenance

XIII. Management: Hospitalization Indications

  1. Increased cough
  2. Increased Sputum production or color change
  3. Anorexia and weight loss
  4. Exercise intolerance
  5. Malaise or irritability
  6. Decline in pulmonary function or CXR change

XIV. References

  1. Fuchs and Yamamoto (2011) APLS, Jones and Bartlett, Burlington, p.76-9
  2. Acherman (1998) PREP Course, Phoenix
  3. Wallace (1993) Clin Pharm 12:657-74 [PubMed]

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