NCLEX Review Guide: Cystic Fibrosis in Pediatrics

Genetic Basis

• Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations in the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) gene located on chromosome 7. The most common mutation is ΔF508, which accounts for approximately 70% of CF cases in North America.
• Both parents must be carriers of the defective gene for a child to inherit CF. Each child of carrier parents has a 25% chance of having CF, a 50% chance of being a carrier, and a 25% chance of being neither affected nor a carrier.

CFTR Dysfunction

• The CFTR protein normally functions as a chloride channel in cell membranes, regulating the movement of chloride ions and subsequently water across epithelial surfaces. When dysfunctional, it leads to thick, viscous secretions in multiple organ systems.
• Defective CFTR protein causes impaired chloride transport and increased sodium absorption, resulting in dehydrated secretions that obstruct ducts in the lungs, pancreas, liver, intestines, and reproductive tract.

Respiratory Manifestations

• Respiratory symptoms are the hallmark of CF and include persistent cough with thick sputum production, recurrent respiratory infections, wheezing, and progressive dyspnea. Airway obstruction leads to bronchiectasis, atelectasis, and eventually respiratory failure.
• Children with CF typically develop chronic colonization with specific pathogens including Pseudomonas aeruginosa, Staphylococcus aureus, and Burkholderia cepacia, which contribute to progressive lung damage and declining pulmonary function.

Gastrointestinal Manifestations

• Pancreatic insufficiency occurs in 85-90% of CF patients, leading to malabsorption of fats, proteins, and fat-soluble vitamins (A, D, E, K). This results in steatorrhea, failure to thrive, and nutritional deficiencies.
• Meconium ileus, a blockage of the intestines by thick meconium, is present in 10-20% of newborns with CF and may be the first clinical manifestation. Older children may develop distal intestinal obstruction syndrome (DIOS), characterized by partial or complete intestinal obstruction.
• Other GI manifestations include rectal prolapse, gastroesophageal reflux, and liver disease with potential progression to cirrhosis and portal hypertension in approximately 5-10% of patients.

Other System Manifestations

• Elevated sweat chloride is the hallmark diagnostic finding in CF, with concentrations typically exceeding 60 mEq/L due to defective chloride reabsorption in sweat ducts. This can lead to salt depletion, especially during hot weather or fever.
• Male infertility occurs in 95-98% of males with CF due to congenital bilateral absence of the vas deferens. Females may experience reduced fertility due to thick cervical mucus.
• CF-related diabetes (CFRD) develops in approximately 20% of adolescents and 40-50% of adults with CF due to progressive pancreatic damage affecting insulin-producing cells.

Diagnostic Criteria

• Diagnosis of CF requires either positive newborn screening followed by confirmatory testing or the presence of at least one characteristic clinical feature plus evidence of CFTR dysfunction (elevated sweat chloride, presence of two CF-causing mutations, or abnormal nasal potential difference).
• Newborn screening typically involves measurement of immunoreactive trypsinogen (IRT) from dried blood spots, with elevated levels triggering DNA analysis for common CFTR mutations. This allows for early intervention before significant organ damage occurs.

Diagnostic Tests

• The sweat chloride test remains the gold standard for CF diagnosis. Sweat is collected after pilocarpine iontophoresis stimulation, with chloride concentrations ≥60 mEq/L diagnostic of CF, 30-59 mEq/L intermediate, and <30 mEq/L normal.
• Additional diagnostic tests include pulmonary function tests (PFTs) showing obstructive pattern, chest X-ray revealing hyperinflation and bronchiectasis, sputum cultures identifying characteristic pathogens, and fecal elastase measuring pancreatic function.

Respiratory Management

• Airway clearance techniques are essential for mobilizing secretions and include chest physiotherapy, postural drainage, percussion, vibration, positive expiratory pressure devices, and high-frequency chest wall oscillation vests. These should be performed 2-4 times daily, especially before meals and bedtime.
• Inhaled medications include bronchodilators (albuterol), mucolytics (recombinant human DNase/Pulmozyme), and hypertonic saline to liquefy mucus. Inhaled antibiotics such as tobramycin, aztreonam, and colistin are used to manage chronic bacterial infections.

Chest Physiotherapy Procedure

1. Position the child appropriately for the lung segment being drained
2. Perform percussion with cupped hand over the chest wall for 3-5 minutes
3. Apply vibration during exhalation
4. Encourage deep breathing and effective coughing
5. Repeat for each affected lung segment

Nutritional Management

• Pancreatic enzyme replacement therapy (PERT) is essential for patients with pancreatic insufficiency. Dosing is based on weight and fat content of meals, typically 1,000-2,500 lipase units/kg/meal, not exceeding 10,000 lipase units/kg/day to prevent fibrosing colonopathy.
• High-calorie, high-protein diet with 120-150% of recommended daily caloric intake is necessary to compensate for increased energy expenditure and malabsorption. Fat-soluble vitamin supplements (A, D, E, K) are required, and salt supplementation may be needed, especially during hot weather or illness.

CFTR Modulator Therapy

• CFTR modulators are a revolutionary class of medications that target the underlying protein defect in CF. These include potentiators (ivacaftor/Kalydeco) that improve CFTR channel function, correctors (lumacaftor, tezacaftor, elexacaftor) that improve CFTR protein folding and trafficking, and combination therapies (Orkambi, Symdeko, Trikafta).
• Elexacaftor/tezacaftor/ivacaftor (Trikafta) is effective for patients with at least one F508del mutation (approximately 90% of CF patients) and has shown dramatic improvements in lung function, exacerbation rates, and quality of life. These medications are approved for various age groups, with newer options becoming available for younger children.

Respiratory Assessment and Interventions

• Perform comprehensive respiratory assessment including respiratory rate, effort, breath sounds, oxygen saturation, and sputum characteristics. Monitor for signs of respiratory distress or infection such as increased work of breathing, decreased oxygen saturation, fever, or change in sputum color/consistency.
• Administer prescribed respiratory medications in the appropriate sequence: bronchodilators first, followed by airway clearance techniques, then mucolytics, and finally inhaled antibiotics. This maximizes medication effectiveness by ensuring optimal delivery to the airways.

Nutritional Support

• Ensure proper administration of pancreatic enzymes before meals and snacks. Capsules may be opened and sprinkled on applesauce for young children but should never be crushed or chewed as this destroys the enteric coating. For infants, beads can be mixed with a small amount of applesauce and administered before feeding.
• Monitor growth parameters (weight, height, BMI) at each visit and track on growth charts. A BMI ≥50th percentile for children 2-20 years and weight-for-length ≥50th percentile for children <2 years are the nutritional goals in CF care.

Psychosocial Support

• Provide age-appropriate education to the child and family about CF, its treatment, and self-management strategies. Encourage gradual transfer of responsibility for care from parents to the child as appropriate for developmental stage.
• Address psychosocial concerns including treatment burden, school issues, social isolation, depression, anxiety, and transition to adult care. Connect families with resources such as the Cystic Fibrosis Foundation, support groups, and financial assistance programs.

Acute Pulmonary Exacerbations

• Pulmonary exacerbations are characterized by increased cough, sputum production, respiratory rate, work of breathing, decreased exercise tolerance, decreased appetite, weight loss, and decreased pulmonary function. These require prompt intervention with intensified airway clearance and antibiotic therapy.
• Intravenous antibiotics are often necessary for severe exacerbations, typically with dual coverage targeting Pseudomonas aeruginosa (commonly an aminoglycoside plus an anti-pseudomonal beta-lactam). Treatment duration is typically 14-21 days.

Long-term Complications

• Hemoptysis can range from blood-streaked sputum to massive bleeding (>240 mL in 24 hours) requiring bronchial artery embolization. Management includes discontinuing NSAIDs, airway clearance modifications, antibiotics, and possibly vitamin K supplementation.
• Other complications include pneumothorax, allergic bronchopulmonary aspergillosis (ABPA), CF-related diabetes, bone disease (osteopenia/osteoporosis), and end-stage lung disease potentially requiring lung transplantation.

Preventive Measures

• Infection prevention through proper hand hygiene, equipment cleaning/disinfection, and avoiding exposure to individuals with respiratory infections is crucial. Annual influenza vaccination, pneumococcal vaccination, and COVID-19 vaccination are recommended.
• Regular exercise improves lung function, airway clearance, and overall health. Physical activity should be encouraged with appropriate hydration and salt replacement, especially in hot weather.

• Cystic fibrosis is an autosomal recessive disorder caused by mutations in the CFTR gene, resulting in thick, viscous secretions affecting multiple organ systems.
• Primary manifestations include chronic respiratory infections, pancreatic insufficiency with malabsorption, failure to thrive, and elevated sweat chloride.
• Diagnosis is confirmed through sweat chloride testing, genetic analysis, and clinical presentation, with newborn screening allowing early intervention.
• Treatment involves a multidisciplinary approach focusing on airway clearance, nutritional support, infection management, and CFTR modulator therapy when appropriate.
• Nursing care includes respiratory assessment and interventions, proper administration of medications and enzymes, nutritional monitoring, and psychosocial support.
• Complications include pulmonary exacerbations, hemoptysis, pneumothorax, CF-related diabetes, and progressive lung disease potentially requiring transplantation.

Common Misunderstandings

• Misconception: All CF patients have the same severity of disease.
  Correction: CF is highly variable in presentation and severity, depending on specific genetic mutations, age of diagnosis, adherence to therapy, and other modifying factors.
• Misconception: CF only affects the lungs.
  Correction: CF is a multisystem disorder affecting the respiratory, digestive, reproductive, and endocrine systems.
• Misconception: Pancreatic enzymes should be taken only with main meals.
  Correction: Pancreatic enzymes must be taken with all meals AND snacks containing fat or protein.

NCLEX Approach for CF Questions

• When answering NCLEX questions about CF, remember to prioritize airway clearance and respiratory status as these are most directly life-threatening. Apply the ABCs (Airway, Breathing, Circulation) framework to prioritize interventions.
• For medication questions, focus on proper administration sequence and timing: bronchodilators first, then airway clearance, mucolytics, and finally antibiotics. For pancreatic enzymes, remember they must be given before meals and snacks.

Critical Thinking Exercises

• Practice connecting CF pathophysiology to clinical manifestations. For example, how does CFTR dysfunction in the pancreatic ducts lead to malabsorption and nutritional deficiencies?
• When reviewing case studies, consider the whole patient, not just respiratory symptoms. Look for GI manifestations, nutritional status, and psychosocial aspects of care.

Self-Assessment Checklist

• I can explain the genetic basis and pathophysiology of CF
• I can identify the major clinical manifestations of CF across body systems
• I can describe the diagnostic criteria and tests for CF
• I can outline the comprehensive management approach for CF
• I understand proper administration of medications and treatments
• I can recognize signs of pulmonary exacerbation requiring intervention
• I can explain the psychosocial impact of CF and appropriate nursing support