Cystic Fibrosis
A genetic disease causing thick, sticky mucus buildup in the lungs and digestive tract, leading to life-threatening respiratory infections and malnutrition.
Emergency Management: Massive hemoptysis requires ICU admission, correction of coagulopathy (Vitamin K), stopping airway clearance techniques, right lateral decubitus positioning (if bleeding from right lung), and urgent interventional radiology consultation for embolization.
Cystic fibrosis (CF) is an autosomal recessive genetic disorder caused by mutations in the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) gene. It is characterized by the production of thick, viscous secretions in various exocrine glands, primarily leading to progressive obstructive lung disease, pancreatic exocrine insufficiency, and elevated sweat chloride concentrations.
Detailed Overview
Defective CFTR function results in impaired chloride and bicarbonate transport across epithelial surfaces. In the lungs, this dehydrates airway surface liquid, crippling mucociliary clearance and creating a nidus for chronic bacterial infections (notably Pseudomonas aeruginosa) and severe neutrophilic inflammation. This vicious cycle inexorably leads to bronchiectasis and respiratory failure. In the pancreas, thick secretions obstruct ducts, leading to autolysis and exocrine insufficiency. The advent of highly effective CFTR modulator therapies has transformed CF from a fatal childhood illness into a manageable chronic disease extending into adulthood.
Epidemiology & Demographics
Incidence is 1 in 3,000 live births in the Caucasian population. Prevalence in the US is approximately 35,000 cases. The median predicted survival age has improved dramatically to >50 years.
Etiological Mechanism
Autosomal recessive inheritance. The most common mutation is the F508del mutation on chromosome 7, which causes abnormal protein folding and premature degradation of the CFTR channel before it reaches the cell surface.
Primary Causes
Inheritance of two mutated copies of the CFTR gene
The CFTR protein is an ATP-gated anion channel responsible for transporting chloride and bicarbonate. In normal airways, CFTR secretes chloride into the lumen, drawing water with it to maintain the airway surface liquid (ASL) layer required for ciliary function. In CF, absent or dysfunctional CFTR prevents chloride secretion, and hyperactivates the ENaC channel (which absorbs sodium). This causes massive reabsorption of sodium and water into the cell, severely dehydrating the ASL. The mucus becomes highly viscoelastic and cannot be cleared. This static mucus acts as a biofilm for pathogens (S. aureus, P. aeruginosa). The resulting chronic infection recruits massive numbers of neutrophils, releasing elastase and proteases that destroy the airway architecture, causing bronchiectasis. Similar pathophysiology in the pancreas obstructs exocrine ducts, leading to malabsorption of fats and fat-soluble vitamins.
Diagnostic Criteria & Guidelines
Diagnosis requires: 1) Clinical symptoms OR positive newborn screen OR sibling with CF, PLUS 2) Evidence of CFTR dysfunction: Elevated sweat chloride ≥ 60 mmol/L on two occasions, OR identification of two disease-causing CFTR mutations.
Airway Clearance Therapy: Daily use of vibrating vest (HFCWO), Nebulized Dornase alfa (rhDNase) 2.5 mg daily, and Inhaled Hypertonic Saline (7%) BID to thin mucus. Infection Control: Inhaled Tobramycin or Aztreonam alternated monthly for chronic Pseudomonas. Nutrition: Pancreatic Enzyme Replacement Therapy (PERT) with every meal/snack (e.g., Creon) and fat-soluble vitamin (A, D, E, K) supplementation. CFTR Modulators: Elexacaftor/Tezacaftor/Ivacaftor (Trikafta) daily for patients ≥2 years old with at least one F508del mutation.
Second-Line & Adjunctive Therapy
For acute pulmonary exacerbations: 14-21 days of dual IV antipseudomonal antibiotics (e.g., Cefepime + Tobramycin) combined with aggressive airway clearance. Treatment of CFRD requires insulin (oral hypoglycemics are ineffective).
Surgical & Procedural Management
Bilateral lung transplantation for end-stage lung disease (FEV1 <30%, severe hypoxemia). Bronchial artery embolization for massive hemoptysis.
Patient Counseling & Advice
Emphasize that survival requires absolute dedication to daily time-consuming therapies (often 2-3 hours per day of nebulizers and chest physical therapy). Counsel families on the importance of aggressive nutritional support. Explain that while highly effective modulators exist, they are not a cure and chronic therapies must continue.
Follow-Up & Monitoring Schedule
Quarterly visits to a specialized CF center. Routine spirometry, sputum cultures, weight/BMI tracking, and annual OGTT to screen for CFRD starting at age 10.
Preventive Strategies
Prenatal carrier screening for high-risk populations. Newborn screening (measuring immunoreactive trypsinogen [IRT]) enables early diagnosis and nutritional intervention before failure to thrive occurs.
Prognosis has radically improved. Babies born today with CF have an expected median survival well into their 50s or beyond, largely driven by Trikafta and comprehensive multidisciplinary care.