Cystic Fibrosis Disease

BASICS

DESCRIPTION
Generalized, autosomal recessive disorder of infants, children and young adults with widespread dysfunction of the exocrine glands. Characteristics include chronic pulmonary disease, pancreatic insufficiency, abnormally high levels of electrolytes in the sweat, pansinusitis, digital clubbing and less frequently biliary cirrhosis, diabetes mellitus.
  • System(s) affected: Pulmonary, Gastrointestinal, Endocrine/Metabolic, Reproductive
  • Genetics: Autosomal recessive mutation of gene on chromosome 7. Linkage detection in families with known disease. Probes for direct detection available.
  • Incidence/Prevalence in USA: The most common lethal genetic disease. Caucasians: 1 in 2500 births, 1 in 17,000 African-Americans, and low in Native Americans and Asians.
  • Predominant age: Infants, children and young adults (oldest patient at time of diagnosis was 65)
  • Predominant sex: Male = Female
SIGNS AND SYMPTOMS
  • Sweat gland secretions:
    • Increased concentrations of sodium and chloride leading to hyponatremia, hypochloremia, arrhythmias
    • Dehydration with heat and infections
  • Respiratory:
    • Wheezing, chronic cough, dyspnea, barrel chest, tachypnea
    • Cyanosis, digital clubbing
    • Nasal polyposis, pansinusitis
    • Recurrent bronchitis and pneumonia leading to bronchiectasis
    • Predominant flora - Staphylococcus aureus and Pseudomonas aeruginosa. Burkholderia cepacia carries a poorer prognosis.
  • Gastrointestinal:
    • Failure to thrive
    • Meconium ileus
    • Distal intestinal obstruction syndrome (DIOS)
    • Colonic strictures possible with high-dose enzyme replacement (>15,000 U lipase /kg/day)
    • Chronic, recurrent abdominal pain
    • Gastroesophageal reflux
    • Voracious appetite prior to treatment
    • Abdominal distension
    • Hypoelectrolytemia and alkalosis
    • Characteristically frequent, bulky, foul - smelling, pale stool with a high fat content
    • Vitamin deficiencies (A,D,E,K)
    • Rectal prolapse
  • Others:
    • Delayed weight gain during growth and development
    • Retarded bone growth
    • Delayed sexual development
    • Males ~95% infertile
    • Decreased female fertility
CAUSES
Autosomal recessive genetic defect
RISK FACTORS
Positive family history (rarely seen due to recessive nature)

DIAGNOSIS

LABORATORY
  • Elevation of sodium and chloride concentrations in sweat (quantitative pilocarpine iontophoresis sweat test)
  • Genetic screening if sweat test inadequate (see Special Tests below)
  • Stool trypsin and chymotrypsin absent or diminished
  • 72 hour fecal fat excretion - increased fat in stool
  • Decreased albumin, fat soluble vitamins
  • CF gene screen (reference lab)
  • Mucoid Pseudomonas in respiratory secretions. Also S. aureus.

Drugs that may alter lab results: N/A
Disorders that may alter lab results:

  • Edema
  • Hypoproteinemia
  • Inadequate quantities of sweat to study
  • Adrenal insufficiency
PATHOLOGICAL FINDINGS
  • Lungs (major problem) - chronic inflammation, inspissated mucus, bronchiectasis with areas of fibrosis and atelectasis
  • Pancreas - obstructed ducts, acini replaced by fibrotic tissue, cysts, amorphous eosinophilic concretions and thick mucus
  • Liver - secretions obstruct biliary ducts; focal biliary cirrhosis
  • Intestine - hypertrophied mucous glands
  • Males - hypoplasia or atrophy of vas deferens
SPECIAL TESTS
  • Pulmonary function studies (2-3 times a year)
  • Sputum culture and sensitivity
  • Exercise testing
  • Response to bronchodilators - may show paradoxical drop
  • In newborns - serum concentration of immunoreactive trypsin reported to be elevated and used as a means of newborn screening. Radioimmunoassay developed for use with dried blood spots that are routinely collected for newborn metabolic screening.
  • Genetic testing to identify patient defect and analyze family for carrier status or prenatal diagnosis
  • Echocardiogram
IMAGING
Chest x-ray - hyperaeration, hilar adenopathy, occasional pneumothorax, bronchiectasis, blebs, increased involvement in right upper lobe
DIAGNOSTIC PROCEDURES
Diagnosis made in presence of clinical symptoms and positive sweat test, gene screen

TREATMENT

APPROPRIATE HEALTH CARE
  • Outpatient usually
  • Inpatient during infections or other crisis
  • Home care for IV antibiotics
GENERAL MEASURES
  • Care by experienced physician and team (respiratory therapist, nurse, nutritionist, physical therapist, counselor, social worker)
  • Goals are to prevent and treat respiratory failure and pulmonary complications
  • Postural drainage and chest physiotherapy - adjuncts include flutter valve and CPT vest (expensive)
  • Pancreatic enzyme replacement
  • Regular exercises for fitness
  • Press for adequate growth through good nutrition - supplements may be needed
  • Aerosol B2 agonists; consider ipratropium
  • Antibiotics - especially to target Pseudomonas, Staphylococcus
  • DNase: aerosolized mucolytic 2.5 mg neb q day. Use pari-plus nebulizer cup.
  • Oxygen: when needed
  • Monitor sleeping O2 stats
  • Barium enemas or surgery for unrelieved meconium ileus (newborn)
  • Barium enemas or surgery for unrelieved meconium ileus (newborn)
  • For fecal accumulation and intussusception in adults - enemas of diatrizoate sodium or Golytely per NG
  • Early identification of diabetes, and treatment with insulin
  • Assisted ventilation with BiPAP is acceptable and temporary
SURGICAL MEASURES
  • Surgery may be indicated for some complications
  • Organ transplants possible for lung, liver, pancreas
ACTIVITY

Physical conditioning to the extent possible for cardiorespiratory fitness (does not improve pulmonary function)

DIET
  • Allow liberal salting of foods per patient preference
  • High protein
  • High calories (1.5 x recommended for general population)
  • High fat (previously not recommended)
  • Vitamin supplements (double RDA)
  • May need supplemental feeds, oral or by gastrostomy
PATIENT EDUCATION

Written information and support: Cystic Fibrosis Foundation, 6931 Arlington Road, Ste. 2000, Bethesda, MD 20814, (800)344-4823

FOLLOW UP

PREVENTION/AVOIDANCE
  • In prenatal situations
    • Genetic counseling
    • Prenatal diagnosis for future pregnancies
  • For complications
    • For respiratory infections - maintain pertussis and measles immunity; annual influenza immunization
    • Avoid general anesthetics. Consider epidural, spinal, or local.
    • Good medical teamwork in the management of the multifaceted problems of the disease
POSSIBLE COMPLICATIONS
  • Atelectasis
  • Pneumothorax
  • Hemoptysis
  • Right heart failure
  • Pulmonary hypertension
  • Pulmonary emphysema
  • Digital clubbing
  • Hypertrophic pulmonary osteoarthropathy
  • Diabetes: affects growth, lung function
  • Metabolic alkalosis
  • Volume depletion
  • Bleeding esophageal varices
  • Symptomatic biliary cirrhosis
  • Intestinal obstruction
  • Female fertility rate about 80% of normal
  • Numerous psychosocial aspects
  • Malnutrition
  • Retarded growth
  • Hypovitaminosis A (increased ICP)
  • Hypovitaminosis E (chemolytic anemia)
  • Hypovitaminosis K (bleeding tendency)
EXPECTED COURSE AND PROGNOSIS
  • Largely dependent on pulmonary involvement
  • Prognosis improving due to early detection and aggressive treatment
  • Median survival is to age 31

MISCELLANEOUS

ASSOCIATED CONDITIONS
  • See Complications
  • Pansinusitis
AGE-RELATED FACTORS

Pediatric: Diagnosis usually confirmed in infancy or early childhood but some go undetected until adolescence. Newborn screening methods are in development. Psychosocial considerations
Geriatric: N/A
Others: N/A

PREGNANCY

If cystic fibrosis patient's condition (pulmonary and nutrition) good at start of pregnancy, usually returns to that level following birth. If these conditions are compromised before pregnancy, they may deteriorate following birth.

OTHER NOTES
  • Advise genetic counseling for at-risk individuals
  • Encoded protein on long arm of chromosome 7 contains 1480 amino acids
  • Multiple types of gene defects are possible (>500 defined). Most common mutation (70%) is DeltaF 508.
ABBREVIATIONS

CF = cystic fibrosis
IPPB = intermittent positive pressure breathing

Clinical Investigations

ROLE OF HOMOEOPATHY

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