Cystic Fibrosis (Reading & Sharing)

Systic fibrosis is an inherited autosomal recessive disease in which abnormally thick mucus affects the reproductive, gastrointestinal, and respiratory tracts. Cystic fibrosis causes respiratory disease, characterized by chronic infection, obstructive airway disease, and progressive decline in lung function. Death is most commonly the result of respiratory failure. The life expectancy of patients with cystic fibrosis has increased to the mid-30s as a result of advances in treatment. Adult palliative care providers will be caring for more patient with cystic fibrosis as life expectancy of these patients continues to increase.

Cystic fibrosis (CF) is an autosomal recessive disorder affecting the exocrine glands, causing abnormal viscosity of secretions. it primarily affects the pulmonary and GI systems. Approximately 4% to 5% of Caucasians are symptomless carriers of the CF gene. Slightly more males than females are affected. Incidence is estimated at approximately 1 in 3200 live Caucasian births. CF is found in all racial groups. There are approximately 30000 people living with CF in the United States. 45% of whom are age 18 or older. Presently the predicted survival age extends to the late 30s, compared with a life expectancy of less than 1 year in the 1950s.

• the most common fatal hereditary disorder of whites in the US and second most common life-shortening childhood-onset inherited disorder in the US, behind sickle cell disease.
• median age at diagnosis is 5.3 months, median survival is 37 years.

Pathophysiology & Etiology

• caused by genetic defect in a single gene located on the long arm of chromosome 7 that encodes the cystic fibrosis transmembrane conductance regulator, and the cystic fibrosis transmembrane conductance regulator is responsible for the fluid balance across epithelial cells. The malfunction of the cystic fibrosis transmembrane conductance regulator results in:
  1. decreased chloride secretion into the airway lumen
  2. increased sodium reabsorption, which leads to decreased airway surface liquid volume
  3. thickened mucus, impaired mucocillary clearance, chronic infection, plugged bronchi
  4. chronic inflammation, airway damage, atelectasis and hyperinflation of lungs
  5. progressive bronchiectasis, irreversible fibrotic changes in lungs
• GI and pancreatic involvement includes:
  1. acini and ducts of pancreas become filled with thick mucus and are obstructed
  2. trypsin, chymotrypsin, lipase, and amylase do not reach the small intestine causing digestion is impaired.
  3. Interruption of the enterohepatic circulation of bile acids probably results in interference with normal pancreatic lipolysis and fat absorption through the intestinal wall.
  4. stools are abnormal and indicate malabsorption syndrome
  5. meconium ileus often occurs in infants, indicating that bowel is obstructed by thick intestinal secretions
  6. biliary cirrhosis occurs because the intrahepatic biliary tract is obstructed by thick secretions
  7. and in 30% of CF patients, the gallbladder is small, with suboptimal function. Gallstones develop in up to 10% of patients

• Sweat gland involvement includes:
  1. Secretions contain excessive amount of sodium and chloride, leading to excessive loss, especially with hot weather, fever, or exertion
  2. Saliva also contains an excess of sodium and chloride

Clinical Manifestations – usually occurs younger than age 6 months, but may occur at any age-

• Respiratory
  • recurrent pulmonary infections
  • chronic cough, dry to productive- chronic clearing of throat may indicate increased mucus production
  • wheezing, crackles on auscultation are indicative of respiratory exacerbation (Basilar crackles and hyperresonance to percussion)
  • dyspnea
  • barrel-shaped chest (increased anteroposterior chest diameter)
  • cyanosis
  • clubbing of fingers and toes
  • nasal polys and pansinusitis
  • progressive chronic obstructive pulmonary disease (COPD)
• GI
  • meconium ileus found in neonates
  • failure to thrive and failure to gain weight in the presence of a good appetite
  • abdominal distention
  • vomiting, dehydration, and electrolyte imbalance
  • maldigestion, steatorrhea (fatty stools- greasy and smelly feces, loss of fat-soluble vitamins)
  • rectal prolapse
  • distal intestinal obstructive syndrome
  • biliary cirrhosis, obstructive jaundice
  • pancreatitis
• Others
  • thin extremities, sallow skin, wasted buttocks
  • hyperglycemia, glucosuria, polyuria, weight loss
  • salty taste when parents kiss skin
  • sterility in males
  • hypoproteinemia and anemia
  • bleeding diathesis
  • hyponatremia and heat prostration
  • kyphosis

TO BE CONT….