Cystic Fibrosis

Question 1

Cystic Fibrosis Is.. (2 facts)

Answer 1

1. autosomal recessive, inherited
2. multi system disease that is characterized by secretions of abnormally viscous bodily fluids, especially in the pancreas, lungs, and sweat glands

Question 2

CF Epidemiology (5 facts)

Answer 2

• Most common genetic disease among caucasians
• Most common cause of chronic lung disease in children and young adults
• Median age of diagnosis is six months
• About 30,000 patients in the US, about 1000 new cases per year
• prevalence is related to ethnicity (1/2500 caucasians)

Question 3

CF Etiology (4 facts)

Answer 3

• Autosomal recessive inheritance of mutations in a single gene
• Encodes for cystic fibrosis transmembrane regulator (CFTR)
• > 1900 mutations divided into 6 classes
• Most common mutation is the deletion of F508 (60-75%)

Question 4

CF Mutation Classes (6 classes)

Answer 4

Class I: No protein synthesized; no function (Nucleus)
Class II: No trafficking to the cellular surface; no function (ER)
Class III: No function at cell surface; no function
Class IV: Less function at the cell surface
Class V: Less protein at cell surface
Class VI: Less stable at cell surface

Question 5

CF Pathophysiology (4 facts)

Answer 5

• CFTR is a membrane bound Cl- channel
• Helps regulate fluid and electrolyte balance in epithelial cells lining airways, pancreatic ducts, and sweat glands
• Located on apical surface (facing the lumen, the opening)
• **Cl-, Na+ and water are always together

Question 6

CFTR Function and Dysfunction (sweat glands)

Answer 6

• CFTR is responsible for reabsorbing chloride from sweat and sodium follows the chlorine naturally through another channel.
• CFTR disfunction leads to sweat with more concentrated salts

Question 7

CFTR Function and Dysfunction (the lungs)

Answer 7

• CFTR dysfunction leads to Chlorine isolation inside of the lung cell.
• Na+ and h2o follow Cl- and are reabsorbed into the cell from the mucus
• The mucus becomes severely dehydrated and viscus and cannot move through the lungs in CF

Question 8

CF Pathophysiologic Triad (3 facts)

Answer 8

• Stepwise (in lungs): Viscous mucus in lung causes chronic infection, inflammation, airway obstruction, bronchiectasis (walls of bronchi are thickened by chronic inflammation) and bronchiolectasis
• Excess salt in sweat, saliva and tears
• Pancreatic enzyme deficiency causing poor digestion, malabsorption

Question 9

CF Pathophysiology in the lungs (4 factors)

Answer 9

CF results in:

1. Impaired endogenous antimicrobial enzymatic activity
2. Impaired mucocillary transport
3. Impaired other defenses
4. Inflammation, Remodeling, Genetic adaptation

Question 10

CF Diagnosis: Pulmonary

Answer 10

Clinical presentation varies with mutation (can also be pancreatic)
1. Pulmonary: Recurrent infection, obstructive lung disease, persistent cough, exercise intolerance, hemoptysis (coughing blood), tachypnea (rapid breathing), barrel chest, hypoxemia (decreased O2 to tissues because of decreased oxygen in lungs

Question 11

CF diagnosis: GI

Answer 11

Meconium ileus at birth (dehydration of the bodily fluid leads to baby first poop to become stuck and cannot pass pathognomonic-absolutely diagnostic), failure to thrive, steatorrhea (excessive fat in stool)

Question 12

CF diagnosis: Other

Answer 12

Digital clubbing, infertility (males)

Question 13

CF Patient Assessment (APS)

Answer 13

1. Arterial blood gas (how well oxygenated blood is)
2. Pulmonary function (spirometry, FEV, tidal volume, respiratory rate)
3. Sweat test (chloride sweat test)

Question 14

CF Sweat test

Answer 14

-Quantitative pilocarpine iontophoresis test (QPIT(:
1. Normal = 60 mEq/L
2. CF= >60mEq/L
For 40 to 60 mEq/L, retest and/or look for other clinical signs

Question 15

CF Complications: Acute

Answer 15

Common and usually serious
1. Acute: pneumonia, atelectasis (collapsed lung), pneumothorax (air leaking out of the lung), malnutrition, dehydration, pancreatitis, respiratory failure

Question 16

CF complications: Chronic

Answer 16

Bronchiectasis, nasal polyps, cirrhosis, cor pulmonale (pulmonary HT), diabetes mellitus

Question 17

CF Prognosis and Monitoring

Answer 17

1. No cure and disease progress with time
2. Principle cause of death is respiratory failure or resistant pulmonary infection
3. Ongoing patient monitoring
   - Pulmonary involvement determines disease severity and progression
   - Counseling and other psychosocial intervention

Question 18

CF Patient Assessment (GLS)

Answer 18

4) Genotyping (less than 100 possible mutations)
5) Lung assessment x-ray more diagnostic or treatment based in the latter time of disease
6) sputum culture