PANCE Blueprint Pulmonary (12%)

Cystic fibrosis

Patient will present as → a 3-year-old girl with growth retardation has a long history of recurrent pneumonia and chronic diarrhea. Her mother states that he has 6-8 foul smelling stools per day. Physical exam reveals a low-grade fever, scattered rhonchi over both lung fields, crepitant rales at the left lung base and dullness to percussion. Other findings include mild hepatomegaly and slight pitting edema of the lower extremities. CXR reveals hyperinflation, mucus plugging, and focal atelectasis. Labs reveal an elevated quantitative sweat chloride test.

Cystic fibrosis is an autosomal recessive disorder that results in the abnormal production of mucus by almost all exocrine glands, causing obstruction of those glands and ducts.

Although the lungs are generally histologically normal at birth, most patients develop pulmonary disease beginning in infancy or early childhood. Mucus plugging and chronic bacterial infection, accompanied by a pronounced inflammatory response, damage the airways, ultimately leading to bronchiectasis and respiratory insufficiency.

Non-pulmonary - pancreatitis and steatorrhea - patients will need supplementation of fat-soluble vitamins

The course is characterized by episodic exacerbations with infection and progressive decline in pulmonary function.

  • Mean survival is about 31 years of age

An elevated quantitative sweat chloride test performed on two different days is diagnostic.

  • ↑ NaCL > 60 mEq/L
  • However a normal result does not exclude the diagnosis, if strongly suspected, DNA testing can provide definitive evidence of cystic fibrosis.

CXR may reveal hyperinflation, mucus plugging and focal atelectasis

***Initially in the first few months of life, respiratory infection is common with Staphylococcus aureus and Haemophilus influenzae

  • After that Pseudomonas aeruginosa becomes the major causative organism for infections

Therapies focus on:

  • Clearing the airway of secretions - Chest physiotherapy
  • Reversing bronchoconstriction
  • Treating respiratory infections (treat for pseudomonas)
  • Replacement of pancreatic enzymes supplement fat soluble vitamins (A, D, E, K)
  • Nutritional and emotional support - high fat diet
Cystic fibrosis

CXR may reveal hyperinflation, mucus plugging and focal atelectasis

IM_MED_CysticFibrosisTreatment_v1.4_ Cystic fibrosis is a hereditary disease leading to problems with Cl- channels in the body. It is the most common lethal genetic disease in the Caucasian population. Patients develop recurrent pulmonary infections, bronchitis, infertility, pancreatic insufficiency, steatorrhea and malabsorption.

Question 1
Which of the following is essential to make a diagnosis of cystic fibrosis?
A
Positive family history
Hint:
Cystic fibrosis is a genetic disease, but a positive family history in and of itself is not enough to diagnose the condition.
B
Elevated sweat chloride
C
Recurrent respiratory infections
Hint:
While recurrent respiratory infections are a classic presentation of cystic fibrosis, the diagnosis relies on confirmation, as noted in explanation B.
D
Elevated trypsinogen levels
Hint:
Trypsinogen levels are used as a neonatal screening test and if elevated should be followed by more definitive testing to confirm the diagnosis.
Question 1 Explanation: 
The diagnosis of cystic fibrosis is made only after an elevated sweat chloride test or demonstration of a genotype consistent with cystic fibrosis.
Question 2
A pediatric patient presents with a history of multiple recurrent respiratory infections associated with failure to thrive. A sweat chloride test is elevated. Which of the following is a common cause of death in patients with this condition?
A
Diabetic ketoacidosis
Hint:
While patients with cystic fibrosis most likely will eventually develop insulin-dependent diabetes mellitus, diabetic ketoacidosis is not a common cause of death.
B
Pulmonary infection
C
Intestinal obstruction
Hint:
While intestinal obstruction may occur in patients with cystic fibrosis, it is not a common cause of death.
D
Acute respiratory failure
Hint:
See B for explanation.
Question 2 Explanation: 
This patient has cystic fibrosis. The most common causes of death include pulmonary complications, such as infections, and terminal chronic respiratory failure associated with cor pulmonale.
Question 3
A 3 year-old male with cystic fibrosis develops pneumonia. Which of the following is the most likely etiology of the pneumonia?
A
Escherichia coli
Hint:
See C for explanation.
B
Staphylococcus epidermidis
Hint:
See C for explanation.
C
Pseudomonas aeruginosa
D
Streptococcus pneumoniae
Hint:
See C for explanation.
Question 3 Explanation: 
Initially in the first few months of life, respiratory infection is common with Staphylococcus aureus and Haemophilus influenzae, but after that Pseudomonas aeruginosa becomes the major causative organism for infections.
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