Cystic Fibrosis Flashcards
What is cystic fibrosis?
Genetic disease resulting from abnormalities in the cystic fibrosis transmembrane conductance regulator. A chloride channel found in cells lining the lungs, intestines, pancreatic ducts, sweat glands and reproductive organs
What are some of the common clinical manifestations of Cystic Fibrosis?
Calorie malabsorption, lung disease which results from a cycle of mucus retention, infection and inflammation.
Describe the pathophysiology of cystic fibrosis
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) which results in abnormal salt transport by epithelial cells. Resulting in thick, sticky secretions
How does CF affect the pancrease?
Blockage of exocrine ducts, early activation of pancreatic enzymes and eventual autodestruction of exocrine pancreas. Leads to need for supplemental pancreatic enzymes
How does it impact the intestinal system?
Abnormal salt and water imbalance can lead to inspissations of stool and intestinal mucus which results in intestinal obstruction
What is the impact of CF on the lungs?
The absence of CFTR function results in mucus retention, chronic lung infections and inflammation which eventually leads to destruction of lung tissue. Lung disease is the most common cause of mortality
How do people commonly present with CF
Generally presents in infants or early childhood with faltering growth. Some may present with prolonged or severe bronchiolitis or recurrent respiratory complaints. Adults may present with chronic or recurrent bronchitis, sinusitis or pancreatitis.
When enquiring about birth history what should you ask about?
Passage of meconium (because delayed passage may be a sign) and the place of birth (many countries offer CF screening.
What should you enquire about with respiratory tract history?
- Resp rate, presence of retractions, cough or wheeze.
- Presence of cough and quantity and quality of sputum.
- History of lower airway infections
- Haemoptysis
What should you enquire about with GI tract history?
- Appetite, typical diet, stool habits, gastro-oesophageal reflux.
- Presence on insatiable appetite along with large, bulky or greasy stools. This is consistent with fat and calorie malabsorption.
- History of decreasing stools over time with/without abdo distention and vomiting as this may signal bowel obstruction.
- Recurrent pancreatitis/acute appendicitis
Name some of the findings on physical examination?
- Appearance of malnutrition.
- Increased anteroposterior diameter of the chest and crackles at auscultation.
- Clubbing of the hands
- Palpation of abdoment may reveal stool mass (RLQ), enlarged liver, spleen or both.
- Males - bilateral absense of vas deferens
Describe some of the investigations
- Sweat test
- Genetic testing (looking for most common CFTR mutations but there are over 2000 mutations that cause it)
- Sinus X-ray, deep throat swab
Describe features of the sweat test?
Small amount of pilocarpine is placed on the skin and the area is then stimulated by a small current for 5mins to stimulate sweating. The sweat is collected in a microcapillary tube and chloride content is measured. Considered the most conclusive test for diagnosis. Negative sweat test <30mmol/L. Positive sweat test >60mmol/L
What are the advantages of the sweat test?
Painless, relatively inexpensive, provides results in a few hours and accurate.
Describe the management of cystic fibrosis in regards to respiratory disease
- Augmented airway clearance and use of antibiotics to treat pulmonary clearance. The airway clearance should be preformed to mobilise secretions so they can be coughed out.
- Mucus thinners
