The respiratory system - Lung infections Flashcards
(115 cards)
How is cystic fibrosis (CF) inherited?
It is an autosomal dominant - both parents must be carriers for child to have it
What gene is affected in CF?
Mutations to the cystic transmembrane conductance regulator (CFTR) gene on the long arm of chromosome 7
What is the role of the cystic fibrosis transmembrane conductance regulator (CTFR) gene?
The CTFR gene encodes for an epithelial chloride channel regulated by cyclic AMP. This channel help maintain the right balance fluid in the airways.
What is the most common CF mutation
Delta F508
What is the description for the following classes of CFTR mutation:
a) stage I
b) Stage II
c) Stage III
d) Stage IV
e) Stage V
a) No functional CFTR is made
b) Defective protein processing
c) Defective regulation
d) Defective conduction
e) Reduced functional CFTR
Describe the pathogenesis of cystic fibrosis
- Defects in the CTFR gene lead to defects in the normal ion transport
- This result in dehydration of airway surface resulting in mucociliary dysfunction
- This leads to reduced mucus clearance, airway obstruction and predisposition to infection
- Recurrent infection leads to chronic bronchitis, damage to the bronchi and eventually bronchiectasis
What are the clinical features of CF in new-borns
Meconium ileus (a bowel obstruction that occurs when the meconium in a child’s intestine is even thicker and stickier than normal meconium)
What are the clinical features of CF in infants/children
- Pancreatic insufficiency (Failure to thrive)
- Hepatic steatosis (Fatty stools)
- Recurrent chest infections
- failure to thrive
- Rectal prolapse
- Dehydration
- Allergic bronchopulmonary aspergillosis (ABPA)
- Renal calculi
- Distal intestinal obstruction syndrome (DIOS)
- Hyponatraemic hypochloraemic metabolic alkalosis
What are the clinical feature of CF in adolescence/adulthood
- Chronic sinusitis
- Nasal polyps
- Bronchiectasis
- Liver disease
- Steatorrhea
- Constipation
- Distal intestinal obstruction syndrome (DIOS)
- Male infertility
- Arthritis/arthralgia
- Delayed puberty, Osteoporosis
- Finger clubbing
- Gallstons
- Pancreatic insufficiency
- Pancreatitis
- Diabetes
- Renal calculi, renal failure
Exacerbation of pulmonary infections in patients with cystic fibrosis
a) Symptoms
b) Signs
a)
- Increased frequency and duration of cough
- Increased sputum production
- Change in appearance of sputum
- Increased SOB
- Decreased exercise tolerance
- Decreased appetite
- Feeling of increased congestion in the chest
b)
- Increased respiratory rate
- Use of accessory muscles for breathing
- Intercostal retractions
- Change in results of auscultatory examination of chest
- Decline in measures of pulmonary function consistent with presence of obstructive airway disease
- Fever and leukocytosis
- Weight loss
- New infiltrate on chest radiograph
Describe the 4 common clinical manifestations of cystic fibrosis
Respiratory disease
- Most common
- Persistent, daily, productive cough
- Recurrent infections result in bronchiectasis
- Complications: cor pulmonale, haemoptysis and pneumothorax
Pancreatic disease
- CF-related disease
- Fatty stools
- Malabsorption
Gastrointestinal disease
- Most common cause of meconium ileum in infants
- Constipation
- Distal intestinal obstruction syndrome (DIOS))
Malignancies
- Increased risk of GI malignancies
Why do CF patients get fatty stools and malabsorption?
Thick secretions block the outflow of exocrine digestive enzymes leading to insufficiency with fatty stools and malabsorption
Describe the screening of CF in the UK
CF is screened for as part of new-born heel prick test
Conducted at day 5 after birth
Give 3 tests that can be used to diagnose CF
Heel prick test (detects immunological-reactive trypsin)
Sweat test
Genetic testing
What are the diagnostic result of the sweat test in CF?
Sodium chloride of > 60 mmol/L is diagnostic
Describe the CXR changes in CF
Hyperinflation
Reticulonodular shadowing
Collapse/atelectasis
Bronchiectasis
Describe the management of pulmonary disease in CF
Conventional
- airway clearance techniques
- Chest physiotherapy
Pharmacological (Mucoactive agents)
1. rhDNase - 1st line and given via nebuliser
2. Hypertonic sodium chloride - may be used alone or with rhDNase. Given via nebuliser
3. Mannitol dry power inhalation - used in patients intolerant, ineligible or not responding to rhDNase. It is inhaled
Pulmonary infection
- Prophylactic antibiotics/antifungal + steroids e.g., ABPA
Lung transplantation
- Can be considered in patients with progressive respiratory failure and usually both lungs
How are CF patients with new infections (psudeomonas aeruginosa) treated?
Treat with eradication therapy with oral/IV antibiotics and inhaled antibiotics.
If clinically unwell then only IV and inhaled antibiotics used
What antibitoic can be offered in CF children from age 3-6 years?
Oral flucloxacillin
Describe the management of nutrition and pancreatic insufficiency in CF
Nutrition
- Nutritional assessment and reviews offered with a specialist dietician
- If wight loss/inadequate weight gain increase portion size + eat high-energy foods. Nutritional supplements can be considered if unsuccessful
- Ongoing deficit may need enteral feeding or trial of oral appetite stimulant
Pancreatic insufficiency
- Oral pancreatic enzyme replacement (e.g., CREON)
Describe the management of liver disease in CF
- Patients screen regularly
- Ursodeoxycholic acid can be given
- Transplantation: may be indicated in those with liver failure (completed alone or as a liver-lung or liver-pancreas transplant)
Describe the management of CF-related diabetes
- Should be screened annually from age of 10 and at any times where symptoms are suggestive
- Treat diabetes e.g., insulin
.Several new therapies for the management of cystic fibrosis known as CFTR modulators have been approved for use in the UK.
a) Describe their mechanism of action
b) Name the 4 drugs available in the UK
a) Target the underlying mechanism in cystic fibrosis
b) Kalydaco, Orkambi, Symkevi and Kaftrio
What is bronchiectasis?
Bronchiectasis is the irreversible and abnormal dilatation of the airways