Cystic Fibrosis Flashcards
Define cystic fibrosis
Severely life-shortening genetic disease resulting from abnormalities in the cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel found in cells lining the lungs, intestines, pancreatic ducts, sweat glands, and reproductive organs,
What is the aetiology of cystic fibrosis
Autosomal recessive
80% are due to delta F508 on the long arm of Chr 7
Mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) (anion/chloride channel found in the membrane of epithelial cells) - can be homo/heterozygous
→ abnormal salt transport by epithelial cells → thick, sticky secretions
Pancreas: blockage of exocrine ducts, early enzyme activation, autodestruction of the pancreas
Intestine: bulky stools → intestinal blockage
Lungs: Mucus retention, chronic infection, inflammation → lung tissue destruction
What are the common organisms implicated in respiratory tract infections in those with cystic fibrosis
Staph aureus
Pseudomonas aeruginosa
H. Influenzas
Burkholderia cepacia complex
Non-tuberculosis mycobacterium
Aspergillum fumigatus
What are the risk factors for cystic fibrosis
FHx CF
Known carrier status of both parents
Ethnicity: white
Genetic
- Cystic Fibrosis
- Ciliary dyskinesia or immotile cilia syndrome ± Kartagener’s syndrome
What is Kartagener’s syndrome
Autosomal recessive
Ciliary dyskinesia
Situs inversus
Chronic sinusitis
What are the symptoms of cystic fibrosis in young children
Pancreas (85%) and lungs most commonly affected
Neonatal Hx: Failure/delay to pass meconium, jaundice, bilious vomiting
Failure to thrive, poor weight gain, dropping percentiles
BUT voracious appetite
Cough (wet, prolonged, hard coughing spells, ± haemoptysis)
Recurrent infections
Chronic sinusitis and coryzal symptoms
Pale, fatty, foul-smelling, floating stools (steatorrhoea)
Gastro-oesophageal reflux
What are the symptoms of cystic fibrosis in older children
Hx pancreatitis: acute abdominal pain, nausea, vomiting
Symptoms of diabetes mellitus
Delayed puberty
Short stature due to malnutrition
Male infertility
Nasal polyps
Rectal prolapse due to bulky stools
What are the signs of cystic fibrosis on examination
General: ?malnutrition (protuberant abdomen, lack of SC fat, short stature)
Hands: clubbing
Resp: wheeze, increased AP diameter of chest
Abdominal exam
Testicular: ?genital abnormalities
What are the differentials for cystic fibrosis
Primary ciliary dyskinesia
Primary immunodeficiency
Asthma
GORD
Chronic aspiration
FTT
Coeliac disease
Protein-losing enteropathy
How is cystic fibrosis tested for in neonates
Heel prick testing at 5 days → elevated immunoreactive trypsinogen
What investigations should be done for cystic fibrosis
Bedside
Stool for faecal elastase: low
Stool for chymotrypsin: low
Stool for microscopy: fat globules seen
Other
Sweat test (pilocarpine iontophoresis): +ve (sweat chloride >60mmol/L, 30-59 = intermediate → CF centre referral)
Immunoreactive trypsinogen testing: +ve → follow with confirmatory testing (sweat)
Genetic testing: presence of mutation
In which patients should a sweat test be performed in
FHx CF
Congenital intestinal atresia
Meconium ileus
Symptoms and signs that suggest distal intestinal obstruction syndrome
Faltering growth (in infants and young children)
Undernutrition
Chronic sinus disease
Obstructive azoospermia
Rectal prolapse
Acute/chronic pancreatitis
What is the management for cystic fibrosis
- Refer to a CF centre
MDT management: Paediatrician | Nurse | physiotherapist | dieticians | pharmacists | clinical psychologists | social workers
- Respiratory
- Infection
- Nutrition
- Psychological
- General management
Describe the respiratory interventions done for patients with cystic fibrosis
Increased monitoring with spirometry and symptom watches
Physiotherapy 2x a day
- Airway clearance manoeuvres and devices
- Encouraging physical activity
- Manual chest physiotherapy
- Active cycle breathing
- Use of chest wall oscillators or PEP devices
Mucolytic therapy:
First line: rhDNase (Dornase alfa) nebs
Second line: rhDNase + hypertonic saline
Third line: Mannitol dry powder (INH)
Orkambi: Lumacaftor with Ivacaftor (potentiators and correctors) - useful for F508 mutation (78% of CF)
Describe the infection interventions done for patients with cystic fibrosis
Minimise contact with other patients with CF
Prophylactic antibiotics
- Flucloxacillin and azithromycin
- Moderate/severe → tobramycin and oxacillin
Inhaled bronchodilator e.g. salbutamol metered-dose inhaler
Rescue packs (for prompt IV Abx with any symptoms or signs of infection)
End stage CF disease → lung transplant*
*chronic infection with Burkholderia cepacia is an important CF-specific contraindication to lung transplantation
