Resp conditions Flashcards
What is the pathophysiology of cystic fibrosis
- mutation in the cystic fibrosis transmembrane receptopor
- results in impaired chloride secretion
- causes sodium and water to move into cells leaving viscous secretions behind
- this predisposes to infection
What type of inheritance pattern is cystic fibrosis
autosomal recessive
Why is sweat high in sodium in patient with cystic fibrosis
Primary secretion of sweat duct is normal but CFTR does not absorb chloride ions, which remain in the lumen and prevent sodium absorption.
Why is pancreatic insufficiency a feature in patients with cystic fibrosis
Production of pancreatic enzymes is normal but defects in ion transport produce relative dehydration of pancreatic secretions, causing their stagnation in the pancreatic ducts.
Why is cystic fibrosis associated with gastrointestinal disease
Low-volume secretions of increased viscosity, changes in fluid movement across both the small and large intestine and dehydrated biliary and pancreatic secretions cause intraluminal water deficiency.
Why is biliary disease associated with cystic fibrosis
Defective ion transfer across the bile duct causes reduced movement of water in the lumen so that bile becomes concentrated, causing plugging and local damage.
How does cystic fibrosis effects the resp system
- Dehydration of the airway surfaces reduces mucociliary clearance
- This favours bacterial colonisation
- local bacterial defences are impaired by local salt concentrations and bacterial adherence is increased by changes in cell surface glycoproteins.
- Increased bacterial colonisation and reduced clearance produce inflammatory lung
Which mediators are involved in the neutrophilic response in CF that causes inflammatory lung damage
IL8
Neutrophil elastase
What screening is available to detect CF
- immunoreactive trypsinogen (IRT) on blood spot Day 6
- abnormally raised IRT levels will undergo CFTR mutation screening
What are the key signs in CF
Finger clubbing. Cough with purulent sputum. Crackles. Wheezes (mainly in the upper lobes). Forced expiratory volume in one second (FEV1) showing obstruction.
What presentation of CF may be picked up perinatally
- Screening.
- Bowel obstruction with meconium ileus (bowel atresia).
- Haemorrhagic disease of the newborn.
- Prolonged jaundice.
What presentation of CF may be picked up in infancy and childhood
- FH
- Recurrent respiratory infections.
- Diarrhoea.
- Failure to thrive
- Nasal polyps
- Acute pancreatitis.
- Portal hypertension and variceal haemorrhage.
- Pseudo-Bartter’s syndrome, electrolyte abnormality.
- Hypoproteinaemia and oedema.
How may adolescence present with CF
Family history. Recurrent respiratory infections. Atypical asthma. Bronchiectasis. Chronic pulmonary disease. Chronic sinus disease. Male infertility with congenital bilateral absence of the vas deferens. Heat exhaustion/electrolyte disturbance. Portal hypertension and variceal haemorrhage.
What investigations should be done is suspecting CF
- sweat test
- molecular genetic testing
- CT chest/CXR
- lung functions test (>6yrs)
- Sputum microbiology
What findings on sweat test would be indicative of CF
- Chloride concentration >60 mmol/L with sodium concentration lower than that of chloride on two separate occasion
- > 98% sensitive
what common bacteria are often found in sputum of patients with CF
- Haemophilus influenzae
- Staphylococcus aureus
- Pseudomonas aeruginosa
- Burkholderia cepacia
- Escherichia coli
- Klebsiella pneumoniae.
What is the progressive pathology of resp disease in CF
- chronic infection and inflammation
- bronchiectasis
- progressive airflow obstruction
- cor pulmonale
- death.
What is the management of CF
- Chest physio!! BD - more in acute infection
- regular sputum samples
- prophylactic Abx - staph aureus (fluclox)
What is the management of chronic P. aeruginosa
nebulised colistimethate sodium or tobramycin
What is an episodic viral wheeze
Inflammation and constrition of the bronchi as a result of viral infection causing wheeze
Would you treat every child with an episodic viral wheeze
no - only if symptomatic with difficulty breathing
What are the two patterns of wheeze in pre-schoolers
episodic viral wheeze
multiple trigger wheeze
What is a multiple trigger wheeze
wheeze associared with other triggers such as exercise, exposure to allergens or smoke.
Part of the atopic march
What is the atopic march
- Eczema
- Food allergies - cows milk protein, nuts and egg
- allergic rhinitis
- asthma
How many resp tract infections would you expect to see in a pre-schooler per year
6
What features may indicate a child is going to develop asthma if experienced VIW during the first 3 years of life
Major:
- Parental history of asthma
- Doctor diagnosed atopic dermatitis
Minor
- Blood eosinophils >4%
- wheezing unrelated to colds
- doctor diagnosed allergic rhinitis
What is the definition of asthma
Children presenting with recurrently episodes of wheeze and breathlessness fluctuating over time and with treatment
often in the contect of an atopic background
What is the management for mild, intermittent symptoms in children under 12
SABA - salbutamol
What is the management of asthma in children under 5
- Regular ICS or montelukast if steroid can’t be used
- Add on montelukast (leukotriene receptor antag)
- Increase ICS
- high dose therapies - ? add 4th drug - slow release theophylline - REFER TO SPECIALIST
What defines complete control of asthma
- no daytime or nightime symptoms/waking
- no need for rescue medication
- No asthma attacks
- no limitations on exercise/activity
- PEF >80s% predicted
- minimal side effects from medications
What is considered a chronic cough
> 8 weeks
most viral coughs will clear in 3-4 weeks
What are common causes of chronic cough in children
- TB
- postnasal drip
- reflux (GORD)
- environmental agents- smoke
- asthma
What are rare causes of chronic cough in children
- Inhaled foreign body.
- Cystic fibrosis.
- Immune deficiency.
Congenital lesions - eg, tracheo-oesophageal fistula, tracheomalacia. - Ciliary dyskinesia.
- Neurological - eg, tics, psychogenic cough. Psychogenic cough may be bizarre, honking and decrease with sleep or attention to other activities
- recurrent aspiration
What are the red flags for chronic cough
- Family history of lung disease.
- Neonatal onset.
- Sudden onset.
- Haemoptysis
- Cough with feeding, dysphagia, severe vomiting.
- Chronic moist cough with sputum production.
- Night sweats/weight loss.
- Continuous unremitting or worsening cough.
What are the red flag signs of a chronic cough
- Signs of chronic lung disease - eg, clubbing.
- Failure to thrive.
- Abnormal voice or crying, inspiratory stridor.
- Focal chest abnormality.
