Respiratory Flashcards
what is chronic obstructive pulmonary disease
- chronic lung condition characterised by breathlessness due to poorly reversible and progressive airflow obstruction.
- chronic bronchitis and emphysema
- 1-4 % of population
pathology of chronic bronchitis
- inflammation and scarring of small bronchioles
- Mucous gland hyperplasia and irritant effects of smoke causes productive cough
pathology of emphysema
- inflammation and scarring of the small bronchioles
- Imbalance of proteases and antiproteases causes destruction of the lung parenchyma with dilation of terminal airspaces (emphysema) and air trapping
pathophysiology of COPD
- hyperinflation, thick mucus, dilated terminal airways
- +/- bullae
- finely pigmented macrophages in the respiratory bronchioles
clinical manifestations of COPD
- exertional breathlessness, history of prolonged cough and sputum
- dyspnoea
- wheeze
- FEV1<80 FEV1/FVC<70
- cyanosis
- cor pulmonale (R heart enlargement)
pink puffers
- emphysema
- raised alveolar ventilation, a near normal PaO2 and a normal or low PaCO2.
- breathless but are not cyanosed
- may progress to type I respiratory failure
blue bloaters
- chronic bronchitis
- lowered alveolar ventilation, with a low PaO2 and a high PaCO2.
- cyanosed, may go on to develop cor pulmonale.
- Their respiratory centres are relatively insensitive to CO2 and they rely on hypoxic drive
investigations for COPD
- FBC = raised packed cell volume (PCV)
- CXR: hyperinflation, flat hemidiaphragms
- CT: bronchial wall thickening, scarring, air space enlargement
- ECG: right hypertrophy (cor pulmonale)
- ABG: low PaO2 with hypercapnia
- Spirometry: obstructive + air trapping
management for COPD
- exercise, weight loss, stop smoking
- mucolytics (dornase alfa)
- diuretics for oedema
- SABA or SAMA (muscarinic antagonist)
- may need long acting or ICS
acute exacerbations of COPD
- mostly in winter and triggered by infections
- increased cough, wheeze, breathlessness
- ABG, ECG, FBC, CXR
- ensure oxygenation then treat cause
- salbutamol, IV hydrocortisone, Abx
what is asthma
- A chronic inflammatory disorder of large airways characterised by recurrent episodes of reversible airway narrowing
- most associated with atopy (asthma, hay fever, eczema) = genetic tendency of immune system to produce IgE in response to common allergens
pathology of asthma
- produce large amount of allergen specific IgE = binds onto surface of mast cells
- re-exposure = IgE crosslink = degranulation of mast cells
- airway inflammation and bronchospasm
- ongoing inflammation = hypersensitive airways = react to exercise, cold air, cigarette smoke
features of asthma
- Inflammation of the mucosa
- Increased mucous production
- Bronchodilation
clinical manifestations of asthma
- Intermittent episodes of breathlessness, wheeze, and chest tightness
- Cough, particularly at night
- NSAIDs and B blockers can precipitate attack
- acid reflux
- poor sleep
- hyperinflated chest
investigations for asthma
- spirometry, reversibility test (spirometry will increase after dose of salbutamol)
- PEF
- CXR = hyperinflation (chronic asthma)
management of asthma
- step 1 = occasional SABA
- step 2 = + ICS (beclomethasone 200mcg/day)
- step 3 = Leukotriene receptor antagonist (LRTA, e.g. montelukast)
- 4 = LABA (e.g. salmeterol)
- 5 = Increase ICS dose
management of acute severe asthma attack (OSHIT)
- OXYGEN to maintain 94-98%
- SALBUTAMOL 5mg nebulised
- add IPRATROPIUM to nebuliser if life-threatening
- iv HYDROCORTISONE/ prednisolone
- THEOPHYLLINE IV (bronchodilator)
what is resp failure (type 1 and 2)
- Defined as arterial PO2 <8kPa.
- Type 1 = normal or low pCO2
- Type 2 = raised pCO2
causes of type 1 resp failure
- Severe pneumonia
- Pulmonary embolism
- Acute asthma
- Pulmonary fibrosis
- Acute LVF
causes of type 2 resp failure
- COPD
- Neuromuscular disorders impairing ventilation e.g. myasthenia gravis
- Reduced respiratory drive e.g. sedative drugs
pathology of resp failure (1 and 2)
1) increased ventilation removes CO2 but can’t compensate for low pO2 (ventilation/perfusion mismatch)
2) generalised alveolar hypoventilation
clinical features of resp failure
- hypoxia = dyspnoea, restlessness, agitation, confusion, central cyanosis (long standing hypoxia = pulmonary hypertension and cor pulmonale)
- hypercapnia = Headache, peripheral vasodilation, tachycardia, bounding pulse, tremor/flap, papilledema, confusion, drowsiness, coma
investigations for resp failure
- Blood tests: FBC, U&E, CRP, ABG
- Radiology: CXR
- Microbiology: sputum and blood cultures
- Spirometry
management of type 1 resp failure
- Treat underlying cause
- Give oxygen facemask
- Assisted ventilation if PaO2 <8kPa despite 60% O2
management of type 2 resp failure
- respiration driven by hypoxia
- treat cause
- controlled O2 therapy (start at 24% O2)
- recheck ABG after 20 min, if PaCO2 lower then increase O2 to 28%
- may need intubation and ventilation
what is hypersensitivity pneumonitis/ extrinsic allergic alveolitis
interstitial lung disease caused by an immunologic reaction to inhaled antigens
causes of hypersensitivity pneumonitis
- Thermophilic bacteria (mouldy hay, compost, air conditioner ducts)
- Fungi (mouldy maple bark, barley or wood dust)
- Avian proteins (bird droppings and feathers)
pathology of hypersensitivity pneumonitis
- Inhaled antigens lead to an abnormal immune reaction in the lungs
- antibody (type 2), immune complex (type 3) and cell-mediated (type 4) hypersensitivity reactions
clinical manifestations of hypersensitivity pneumonitis
- acute disease = severe breathlessness, cough and fever 4-6h after large exposure, resolves in 12-18h
- chronic disease = prolonged exposure to small amount of antigen, gradual onset of breathlessness, dry cough, fatigue, clubbing, weight loss, type1 RF
investigations for hypersensitivity pneumonitis
- High resolution CT shows middle to upper lobe-predominant linear interstitial opacities and small nodules
- chronic = honey comb lung on CXR, ground glass appearance on CT
management of hypersensitivity pneumonitis
- identify cause and avoid
- persistent exposure = fibrosis and honeycomb
- acute =O2, PO prednisolone, reducing course
- chronic = avoid allergen or wear facemask, long term steroids
Coal worker pneumoconiosis
- inhalation of coal dust particles over 15-20yrs
= ingested by macrophages which die, releasing enzymes and causing fibrosis
-CXR = round opacities in upper zone
progressive massive fibrosis
- due to progression of CWL
- dyspnoea, fibrosis, cor pulmonale
- CXR = fibrotic masses in peripheries of upper-mid zone
Caplan’s syndrome
The association between rheumatoid arthritis, pneumoconiosis, and pulmonary rheumatoid nodules
silicosis
- inhalation of silica particles, very fibrogenic
- metal mining, stone quarrying, pottery
- CXR = nodular pattern, egg-shell calcification of hilar nodes
- increases risk of TB
- spirometry = restrictive
asbestosis
- causes pulmonary fibrosis
- dyspnoea, clubbing, fine-end crackles
- increased risk of bronchial adenocarcinoma and mesothelioma
byssinosis
- cotton mill worker
- symptoms start on first day back then improve through week
- endotoxins in bacteria in raw cotton
- no CXR changes
what is bronchiectasis
- abnormal permanent dilation of bronchi accompanied by inflammation in their walls and in adjacent lung parenchyma
- causes in developed countries = obstruction due to tumour/foreign body or CF related
- post infection (measles, pertussis, bronchiolitis, pneumonia, TB, HIV)
pathology of bronchiectasis
- weakening in bronchial walls caused by recurrent inflammation
- Scarring in the adjacent lung parenchyma places traction on the weakened bronchi, causing them to permanently dilate.
- Permanent thinning of these airways.
- Main organisms: H. influenzae, Strep. Pneumoniae, Staph. Aureus, Pseudomonas aeruginosa
signs and symptoms of bronchiectasis
- Persistent cough, Copious purulent sputum, Intermittent haemoptysis
- Finger clubbing, Coarse inspiratory crepitations, Wheeze
complications of bronchiectasis
- Pulmonary hypertension and RVF
- Pneumothorax
- Deposition of serum amyloid A protein in β-pleated sheets in multiple organs (AA amyloidosis)
investigations for bronchiectasis
- Sputum culture
- CXR: cystic shadows, thickened bronchial walls
- spirometry = obstructive
- bronchoscopy
management of bronchiectasis
- Airway clearance techniques (chest physio) and mucolytics
- Abx
- bronchodilators
- surgery if severe haemoptysis
what is cystic fibrosis
- An inherited disorder caused by a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene
- AR
- CFTR is on chromosome 7q and codes for a chloride ion channel
pathology of CF
- deletion of phenylalanine 508 (F508 mutation) causes abnormal folding of the CFTR protein
- Lack of normal CFTR = defective electrolyte transfer across epithelial cell membranes = thick mucus secretions
clinical manifestations of CF
- Neonate: failure to thrive, meconium ileus (cause bowel obstruction), rectal prolapse
- Children and young adults: cough, wheeze, recurrent infections, pancreatic insufficiency (DM), gallstones, cirrhosis, male infertility, osteoporosis, arthritis, vasculitis, nasal polyps
- liver failure develops late
investigations for CF
- neonatal screening = raised serum immunoreactive trypsin
- sweat test = sodium and chloride >60mmol/L
- CXR = hyperinflation, bronchiectasis
- abdo US = fatty liver, cirrhosis, chronic pancreatitis
- spirometry = obstructive
management of CF
- multidisciplinary
- chest physio (postural drainage), bronchodilators
- Abx for infective exacerbations
- treat other symptoms (eg DM), fat-soluble vitamins
- may need ventilation or lung transplant later on
what is a pleural effusion
- accumulation of excess fluid within the pleural space
- Blood = haemothorax
- Pus = empyema
- Chyle (lymph with fat) = chylothorax
- Both blood and air = hemopneumothorax