Respiratory S6 (Done) Flashcards
What is the NICE definition of COPD?
COPD is characterised by airflow obstruction that is progressive and not fully reversible
Does not change markedly over several months
Predominant cause is smoking
What are the two processes occuring in COPD?
Chronic bronchitis
Emphysema
Patients may have features of either or both
Describe emphysema
Loss of alveolar surface and impairement of gas exchange resulting from destruction of terminal bronchioles and distl airspaces
Often progresses to creating larger redundant airspaces in the lung called bullae
Also causes destruction of the supporting tissues surrounding small airways which therefore tend to close during expiration when pressure outside airway rises. This results in Airflow obstruction
Additionally the loss of elastic tissues cause the lungs to hyperinflate as they are unable to resist the tendency of the rib cage to expand
Describe Chronic bronchitis
Characterised by an inflammatory process that leads to proliferation of mucus secreting cells in the large airways epithelium
This causes mucus hypersecretion and remodelling of inflammed airways
Excess mucs can lead to chronic productive cough and frequent repiratory infections
What are the causes of COPD?
Smoking (most)
Alpha-1-antitrypsin deficiency
Occupational exposure (E.g. Coal dust)
Pollution
What proportion of smokers get COPD?
15%
What are the predominant symptoms of COPD?
Cough and sputum production often occur first
Patients present when initially become breathless, this is progressive
Exacerbations associated with increase in all three symptoms compared to baseline, may be infective
How is breathlessness graded?
MRC dyspnoea score
- Breathlessness on strenuous exercise
- Breathlessness on slight hill or hurrying
- Walks slower than contemporaries on flat ground due to breathlessness or has to stop for breath when walking at normal pace
- Stops for breath every 100m or every few minutes on flat ground
- Too breathless to leave house or breathless when dressing and undressing
What are the signs of COPD?
‘Pursed lip’ sign:
Increases pressure in airways to cause reduction or delay in airway closure
Tachypnoea
Bracing arms to utilise accessory muscles:
Hyperinflation of chest:
Cause of breathlessness as diaphragm and accessory muscles must work harder to ventilate
Wheeze or quiet breath sounds
Cyanosis
CO2 retention
Cor Pulmonale (w/oedema)
How can airflow obstruction be measured and what use is this in COPD patients?
What spirometry measurements indicate obstructive pathology?
Spirometry:
Can be used to diagnose and track COPD and severity of airflow obstruction
Measurements:
FEV1/FVC ratio of <70% (FEV1 reduced) = Obstructive
FEV1 of 50-80% predicted = Mild obstruction
FEV1 of 30-49% predicted = Moderate obstruction
FEV1 of <30% predicted = Severe obstruction
How is COPD diagnosed?
Combination of suggestive symptoms, signs and airflow obstruction
Common suggestive features:
Smoker or Ex smoker
Older (>40) and late in life onset
Chronic productive cough
Breathlessness (persistent and worsening)
What other investigations might you perform on someone with suspected COPD and why?
CXR:
To exclude other Dx
High resolution CT scan:
Detailed assessment of degree of macroscopic alveolar destruction, helpful for considering surgery or if diagnosis is in doubt
ABG:
Assess for resp failure
Alpha-1-antitrypsin blood test:
Common for yound patients
What is involved in stable COPD care?
SMOKING CESSATION
Pulm. Rehab
Drugs
Diet - supplements/dietician review
Supportive - E.g. Flu vaccine
Long term O2 therapy if appropriate
Lung volume reduction if appropriate
Education - Inhaler technique
What drugs might be used in COPD?
Bronchodilators (E.g. B2 agonists)
Steroids (inhaled)
Anti-muscarinics
Mucolytics
Methylxanthines
What can be the side effects of B2 agonists such as salbutamol?
Tachycardia (atrial B2 receptors)
Tremor (Skeleatal B2 receptors)
Anxiety
Palpitations
Hypokalaemia (Intake of K+ in skeletal muscle)
What is the mechanism of action of Anti-muscarinic drugs?
Give an example of such a drug
Blocks Muscarinic Ach receptors in airways causing the airways to relax/widen
E.g. Ipratropium Bromide
What are the adverse effects of Anti-muscarinic drugs?
Dry mouth and cough
Pharyngitis
URTI
Nausea
Supraventricular tachycardia
Atrial fibrillation
Urinary retention
Constipation
Why are Methylxanthines used in COPD?
What are their side effects?
Why:
Bronchodilators
Increase respiratory drive
Increase strength of respiratory muscles
Anti-inflammatory
Side effects:
Tachycardia, SVT, Nausea, Seizures
Hence needs blood level monitoring!
Give the mechanism of action of Methylxanthines and two examples
Inhibition of phosphodiesterases:
PDEs break down cAMP, inhibition leads to increase in cAMP leading to bronchodilation etc.
Examples:
Aminophylline
Theophylline
Above what dose of inhaled steroids do side effects start to commonly occur?
Give examples of side effects
800mcg/day
Examples:
Thin skin/Bruising
Osteoporosis
Diabetes
Adrenal insufficiency
Mental disturbance
Fluid retention
Proximal myopathy
Give an example of a mucolytic drug
Why are they useful in COPD treatment?
Carbocysteine
Useful to reduce sputum thickness, helping reduce airway resistance
What is the concept of ‘deconditioning’ and how does it apply to COPD?
Many patients with COPD avoid excersize and strain to avoid breathlessness
This leads to weakening of the muscles and increased breathlessness, which leads to further avoidance
Cyclic process that increases inactivty and social isolation leading to the worsening of symptoms = Deconditioning
What is the aim of pulm. rehab?
Break the deconditioning cycle through a 6-12 week program of supervised exercise, unsupervised home exercise, nutritional advice and education
What are the advantages and disadvantages of long term O2 therapy?
When is it used?
Advantages:
Prevention of renal and cardiac damage due to extended periods of hypoxia
Disadvantages:
Loss of activity/independence
Must be 16+ hrs/day for survival benefit
When:
When pO2 consitently below 7.3kPa
Or below 8kPa with Cor Pulmonale
What are the surgical options for COPD?
Lung volume reduction:
Reduce hyperinflation by reducing lung volume
Lung transplant:
Option for younger patients
How might you manage an acute exacerbation of COPD?
Aim for Sats 88-92% with O2 therapy
Nubulised bronchodilators
Steroids (Oral or IV)
Antibiotics is infective (Raised CRP/WBCC or purulent sputum)
Consider IV Aminophylline
Repeat ABG, if no change consider Non-invasive ventilation or transfer to ITU for invasive ventilation
What is Non-invasive ventilation?
What are the contraindications?
Provision of ventilation support through mask or similar device
Contraindications:
Untreated pneumothorax
Impaired conscious level (Glasgow coma scale <8)
Facial injury
Life threatening hypoxia
Vomiting
Agitated
Give a brief description fothe organism that causes TB
Mycobacterium tuberculosis
Aerobic, acid and alcohol fast bacilli
How is TB transmitted?
Aerosolised droplets
Coughing, sneezing, talking and other resp manoeuvres create small particles called ‘droplet nuclei’ that disperse in the air
What happens in the first 6 weeks from contact and infection of TB occuring?
Alveolar macrophages phagocytose bacteria but cannot kill them (cell wall lipids block fusion of phagosomes and lysosomes)
Macrophages initiate development of cell mediated immunity which leads to the emergence of macrophages that can kill MTB bacteria
After cell mediated immunity is activated what is the further reaction to MTB bacteria?
Hint: Stop before explaining the active disease, or this would be a very long flashcard
A Ghon’s focus is formed
A ghon’s focus is a small, subpleural region of granulomatous inflammation
Appears as normal granuloma (Caseous necrosis surrounded by epitheloid macrophages, lymphocytes and Langerhan’s giant cells)
TB bacilli drain into surrounding (Hilar) lmph nodes
Surrounding nodes + Ghon’s focus are called ‘Ghon’s complex’
Normally heals in most patients, however before healing some TB bacilli enter the bloodstream (most likely via lymph drainage)
If it doesn’t heal primary TB infection results
TB bacteria seed other parts of the lung and other organs (In the case of other organs, can cause Miliary TB)
In this state, TB can remain inactive for years as latent TB to be reactivated as Secondary TB
What percentage of those infected with TB will develop active disease?
10%
5% Primary
5% Secondary
How is Latent TB tested for?
Outline how the test works and what happens if positive
Mantoux Tuberculin test
How it works:
Tuberculin (a complex mix of TB antigens extracted from TB) is injected transdermally
If an induration (raised, hardened patch of skin) persists at injection site after 48-72hrs indicates latent TB
Who are at greatest risk of developing active disease after latent infection?
IV drugs users
HIV cases
Those with Haematological malignancy
Chronic renal failure
Underweight
Immunocompromised
Describe the common active disease processes for Respiratory TB
Hint: Don’t go so far as to mention specific process that MAY occur, just the general stuff
Proliferation of TB bacteria in caseous centres leads to softening and liquefaction of necrotic tissue which may discharge into a bronchus
This results in a cavity formation, fibrous tissue forms around the periphery, containing it
Haemorrhage and Haemoptysis can result from extension of the caseous process into a blood vessel or Ramussen’s Aneurysm
Caseous material can spread through the bronchial tree to disseminate infection
Outline the pleural involvement in active TB
Pleural TB may occur
2 mechanisms for pleural involvement:
Hypersensitivity response in primary infection leads to acute pleuritic process (pleural effusion) with fever
Tuberculous Empyema (Pus) from a ruptured cavity spreads into the pleural space (has a tendency to burrow through chest wall)
What is meant by Tuberculous pneumonia?
Marked inflammatory exudate into alveoli and small airways
Appears similar on CXR to normal bacterial pneumonia
What are the symptoms of respiratory tuberculosis?
Commonly non specific
Include:
Tiredness and malaise
Weight loss and anorexia
Fever
Cough (most common)
Breathlessness (Pleural effusion)
Haemoptysis
What are the signs of respiratory TB?
Pallor
Fever
Evidence of weight loss
Often no external chest signs
Localised wheezing
Carvical nodes palpable
What is a Ramussen’s Aneurysm?
A pulmonary artery aneurysm adjacent or within a tuberculous cavity, It may lead to rupture and haemorrhage.
Haemoptysis results
What is lymph node tuberculosis?
Spread of TB bacteria to the lymph nodes, most commonly Cervical
Often painless
Results in swelling, can progress to marked inflammation and skin rupture
Swelling of the intra-thoracic nodes may collapse bronchi
What is osteo-arthritic TB?
A chronic inflammatory disease that affects the joints
Caused by the spread of TB bacteria to the joints
May present as:
Tuberculous spondylitis (most common)
Peripheral arthritis
Osteomyelitis
Poncet’s disease
Describe tuberculous spondylitis
Result of haematogenous spread of TB to the spinal vertebrae
Spreads to adjacent vertebrae via the vertebral disk space
Most common in upper lumbar and lower thoracic
Insidious onset over months
Paraplegia and quadraplegia result in 25% of cases
Leads to collapse of vertebral disks through caseation
Caseous lesions form on vertebral bodies
Vertebral narrowing and collapse may occur
Describe Miliary TB
Spread of Tb bacterium haematogenously leads to seeding of bacteria throughout the lungs and body, these can develop into active TB
Active TB process occur as normal but widely disseminated
May cause few rep symptoms
However Pericardial or pleural effusions and ascites may be present
What is Chronic ‘Cryptic’ Miliary TB?
Usually found in 60+
High mortality miliary TB with insidious onset
Syptoms include weight loss, lethargy and intermittent fever
Common to find at post-mortem
What investigations may be performed in a patient with suspected TB?
CXR
Sputum culture x3
Bronchoscopy
Gastric lavage
Biopsies
Detailed imaging (CT)
What radiological features might be seen on a CXR of a TB patient?
Pleural effusions
Multilobar shadowing
Cardiac enlargement (life threatening)
Multiple cavities (Very contagious)
Miliary shadowing (life threatening)
Flecks of calcification
How is tuberculosis diagnosed?
A combination of radiological and microbiologica findings paired with clinical presentation of the patient
Why is a multi-drug approach necessary for TB?
About one in a millin TB bacteria are spontaneously drug resistant
as there are 1x10^9 bacteria per typical TB cavitation a multidrug regimen is necessary to prevent the development of resistance
Outline a typical drug regimen for TB
Haw is this changed if there is CNS involvement (TB meningitis)?
Inital phase (2 months):
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Continuation phase (4 months):
Rifamipicin
Isoniazid
Continuation phase is 10 months if there is CNS involvement
What is the BCG vaccine?
How is it used?
The BCG vaccine consists of live, attenuated TB bacteria with greatly reduced virulence
Exposure to the antigens of the BCG vaccine confer resistance to TB as they are the same antigens
Used to protect high risk groups in the UK
Immunization of all school children was scrapped in 2005
Which ethnic group is at highest risk of TB in the UK?
The Asian and Asian British populations, commonly originating from India, Pakistan and Bangladesh
What is the relationship between HIV and TB?
HIV causes immunocompromisation by impairing cellular immunity (Decreasing CD4+ cell counts), this understandably raises the risk of infection.
Those with HIV are estimated 26-31x more likely to contract TB
Of 9 million TB cases worldwide in 2013, 1.1 million were in those with HIV
What is DOT (Directly observed therapy) and how and why is it used for TB treatment?
What:
Directly observed therapy is where drugs are administered under supervision by a medical professional
How:
Having the out-patient come in 3x per week to recieve treatment
Possible compulsory admission and dentention
Compulsory treatment not possible
Why:
Improves cure rates, TB rates, drug resistance and relapses
Often most useful in homeless, alcoholics, addicts, the seriously mentally ill and those with multi-drug resistances
