COPD Flashcards
What is COPD - Chronic Obstructive Pulmonary Disease?
COPD is a progressive disorder characterised by airway obstruction with little or no reversibility. It is the obstruction that causes the disabling symptoms
Two conditions come under COPD:
- Chronic Bronchitis
- Emphysema
How is Chronic Bronchitis defined?
- Chronic Bronchitis involves productive cough and sputum for 3 consecutive months over 2 years
- Also known as Blue Bloaters
What is Emphysema?
- Emphysema is defined radiologically as the permanent dilation of the airways distal to the terminal bronchiole
What are the main clinical features found in those with COPD?
- Increased cough and sputum production
- Breathlessness on exertion
- In advanced disease, breathlessness on minimal exertion or rest
What are the main causes of death in COPD?
- Bronchopneumonia
- Respiratory failure
- Heart Failure
What is the pathophysiology of COPD?
Smoking damages the airway through the respiratory tract, but its affects vary depending on the exact location
BRONCHI - hyperplasia of mucus glands and goblet cells results in increased sputum production
SMALL AIRWAYS - chronic inflammation, leading to fibrosis and eventual stenosis of airway
RESPIRATORY BRONCHIOLES - destruction of walls through loss of elastin, leading to permanent dilation hence emphysema
In emphysema, macrophages release elastase which acts on elastin within alveolar walls - causing breakdown. There is therefore less trapping upon expiration so air trapping occurs
What is the protease/anti-protease hypothesis?
- Smoking increases number of neutrophils
- These neutrophils release elastase
- Smoking also inhibit the lungs’ natural protease inhibitor - a1 anti-trypsin
What can a congenital deficiency in a1 anti-trypsin cause?
Liver cirrhosis and hepatocellular carcinoma in adults
In lungs, panacinar emphysema in the lower lobes
=> More on a1 antitrypsin deficiency:
- Inherited in an autosomal recessive fashion
- Gene for protease is found on chromosome 14
- Manifests in patients with the PiZZ genotype
What are the risk factors of COPD?
- Age
- Genes
- Long term smoking
What are the main causes of COPD?
- Smoking
- Air pollution
- Occupational exposure
- Intolerance of proteases and anti-proteases
What is the formula for calculating pack years?
Pack years = no. of packs per day x years of smoking
What is the role of spirometry in COPD?
In emphysema:
- Increased TLC
- Increased Residual volume
- Decreased diffusing capacity for carbon monoxide
COPD is categorised in terms of severity based on post bronchodilator FEV1 predicted value
> 80% - Stage 1 Mild
50-79% - Stage 2 Moderate
30-49% - Stage 3 Severe
<30% - Stage 4 Very severe
What are the investigations carried out in suspected COPD?
=> CXR
- Hypeinflation
- Flat hemidiaphragm
- Large central pulmonary arteries
=> Blood
- Raised haemocrit
=> ABG
Decreased PaO2 accompanied with possible hypercapnia
=> CT
- Bronchial wall thickening
- Scarring
- Air space enlargement
=> Spirometry
- Obstructive picture
What is the emergency management of the acute exacerbation of COPD?
First step is to provide nebulised bronchodilators - SALBUTAMOL 5mg/4h (SABA) + IPATROPIUM 500mg/6h (LAMA). Then carry out investigations - CXR and ABG
Controlled oxygen therapy if SaO2 < 85% or PaO2 < 7.3 kPa. Oxygen levels adjusted depending on ABG
Administer steroids. IV HYDROCORTISONE 200mg and PO PREDINISOLONE 30mg (ICS)
Give antibiotics if there is evidence of infection
Physiotherapy to aid sputum clearance
If there is no response to bronchodilators or steroids, give IV AMINOPHYLLINE
If there is still no response:
- Consider non invasive positive pressure ventilation
- Consider respiratory drug stimulant
What is the management of more stable and advanced COPD?
General management involves:
- smoking cessation
- influenza vaccine
- one off pneumococcal vaccine
- pulmonary rehabiliation
Bronchodilator therapy:
- SABA or SAMA is first line treatment
- If patient remains breathless or has exacerbations next step is to determine whether they have any asthmatic features triggered by steroids
=> Features suggesting asthmatic steroid responsiveness:
- secure diagnosis of asthma
- high eosinophil count
- substantial variation in FEV1
- substantial diurnal variation in PEF
=> If there are no asthmatic features triggered by steroids:
- Add LABA + LAMA
- If already taking SAMA, discontinue and take SABA instead
=> If there are asthmatic features triggered by steroids:
- LABA + ICS
- If still breathless then triple therapy: LABA + LAMA + ICS
How is infective exacerbation of COPD and pneumonia differentiated?
=> Based on:
- Underlying COPD
- Site of infection
- CXR changes
- Most common causes
UNDERLYING COPD:
- In infective exacerbation => always
- In pneumonia => sometimes
SITE OF INFECTION:
- In infective exacerbation => airways
- In pneumonia => alveoli
CXR CHANGES:
- In infective exacerbation => clear lung fields
- In pneumonia => consolidation
MOST COMMON CAUSES:
=> In infective exacerbation: H. Influenza, M. Catarrhalis, S. Pneumonia, viruses
=> In Pneumonia: S. Pneumonia, H. Influenza, viruses, atypical organisms
What is the criteria for onward referral in stable COPD?
- Diagnosis uncertain
- Onset Cor Pulmonale
- Bullous lung disease
- History shows < 10 pack years
- Frequent infections
- Symptoms disproportionate to Lung Function Tests
What is Cor Pulmonale?
Abnormal enlargement of the right side of the hart due to disease of lungs or pulmonary blood vessels
(Right Heart Failure due to lung pathology)
What are the drugs used for smoking cessation?
- Varenicline => PO selective nicotine receptor partial agonist
- Buproprion => only considered if varenicline fails. NA and Dopamine reuptake inhibitor
Contraindicated in pregnancy, history of epilepsy
- Target stop date
- 2 weeks of NRT
- Followed by 3-4 weeks of Varenicline or Buproprion
- If unsuccessful do not offer a repeat prescription in the next 6 months
What is the MOA of THEOPHYLLINE?
PDE inhibitor. It relaxes smooth muscles of the bronchial airways and reduces airway responsiveness to histamines, methacoline, adenosine and allergens
What are the complications of COPD?
- Acute exacerbations
- Infections
- Type 2 Respiratory failure
- Cor Pulmonale
- Pneumothorax
- Lung carcinoma
What is the differential diagnosis of COPD?
- Asthma
- Congestive Heart Failure
- Upper airway obstruction
- GORD
- Lung cancers
- TB
What are the results of Lung Function Tests in obstructive disease?
FEV1
FVC
FEV1/FVC
Give examples of obstructive lung diseases
FEV1 - reduced (<80% predicted)
FVC - reduced or low
FEV1/FVC - reduced (<70% predicted)
Asthma
COPD
Bronchiectasis - permanent dilation of the airways secondary to chronic inflammation or infection
Bronchiolitis Oliterans
What are the results of Lung Function Tests in restrictive disease?
FEV1
FVC
FEV1/FVC
Give examples of restrictive lung diseases
FEV1 - reduced
FVC - reduced
FEV1/FVC - normal
Pulmonary Fibrosis Asbestosis Sarcoidosis - multi-system disorder of unknown aetiology characterised by non-caseating granulomas ARDS IRDS Neuromuscular disorders Severe obesity Kyphoscoliosis
What are the two types of non-invasive positive pressure ventilaitons?
- Bilevel Positive pressure Ventilation
- Continuos Positive Pressure Ventilation
=> Bilevel Positive Pressure Ventilation:
- Used in acute type 2 respiratory failure
- Stenting alveoli to increase surface area available for gas exchange
=> Continuos Positive Pressure Ventilation:
- Not as effective in COPD
- Used in cases of Type 1 respiratory failure especially pulmonary oedema
Non-invasive ventilation methods are used when the pH is between 7.25-7.35. For pH lower than 7.25, invasive ventilation is required
How can a1-antitrypsin deficiency be diagnosed prenatally?
- Aminocentesis
- Chronic villus sampling
What is the pathophysiology of a1-antitrypsin deficiency?
- Leads to accumulation of mutant Z protein within hepatocytes
- This accumulation triggers apoptosis or rapid proliferation of hepatocytes
What is transfer factor?
- Describes the rate at which gas will transfer from the alveoli into the blood
- Results may be given as total gas transfer (TLCO) or transfer coefficient (KCO)
What are the causes of a raised TLCO?
- Asthma
- Pulmonary haemorrhage
- Left to right cardiac shunts
- Polycythemia
- Hyperkinetic states
- Male gender
What are the causes of a low TLCO?
- Pulmonary Fibrosis
- Pneumonia
- Pulmonary Emboli
- Pulmonary oedema
- Emphysema
- Anaemia
- Low CO
What is the best intervention to increase survival for those with COPD?
Smoking cessation
=> After smoking cessation: Long Term Oxygen Therapy
=> LTOT considered in those with PaO2 < 7.3 kPa or in those with 7.3 < PaO2 < 8 AND 1 of following:
- Secondary Polycythaemia
- Nocturnal hypoxemia
- Peripheral oedema
- Pulmonary hypertension
When should oral antibiotic prophylaxis be considered?
=> Azithromycin prophylaxis considered in selected patients that match following criteria:
- Do not smoke
- Optimised non-pharmacological therapy, inhaled therapies, relevant vaccinations and pulmonary rehabilitation but continue to have:
- frequent exacerbations with sputum production
- prolonged exacerbations with sputum production
- exacerbations resulting in hospitalisation
Medications given for smoking cessation?
- NRT
- Varenicline
- Buproprion
What is the MOA of Varenicline and what are its adverse affects and contraindications?
=> MOA:
- Nicotine receptor partial agonist
- Recommended course of treatment is 12 weeks
=> Common adverse affects:
- Nausea and vomiting
- Headaches
- Insomnia
- Abnormal dreams
=> Contraindications:
- Pregnancy
- Breastfeeding
- Should be given with caution to those with depression and risk of suicidal behaviour
What is the MOA of Buproprion and what are its adverse affects and contraindications?
=> MOA:
- NA and dopamine reuptake inhibitor
=> Adverse affects:
- Seizures
=> Contraindications:
- Pregnancy
- Seizures
- Breastfeeding
- Eating disorders
