COPD Flashcards
What is the definition of COPD?
Broad term for a few obstructive airway disorders:
Chronic bronchitis
Emphysema
Airflow obstruction is defined as a reduced FEV1/FVC ratio = <0.7
Airflow obstruction is present because of a combination of airway and parenchymal damage
What is the epidemiology of COPD?
1.5 million with 23,000 mortality/year in the UK
3rd leading cause of death by 2020 and increasing
More common in men but rising in women
Low socioeconomic status and low birth weight are predisposing factors
What is the aetiology of COPD?
Smoking is the main cause – 90-98% of all cases
Most commonly seen in ex smokers >35 yrs old
Unlikely to develop in someone with less than 10 pack years
Other causes are occupational:
Coal mining
Asbestos exposure
Genetic factors:
Alpha1-antitrypsin deficiency causes emphysema
Age related too – onset in 50s-60s
What is the pathophysiology of emphysema?
Destruction of lung parenchyma – alveoli and respiratory bronchioles
Confluent areas of destruction may cause macroscopic bullae (large blisters containing serous fluid)
Can be named according to location of damage
What is the pathophysiology of bronchitis?
Submucosal bronchial gland enlargement and goblet cell metaplasia and mucous hypersecretion
Inflamed bronchial glands
Airway epithelial squamous metaplasia
Cilliary dysfunction
Hypertrophy of smooth muscle and connective tissue
What are some other general features of the pathology of COPD?
Involvement of smaller airways is key:
- Loss of elasticity means the airways aren’t splinted open and so with increased intrathoracic pressure during expiration, they may collapse - limiting airflow
Pulmonary vasculature:
- Thickening and endothelial cell destruction
- Hypertrophy of vascular smooth muscle and collagen deposition lead to reduction in functioning of vessels
- Pulmonary vasoconstriction due to hypoxia - pulmonary artery pressure rises – pulmonary hypertension - right heart failure
Inflammatory profile:
- Different to asthma
- Asthma – CD4 lymphocyte, eosinophils
- COPD – CD8 lymphocytes, macrophages, neutrophils (may also have eosinophils)
How does COPD present?
SOB
Cough - often productive sputum (a spectrum of colours from mucoid/white to purulent/green, worse with infection, possible blood if Ca)
Wheeze
Poor expansion
Cyanosis
Use of respiratory muscles for respiration
Signs of CO2 retention i.e. confusion, flap
Nicotine/tar stained hands
Barrel chest
Pulmonary heart disease (cor pulmonale)
Asthmatic features:
Atopy, early onset symptoms, minimal smoking history, eosinophilia, bronchodilator reversibility
What is the MRC breathlessness scale?
Grading of breathlessness, used to assess functioning:
Grade 1 = not troubled by SOB, only on strenuous exercise
Grade 2 = SOB when hurrying on level or walking up slight incline
Grade 3 = walks slower than most on level ground, stops after a mile or so or after 15 mins walking at own pace
Grade 4 = stops for breath after 100yrds or a few mins on level ground
Grade 5 = too breathless to leave house, or breathless when undressing
How do you investigate COPD? What are the key findings?
Diagnosis = clinical judgement based on:
- History
- Physical examination
- Confirmation of airway obstruction using spirometry
- COPD assessment test (CAT) – questionnaire
Spirometry:
- FVC<80% predicted
- Low FEV1
- FEV1/FVC <0.7
- Increased residual volume
ABG:
- Lower PaO2 - 88-92% are typical targets
- Poor ventilation may also give high CO2 (T2 resp. failure)
- Poor V/Q mismatch
- Always note what FiO2 is (air? 2L? more?)
Other:
- CXR, CT scan - possible: hyperinflation, flat hemidiaphragms, large pulmonary arteries, decreased peripheral vascular markings; pneumothoracies? infection? Ca?
- ECG - right atrial and ventricular hypertrophy suggestive of cor pulomnale – large P waves
- Blood α1 antitrypsin - possible deficiency (neutrophil enzyme elastase is then free to break down elastin in lungs, reducing elasticity and leading to COPD)
What are non-pharmacological managements for COPD?
Smoking cessation – the best thing to do, at any point in the illness
Encourage exercise at own level - walking
Nutritional support - either weight loss or gain might be required
Physiotherapy - breathing and coughing techniques
Possible need for OT/psychoT.
Recognising signs of exacerbations - hospital plan for when this is the case
Vaccination – pneumococcal and influenza - to prevent any respiratory infections
Follow up at least yearly, more regularly with severe disease +/- specialists
Fitness to fly assessments:
- Enquiring whether the person is able to walk for 50 metres at a normal pace, or climb one flight of stairs, without significant breathlessness - If so, it is likely that the person will tolerate the normal aircraft environment
- Also hypoxic challenge test
- More guidelines re. specific questions pre-flying
Pulmonary rehabilitation
What is pulmonary rehabilitation for COPD?
- Given when MRC score 3-5
- 6-12 wks, 2-3 times/wk
- Aerobic and resistance training
- Education
- Nutritional support
- Psychological support
- Repeat annually or if circumstances change
- Improves - exercise capacity, QoL, SOB, Fewer hospitalisations
Not for patients that cannot walk or have unstable angina or a recent MI
What is the stepwise management for COPD?
1) Inhaled bronchodilators:
- For SOB + exercise limitation
- SABA - salbutamol - PRN OR
- SAMA - ipratropium bromide PRN
- Need to ensure appropriate delivery system (coordination, dexterity etc)
2a) If no improvement WITHOUT features of asthma or steroid responsiveness:
- LABA - salmeterol AND
- LAMA - tiotropium (often come as combined inhalers)
- Discontinue SAMA
- If no improvement, add 3/12 trial ICS and reassess for stopping/continuation
2b) If no improvement WITH features of asthma/steroid responsiveness:
- LABA + ICS (often come as combined inhalers)
- (+/- LAMA if still not improving = triple therapy; discontinue SAMA)
What other treatments can be prescribed by a specialist for people with COPD who require more than inhalers?
Home nebulisers:
- O2 vs air driven - if hypercapnic = air driven
Oral corticosteroids:
- Remember osteoporosis prophylaxis
Oral theophylline:
- For those who have not benefitted from inhalers or who cannot use inhaled therapy
- Plasma level monitoring and dose adjustment required
- Reduce dose if macrolides or fluoroquinolones prescribed for an exacerbation
Oral mucolytic therapy:
- Only if chronic productive cough
- PO N-acetyl cystine
Oral prophylactic Abx:
- Strict criteria, including >3 exacerbations requiring steroids in last year incl. 1 hospital admission
- Macrolide e.g. azithromycin 500mg 3x/wk
- Need ECG (QTc), LFTs, sputum MC+S, CT
What is long term oxygen oxygen therapy and the indications for it?
Long term oxygen therapy (LTOT):
2L via nasal cannula for at least 15hrs/day in really extreme cases
DO NOT START WITHOUT SPECIALIST SUPPORT:
May cause respiratory depression due to reduced hypercapnic drive for respiration
Indications:
- Oxygen saturation less than or equal to 92% breathing air
- Very severe airflow obstruction - FEV1 < 30% predicted
- Cyanosis
- Secondary polycythaemia
- Peripheral oedema
- Raised jugular venous pressure
Need counselling on fire/explosive risk - NO SMOKING
How do you grade acute exacerbations of COPD?
Acute exacerbation:
- Worsening breathlessness
- Increased sputum volume and purulence
- (new) Cough
- Wheeze
- Fever
- Upper respiratory tract infection in the past 5 days
- Increased respiratory rate or heart rate increase 20% above baseline
Acute severe exacerbation:
- Marked breathlessness and tachypnoea
- Pursed-lip breathing and/or use of accessory muscles at rest
- New-onset cyanosis (O2 <90% on oximetry) or peripheral oedema
- Acute confusion or drowsiness
- Marked reduction in activities of daily living
Need a full clinical assessment:
- Vital signs, resp. examination, coping at home etc
- Consider other possible Dx
- Consider the need for hospital admission
