COPD Flashcards
COPD definition
Progressive + Irreversible obstructive airway disease - combination of emphysema and chronic bronchitis
- most commonly caused by smoking
Emphysema defintion
Loss of alveolar integrity due to an imbalance between proteases and protease inhibitors (e.g. alpha-1 antitrypsin) triggered by chronic inflammation, such as smoking = leads to elastin breakdown by neutrophil elastase.
Chronic Bronchitis
Hypertrophy and hyperplasia of mucous glands (mucus protective vs damage)
Chronic inflammation cells infiltrate bronchi - luminal narrowing
MUCUS HYPERSECRETION, CILIARY DYSFUNCTION, NARROWED LUMEN (therefore increased risk of infection and airway trapping)
Involves mucus secretion secondary to ciliary dysfunction and increased goblet number and size → lung parenchymal destruction → impaired gas exchange
Cough for 3+ months over 2+ years
Epidemiology
Over 45
Risk factors
- Tobacco smoking (MC)
- Air pollution
- Indoor burning of biomass fuels
- Occupational exposure: such as dust, cadmium (in smelting), coal, cotton, cement and grain
- Alpha-1 antitrypsin deficiency: younger patients present with features of COPD
Symptoms
Wheeze
Productive cough
Dyspnoea
* no clubbing - unusual to cause haemoptysis or chest pain = these symptoms should be investigated for a different cause *
Signs
Tachypnoea
Barrel chest
Hyper-resonance on percussion
Quiet breath sounds and wheeze
Tar staining of fingers with peripheral cyanosis
Evidence of an exacerbation:
- Significant dyspnoea, wheeze and cough
- Coarse crepitations
- Pyrexia
Evidence of cor pulmonale = right-sided heart failure due to severe (COPD)
- Peripheral oedema.
- Raised jugular venous pressure.
- Systolic parasternal heave.
- A loud pulmonary second heart sound (over the second left intercostal space).
- Hepatomegaly.
Investigations
FIRST LINE + GOLD STANDARD = Spirometry
- FEV1/FVC < 0.70 and lack of reversibility
- FVC (max air inhaled in one breath) = low
- FEV-1 (first second of air breathed out) = low > FVC
- TLC (total lung capacity) = increased due to air trapping
*. Bronchodilator reversibility not recommended *
Fractional expired NO increased (indicates lung damage)
CXR =
- Flattened diaphragm
- Hyperinflation
- Bullae: if large may mimic pneumothorax
- Exclude lung cancer
FBC =
- COPD causes chronic hypoxia which may result in secondary polycythaemia
ABG
- low PaO2 + high PaCO2
Genetic testing for A1AT def
ABG
- mat show T2RF
DlCO (diffusing capacity of CO across lung)
- Low in COPD
- Normal in ASTHMA
There is V/Q mismatch as pulmonary arterioles vasoconstriction where there is poor ventilation at alveoli
Bronchodilator dilator vs irreversible
< 12% increased FEV1= COPD
> 12% increased FEV1 = ASTHMA
Typical patient
Older patient who is a long term smoker, chronic cough with purulent sputum and a wheeze
- increased risk of infection due to mucus hypersecretion + stasis
- exception - A1AT
- constant Dyspnoea (not episodic)
GOLD classification
Severity of airflow obstruction
1) Post-bronchodilator FEV1/FVC
2) FEV1 (% of predicted)
Stage 1: Mild*
1) <0.70
2) ≥80%
Stage 2: Moderate
1) <0.70
2) 50-79%
Stage 3: Severe
1) <0.70
2) 30-49%
Stage 4: Very severe
1) <0.70
2) <30%
MRC Dyspnoea scale
Grade 1 = Breathless on strenuous exercise
Grade 2 = Breathless on walking up a hill
Grade 3 = Breathless that shows on walking on flat
Grade 4 = Stop to catch their breathe after walking 100 metres on flat
Grade 5 = Unable to leave the house due to breathlessness
Management
Stop smoking, resp exercises
Pneumococcal + annual flu vaccines
FIRST LINE MEDICATION = SABA (salbutamol)
Criteria to determine whether a patient has asthmatic/steroid responsive features
- Any previous diagnosis of asthma or atopy
- higher blood eosinophil count
- substantial variation in FEV1 overtime (atleast 400ml)
- substantial diurnal variation in peak expiratory flow (atleast 20%)
Second line if patients DO NOT have asthmatic features or features suggestive of steroid responsiveness
SABA (salbutamol) +
LABA (formoterol, salmeterol) +
LAMA (tiotropium)
Second line if patients DO have asthmatic features or features suggestive of steroid responsiveness
SABA (salbutamol) +
LABA (formoterol, salmeterol)
ICS (budesonide)
Third line treatment
SABA (salbutamol) +
LABA (salmeterol) +
LAMA (tiotropium) +
ICS (budesonide)
Other management
Long term O2 therapy
- if sats < 92% on room air
- cyanosis
- polycythaemia
- peripheral oedema
- if FEV1 < 30% of predicted
- do not smoke with oxygen therapy = FIRE RISK
Oral Theophylline = bronchodilation + reduce response to stimuli
Oral mucolytic therapy (carbocisteine)
- breakdown sputum
Loop diuretics = furosemide = manage cor pulmonale
How do SABAs work?
Activate beta 2 receptors (which are normally activated by NAD) = Bronchodilation = SALBUTAMOL
How do LABAs work?
Same as above but longer duration of action = SALMETEROL
How do SAMAs work?
Binds to M3 muscarinic receptors which prevent Ach from binding so prevent bronchoconstriction = IPATROPIUM BROMIDE
How do LAMAs work?
same as above but longer = TIOTROPIUM
Exacerbations of COPD
Triggered by bacterial/viral infections
Most common bacterial organisms:
- Haemophilus influenzae (MC)
- Streptococcus pneumoniae
- Moraxella catarrhalis
Symptoms of exacerbations
Increase in dyspnoea
Increase in sputum suggestive of infective cause
May be hypoxic + have acute confusion
Investigations for exacerbations
ABG:
- Higher CO2 = respiratory acidosis
- Higher HCO3 = compensation by the kidneys
FBC:
- raised WCC due to infection
- sputum culture
Types of respiratory failure
T1RF: Normal pCO2 + low pO2
- Fibrosis causes lungs to fail to fill properly.
- Tx = continuous +ve airway pressure
T2RF: Raised pCO2 + low pO2
- Obstruction causes lungs to fail to remove CO2 properly
- bi positive airway pressure
BOTH: Low pO2 indicates hypoxia + respiratory failure
Exacerbation treatment
- bronchodilators through nebuliser (salbutamol + ipatropium bromide) + oxygen
- oral prednisolone or IV hydrocortisone
- antibiotics (amoxicillin)
- physio (clear sputum)
Severe treatment
- IV aminophylline
- non-invasive ventilation
- intubation + ventilation with admission to ICU
- doxapram = respiritory stimulant when NIV or intubation not appropriate
Differentials
Asthma
Bronchiectasis
Bronchiolitis
Heart Failure
Complications
Cor pulmonale
T1 or 2 resp failure
COPD exacerbations
Secondary polycythaemia
Infection
Depression
Lung cancer
