COPD Flashcards
What is COPD?
Common progressive disorder where abnormal inflammatory response to noxious particles/gases causes mainly irreversible airway obstruction. Includes chronic bronchitis and emphysema.
[OHCM, pts]
What is chronic bronchitis?
Clinically defined as a productive cough, most days for 3 months for 2 successive years. Symptoms improve when smoking ceases, and there is no excess mortality if lung function is normal. [ohcm]
What is the pathophysiology of bronchitis?
Inflammation causes hyperplasia and hypertrophy of the mucous glands. Excess mucus and wall thickening lead to airflow obstruction.
Give 3 risk factors for COPD.
Smoking (>90%) Age >35 Pollution Alpha-1 antitrypsin defficiency Men > women, although gap decreasing Low socioeconomic status
How does alpha-1 antitrypsin deficiency cause COPD?
A1ATD is an autosomal recessive disease where homozygotes develop severe panacinar emphysema which progresses to respiratory failure in their 40s/50s. Smoking exacerbates it by activating protease.
Describe the clinical features of bronchitis.
(Blue bloaters [medcomic]): Rhonchi (sounds like snoring), wheezing Cough with sputum Cyanosed, not breathless Peripheral oedema Cor pulmonale may occur
Why should you be careful when giving supplemental oxygen to someone with bronchitis?
Their respiratory centres and relatively insensitive to CO2, their respiratory drive relies on hypoxia. Giving them oxygen can therefore deplete their respiratory drive so they stop breathing.
[ohcm, pts]
How is the diagnosis of chronic bronchitis made?
Clinically: Cough with sputum most days for 3 months of 2 successive years.
What causes rhonchi?
Rhonchi are low-pitched, rattling lung sounds caused by secretions (eg mucus) and obstruction (eg inflammation) in the bronchi. They usually clear after coughing.
What investigations would you do for chronic bronchitis and what would they show?
Alveolar ventilation - decreased because thicker diffusion barrier
PaO2 low, PaCO2 high - decreased alveolar ventilation
Give 3 differential diagnoses for COPD.
Asthma - breathlessness, younger age of onset.
Pulmonary embolism
Emphysema - pink puffers
Bronchitis - blue bloaters
Give 3 symptoms of COPD.
Cough, sputum, dyspnoea, wheeze, fatigue, low mood.
Give 3 signs of COPD.
Tachypnoea
Use of accessory muscles of respiration
Ankle swelling due to resulting RHF
How is emphysema diagnosed?
Histologically:
Enlarged air spaces distal to terminal bronchioles, with destruction of alveolar walls.
Often visualised on CT.
Describe the presentation of emphysema.
‘Pink puffers’ [medcomic]:
severe dyspnoea, not cyanosed,
quiet chest (no rhonchi)
Barrel chest
What would alveolar ventilation, PaO2 and PaCO2 show in emphysema?
Alveolar ventilation increased because there is increased lung volume (fewer acini).
PaO2 is normal and PaCO2 is normal/low.
What investigations are done to diagnose COPD?
Chest X ray
Spirometry
ABG
ECG
What would you see on CXR for COPD?
Large central pulmonary arteries
Flattened diaphragm
Emphysema: hypodense bullae, hyperinflation. [ohcm, pts]
What would you see on spirometry for COPD?
Obstructive air air trapping: FEV1 <80% predicted; FVC normal/low; overall effect is: FEV1:FVC <70% Increased TLC and RV Decreased DLCO in emphysema. [ohcm] reduced PEFR [pts]
What would ABGs show for COPD?
Decreased PaO2.[ohcm]
Raised HCO3 shows compensation due to a chronic CO2 retention.
Hypoxia with low PaCO2 =high resp. drive, pink puffer
Hypoxia with high PaCO2 = low resp. drive, blue bloater
[pts]
What may be seen on ECG in COPD?
Cor pulmonale: right atrial and ventricular hypertrophy.
What may be seen on CT for COPD?
Bronchial wall thickening (bronchitis), scarring, airspace enlargement (emphysema).
Describe the pathophysiology of emphysema.
Many types, most common in centrolobular, affecting the proximal acinus, asso with smoking. May also see panacinar pattern in lower lobes. Loss of elasticity in alveolar walls causes them to burst, reducing surface area for gas exchange.
What are the aims of treatment for COPD?
Reduce symptoms - improve exercise tolerance, relieve symptoms
Reduce risk - prevent exacerbations, mortality and progression
Describe the non-pharmacological management of COPD.
Smoking cessation
Avoid infections and increase tolerance with exercise
Diet advice, supplements
What is first-line treatment for advanced COPD?
SABA (salbutamol) / SAMA (ipratropium)
What is the treatment for advanced COPD if SAMA/SABAs fail?
LAMA (tiotropium)
If FEV1 >50%, LABA (salmeterol)
If FEV1 <50%, LABA plus ICS (beclomethasone) in combined inhaler.
Salmeterol - class, mechanism?
Long-acting beta(-adrenoreceptor) agonist. Cause calcium channels to close and stimulates beta-2 receptors in bronchial smooth muscle, causing relaxation of muscle and therefore dilation of the airways.
Give a major side-effect and CI of salmeterol.
Muscle relaxation causes tachycardia and hypertension.
Do not use with beta-blockers as this will diminish the effect.
Ipratropium - class, mechanism?
Long-acting muscarinic antagonist. Blocks activity of muscarinic acetylcholine receptors (the ones which respond to muscarine), causing bronchial smooth muscle relaxation.
Give a SE and interaction of ipratropium.
Dry mouth, sedation
Interaction with other anticholinergics eg tricyclic antidepressants.
Give 3 pathogens which exacerbate COPD.
Viral upper RTIs, tracheobronchial tree infections [lecture 12.12.17] Strep pneumoniae Haemophilus influenzae Moraxella catarrhalis [pts, 2011 SAQ]
Describe the first-line management of a COPD exacerbation.
SABA (salbutamol) +/- SAMA (ipratropium).
Systemic corticosteroids and antibiotics can also help.
Give 3 investigations for a COPD exacerbation and why you would do them.
ABG - respiratory failure? PaO2<8kPa.
CXR - exclude alternative diagnoses
ECG - aid in diagnosis of co-existing cardiac problems.
FBC - identify polycythaemia, anaemia or bleeding.
Sputum - if purulent, begin empirical antibiotics.
U&E - detect electrolyte imbalance, diabetes, poor nutrition.
What is the target saturation of oxygen therapy in COPD?
88-92%.
What are the effects of systemic corticosteroids in COPD exacerbations? Give an example of a CS used.
Prednisolone
- Shortens recovery time + hospital stay
- Improves lung function (FEV1) and hypoxemia (PaO2)
- reduces risk of early relapse
What indicates need for antibiotics in COPD patients?
- Increased dyspnoea+ sputum volume+sputum purulence OR
2. Requiring mechanical ventilation.
What indicates need for hospital admission in COPD patients?
Marked increase in severity of symptoms Severe underlying COPD Onset of new physical signs Frequent exacerbations Older age
What would high PaCO2 and pH <7.36 indicate in someone with COPD?
Acute respiratory acidosis. Exacerbation of COPD
