Week 6 - COPD, LRTI, Pneumonia Flashcards
What are the main causes of COPD?
- Smoking (most)
- Alpha-1-antitrypsin deficiency
- Occupational exposure
- – E.g. coal dust
- Pollution
Describe COPD + its causes of airflow obstruction
Characterised by airflow obstruction. The airflow obstruction is usually progressive, not fully reversible and does not change markedly over several months
- An umbrella term encompassing emphysema and chronic bronchitis
- Emphysema = a pathological process in which there is destruction of the terminal bronchioles and distal airspaces
— Leads to loss of the alveolar surface area and therefore the impairment of gas exchange
— Often progresses to the development of larger redundant airspaces within the lung, called bullae
— Causes the destruction of the supporting tissue surrounding the small airways, which therefore tend to close during expiration when the pressure outside the airways rises
• Results in airflow obstruction, particularly affecting the small airways
— Loss of elastic tissue in the lung causes the lungs to hyperinflate because the lungs are unable to resist the natural tendency of the rib cage to expand outwards
- Chronic bronchitis = chronic mucus hypersecretion
— Caused by inflammation in the large airways (usually due to cigarette smoke)
— Results in a chronic productive cough and frequent respiratory infections
• Frequently persists even after smoking has stopped
— Part of an inflammatory process, usually triggered by smoking, that results in airflow obstruction due to remodelling and narrowing of the airways
What are the symptoms and signs of COPD?
Symptoms:
- Cough and sputum production
- Many patients do not present until they are breathless
— Often progressive and associated
- Exacerbations are associated with increased breathlessness and an increase in cough and sputum production
— May be infective
Signs
- Purse lip breathing
— Increases the pressure within the airways
— Causes a reduction or delay in the closure of these airways
- Tachypnoea
- Using accessory muscles
- Hyperinflation
— Diaphragm and accessory muscles have to work much harder to ventilate the lungs, so major cause of breathlessness
- Wheeze or quiet breath sounds on auscultation
- In more advanced cases:
— Cyanosis and CO2 retention
— Right heart failure (cor pulmonale) with oedema
How can you measure airflow obstruction?
- Spirometry
— Non-invasive and reproducible technique
— Forced expiratory manoeuvre
• Involves blowing out as hard and fast as possible into a sealed tube
• The volume of expired air is plotted against time - In COPD there is limitation to the flow of air during expiration and so the volume of air expired in the first second (FEV1) is reduced
— Further compounded by airway collapse on expiration - Confirms diagnosis of COPD
- Gives a measure of the severity of airflow obstruction
How can you diagnose COPD?
- Relies on the combination of suggestive symptoms and signs together with the presence of airflow obstruction on spirometry
- Features suggestive of COPD:
- – Smoker or ex-smoker
- – Older patient (>40 years old) and onset of symptoms in later life
- – Chronic productive cough
- – Breathlessness that is usually persistent and progressive
What other investigations could you use in COPD?
- Chest x-ray
- – To exclude other diagnoses
- High-resolution computer tomography (HRCT) scanning
- – Provides a detailed assessment of the degree of macroscopic alveolar destruction in emphysema
- – May be helpful if surgical intervention is contemplated or the diagnosis is in doubt
- Arterial blood gas to assess for respiratory failure
- Alpha-1 antitrypsin blood test for younger patients
How can you manage stable COPD?
- Smoking cessation
- Pulmonary rehabilitation
- Bronchodilators
— Anticholinergics or β2-agonist - Antimuscarinics
- Steroids
- Mucolytics
- Methylxanthines
- Diet
- Supportive
- Long term oxygen therapy
- Lung volume reduction
- Surgical options
— Lung volume reduction
• The reduction of hyperinflation is the principal aim of this
— Lung transplant
How do you manage an acute exacerbation of COPD?
- Monitoring for hypoxia and hypercapnia
- – Using pulse oximetry and ABG analysis
- Appropriate antibiotics (if an infectious exacerbation)
- – Should cover Haemophillus influenzae and Streptococcus pneumoniae
- Nebulised bronchodilators
- Oral steroids
- 24% or 28% oxygen therapy while keeping under review for CO2 retention
- Consider non-invasive ventilation for worsening type 2 respiratory failure
What are some complications of COPD?
- Recurrent pneumonia
- Pneumothorax
- Respiratory failure
- Cor pulmonale (right heart failure)
What are some side effects of long term use of steroids?
- Thin skin
- Bruising
- Cataracts
- Adrenal insufficiency
- Osteoporosis
- Diabetes
- Increased weight (fluid retention)
- Mental disturbance
- GI symptoms
- Proximal myopathy
What are some adverse effects of anticholinergics?
- Dry mouth and cough
- Sore throat
- Pharyngitis
- Upper respiratory tract infection
- Bitter taste
- Nausea
- Supraventricular tachycardia
- Atrial fibrillation
- Urinary difficulty
- Urinary retention
- Constipation
What are some adverse effects of β2-agonists?
- Tachycardia
- Tremor
- Anxiety
- Palpitations
- Hypokalaemia
Describe the use of pulmonary rehabilitation in COPD?
- Many patients with COPD avoid exercise and physical activity because of breathlessness
- This may lead to a vicious cycle of increasing social isolation and inactivity, leading to worsening of symptoms
- Aims to reduce this cycle
- – Supervised exercise
- – Unsupervised home exercise
- – Nutritional advice
- – Disease education
Describe the use of methylxanthines in COPD
- Mode of action:
— Bronchodilation
— Increase respiratory drive
— Increase strength of respiratory muscles
— Anti-inflammatory effects - Mechanism of action
— Inhibition of phosphodiesterases
• PDEs break down cAMP so inhibition leads to an increase in cAMP leading to bronchodilation - Toxicity
— Tachycardia/supraventricular tachycardia
— Nausea
— Seizures
Describe the use of long term oxygen therapy in COPD
- If appropriate
- Extended periods of hypoxia cause renal and cardiac damage, but can be prevented by LTOT
- Continuous oxygen therapy for most of the day
- – At least 16 hours/day for a survival benefit
- Offered if pO2 is consistently below 7.3 kPa or below 8 kPa with cor pulmonale
- Patients must be non-smokers and not retain high levels of CO2
- O2 needs should be balanced with loss of independence and reduced activity which may occur
