Chronic Obstructive Pulmonary Disease

• Chronic obstructive pulmonary disease (COPD) involves a long-term, progressive condition involving airway obstruction, chronic bronchitis, and emphysema. It is almost always the result of smoking and is largely preventable. While it is not reversible, it is treatable.
• Damage to the lung tissues obstructs the flow of air through the airways.
• Chronic bronchitis


  Refers to long-term symptoms of a cough and sputum production due to inflammation in the bronchi
• Emphysema


  Involves damage and dilatation of the alveolar sacs and alveoli, decreasing the surface area for gas exchange
• Unlike asthma, airway obstruction is minimally reversible with bronchodilators, such as salbutamol. Patients are susceptible to exacerbations, during which their lung function worsens. Exacerbations triggered by infection are called infective exacerbations of COPD.
• A typical presentation of COPD is a long-term smoker with persistent symptoms of shortness of breath, cough, sputum production, wheeze, and recurrent respiratory infections, particularly in winter.
• COPD does NOT cause clubbing, haemoptysis (coughing up blood), or chest pain. These symptoms should be investigated for a different cause, such as lung cancer, pulmonary fibrosis, or heart failure.
• The MRC (Medical Research Council) Dyspnoea Scale is a 5-point scale for assessing breathlessness:
• MRC Dyspnoea Scale


  1. Grade 1: Breathless on strenuous exercise

  2. Grade 2: Breathless on walking uphill

  3. Grade 3: Breathlessness that slows walking on the flat

  4. Grade 4: Breathlessness stops them from walking more than 100 meters on the flat

  5. Grade 5: Unable to leave the house due to breathlessness
• Diagnosis of COPD is based on the clinical presentation and spirometry results. Spirometry will show an obstructive picture with a FEV1:FVC ratio of less than 70%. There is little or no response to reversibility testing with beta-2 agonists (e.g., salbutamol).
• Diagnosis


  Based on the clinical presentation and spirometry results
• Spirometry


  • Shows an obstructive picture with a FEV1:FVC ratio of less than 70%
• Little or no response to reversibility testing with beta-2 agonists (e.g., salbutamol) is more suggestive of asthma
• Severity


  Graded using the forced expiratory volume in 1 second (FEV1)
• Severity stages


  • Stage 1 (mild): FEV1 more than 80% of predicted
  • Stage 2 (moderate): FEV1 50-79% of predicted
  • Stage 3 (severe): FEV1 30-49% of predicted
  • Stage 4 (very severe): FEV1 less than 30% of predicted
• Other investigations


  • Body mass index, Chest x-ray, Full blood count, Sputum culture, ECG, Echocardiogram, CT thorax, Serum alpha-1 antitrypsin, Transfer factor for carbon monoxide
• Long-Term Management


  Includes smoking cessation, vaccines, pulmonary rehabilitation, initial medical treatment
• Initial medical treatment


  • Short-acting beta-2 agonists (e.g., salbutamol), Short-acting muscarinic antagonists (e.g., ipratropium bromide)
• Second step treatment


  Determined by asthmatic or steroid-responsive features
• Combination inhalers for different features

  • LABA and LAMA combination inhalers, LABA and ICS combination inhalers, LABA, LAMA, and ICS combination inhalers
• Additional options for severe cases

  • Nebulisers, Oral theophylline, Oral mucolytic therapy, Prophylactic antibiotics, Oral corticosteroids, Oral phosphodiesterase-4 inhibitors, Long-term oxygen therapy at home, Lung volume reduction surgery, Palliative care
• Patients taking azithromycin need ECG and liver function monitoring before and during treatment
• Long-term oxygen therapy (LTOT) is used for severe COPD with chronic hypoxia, polycythaemia, cyanosis, or cor pulmonale. Smoking is a contraindication due to the fire risk
• Cor pulmonale


  Refers to right-sided heart failure caused by respiratory issues
• Long-term oxygen therapy (LTOT)


  Used for severe COPD with chronic hypoxia (sats < 92%), polycythaemia, cyanosis, or cor pulmonale
• Cor Pulmonale


  Refers to right-sided heart failure caused by respiratory disease
• Pulmonary hypertension


  Increased pressure and resistance in the pulmonary arteries limiting the right ventricle pumping blood into the pulmonary arteries
• Causes of cor pulmonale

  • COPD (the most common cause)
  • Pulmonary embolism
  • Interstitial lung disease
  • Cystic fibrosis
  • Primary pulmonary hypertension
• Patients with early cor pulmonale are often asymptomatic
• Symptoms of cor pulmonale

  • Shortness of breath
  • Peripheral oedema
  • Breathlessness of exertion
  • Syncope (dizziness and fainting)
  • Chest pain
• Signs of cor pulmonale on examination

  • Hypoxia
  • Cyanosis
  • Raised JVP (jugular veins)
  • Peripheral oedema
  • Parasternal heave
  • Loud second heart sound
  • Murmurs (e.g., pan-systolic in tricuspid regurgitation)
  • Hepatomegaly due to back pressure in the hepatic vein (pulsatile in tricuspid regurgitation)
• Management of cor pulmonale

  Involves treating the symptoms (e.g., diuretics for oedema) and the underlying cause. Long-term oxygen therapy is often used. The prognosis is poor unless there is a reversible underlying cause
• An acute COPD exacerbation presents rapidly worsening symptoms such as cough, shortness of breath, sputum production, and wheezing. Viral or bacterial infection often triggers it
• Arterial Blood Gas


  An acute exacerbation of COPD typically causes a respiratory acidosis involving: Low pH indicates acidosis, Low pO2 indicates hypoxia and respiratory failure, Raised pCO2 indicates CO2 retention (hypercapnia), Raised bicarbonate indicates chronic retention of CO2
• Low pH with a raised pCO2 suggests they are acutely retaining CO2, making their blood acidotic, indicating respiratory acidosis. Raised bicarbonate indicates they chronically retain CO2. Their kidneys have responded by producing more bicarbonate to balance the acidic CO2 and maintain a normal pH. During an acute exacerbation, the kidneys cannot keep up with the rising level of CO2, so the blood becomes acidotic despite a raised bicarbonate
• Other investigations used during an acute exacerbation

  • Chest x-ray to look for pneumonia or other pathology, ECG to look for arrhythmias or evidence of heart strain, Full blood count to look for infection (raised white blood cells), U&E to check electrolytes, which can be affected by infections and medications, Sputum culture, Blood cultures in patients with signs of sepsis (e.g., fever)
• Many patients with COPD retain CO2 when treated with oxygen, referred to as oxygen-induced hypercapnia. The mechanism for this is complex and likely involves ventilation-perfusion mismatch and haemoglobin binding less well to CO2 when also bound to oxygen. Target oxygen saturations of 88-92% are used for patients with COPD at risk of retaining CO2. These may be adjusted to 94-98% when confident they do not retain CO2
• Venturi masks are designed to deliver a specific percentage concentration of oxygen. They allow some of the oxygen to leak out the side of the mask and normal air to be inhaled along with oxygen. Environmental air contains 21% oxygen. Venturi masks deliver 24% (blue), 28% (white), 31% (orange), 35% (yellow), 40% (red) or 60% (green) oxygen
• Management of an Acute Exacerbation

  First-line medical treatment of an acute exacerbation of COPD involves: Regular inhalers
• Oxygen delivery percentages in Venturi masks

  • 24% (blue)
  • 28% (white)
  • 31% (orange)
  • 35% (yellow)
  • 40% (red)
  • 60% (green)