Chronic obstructive pulmonary disease

Background

• Slowly progressive disease involving airways and lung parenchyma characterized by persistent airflow limitation

Etiology

• Tobacco smoke is by far the most common cause
  • Usually >10 pack-year history
• Biofuel smoke (wood, animal dung, coal, crop residues), organic or inorganic dust, chronic untreated asthma, air pollution

Risk Factors

• Smoking
• Age
• Biofuel use

GOLD Classification

• Class I (mild): FEV1 ≥80%
• Class II (moderate): FEV1 50-79%
• Class III (severe): FEV1 30-49%
• Class IV (very severe): FEV1 ≤29%

Clinical Manifestations

• Dyspnea, chronic cough or sputum production
• Match test (cannot blow out a lit match)

Differential Diagnosis

• Dyspnea
• Pulmonary disease
  • Airways: asthma, bronchiectasis
  • Parenchyma: ILDs
  • Vessels: PH, PE
• Chronic cough

Diagnosis

• Pulmonary function tests (PFTs)
  • Post-bronchodilator FEV1/FVC ratio <0.7 for diagnosis
  • Possibly elevated TLC (gas trapping) and low DLCO (suggests emphysema)

Management

Acute

• See Acute exacerbation of COPD

Chronic

• Preventative/non-pharmacologic
  • Smoking cessation (improves survival), education
  • Flu shots, pneumococcal vaccination
  • Pulmonary rehabilitation (improves survival if within 4 weeks of exacerbation)
• Step-wise puffers: note that no puffers improve survival
  • Short-acting anticholinergic bronchodilators prn: ipratropium/salbutamol
  • Long-acting anticholinergic bronchodilators: tiotropium
  • Long-acting beta-agonist: salmeterol or formoterol
  • Inhaled corticosteroid (ICS): decreases frequency of exacerbations, but increases risk of pneumonia
• Home oxygen
  • Improves survival if:
    • Resting PaO2 < 55mmHg
    • Resting PaO2 < 60mmHg plus cor pulmonale
  • Target SpO2 >90%
  • May not improve dyspnea
• If frequent exacerbations, consider roflumilast or azithromycin or NAC
• If daytime pCO2 >52 mmHg, consider home non-invasive ventilation

Surgical Interventions

Lung volume reduction surgery

• Indicated if:
  • Severe COPD
  • Symptomatic despite maximal pharmacologic therapy
  • Completed pulmonary rehabilitation
  • Evidence of bilateral predominant upper-lobe emphysema on CT
  • Postbronchodilator total lung capacity greater than 100% and residual lung volume greater than 150% of predicted
  • Maximum FEV1 greater than 20% and less than or equal to 45% of predicted and DLCO greater than or equal to 20% of predicted
  • Ambient air arterial PCO2 less than or equal to 60 mm Hg (8.0 kPa) and arterial PO2 greater than or equal to 45 mm Hg (6.0 kPa)
• Can decrease mortality in patients with heterogeneous, primarily upper-lobe emphysema

Lung transplantation

• Indicated if:
  • Pulmonary hypertension, cor pulmonale, or both despite oxygen therapy
  • History of exacerbation associated with acute hypercapnia
  • FEV1 less than 20% of predicted with DLCO less than 20% of predicted or homogeneous distribution of emphysema
• Contraindications includes: active smoking or substance use, cancer within 2 years, organ dysfunction, incurable chronic infection, anatomical abnormalities, lack of social support, or untreated psychiatric disorder
• Improves quality of life

Symptomatic Management of Advanced COPD

• Can use oral opioids for dyspnea
• Walking aids and pursed-lip breathing
• Home oxygen if hypoxemic at rest, but may not affect quality of life
• Also: neuromuscular electrical muscule stimulation and chest wall vibration
• No role for anxiolytics or antidepressants

Further Reading

• CTS guidelines
• TORCH trial: Jenkins CR, et al. Efficacy of salmeterol/fluticasone propionate by GOLD stage of chronic obstructive pulmonary disease: analysis from the randomised, placebo-controlled TORCH study. Respir Res. 2009;10(1):59.
  • LABA+ICS decreased exacerbations and hospitalizations compared to either alone, but ICS increased pneumonia