Chronic obstructive pulmonary disease

From IDWiki

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

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
  • 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