Chronic Obstructive Airways Diseasese (COAD)

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Introduction

Chronic obstructive airways diseasese (COAD) is a pulmonary disorder of adults characterized by chronic airflow limitation in the small airways.

It complicates chronic bronchitis and emphysema. Obstruction to air flow is only partially reversible with bronchodilator therapy.

Two extreme types of COAD are recognized although there is a lot of overlap.

Clinical features

This depending on the predominant syndromes, it could be described as follows:

Pink puffers

  • Slowly progressive dyspnoea
  • Cough with scanty sputum
  • Aesthenic features.
  • Barrel-shaped chest
  • Wheeze
    • These patients mainly have emphysema

Blue bloaters

  • Prolonged periods of cough and copious sputum production.
  • Dyspnoea
  • Frequent respiratory infections
  • Central cyanosis
    • These patients mainly have chronic bronchitis

Differential diagnoses

  • Chronic persistent asthma Cystic fibrosis

Complications

  • Respiratory failure
  • Recurrent bronchial infections with
  • Haemophilus influenza and Streptococcus pneumoniae
  • Cor pulmonale
  • Left ventricular failure.
  • Pulmonary thromboembolism

Investigations

  • Chest radiograph: hyperinflation,
    pulmonary hypertension
  • Ventricular function tests: FEV1/FVC ratio
  • Blood gas analysis
  • Blood pH
  • Haematocrit
  • Sputum microscopy and culture (during symptom exacerbation)
  • Electrocardiogram
  • Airways reversibility test

Treatment objectives

  • Maintain optimal level of oxygenation and ventilation
  • Supplemental oxygen, at 24-28% or 1-2 litres/minute
  • Treat infections
  • Reverse airways obstruction
  • Clear airways secretions

Drug treatment

Erythromycin

Adult:

  • 250-500 mg orally every 6 hours, or 500 mg 1 g every 12 hours (up to 4 g daily in severe infections)

Child:

  • 30-50 mg/kg/day PO divided q6-8hr.
    • Double in severe infection. Not to exceed 4 g/day

Amoxicillin Clavulanic acid

Adult:

  • 625mg orally every 12 hours

Child:

  • < 3 months: 30 mg/kg/day PO (125 mg/5 mL) divided q12hr
  • > 3 months: Less severe infections: 20 mg/kg/day PO divided q8hr or 25 mg/kg/day PO

Supportive measures

  • Assisted ventilation
  • Hydration
  • Pulmonary physiotherapy

Prevention

  • Avoidance of cigarette smoking
  • Avoid/remove atmospheric pollutants

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