Asthma COPD overlap syndrome

• What is Asthma COPD Overlap Syndrome (ACOS)?


  Clinical condition

  Characterised by persistent airflow limitation with several features (usually associated with both asthma & COPD)
• What are the investigations for ACOS?

  Spirometry (obstructive pattern)

  Bronchial challenge test (used when spirometry results are inconclusive)

  CXR

  CT

  FBC

  IgE

  ABG

  Allergy testing

  Sputum analysis
• Why is a CXR done in ACOS?


  Rule out differentials

  Identify complications (pneumonia, pneumothorax)

  May show hyperinflated lungs, flattened diaphragm

  May show signs of pulmonary HTN (severe cases)
• What is an obstructive pattern in spirometry?


  Reduced FEV1

  Reduced FEV1/FVC

  Poor reversibility to bronchodilators
• Why is CT done in ACOS?


  Can show features of emphysema & airway disease
• Why is FBC done in ACOS?


  May show raised eosinophil count (asthmatic component)
• Why are IgE levels done in ACOS?


  Elevated levels support asthma

  Not to be used in isolation for diagnosis of ACOS
• What might be seen on an ABG for ACOS?


  Possible hypoxaemia & hypercapnia (severe cases)
• Why might allergy testing be done in ACOS?


  Skin prick or specific IgE bloods

  To identify potential allergens (if allergic asthma is suspected as part of ACOS picture)
• What might sputum analysis be done in ACOS?


  Not routinely done

  Eosinophilic inflammation → more asthma

  Neutrophilic inflammation → more COPD
• What are the DDx of ACOS?


  COPD

  Asthma

  Bronchiectasis
• What are the RFs for ACOS?


  Genetic predisposition

  Exposure of airborne pollutants

  Allergen exposure

  Smoking

  Poorly controlled asthma

  Recurrent resp infections (esp in childhood)

  Older age
• How is the exposure to airborne pollutants a RF for ACOS?


  Long term exposure can lead to chronic inflammation & oxidative stress in airways
• How is allergen exposure a RF for ACOS?


  Allergen sensitisation can lead to eosinophilic inflammation
• How is smoking a RF for ACOS?


  Induces airway inflammation & accelerates lung function
• How is poorly controlled asthma a RF for ACOS?


  Can progress into fixed airflow obstruction resembling COPD over time
• How are recurrent resp infections a RF for ACOS?


  Infections → airway damage & remodelling → persistent airflow obstruction
• How is older age a RF for ACOS?


  Prevalence of ACOS increased with age

  Suggests age-related changes in lung structure contribute to aetiology
• What are the signs & symptoms of ACOS?


  Dyspnoea

  Cough (often productive with clear/white sputum)

  Wheeze

  Chest tightness

  Hyperinflation

  Use of accessory muscles

  Signs of cor pulmonale (advances stages - peripheral oedema & raised JVP)
• What is the treatment & management of ACOS?


  Assess severity & RFs (MRC dyspnoea scale or COPD Assessment Test)

  Medication

  • ICS combined w/LABA (1st line)
  • Can add on LAMA (pts who are symptomatic or have frequent exacerbations)
  • Consider short-acting bronchodilators for rescue therapy

  Patient education & self-management

  Lifestyle modification (smoking cessation, maintain optimal body weight)

  Manage comorbidities (CVD, osteoporosis, anxiety & depression)

  Regular follow ups for...

  • symptoms
  • exacerbations
  • inhaler technique
  • adherence to treatment
• What is the pathophy of ACOS?


  Exposure to smoking or allergens → airway inflammation & oxidative stress → cytokine & ROS release (IL-33, TSLP & IL-25) → activation of innate immune cells → eosinophil recruitment & activation → mucous hypersecretion, subepithelial fibrosis, smooth muscle hypertrophy & airway hyperresponsiveness

  Prolonged exposure → airway remodelling

  • goblet cell metaplasia → excessive mucous production
  • smooth muscle hypertrophy → bronchoconstriction
  • subepithelial fibrosis → thickening of airway walls

  → irreversible airflow limitation
• What does airway inflammation look like in ACOS?


  Both neutrophilic & eosinophilic inflammation