T2 L16: Why we cough / breathlessness

• What is cough?

  part of immune system

  innate response to external irritating stimulus to airway

  protective reflex preventing aspiration and enhancing airways clearance
• What is the mechanism of the cough reflex?

  cough centre in medulla → efferent nerves → cough → cough receptors → afferent nerves → vagus nerve → back to cough centre
• What are the nervous properties of the cough reflex?

  c-fibres (chemical response)

  rapidly and slow acting
• What are the different characterisations of cough?

  Acute (<3 weeks)

  Sub-acute (3-8 weeks)

  Chronic (>8 weeks)
• What are the possible causes of an acute cough (<3 weeks)?

  Infectious (most common): viral / pneumonia

  Non-infectious:

  • exacerbation (COPD / asthma)
  • pulmonary embolism
  • pulmonary oedema
• What are the possible causes of a sub-acute cough (3-8 weeks)?

  Post infectious: on going inflammation of epithelial cells, increased mucus production by goblet cells, hypersensitivity of afferent nerves

  Smoking-related
• What are the possible causes of a chronic cough (>8 weeks)?

  Asthmatic cough / eosinophilic bronchitis

  Reflux cough

  Post nasal drip / upper airways cough synfrome

  Iatrogenic cough - ACE inhibitors (Enalapril, Ramipril)

  Chronic refractory cough
• What is the prevalence of chronic cough?

  5-10% of population

  2/3 female

  when severe results in a major impact on QoL: cough incontinence, cough syncope, dysphoria, social isolation, depression
• What are the cough red flags?

  Haemoptysis

  Change voice

  Peripheral oedema

  Smokers with a new cough / change in cough

  Trouble swallowing

  Vomiting
• What is the epidemiology breathlessness?

  aged >40 years around 27%

  more common in older people, female, overweight, smokers, lower socioeconomic status

  in emergency department around 35% people report breathlessness
• What is the neuroscience of breathlessness?

  perception is important

  prediction takes into account past experiences, mood, environmental cues
• What are the different classifications of breathlessness?

  Acute (minutes)

  Sub-acute (hours/days)

  Chronic (weeks/months)
• What are some respiratory causes of breathlessness?

  asthma, COPD, pneumonia, pulmonary embolism, lung cancer, pleural effusion
• What are the cardiac causes of breathlessness?

  myocardial infarction, cardiac arrhythmia, pulmonary oedema, chronic heart failure
• What are the other causes of breathlessness?

  anaemia, psychological
• What are the breathlessness red flag symptoms?

  chest pain (PE, MI)

  leg swelling (cardiac failure, DVT)

  haemoptysis (infection, PE, cancer)

  fever/night sweats (infection, TB)

  Noisy breathing (eg stridor)