Cough

Basics

Description

  • A sudden spasmodic contraction of the thoracic cavity resulting in violent release of air from the lungs and usually accompanied by a distinctive sound:
    • Deep inspiration
    • Glottis closes
    • Expiratory muscles contract
    • Intrapulmonary pressures increase
    • Glottis opens
    • Air expiration at high pressure
    • Secretion and foreign material excretion
    • Vocal cord vibration with tracheobronchial walls, lung parenchyma, and secretions
  • Defense mechanism to clear the airway of foreign material and secretions:
    • Voluntary or involuntary
    • Involuntary coughing regulated by the vagal afferent nerves:
      • Voluntary coughing under cortical control allowing for inhibition or voluntary cough
      • Because of cortical control, placebos can have a profound effect on coughing
    • Reflex involves respiratory tissue receptor activation of afferent neurons to the central cough center followed by efferent output to the respiratory muscles
    • Mechanical receptors in larynx, trachea, and carina sense touch and displacement
    • Chemical receptors in larynx and bronchi are sensitive to gases and fumes
    • Activated by irritants, mucus, edema, pus, and thermal stimuli
  • Complications of severe coughing:
    • Epistaxis
    • Subconjunctival hemorrhage
    • Syncope
    • Pneumothorax
    • Pneumomediastinum
    • Emesis
    • Hernia
    • Rectal prolapse
    • Incontinence
    • Seizures
    • Encephalitis
    • Intracranial hemorrhage
    • Spinal epidural hemorrhage
    • Clubbing
    • Pruriginous rash

Etiology

  • Acute (<3 wk):
    • Pneumonia
    • Acute bronchitis
    • Sinusitis
    • Pertussis
    • Tuberculosis
    • Upper respiratory tract infection
    • Cough variant asthma
    • COPD exacerbation
    • Bronchiectasis
    • Pulmonary embolism
    • Left ventricular failure
    • Airway obstruction (food, pills)
    • GERD
    • Allergies
    • Bronchospasm
  • Subacute (3–8 wk):
    • Postinfectious cough
    • Pertussis
    • Bronchitis
    • Bacterial sinusitis
    • Asthma
    • GERD
    • Pulmonary embolism
  • Chronic (>8 wk):
    • Postnasal drip
    • Asthma
    • GERD
    • Chronic bronchitis
    • Tuberculosis
    • Bronchiectasis
    • Eosinophilic bronchitis
    • ACE inhibitor use
    • Bronchogenic carcinoma
    • Carcinomatosis
    • Sarcoidosis
    • Left ventricular failure
    • Aspiration syndrome
    • Psychogenic/habit

Pediatric Considerations
  • Most frequent causes:
    • Asthma
    • Viral illness
    • Acute bronchitis
    • Pneumonia
    • Sinusitis
    • GERD
  • Less common causes:
    • Tracheobronchomalacia
    • Mediastinal tumor
    • Acyanotic congenital heart disease
    • Ventricular septal defect
    • Patent ductus arteriosus
    • Pulmonary stenosis
    • Tetralogy of Fallot
    • Lodged foreign body
    • Chronic aspiration of milk
    • Environmental exposure
  • Consider:
    • Neonatal history
    • Feeding history
    • Growth and developmental history
    • Allergies
    • Eczema
    • Sleep disorders
  • Indications for CXR:
    • Suspicion of foreign body ingestion
    • Suspect aspiration

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