Cough

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

• 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