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Eija-RiittaSalomaa

Acute Respiratory Tract Reactions Induced by External Factors

Essentials

  • Sudden exposure to irritating chemicals may cause transitory symptoms of respiratory tract irritation, but in the most severe cases it may lead to pulmonary oedema and even death.
  • Immediately starting treatment with inhaled and systemic glucocorticoid aims at preventing the development of asthma and pulmonary oedema.
  • If strong exposure is suspected, the patient should be followed up in a hospital for a few days.
  • Further investigations at the pulmonary outpatient clinic are indicated.
  • It is important to refer exposed employees and other persons without delay to health care services in order to start inhaled glucocorticoid treatment.

Exposure

  • Fires
    • Mixtures of various gases and particulate substances
    • E.g., acrolein is released from burning oil products and plastics.
  • Industrial exposure
    • Gases released in industrial processes
    • Gas leaks in industrial plants and during transportation

Causes

  • Strong alkali (e.g. ammonia and caustic soda) and acids as well as strongly oxidizing agents (e.g. hydrogen peroxide and ozone) and inorganic chlorine and sulphur compounds are typical causes.
  • Any irritant gas can cause life-threatening alveolar injury if the exposure is very intensive or lasts long.

Manifestations

  • The symptoms caused by the exposure may be manifested in many different forms. Below they are ordered from the mildest to the most severe ones.
    • RUDS (reactive upper airway dysfunction syndrome)
      • Acute rhinitis
      • Acute maxillary sinusitis
      • Laryngitis or bronchitis with associated cough, pharyngeal irritation and a need to clear the throat
    • Obliterating bronchiolitis
      • The symptoms start acutely and then alleviate but worsen again after 1 to 3 weeks.
    • Irritant-induced asthma (formerly RADS, reactive airways dysfunction syndrome)
      • Asthma-like symptoms, particularly cough
      • May subside within some months but may also remain chronic
    • Acute toxic pneumonitis
      • Dyspnoea that may only appear after 4 to 72 hours after the exposure
      • Often leads to a life-threatening condition that is similar to pulmonary oedema.

Investigations

Emergency investigations

  • Chest x-ray
  • Oxygen saturation or arterial blood sample
  • PEF measurement
  • CRP, basic blood count
  • Clinical status of the upper respiratory tract
  • Full blood and urine samples (to be frozen)

Further investigations

  • Performed as soon as the patient's condition allows:
    • spirometry and bronchodilator test
    • histamine or methacholine exposure
    • 24 h follow-up of PEF.

Treatment

Acute treatment

  • First 5 days: the patient is given as soon as possible after the exposure (preferably within 15 minutes) 800-1 200 µg of budesonide or beclomethasone or 500 µg of fluticasone by inhalation using an inhalation chamber, or 2 ml of budesonide 0.5 mg/ml using a nebulizer. The dose is repeated at six-hour intervals.
  • After 5 days: the treatment is withdrawn unless there are pulmonary findings in which case the treatment will be continued until recovery.
  • Intensive exposure: systemic glucocorticoid therapy is considered.
  • Symptomatic treatment as needed
    • Beta-adrenergic agonist for cough and dyspnoea
    • Supplemental oxygen for dyspnoea
    • Racemic adrenaline (S2® Racepinephrine 2.25 %) inhalation for laryngeal obstruction
    • Respiratory support treatment
    • Some substances have a specific antidote. Consult the appropriate local or national authority for more information.

Further treatment

  • Inhaled glucocorticoid at a reduced dose: budesonide or beclomethasone 800 µg twice daily, fluticasone 500 µg twice daily
  • If the patient is asymptomatic during follow-up and the initial respiratory function tests, including histamine or methacholine exposure, were normal, discontinuation of the pharmacological treatment may be considered.

Gradation of care

  • Minor exposure and mild symptoms are treated in outpatient care.
    • High-dose inhaled glucocorticoid for at least 5 days or until the lung function tests have been performed
    • Follow-up visit after 1 to 2 weeks including pulmonary function tests and, if considered necessary, consultation with a pulmonary specialist
  • Intensive exposure or severe symptoms
    • Inhaled glucocorticoid
    • Bronchodilator drugs, supplemental oxygen, systemic glucocorticoid as needed, transfer to specialist care
    • Further investigations and treatment in a pulmonary department