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 calls for high-dose glucocorticoid therapy either intravenously or as tablets (40–80 mg 4 times per 24 hours).
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

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

Acute respiratory tract reactions induced by external factors is a sample topic from the Evidence-Based Medicine Guidelines.

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