Chapter: Modern Medical Toxicology: Asphyxiant Poisons: Toxic Gases

Smoke - Systemic Asphyxiant Poison

Smoke is defined as a solid aerosol resulting from the incom-plete combustion (pyrolysis) of any organic matter, and should be differentiated from “fumes” which refer to a suspension of fine solid particles in a gas resulting from condensation (e.g. metal oxides generated during smelting, welding, etc.).

Smoke

· Smoke is defined as a solid aerosol resulting from the incom-plete combustion (pyrolysis) of any organic matter, and should be differentiated from “fumes” which refer to a suspension of fine solid particles in a gas resulting from condensation (e.g. metal oxides generated during smelting, welding, etc.). The exact composition of smoke depends on the material burnt (Table 26.5).

Diagnosis

· Arterial blood gas analysis.

· Carboxyhaemoglobin and methaemoglobin concentrations.

· Chest X-ray (may be normal in the early stages). Xenon ventilation studies can detect small airway and alveolar injury before radiographic changes become apparent.

· Spirometry: with special reference to FEV₁.

· Other tests of value include EKG, SMA-6, slit lamp exam of the eyes, indirect laryngoscopy and pulmonary function tests (Xenon 133 lung scan, bronchoscopy, and 99mTc DTPA clearance).

Treatment

· An evaluation of the exposure setting may help the physician determine the amount and type of toxic substances to which the victim has been exposed. Factors of potential importance include open vs closed space, estimated length of exposure, presence or absence of steam, explosion, nature of burning material and packaging, status of other victims and the amount, colour, and odour of smoke.

· Remove victim from environment, decontaminate, secure airway, ventilate, establish intravenous access, monitor cardiac rhythm, treat pulmonary oedema and commence burn care if required.

· Oxygen.

· Aspirate tracheal secretions.

· Bronchodilators (parenteral or nebulised inhalation). Use aminophylline for bronchospasm.

· Mechanical ventilation, PEEP for pulmonary oedema.

· Management of CO or cyanide toxicity if present, on conventional lines.

· Methaemoglobinaemia (more than 20 to 30%) can be treated with methylene blue. The usual adult dose is 1 to 2 mg/kg IV over 5 minutes, followed by a 15 to 30 ml fluid flush to minimise local pain. For children, the usual recom-mended dose is 0.3 to 1 mg/kg.

· Use dexamethasone, mannitol, furosemide for cerebral oedema.

· Consider the use of hyperbaric oxygen, especially in those cases where carbon monoxide and hydrogen cyanide are thought to be present.

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Modern Medical Toxicology: Asphyxiant Poisons: Toxic Gases : Smoke - Systemic Asphyxiant Poison |