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Emergency and Acute Medicine – Smoke Inhalation
Smoke inhalation should be suspected in any patient exposed to fire in an enclosed space or with a history of loss of consciousness. It can cause injury through three main mechanisms: direct thermal injury to the upper airway, chemical irritation of the lower airway, and systemic toxicity from inhaled substances such as carbon monoxide and hydrogen cyanide. Notably, steam inhalation is especially dangerous due to its extremely high heat-carrying capacity, which can rapidly cause severe airway edema and obstruction.
Thermal injury is typically limited to supraglottic structures because the upper airway dissipates heat effectively. However, inhaled irritants can damage lower airway structures, leading to bronchospasm, inflammation, and impaired gas exchange. Systemic toxicity occurs when gases like carbon monoxide impair oxygen delivery or cyanide disrupts cellular respiration.
Patients often present with a history of smoke exposure, especially in confined spaces. Early symptoms may be mild or even absent, with deterioration occurring over the next 24 hours. Upper airway findings include hoarseness, stridor, cough, and nasopharyngeal irritation. Lower airway involvement may present with chest discomfort, hemoptysis, bronchospasm, and excessive secretions. Classic warning signs of significant inhalation injury include facial burns, singed nasal hairs, and carbonaceous sputum.
Evaluation includes pulse oximetry, though it may be falsely normal in carbon monoxide poisoning. Arterial blood gas analysis may reveal hypoxia or metabolic acidosis, particularly in cases of carbon monoxide or cyanide toxicity. Chest radiographs are often initially normal but may show pulmonary changes later. Laboratory testing should include carboxyhemoglobin levels for suspected carbon monoxide exposure and lactate as a marker for cyanide toxicity. Cyanide levels can be measured but treatment should not be delayed while awaiting results.
Management begins with immediate administration of 100% oxygen via face mask. Early intubation is critical in patients with signs of airway compromise such as stridor, drooling, respiratory distress, or altered mental status. Bronchospasm can be treated with nebulized bronchodilators such as albuterol, and corticosteroids may be considered in patients with underlying asthma or COPD.
For carbon monoxide toxicity, treatment includes high-flow oxygen and, in selected cases, hyperbaric oxygen therapy. Cyanide toxicity should be treated promptly with hydroxocobalamin (preferred), or with sodium thiosulfate if necessary. Care must be taken with nitrite-based antidotes in patients with concurrent carbon monoxide exposure.
Patients requiring intubation, those with significant burns, persistent respiratory symptoms, or evidence of toxic exposure should be admitted. Patients with minimal exposure who remain asymptomatic after a period of observation (typically 4–6 hours) may be discharged with clear return precautions.
Key points include maintaining a high index of suspicion even with initially normal findings, recognizing that pulse oximetry can be misleading, initiating early oxygen therapy, and not delaying treatment for suspected cyanide toxicity.
Smoke inhalation should be suspected in any patient exposed to fire in an enclosed space or with a history of loss of consciousness. It can cause injury through three main mechanisms: direct thermal injury to the upper airway, chemical irritation of the lower airway, and systemic toxicity from inhaled substances such as carbon monoxide and hydrogen cyanide. Notably, steam inhalation is especially dangerous due to its extremely high heat-carrying capacity, which can rapidly cause severe airway edema and obstruction.
Thermal injury is typically limited to supraglottic structures because the upper airway dissipates heat effectively. However, inhaled irritants can damage lower airway structures, leading to bronchospasm, inflammation, and impaired gas exchange. Systemic toxicity occurs when gases like carbon monoxide impair oxygen delivery or cyanide disrupts cellular respiration.
Patients often present with a history of smoke exposure, especially in confined spaces. Early symptoms may be mild or even absent, with deterioration occurring over the next 24 hours. Upper airway findings include hoarseness, stridor, cough, and nasopharyngeal irritation. Lower airway involvement may present with chest discomfort, hemoptysis, bronchospasm, and excessive secretions. Classic warning signs of significant inhalation injury include facial burns, singed nasal hairs, and carbonaceous sputum.
Evaluation includes pulse oximetry, though it may be falsely normal in carbon monoxide poisoning. Arterial blood gas analysis may reveal hypoxia or metabolic acidosis, particularly in cases of carbon monoxide or cyanide toxicity. Chest radiographs are often initially normal but may show pulmonary changes later. Laboratory testing should include carboxyhemoglobin levels for suspected carbon monoxide exposure and lactate as a marker for cyanide toxicity. Cyanide levels can be measured but treatment should not be delayed while awaiting results.
Management begins with immediate administration of 100% oxygen via face mask. Early intubation is critical in patients with signs of airway compromise such as stridor, drooling, respiratory distress, or altered mental status. Bronchospasm can be treated with nebulized bronchodilators such as albuterol, and corticosteroids may be considered in patients with underlying asthma or COPD.
For carbon monoxide toxicity, treatment includes high-flow oxygen and, in selected cases, hyperbaric oxygen therapy. Cyanide toxicity should be treated promptly with hydroxocobalamin (preferred), or with sodium thiosulfate if necessary. Care must be taken with nitrite-based antidotes in patients with concurrent carbon monoxide exposure.
Patients requiring intubation, those with significant burns, persistent respiratory symptoms, or evidence of toxic exposure should be admitted. Patients with minimal exposure who remain asymptomatic after a period of observation (typically 4–6 hours) may be discharged with clear return precautions.
Key points include maintaining a high index of suspicion even with initially normal findings, recognizing that pulse oximetry can be misleading, initiating early oxygen therapy, and not delaying treatment for suspected cyanide toxicity.
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