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Smoke Inhalation, Emergency Medicine

Basics

Description

- Lower airway: - Chest discomfort - Hemoptysis - Bronchospasm - Bronchorrhea

- ABG measurement: - Hypoxia - Metabolic acidosis in cases of carbon monoxide or hydrogen cyanide

- Inhaled or nebulized albuterol as needed for bronchospasm - Corticosteroids as needed for patients with history of asthma or COPD - Intubated patients: - Low endotracheal tube cuff pressure - Frequent suctioning - Positive end-expiratory pressure

  • Suspect smoke inhalation in anyone involved in a fire within a closed space or with a history of loss of consciousness.
  • May cause direct injury to the upper (supraglottic) airway structures
  • May cause chemical/irritant effect to lower airway structures
  • May cause systemic toxicity from inhaled substances

Etiology

  • Direct heat injury from heated gases/smoke:Limited to supraglottic structures because of the heat-dissipating properties of the upper airway
  • Irritant effect from smoke components
  • Systemic toxicity from inhaled cellular toxins:Carbon monoxideHydrogen cyanide

Inhalation of steam can be rapidly fatal:

  • Steam has ¢ ¼4,000 times the heat-carrying capacity of hot air.
  • Can rapidly cause obstructive glottic edema, thermally induced tracheitis, and hemorrhagic edema of the bronchial mucosa

Diagnosis

Signs and Symptoms

History

  • Exposure to a fire or heavy smoke
  • Typically in a confined space
  • Maintain high index of suspicion with history of loss of consciousness

Physical Exam

  • May have a normal physical exam with symptoms developing during the 24-hr interval following exposure
  • Upper airway (supraglottic):Nasopharyngeal irritationHoarsenessStridorCough
  • Lower airway:Chest discomfortHemoptysisBronchospasmBronchorrhea
  • May have symptoms and signs of carbon monoxide and/or cyanide toxicity

The following signs are suggestive of significant inhalation injury:

  • Facial and upper cervical burns
  • Carbonaceous sputum
  • Singed eyebrows and nasal vibrissae

Essential Workup

  • Pulse oximetry:May be falsely elevated in cases of carbon monoxide exposure
  • ABG measurement:HypoxiaMetabolic acidosis in cases of carbon monoxide or hydrogen cyanide
  • Chest radiography:Initial radiograph typically normalMay show signs of pulmonary injury over the next 24 hr

Diagnosis Tests & Interpretation

Lab

  • Electrolytes, BUN, creatinine, glucose
  • CBC
  • Coagulation profile
  • Creatine phosphokinase when indicated in burn patients
  • Carboxyhemoglobin to evaluate for potential carbon monoxide exposure
  • Cyanide level:In suspected cases of cyanide exposure, do not wait for the level before initiating therapy.May send lactate level as a marker of cyanide toxicity
  • Pregnancy test

Diagnostic Procedures/Surgery

  • Peak expiratory flow rate:Low peak flow associated with more severe injury
  • PaO2/FiO2 ratio:A ratio of <300 after initial resuscitation is associated with the development of respiratory failure.

Differential Diagnosis

  • Irritant gas exposure
  • Asphyxiant gas exposure
  • Cardiogenic pulmonary edema
  • COPD exacerbation
  • Asthma exacerbation
  • Pneumonia

Treatment

Pre-Hospital

  • 100% oxygen by face mask
  • Intubation for patients with agonal breathing
  • Rapid transport to ED for those with stridor:May need advanced airway management
  • Albuterol nebulizer therapy for bronchospasm

Initial Stabilization/Therapy

  • 100% oxygen via face mask
  • Intubation:
  • Drooling
  • Stridor:Refractory hypoxiaCNS depressionSignificant facial/upper airway burns
  • Establish IV access.

Ed Treatment/Procedures

  • Inhaled or nebulized albuterol as needed for bronchospasm
  • Corticosteroids as needed for patients with history of asthma or COPD
  • Intubated patients:Low endotracheal tube cuff pressureFrequent suctioningPositive end-expiratory pressure
  • If indicated, treat for carbon monoxide toxicity:100% oxygenHyperbaric oxygen in appropriate cases when available
  • If indicated, treat for cyanide toxicity:100% oxygenHydroxocobalamin (preferred)If only older nitrite-containing cyanide antidote kit is availableSodium nitrite should be used with caution in cases of significant carbon monoxide exposureSodium thiosulfate can be used safely with CO exposures

Medication

  • Albuterol nebulization: 2.5 " 5 mg in 2.5 mL of normal saline q20min:Alternatively, 15 mg nebulizer treatment continuous over 1 hr
  • Methylprednisolone 40 mg IV (peds: 1 " 2 mg/kg)
  • Prednisone: 40 " 60 mg PO (peds: 1 " 2 mg/kg)
  • Sodium thiosulfate 12.5 g (50 mL of 25% solution) slow IV infusion (peds: 412.5 mg/kg or 1.65 mL/kg of 25% solution)
  • Hydroxocobalamin 5 g IV infused over 15 min (peds: 70 mg/kg)

Follow-Up

Disposition

Admission Criteria

  • Intubated
  • Significant associated burns
  • Persistent dyspnea, hoarseness, odynophagia, carbonaceous sputum
  • Persistent cough
  • Asthma/COPD with bronchospasm
  • Significant carbon monoxide or cyanide exposure
  • Comorbid medical illnesses

Discharge Criteria

  • Minimal exposure history
  • Asymptomatic
  • Significant exposure history, asymptomatic after 4 " 6 hr observation

Issues for Referral

  • In cases of significant associated burn injuries, transfer to burn facility as appropriate.
  • In cases of significant carbon monoxide toxicity, transfer to hyperbaric oxygen facility as appropriate.

Followup Recommendations

Burn follow-up for patients with associated burns.

Pearls and Pitfalls

  • In suspected cases of cyanide exposure, do not wait for the level before initiating therapy.
  • Order carboxyhemoglobin to evaluate for potential carbon monoxide exposure.

Additional Reading

  • Peck MD. Structure fires, smoke production, and smoke alarms. J Burn Care Res. 2011;32(5):511 " 518.
  • Rehberg S, Maybauer MO, Enkhbaatar P, et al. Pathophysiology, management and treatment of smoke inhalation injury. Expert Rev Respir Med. 2009;3(3):283 " 297.
  • Toon MH, Maybauer MO, Greenwood JE, et al. Management of acute smoke inhalation injury. Crit Care Resusc. 2010;12(1):53 " 61.

See Also (Topic, Algorithm, Electronic Media Element)

  • Carbon Monoxide
  • Cyanide
  • Hyperbaric Oxygen

Codes

ICD9

  • 506.2 Upper respiratory inflammation due to fumes and vapors
  • 508.2 Respiratory conditions due to smoke inhalation
  • 947.1 Burn of larynx, trachea, and lung
  • 464.10 Acute tracheitis without mention of obstruction
  • 506.0 Bronchitis and pneumonitis due to fumes and vapors
  • 986 Toxic effect of carbon monoxide

ICD10

  • J68.2 Upper resp inflam d/t chemicals, gas, fumes and vapors, NEC
  • J70.5 Respiratory conditions due to smoke inhalation
  • T27.0XXA Burn of larynx and trachea, initial encounter
  • J04.10 Acute tracheitis without obstruction
  • J68.0 Bronchitis and pneumonitis due to chemicals, gases, fumes and vapors
  • J68.9 Unsp resp cond due to chemicals, gases, fumes and vapors
  • T58.91XA Toxic effect of carb monx from unsp source, acc, init

SNOMED

  • 426936004 smoke inhalation injury (disorder)
  • 77304007 Upper respiratory inflammation due to fumes AND/OR vapors (disorder)
  • 284189009 Burn of larynx and/or trachea (disorder)
  • 62994001 Tracheitis (disorder)
  • 420057003 Accidental poisoning by carbon monoxide