Smoke Inhalation, Emergency Medicine

Basics

Description

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 monoxide
- Hydrogen 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 irritation
- Hoarseness
- Stridor
- Cough
Lower airway:
- Chest discomfort
- Hemoptysis
- Bronchospasm
- Bronchorrhea
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:
- Hypoxia
- Metabolic acidosis in cases of carbon monoxide or hydrogen cyanide
Chest radiography:
- Initial radiograph typically normal
- May 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:
- Respiratory distress
Drooling
Stridor:
- Refractory hypoxia
- CNS depression
- Significant 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 pressure
- Frequent suctioning
- Positive end-expiratory pressure
If indicated, treat for carbon monoxide toxicity:
- 100% oxygen
- Hyperbaric oxygen in appropriate cases when available
If indicated, treat for cyanide toxicity:
- 100% oxygen
- Hydroxocobalamin (preferred)
- If only older nitrite-containing cyanide antidote kit is available
- Sodium nitrite should be used with caution in cases of significant carbon monoxide exposure
- Sodium 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.

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

Home

Erectile Dysfunction

Doctor123.org