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Smoke Inhalation Injury
Aka: Smoke Inhalation Injury, Smoke Inhalation, Inhalation Injury
- Epidemiology
- Leading cause of death from Burn Injury (responsible for 50-80% of burn-related deaths)
- Pathophysiology
- Upper airway is typically affected (except in steam inhalation which can affect sub-glottic airway)
- Inhalation injuries are mediated by chemical lung injury (not typically heat)
- Results in large volume fluid influx into the lungs
- Signs: Findings suggestive of Smoke Inhalation
- Altered Mental Status
- Burn Injury alone should not alter mentation
- Full thickness facial burns
- Singed facial hair
- Oral and nasal mucosal Burn Injury
- Burn Injury occuring in a confined space
- Sputum with soot (carbonaceous Sputum)
- Hoarseness or Stridor
- Bullae in oropharynx or Larynx
- Cough
- Signs: Respiratory distress (late findings)
- Dyspnea
- Tachypnea
- Wheezing
- Rhonchi
- Nasal flaring or chest retractions
- Labs
- Arterial Blood Gas
- Serum Lactic Acid
- Increased with cyanide Poisoning
- No specific Cyanide lab testing in most clinical settings
- Carboxyhemoglobin level
- Increased with Carbon Monoxide Poisoning
- Continuous finger probe Carboxyhemoglobin monitoring is commercially available
- Complete Blood Count
- Consider serum Troponin
- Indicated for Chest Pain, EKG changes or increased cardiovascular risk
- Imaging
- Chest XRay
- Typically normal early in course of Inhalation Injury
- Diagnostics
- Electrocardiogram
- Observe for Myocardial Ischemia
- Pulmonary Function Tests
- Nasolaryngoscopy
- Bronchoscopy
- Evaluate the extent of upper airway and Bronchial injury
- Complications
- Carbon Monoxide Poisoning
- Cyanide Poisoning
- Results from inhalation of burning materials (e.g. wool, silk, polyurethane, plastics and vinyl)
- Consider in residential and industrial fires, especially if concurrent Carbon Monoxide Poisoning
- Hypotension may be the only initial finding
- Late findings include decreased mental status, Bradycardia, respiratory depression and cardiovascular collapse
- Methemoglobinemia
- Respiratory injury
- Particulate matter and sulfur and nitrogen compounds result in direct lung injury and VQ Mismatch
- Causes Hypoxia, airway edema, airway obstruction and ARDS
- Evaluation
- Altered Mental Status
- Burn Injury alone is typically associated with alert, Agitated Patient in pain
- Decreased level of conciousness suggests other cause
- Carbon Monoxide Poisoning
- May be associated with Headache, Nausea, Vomiting, Dizziness, myalgias
- Cyanide Poisoning
- Head Trauma
- Management
- See Burn Injury
- Monitoring
- Intravenous Access
- Oxygen Saturation monitoring
- Telemetry monitoring
- Interventions: Airway
- Supplemental Oxygen 100% Non-Rebreathing Mask
- Continue until Carboxyhemoglobin <5% (at least <10% in smokers)
- Carbon Monoxide decreases 50% in 60 minutes on Non-Rebreather Mask
- Carbon Monoxide decreases 50% in 30 minutes on 100% oxygen while intubated
- Consider hyperbaric oxygen (see indications below)
- Consider Advanced Airway and Mechanical Ventilations
- Monitor upper airway closely and prophylactically intubate early if airway compromise is suspected
- Mechanical Ventilation settings
- Keep Tidal Volumes at 3-5 ml/kg
- Keep plateau pressures <30 cm H2O
- Administer PEEP
- Rapid Sequence Intubation precautions
- Succinylcholine is safe in acute Burn Injury (Hyperkalemia risk starts at 5 days post-injury)
- Endotracheal Tube precautions
- Place at least a 7.5 Endotracheal Tube (otherwise more difficult suctioning, bronchoscopy)
- Endotracheal Intubation indications
- Includes all standard intubation indications
- See Advanced Airway
- Respiratory Failure
- Altered Mental Status
- Unprotected airway or inability to handle own secretions
- Expectation of further tracheal edema within next 24 hours
- Hoarseness or increasing Stridor (upper airway obstruction)
- Severe Third Degree Burns to face or oropharynx
- Prolonged transport and tenuous airway status
- Respiratory Muscle Fatigue
- Hypoventilation (PCO2>50 mmHg and pH <7.20)
- Hypoxemia despite maximal Supplemental Oxygen
- Carbon Monoxide >20% may require intubation due to Hypoxemia
- Other interventions
- Intravenous crystalloid
- See Burn Management (includes Parkland Formula)
- Maintain urinary output of 0.5 to 1 mL/kg/hour
- Opioid Analgesics
- Airway adjuncts to consider
- Bronchodilators (e.g. Nebulized Albuterol) for Wheezing, or Asthma Exacerbation
- Nebulized Epinephrine
- Consider for temporary stabilization of upper airway symptoms until definitive management
- Inhaled Mucolytics (may help clear fibrin, mucus and debris from airway)
- Inhaled N-Acetylcysteine
- Inhaled Heparin
- Systemic Corticosteroids may be indicated in certain inhalations
- Examples: Nitrogen oxide, Zinc Oxide, sulfur trioxide, titanium tetrachloride
- Discuss with poison control, pulmonology or burn center
- Cyanokit (IV Hydroxycobalamin)
- Empiric therapy for suspected cyanide Poisoning
- Indications (Paris Fire Brigade Protocol)
- Known Smoke Inhalation in an enclosed space AND
- One of the following criteria
- Altered Mental Status
- Soot in nares or mouth
- Full cardiopulmonary arrest (without full body burns incompatible with life)
- Dosing
- Hydroxycobalamin (Vitamin B12a) 70 mg/kg up to 5 grams IV over 15 minutes
- May give a second dose up to 5 grams
- Efficacy
- Resulted in 50% ROSC rate in full arrest Smoke Inhalation patients
- Much safer empiric therapy than the Lily Kit (Methemoglobinemia, Hypotension)
- Hydroxycobalamin neutralizes Cyanide without affecting cellular oxygen use
- Adverse Effects
- Skin Flushing
- Red pigmented urine
- References
- Fortin (2006) Clin Toxicol 44 (suppl 1):37-44 +PMID:16990192 [PubMed]
- Borron (2007) Ann Emerg Med 49(6): 794-801 +PMID:17481777 [PubMed]
- Disposition
- Monitor in Emergency Department for at least 4-6 hours
- Observe with serial exams, Vital Signs and diagnostics
- Discharge with close interval follow-up if normal observation without significant airway symptoms
- Hospitalization indications
- Enclosed space inhalation exposure for >10 minutes
- Sputum with soot
- pAO2 <60 mmHg
- Metabolic Acidosis
- Increased Anion Gap and Lactic Acidosis with cyanide Poisoning
- Carboxyhemoglobin >15%
- A-a Gradient >100 mmHg on 100% Supplemental Oxygen
- Significant symptoms or signs (Central facial burns, painful swallowing or bronchospasm)
- Hyperbaric oxygen therapy indications
- Base Excess < -2 mmol/L
- Carboxyhemoglobin >25% (or >20% in pregnancy, in which fetal Hemoglobin is more CO avid)
- Cerebellar symptoms (e.g. Ataxia) or Altered Mental Status
- Pulmonary Edema
- Cardiac Arrhythmia or Acute Coronary Syndrome
- Very young or very old
- References
- Lafferty in Alcock (2013) Smoke Inhalation Injury, Medscape EMedicine (accessed 12/11/2013)
- Latenser in Bope (2011) Burn Treatment Guidelines, Conn's Current Therapy, Elsevier, p. 1151
- Schwartz in Cydulka (2011) Tintinalli's Emergency Medicine 7ed, McGraw Hill, New York (accessed 12/11/2013)
- http://www.accessmedicine.com/content.aspx?aID=6385384
- Weir (2020) Crit Dec Emerg Med 34(12): 3-11