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    Abbreviated Injury Score (AIS) for Inhalation Injury

    Classifies inhalation injury severity based on bronchoscopic findings.


    Use in adult patients with suspected inhalation injury undergoing flexible bronchoscopy.

    When to Use
    Why Use

    Adult patients with suspected inhalation injury undergoing flexible bronchoscopy.

    • May predict development of ARDS, length of time on mechanical ventilation, and prolonged ICU stay.
    • Some studies have found a non-statistically significant trend towards worse outcomes with higher AIS.
    • AIS severity has not been consistently associated with mortality (Sheridan 2016).
    • Cannot reliably predict need for high fluid resuscitation requirements.
    • A typical flexible bronchoscope is on average 5 mm in diameter. Hence, bronchoscopy can only identify proximal airway changes and not the narrower distal and peripheral airway changes. Thus, bronchoscopic findings cannot be fully relied upon to accurately reflect the overall severity of airway inhalation injury.
    • No universal consensus exists on grading for inhalation injury. The AIS has been widely utilized as the predominant bronchoscopic inhalation injury severity score in the literature (but have not been compared head to head with other bronchoscopic criteria).
    • Of note, a multicenter prospective cohort study by the American Burn Association is currently underway to develop and validate a scoring system for inhalation injury based on clinical, radiographic, bronchoscopic, and biochemical parameters.
    No carbonaceous deposits, erythema, edema, bronchorrhea, or obstruction
    Minor or patchy areas of erythema, carbonaceous deposits, bronchorrhea, or bronchial obstruction present
    Moderate erythema, carbonaceous deposits, bronchorrhea, or bronchial obstruction present
    Severe inflammation with friability, copious carbonaceous deposits, bronchorrhea, or obstruction present
    Mucosal sloughing, necrosis, or endoluminal obstruction present


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    Creator Insights


    High AIS severity alone should not dictate management decisions, which should as always be made in conjunction with history, physical exam, and laboratory findings.


    • Supportive treatment is the primary means of inhalation injury management, as there is very little in the way of pharmacologic treatment once the inhalation injury has occurred.
    • Bronchoscopy can play a therapeutic role in airway clearance as necrotic tissue and eschar can form pseudomembranes, sloughing of mucosa, and bronchial obstruction.
    • Other measures include intensive bronchial hygiene, including bronchodilators (e.g. inhaled β2 agonists), frequent chest physiotherapy, and early patient ambulation).
    • Upper airway edema can progress, particularly over the first 24 hours after injury, necessitating intubation. If mechanical ventilation is required, a high frequency percussive mode of ventilation can be considered, as some studies have shown benefit to this patient population. A lung-protective, low tidal volume ventilation strategy (6-8 cc/kg of predicted body weight) is preferred in adults.
    • Other supportive measures have been used with varied success, including prone positioning, extracorporeal membrane oxygenation (ECMO), inhaled anticoagulants (e.g. heparin, antithrombin), and inhaled N-acetylcysteine (NAC).
    • Additionally, referral to a designated burn center should be considered if any inhalation injury is present, according to American Burn Association guidelines.

    Critical Actions

    Macroscopic manifestations of airway abnormalities may be delayed and hence, falsely reassure the clinician that inhalation injury has not occurred (Hunt 1975).

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