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    RADS (Radiologist’s Score) for Smoke Inhalation Injury

    Stratifies severity of inhalation injury on chest CT.
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    INSTRUCTIONS

    Requires chest CT to calculate. This tool computes RADS for a single slice; to obtain full score (average RADS per slice), add RADS for all slices and divide by number of slices.

    When to Use
    Pearls/Pitfalls
    Why Use
    • Patients with suspected or diagnosed inhalation injury.
    • Best used in conjunction with flexible bronchoscopy.
    • Score derived from sheep model and validated retrospectively in human cohorts, with limited validation in prospective human clinical trials.
    • Requires assessment of each CT slice, which can be time-consuming.
    • Higher RADS 24 hours after smoke inhalation seems to correlate with greater smoke exposure and severity of lung injury.
    • Using chest CT in the evaluation of inhalation injury has limitations, including questionable optimal timing of CT and interpretation of abnormal CT findings in the setting of a negative bronchoscopy.
    • Currently, no single tool accurately and reliably risk-stratifies and prognosticates patients with smoke inhalation injury.
    • Can be a useful adjunct to determine severity of inhalational injury to the lungs.
    • A multicenter prospective cohort study to develop a scoring system for inhalation injury based on clinical, radiographic, bronchoscopic, and biochemical parameters is underway by the American Burn Association.
    Normal
    0
    Increased interstitial markings
    +1
    Ground glass opacification
    +2
    Consolidation
    +3
    Normal
    0
    Increased interstitial markings
    +1
    Ground glass opacification
    +2
    Consolidation
    +3
    Normal
    0
    Increased interstitial markings
    +1
    Ground glass opacification
    +2
    Consolidation
    +3
    Normal
    0
    Increased interstitial markings
    +1
    Ground glass opacification
    +2
    Consolidation
    +3
    Normal
    0
    Increased interstitial markings
    +1
    Ground glass opacification
    +2
    Consolidation
    +3
    Normal
    0
    Increased interstitial markings
    +1
    Ground glass opacification
    +2
    Consolidation
    +3
    Normal
    0
    Increased interstitial markings
    +1
    Ground glass opacification
    +2
    Consolidation
    +3
    Normal
    0
    Increased interstitial markings
    +1
    Ground glass opacification
    +2
    Consolidation
    +3

    Result:

    Please fill out required fields.

    Next Steps
    Evidence
    Creator Insights

    Advice

    Should be used with clinical history, examination, bronchoscopy, and arterial blood gas data to determine the full clinical picture.

    Management

    • 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

    As always, clinical judgment is paramount. Management decisions should not be made based solely on RADS.

    Formula

    Selection of the appropriate finding:

    Finding

    Score

    Normal

    0

    Increased interstitial markings

    1

    Ground glass opacification

    2

    Consolidation

    3

     RADS quadrants

    Instructions:

    1. Divide each lung on CT chest slice into quadrants as above.
    2. Select the worst (i.e., highest) possible score for each quadrant. Example: presence of a small area of consolidation in a quadrant yields a score of 3, even if the remainder of the quadrant is not consolidated.
    3. Add total RADS for each slice read, then divide by number of slices read per CT to obtain RADS per slice.

    Facts & Figures

    Interpretation:

    RADS 

    Risk

    >8 per slice

    12.7x increased risk of composite endpoint (pneumonia, acute lung injury/ARDS, and death)

     

    Evidence Appraisal

    The RADS tool was developed from an ovine study of 20 anesthetized sheep who were intubated, exposed to wood smoke and then underwent CT scan of the thorax at 6, 12, and 24 hours after exposure. The study raised questions of whether smoke inhalation from combustion of materials other than wood smoke behave in this way, if a normal CT would be sufficient to rule out significant injury, and direct comparison of the score to better established diagnostic tools such as fiberoptic bronchoscopy.

    Oh et al conducted a retrospective study of 43 patients, 25 with inhalation injury and 19 without, and found, by multiple logistic regression, that inhalation injury on bronchoscopy correlated with an 8.3-fold increase in a composite endpoint of pneumonia, ALI/ARDS, and death. Positive bronchoscopy in conjunction with RADS >8 was correlated with a 12.7-fold increase in the composite endpoints.

    We are not aware of any studies looking at interrater reliability of the scoring system.

    A prospective clinical trial is currently underway to help answer many of these questions. Preliminary clinical data from this Inhalation Severity Injury Scoring System (ISIS) Trial demonstrated a positive correlation between RADS and ventilator days.

    Literature

    Other References

    Research PaperWalker PF, Buehner MF, Wood LA, et al. Diagnosis and management of inhalation injury: an updated review. Crit Care. 2015;19:351. Research PaperEnkhbaatar P, Pruitt BA, Suman O, et al. Pathophysiology, research challenges, and clinical management of smoke inhalation injury. Lancet. 2016;388(10052):1437-1446.Research PaperPark MS, Cancio LC, Batchinsky AI, et al. Assessment of severity of ovine smoke inhalation injury by analysis of computed tomographic scans. J Trauma. 2003;55(3):417-27.Research PaperAugust DL, Foster K, Richey K, Gridley D, Peck M and Pressman M. Computerized Tomography Correlates with Ventilator Days in Inhalation Injury: Preliminary Data from the Inhalation Severity Injury Scoring System (ISIS) Trial. Society of Thoracic Radiology. March 16, 2014. Oral Presentation. Research PaperCioffi Jr WG, Rue 3rd LW, Graves TA, McManus WF, Mason Jr AD, Pruitt Jr BA. Prophylactic use of high-frequency percussive ventilation in patients with inhalation injury. Ann Surg. 1991;213:575–80. discussion 580–2.Research PaperPutman CE, Loke J, Matthay RA, Ravin CE. Radiographic manifestations of acute smoke inhalation. AJR Am J Roentgenol. 1977;129(5):865-70.
    Dr. John S. Oh

    About the Creator

    John S. Oh, MD, FACS, is a trauma critical care surgeon and director of surgical critical care at Penn State Hershey Medical Center. He served as chief of general surgery at the Walter Reed National Military Medical Center and director of the division for global surgery at the Uniformed Services University of the Health Sciences. Dr. Oh's primary research interests include combat casualty care, traumatic brain injury, and prehospital injury care.

    To view Dr. John S. Oh's publications, visit PubMed

    Content Contributors
    • Pujan H. Patel, MD
    About the Creator
    Dr. John S. Oh
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    Content Contributors
    • Pujan H. Patel, MD