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Abbreviated Injury Score (AIS) for Inhalation Injury

Calculators  Respiratory
The Abbreviated Injury Score (AIS) categorises the inhalation injury severity based on bronchoscopic findings.
Bronchoscopic findings
No bronchorrhea, edema, obstruction, erythema, or carbonaceous deposits 0
small or patchy areas of, bronchorrhea, erythema, bronchial obstruction, or carbonaceous deposits present 1
Moderate bronchorrhea, erythema, bronchial obstruction, or carbonaceous deposits present 2
Severe swelling with friableness, bronchorrhea or obstruction, copious carbonaceous deposits present 3
Mucosal sloughing, endoluminal obstruction, or necrosis present 4
Result:

Background

Measured Factor
Grade
Measured Factor Disease
  • The AIS may predicts the development of acute respiratory distress syndrome (ARDS)
  • the length of time on mechanical ventilation
  • prolonged stay in the intensive care unit
  • survival rate
Speciality
Pulmonologist
Body System
Respiratory
Measured Factor High Impact
  • Fluid resuscitation requirements
  • initial oxygenation
  • increased lung compliance
  • enhanced duration of mechanical ventilation
  • risk of mortality

Result Interpretation

Ranges Ranges
  • Critical Low: 0
  • Normal: 0
  • Normal Adult Male: 0
  • Normal Adult Female: 0
  • Normal Pediatric: 0
  • Normal Neonate Female: 0
  • Normal Geriatric Male: 0
  • Normal Geriatric Female: 0
Result High Conditions
  • Increase in mortality
  • impaired gas exchange
Test Limitations
The AIS criteria have not been compared with other bronchoscopic criteria. There is no universal consensus on diagnostic and grading criteria for inhalation injury. A multicenter prospective cohort study by the American Burn Association is currently underway, with the goal of developing a scoring system for inhalation injury based on clinical, radiographic, bronchoscopic, and biochemical parameters. Differences in the individual host inflammatory response may lead to a heterogeneous clinical presentation in this test. This test cannot effectively predict the requirement of high fluid resuscitation.

Studies

Study Validation 1
In this study, the authors evaluated whether bronchoscopic grading of injury clinically correlated with indices of gas exchange over the first 72 hours or predicted differences in hospitalization outcomes. A single-center retrospective review of all mechanically ventilated adults with suspected inhalation injury and thermal injury over an 18-month period was performed. All recorded bronchoscopy examinations were reviewed and categorized injury according to the published abbreviated injury score (AIS 0: no injury, 1: mild, 2: moderate, 3: severe, and 4: massive injury). Changes in oxygenation, airway pressures, chest radiograph findings, fluid administration, and early development of pneumonia and organ failure, by severity of inhalation injury was done according to the AIS. The results of the study demonstrate that the bronchoscopic grading of inhalation injury moderately correlates with early indices of impaired gas exchange in this cohort and may be a promising tool for staging lower airway injury.
References: 2
Study Validation 2
The purpose of this study was to assess whether the grade of mucosal INH severity was associated with various outcomes among adult burn patients.  A retrospective review of all patients requiring greater than or equal to 48 hours of mechanical ventilation who were admitted between January 1, 2007 and June 1, 2014 to an adult regional American Burn Association-verified burn center were evaluated. Bronchoscopy was performed on all subjects at burn center admission and grading of severity was documented using the grades 0 to 4 abbreviated injury score (AIS). Subjects with grade 1 or 2 injury formed the low-grade INH group, whereas those with grade 3 or 4 injury formed the high-grade INH group. The study indicates that the individual grades of the 0 to 4 AIS INH severity grading scale were not particularly robust in the prediction of various outcomes among a population of adult burn patients. However, clinically relevant trends toward worsened oxygenation over postburn days 0 to 3, longer duration of mechanical ventilation, and reduced ventilator-free days in association with more severe INH were identified when subjects were broadly stratified into low-grade (grades 1and 2) INH and high-grade (grades 3 and 4) INH
References: 3
Study Validation 3
In a prospective observational study, bronchoalveolar lavage fluid for both leukocyte differential and concentration of 28 cytokines, chemokines, and growth factors  was assessed. Results were then compared to the graded severity of inhalation injury as determined by Abbreviated Injury Score criteria (0, none; 1, mild; 2, moderate; 3, severe; 4, massive). Patients who presented with worse grades of inhalation injury had higher plasma levels of carboxyhemoglobin and enhanced airway neutrophilia. Patients with the most severe inhalation injuries also had a greater requirement for tracheostomy, longer time on the ventilator, and a prolonged stay in the intensive care unit.
References: 4
Study Additional 1
Multiple studies have demonstrated that inhalation injury is a graded phenomenon with severity correlating with outcome. The Abbreviated Injury Score grading scale for inhalation injury on bronchoscopy has been shown to correlate with an increase in mortality as well impaired gas exchange. It has been found that patients with more severe inhalation injury on initial bronchoscopy (grades 2, 3, 4) had worse survival rates than patients with lower scores (grades 0 or 1) (P = 0.03). It has also been noted that the highest-grade inhalation injuries were not necessarily associated with an increased fluid requirement.
References: 5
Study Additional 2
A study by Hassan et al.  on 105 patients admitted with inhalation injury assessed respiratory function by using the PaO2/FiO2 ratio from 0 to 192 h after injury. Their study showed a significant difference (P < 0.01) in PaO2/FiO2 ratios between patients who died (mean PaO2/FiO2 ratio 20.17) and those who survived (mean PaO2/FiO2 ratio 32.24). Ultimately, they propose to use PaO2/FiO2 ratio as a predictor of survival once the initial burn resuscitation has been completed and a full response to injury is able to be mounted. The study also found a significant increase (P < .01) in mortality with bronchoscopic
severity.
References: 6
Study Additional 3
Inhalation injury (INH) is present in one third of large burn injuries and increases oxygenation and fluid resuscitation requirements, incidences of pulmonary complications, risk for multiple organ dysfunction syndrome (MODS), and overall mortality. Previous studies have demonstrated inconsistent correlation between bronchoscopic evaluation and clinical outcomes. This study reviewed 161 patients admitted with a diagnosis of INH or underwent diagnostic bronchoscopy for suspected INH over a period of 8.5 years. One hundred one patients had concomitant burn injury and 60 had isolated INH. Seventeen patients had abbreviated injury score (AIS) 0, 81 patients had low-grade injury (AIS 1 and 2), and 63 patients had high-grade injury (AIS 3 and 4). Patients with high-grade INH had worse pulmonary dysfunction, worse oxygenation indices (P = 0.01) and plasma carboxyhemoglobin (COHgb; P < 0.01) on admission, increased fluid requirements (P < 0.01 at 24 hours; P = 0.04 at 48 hours), MODS (P = 0.04), pneumonia (P < 0.01), acute respiratory distress syndrome (P = 0.01 at 48 hours), fewer 28-day ventilator-free days (P < 0.01), greater ventilator dependence (P = 0.03), and longer length of stay (P < 0.01). Multivariate analyses demonstrated increased risk of MODS (P = 0.03), acute respiratory distress syndrome at 48 hours (P < 0.01), pneumonia (P = 0.01), prolonged ventilator dependence (P = 0.03), and a trend toward mortality (P = 0.08) with higher AIS groups.
References: 7

Authors

Frederick W. Endorf
MD
General surgeon, Mount Sinai School of Medicine, New York, NY, USA , Hennepin County Medical Center in Minneapolis and the American Burn Association
Research Interests: Burns, trauma, and reconstructive surgery , trained in general surgery, surgical critical care and burns
https://www.healthcare4ppl.com/physician/minnesota/st-paul/frederick-w-endorf-1063529881.html
Richard L. Gamelli
MD
Professor emeritus, Stritch School of Medicine at Loyola University Chicago
Research Interests: Former director of the Burn and Shock Trauma Research Institute, chairman of the department of surgery, and chief of the burn center at Loyola University Medical Center
Published over 175 peer-reviewed manuscripts and abstracts, written 30 book chapters, and edited 10 books

References

  1. Endorf FW, Gamelli RL. Inhalation injury, pulmonary perturbations, and fluid resuscitation. J Burn Care Res. 2007;28(1):80-83.
  2. Mosier MJ, Pham TN, Park DR, Simmons J, Klein MB, Gibran NS. Predictive value of bronchoscopy in assessing the severity of inhalation injury. J Burn Care Res. 2012 Jan-Feb;33(1):65-73.
  3. Spano S, Hanna S, Li Z, Wood D, Cartotto R. Does Bronchoscopic Evaluation of Inhalation Injury Severity Predict Outcome? J Burn Care Res. 2016 Jan-Feb;37(1):1-11.
  4. Albright JM, Davis CS, Bird MD, Ramirez L, Kim H, Burnham EL, Gamelli RL, Kovacs EJ. The acute pulmonary inflammatory response to the graded severity of smoke inhalation injury. Crit Care Med. 2012 ;40(4):1113-21.
  5. Walker PF, Buehner MF, Wood LA, et al. Diagnosis and management of inhalation injury: an updated review. Crit Care. 2015;19:351.
  6. Hassan Z, Wong JK, Bush J, et al. Assessing the severity of inhalation injuries in adults. Burns. 2010;36(2):212-216.
  7. Sutton T, Lenk I, Conrad P, Halerz M, Mosier M. Severity of Inhalation Injury is Predictive of Alterations in Gas Exchange and Worsened Clinical Outcomes. J Burn Care Res. 2017 Nov/Dec;38(6):390-395.