title: Measuring surface temperature and grading pathological changes of airway tissue in a canine model of inhalational thermal injury.
abstract: BACKGROUND
  Airway tissue shows unexpected invulnerability to heated air. The mechanisms of this phenomenon are open to debate.
  
  
  OBJECTIVE
  This study was designed to measure the surface temperatures at different locations of the airway, and to explore the relationship between the tissue's surface temperature and injury severity.
  
  
  METHODS
  Twenty dogs were randomly divided into four groups, including three experimental groups (six dogs in each) to inhale heated air at 70-80 °C (group I), 150-160 °C (group II) and 310-320 °C (group III) and a control group (two dogs, only for histological observation). Injury time was 20 min. Mucosal surface temperatures of the epiglottis (point A), cricoid cartilage (point B) and lower trachea (point C) were measured. Dogs in group I-III were divided into three subgroups (two in each), to be assayed at 12, 24 and 36 h after injury, respectively. For each dog, four tissue parts (epiglottis, larynx, lower trachea and terminal bronchiole) were microscopically observed and graded according to an original pathological scoring system (score range: 0-27).
  
  
  RESULTS
  Surface temperatures of the airway mucosa increased slowly to 40.60±3.29 °C, and the highest peak temperature was 48.3 °C (group III, point A). The pathological score of burned tissues was 4.12±4.94 (0.0-18.0), suggesting slight to moderate injuries. Air temperature and airway location both influenced mucosal temperature and pathological scores very significantly, and there was a very significant positive correlation between tissue temperature and injury severity.
  
  
  CONCLUSIONS
  Compared to the inhalational air hyperthermia, airway surface temperature was much lower, but was still positively correlated with thermal injury severity.
authors.affiliation: Department of Burns, Beijing Jishuitan Hospital, No. 31 Xinjiekou East Street, Xicheng District, Beijing 100035, PR China.
authors.forename: Ran
authors.initials: R
authors.lastname: Zhao
authors.forename: La-na
authors.initials: LN
authors.lastname: Di
authors.forename: Xiao-zhuo
authors.initials: XZ
authors.lastname: Zhao
authors.forename: Cheng
authors.initials: C
authors.lastname: Wang
authors.forename: Guo-an
authors.initials: GA
authors.lastname: Zhang
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001831:Body Temperature / Q000502:physiology; D002059:Burns, Inhalation / Q000473:pathology / Q000503:physiopathology*; D004195:Disease Models, Animal; D004285:Dogs; D015601:Injury Severity Score; D011897:Random Allocation; D020545:Respiratory Mucosa / Q000502:physiology; D056152:Respiratory Rate / Q000502:physiology; D012137:Respiratory System / Q000473:pathology / Q000503:physiopathology*; D013696:Temperature