title: Circulational heat dissipation of upper airway: Canine model of inhalational thermal injury.
abstract: BACKGROUND
  The upper airway has powerful heat-absorbing ability, in which the blood circulation may play an important role.
  
  
  OBJECTIVE
  This study aimed to explore the circulational heat-dissipating ability, and to investigate the contribution of blood circulation to the heat-absorbing ability of upper airway.
  
  
  METHODS
  18 adult, male Beagle dogs were divided into three groups to inhale thermal dry air of 70-80°C, 150-160°C or 310-320°C for 20min. Blood temperatures and blood flow rates of bilateral common jugular veins (CJVs) were measured. Dogs' breathing rates and air temperatures in middle trachea were also measured. According to the formula "Q=c·m·ΔT", the heat dissipated by blood (Q-blood) and the heat release by air (Q-air) were calculated out. The contribution of circulational heat dissipation to the heat-absorbing ability of upper airway was defined as "C-blood".
  
  
  RESULTS
  The blood temperature rise of CJV was 2.24±0.60°C. The blood flow rate of CJV was 44.5±5.9ml/min. The air temperature in middle trachea was 63.5±18.9°C. The mean breathing rate was 51.8±7.5/min. The calculated "Q-blood" and "Q-air" were 13197.3±4408.6J and 33540.2±24578.7J, and the "C-blood" was 55.2±25.0% (21.7-88.8%).
  
  
  CONCLUSIONS
  Circulational heat dissipation plays an important role in the heat-absorbing process of upper airway when inhaled air is less than 160°C. However, for air higher than 160°C, some other mechanism might be dominant in the upper airway's heat-absorbing ability.
authors.affiliation: Burn Department, 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: Chun-Quan
authors.initials: CQ
authors.lastname: Wen
authors.forename: Fang-gang
authors.initials: FG
authors.lastname: Ning
authors.forename: Guo-an
authors.initials: GA
authors.lastname: Zhang
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D002059:Burns, Inhalation / Q000503:physiopathology*; D004195:Disease Models, Animal; D004285:Dogs; D007601:Jugular Veins / Q000502:physiology; D008297:Male; D012039:Regional Blood Flow / Q000502:physiology; D056152:Respiratory Rate / Q000502:physiology*; D014132:Trachea / Q000503:physiopathology*
keywords: Blood circulation; Canine model; Circulational heat dissipation; Contribution; Inhalation injury; Inhalational thermal injury