冷却疗法对湿热环境下Ⅱ度烫伤大鼠的心率和平均动脉压的影响

目的 观察湿热环境下大鼠浅Ⅱ度烫伤创面即刻施行冷疗后心率(HR)及平均动脉压(MAP)的改变,并评价冷疗敷料的降温效果。方法 将24只Wistar大鼠随机分成4组,即常温常湿组、常温常湿冷疗组、湿热组和湿热冷疗组,每组6只。制作浅Ⅱ度烫伤模型后分别采取不同的干预条件,常温环境的实验条件为干球温度(Tdb)(26.33±1.29)℃、相对湿度(rh)(71.05±4.57)%,湿热环境的实验条件为Tdb(35.33±0.35)℃,rh(70.81±1.38)%。常温常湿组和湿热组不给予冷疗降温,常温常湿冷疗组和湿热冷疗组给予腹部冷疗敷料降温,暴露时间均为120 min。连续监测HR、MAP,每20 min记录1次。结果 湿热组比常温常湿组、湿热冷疗组比常温常湿冷疗组MAP无差异(P>0.05),湿热冷疗组比湿热组、常温常湿冷疗组比常温常湿组MAP无差异(P>0.05)。与常温相比,湿热环境使HR总体趋于增加(P=0.003),与对照组比较,冷疗使HR降低(P=0.002);4组组内7个不同时点HR差异无显著性意义(P>0.05);在65、85、105和125 min时点,湿热组比常温常湿组、湿热冷疗组比常温常湿冷疗组HR高,在5、25、45和85 min时点,与对照组相比,冷疗降低了HR。结论 在湿热环境下,腹部冷疗敷料降温对大鼠MAP无影响,但却有效降低了大鼠HR,阻止了热损伤的进程。

Effect of cooling therapy on the heart rate and mean arterial pressure of rats with the second-degree scald burn in hot and humid environment

Objective To observe the changes of heart rate (HR) and mean arterial pressure(MAP)after immediate cooling therapy (ICT) in rats with superficial second-degree scald burn in hot and humid environment, and assess the effect of the cooling dressing materials. Methods Twenty-four Wistar rats were randomized equally into 4 groups including normal temperature control (NTC) group, normal temperature cooling therapy (NCT) group, hot and humid control (HHC) group and hot and humid cooling therapy (HCT) group. Different interventions were applied as indicated in the rats with superficial second-degree scald burn, with the dry bulb temperature(Tdb) at 26.33±1.29 ℃ and relative humidity (rh) of 71.05%±4.57 % for two normal temperature groups, and Tdb at 35.33±0.35 ℃ and rh of 70.81%±1.38% for the two hot and humid groups. The exposure time was 120 min in NCT and HCT groups, and the HR and MAP were measured every 20 min. Results MAP is not influenced by environmental temperature and the cooling therapy (P>0.05), whereas HR was higher in HHC than in NTC group and also in HCT than in NCT group (P=0.003), lower in HCT and NCT groups than in HHC and NTC groups (P=0.002), respectively. HR did not undergo any significant changes during the observation in the 4 groups (P>0.05). HR was higher in HHC and HCT than in NTC and NCT groups at 65, 85, 105 and 125 min after the burns, but compared with the two control groups, cooling therapy decreased HR at 5, 25, 45 and 85 min. Conclusion Cooling therapy does not affect MAP but efficiently decreases HR, which may prevent further heat injury.