| Objective: To investigate the effect of hypothermia liquid resuscitation on the recovery of hemorrhagic shock rats under high temperature and high humidity,and the effect of urapidil combined with hypothermia liquid resuscitation on the recovery of hemorrhagic shock rats under high temperature and high humidity.Methods: 72 SPF male Sprague-Dawley（SD）rats with body weight of（280 ± 20）g were randomly divided into 6 groups（12 rats in each group）: normal temperature constant humidity shock model group（group S1）,high temperature and high humidity shock model group（group S2）,high temperature and high humidity shock hypothermia liquid group（group H2）,high temperature and high humidity shock urapidil+hypothermia liquid resuscitation（group H3）,high temperature and high humidity shock urapidil+normal temperature liquid group（group H4）[the temperature of hypothermia liquid was maintained at（4 ± 1）℃,the temperature of room temperature liquid shall be maintained at（23±1）℃].The conditions for high temperature and high humidity environment setting are dry bulb temperature of（37±0.5）℃,relative humidity of（80±5）%,and total exposure time of 150 min.In the first part,hemorrhagic shock was made under normal temperature and humidity（temperature:（25±0.5）℃,relative humidity:50%）and high temperature and humidity（temperature:（37 ± 0.5）℃,relative humidity:（80 ± 5）%）.Rats were allowed to move freely for 30 min in the required environment.The model of hemorrhagic shock was prepared by modified wigger’s method after successful anesthesia.The mean arterial pressure was 30-40 mm Hg（1 mm Hg = 0.133 k Pa）by femoral artery exsanguination,and the blood pressure was kept stable for 10 min,which indicated that the model of hemorrhagic shock was successfully prepared.After successful modeling,arterial blood was collected to detect the corresponding indicators,including serum lactic acid value,concentration of tumor necrosis factor alpha（TNF-α）,interleukin-6（IL-6）and C-reactive protein（CRP）.Rectal temperatures were recorded in rats every 20 minutes.In the second and third part,the rats were placed in a high temperature and high humidity simulation chamber[temperature（37±0.5）℃,relative humidity（80± 5）%] for 30 min.After anesthesia,the hemorrhagic shock model was prepared by the modified wigger’s method.The mean arterial pressure was 30-40 mm Hg（1 mm Hg = 0.133 k Pa）after exsanguination from the femoral artery.The model of hemorrhagic shock was prepared after the blood pressure was kept stable for 10 minutes.The rats in each group were reinfused with autologous blood after the model of hemorrhagic shock was successful.After different fluids were infused into each group,arterial blood was collected at 30 min,60 min and 90 min after the infusion.The changes of rectal temperature were recorded,and the serum lactic acid value,TNF-α,IL-6 and CRP concentrations were measured.Results: Part 1: After entering high temperature and humidity environment,the rectal body temperature of rats increased rapidly from 37.0 ℃ to 40.2 ℃.In normal temperature group,the body temperature fluctuated between 36 ℃ and 38 ℃.At 20 min,30 min,40 min,50 min and 60 min,the difference of body temperature between the two groups was significant（P<0.05）.2.The serum lactic acid,TNF-α,IL-6 and CRP levels were measured by arterial blood in hemorrhagic shock group.There was no significant difference between the two groups（P>0.05）.The serum TNF-α,IL-6 and CRP levels were significantly increased in hypothermia shock group and normothermic shock group（P<0.05）.Part 2: Rats with hemorrhagic shock exposed to high temperature and humidity showed rapid increase of body temperature in each group.HS model was successful.After fluid resuscitation: 1.rectal temperature of rats in hypothermia liquid group showed a decreasing trend.However,the body temperature of rats in the normal temperature liquid group still increased.2.There was no significant difference in serum lactic acid between groups after resuscitation（P>0.05）,but there was a tendency to decrease with time.3.The serum levels of IL-6 and C-reactive protein（CRP）in the hypothermia liquid group were significantly lower than those in the normal temperature liquid group at90 min,120 min and 150 min after heat exposure（P<0.05）,and the serum levels of TNF-α in the hypothermia liquid group at 150 min after heat exposure（P<0.05）.Part 3: 1.The rectal temperature of rats in groups H2,H3 and H4 showed a decreasing trend.However,the decreasing tendency of H3 group was more obvious than that of H2 and H4 groups.2.After resuscitation,there was no significant difference between the groups（P>0.05）,but there was a decreasing trend with the prolongation of time.3.The concentration of IL-6 in serum of H3 group was 120 min,the CRP level was 120 min and 150 min were lower than that of H2group（P<0.05）,and the concentration of TNF-α was 150 min（P<0.05）.The serum levels of TNF-α and CRP in H3 group were significantly lower than those in H4 group（P<0.05）at 90 min,120 min and 150 min.The serum levels of IL-6 in H3 group were lower than those in H4 group（P<0.05）at 120 min and 150 min.Conclusion: 1.High temperature and high humidity can rapidly increase the body temperature of rats,and heat stress occurs in high temperature and high humidity environment.After hemorrhagic shock,the reaction of stress and inflammation is more serious.2.The application of hypothermia liquid resuscitation in high temperature and high humidity can reduce the body temperature at early stage,inhibit the release of inflammatory mediator such as TNF-α、IL-6,and improve the resuscitation effect of hemorrhagic shock in rats under high temperature and high humidity.3.The compound hypothermia liquid can increase the body temperature,inhibit the release of inflammatory mediator such as TNF-α 、 IL-6,allow the low pressure resuscitation and the hypothermia liquid resuscitation to play a synergistic role,and have better effect on the resuscitation of hemorrhagic shock in high temperature and high humidity environment. |
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