摘要目的 探讨复苏后早期经食道快速诱导低温对猪心肺复苏后肠黏膜损伤的影响.方法 国产健康雄性白猪27头,体质量(36±2)kg.采用随机数字表法分为3组(每组n=9):常温组(NT组)、体表降温组(SC组)与食道降温组(EC组).采用电刺激法诱发室颤8 min,心肺复苏5 min,制备心肺复苏猪模型.自主循环恢复(ROSC)后5 min时,EC组与SC组外接冰毯仪,分别经食道降温导管与体表冰毯进行降温,目标温度33℃,持续至ROSC后24 h,再以1℃/h复温5h.NT组全程维持正常体温(38.0±0.5℃).ROSC后30 h内动态监测核心体温,并于ROSC后3、6、12、24与30 h时,应用酶联免疫吸附试验法(ELISA)检测血清肠型脂肪酸结合蛋白(IFABP)的含量与二胺氧化酶(DAO)的活性.ROSC后30 h时处死猪,取小肠组织,应用ELISA法检测肿瘤坏死因子-α (TNF-α)与白细胞介素-6(IL-6)的含量,原位末端标记法检测细胞凋亡,免疫组织化学法检测半胱氨酸天冬氨酸蛋白酶-3(caspase-3)的蛋白表达水平.结果 EC组降温速率和达标时长均显著优于SC组(2.8℃/h vs.1.5℃/h,102 min vs.185 min,均P＜0.05).与NT组相比,EC组在ROSC后3h、SC组在ROSC后6h的IFABP含量与DAO活性均降低(均P＜0.05).与SC组相比,EC组在ROSC后6 h IFABP含量和在ROSC后12h DAO活性均下降[IFABP(pg/ml):6 h为(710±32)vs.(777±52),12h为(870±49) vs.(960±64),24h为(1 022±65) vs.(1 143±63),30h为(882±71) vs.(1 006±45);DAO(U/ml):12h为(39.9±1.9)vs.(43.4±3.2),24 h为(30.6±2.4) vs.(34.0±3.1),30 h为(26.1±2.7)vs.(29.4±2.2),均P＜0.05].与NT组相比,EC组与SC组TNF-α、IL-6含量减少,且凋亡指数、caspase-3蛋白表达均降低(均P＜0.05).与SC组相比,EC组炎症反应与细胞凋亡进一步减轻[TNF-α(pg/mL):(721±94)vs.(922±125);IL-6(pg/mL):(454±69) vs.(697±132);细胞凋亡指数(％):(62±2.6)vs.(12.8±3.0);caspase-3 (IOD):(8.9±1.6) vs.(1 5.9±1.9),均P＜0.05].结论 经食道可以快速诱导低温,其效果优于传统的体表降温并产生更好的ROSC后肠保护效应,其机制可能与抑制炎症反应、细胞凋亡等有关.

abstractsObjective To investigate the effects of rapid hypothermia induced via esophagus on intestinal mucous injury in early stage after cardiopulmonary resuscitation (CPR) in a swine model of cardiac arrest.Methods Twenty-seven male domestic pigs weighing (36±2)kg were utilized.The animals were randomly crandom number divided into 3 groups (n=9 in each):normothermia group (NT group),surface cooling group (SC group),and esophageal cooling group (EC group).The pig model was established by 8 mins of untreated ventricular fibrillation and then 5 mins of CPR.At 5 mins after restoration of spontaneous circulation (ROSC),therapeutic hypothermia was applied by either an esophageal cooling device in the EC group or a surface cooling blanket in the SC group to reach a targeted temperature of 33 ℃ maintained for 24 h after ROSC,and then followed by warming up in a rate of 1 ℃ / hr for 5 hrs.A normal temperature of (38.0±0.5)℃ was maintained throughout the experiment in the NT group.The core temperature was continuously monitored during a period of 30 h after ROSC.At 3 h,6 h,12 h,24 h and 30 h after ROSC,intestinal fatty acid binding protein (IFABP) content and diamine oxidase (DAO) activity in serum were measured by ELISA.At 30 h after ROSC,the pigs were sacrificed,and then intestinal tissue was rapidly obtained for the determination of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) contents by ELISA,cell apoptosis by TUNEL,and caspase-3 expression by immunohistochemistry.Results The rate of temperature decrease was 2.8 ℃/h and the time required for target temperature was 102 min in the EC group,while the rate of temperature decrease was 1.5 /h and the time consumed for target temperature was 185 mins in the SC group,which suggested the efficacy of cooling was significantly better in the EC group than that in the SC group (both P＜0.05).Compared with the NT group,serum IFABP content and DAO activity were significantly decreased at 3 hrs after ROSC in the EC group and at 6 hrs after ROSC in the SC group.Compared with the SC group,serum IFABP content at 6 hrs after ROSC and DAO activity at 12 h after ROSC were significantly decreased in the EC group IFABP (pg/mL):(710±32) vs.(777±52) at 6 h,(870±49) vs.(960±64) at 12 h,(1 022±65)vs.(1 143±63) at 24 h,(882±71) vs.(1 006±45) at 30 h DAO (U/mL):(39.9±1.9) vs.(43.4±3.2) at 12 h,(30.6±2.4) vs.(34.0±3.1) at 24 h,(26.1±2.7) vs.(29.4±2.2) at 30 h,all P＜0.05.In the intestinal tissue,TNF-α and IL-6 contents were significantly reduced,and cell apoptosis index and caspase-3 expression were significantly decreased in the SC and EC groups compared with the NT group.Additionally,inflammatory response and cell apoptosis in intestinal tissue were further significantly lesser in the EC group compared with the SC group TNF-α (pg/mL):(721±94) vs.(922±125);IL-6(pg/mL):(454±69) vs.(697±132);Apoptotic index(％):(6.2±2.6)vs.(12.8±3.0);caspase-3 expression (IOD):(8.9±1.6) vs.(15.9±1.9),all P＜0.05.Conclusions In a swine model of cardiac arrest,rapid hypothermia could be successfully induced via esophagus and consequently produced a greater protective effect on post-resuscitation intestinal injury compared with the conventional surface cooling.The protective mechanisms are associated with the inhibition of inflammatory response and cell apoptosis.