组胺对肠黏膜屏障的保护作用

肠黏膜屏障是构成机体内外环境的一种重要屏障,肠黏膜屏障主要由机械屏障、免疫屏障、化学屏障等组成,对防止病原微生物从肠黏膜侵入机体有着非常重要的作用。缺血缺氧、严重创伤、肠道感染、休克等情况均可引起肠黏膜屏障损伤。肠道内细菌及毒素均可突破肠黏膜屏障引起细菌移位、肠源性脓毒症等。研究表明,肠道给予小剂量组胺有保护肠黏膜屏障和抑制肠道细菌移位的作用。     

甲状腺素对缺血-再灌注肠黏膜屏障功能的保护作用

目的：探讨肠缺血-再灌注24h时甲状腺素代谢异常和肠黏膜屏障破坏之间的关系，阐明外源性甲状腺素对肠黏膜屏障功能的保护作用。方法：将39只Wistar大鼠随机分为4组：假手术组（S，n=12）；肠缺血-再灌注组（G，n=8）；肠缺血-再灌注＋生理盐水组（N，n=9）；肠缺血-再灌注＋甲状腺素组（T，n=10）。利用肠系膜上动脉夹闭法制作大鼠肠缺血-再灌注模型，并补充外源性甲状腺素。24h后测定外周血游离甲状腺素、促甲状腺素、磷酸肌酸激酶和门静脉血内毒素水平，同时做肠黏膜病理形态学检查。结果：再灌注24h后，G组和N组的血清甲状腺素水平明显低于S组、T组，两者有显著差异（P〈0.01），但T组和S组之间无显著差异（P〉0．05）；磷酸肌酸激酶水平G组和～组明显高于S组、T组，（P〈0．01），但T组和S组之间无显著差异（P〉0．05）；门静脉血内毒素水平G组和N组明显高于S组、T组，（P〈0．01）；肠黏膜组织结构以G组和N组破坏最为严重，T组变化轻微。结论：肠缺血-再灌注时，肠黏膜屏障功能受到破坏；外周血甲状腺素代谢异常，血清甲状腺素水平降低；补充外源性甲状腺素可以保护肠缺血-再灌注时肠黏膜屏障功能。     

急性胃肠黏膜损伤:病理生理与治疗

急性胃肠黏膜损伤在危重症患者并非少见,往往与出血、感染、休克、腹腔高压(intra-abdominal hypertension,IAH)等病理过程相关。作为机体的一道重要防线,肠黏膜具有机械屏障、免疫屏障等重要生理作用,是机体内外环境的重要分水岭。肠黏膜也是缺血敏感的器官,其解剖和生理上的特点,使肠道作为休克时首先"跌倒"和最后"恢复"的器官,常常以自身黏膜损伤为代价,也是导致缺血再灌注损伤后多器官功能损伤的使动器官。但是,肠屏障功能在临床判断与目标指导性治疗上与其他器官功能障碍的治疗策略相比却明显不足。基于病理、生理特点认识严重疾病状态下的肠黏膜损伤,将有助于更好的理解和维护肠黏膜屏障的解剖与功能的完整性。     

大鼠休克复苏后肠黏膜屏障特点的探讨

目的 探讨失血性休克肠缺血．再灌注损伤后黏膜屏障的形态学、功能与重建的特点。方法 制作大鼠失血性休克模型，于复苏后0、1、3、6、12、24h时间段活杀并进行光镜和电镜下肠黏膜组织形态学观察、内毒素含量及尿液乳果糖，甘露醇比值的测定。结果 肠黏膜主要表现为凋亡和坏死两种损伤形式，大部分肠黏膜于6h重建，12h结构基本恢复正常，肠杯状细胞数在各组呈下降趋势；内毒素和乳果糖，甘露醇比值在6h达高峰。结论 失血性休克后肠黏膜屏障早期受累，但同时具有快速重建能力；屏障功能的恢复滞后于形态学重建。     

弥漫性脑损伤后大鼠肠黏膜上皮细胞的凋亡和核因子-κB的表达

目的 观察弥漫性脑损伤后大鼠肠黏膜上皮细胞凋亡以及核因子-κB（NF-κB）表达的动态变化，探讨两者在肠黏膜屏障功能障碍中的作用。方法 采用Marmarou模型致大鼠重型弥漫性脑损伤，150只雄性Wistar大鼠随机分成对照组和伤后1、2、4、8、12、24、48、72、168h组，共10组，利用免疫组化技术检测NF-κB在不同时相组的表达，采用原位末端标记（TUNEL）法计数不同时相组凋亡细胞。结果 致伤组NF-κB表达的积分光密度均显著大于对照组（P〈0．01）；伤后1h凋亡细胞数量即开始增加，于伤后12h达到峰值后逐渐下降，但直到168h均较对照组明显升高（P〈0.01）。结论 弥漫性脑损伤后激活NF-κB。肠黏膜上皮细胞凋亡增加，两者在肠黏膜屏障功能障碍发生中可能起重要作用。     

肠黏膜屏障损伤的诊断和治疗研究进展

肠黏膜是机体一处最大的黏膜表面,成年人肠黏膜的表面积可达300m^2以上。它不但是营养物质消化吸收的重要场所,同时也是病原微生物及毒素侵入机体的主要门户。在严重创伤、全身及肠道严重感染、缺血及缺血一再灌注、营养障碍及全胃肠外营养（total parentered nutrition,TPN）、肠道内微生态失调、休克等情况下,可引起肠黏膜屏障损伤。轻者可引起细菌易位、肠源性脓毒血症,重者可导致全身炎反应综合征（SIRS）,一旦转变为感染中毒性休克或多器官功能衰竭综合征（MODS）,则治疗困难,预后恶劣,甚至引起死亡。现就近几年肠黏膜屏障损伤诊断与治疗方面的研究进展综述如下。     

肠道缺血再灌注损伤后肠道细菌移位研究进展

肠道急性缺血性疾病治疗后通常会发生缺血再灌注损伤,损伤后可引发肠屏障功能障碍,引起细菌和内毒素的移位,当机体应激反应过度或失调时,寄生于肠道内的微生物或其释放的内毒素,通过某种途径越过肠黏膜屏障,     

重症急性胰腺炎肠黏膜屏障功能障碍的研究进展

重症急性胰腺炎(SAP)是临床上最常见的急腹症之一,病死率高,可伴有多脏器损伤,肠道是最晚修复的损伤器官。肠道不仅可以吸收营养物质,也可以抵御外来有害物质,肠黏膜屏障可阻断肠腔和人体内部组织,有效防止肠道外来有害物质进入血液循环,维持正常的肠道功能,降低肠源性感染的可能性。SAP可引起肠道缺血和缺氧,机体炎症反应也可破坏肠黏膜屏障,引起肠道细菌移位并损伤肠道功能,加速SAP的进展。本文检索大量SAP相关文献进行分析归纳,总结了SAP肠黏膜屏障功能损伤的机制,以期为SAP肠道损伤患者的临床诊疗提供参考和指导。     

慢性肝病与肠黏膜屏障作用异常

在慢性肝病病人中,肝功能异常常引起胃肠道功能障碍,包括肠黏膜屏障功能异常,而改善肠黏膜屏障功能,亦可促进肝脏疾病的恢复。本文就肝损伤时肠黏膜屏障的变化以及肠黏膜屏障功能异常对肝脏疾病发展的影响进行了分析。     

瓜氨酸在脓毒症肠功能障碍临床意义与应用

正常肠黏膜可发挥其屏障功能,对肠腔的细菌、毒素吸收充分阻断,而机体在脓毒症中,由于缺血再灌注损伤、大量炎症介质释放、肠道微生态失衡均造成肠黏膜的不断损伤,进而导致肠道毒素、细菌、代谢产物移位,直接造成脓毒症加重,     

Current status of cerebral protection with mild-to-moderate hypothermia after traumatic brain injury

PURPOSE OF REVIEW: The aim of this article is to review the current status of protective effects of mild-to-moderate hypothermia on traumatic brain injury. RECENT FINDINGS: More than 30 clinical studies have reported effects of therapeutic hypothermia on outcome of traumatic brain injury and cerebral ischemia. Only one clinical trial of short-term mild hypothermia did not show any effect in patients with severe traumatic brain injury. Long-term mild hypothermia may be useful for severe traumatic brain-injured patients. SUMMARY: Mild-to-moderate hypothermia plays a significant role in cerebral protection after traumatic brain injury.     

血小板活化因子与颅脑损伤后应激性胃黏膜病变

血小板活化因子(platelet-activating factor,PAF)是体内一种具有多种生物活性的内源性磷脂介质,对多种组织器官具有广泛效应。PAF与脑损伤后应激性胃黏膜病变有密切关系。PAF加重脑的原发性和继发性损伤,阻碍脑微循环,加剧脑水肿,加重缺血/再灌注损伤与神经细胞凋亡；同时减少胃黏膜血流量,促进粒细胞聚集并释放炎性介质,使Ca~(2 )与氧自由基释放增加,胃酸分泌增多,导致脑损伤后应激性胃溃疡发生与加重。PAF受体拮抗药对应激性胃黏膜有保护作用并减轻损伤,改善预后且减轻其并发症。     

Regional ischemia after head injury

PURPOSE OF REVIEW: To examine the evidence of regional cerebral ischemia after traumatic brain injury. RECENT FINDINGS: This review describes the mechanisms responsible for secondary brain injury and the similarities between traumatic and ischemic neuronal cell death. Cerebral ischemia is defined, and the difficulties of quantifying the burden of cerebral ischemia in the context of clinical head injury are presented. Recent clinical data obtained from monitoring brain tissue oxygenation, tissue metabolites using microdialysis, and cerebral blood flow, blood volume, oxygen metabolism, and oxygen extraction fraction using oxygen-15 positron emission tomography are discussed. These data highlight that significant episodes of regional ischemia occur within the acute phase after injury and are associated with poor outcome. Although various monitoring tools are capable of detecting significant episodes of regional ischemia, each of the currently available techniques is limited in its clinical application. SUMMARY: There is increasing evidence to suggest that a small but significant volume of brain tissue is at risk of ischemic injury after trauma. Future studies should examine the pathophysiology underlying such ischemia and how monitoring techniques can be used to direct appropriate therapy and influence outcome.     

重型创伤性颅脑损伤患者自发性过度通气的研究进展

预防和减轻继发性脑损伤是重型创伤性颅脑损伤（sTBI）患者重症监护治疗过程中的重点和难点。诱导性过度通气（IHV）可通过减少脑血容量快速降低颅内压,但由于脑血管收缩带来的脑血流减少会加重脑组织的缺血缺氧,目前已不再推荐用于sTBI患者的常规治疗。与此同时,以不同程度的低碳酸血症为特征的自发性过度通气（SHV）在急性创伤性脑损伤患者中较为常见,且由于与患者的神经功能不良转归具有明显的相关性,近年来逐渐受到重视。本文从流行病学、病理生理学效应、临床预后及干预措施等角度对SHV在sTBI中的研究现状进行综述,以期提高重症医师的认知水平,进而重视并推动相关临床及基础研究的开展。     

肠道微生物群组在创伤性脑损伤后遗症的作用机制

创伤性脑损伤(TBI)是威胁人类健康的主要问题之一,因其可造成人类认知能力下降、癫痫发作、运动功能受损和人格改变等,而广受人类关注,而颅脑损伤后体内微生物变化及其对脑外伤后遗症的影响机制研究还不透彻.本文回顾颅脑损伤后人体内肠道微生物的变化及其对脑外伤后遗症的影响,包括血脑屏障的通透性增加、脑肠轴的变化等,并探讨可能的...     

关注颅脑创伤

简要复习了有关颅脑创伤(TB I)的基础与临床的一些近况,对其流行病学、病理生理、诊断新法、预后及救治作了简述,其中对脑缺血、钙超载、脑肿胀、轴索损伤等影响预后的因素作了介绍。     

Hyperoxia: good or bad for the injured brain?

PURPOSE OF REVIEW: For decades it was assumed that cerebral ischemia was a major cause of secondary brain injury in traumatic brain injury, and management focused on improving cerebral perfusion and blood flow. Following the observation of mitochondrial dysfunction in traumatic brain injury and the widespread use of brain tissue oxygen tension (P(br)O(2) monitoring, however, recent work has focused on the use of hyperoxia to reduce the impact of traumatic brain injury. RECENT FINDINGS: Previous work on normobaric hyperoxia utilized very indirect measures of cerebral oxygen metabolism (intracranial pressure, brain oxygen tension and microdialysis) as outcome variables. Interpretation of these measures is controversial, making it difficult to determine the impact of hyperoxia. A recent study, however, utilized positron emission tomography to study the impact of hyperoxia on patients with acute severe traumatic brain injury and found no improvement on cerebral metabolic rate for oxygen with this intervention. SUMMARY: Despite suggestive data from microdialysis studies, direct measurement of the ability of the brain to utilize oxygen indicates that hyperoxia does not increase oxygen utilization. This, combined with the real risk of oxygen toxicity, suggests that routine clinical use is not appropriate at this time and should await appropriate prospective outcome studies.     

Traumatic brain injury: the silent epidemic.

It is difficult to accurately determine the number of people affected annually by the devastating effects of traumatic brain injury. It is clear, however, that the impact of traumatic brain injury exceeds the financial cost of acute health care. The long-term outcome of patients with traumatic brain injury has been targeted specifically for improvement during this decade. The initial brain injury--known as the primary injury--may occur in one area of the brain (focal injury) or may affect the entire brain (diffuse injury). The outcome depends on many factors, including the severity of the brain injury and the effectiveness of the interventions received. Accurate assessment of the scope of the problem would be improved by the development of a national database and the standardization of assessment practices. Critical care nurses can contribute skill and knowledge in the care of patients with traumatic brain injury and in efforts to prevent the accidents and violence that cause traumatic brain injury.     

Peritoneal lavage with oxygenated perfluorochemical preserves intestinal mucosal barrier function after ischemia-reperfusion and ameliorates lung injury

OBJECTIVE: To evaluate the effect of peritoneal lavage with an oxygenated perfluorochemical (PFC) on intestinal ischemia-reperfusion injury (IIR), we assessed intestinal barrier function in terms of bacterial translocation and endotoxemia, morphologic changes, and changes of intestinal luminal pH in rats subjected to IIR. We also examined lung injury after IIR to test the effect of oxygenated PFC lavage on remote organ failure. DESIGN: Prospective, randomized, and controlled animal study. SETTING: Laboratory of a university hospital. SUBJECT: Male Sprague-Dawley rats. INTERVENTIONS: Rats were subjected to ischemia by clipping the superior mesenteric artery. Reperfusion was achieved by release of the clip. Lavage of the abdominal cavity was performed by inflow and outflow of oxygenated PFC solution during ischemia. RESULTS: Rats undergoing peritoneal lavage with oxygenated PFC (PFC group) showed significantly better survival after IIR. The frequency of bacterial translocation and the endotoxin concentration in superior mesenteric venous blood were significantly lower in the PFC group. Luminal acidosis also was alleviated in the PFC group. Furthermore, PFC lavage preserved the intestinal mucosal architecture and inhibited interstitial edema and infiltration of inflammatory cells in the lungs. CONCLUSION: We conclude that peritoneal lavage with oxygenated PFC protects the intestinal mucosa and maintains mucosal barrier function after IIR. Preservation of the intestinal mucosa ameliorates lung injury after IIR.     

CT灌注成像对颅脑损伤术后脑微循环障碍的早期诊断价值

目的探讨重型颅脑损伤术后CT灌注成像在评价脑微循环方面的应用价值。方法选择12例颅脑损伤患者在术后6～20h内行常规CT和CT灌注成像检查。结果早期常规头颅CT平扫,除颅脑损伤征象和术后改变外,无缺血表现7例;脑实质低密度缺血灶5例,占41．67％。11例患者的灌注参数图像[局部脑血流量（rCBF）、局部脑血容量（rCBV）、平均通过时间（MTT）]都有明确的异常表现,占91．67％,1例无变化。结论灌注CT能够在重型颅脑损伤术后早期显示脑组织灌注部位、范围及缺血程度,确定脑梗死的存在及灌注情况,并可进行定量研究,对临床早期选择预防脑梗死治疗方案具有一定的指导价值。可以作为指导治疗的一个指标。但受到病人病情、扫描时间、影像技术人员技术水平的影响。