【作者】 梅国花；

【导师】 张晨美；

【作者基本信息】 浙江大学 ， 儿科学， 2007， 硕士

【摘要】 研究背景小儿重症肺炎好发于婴幼儿，因年龄越小，呼吸器官发育越不成熟，防御免疫能力越差，肺部越易感染，且感染后易致局部器官发生免疫反应，感染后病原菌及其产生的毒素引起机体释放炎性介质，产生一系列炎症瀑布反应，导致组织缺血缺氧，细胞损伤，进一步死亡，最后导致脏器功能衰竭。在危重病患者由于各种原因导致多个内脏血流灌注减少时，血流进行重新分布，胃肠道是血流减少发生最早的器官，易发生缺血缺氧，且在循环恢复后是最迟恢复的脏器，故能反映全身的脏器灌注情况。一旦胃肠道脏器粘膜急性受损，使其免疫屏障减弱，细菌移位，从而导致毒血症，脓毒血症，甚至再次发生全身炎症反应综合症（Systemic Inflammatory Response Syndrome，SIRS），进一步可引起多脏器功能不全综合症（Multiple Organ Dysfunction Syndrome，MODS）。如何早期发现重症肺炎患儿存在胃肠道缺氧缺血情况?临床上最常用的是胃粘膜pH值（Intramucosal pH，pHi）测定。用标准胃粘膜pH值可以排除全身酸碱平衡的影响，而胃粘膜PCO₂与动脉血PCO2差值（Pg-aCO₂）被认为也能准确反映胃粘膜灌注（内脏灌注）情况。传统的观点认为血乳酸也是评价组织灌注的一项重要指标，在本文中进行了血乳酸与胃粘膜pH值对比，来明确哪项指标能更好地反映组织灌注及氧合情况。由于目前国内未见有关小儿重症肺炎患者胃粘膜pH值的临床意义的相关文献报告。因此，我们进行了本课题研究。研究目的本课题采用空气张力计法测定PgCO₂、Pg-aCO₂及标准胃粘膜pH值等指标，评估小儿重症肺炎时的胃粘膜灌注情况，并且比较胃粘膜pH值（pHi）与动脉血乳酸（Lac）、血中血红蛋白氧半饱和时氧分压（P50）、动脉氧萃取压(PO_2（x）)、氧合指数（PaO₂／FiO₂）、胃粘膜PCO₂与动脉血PaCO₂差值（Pg-aCO₂）之间的相关性，通过相关性分析来了解哪项指标在反映组织灌注和氧合情况是最敏感，且对比治疗前后Lac、P50、Po_2（x）、PaO₂／FiO₂、Pg-aCO₂、pHi有无显著性差异。材料与方法1．研究对象：随机选择2006年11月～2007年3月浙江大学附属儿童医院PICU行机械通气治疗的重症肺炎患儿30例。其中男18例，女12例；年龄44d～21m，平均年龄6.58±5.22m；体重3.8～9.5kg，平均体重5.83±2.56kg；呼吸衰竭30例。2．研究方法：（1）机械通气模式：德国Drager公司Evita-4型号的呼吸机，采用PSV-SIMV模式。（2）镇静方式：采用芬太尼针3～8μg／kg·h和力月西针1～5μg／kg·h，静脉维持。（3）患儿入住后予禁食，并置入空气张力测定管，且与Datex-OhmedaS／5^TM监护仪连接进行PgCO₂动态监测。（4）实验指标：30例病人分别于机械通气前15分钟测定1次PgCO₂称T₁，机械通气后1h、3h、8h、13h、18h、24h各监测1次PgCO₂，前后共监测7次，分别获得T₁、T₂、T₃、T₄、T₅、T₆、T₇的PgCO₂数值，监测每一个T值的同时抽取动脉血标本送检血气分析。根据公式计算出Pg-aCO₂和标准pHi值，同时记录血气分析中的P50、Iac、PaO₂／FiO₂、PO_2（x）。实验数据处理用均数±标准差（（?）±SD）表示，pHi与Pg-aCO₂、P50、Lac、PaO₂／FiO₂、PO_2（x）之间相关性采用Pearson相关性分析。治疗前后各指标变化用t检验，P＜0.05表示有显著性差异，所有统计通过SPSS10.0统计软件在计算机上完成。结果1．重症肺炎患儿在机械通气治疗前后24小时Pg-aCO₂和标准pHi、P50、Lac、PaO₂／FiO₂、PO_2（x）的变化如下：（1）Pg-aCO₂随着机械通气的治疗逐步下降，T₁与T₅、T₆、T₇，T₂与T₆、T₇，T₃与T₇有显著性差异（P＜0.05），其余各时间点两两比较无显著性差异。（2）pHi随着机械通气的治疗逐渐上升，除T₄与T₅、T₅与T₆、T₆与T₇无显著性差异，其余各时间点两两比较有显著性差异（P＜0.05）。（3）P50随着机械通气治疗后逐渐下降，T₁与T₆、T₇有显著性差异（P＜0.05），其余各时间点两两比较无显著性差异。（4）Lac随着机械通气治疗后逐渐下降，除T₁与T₂、T₃与T₄、T₄与T₅、T₆、T₇，T₅与T₆、T₇，T₆与T₇比较无显著性差异，其余各时间点两两比较有显著性差异（P＜0.05）。（5）PO_2（x）随着机械通气治疗后逐渐上升，T₁与T₂、T₂与T₃、T₃与T₄、T₄与T₅、T₆，T₅与T₆、T₇，T₆与T₇比较无显著性差异，其余各时间点两两比较有显著性差异（P＜0.05）。（6）PaO₂／FiO₂随着机械通气治疗后逐渐上升，T₁与T₆，T₁与T₇比较有显著性差异（P＜0.05），余时间点两两比较均无显著性差异。2、24小时所测得的pHi与Pg-aCO₂、P50、Lac、PO_2（x）、PaO₂／FiO₂指标的相关性比较如下：（1）pHi与Pg-aCO₂呈负相关（P＜0.001）。（2）pHi与P50呈负相关（P＜0.001）。（3）pHi与Lac呈负相关（P＜0.001）。（4）pHi与PO_2（x）呈正相关（P＜0.01）。（5）pHi与PaO₂／FiO₂呈正相关（P＜0.05）。结论1、重症肺炎患儿存在胃粘膜缺氧缺血情况。2、胃粘膜pH值较其他组织氧合指标能更加准确、敏感地反映胃粘膜缺氧缺血及全身组织氧合情况。更多还原

【Abstract】 Research BackgroundSevere pneumonia is a common disease among infants. The younger the infant means the less maturity of his/her respiratory organ and the less immunity to the disease, which raised the possibility for pulmonary infection and immune reaction of local organs. Upon infection, the pathogenic bacteria and the endotoxin it generated will cause the organs to generate inflammatory mediators, which finally leading to organ function failure through a process of cascade effect in which ischemia and hypoxia, injury and death of cells are resulted. The severely infected pediatric patients will suffer a diminishing blood flow in internal organs due to various reasons which induced a redistribution of blood flow. The gastrointestinal organs are the first organs suffered from such a diminishing of blood flow and are inclined to face hypoxic-ischemic, and more importantly, they are also the last organs to recover in the whole recovery process of blood circulation, together make them the best indicators for blood flow conditions throughout the body. Once the gastrointestinal mucosa suffered acute organ damages, the weakening immune barrier and the translocation of intestinal bacteria will cause endotoxemia and sepsis or even cause Systemic Inflammatory Response Syndrome （SIRS） again, which may finally lead to Multiple Organ Dysfunction Syndrome （MODS）.The most commonly used clinical method for gastrointestinal hypoxic-ischemic detecting in pediatric patients with severe pneumonia in early stages is themeasurement of Gastric Intramucosal pH （pHi）. This method can exclude the influences exerted by acid base balance, while gastric-arterial PCO2 gap is considered to be an accurate indicator for intramucosal or splanchnic perfusion conditions. Traditionally, researchers also believe that Blood Lactate can serve as an effective indicator for tissue perfusion. Upon these considerations, this paper carried out a comparison between Blood lactate and gastric intramucosal pH, so as to identify which one better reflect the tissue perfusion and oxygenation conditions.Contemporarily there’s still no relative literature or research report about the clinical significance of the monitoring of gastric pH-value of pediatric patients with severe pneumonia, thus provided the necessity for this research.Research ObjectiveIn this research, we utilize air tonometry catheter to measure the indicators of intramucosal perfusion conditions, such as PgCO₂, Pg-aCO₂ and standard pHi. We will also make comparison about the correlations between pHi and arterial blood lactate, P50, PO_2（x）, PaO₂/FiO₂, gastric-arterial PCO₂ gap so as to provide insights about which indicator is most sensitive as far as the reflection of tissue perfusion and oxygenation conditions to be concerned, and if there exist significant differences in Lac、 P50、Po_2（x）、 PaO₂/FiO₂、Pg-aCO₂、 pHi before and after the surgical treatment.Material and Methods1. Research Objects: From November, 2006 to March, 2007, 30 pediatric patients with severe pneumonia which received mechanical ventilation treatment in Pediatric Intensive Care Unit（PICU） of Children’s Hospital Affiliated to Zhejiang University School of Medicine were chosen at random. Among the research objects there are 18 males and 12 females, age from 44 days to 21 months with an average age of 6.58±5.22 months, weigh 3.8 to 9.5kg with an average weight of 5.83 ± 2.56kg. Among them there are 8 patients with congenital heart disease （CHD）, and 30 patients with respiratory failure.2. Research Methods:1) Mechanical Ventilation Treatment Methods: Evita-4 ventilator machine made by Drager Corp.（Germany）, utilize PSV-SIMV mode.2 ) Sedation Methods: 3-8μg/kg.h Fentany Injection and 1-5 μg/kg.h Midazdam Injection, slow continuously transfusion by vein.3 ) Fasting and implementation of air tonometric catheters upon hospitaladmissions for pediatric patients, dynamic monitoring of PgCO₂ through a Datex-OhmedaS/5^TMmonitor.4 ) Experimental Indicators: PgCO₂ were measured 15 minutes before mechanical ventilation treatment （T₁） for all of 30 patients, measured again for 1h, 3h, 8h, 13h, 18h, 24h after mechanical ventilation treatment, labeled T₁, T₂, T₃, T₄, T₅, T₆, T7, respectively. Together with each value of T, arterial blood gas was determined at all of the above time points. The Pg-aCO₂ and standard pHi are calculated on the basis of formula, P50, lac, PaO₂/FiO₂ and PO_2（x） in the analysis will also be recorded.The data in the experiment will be expressed in the form of Mean ± Standard deviation （ X|- ± SD）.Pearson Correlate analysis will be employed to analyze correlation between pHi and Pg-aCO₂, P50, Lac, PaO₂/FiO₂, PO_2（x）. The change in indicators before and after mechanical ventilation treatment will be testified by t-test, in which significant difference are indicated if P<0.05. All the statistical analysis will be realized with SPSS 10.0.Research Results1. The change in Pg-aCO₂ and standard Phi, P50, Lac, PaO₂/FiO₂, PO_2（x） 24 hours before and after the mechanical ventilation treatment for the pediatric patients are as follows:1) Pg-aCO₂ was lowered gradually upon the treatment. There’s significant difference between T₁ and T₅, T₆, T₇; T₂ and T₆, T₇; T₃ and T₇ （P<0.05）. There’s no significant difference between each pair of the other time points.2) pHi was leveled up gradually upon the treatment. There’s significant difference between each pair of the time points, except for T₄ and T₅; T₅ and T₆; T₆ and T₇ （P<0.05）.3) P50 was lowered gradually upon the treatment. There’s significant difference between T₁ and T₆, T₇ （P<0.05）. There’s no significant difference between each pair of the other time points.4) Lac was lowered gradually upon the treatment. There’s significant difference between each pair of the time points, except for T₁ and T₂; T₃ and T₄; T₄ and T₅, T₆, T₇; T₅ and T₆, T₇; T₆ and T₇ （P<0.05）.5) PO_2（x） was leveled up gradually upon the treatment. There’s significant difference between each pair of the time points, except for T₁ and T₂; T₂ and T₃; T₃ and T₄; T₄ and T₅, T₆; T₅ and T₆, T₇; T₆ and T₇ （P<0.05）.6) PaO₂/FiO₂ was leveled up gradually upon the treatment. There’s significantdifference between T₁ and T₆; T₁ and T₇ （P<0.05）, There’s no significant difference between other each pair of the time points.2. Correlation between Phi and Pg-aCO₂, P50, Lac, PO_2（x）, PaO₂/FiO₂ during the 24 hours are as follows:1) There’s negative correlation between pHi and Pg-aCO₂ （P<0.001）.2) There’s negative correlation between pHi and P50 （P<0.001）.3) There’s negative correlation between pHi and Lac （P<0.001）.4) There’s positive correlation between pHi and PO_2（x） （P<0.01）.5) There’s positive correlation between pHi and PaO₂/FiO₂ （P<0.05）.Conclusion1. Hypoxic-ischemic existed among pediatric patients with severe pneumonia.2. Gastric Intramucosal pH（pHi） can serve as a better sensitive and accurateindicator for tissue perfusion and oxygenation conditions.更多还原