Cardiac function during hemorrhagic shock and crystalloid resuscitation

It is concluded that (1) myocardial failure develops during hypovolemic shock; (2) inadequate coronary perfusion contributes to the decrease in myocardial function; (3) inadequate resuscitation prolongs myocardial dysfunction and decreased coronary blood flow and may lead to terminal arrhythmias; (4) crystalloid resuscitation relieves heart failure and corrects myocardial ischemia; and (5) no evidence exists for cardiac overload with use of large volumes of crystalloid.     

Initial resuscitation of hemorrhagic shock

The primary treatment of hemorrhagic shock is control of the source of bleeding as soon as possible and fluid replacement. In controlled hemorrhagic shock (CHS) where the source of bleeding has been occluded fluid replacement is aimed toward normalization of hemodynamic parameters. In uncontrolled hemorrhagic shock (UCHS) in which bleeding has temporarily stopped because of hypotension, vasoconstriction, and clot formation, fluid treatment is aimed at restoration of radial pulse, or restoration of sensorium or obtaining a blood pressure of 80 mmHg by aliquots of 250 ml of lactated Ringer's solution (hypotensive resuscitation). When evacuation time is shorter than one hour (usually urban trauma) immediate evacuation to a surgical facility is indicated after airway and breathing (A, B) have been secured ("scoop and run"). Precious time is not wasted by introducing an intravenous line. When expected evacuation time exceeds one hour an intravenous line is introduced and fluid treatment started before evacuation.     

失血性休克后液体复苏的研究进展

背景 失血性休克是外伤死亡的主要原因.在重危病例的急救和围手术期的处理中,液体复苏起着关键性的治疗作用. 目的 就重度失血性休克后液体治疗方案的研究进展作一综述. 内容 除了传统的晶体液,近年来开发了诸多新品种的液体用于复苏,如丙酮酸钠溶液等.复苏方式的研究也在静脉复苏的基础上拓展到了腹腔复苏. 趋向 丙酮酸钠溶液以及腹腔复苏是近年来研究提出的新的复苏液体和复苏方案,通过已有的研究已经证实其积极的治疗作用.其应用于失血性休克的方法、时间、疗效等仍需更进一步研究.     

Controlled resuscitation for uncontrolled hemorrhagic shock

OBJECTIVE: To test the hypothesis that controlled resuscitation can lead to improved survival in otherwise fatal uncontrolled hemorrhage. METHODS: Uncontrolled hemorrhage was induced in 86 rats with a 25-gauge needle puncture to the infrarenal aorta. Resuscitation 5 minutes after injury was continued for 2 hours with lactated Ringer's solution (LR), 7.3% hypertonic saline in 6% hetastarch (HH), or no fluid (NF). Fluids infused at 2 mL x kg(-1) x min(-1) were turned on or off to maintain a mean arterial pressure (MAP) of 40, 80, or 100 mm Hg in six groups: NF, LR 40, LR 80, LR 100, HH 40, and HH 80. Blood loss was measured before and after 1 hour of resuscitation. RESULTS: Survival was improved with fluids. Preresuscitation blood loss was similar in all groups. NF rats did not survive 4 hours. After 72 hours, LR 80 rats (80%) and HH 40 rats (67%) showed improved survival over NF rats (0%) (p < 0.05). Rebleeding increased with MAP. Attempts to restore normal MAP (LR 100) led to increased blood loss and mortality. CONCLUSION: Controlled resuscitation leads to increased survival compared with no fluids or standard resuscitation. Fluid type affects results. Controlled fluid use should be considered when surgical care is not readily available.     

Brain tissue oxygenation during hemorrhagic shock, resuscitation, and alterations in ventilation

OBJECTIVES: Recently developed polarographic microelectrodes permit continuous, reliable monitoring of oxygen tension in brain tissue (PbrO2). The aim of this study was to investigate the feasibility and utility of directly monitoring PbrO2 in cerebral tissue during changes in oxygenation or ventilation and during hemorrhagic shock and resuscitation. We also sought to develop a model in which treatment protocols could be evaluated using PbrO2 as an end point. METHODS: Licox Clark-type polarographic probes were inserted in the brain tissue of 16 swine to monitor PbrO2. In eight swine, changes in PbrO2 were observed over a range of fractional concentrations of inspired O2 (FiO2) as well as during periods of hyperventilation and hypoventilation. In eight other swine, PbrO2 was monitored during a graded hemorrhage of up to 70% estimated blood volume and during the resuscitation period. RESULTS: When FiO2 was elevated to 100%, PbrO2 increased from a baseline of 15+/-2 mm Hg to 36+/-11 mm Hg. Hyperventilation while breathing 100% oxygen resulted in a 40% decrease in PbrO2 (p < 0.05), whereas hypoventilation increased PbrO2 to 88 mm Hg (p < 0.01). A graded hemorrhage to 50% estimated blood volume significantly reduced PbrO2, mean arterial pressure, and intracranial pressure (p < 0.01). Continued hemorrhage to 70% estimated blood volume resulted in a PbrO2 of 2.9+/-1.5 mm Hg. After resuscitation, PbrO2 was significantly elevated, reaching 65+/-13 mm Hg (p < 0.01), whereas mean arterial pressure and cerebral perfusion pressure simply returned to baseline. CONCLUSION: Directly measured PbrO2 was highly responsive to changes in FiO2, ventilatory rate, and blood volume in this experimental model. In particular, hypoventilation significantly increased PbrO2, whereas hyperventilation had the opposite effect. The postresuscitation increase in PbrO2 may reflect changes in both O2 delivery and O2 metabolism. These experiments set the stage for future investigations of a variety of resuscitation protocols in both normal and injured brain.     

Advances in fluid resuscitation of hemorrhagic shock.

The optimal fluid for resuscitation in hemorrhagic shock would combine the volume expansion and oxygen-carrying capacity of blood without the need for cross-matching or the risk of disease transmission. Although the ideal fluid has yet to be discovered, current options are discussed in this review, including crystalloids, colloids, blood and blood substitutes. The future role of blood substitutes is not yet defined, but the potential advantages in trauma or elective surgery may prove to be enormous.     

限制性液体复苏治疗失血性休克的临床研究

目的 探讨失血性休克早期限制性液体复苏的临床意义.方法 分析我院60例未控制失血性休克的液体复苏方法,比较常规液体组(n=30)与限制性液体复苏组(n=30)两种方法的治愈率、病死率及实验室指标血红蛋白(HBG)、红细胞压积(HCT)、血小板(PLT)、凝血酶原时间(PT)的结果.结果 常规组输液量(2 980±564)ml,治愈率66.7%、病死率33.3%,限制性组输液量(1980±302)ml,治愈率90.0%、病死率10.0%,两组间差异有统计学意义(P＜0.05),HBG、HCT、PLT、PT的比较,两组间差异有统计学意义(P＜0.01).结论 高渗液早期限制性液体复苏可提高治愈率,降低病死率,与常规复苏组比较不致于扰乱机体代偿机制及内环境.     

Hypertonic saline solution resuscitation in hemorrhagic shock dogs

Objective: To find out the optimal concentration,infusion rate and dosage of saline for resuscitation. Methods: Forty-five dogs were used to establish hypovolemic shock models. The dogs were resuscitated with saline of different concentrations and different dosages under different infusion rates, and the resuscitation results were compared. Results: The best concentration was 7.5%, the best rate of infusion 20 ml/min ( a volume equivalent to 15 % of the shed blood ) and the best dosage 5.71 ml/kg. The method was effective for resuscitation, the mean arterial pressure (MAP) could be elevated to 89 % of the baseline,and this MAP could be kept for more than one hour. Conclusions： Using 7.5% sodium chloride solution equivalent to 15% of the shed blood at an infusion rate of 20 ml/min can achieve a best resuscitation result.     

Delayed immune dysfunction following hemorrhagic shock and resuscitation

Immune system function is thought to be depressed after hemorrhagic shock. We evaluated the delayed effect of hemorrhagic shock on the immune system in rats with and without spleens and investigated the effect of the colloid hetastarch on reticuloendothelial system (RES) function. There were six groups: controls (N = 30, no shock), two groups of shocked animals resuscitated with either hetastarch (HES, N = 13) or lactated Ringer's (LR, N = 13); the remaining three groups were identical except that splenectomy had been performed (N = 16, N = 14, and N = 16, respectively). One week after shock and resuscitation, all groups were challenged with intravenous Streptococcus pneumoniae; quantitative blood and tissue (liver, lung, and spleen) cultures were then obtained. There were no differences between the HES and LR groups. In nonsplenectomized animals, colony counts in the blood, liver, lung, and spleen were significantly higher in shocked animals when compared with controls. Splenectomized rats had no significant differences between shocked groups and controls. These data demonstrate that delayed immune function is depressed in nonsplenectomized rats. Splenectomy causes more severe immune dysfunction than does shock. Also, in similar animals without splenectomy, hetastarch does not appear to alter delayed RES function.     

Starch-deferoxamine conjugate inhibits hepatocyte Ca2+ uptake during hemorrhagic shock and resuscitation

BACKGROUND: This study investigated whether hepatocyte Ca2+ dysregulation after hemorrhagic shock and resuscitation could be modulated by the iron chelator hydroxyethyl starch-conjugated deferoxamine (HES-DFO). METHODS: In a randomized experimental study, anesthetized rats (n = 7) were bled for 60 minutes to maintain mean arterial blood pressure at 40 mm Hg. They were then resuscitated with 60% of shed blood and threefold the shed-blood volume as lactated Ringer's solution, 1 mL of pentastarch solution (hydroxyethyl starch 10%) per mL of shed blood, or 1 mL of HES-DFO solution (10%) per mL of shed blood. In isolated hepatocytes, the rate of Ca2+ influx (Ca2+ in), total Ca2+ uptake (Ca2+ up), and membrane Ca2+ flux (Ca2+ flux) were determined by 45Ca incubation. Reduced or oxidized glutathione and malondialdehyde concentrations were assessed fluorometrically. RESULTS: Significant increases of hepatocellular Ca2+ in, Ca2+ up, and Ca2+ flux were observed in rats resuscitated with lactated Ringer's solution compared with control groups (p < 0.05). Although hydroxyethyl starch decreased Ca2+ in but not Ca2+ up, HES-DFO not only prevented the increase of Ca2+ in and Ca2+ up but also inhibited hepatocyte oxidative injury. CONCLUSION: Iron-catalyzed oxyradical production and membrane peroxidation seem to alter hepatocyte Ca2+ homeostasis after hemorrhagic shock and resuscitation.     

失血性休克复苏目标的认识

休克是一以组织灌注不足为特点的病理状态，该状态如未得到及时纠正，可引起广泛组织细胞缺氧代谢，触发机体全身炎症反应，导致严重组织细胞损伤，最终发生多器官功能障碍综合征（MODS），甚至多器官衰竭（MOF）。引起休克的原因多种多样．但按其病理生理学特点，休克可分为以下4类：①低血容量性休克；②心源性休克；③梗阻性休克；④分布性休克。失血性休克是低血容量性休克的经典代表，是在创伤及其他意外事件中较短时间内大量血液丢失，导致循环前负荷急剧下降，并且超出机体本身的代偿能力而出现的循环功能障碍。     

失血性休克液体复苏实验研究进展

失血性休克的液体复苏研究虽为时较长,但至今对其研究仍非常活跃,其研究结果对临床治疗有积极的参考意义。现就近几年来关于不同复苏液对机体影响的研究、常用复苏液的种类及一些复苏方法作一介绍。     

低压复苏对非控制性出血性休克的作用

目前国内外的动物实验和部分临床研究结果显示，低压复苏是治疗非控制性出血性休克较为合理的方案，但还没有人从增加血容量，减少应激反应引起的血管收缩、改善组织微循环氧供方面进行研究。本研究拟观察低压及低压扩容复苏对腹腔实质脏器损伤非控制性出血性休克的治疗效果。