肝缺血再灌注后肺损伤机制及乌司他丁保护作用的实验研究

目的 研究肝缺血再灌注后肺损伤的机制以及乌司他丁的保护作用.方法 新西兰白兔24只,随机分为3组,每组8只.假手术组：麻醉后分离肝门,游离肝动静脉,关腹,120 min后处死.缺血再灌注组：夹闭左侧叶、左中央叶、右中央叶的血管,缺血60 min后再灌注60 min后立即处死.乌司它丁组同缺血再灌注组制作部分肝缺血再灌注模型,但于阻断前15 min注射乌司它丁2万U/kg.测定阻断前（T0）、阻断50min（T1）、再灌注10min（T2）、再灌注60min（T3）四个时点动脉血压、动脉血血气分析和TNF-α、IL-8水平.肝肺病理切片光镜观察、肺干湿重比、肺灌洗液蛋白含量及磷脂水平、肺组织丙二醛（MDA）含量、超氧化物歧化酶（SOD）活力、髓过氧化物酶（MPO）活力、肺组织SP-A mRNA及SP-A蛋白表达水平.结果 病理结果显示,乌司它丁组缺血再灌注肺损害较轻.缺血再灌注组和乌司它丁组pH阻断后降低,TNF-α和IL-8升高,TNF-α、IL-8水平、干湿重比、MDA、MPO高于假手术组,灌洗液蛋白浓度、PC、PG含量、SOD、SP-A蛋白表达低于假手术组（P＜0.05）,而乌司它丁组各项结果要好于缺血再灌注组（P＜0.05）.结论 肝缺血再灌注会导致肺损伤,缺血前给予乌司它丁可以减轻肺损伤.     

门静脉淤血对肝脏缺血再灌注后肺脏和肾脏损伤的影响

目的 探讨门静脉淤血对肝脏缺血再灌注后肺脏和肾脏损伤的影响及机制.方法 对24只新西兰大白兔行肝门阻断,同时经门静脉肝脏原位冷灌注30 min,恢复灌流时按门静脉淤血去除量的不同随机分为3组:A5组去除5 ml、A10组去除10 ml、B组不去除门静脉淤血,每组8只.另取8只作为对照(C组),仅行手术解剖,不做肝门阻断及肝脏灌注.检测去除门静脉淤血对恢复灌流4 h后血清内毒素、肿瘤坏死因子-α(TNF-α)、尿素氮(BUN)、肌酐(Cr)的影响;取肺脏、肾脏组织观察组织学改变并检测组织匀浆丙二醛(MDA)、超氧化物歧化酶(SOD)及肺湿/干重、肺灌洗液蛋白含量的变化.结果 去除门静脉淤血能降低复流后血清内毒素、TNF-α、BUN、Cr、肺湿/干重、肺灌洗液蛋白含量和肺脏、肾脏组织匀浆中MDA含量.其中A5组血清TNF-α、Cr、肺灌洗液蛋白含量、肾组织匀浆中MDA均明显低于B组(P＜0.05);A10组血清内毒素、TNF-α肺湿/干重及肺组织匀浆中MDA也明显低于B组(P＜0.05).去除门静脉淤血可增加肺脏、肾脏组织匀浆中SOD活性,其中A5组肾组织匀浆中SOD活性明显高于B组(P＜0.05).同时,去除门静脉淤血能明显改善肺脏、肾脏组织学变化.结论 去除门静脉淤血可以减轻肝脏缺血再灌注后肺脏、肾脏功能的损伤,其机制可能与门静脉淤血去除减少内毒素吸收,进而降低了血清TNF-α产生有关.     

淤血预处理减轻兔肝门静脉阻断模型中肠道淤血-再灌注损伤

目的 观察淤血预处理对兔肝门静脉阻断模型中肠道淤血-再灌注引起的肠道损伤和肝脏损伤的影响。
方法 选取雄性日本大耳兔75只,体重2.5～5.0 kg,随机分为五组：假手术组（S组）、淤血-再灌注组（OC组）、预处理A组（OC5组）、预处理B组（OC10组）、预处理C组（OC15组）,每组15只。S组仅行剖腹手术暴露第一肝门30 min,OC组进行门静脉阻断30 min后开放门静脉。三个预处理组门静脉操作分别为OC5组夹闭5 min,开放5 min;OC10组夹闭10 min,开放10 min;OC15组夹闭15 min,开放15 min,随后阻断门静脉30 min后开放。术后2、8、24 h通过门静脉取血,检测血清中丙二醛（MDA）含量和内毒素、肿瘤坏死因子-α（TNF-α）、丙氨酸转氨酶（ALT）浓度。术后24 h血液样本采集完毕后,再次麻醉并处死以获取回肠末端肠黏膜及肝组织,显微镜下观察病理形态学结构改变。
结果 与S组比较,术后2、8、24 h OC组、OC5组、OC10组和OC15组血清MDA含量、内毒素、TNF-α、ALT浓度明显升高（P＜0.05）。与OC组比较,术后2、8、24 h OC5组、OC10组和OC15组血清MDA含量、内毒素、TNF-α、ALT浓度明显降低（P＜0.05）。与OC5组比较,术后2、8、24 h OC10组血清MDA含量、TNF-α、ALT浓度明显降低（P＜0.05）。与OC5组比较,术后2、8 h OC10组血清内毒素浓度明显降低（P＜0.05）。与OC10组比较,术后8 h OC15组血清MDA含量、ALT浓度明显升高（P＜0.05）。与S组比较,OC组、OC5组、OC10组和OC15组肠黏膜损伤Chiu评分明显升高（P＜0.05）。与OC组比较,OC5组、OC10组和OC15组黏膜损伤Chiu评分明显降低（P＜0.05）。与OC5组比较,OC10组、OC15组的肠黏膜损伤Chiu评分明显降低（P＜0.05）。
结论 淤血预处理可以减轻由于肝门静脉阻断导致的肠道淤血-再灌注损伤,减轻内毒素血症、过度炎性反应及氧自由基对肝脏的损伤。     

谷氨酰胺对大鼠肝门阻断后肝脏Bcl-2 mRNA表达的影响及其保护作用

目的：探讨谷氨酰胺（L—glutamine，GIn）对肝门阻断后肝脏细胞凋亡及Bcl-2mRNA表达的影响。方法：雄性Wistar大鼠，随机分为假手术组（A组）、对照组（B组）和实验组（C组）3组。采用Pringle’s法进行肝门阳断，持续35min，肝门阻断前C组大鼠腹腔注射Gin。分别于肝门阻断前及再灌注后2,4和24h，每组各选取10只大鼠，测定血清ALT、AST、乳酸脱氢酶（lactic dehydrogenase，LDH）含量；检测肝组织谷胱甘肽（glutathione，GSH）、丙二醛（malondialdehyde，MDA）的含量；采用原位末端脱氧核苷酸转移酶法（terminal deoxynucleotidy ltransferase—mediated DUTP nick end labeling method，TUNEL）检测肝脏细胞凋亡，并计算凋亡指数（apoptosic index，AD；采用RT—PCR方法检测肝Bcl-2mRNA的表达。结果：与B组相比，再灌注后C组肝组织中MDA含量下降（P〈0．05），而GSH水平增高（P〈0．05）；血清ALT、AST、LDH含量及Al均明显刚氏（P〈0．05）；Bcl-2mRNA表达则显著增强（P〈0．05）。结论：Gin能够减轻过刘匕损伤，上调肝脏Bcl-2 mRNA的表达，抑8UST细胞凋亡，从而在肝门阻断中发挥保护作用。     

去除门静脉淤血减轻肝脏缺血再灌注损伤的实验研究

目的 探讨去除门静脉淤血对肝脏缺血再灌注损伤的影响及机制.方法 检测家兔肝脏原位冷灌注20、30、40 min后淤血的门静脉中内毒素含量变化,观察门静脉淤血去除对恢复灌流后4 h血清内毒素、丙氨酸转氨酶(ALT)、透明质酸(HA)、肝组织匀浆丙二醛(MDA)、超氧化物歧化酶(SOD)及肝组织核因子-κB(NF-κB)活性的影响.结果 门静脉淤血中内毒素含量随阻断时间延长明显升高(P＜0.01),同一阻断时间每去除2.5 ml淤血血清内毒素含量显著下降(P＜0.01).在阻断30 min和40 min组,去除门静脉淤血能降低血清ALT、HA、及肝组织匀浆MDA的含量和肝组织NF-κB活性,增加肝组织匀浆SOD活性,与不去除相比较差异有统计学意义(P＜0.05).在阻断20 min组去除门静脉淤血与不去除相比较,各检测指标差异无统计学意义(P＞0.05).结论 门静脉淤血中内毒素含量随阻断时间延长明显升高,可能是引起肝脏损伤的主要原因;去除门静脉淤血可以减轻肝脏的再灌注损伤,其机制可能与门静脉淤血去除减少内毒素吸收,进而降低肝组织NF-κB活化有关.     

丙泊酚对大鼠脑缺血-再灌注损伤后海马线粒体ATP含量和ATP酶活性的影响

目的观察丙泊酚对大鼠脑缺血-再灌注损伤后海马线粒体三磷酸腺苷（ATP）含量、ATP酶活性、脂质过氧化和超微结构的影响.方法采用大鼠全脑缺血-再灌注损伤模型.40只Wistar大鼠随机分为假手术组（A组）、缺血-再灌注对照组（B组）和缺血-再灌注丙泊酚预处理组,后者按丙泊酚用量又分为50 mg/kg（C1组）、100 mg/kg（C2组）和150 mg/kg（C3组）三个亚组.观察全脑缺血10 min再灌注60 min时海马线粒体的超微结构、ATP和丙二醛（MDA）的含量及Na^＋-K^＋-ATP酶、Ca^2＋-ATP酶、超氧化物歧化酶（SOD）和谷光甘肽（GSH）活性的变化.结果与B组比较,丙泊酚各处理组海马线粒体的ATP含量、Na^＋-K^＋-ATP酶、Ca^2＋-ATP酶、SOD和GSH的活性均有不同程度的增高（P〈0.05或0.01）,MDA含量有不同程度的降低（P〈0.05或0.01）,线粒体超微结构的损伤程度亦明显减轻.结论丙泊酚对脑缺血-再灌注损伤的保护效应可能与其抑制线粒体脂质过氧化反应,减轻线粒体的损伤,促进线粒体ATP含量和ATP酶活性的恢复有关.     

RNA干扰Kupffer细胞肿瘤坏死因子-α减轻大鼠肝脏缺血再灌注损伤

目的 观察RNA干扰肝脏Kupffer细胞肿瘤坏死因子-α(TNF-α)对大鼠肝脏缺血再灌注损伤的保护作用.方法 构建针对大鼠TNF-α基因的短发夹状RNA(shRNA)真核表达载体.肝脏缺血再灌注损伤前48 h经门静脉注射磷酸盐缓冲液(PBS)、空载体或TNF-α shRNA.实验随机分为4组,假手术组、PBS组、空载体组和shRNA组.阻断大鼠70%入肝血流40 min,再灌注6 h检测血清谷丙转氨酶(ALT)、谷草转氨酶(AST)、肝脏Kupffer细胞TNF-α mRNA、血清TNF-α、肝组织中丙二醛(MDA)以及超氧化物岐化酶(SOD)含量.结果 与PBS组和空载体组比较,shRNA组再灌注6 h后血清ALT和AST水平显著降低(P＜0.05),Kupffer细胞TNF-α mRNA水平、血清TNF-α水平(56.6±6.7 pg/ml比87.8±8.7 pg/ml和96.5±7.3 pg/ml,P＜0.05)、肝组织中MDA含量(93.4±13.3 nmol/mg比133.5±12.4 nmo1/mg和136.7±13.6 nmol/mg,P＜0.05)显著降低,SOD活性显著升高(22.4±4.6 U/mg比12.2±3.1 U/mg和11.4±2.9 U/mg,P＜0.05).结论 RNA干扰Kupffer细胞TNF-α基因的表达可以减轻大鼠肝脏缺血再灌注损伤.     

氨溴索对大鼠肝脏缺血再灌注损伤的保护作用

目的：探讨氨溴索对大鼠肝脏缺血再灌注损伤（I/RI）的保护作用及其机制。方法：18只雄性Wistar大鼠被随机均分为假手术组、肝I/RI模型组（模型组）、氨溴索预处理+肝I/RI模型组（氨溴索预处理组）。肝I/RI模型采用阻断入肝血流30 min后再灌注方法诱导,氨溴索预处理组于缺血前20 min尾静脉注射氨溴索（100 mg/kg）,而模型组给予等体积生理盐水。术后6 h处死大鼠,检测血清丙氨酸转氨酶（ALT）和天冬氨酸转氨酶（AST）水平和肝组织病理学改变,同时检测肝组织超氧化物岐化酶（SOD）,谷胱甘肽（GSH）,丙二醛（MDA）含量,caspase-3的活化水平。结果：与假手术组比较,模型组与氨溴索预处理组血清ALT和AST水平明显升高（均P<0.05）;肝组织出现明显的病理学改变;肝组织SOD和GSH含量明显下降,而MDA水平明显升高（均P<0.05）;肝组织caspase-3活化水平明显升高（均P<0.05）。与模型组比较,氨溴索预处理组以上各项指标的变化均明显减弱（均P<0.05）。结论：氨溴索预处理能减轻大鼠肝脏I/RI,机制可能与其调控抗氧化和抗凋亡信号通路有关。     

肠道缺血再灌注损伤时肠淋巴干结扎对系统炎性反应的影响

目的比较大鼠肠道缺血再灌注损伤时肠淋巴干结扎与不结扎对循环中炎性介质和细菌内毒素的影响。方法采用肠道缺血再灌注模型进行肠系膜淋巴管结扎。大鼠随机分4组，每组10只：空白组（A组）；假手术组（B组）；肠道缺血再灌注组（C组）；肠道缺血再灌注加淋巴干结扎组（D组）。缺血再灌注后，作肠系膜淋巴结培养计算细菌易位率；检测循环中内毒素、D-乳酸、二胺氧化酶、TNF—α、IL-1β、IL-6和sICAM-1水平。结果细菌易位率A、B两组为0；C组40％，D组20％。与A、B组比较，C、D两组内毒素、D-乳酸和二胺氧化酶水平显著增高（P〈0．05），且D组显著低于C组；血循环中各细胞因子除sICAM-1在D组与C组之间没有显著差异外，C组的IL-1β、IL-6和TNF-α浓度均明显高于D组（P〈0．05）。结论肠道缺血再灌注损伤时，肠淋巴干结扎可减少细菌在肠系膜淋巴结的定植，并减轻肠道缺血再灌注的损伤及增加通透性，从而减轻全身炎性反应。     

选择性肝门阻断联合逆行肝切除治疗巨大肝癌对健侧肝组织的保护作用

目的：探讨选择性肝门阻断联合逆行肝切除治疗巨大肝癌对健侧肝组织再灌注损伤、余肝功能的影响。 方法：45例巨大肝癌（直径≥10 cm）患者按照Zelen设计的临床分组方案分为对照组和观察组,对照组行完全阻断第一肝门的顺行肝癌切除,观察组行选择性阻断第一肝门的逆行肝癌切除,两组均于肿瘤切除后留取少许健侧肝组织。检测两组患者术后1周总胆红素（TBIL）、谷丙转氨酶（ALT）、前白蛋白（PA）水平及健侧肝组织肝细胞凋亡情况、细胞内钙离子浓度（[Ca2+]i）、丙二醛（MDA）含量、超氧化歧化酶（SOD）活性。 结果：与对照组比较,观察组术后1周的ALT明显降低、PA含量明显升高（均P<0.05）,而TBIL水平差异无统计学意义（P>0.05）;健侧肝组织肝细胞凋亡水平、[Ca2+]i、MDA含量均明显下降,SOD活性明显增高（P<0.05）。 结论：与传统方法比较,选择性第一肝门阻断逆行肝切除术治疗巨大肝癌更有利于减少健侧肝组织的再灌注损伤和保护余肝功能。

     

Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background : We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI₂) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods : In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGFlα (stabile metabolite of PGI₂), TXB₂ (stabile metabolite of thromboxane A₂) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results : Following MT, arterial hypotension occurred along with a substantial PGI₂ release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF_1α (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same point in time plasma concentrations of TXB² (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41 ± (18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P = 0.001) were significantly higher in placebo-treated patients. Conclusion : Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI₂ release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A₂, presumably contributing to hemodynamic stability within 30 min after MT.     

A comparison of the inhibitory effects of four volatile anaesthetics on the metabolism of chlorzoxazone, a substrate for CYP2E1, in rabbits

Background: Halothane inhibits in vitro and in vivo activity of cytochrome P-450 (CYP) 2E1. There are several fluorinated volatile anaesthetics besides halothane, and most of them are defluorinated by CYP2E1. It is unclear whether other fluorinated anaesthetics inhibit the in vivo activity of CYP2E1.
Methods: We compared the inhibitory effects of therapeutic concentrations of four inhalational anaesthetics, halothane, enflurane, isoflurane, and sevoflurane, on chlorzoxazone metabolism in rabbits receiving artificial ventilation.
Results: All four inhalational anaesthetics decreased arterial blood pressure and increased plasma chlorzoxazone concentration. However, no significant differences in the plasma chlorzoxazone concentration were found between the four anaesthetics. The estimated chlorzoxazone clearance increased after beginning inhalation with all four agents, but no significant difference in clearance was noted between agents.
Conclusions: At therapeutic concentrations, the in vivo inhibitory effect on chlorzoxazone metabolism was similar for all four inhalational anaesthetics examined, even though their chemical characteristics and extent of hepatic metabolism differ considerably.     

Microspheres Based Detoxification System: A New Method in Convective Blood Purification

Abstract: A variety of protein-bound or hydrophobic substances, accumulating as a result of pathologic conditions such as exogenous or endogenous intoxications, are removed poorly by conventional detoxification methods because of low accessibility (hemodialysis), insufficient adsorption capabilities (hemosorption), low efficiency (peritoneal dialysis), or economic limitations (high-volume plasmapheresis). Combining advantages of existing methods with microspheric technology, a module-based system was designed. Major operating parameters of the latter can be modified to allow for adjustment to individual clinical situations. An extracorporeal blood circuit including a plasmafilter is combined with a secondary high-velocity plasma circuit driven by a centrifugal pump. Different microspheric adsorbers can be combined in one circuit or applied in sequence. Thus, a prolonged treatment can be tailored using specially designed selective adsorber materials. Comparing this system with existing methods (high-flux hemodialysis, molecular adsorbent recycling system), results from our in vitro studies and animal experiments demonstrate the superior efficiency of substance removal.     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

Bariatric Surgery in Some "Central and East-European (former Eastern bloc)"Countries - Current Status and Prediction for the Next Millennium

Background: Obesity is increasing globallly, including in the formerly "Eastern Bloc" countries. Methods: A survey was made of obesity and bariatric surgery. Results: In the 8 East and Central European countries studied, with total population 300 million, roughly 43% of the population was overweight (BMI 25-30), 23% obese (BMI > 30), with about 15 million people morbidly obese (BMI > 40). From 0-10 morbidly obese individuals/100,000/year undergo bariatric surgery. Conclusion: Most countries were found to provide inadequate treatment for obesity.The majority of the morbidly obese are not treated effectively. However, health-care awareness of obesity and bariatric surgeons are slowly increasing.     

Dilemma of Membrane Biocompatibility and Reuse

Abstract: Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation. leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.     

Influence of dopexamine hydrochloride on haemodynamics and regulators of circulation in patients undergoing major abdominal surgery

Background: Catecholaminergic support is often used to improve haemodynamics in patients undergoing major abdominal surgery. Dopexamine is a synthetic vasoactive catecholamine with beneficial microcirculatory properties. Methods: The influence of perioperative administration of dopexamine on cardiorespiratory data and important regulators of macro- and microcirculation were studied in 30 patients undergoing Whipple pancreaticduodenectomy. The patients received randomized and blinded either 2 μg · kg^?1 · min^?1 of dopexamine (n=15) or placebo (n=15, control group). The infusion was started after induction of anaesthesia and continued until the morning of the first postoperative day. Endothelin-1 (ET-1), vasopressin, atrial natriuretic peptide (ANP), and catecholamine plasma levels were measured from arterial blood samples. Measurements were carried out after induction of anaesthesia, 2 h after onset of surgery, at the end of surgery, 2 h after surgery, and on the morning of the first postoperative day. Results: Cardiac index (CI) increased significantly in the dopexamine group (from 2.61±0.41 to 4.57±0.78 1 · min^?1 · m^?2) and remained elevated until the morning of the first postoperative day. Oxygen delivery index (DO₂I) and oxygen consumption index (VO₂I) were also significantly increased in the dopexamine group (DO₂I: from 416±91 to 717±110 ml/m² · m²; VO₂I: from 98±25 to 157±22 ml/m² · m²), being significantly higher than in the control group. pHi remained stable only in the dopexamine patients, indicating adequate splanchnic perfusion. Vasopressive regulators of circulation increased significantly only in the untreated control patients (vasopressin: from 4.37±1.1 to 35.9±12.1 pg/ml; ET-1: from 2.88±0.91 to 6.91±1.20 pg/ml). Conclusion: Patients undergoing major abdominal surgery may profit from prophylactic perioperative administration of dopexamine hydrochloride in the form of improved haemodynamics and oxygenation as well as beneficial influence on important regulators of organ blood flow.     

Synergistic interaction between the effects of propofol and midazolam with fentanyl on phrenic nerve activity in rabbits

Background: It has been shown that the depressive effects of both propofol and midazolam on consciousness are synergistic with opioids, but the nature of their interactions on other physiological systems, e. g. respiration, has not been fully investigated. The present study examined the effect of propofol and midazolam alone and in combination with fentanyl on phrenic nerve activity (PNA) and whether such interactions are additive or synergistic. Methods: PNA was recorded in 27 anaesthetised and artificially ventilated rabbits. In three groups, propofol, fentanyl and midazolam were administered intravenously in incremental doses to construct dose-response curves for the depressant effects of each one on PNA. In another two groups, the effect of pretreatment with either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. on the effects of propofol and fentanyl respectively on PNA were studied. Results: Propofol and fentanyl caused a dose-dependent depression of PNA with complete abolition at the highest total doses of 16 mg · kg^?1 i. v. and 32 μg · kg^?1 i. v., respectively. In contrast, midazolam in incremental doses to a total of 0.8 mg · kg^?1 reduced mean PNA by 63%, but approximately 12% of PNA remained at a total dose as high as 6.4 mg · kg^?1. The mean ED₅₀s, calculated from dose-response curves, were 5.4 mg · kg^?1, 3.9 μg · kg^?1 and 0.4 mg · kg^?1 for propofol, fentanyl and midazolam, respectively. Initial doses of either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. acted synergistically with subsequent doses of either propofol or fentanyl to abolish PNA at total doses of 8 mg · kg^?1 and 8 μg · kg^?1, respectively. Conclusion: Fentanyl has a synergistic interaction with both propofol and midazolam on PNA and hence potentially on respiration.     

The analgesic effect of racemic ketamine in patients with chronic ischemic pain due to lower extremity arteriosclerosis obliterans

Background : Ketamine in sub-dissociative doses has been shown to have analgesic and phantom-Limb pain, where conventional treatment has often failed. Chronic ischemic pain due to lower extremity arteriosclerosis obliterans often responds poorly to analgesics, and the pain-generating mechanisms are not well understood.
Methods : Eight patients with rest pain in the lower extremity due to arteriosclerosis obliterans were given sub-dissociative doses of 0.15, 0.30, or 0.45 mg/kg racemic ketamine and morphine 10 mg as a 5-min infusion on four separate days in a cross-over, double-blind, randomised protocol. Plasma levels of (S)- and (R)-ketamine and their nor-metabolites were analysed with an enantioselective high-performance liquid chromatography (HPLC) method. Pain levels were evaluated with a visual analogue scale (VAS).
Results : Individual pain levels were highly variable during and after all the infusions but the pooled pain levels showed a dose-dependent analgesic effect of ketamine with a transient but complete pain relief in all patients at the highest dose (0.45 mg/ kg). Side-effects, mainly disturbed cognition and perception, were pronounced and dose-dependent. Morphine 10 mg had an analgesic peak at 20 min and 5/8 patients had complete pain relief. The remaining 3 patients also had high baseline pain scores, indicating a higher analgesic potency for the 0.30 and 0.45 mg/ kg ketamine doses than for morphine 10 mg.
Conclusion : We have demonstrated a potent dose-dependent analgesic effect of racemic ketamine in clinical ischemic pain. Due to a narrow therapeutic window, this analgesic effect is probably best utilised in combination with other analgesics.