下肢缺血预处理对未成熟心肌的保护作用

目的探讨下肢缺血预处理(LIP)对未成熟心肌保护作用的机制。方法采用下肢缺血预处理动物Langendorff离体心脏灌注模型,将30只日本长耳大白兔采用随机数字表法分为5组:缺血-再灌注损伤(I/R)组(n=6),建立灌注模型,灌注KH液15min转为工作心15min,全心停灌45min,恢复灌注15min改为工作心30min;E1组(n=6),动物麻醉后反复3次阻断双下肢血流5min,松开5min,建立模型,灌注15min转为工作心15min,全心停灌45min,恢复灌注15min改为工作心30min;E2组(n=6),双下肢缺血预处理前静脉注射超氧化物歧化酶至双下肢缺血预处理完毕,重复E1组方法;E3组(n=6),静脉注射蛋白激酶C(PKC)阻滞剂polymyxin(PMB),时间10min,重复E1组方法;E4组(n=6),静脉注射三磷酸腺苷(ATP)敏感性钾通道(mitoKATP)阻滞剂5-HD,时间10min,重复E1组方法。观察左心室功能恢复、心肌含水量(MWC)、血清肌酸激酶(CK)和乳酸脱氢酶(LDH)漏出率、心肌组织ATP和丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性、超氧阴离子自由基(O2.-)等指标。结果E1组的左心室功能恢复优于I/R组、E2组、E3组、E4组(P0.05),ATP含量、SOD活性均优于其它各组(P0.05),心肌含水量低于其它各组(P0.05),MDA含量、CK、LDH漏出率低于其它各组(P0.05);I/R组、E2组、E3组、E4组的以上指标比较均差异无统计学意义(P0.05)。预处理前、后E1组、E3组、E4组的O2.-差异有统计学意义(P0.05)。结论下肢缺血预处理对未成熟心肌具有明显的保护作用,其机制是通过PKC通路和mitoKATP通道起作用。     

热休克蛋白70表达对未成熟心肌和心肌间质的保护作用

目的 观察热休克蛋白70(HSP70)对未成熟心肌和心肌间质的保护作用.方法 健康新生长耳大白兔30只随机分为5组.对照组:腹腔注射生理盐水0.4 ml 24 h后取离体心脏,建立Langendorff离体心脏灌注模型;E4h、E12h、E24h、E48h组,腹腔注射去甲肾上腺素,4、12、24、48 h后分别取离体心脏,方法同对照组.测定心肌细胞中HSPT0含量、血流动力学指标、心肌含水量(MWC)、心肌肌酸激酶(CK)和乳酸脱氢酶(LDH)漏出率、三磷酸腺苷(ATP)含量、超氧化物歧化酶(SOD)和丙二醛(MDA)含量、心肌组织羟脯氨酸(HP)含量、内皮素(ET)含量、心肌细胞内Ca2+含量、心肌线粒体Ca2+-ATPase活性及其Ca2+含量、心肌线粒体合成ATP能力[ATP]m,心肌超微结构.结果 E24h组与其他各组比较,HSPT0含量明显增高(P＜0.01),MWC(72.48±1.36)低于其他各组(P＜0.05),ATP含量(11.64±1.87)、SOD活性(235.83±12.30)、心肌线粒体Ca2+-AT-Pase活性(18.46±1.95)、[ATP]m(106.26±9.42),HP含量(6.45±1.53)优于其他各组(P＜0.01),MDA含量(1.17±0.12)、CK(57.38±4.75),LDH漏出率(37.28±3.26)、心肌细胞内Ca2+含量(2.54±0.34)、心肌线粒体Ca2+含量(38.37±3.61)、ET含量(76.84±10.37)低于其他各组(P＜0.01),心肌超微结构损伤较其他各组明显减轻.结论 腹腔注射去甲肾上腺素24 h后可诱导未成熟心肌HSP70高表达,一定量的HSP70表达可明显减轻未成熟心肌和心肌间质的缺血再灌注损伤.     

蛋白激酶C和线粒体ATP敏感性钾通道在未成熟心肌预处理中的作用

目的探讨蛋白激酶C(PKC)和线粒体三磷酸腺苷敏感性钾通道(mitoKATP)在未成熟心肌预处理保护中的作用。方法采用Langendorff离体心脏灌注模型,30只新生日本长耳大白兔分为5组:缺血/再灌注组(I/R组),心脏缺血预处理组(E1组),蛋白激酶C(PKC)阻滞剂chelerythrine(CLT) 心脏缺血预处理(E2组),mitoKATP阻滞剂5-hydroxydecanoate(5-HD) 心脏缺血预处理(E3组),mitoKATP通道开放剂Diazoxide(Diaz)预处理组(E4组)。以血流动力学、生化指标、心肌超微结构等作为观察指标。结果E1和E4组心功能恢复、心肌含水量优于I/R、E2和E4组(P<0.05),三磷酸腺苷含量、超氧化物歧化酶活性、心肌线粒体Ca2 -ATPase活性、心肌线粒体合成三磷酸腺苷(ATP)的能力优于I/R、E2和E4组(P<0.01),丙二醛含量、血清肌酸激酶和乳酸脱氢酶漏出率、心肌细胞内Ca2 含量、心肌线粒体Ca2 含量低于I/R、E2和E4组(P< 0.01),心肌超微结构损伤较I/R、E2和E4组明显减轻。结论心肌缺血预处理对未成熟心肌具有明显的保护作用,其机制可能是通过PKC的激活和mitoKATP通道的开放起作用。     

非心脏缺血预处理对兔未成熟心肌的保护作用

目的　研究非心脏缺血预处理 ( IP)对未成熟心肌的保护作用 ,探讨未成熟心肌的保护方法。　方法　采用心脏缺血预处理 ( MIP)、双下肢缺血预处理 ( DL IP)和肾缺血预处理 ( RIP)兔 L angendorff灌注模型 ,比较 3种方法对缺血 -再灌注 ( IR)未成熟心肌损伤的效应。将 2 4只兔分为 4组 ,IR组 ,MIP组 ,DL IP组和 RIP组 ,每组 6只。测定左心室功能恢复、心肌含水量 ( MWC)、乳酸脱氢酶 ( L DH)漏出量、血清肌酸激酶 ( CK)漏出量、心肌三磷酸腺苷 ( ATP)、丙二醛( MDA)含量和超氧化物歧化酶 ( SOD)活性等指标。　结果　 MIP组、DL IP组和 RIP组左心室功能恢复指标、ATP含量和 SOD活性优于 IR组 ( P<0 .0 5 ) ,MWC低于 IR组 ( P<0 .0 5 ) ,L DH、CK漏出率和 MDA含量均低于 IR组 ( P<0 .0 1)。　结论　非心脏 IP对未成熟心肌具有明显的保护作用 ,与 MIP相同 ,可诱发同等效应的心肌保护作用。     

线粒体三磷酸腺苷敏感性钾通道在未成熟心肌缺血预处理中的作用

目的探讨线粒体三磷酸腺苷敏感性钾通道（mitoKATP）在未成熟心肌预处理保护中的作用,为未成熟心肌的保护提供依据。方法采用Langendorff离体心脏灌注模型,将24只新生（出生14～21d）日本长耳大白兔按随机数字表法分为4组：缺血／再灌注组（I／R组）,心脏缺血预处理组（E1组）,mitoKATP阻滞剂5-hydroxydecanoate（5-HD）＋心脏缺血预处理（E2组）,mitoKATP通道开放剂Diazoxide（Diaz）预处理组（E3组）;检测心脏功能恢复率、心肌含水量、血清肌酸激酶和乳酸脱氢酶漏出率、三磷酸腺苷（ATP）含量、超氧化物歧化酶活性、丙二醛含量、心肌细胞内Ca^2＋含量、心肌线粒体Ca^2＋含量、心肌线粒体Ca^2＋-三磷酸腺苷酶活性（Ca^2＋-ATPase）、心肌线粒体合成ATP的能力;电子显微镜观察心肌超微结构。结果E1组、E3组心功能恢复优于I／R组和E2组,心肌含水量低于I／R组和E2组（P〈0．05）;E1组、E3组三磷酸腺苷含量、超氧化物歧化酶活性、心肌线粒体Ca^2＋-ATPase活性、心肌线粒体合成ATP的能力均优于I／R组和E2组（P〈0．05）,丙二醛含量、血清肌酸激酶和乳酸脱氢酶漏出率、心肌细胞内Ca^2＋含量、心肌线粒体Ca^2＋含量低于I／R组、E2组（P〈0．05）;E1组、E3组心肌超微结构损伤较I／R组和E2组明显减轻。结论心肌缺血预处理对未成熟心肌具有明显的保护作用,其机制可能是通过mitoKATP通道的开放起作用。     

前列地尔乳剂对缺血再灌注心肌的保护作用

目的　研究前列地尔脂肪乳剂 (Lipo PGE1)对大鼠心肌缺血再灌注损伤 (MIRI)的影响。方法　应用Langendorff鼠心脏灌注模型 ,将 3 0只SD大鼠随机分成空白对照组 (A组 )、再灌注时K H液加Lipo PGE1组 (B组 )、停跳液中加Lipo PGE1组 (C组 ) ,各组分别平衡灌注 2 0min后灌注冷晶体停搏液 ,2 5℃缺血 5 0min ,再灌注 60min ,观察比较各组心肌I/R前后心率 (HR )、左室发展压 (LVDP)、左室压力变化速率 (△dp/dt)、冠脉流量 (CF)、冠脉流出液中磷酸肌酸激酶 (CPK)、乳酸脱氢酶 (LDH)含量及再灌注后心肌超氧化物歧化酶 (SOD)活性、丙二醛 (MDA)和ATP含量的变化、心肌细胞超微结构的变化。结果　Lipo PGE1改善心肌I/R后的收缩功能、增加冠脉流量和心肌ATP含量 ,促进SOD活性恢复 ,减少心肌细胞CPK和LDH的漏出及MDA的生成 ,减轻了心肌细胞超微结构的损伤。结论　Lipo PGE1通过其抗氧化和扩张冠脉作用可减轻MIRI。     

蛋白激酶C在未成熟心肌预处理中的作用

目的为进一步加强未成熟心肌保护和临床应用的可行性,探讨蛋白激酶C(PKC)在未成熟心肌预处理保护中的作用。方法建立兔Langendorff灌注模型,将24只幼兔随机分为4组:缺血再灌注组(I/R组)、心脏缺血预处理组(MIP组)、PKC阻滞组(CLT组)和PKC激活剂组(PKC组),观察4组幼兔血流动力学、生化、心肌超微结构等指标。结果 MIP组和PKC组心功能恢复、心肌含水量优于I/R组和CLT组(P0.01),三磷酸腺苷(ATP)含量、超氧化物歧化酶活性、心肌线粒体Ca2+-ATPase活性、心肌线粒体合成ATP的能力优于I/R组和CLT组(P0.01),丙二醛含量、血清肌酸激酶和乳酸脱氢酶漏出率、心肌细胞内Ca2+含量、心肌线粒体Ca2+含量低于I/R组和CLT组(P0.01),心肌超微结构损伤较I/R组和CLT组明显减轻。结论心肌缺血预处理对未成熟心肌具有明显的保护作用,其机制可能是通过PKC的激活起作用。     

缺Ca2+预处理对培养乳鼠心肌细胞模拟缺血再灌注的保护作用

目的通过观察短暂缺血预处理(IPC)及缺Ca2+预处理(CPC)对缺血再灌注培养心肌细胞的保护作用及蛋白激酶C活性的影响,探讨CPC的保护作用及机制.方法培养心肌细胞分别经短暂缺血、缺Ca2+及1-(5-异喹啉硫酰)-2-甲基哌嗪(H7)预处理,行模拟缺血30min再灌注10min,测定心肌细胞ATP含量及LDH漏出量;以特异性多肽GS为底物,通过测定掺入多肽GS的γ-32P-ATP放射性活性计算PKC的活性.结果 IPC及CPC都可明显减少心肌细胞ATP消耗及LDH漏出(P<0.01),ATP含量升高分别为(2.80±0.13)、(2.73±0.19)nmol/g;LDH漏出减少,分别为(140.10±18.30)、(164.00±17.30)U/L.无Ca2+/复Ca2+处理后心肌细胞PKC活性为(77.9±28.5)λB*pmol-1*min-1*10-6个),模拟缺血再灌注后PKC活性明显上升(P<0.01),且IPC组和CPC组两者作用相近.而H7则抑制预处理的保护作用及PKC的激活.结论缺血及缺Ca2+预处理可诱导同等强度的心肌细胞保护能力,PKC可能在预处理中起着介导共同通路作用.     

金属硫蛋白对供心的保护作用

目的探讨金属硫蛋白(MT)对离体心脏的保护作用。方法16只Wistar大鼠,随机分为2组,对照组腹腔注射蒸馏水0.5ml,24h后取离体心脏行离体灌注(Langendorff模型),测定心功能,然后灌注HTK心脏保护液,4℃下保存3h,再行Langendorff灌注,10min后转为工作心模型15min;实验组腹腔注射36g/LZnSO4(1.5ml/kg),24h后取离体心脏,随后的处理同对照组。测定心肌组织中MT、ATP、丙二醛(MDA)及Ca2 的含量以及超氧化物歧化酶(SOD)的活性,测定心功能指标、心肌含水量(MWC)、心肌肌酸激酶(CK)和乳酸脱氢酶(LDH)漏出率;测定心肌细胞线粒体内Ca2 ATPase活性、Ca2 含量及其合成ATP能力;观察心肌超微结构。结果实验组MT的含量明显高于对照组(P<0.01);实验组心功能指标、心肌组织中ATP含量及SOD活性均优于对照组(P<0.05,P<0.01),实验组MWC、MDA和Ca2 的含量以及CK、LDH漏出率均低于对照组(P<0.05,P<0.01);实验组心肌细胞线粒体内Ca2 ATPase活性及合成ATP能力均优于对照组(P<0.01),Ca2 含量低于对照组(P<0.01);实验组心肌细胞超微结构的损伤较对照组明显减轻。结论MT对鼠离体心脏具有保护作用。     

肾缺血预处理对未成熟心肌的保护作用

目的探讨肾缺血预处理对未成熟心肌保护的影响，为未成熟心肌的保护提供新的方法。方法建立兔Langendorff灌注模型，将18只幼兔随机分为3组，缺血／再灌注组（I／R组）：灌注15min转为工作心15min，停灌45min，恢复灌注15min改为工作心30min；心脏缺血预处理组（CIP组）：灌注15min转为工作心15min，反复2次缺血5min再灌注5min，重复I／R组的方法；肾缺血预处理组（RIP组）：反复3次阻断左肾动脉血流5min再灌注5min，取离体心脏，灌注15min转为工作心15min，重复I／R组的方法。观察血流动力学、生化等指标。结果CIP组和RIP组的冠状动脉流量（CF）、心排血量（CO）、左心室收缩压（LVSP）恢复百分率均较I／R组升高，左心室舒张期末压（LVEDP）恢复率则较I／R组降低，差异有统计学意义（P〈0.01）；三组间比较，HR、AF恢复率差异无统计学意义（P〉0.05）；RIP组与CIP组比较各指标恢复率差异无统计学意义（P〉0．05）。RIP组与I／R组比较：心肌含水量（MWC）、血清肌酸激酶（cK）和乳酸脱氢酶（LDH）漏出率、ATP含量、丙二醛（MDA）含量、超氧化物歧化酶（SOD）活性、心肌细胞内Ca^2＋含量、心肌线粒体Ca^2＋-ATPase活性、心肌线粒体Ca^2＋含量、心肌线粒体合成ATP能力差异有统计学意义（P〈0.01），RIP组和CIP组比较各项指标差异无统计学意义（P〉0.05）。结论肾缺血预处理对未成熟心肌具有心肌保护作用。     

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.     

A Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

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.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

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.     

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.     

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.