复合磷酸钙骨水泥(CCPC)强化股骨颈空心螺钉扭转刚度的研究

目的评价加压空心螺钉固定时添加复合磷酸钙骨水泥(CCPC)对骨质疏松股骨颈扭转刚度的影响。方法采用16具股骨上段标本,随机分为两组:强化组和非强化组。非强化组进行加压空心螺钉内固定,强化组在进行同样内固定前,先灌入CCPC,置两组标本于NJ-50B型扭转机上,测定扭转10°、30°、90°时的扭转刚度。结果CCPC强化可显著增大空心螺钉扭转刚度,扭转角度为10°时的力矩由灌注前的(5.59±0.27)N·m升至灌注后(5.85±0.26)N·m;扭转角度为30°时的力矩,由灌注前的(6.00±0.15N·m升至(6.20±0.11)N·m,两组有显著性差异(P<0.01)。结论加压空心螺钉固定骨质疏松股骨颈时用CCPC强化能显著提高扭转刚度。     

二种胰肠吻合术吻合口创伤愈合的实验研究

目的　观察比较两种胰肠吻合方法创伤愈合过程。　方法　按吻合方法不同将动物分为捆绑式胰肠吻合组 (Ⅰ组 )和套入式胰肠端端吻合组 (Ⅱ组 ) ,分别在术中、术后 5、10d活体测定吻合口破裂压和离断力 ,并做病理观察。　结果　 (1)破裂压 :Ⅰ组 ,0、5、10d分别为 (139 7± 8 0 )mmHg、(178 7± 9 7)mmHg和 (2 6 8 8± 12 8)mmHg ,Ⅱ组则为 (6 7 3± 7 9)mmHg、(96 2± 10 4 )mmHg和 (130 6± 9 3)mmHg。Ⅰ组和Ⅱ组在 0至 5d和 5至 10d两时间段分别增加 2 7 9%、5 0 5 %和 4 2 9%、35 7% ,两组间在 0、5、10d时差异具有非常显著性 (P <0 0 1)。 (2 )离断力 :Ⅰ组 ,0、5、10d分别为 (4 5± 0 4 )N、(6 6± 0 4 )N和 (10 0± 0 6 )N ;Ⅱ组为 (4 6± 0 6 )N、(5 8± 0 5 )和 (7 1± 0 6 )N。两组在 0天时基本相同 ,但Ⅰ组在 0至 5d和 5至 10d两时间段有较快增长(44 8%和 5 2 9% ) ,两组间在 5、10d时差异具有显著和非常显著性 (P <0 0 5和P <0 0 1)。 (3)组织病理学 :Ⅰ组在 10d时吻合口已由结缔组织基本修复 ,胰腺残端断面已基本由黏膜上皮覆盖。而Ⅱ组则由肉芽组织不完全修复 ,胰腺残端断面尚无上皮再生。　结论　捆绑组 (Ⅰ组 )吻合口强度更强 ,愈合更快。     

卵巢早衰与自然绝经妇女骨密度的对比观察

目的　比较卵巢早衰 (POF)与自然绝经妇女的骨密度 (BMD)。方法　 6 3例经DEXA确诊为骨质疏松的病人分为两组 :2 9例POF为A组 ,年龄 4 8～ 76岁 (6 2 1± 7 0 ) ;34例自然绝经妇女为B组 ,年龄 5 2～ 77岁 (6 3 4± 6 0 )。应用美国Hologic公司QDR4 5 0 0 W型双能X线骨密度仪测定A组和B组腰椎及股骨颈BMD。结果　A、B两组腰椎 2 4、股骨颈BMD相比 ,有显著性差异 (P <0 0 5 )。结论　POF比自然绝经妇女骨量丢失的早并且丢失的多 ,应及早应用HRT。     

SU6668抑制结肠癌生长和转移的实验研究

目的研究血管生成抑制剂SU6 6 6 8对结肠癌生长和转移的抑制作用。方法建立人结肠癌裸鼠原位种植转移模型。将荷瘤鼠 4 8只随机分为四组 ,每组 12只。种植 1周后开始 ,分别自腹腔注射生理盐水 (对照组 )、5 氟脲嘧啶 (5 Fu组 )、SU6 6 6 8制剂 (SU6 6 6 8组 )、5 Fu与SU6 6 6 8联合应用(5 Fu +SU6 6 6 8组 ) ,每天 1次 ,共用 5周。种植后第 6周末处死动物 ,测量原位肿瘤瘤重、抑瘤率、肿瘤微血管密度 (MVD)、结肠癌细胞凋亡指数 (AI) ,观察癌细胞转移及腹水出现情况。结果对照组、5 Fu组、SU6 6 6 8组、5 Fu +SU6 6 6 8组抑瘤率分别为 0、4 2 6 %、80 9%、87 2 % ;MVD分别为 (13 8± 5 2 )、(12 3± 4 5 )、(2 4± 1 5 )、(0 9± 0 5 ) ;AI分别为 (3 6± 2 4 ) %、(7 1± 5 7) %、(11 9± 3 9) %、(19 9±8 6 ) % ;腹膜转移率分别为 10 0 %、4 5 5 %、16 7%、0 ;肝转移率分别为 75 0 %、36 4 %、16 7%、0。故SU6 6 6 8组、5 Fu +SU6 6 6 8组结肠癌生长和转移受到明显抑制 (P <0 0 5 ) ,尤以 5 Fu +SU6 6 6 8组最明显(P <0 0 5 )。结论SU6 6 6 8对结肠癌生长和转移具有较强的抑制作用 ,与传统腹腔化疗药物联用可起协同抑制作用。     

三种不同表面设计的腰椎后路椎间融合器拔出强度的生物力学比较研究

目的　评价不同表面设计的腰椎后路椎间融合器的抗拔出性能。方法　 1 2具男性青壮年新鲜尸体的L3、4节段 ,分 3组模拟后路双侧植入螺纹表面柱状椎间融合器 (Interfix) ,锯齿表面方形融合器 (Prospace)和光滑表面方形融合器 (Syncage)。每组共 4个标本 8枚融合器。在生物力学实验机上通过传感器测定各个融合器的最大拔出力并得出拔出曲线。比较试验结果并进行生物力学评价。结果　三种融合器之间的最大拔出强度分别为 6 95± 1 75N (Interfix) ;2 5 8± 6 5N (Prospace) ;1 30± 34N(Syncage)。三者之间均有统计学差异 (P <0 0 5 )。同时三种融合器的拔出曲线具有不同特征 ,其拔出斜率分别为 1 95 6± 75N/mm、 5 0 4± 2 4N/mm、 1 6 3± 7 4N/mm (按Interfix ,Prospace和Syncage的顺序 ) ,三者之间差异显著 (P <0 0 5 )。 结论　在用于测试的 3种融合器中 ,表面带螺纹的Interfix拔出强度最大 ,表面带连续锯齿的Prospace次之 ,表面光滑的Syncage最差。各融合器的拔出性能与其表面设计有关系     

大鼠两种不同供肝对原位肝移植术中和术后影响的比较

目的　比较正常 (HB)和心跳停搏 (NHB)供肝对大鼠原位肝移植术中和术后的影响。方法　雄性SD大鼠随机分成HB和NHB两组 ;NHB组又分别设心跳停搏 30min(HNB - 30 )和 4 5min(NHB - 4 5 )两组。每组各行原位肝移植 5 0、30和 30次。结果　HB和NHB组冷缺血、无肝期、肝下下腔静脉 (IVC)阻断、受体手术时间分别为 (6 9.76± 1.5 2 )min和 (70 .32± 1.5 3)min、(16 .4 6± 0 .96 )min和(16 .4 0± 0 .73)min、(2 2 .5 6± 1.73)min和 (2 2 .75± 1.16 )min、(89.38± 3.75 )min和 (90 .5 8± 3.76 )min ;术后受体苏醒和主动饮水时间分别为 (5 .4 3± 3.88)min和 (5 4 .0 6± 5 .99)min、(43.0 4± 10 .19)min和(12 6 .79± 15 .0 2 )min ;受体术后鼻粘膜出血率分别为 4 .17%和 92 .6 8% ;受体第 1周体重下降幅度分别为 (6 .15± 1.92 ) %和 (9.6 2± 1.80 ) % ;第 2周体重增加幅度分别为 (7.4 4± 2 .5 9) %和 (3.16± 1.0 4 ) %。HB组近期死因分别为原发性移植肝无功能 (PGF)、麻醉过深、肺部感染和肝上下腔静脉 (SVC)吻合口漏 ;而NHB组分别为PNF、麻醉过深、无肝期较长 (>17min)和再灌注后供肝渗血 ;HB和NHB - 30、NHB - 4 5组术后 1周存活率分别为 90 %、5 0 %和 30 %。结论　NHB较HB术中操作更复杂 ,更需     

腰骶椎弓根螺钉翻修及强化固定后稳定性比较

[目的]从生物力学角度评价腰骶椎弓根螺钉翻修及强化固定的稳定性。[方法]采用7具新鲜成人尸体L5S1椎体标本,于L5椎体首先置入5.5mm/45mm椎弓根螺钉,然后再置入7.0mm/55mm螺钉翻修,最后应用骨水泥强化固定;S1椎弓根置入初始螺钉为6.25mm/35mm、翻修螺钉为8.0mm/45mm、最后同样行骨水泥强化固定。在858MiniMTS生物力学实验机上分别测试各状态轴向最大拔出力及最大扭力矩。[结果](1)在L5,初始、翻修及骨水泥强化固定状态的最大把持力分别为(1680.7±242.8)N、(2410.3±366.1)N、(3273.0±688.5)N(P<0.05),最大扭力矩分别为(1006.1±205.3)N·mm、(1432.6±213.7)N·mm、(590.7±83.5)N·m(P<0.05);(2)在S1,初始、翻修及骨水泥强化的把持力分别为(926.3±274.2)N、(957.5±336.3)N、(1825.3±199.9)N,最大扭力矩分别为(667.6±88.3)N·mm、(681.4±79.4)N·mm、(558.8±97.2)N·mm;其中初始及翻修状态把持力及扭力矩均无明显差别(P>0.05),骨水泥强化固定后把持力明显增加、扭力矩明显减小(P<0.05)。[结论](1)L5椎弓根螺钉翻修时,螺钉直径增加1.5mm、长度增加10mm或骨水泥强化均可达到翻修固定的生物力学要求,增加脊椎稳定性,以骨水泥强化固定更为明显;(2)S1椎弓根螺钉翻修时,单纯增加螺钉直径和长度不能获得理想的稳定性,而骨水泥强化螺钉固定效果明显。     

双加压螺钉治疗股骨颈骨折

我科自 1990年 2月～ 1999年 1月应用电视Ｘ线机下复位 ,空心加压螺钉加折断式加压螺钉固定 ,同时辅助口服复元活血汤治疗股骨颈骨折。通过对84例进行随访 ,疗效满意。1　材料与器械股骨颈空心加压螺钉 ,螺纹直径 6ｍｍ ,螺纹长度 30～ 4 0ｍｍ ,杆长 85～ 12 0ｍｍ(螺距 5ｍｍ) ;折断式加压螺钉 ,螺纹直径 4ｍｍ ,螺纹长度 30～ 35ｍｍ ,杆长 70～ 115ｍｍ(螺距 5ｍｍ)。以上两钉材质相同。与以上固定材料相配套的有套筒旋入器 ,直径 3.5ｍｍ钻头 ,直径 4ｍｍ斯氏针 2枚 ,直径 2ｍｍ等长带刻度的克氏针 2枚等。2　临床资料2 1　一般资料　…     

可降解壳聚糖血管外周支持与静脉移植物早期结构的变化

目的　探讨可降解壳聚糖血管外周支持 (CES)对静脉移植物 (VG)早期结构变化的影响 ,为临床提高VG通畅率提供新的治疗方法。　方法　将兔右颈内静脉端 端吻合于同侧颈总动脉建立静脉移植模型 ,以有无CES干预分为支架组与无支架组 (每组 2 4只兔 )。术后 1、2、4周分别切除移植静脉 ,计算机图像分析系统测量和计算内膜、中膜厚度和面积 ,免疫组织化学法检测增殖细胞核抗原 (PCNA)指数观察平滑肌细胞增殖程度。　结果　CES在术后 2周开始降解。支架组VG ,术后 1～ 2周内膜、中膜的厚度和面积、PCNA指数在术后 1周轻度增加 ,1～ 2周维持稳定 ,术后 2周分别为(2 6 3± 3 7) μm、(2 6 0± 1 9) μm、(0 5 6± 0 0 8)mm2 、(0 34± 0 0 5 )mm2 与 (11 5± 2 1) % ,明显低于无支架组的 (5 6 4± 9 4 ) μm、(47 6± 4 9) μm、(1 17± 0 0 8)mm2 、(1 2 0± 0 4 3)mm2 与 (36 6± 2 9) % (P <0 0 1) ;术后 4周虽然又增加 ,分别为 (31 7± 1 6 ) μm、(31 7± 1 6 ) μm、(0 72± 0 12 )mm2 、(0 4 2± 0 0 6 )mm2 与 (13 4± 1 2 ) % ,但仍低于无支架组的 (76 8± 8 0 ) μm、(5 7 4± 9 5 ) μm、(1 2 7± 0 17)mm2 、(1 2 7± 0 0 9)mm2 与 (16 8± 2 2 ) % (P <0 0 5 )。结论　CES     

毒蕈碱受体亚型介导逼尿肌细胞收缩与IP3关系的实验研究

目的　探讨信使分子IP3 在毒蕈碱受体亚型M3 R介导逼尿肌细胞收缩中的作用。　方法　MR非选择性激动剂 (carbachol)、拮抗剂 (atropine)及M2 R拮抗剂 (methoctramine)、M3 R拮抗剂 (4 DAMP)刺激原代培养人逼尿肌细胞 ,通过 [3 H]掺入法 ,检测磷脂酰肌醇 (PI)代谢产物 [3 H] IP含量。　结果　 [3 H] IP含量随carbachol刺激浓度增加而增加 ;10 -9、10 -8、10 -7、10 -6、10 -5、10 -4mmol/L的 4 DAMP抑制carbachol后 ,[3 H] IP含量分别为 392 6 .5 7± 2 73.2 9、2 780 .5 2± 2 11.0 9、2 4 36 .84± 15 3.6 2、1973.2 2± 16 4 .71、1372 .38± 14 1.35及 110 7.98± 92 0 .4 5cpm ,相同浓度的at ropine作用后 ,[3 H] IP含量分别为 36 0 2 .6 9± 2 80 .17、2 891.31± 2 0 7.4 5、1983.97± 14 5 .74、12 6 9.5 7± 10 5 .31、110 6 .37± 75 .2 3、92 7.5 0± 77.36cpm ;而相同浓度的methoctramine作用后 ,[3 H] IP含量分别为 4 4 6 2 .74± 36 0 .6 9、3938.6 1± 32 7.13、3315 .4 5± 2 70 .36、30 6 3.19± 2 4 6 .79、2 92 7.37± 2 2 6 .4 5及 2 836 .5 5± 2 4 1.6 3cpm ,两者之间差异有非常显著性意义 (P <0 .0 1) ,表明 4 DAMP和atropine能显著抑制carbachol诱导的代谢反应 ,而methoctram     

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 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.     

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.