依普拉芬与17α-炔雌醇合用对去卵巢大鼠子宫和骨的影响

目的观察依普拉芬能否抑制17α-炔雌醇刺激子宫副作用,及对炔雌醇抗骨质疏松作用的影响。方法52只4月龄SD雌性大鼠随机分为6组:①假手术组;②去卵巢组;③高炔雌醇组(30μg·kg-1·d-1);④低炔雌醇组(6μg·kg-1·d-1);⑤依普拉芬(200mg·kg-1·d-1);⑥联合用药组(炔雌醇6μg·kg-1·d-1+依普拉芬200mg·kg-1·d-1)。实验12周,通过测量子宫内膜厚度及子宫湿重分析用药对子宫的刺激作用,测量骨小梁面积百分率(%Tb.Ar)、荧光周长百分数(%L.Pm)及破骨细胞数量(Oc.N分别反映骨量、骨形成及骨吸收的变化)。结果高、低炔雌醇组与去卵巢组比,%Tb.Ar增加,%L.Pm、Oc.N减少,子宫湿重及内膜厚度都显著增加。依普拉芬组与去卵巢组比,子宫湿重及内膜厚度、%Tb.Ar、%L.Pm无显著性差异,Oc.N减少。联合用药组与去卵巢组比,%Tb.Ar增加;与低炔雌醇组比,子宫重量、内膜厚度显著降低,联合用药组与正常对照组的子宫内膜厚度无显著性差异。结论依普拉芬可有效抑制炔雌醇对大鼠子宫刺激作用,与炔雌醇合用可有效防治骨质疏松。     

低剂量雌激素与中药联合用药有效防治大鼠去卵巢所致骨质丢失

目的　探讨低剂量雌激素与中药复方壮骨肾宝 (ZGSB)联合用药防治大鼠去卵巢所致的骨质疏松。方法　 4月龄SD大鼠行双侧卵巢切除术 ,建立骨质疏松动物模型。对照组行假手术。每组 8只 ,共分 6组 ,假手术组 (Sham)和去卵巢组 (OVX)均用蒸馏水 (溶剂对照 )灌胃 ,其余分别为 :OVX +1 7α 炔雌醇 1 0 0 μg·kg 1 ·d 1 (高剂量雌激素组 ) ;OVX +1 7α 炔雌醇 30 μg·kg 1 ·d 1 (低剂量雌激素组 ) ;OVX +壮骨肾宝 1 0 0mg·kg 1 ·d 1 ;(壮骨肾宝组 )和OVX +1 7α 炔雌醇 30 μg·kg 1 ·d 1 +壮骨肾宝 1 0 0mg·kg 1 ·d 1 (联合用药组 ) ,灌胃给药。所有动物给药时间为 1 0周 ,实验结束前 ,行体内双荧光标记 ,实验结束后 ,取胫骨近端松质骨不脱钙硬组织包埋 ,用骨组织形态计量学对骨的静态参数和动态参数进行图像分析及统计。结果　去卵巢后大鼠体重增加 ,子宫重量减轻 ,骨量减少 ,呈现高转换型的骨质疏松表现。雌激素高、低两组均可对抗去卵巢后出现的骨质疏松 ,但低剂量组作用较弱 ,两组均有刺激子宫作用。壮骨肾宝能部分增加去卵巢后大鼠的骨量 ,以促进骨合成为主 ,对破骨细胞的抑制作用较弱。低剂量雌激素与壮骨肾宝联合用药预防去卵巢大鼠骨质疏松的作用较佳 ,比单用雌激素或单用中药的效果明显 ,骨     

人参水煎剂防治去卵巢大鼠骨量丢失的骨形态计量学观察

目的 探讨人参水煎剂对去卵巢大鼠骨量丢失的骨形态学改变及其预防作用。方法4.5月龄SD雌性大鼠,按体重随机分为基础组、假手术组、去卵巢组、已烯雌酚阳性用药组、人参低剂量用药组、人参高剂量用药组,共给药10周,取胫骨上段骨组织包埋,不脱钙骨切片,用全自动图像分析仪及松质骨形态计量学软件进行测量和分析,观察人参对骨形态计量学参数的影响。结果 去卵巢10周后骨量丢失和破骨细胞活性、骨形成及骨转换率增加,差异有显著性(P<0.01)。低剂量的人参能使骨量增加26.6％,高剂量能使骨量增加35.1％,高低两剂量人参能使大鼠的骨吸收和骨转换率均下降,差异有显著性(P<0.01或0.05),不抑制藕联的骨形成。结论去卵巢大鼠骨量丢失,骨转换率增高,出现明显的骨质疏松;已烯雌酚(10μg·kg-1·d-1)能抑制骨吸收,也抑制骨形成。人参有增加骨量的趋势,增加骨形成,并对子宫无刺激作用,有弱的预防去卵巢大鼠的骨量丢失作用。     

新型雌激素哌嗪雌酚酮对去卵巢小鼠骨代谢及骨生物力学的影响

目的研究哌嗪雌酚酮(piperazinyl estrone,PE)对去卵巢小鼠骨代谢及骨生物力学的影响,并探讨其作用机制。方法70只昆明种雌性小鼠,随机分为7组,Basal组,Ovx组,Ovx+PE 0.5mg.kg-1.d-1组,Ovx+PE 1.0 mg.kg-1.d-1,Ovx+PE 2.0 mg.kg-1.d-1,Ovx+E 0.71mg.kg-1.d-1灌胃给药共42 d,处死小鼠,采用骨形态计量学、骨生物力学测定哌嗪雌酚酮对去卵巢小鼠的骨量及力学指标的影响。结果去卵巢小鼠骨小梁面积明显减少63%,小鼠股骨结构力学和材料力学指标均呈现显著性降低,表现出骨吸收大于骨形成的高转换型骨质疏松;而哌嗪雌酚酮各剂量组的骨量均有不同程度增加,小鼠股骨的力学参数有不同程度提高;雌酚酮通过明显抑制骨吸收,轻度抑制骨形成增加骨量。结论哌嗪雌酚酮中剂量组(1.0 mg.kg-1.d-1)轻度抑制骨转换增加去卵巢小鼠的骨量,改善去卵巢小鼠股骨的生物力学特性。     

辛伐他汀促进大鼠骨髓基质细胞的成骨分化

目的观察辛伐他汀体内给药对去卵巢大鼠骨髓基质细胞(BMSC)增殖和分化的影响,探讨辛伐他汀的成骨作用机制.方法24只12周龄雌性SD大鼠随机分成4组,每组6只假手术组(G1)和去卵巢组(G2)每天蒸馏水灌胃;去卵巢大鼠10mg·kg-1·d-1辛伐他汀灌胃(G3);去卵巢大鼠20mg·kg-1·d-1辛伐他汀灌胃(G4).实验持续4周,第29天处死所有大鼠取骨髓细胞培养.用Cell Counting Kit-8(CCK-8)法检测成骨细胞的增殖能力;细胞培养第14天用半定量RT-PCR和western blot检测Runx2/Cbfal mRNA和蛋白的表达、第16天检测碱性磷酸酶活性(ALP)和第21天检测茜素红染色.结果辛伐他汀不能促进去卵巢大鼠成骨细胞增殖.G3组和G4组的Runx 2/Cbfa1 mRNA表达水平和ALP活性都显著高于G2组,给药两组之间无显著差别.G4组的Runx 2/Cbfal蛋白表达水平比G2组和G3组显著增加,G2组与G3组无明显差别.茜素红染色表明辛伐他汀能促进成骨细胞的矿化能力,两种剂量组之间无明显差别.结论辛伐他汀体内给药能够促进去卵巢大鼠BMSC向成骨细胞分化,但是不能促进细胞增殖.     

乳铁蛋白对去卵巢大鼠骨密度和骨形态学的影响

目的 观察乳铁蛋白对去卵巢大鼠骨密度、骨组织形态学的影响.方法 50只SD健康雌性大鼠分为假手术组(Sham)10只与去卵巢模型(ovariectomy,OVX)40只,去卵巢大鼠随机分为模型组、雌激素治疗组(0.1 mg*kg-1*周-1)、小剂量乳铁蛋白治疗组、大剂量乳铁蛋白治疗组,每组10只.假手术组和模型组不做治疗.12周后观察大鼠雌激素水平、左侧股骨、脊柱密度及骨组织形态学的改变.结果 小剂量乳铁蛋白治疗组、大剂量乳铁蛋白治疗组大鼠股骨近端、脊柱骨密度值高于模型组(P<0.05),与假手术组及雌激素治疗组接近(P>0.05);骨小梁数目、骨小梁厚度、骨皮质厚度均较模型组明显改善(P<0.05),破骨细胞数较模型组减少(P=0.06).结论 适量乳铁蛋白可减少去卵巢大鼠骨丢失,预防骨质疏松的作用.     

辛伐他汀体内给药部分阻止大鼠去卵巢导致的骨丢失

目的 观察辛伐他汀体内给药对去卵巢大鼠骨量的影响,探讨辛伐他汀的成骨作用机制.方法 24只12周龄雌性SD大鼠随机分成4组,每组6只:假手术组(G1)和去卵巢组(G2)每天蒸馏水灌胃;去卵巢大鼠10 mg·kg-1·d-1辛伐他汀灌胃(G3);去卵巢大鼠20 mg·kg-1·d-1辛伐他汀灌胃(G4).所有实验动物在处死前10 d和4 d分别皮下注射盐酸四环素和钙黄绿素行荧光双标记.实验持续4周,所有大鼠在最后1次灌胃后的第2天被处死,取大鼠右侧股骨用双能X线骨密度仪测量整体和远端骨密度;取右侧胫骨近端进行骨组织形态计量学测定.结果 G2组大鼠骨量显著低于G1组.G3和G4组大鼠股骨整体骨密度和远端骨密度比G2组显著增加;骨小梁相对体积(BV/TV)和骨形成相关参数:荧光周长百分率(%L.Pm)、骨形成率(BFR/BS)和类骨质表面(OS/BS)都显著高于G2组,G3和G4组之间无差别;骨吸收相关参数如破骨细胞数(Oc.N)和骨吸收表面(ES/BS)与G2组无差别.结论 本实验发现辛伐他汀体内给药能够通过促进骨形成部分阻止去卵巢大鼠骨量丢失.     

小剂量氯胺酮复合芬太尼术后静脉镇痛

目的　比较小剂量氯胺酮联合芬太尼与单纯芬太尼术后静脉镇痛的临床效应。方法选择行上腹部手术后患者 12 0例 ,随机均分为三组 ,每组 4 0例 ,以一次性静脉镇痛泵 (2ml/h)分别行静脉术后镇痛。F组 :单纯芬太尼镇痛 ,0 4 μg·kg-1·h-1芬太尼 +5mg氟哌利多。KF1组 :氯胺酮联合芬太尼镇痛 ,0 2 μg·kg-1·h-1芬太尼 +40 μg·kg-1·h-1氯胺酮 +5mg氟哌利多。KF2组 :氯胺酮联合芬太尼镇痛 ,0 2 μg·kg-1·h-1芬太尼 +80 μg·kg-1·h-1氯胺酮 +5mg氟哌利多。各组镇痛泵中药物均用医用盐水稀释至 10 0ml。观察各组患者镇痛 4 8小时内的静息镇痛评分 (VAS方法 )、恶心呕吐、皮肤瘙痒、尿潴留和幻觉的发生情况。结果　三组患者的静息镇痛评分在 12小时内KF1组和KF2组明显低于F组 (P <0 0 5 ) ,而在 12小时后没有明显差别 (P >0 0 5 ) ;恶心呕吐、皮肤瘙痒和尿潴留发生率KF1组和KF2组显著低于F组 (P <0 0 1)。KF1组和KF2组之间在静息镇痛评分和并发症发生方面没有明显差别。三组中均无幻觉发生。结论　小剂量氯胺酮用于术后静脉镇痛可明显减少芬太尼的剂量 ,使恶心呕吐、皮肤瘙痒和尿潴留发生率降低 ,镇痛效果明显优于单纯芬太尼术后静脉镇痛     

含辅酶Q10和洛伐他汀的红曲提取物对大鼠胫骨形态的骨计量学观察

目的采用大鼠去卵巢合并D-半乳糖诱导老年性骨质疏松的动物模型来评价从红曲提取含辅酶Q10和洛伐他汀的提取物对胫骨形态的骨计量学作用,并与雌激素己烯雌酚比较。方法 3月龄SPF级雌性SD大鼠,随机分为假手术对照组(CON),去卵巢组(OVX),模型组(MOD),己烯雌酚组(DES)和红曲胶囊组(RYR),连续给药60天。实验结束前第13、14天和第3、4天皮下注射钙黄绿素7 mg·kg-1进行骨荧光标记。实验结束时,取右侧胫骨上段制成不脱钙骨切片,胫骨中段制成不脱钙骨磨片用于骨组织形态计量学研究。结果去卵巢合并皮下注射D-半乳糖可导致大鼠体重增加,胫骨松质骨骨量丢失严重,骨显微结构严重退化,胫骨皮质骨的面积减少;含辅酶Q10和洛伐他汀的红曲提取物可使去卵巢合并D-半乳糖大鼠的体重明显减轻,胫骨松质骨以及胫骨皮质骨的骨丢失明显减轻,骨量、骨微观结构得到明显改善。结论去卵巢合并D-半乳糖可导致大鼠出现老年性骨质疏松,补充含辅酶Q10和洛伐他汀的红曲提取物可改善去卵巢合并D-半乳糖大鼠的胫骨骨丢失,提示该提取物具有减肥及防治骨质疏松的良好的应用前景。     

慢性肾衰竭的营养治疗(下)

4 .1　合理的低蛋白饮食和必需氨基酸 /α -酮酸的补充　对透析前CRF患者 ,应给予合理的低蛋白饮食 ,蛋白摄入量一般为 0 .6～ 0 .8g·kg- 1 ·d- 1 ,不宜过低 ,更不是“越低越好”。如CRF病人血肌酐水平高于 1 .5～ 2 .0md/dL( 1 33～ 1 77μmol/L) ,应考虑开始低蛋白、低磷饮食 ( <90 0mg/d)的治疗。如有可能 ,应加用必需氨基酸 (EAA)或 /和α -酮酸 (α-KA)制剂 (剂量为 0 .1～ 0 .2 g·kg- 1 ·d- 1 )。对糖尿病肾病患者 ,蛋白摄入量可适当放宽 (比非糖尿病病人多 0 .0 5～ 0 .1 g·k- 1 ·d- 1 )。应用适当的动物蛋白和植物蛋白…     

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.     

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.     

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.