罗哌卡因和布比卡因对豚鼠心室肌细胞L-型钙电流的影响

目的观察罗哌卡因和布比卡因对豚鼠心室肌细胞L-型钙电流(ICa-L)的影响,探讨其心肌负性肌力作用的机制。方法以急性酶解法获得豚鼠的单个心室肌细胞,用标准的全细胞膜片钳技术记录ICa-L。结果100/μmol/L的罗哌卡因和布比卡因分别使豚鼠心室肌细胞ICa-L峰值降低(37±3)%和(42±5)%,两者比较差异有统计学意义(P<0.05);两种药物均使电流密度-电压曲线上移,但不改变激活ICa-L的电压和曲线的形态。罗哌卡因和布比卡因均呈浓度依赖性阻滞豚鼠心室肌细胞ICa-L,半最大抑制浓度分别为212±38、(161±20)μmol/L。结论罗哌卡因和布比卡因均呈浓度依赖性阻滞豚鼠心室肌细胞ICa-L,可能是其产生心肌负性肌力作用的主要机制。     

氯胺酮对大鼠海马锥体神经元延迟整流钾电流的影响

目的观察氯胺酮对大鼠海马锥体神经元延迟整流钾电流(IK)的影响。方法酶消化法急性分离Wistar大鼠海马锥体神经元,采用全细胞膜片钳技术测定IK。加用不同浓度(10、30、100、300、1000μmol/L)氯胺酮后,计算IK抑制率,建立氯胺酮的浓度-效应曲线,选择30 μmol/L氯胺酮作IK 稳态激活(及失活)曲线。结果10、30、100、300、1 000μmol/L氯胺酮对IK的抑制率分别为(10±4)%、(19±4)%、(31±5)%、(50±7)%、(54±8)%。IC50为(100±18)μmol/L,Hill系数为1.33±0.48。激活曲线的半数最大激活膜电位(V1/2)(1.82±0.20)mV上升到(9.30±1.03)mV(n=8,P<0.05),K从(20.4±2.3)mV移动到(16.6±4.2)mV(P>0.05);失活曲线的V1/2从(-29±4)mV下降到(-73±6) mV(P<0.01),K从(26±6)mV上升到(53±11)mV(P<0.01)。30 μmol/L氯胺酮使IK的稳态激活曲线向去极化方向明显移动;使IK的稳态失活曲线向超极化方向明显移动。结论氯胺酮对IK通道有抑制作用,氯胺酮的对中枢神经系统的作用可能与IK抑制有关。     

下腹部及下肢手术病人罗哌卡因、布比卡因低位硬膜外阻滞的效应比较

罗哌卡因为一新型长效酰胺类局麻药，与布比卡因相比，二者作用强度、起效时间和作用持续时间近似，但前者具有在高浓度时对心脏和中枢神经系统毒性低，低浓度时感觉和运动神经阻滞分离效果较好等特点，目前常用于术后镇痛或分娩镇痛。临床实践中有关罗哌卡因较布比卡因其他一些潜在的优越性，仍有待进一步证实。本研究比较0．5％、0．75％罗哌卡因和布比卡因用于下腹部及下肢手术病人低位硬膜外阻滞效应。     

罗哌卡因和布比卡因对新生大鼠心室肌细胞钠通道电流的影响

罗哌卡因是一种长效的酰胺类局麻药,与布比卡因相比具有心脏毒性小、运动和感觉阻滞更为分离的特点,因而广泛应用于产科麻醉和分娩镇痛。目前有关其心脏毒性的研究结果大多来源于成年人或成年动物,对胎儿及新生儿的心脏毒性如何尚无定论。本研究拟比较不同浓度罗哌卡因和布比卡因对新生大鼠心室肌细胞钠通道电流的影响,为     

罗哌卡因与布比卡因腰麻在肛肠疾病术中应用比较

观察比较小剂量相同浓度罗哌卡因与布比卡因腰麻在肛肠疾病手术中的麻醉效果。将80例ASAI,Ⅱ级肛门直肠部择期手术患者按双盲法随机分为罗哌卡因组和布比卡因组,每组40例。两组腰麻用药分别为0．5％罗哌卡因和0．5％布比卡因,用量均为1．5ml。记录两组感觉阻滞、运动阻滞情况和麻醉各时点血压心率变化及不良反应。结果显示,两组均获得满意的麻醉效果。罗哌卡因组和布比卡因组的运动阻滞起效时间分别为（182．5±26．8）s和（145．7±27．4）S（P〈0．01）,最大运动阻滞时间分别为（12．7±4．2）min和（8．0±3．5）min（P〈0．05）,运动阻滞恢复时间分别为（125．9±32．5）min和（158．8±38．7）min（P〈0．01）,感觉阻滞起效时间、程度、阻滞平面相似,两组均无严重不良反应发生。结果表明,0．5％罗哌卡因腰麻用于肛肠疾病手术,能达到满意的麻醉效果,且安全、运动阻滞程度轻。     

罗哌卡因对交感神经节钠通道电流的抑制作用

目的研究罗哌卡因对交感神经节钠通道电流的影响,探讨交感神经节在局麻药诱发心肌毒性反应中的作用.方法酶消化法急性分离SD大鼠(7～10d)颈上交感神经节细胞,全细胞膜片钳技术记录罗哌卡因对其钠通道电流的影响.结果在钳制电压(Vh)-80mV,刺激电压(Vt)0mV条件下,0.01umol/L罗哌卡因使钠电流峰值降低30.02%(P<0.01),其抑制作用与浓度呈正相关(r=0.99,P<0.01),IC50为2.68μmol/L.钳制电位不同,抑制作用也不同(P<0.01),Vh-60mV时的IC50为1.55μmol/L.1.0μmol/L罗哌卡因使电流-电压曲线峰值电流平均降低30.66%,但不影响其形状;对激活曲线无明显的影响(P>0.05),用药前、后50%的通道激活时的去极化电压(V1/2)分别为-25.2mV、-22.64mV;使稳态失活曲线向超极化方向移动(3.56mV,P<0.01),用药前、后50%的通道灭活时的条件脉冲电压(V1/2)分别为-52.99mV、-56.44mV.结论低于致惊厥浓度的罗哌卡因对交感神经节钠通道电流有明显的抑制作用,且呈浓度及电压依赖性;其抑制作用主要与优先结合钠通道的失活状态而影响钠通道的失活有关.提示交感神经节参与介导了罗哌卡因的心肌毒性反应.     

0.1%罗哌卡因与0.1%布比卡因复合芬太尼硬膜外分娩镇痛

罗哌卡因是一种新型长效酰胺类局麻药 ,其化学结构与布比卡因相似 ,但对中枢神经及心血管毒性明显低于布比卡因[1] 。低浓度时 ,罗哌卡因对感觉和运动神经可呈分离阻滞[2 ] 。本研究拟观察小剂量罗哌卡因合并芬太尼硬膜外持续输注进行分娩镇痛的临床效果 ,并与相同浓度的布比卡因进行比较。资料与方法采用随机、双盲、对照、平行试验。对自愿接受无痛分娩的 6 0例名足月初产妇 ,年龄 2 1～ 31岁 ,ＡＳＡ分级 1～ 2级 ,随机分为 (1)试验组 :罗哌卡因组 (Ｒ组 )和 (2 )对照组 :布比卡因组 (Ｂ组 )。Ｒ组 ,负荷剂量 :罗哌卡因 10ｍｇ 0 1ｍｇ…     

异丙酚、硫喷妥钠对大鼠心肌细胞钙、钾通道电流的影响

目的 研究异丙酚、硫喷妥钠对大鼠心肌细胞钙、钾通道电流的影响。方法 急性分离大鼠心室肌细胞,采用全细胞膜片钳技术,观察不同浓度异丙酚、硫喷妥钠对大鼠心肌细胞L型钙通道电流(I_(Ca))、延迟整流钾通道电流(IK)的作用。结果 随浓度增加,异丙酚和硫喷妥钠对I_(Ca)的抑制作用逐渐增强,与浓度呈正相关,相关系数分别为0.98、0.97(P<0.01),异丙酚、硫喷妥钠的IC_(50)分别为138.8±9.5、102.4±2.0μmol·L~(-1)。50μmol·L~(-1)异丙酚、100μmol·L~(-1)硫喷妥钠并不影响钙通道激活曲线的形态,但使钙通道稳态失活曲线向超极化方向分别移动3、7mV(P<0.05)。50μmol·L~(-1)异丙酚、100μmol·L~(-1)硫喷妥钠使IK降低10％和24％(P<0.01),250μmol·L~(-1)异丙酚、500μmol·L~1硫喷妥钠使IK进一步降低,较基础值下降了18％和46％(P<0.01)。结论 异丙酚、硫喷妥钠呈浓度依赖地抑制大鼠心肌细胞L型I_(Ca),其抑制作用主要与加快钙通道的失活有关,两药对IK也有抑制作用。     

剖宫产术后患者左旋布比卡因、罗哌卡因与布比卡因混合芬太尼硬膜外镇痛的效应

目的 比较左旋布比卡因、罗哌卡因和布比卡因复合芬太尼用于剖宫产术后硬膜外镇痛的效果和副作用。方法 采用随机双盲法,将51例择期行剖宫产术的足月、单胎孕妇分为三组:左旋布比卡因组(L组)、罗哌卡因组(R组)和布比卡因组(B组),每组17例。术后分别采用0.125％左旋布比卡因、0.2％罗哌卡因及0.125％布比卡因复合小剂量芬太尼(2μg·ml-1)行病人自控硬膜外镇痛(PCEA)。观察各组术后48 h内镇痛效果、运动阻滞程度变化以及恶心呕吐、尿潴留等副作用的发生率。结果 三组产妇术后视觉模拟评分、改良Bromage评分比较差异均无显著性(P>0.05)。三组产妇对PCEA的非常满意率差异无显著性(L组88.2％,R组76.5％,B组81.3％,P>0.05)。三组不良反应发生率及排气时间差异无显著性(P>0.05)。结论 0.125％左旋布比卡因混合芬太尼(2μg·ml-1)用于产科术后硬膜外镇痛可获得满意的镇痛效果且无明显毒副作用。     

罗哌卡因与布比卡因用于硬膜外阻滞麻醉效果的Meta分析

目的 评价罗哌卡因在硬膜外阻滞麻醉应用中的效果与安全性. 方法 检索PubMed、中国学术期刊全文等数据库中罗哌卡因与布比卡因在硬膜外阻滞麻醉的对比研究,利用Meta分析专用软件RevMan 5.0进行系统评价,重点分析罗哌卡因与布比卡因在感觉阻滞起效时间、运动阻滞恢复时间以及低血压发生率间的差异. 结果 12项研究纳入Meta分析,其中罗哌卡因组362例,布比卡因组377例.罗哌卡因与布比卡因比较,具有较短的感觉阻滞起效时间(Z=2.24,P=0.02,I2=20.5％,P＞0.05),与运动阻滞恢复时间(Z=5.70,P＜0.01,I2=58.9％,P＞0.05),但两者低血压发生率差别无统计学意义(Z=1.06,P＞0.05,I22=0,P＞0.05).结论 罗哌卡因麻醉效果确切,运动阻滞恢复快,具有较高的硬膜外阻滞麻醉优越性.     

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.     

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.     

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.     

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.