右美托咪定对心脏瓣膜置换术患者的心肌保护作用

目的观察右美托咪定对心脏瓣置换术患者的心肌保护作用。方法风湿性心脏病行二尖瓣置换术患者30例,均择期全麻CPB下手术,年龄18~65岁,ASAⅡ或Ⅲ级。采用随机数字表法均分为右美托咪定组(D组)和生理盐水组(C组)。麻醉诱导后D组开始静注右美托咪定0.5μg/kg,然后静脉持续泵入0.5μg·kg-1·h-1至手术结束;C组静注等量生理盐水。记录用药前(T0)、用药后即刻(T1)、切皮后(T2)、劈胸骨后(T3)、CPB前(T4)、停CPB后10min(T5)、手术结束(T6)的MAP和HR。于T0、T5、T6、术后6h(T7)、24h(T8)抽取中心静脉血ELISA法检测心型脂肪酸结合蛋白(H-FABP)、肌酸激酶(CK-MB)、肌钙蛋白I(cTnI)浓度。结果与T0时比较,T2、T3时两组MAP明显升高,T1、T2和T4时D组HR明显减慢,而T5、T6时两组HR明显增快(P0.05)。与C组比较,T3时D组MAP明显降低、T4时MAP明显升高(P0.05),T1~T3时HR明显减慢(P0.05)。与T0时比较,T5~T8时两组血清H-FABP、CK-MB和cTnI浓度明显升高(P0.05)。与C组比较,T5~T8时D组血清H-FABP浓度,T7、T8时CK-MB和cTnI浓度明显降低(P0.05)。结论麻醉诱导后给予0.5μg/kg负荷量右美托咪定,随后持续静脉输注0.5μg·kg-1·h-1,可维持体外循环前血压稳定,减轻CPB至术后24h心肌损伤。     

超声引导下右侧星状神经节阻滞对腹腔镜胃癌根治术患者双侧脑血流的影响

目的观察超声引导下右侧星状神经节阻滞(stellate ganglion block, SGB)对腹腔镜下胃癌根治术患者双侧脑血流的影响。方法选择2017年8月至2019年2月择期行腹腔镜下胃癌根治术患者60例,男31例,女29例,年龄60~80岁,ASAⅡ或Ⅲ级,采用随机数字表法将患者随机分为两组,每组30例:SGB组(S组)和对照组(C组)。S组于麻醉诱导前在超声引导下行右侧SGB,注入0.375%罗哌卡因8 ml,C组注射等容量生理盐水。通过经颅多普勒超声(TCD)记录SGB前(T0)、SGB后5 min(T1)、30 min(T2)、60 min(T3)、手术结束(T4)时双侧大脑中动脉(MCA)平均血流速度(Vm),计算搏动指数(PI)和阻抗指数(RI),同时记录T0-T4时的MAP、HR和CVP。结果与T0时比较,T2-T4时C组双侧Vm、MAP明显降低,双侧PI和RI明显升高(P<0.05);T2-T4时S组双侧Vm明显明显降低(P<0.05),非阻滞侧PI和RI明显升高(P<0.05);T2时S组MAP明显降低(P<0.05)。T3、T4时C组MAP明显低于S组(P<0.05)。结论超声引导右侧星状神经节阻滞可以明显降低阻滞侧颅内动脉血管阻力,增加腹腔镜下胃癌根治术中颅内血流动力学的稳定性。     

全身麻醉联合星状神经节阻滞在显微支撑喉镜手术中的应用

目的:观察星状神经节阻滞对显微支撑喉镜手术血流动力学和术后疼痛的影响.方法:50例显微支撑喉镜手术患者随机分成2组,观察组(S组)在麻醉前5 min行左侧星状神经节阻滞,与对照组(C组)比较全麻诱导前(T0)、插管前(T1)、插管完成后(T2)、显微支撑喉镜置入后即刻(T3)4个时间点的SBP、DBP、HR 和术后12 h、24 h、48的疼痛视觉模拟评分.结果:与T0比较,C组的SBP、DBP、HR在T1时降低,T2、T3时升高(P＜ 0.05);S组的SBP、DBP、HR在T1时降低.C组与S组相比,除DBP在T1时外,其他各时点SBP、DBP及HR有明显差异(P＜ 0.05);疼痛评分C组在12 h、24 h时降低(P＜ 0.05).结论:全身麻醉联合星状神经节阻滞用于显微支撑喉镜手术能提供平稳的血流动力学,并能减轻术后疼痛.     

超声引导下腹直肌鞘神经阻滞在腹膜透析管植入术中的应用

目的观察超声引导下腹直肌鞘神经阻滞在终末期肾病患者腹膜透析管植入术中的麻醉效果。方法选择择期行腹膜透析管置入术终末期肾病患者75例,男38例,女37例,年龄18~65岁,BMI 18.5~24.0 kg/m2,ASAⅢ级,采用随机数字法分为三组,A组:全身麻醉组,麻醉方法为全凭静脉麻醉;B组:腹直肌鞘神经阻滞组,手术侧腹直肌鞘内注射0.5%罗哌卡因15 ml;C组:局部浸润麻醉组,1%利多卡因+0.5%罗哌卡因在手术切口和手术路径进行局部浸润麻醉。记录入室时(T0)、麻醉诱导后10 min(T1)、手术开始即刻(T2)、手术开始后20 min(T3)、手术结束时(T4)的HR和MAP。记录患者术后2、4、8、12、24 h运动VAS评分、Ramsay镇静评分,记录手术时间和不良反应。结果与T0时比较,T1~T3时A组HR明显减慢、MAP明显降低(P0.05);T2、T3时C组HR明显增快、MAP明显升高(P0.05);B组不同时点HR和MAP差异无统计学意义。与T1时比较,T2、T3时C组HR明显增快、MAP明显升高(P0.05),与T2、T3时比较,T4时C组HR明显减慢、MAP明显降低(P0.05)。术后2、4、8、12、24 h B组运动VAS评分明显低于A组和C组(P0.05)。C组术中总体补救镇痛次数明显多于B组(P0.05)。A组和B组手术时间明显短于C组(P0.05)。三组均未发生不良反应。结论超声引导下腹直肌鞘神经阻滞在终末期肾病患者腹膜透析管植入术中麻醉效果确切、无不良反应,值得在临床推广。     

全麻复合高位硬膜外阻滞对冠心病病人肌钙蛋白Ⅰ的影响

目的比较观察冠心病病人行胸部手术时采用全麻复合高位硬膜外阻滞能否减轻心肌的损伤.方法 32例冠心病病人随机分为两组,每组16例,Ⅰ组为安氟醚复合高位硬膜外阻滞;Ⅱ组为单纯安氟醚麻醉.两组病人入室后测心率(HR)、平均动脉压(MAP).Ⅰ组病人在行安氟醚全麻前行T3～4或T4～5硬膜外麻醉,5 min后开始诱导插管,安氟醚全麻;Ⅱ组病人直接行安氟醚全麻.两组病人在诱导前和诱导插管后8 h分别抽取血样测定肌钙蛋白I(cTnI)浓度.结果Ⅰ组病人插管后1、5 min及拔管时HR、MAP比麻醉前低(P＜0.05);Ⅱ组病人比麻醉前高(P＜0.05),两组病人插管后1、5 min及拔管时HR、MAP相比有显著差异(P＜0.05).两组病人插管后8 h cTnI浓度均高于诱导前(P＜0.05),但Ⅰ组插管后8 h cTnI浓度比Ⅱ组为低(P＜0.05).结论全麻复合高位硬膜外阻滞麻醉能够减轻冠心病病人手术期的心肌损伤.     

体外循环及非体外循环冠状动脉搭桥术对血清氧自由基及心肌损伤的影响

目的 探讨体外循环下冠状动脉搭桥术(CABG)与非体外循环冠状动脉搭桥术(OPCABG)对血清氧自由基产量及心肌损伤的影响.方法 选择46例首次择期行CABG的冠心病患者,按是否应用心肺转流(CPB)随机均分为CABG组和OPCABG组.于术前、术后2、6、24 h采集血标本,黄嘌呤氧化酶法测定超氧化物歧化酶(SOD)活性;硫代巴比妥酸(TBA)法测定丙二醛(MDA)含量;Olympus AU1000全自动生化分析仪测定血清磷酸肌酸激酶同工酶(CK-MB);ELISA法测定心肌肌钙蛋白(cTnI)含量.结果 两组间术前各项指标差异无统计学意义.与术前相比,两组术后2、6 h SOD活性明显降低(P＜0.01或P＜0.05),两组术后各时点MDA、CK-MB、eTnI明显升高(P＜0.01或P＜0.05).与CABG组相比,术后2、6 h SOD活性OPCABG组明显增加,术后各时点MDA、CK-MB、cTnI OPCABG组明显降低(P＜0.01或P＜0.05).结论 与CABG相比,OPCABG能显著减少氧自由基产量并减轻对心肌的损伤.     

星状神经节阻滞对老年患者全麻气管插管应激反应的影响

目的 观察星状神经节阻滞(SGB)对全麻气管插管应激反应的影响.方法 择期全麻手术患者(年龄≥65岁)45例,随机分为三组.左侧SGB组(LS组)、右侧SGB组(RS组)和对照组(C组),每组15例.记录各组麻醉前(T_0)、诱导后(T_1)、插管即刻(T_2)、插管后1 min(T_3)、5 min(T_4)的SBP、DBP、HR的变化,并计算RPP;于T_0、T_1时点抽取患者上肢静脉血,检测促肾上腺素皮质激素(ACTH)、皮质醇(Cor和血糖(BG).结果 与T_0时比较,三组SBP、DBP、MAP及RPP在T_1时均明显降低(P<0.01),C组MAP及RPP在T_2时明显升高(P<0.05),LS组HR及RPP在T2时明屁升高(P<0.05).与RS组比较,C组及LS组RPP在T2时明显升高(P<0.05).C组BG在T_4明显升高(P<0.05).围插管期ACTH和Cor未见明显改变.结论 右侧SGB可有效抑制老年患者全麻气管插管时的心血管反应. _0、T_1时点抽取患者上肢静脉血,检测促肾上腺素皮质激素(ACTH)、皮质醇(Cor和血糖(BG).结果 与T_0时比较,三组SBP、DBP、MAP及 PP在T_1时均明显降低(P<0.01),C组MAP及RPP在T_2时明显升高(P<0.05),LS组HR及RPP在T2时明屁升高(P<0.05).与RS组比较,C组及LS组RPP在T2时明显升高(P<0.05).C组BG在T_4明显升高(P<0.05).围插管期ACTH     

右美托咪定对全麻低温心肺转流下冠状动脉旁路移植术围术期的心肌保护作用

目的观察右美托咪定对全麻低温心肺转流(CPB)下冠状动脉旁路移植术患者围术期的心肌保护作用。方法择期行全麻低温CPB下冠状动脉旁路移植术患者80例,男67例,女13例。随机均分为右美托咪定组(A组)和对照组(C组)。在中心静脉置管后,A组静脉泵注右美托咪定4μg·kg-1·h-1持续15min后调节维持剂量0.7μg·kg-1·h-1直到手术结束,C组用同样方案静注等容量生理盐水。记录入室后(T0)、麻醉诱导后(T1)、切皮时(T2)、CPB终止时(T3)和手术结束时(T4)的HR、SBP、DBP和血管活性药物用量。测定T1~T4、术后6h(T5)和术后24h(T6)血浆肌酸激酶同工酶(CK-MB)、心肌肌钙蛋白T(cTnT)、肾上腺素(E)和去甲肾上腺素(NE)浓度。结果与T0时比较,T1时两组HR明显减慢,SBP和DBP明显降低(P0.05)。与T1、T2时比较,T3~T6时两组CK-MB、cTnT、E浓度明显升高(P0.05),T3~T5时A组NE浓度明显下降(P0.05),T6时明显升高(P0.05)。T3~T6时A组CK-MB和cTnT浓度明显低于C组(P0.05)。T3~T5时A组E和NE浓度明显低于C组(P0.05)。两组在围术期均未出现严重不良反应。结论右美托咪定能降低全麻低温CPB下冠状动脉旁路移植术围术期心肌缺血的发生,达到围术期心肌保护的作用。     

七氟醚及丙泊酚对心肌缺血-再灌注损伤的影响

目的 观察七氟醚及丙泊酚对非体外循环下行冠状动脉搭桥术患者心肌功能的影响.方法 60例择期行非体外循环下冠状动脉搭桥术的患者随机均分为七氟醚组(S组)和丙泊酚组(P组).S组从手术开始至缝皮结束时吸入2.3最低肺泡有效浓度七氟醚,P组则靶控泵入3 μg/ml的丙泊酚.检测术前、手术结束时、术后2、4 h血浆心肌肌酸激酶同工酶(CK-MB)、肌钙蛋白I(cTnI)水平,并记录入室前、切皮时、劈胸骨时、手术结束时HR、MAP、CVP及恶性心律失常的发生率.结果 再灌注后两组血浆CK-MB和cTnI水平均升高,且术后2、4 h P组高于S组(P＜0.05).两组间HR、MAP、CVP的差异无统计学意义.结论 七氟醚或丙泊酚缺血预处理对非体外循环下行冠状动脉搭桥术患者心肌均有保护作用,其中七氟醚效果更好.     

异氟醚在非体外循环冠状动脉搭桥术中的心肌保护作用

目的 探讨异氟醚在非体外循环冠状动脉搭桥术(OPCABG)中的心肌保护作用.方法 择期行OPCABG冠心病患者42例,随机均分为异氟醚组和丙泊酚组,观察其术前、术后6、12、24 h血清肌酸激酶-同工酶(CK-MB)、肌钙蛋白I(cTnI)以及白细胞介素-6(IL-6)变化.结果 术后6、12、24 h异氟醚组CK-MB、cTnI均低于丙泊酚组(P＜0.01).术后6、12 h异氟醚组IL-6低于丙泊酚组(P＜0.05或P＜0.01).结论 OPCABG中,异氟醚可改善心肌血供,减少心肌损伤.     

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.     

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.