不同速率输注右美托咪定对老年白内障手术患者的镇静效应

目的 观察不同速率输注右美托咪定对老年白内障手术患者球后神经阻滞麻醉下的镇静效应.方法 选择90例60～80岁白内障手术患者,根据应用右美托咪定维持剂量随机均分为右美托咪定Ⅰ组(0.2μg·kg-1·h-1)、Ⅱ组(0.4μg·kg-1·h-1)、Ⅲ组(0.6 μg·kg-1 ·h-1).观察并记录三组患者麻醉前(T0)、神经阻滞完毕即刻(T1)、用药后10 min(T2)、20 min(T3)、30 min(T4)、60 min(T5)的Ramsay评分和MAP、HR、RR、SpO2.结果 T2～T5时各组Ramsay评分高于T0时(P＜0.05),T3～T5时Ⅲ组高于Ⅰ组(P＜0.05).T3～T5时三组HR显著慢于T0时(P＜0.05),以Ⅲ组减慢最明显;T3～T5时三组RR均慢于T0时,但差异无统计学意义;三组间MAP、SpO2差异无统计学意义.结论 静注右美托咪定0.5 μg/kg后以0.2～0.4 μg·kg- 1·h-1维持适合老年白内障手术患者的清醒镇静.     

右美托咪定对颅脑手术全麻苏醒期应激反应的影响

目的 观察右美托咪定对颅脑手术全麻苏醒期机体应激反应的影响.方法 40例ASA Ⅰ或Ⅱ级颅内肿瘤行择期手术患者随机均分为右美托咪定组(D组)和对照组(C组).D组手术结束前30 min微量泵静脉输注右美托咪定1μg/kg,输注时间为15 min;C组不输注右美托咪定.记录两组手术结束前30 min(T1)、手术结束时(T2)及气管导管拔管时(T3) MAP、HR和SpO2.留取静脉血检测T1～T3时血糖、肾素活性及去甲肾上腺素水平.结果 与C组比较,T2、T3时D组MAP明显降低,HR明显减慢(P＜0.01);T2、T3时血糖和肾素活性降低(P＜0.05);T3时去甲肾上腺素明显降低(P＜0.01).结论 右美托咪定能明显抑制颅脑手术患者全麻苏醒期的应激反应,有利于血流动力学的稳定.     

右美托咪定对妇科腹腔镜手术患者麻醉恢复的影响

目的 评价右美托咪定对妇科腹腔镜手术患者麻醉恢复的影响.方法 妇科腹腔镜手术患者60例,随机均分为三组.D1、D2组术毕前30 min分别给予右美托咪定0.4、0.8μg/kg,C组患者给予等量生理盐水.患者均采用静-吸复合麻醉.记录患者入室时(T0)、苏醒时(T1)、拔管时(T2)和离开PACU时(T3)的HR和MAP.记录苏醒时间、拔管时间和离开PACU时间,以及苏醒和拔管时Ramsay镇静评分和Riker躁动评分,术后呕吐、寒战等不良反应,追加芬太尼的例数.结果 D1、D2组拔管时间明显短于C组(P＜0.05).D2组患者恢复期追加芬太尼例数明显少于C组(P＜0.05).苏醒时D2组Ramsay评分明显高于C组和D1组(P＜0.05),Riker评分明显低于C组和D1组(P＜0.05).与T0时比较,T1、T2时C组HR明显增快(P＜0.05);T2时D1组HR明显增快(P＜0.05);D2组HR变化差异无统计学意义;T2时C组MAP显著升高(P＜0.05),且C组和D1组明显高于D2组(P＜0.05);D2组MAP变化差异无统计学意义.结论 妇科腹腔镜手术结束前30 min给予右美托咪定0.8μg/kg可减少术后躁动,血流动力学稳定,不影响恢复时间.     

三种不同剂量右美托咪定对全麻鼻内镜手术围拔管期应激反应的影响

目的 观察三种不同剂量右美托咪定对全麻鼻内镜手术患者围拔管期应激反应的影响,并探讨右美托咪定在围拔管期应用的最佳剂量.方法 100例择期行鼻内镜手术患者,ASA Ⅰ或Ⅱ级,随机均分为D1、D2、D3组和对照组(C组).手术结束前15 min D1、D2、D3组分别泵注右美托咪定0.3、0.6、0.9μg/kg,C组泵注等容量生理盐水,15 min内泵注完毕.记录给予右美托咪定前即刻(T1)、手术结束时(T2)、患者可唤醒时(T3)、拔管时(T4)、拔管后1 min(T5)、5 min(T6)、10 min(T7)的HR、MAP、RPP和心脏指数(CI);检测T1、T2、T4、T6时血浆中肾上腺素(E)、去甲肾上腺素(NE)、血糖(Glu)和皮质醇(Cor)的浓度.记录四组患者唤醒时间和拔管时间,并记录T4时拔管质量评分及T6时Ramsay镇静评分.结果 与T1时比较,T2～T6时D1组和C组MAP明显升高,HR明显增快,RPP、CI均明显增加(P＜0.05),T7时D2组,T6、T7时D3组MAP明显降低、HR明显减慢,RPP、CI明显减少(P＜0.05).与C组和D1组比较,T2～T7时D2组、D3组MAP明显降低,HR明显减慢,CI、RPP明显减少(P＜0.05).D3组苏醒时间和拔管时间均明显长于D1、D2组和C组(P＜0.05).与C组和D1组比较,D2组、D3组拔管质量评分明显降低,Ramsay镇静评分明显升高(P＜0.05).与D2组比较,D3组镇静评分明显升高(P＜0.05).四组患者拔管后未发生呼吸抑制不良反应.与T1时比较,T2、T4、T6时D1组、C组血浆中E、NE、Glu、Cor明显升高(P＜0.05).与C组比较,T2、T4、T6时D2组、D3组血浆中E、NE、Glu、Cor明显降低(P＜0.05).与D1组比较,T4、T6时D2组、D3组血浆中E、NE、Glu、Cor明显降低(P＜0.05).结论 对鼻内镜手术患者术毕前15 min给予0.6μg/kg右美托咪定可有效抑制全麻手术拔管期的应激反应,维持血流动力学的稳定,同时不延长患者苏醒时间和拔管时间.     

右美托咪定对脊柱侧弯矫形术患者全麻诱导和术中唤醒时血流动力学的影响

目的 观察右美托咪定对脊柱侧弯矫形术患者全麻诱导和术中唤醒时血流动力学的影响.方法 择期行脊柱侧弯后路矫形手术患者40例,随机均分为右美托咪定组(D组)和生理盐水组(C组),分别在麻醉诱导前给予0.8μg/kg右美托咪定和等量生理盐水,10 min内输完.术中D组持续泵入右美托咪定0.2μg·kg-1 ·h-1,C组泵入生理盐水.观察麻醉诱导前10 min(T0)、麻醉诱导后3 min(T1)、气管插管后1min(T2)、3 min(T3)以及唤醒开始前即刻(T6)、唤醒试验开始后10min( T5)、15 min(T6)、唤醒时(T7)的SBP、DBP、HR.记录唤醒时间及唤醒期间的出血量.结果 与T0时比较,T1时两组SBP、DBP显著降低,HR显著减慢(P＜0.05),且D组显著高/慢于C组(P＜0.05).T2、T3时D组HR明显慢于C组(P＜0.05).T6、T7时D组SBP、DBP显著低于C组,HR明显慢于C组(P＜0.05).唤醒期间D组出血量显著少于C组(P＜0.01).结论 右美托咪定有助于脊柱侧弯矫形手术患者全麻诱导及术中唤醒时血流动力学的稳定,减少唤醒期间出血,不影响唤醒时间,具有较好的保护效应.     

右美托咪定复合瑞芬太尼在纤维支气管镜引导下经鼻清醒气管插管中的应用

目的 观察右美托咪定复合瑞芬太尼用于困难气道患者纤维支气管镜引导下经鼻清醒气管插管中的安全性及有效性.方法 选择择期手术的困难气道患者40例,随机均分为:右美托咪定复合瑞芬太尼组(D组)和丙泊酚复合瑞芬太尼组(P组).D组给予右美托咪定1μg/kg静脉泵注15 min,同时给予瑞芬太尼0.5 μg/kg静脉泵注3 min;P组给予丙泊酚1.5 mg/kg静脉推注3 min和瑞芬太尼0.5 μg/kg静脉泵注3 min后纤支镜下经鼻插入气管导管.观察并比较两组患者入室时(T0)、给药前(T1)、给药后10 min(T2)、给药结束时(T3)、插管前(T4)、插管时(T5)、插管完成时(T6)、插管完成后1 min(T7)、5 min(T8)的HR、MAP、SpO2和RR;并记录患者插管过程中呛咳、恶心及躁动等不良反应和知晓情况.结果 与T0、T1时比较,T2～T8时两组HR、P组RR均明显减慢(P＜0.05);两组MAP、SpO2明显降低(P＜0.05).与P组比较,T2～T4、T8时D组HR明显减慢(P＜0.05);T2～T7时MAP明显升高(P＜0.05);T2、T3和Ts～T7时SpO2明显升高(P＜0.05);T2～T8时RR明显增快(P＜0.01).D组呛咳、恶心、躁动、插管知晓及SpO2下降发生率明显低于P组(P＜0.05).结论 右美托咪定复合瑞芬太尼或丙泊酚复合瑞芬太尼在纤维支气管镜引导下经鼻清醒气管插管都是安全有效的.与丙泊酚复合瑞芬太尼相比,右美托咪定复合瑞芬太尼可提供更稳定的血流动力学且不良反应发生率低.     

右美托咪定对家兔窦房结细胞动作电位的影响

目的 评价右美托咪定对家兔窦房结细胞动作电位的影响.方法 健康新西兰家兔,雌雄不拘,体重1.5～2.5 kg,开胸取心脏,分离窦房结,60个离体窦房结,采用随机数字表法,将其随机分为6组(n=l0):正常对照组(C组)、0.5 ng/ml右美托咪定组(D1组)、5.0 ng/ml右美托咪定组(D2组)、5.0 ng/ml右美托咪定+α2肾上腺素能受体拮抗剂育亨宾组(D2+Y组)、5.0 ng/ml右美托咪定+非选择性超极化激活环核苷酸门控阳离子电流阻断剂氯化铯组(D2+C组)和50.0 ng/ml右美托咪定组(D3组).6组先用台氏液灌流60 min,C组继续用台氏液灌流40 min,D1组、D2组和D3组分别用含0.5、5.0、50.0 ng/ml右美托咪定灌流40 min,D2+Y组和D2+C组分别用含1 μmol/L育亨宾和2mmol/L氯化铯的台氏液灌流20 min,随后再加入5.0 ng/ml右美托咪定继续灌流20 min.分别于台氏液灌流60 min、育亨宾或氯化铯灌流20 min时和右美托咪定停止灌流时记录最大去极速率(Vmax)、动作电位幅度(APA)、复极化50％的动作电位时程(APD50)、复极化90％的动作电位时程(APD90)、4期自动去极速率(VDD)和起搏放电频率(RPF).结果 与C组比较,D1组、D2组和D3组T2,3时APA、VDD和RPF降低,Dt组、D2组和D3组上述指标依次降低(P＜0.05),4组间Vmax、APD5和APD90差异无统计学意义(P＞0.05).与T1时比较,T2时D2+C组VDD和RPF降低,T3时D2+Y组和D2+C组APA、VDD和RPF降低(P＜0.05),余参数差异无统计学意义(P＞0.05)；与T2时比较,T3时D2+Y组APA、VDD和RPF降低,D2+C组APA降低(P＜0.05),余参数差异无统计学意义(P＞0.05).结论 右美托咪定可呈浓度依赖性地降低家兔窦房结细胞自律性,其机制与抑制超极化激活的环核苷酸门控阳离子电流有关,而与α2肾上腺素能受体无关.     

右美托咪定对老年患者全麻诱导过程中心率变异性的影响

目的探讨右美托咪定对老年患者全麻诱导过程中心率变异性(HRV)的影响。方法选择全麻老年患者50例,随机均分为两组:D组麻醉诱导前给予右美托咪定负荷量0.5μg/kg稀释至20ml泵注,10min输注完毕,再以0.3μg·kg-1·h-1泵注至插管后5min。C组静脉泵注等量生理盐水。记录入室后(T0)、右美托咪定负荷量结束后(T1)、气管插管前(T2)及插管后1min(T3)、3min(T4)、5min(T5)时HRV指标:总频(TP)、低频(LF)、高频(HF)及低频/高频(LF/HF)。结果与T1时比较,D组T3～T5时LF,T4、T5时HF,T5时TP明显升高(P0.05);T3～T5时LF/HF明显降低(P0.05)。与C组比较,T3～T5时D组LF,T2～T5的HF和TP明显升高(P0.05),T1～T5时D组LF/HF明显降低(P0.05)。结论全麻诱导过程中给予右美托咪定能够升高HRV,可以有效地调节交感-迷走神经张力的均衡性,稳定心血管功能。     

小剂量右美托咪定复合丙泊酚在无痛小肠镜诊疗术中的应用

目的 观察小剂量右美托咪定复合丙泊酚在无痛小肠镜诊疗术中应用的安全性和有效性.方法 50例行无痛小肠镜检查的患者,ASAⅠ～Ⅲ级,年龄32～76岁,体重48～73 kg.随机均分为右美托咪定复合丙泊酚麻醉组(D组)、丙泊酚麻醉组(P组).记录给药前(T0)、给药后5min (T1)、10 min (T2)、15 min (T3)、20 min(T4)、30 min (T5)时的HR、MAP、RR、SpO2;记录手术时间、苏醒时间、丙泊酚总用量、不良反应发生率及患者满意度.结果 所有病例均能顺利完成操作,T1～T5时D组HR慢于T0时和P组(P＜0.05);T1、T2时P组MAP高于T0时和D组(P＜0.05),两组RR、SpO2、手术时间、苏醒时间差异无统计学意义;D组丙泊酚总用量、不良反应发生率均明显低于P组(P＜0.05),两组患者满意度差异无统计学意义.结论 静脉注射小剂量右美托咪定能产生一定的镇静作用,麻醉中可节省丙泊酚的用量,并具有良好的安全性.     

不同剂量右美托咪定对琥珀胆碱气管插管时眼内压的影响

目的观察不同剂量右美托咪定对琥珀胆碱气管插管引起的眼内压(IOP)升高的影响。方法选择ASAⅠ或Ⅱ级无眼部疾患的全麻患者60例,随机均分为三组:D1组和D2组,麻醉诱导前10min内分别静脉给予右美托咪定0.4、0.6μg/kg;C组,给予等量生理盐水。监测和记录给予右美托咪定前(基础值,T0)、给予右美托咪定后3min(T1)、麻醉诱导后30s(T2)、给予琥珀胆碱后30s(T3)、气管插管后1min(T4)、2min(T5)、4min(T6)和6min(T7)时的MAP、HR和IOP。结果给予右美托咪定后D2组有2例患者因出现低血压和心动过缓被排除本研究。与T0时比较,T1～T3时D1组和D2组IOP明显降低(P<0.05);C组T3～T7时IOP和T4～T7时MAP明显升高;T4～T6时HR明显增快(P<0.05)。与C组比较,T3～T7时D1、D2组IOP明显降低(P<0.05),T4～T7时D1、D2组MAP明显降低、HR明显减慢(P<0.05)。结论静脉给予右美托咪定0.4、0.6μg/kg可有效预防与琥珀胆碱和气管插管有关的IOP升高,但0.6μg/kg右美托咪定可引起明显的低血压和心动过缓。因此,建议术前应用0.4μg/kg右美托咪定预防IOP升高。     

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.