不同血浆靶浓度瑞芬太尼对患者异丙酚镇静效应的影响

目的 探讨不同血浆靶浓度瑞芬太尼对患者异丙酚镇静效应的影响.方法 择期拟行腹腔镜胆囊切除术患者80例,性别不限,ASA分级Ⅰ或Ⅱ级,年龄18～60岁,随机分为4组,每组20例.麻醉诱导:Ⅱ～Ⅳ组靶控输注瑞芬太尼,血浆靶浓度分别设为2、4、8 ng/ml,Ⅰ～Ⅳ组均靶控输注异丙酚,初始血浆靶浓度为2μg/ml,随后每间隔1min增加0.5μg/ml,直至BIS值下降至50.患者意识消失时记录BIS值和异丙酚血浆靶浓度,BIS值降至50时记录异丙酚血浆靶浓度及异丙酚总用量.结果 与Ⅰ组比较,Ⅲ组和Ⅳ组患者意识消失时BIS值升高,异丙酚血浆靶浓度降低,BIS值降至50时异丙酚总用量和异丙酚血浆靶浓度降低(P＜0.05).结论 复合异丙酚麻醉时,瑞芬太尼适宜血浆靶浓度为4 ng/ml.     

无肌松药全身麻醉下进行功能性鼻内镜手术的随机对照研究

目的 探讨功能性鼻内镜手术围术期肌松药的合理使用.方法选择2012年10月-2013年3月90例诊断为鼻窦炎拟行功能性鼻内镜手术患者,ASA Ⅰ-Ⅱ级,年龄18-60岁,以随机数字表法随机分为3组：Ⅰ、Ⅱ组按时追加肌松剂,Ⅲ组不追加肌松剂.麻醉诱导：Ⅰ组以芬太尼2 μg/kg,Ⅱ、Ⅲ组以舒芬太尼0.2 μg/kg,3组均以丙泊酚2 mg/kg,罗库溴铵0.6 mg/kg麻醉后行气管插管.麻醉维持：3组均靶控输注（target controlled infusion,TCI）丙泊酚血浆药物浓度3 μg/ml及瑞芬太尼血浆药物浓度4 ng/ml,Ⅰ、Ⅱ组每30 min追加罗库溴铵0.2 mg/kg,3组均于收缩压超过100 mm Hg且持续〉5 min时增加靶控输注瑞芬太尼血浆药物浓度,每次0.5 ng/ml.记录麻醉诱导前、手术开始前即刻、手术开始后10 min和30 min的平均动脉压（MAP）、心率（HR）,记录术野出血评估分级、手术时间、拔管时间、离室时间、术中增加靶控输注瑞芬太尼浓度的病例数.结果 3组患者各时点MAP与诱导前相比均降低（P〈0.05）.Ⅰ组手术开始后10 min的MAP明显高于Ⅱ组和Ⅲ组（P〈0.05）,拔管时间和离室时间Ⅰ、Ⅱ组长于Ⅲ组（P〈0.05）.Ⅰ组患者中增加瑞芬太尼靶控输注浓度的例数（23例）明显多于Ⅱ组（10例）和Ⅲ组（11例）（P〈0.05）.3组术野渗血程度差异无显著性（P〉0.05）.结论功能性鼻内镜手术不依赖完善的肌松,术中提供充分的镇痛可保障手术顺利进行.     

依托咪酯靶控输注在全胸腔镜二尖瓣置换术中的应用

目的观察依托咪酯靶控输注(TCI)在全胸腔镜二尖瓣置换术中的使用效果及安全性。方法选择拟在全胸腔镜下行二尖瓣置换术的风湿性二尖瓣病变患者110例,男48例,女62例,年龄29~55岁,ASAⅡ或Ⅲ级,随机分为依托咪酯TCI组(E组)和丙泊酚TCI组(P组),每组55例。E组使用依托咪酯-舒芬太尼TCI(依托咪酯初始血浆靶浓度为0.2μg/ml,根据BIS值以0.1μg/ml梯度逐步增加,舒芬太尼效应室靶浓度1.0ng/ml)进行麻醉诱导与维持,P组使用丙泊酚-舒芬太尼TCI(丙泊酚初始血浆靶浓度为1.0μg/ml,根据BIS值以0.3μg/ml梯度逐步增加,舒芬太尼效应室靶浓度1.0ng/ml)进行麻醉诱导与维持。记录两组患者诱导期低血压发生情况、诱导期血管活性药物用量、诱导期睫毛反射消失时间、麻醉期舒芬太尼用量、手术时间、体外循环时间、升主动脉阻断时间、入CCU时APACHE II评分、术后24h正性肌力药物评分、术后清醒时间、机械通气时间、CCU停留时间、术后住院时间、记录术前、术后2、6、24h血浆中血糖、乳酸浓度,术前及术后24h血浆皮质醇、醛固酮、ACTH浓度以及术后并发症情况。结果 E组患者诱导期低血压发生率明显低于P组,诱导期去甲肾上腺素用量明显少于P组(P0.05);E组清醒时间、机械通气时间、CCU停留时间、术后住院时间明显短于P组(P0.05);与术前比较,术后2、6、24h两组患者血糖和乳酸浓度明显升高(P0.05),6h达到高峰,24h开始下降,两组患者各时点血糖、乳酸浓度差异无统计学意义;与术前比较,术后24hP组皮质醇浓度明显升高(P0.05);术后24hP组皮质醇和醛固酮浓度明显高于E组(P0.05);两组ACTH浓度差异无统计学意义;E组院内肺部感染发生率明显低于P组(P0.05)。结论依托咪酯靶控输注可以维持麻醉诱导期血流动力学平稳,患者术后恢复时间明显缩短,术后肺部感染发生率明显降低,能安全应用于全胸腔镜二尖瓣置换术。     

右美托咪定对丙泊酚复合瑞芬太尼麻醉下脑功能区手术患者唤醒试验质量的影响

目的 评价右美托咪定对丙泊酚复合瑞芬太尼麻醉下脑功能区手术患者唤醒试验质量的影响.方法 拟行术中唤醒的脑功能区手术患者27例,性别不限,年龄17 ～ 43岁,BMI 20～ 24kg/m2,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将患者随机分为2组∶对照组(C组,n=13)和右美托咪定组(D组,n=14).麻醉诱导后气管插管,麻醉维持:2组均靶控输注丙泊酚和瑞芬太尼,丙泊酚血浆靶浓度3 ～5 μg/ml,调整丙泊酚血浆靶浓度维持BIS值55 ～ 65,瑞芬太尼效应室靶浓度2～6ng/ml.打开硬脑膜后,D组停止输注丙泊酚和瑞芬太尼,经15 min静脉输注右美托咪定负荷量0.3μg/kg,随后以0.2 μg-1·kg·h-1速率维持;C组打开硬脑膜后15 min将丙泊酚血浆靶浓度降至0.5μg/ml,将瑞芬太尼效应室靶浓度降至0.5 ng/ml.记录唤醒时间、唤醒试验期间心血管事件、头痛、躁动、谵妄和术中知晓等的发生情况.结果 所有患者均成功实施唤醒,并顺利完成手术.与C组比较,D组唤醒试验期间高血压、心动过速、头痛和术中知晓的发生率均降低(P＜0.05),唤醒时间差异无统计学意义(P＞0.05),2组未见躁动和谵妄的发生.结论 右美托咪定可提高丙泊酚复合瑞芬太尼麻醉下脑功能区手术患者唤醒试验的质量.     

靶控输注异丙酚复合瑞芬太尼麻醉用于重症肌无力患者胸腺切除术的效果

目的 探讨靶控输注异丙酚复合瑞芬太尼用于重症肌无力患者胸腺切除术的效果.方法 择期拟行胸腺切除术的重症肌无力患者45例,ASA分级Ⅰ或Ⅱ级,年龄16～64岁,体重45～95 kg.麻醉诱导:靶控输注异丙酚(血浆靶浓度4μg/ml)和瑞芬太尼(效应室靶浓度4 ng/ml),2%利多卡因2～3 ml行气管内表面麻醉后行气管插管,机械通气.麻醉维持:靶控输注异丙酚,血浆靶浓度3～5 μg/ml;靶控输注瑞芬太尼,效应室靶浓度3～6 ng/ml.术毕前30 min,静脉注射舒芬太尼0.15μg/kg进行镇痛.记录首次气管插管的成功情况、切皮时患者体动反应情况、苏醒时间、拔除气管导管时间、术毕拔除气管导管情况及心血管事件的发生情况.结果 所有患者均顺利完成气管插管,首次气管插管成功率100%.切皮时无一例患者发生体动反应;苏醒时间1.0～3.2 min;拔除气管导管时间2.6～7.0 min;术毕拔除气管导管率100%.麻醉诱导期间有3例患者发生心动过缓,4例患者发生低血压,对症处理后均恢复正常;术中有3例患者发生心动过缓,对症处理后恢复正常.结论 靶控输注异丙酚复合瑞芬太尼麻醉可安全有效地用于重症肌无力患者胸腺切除手术.     

瑞芬太尼和丙泊酚靶控输注用于老年患者妇科腹腔镜手术麻醉的研究

目的对行妇科腹腔镜手术的不同年龄的患者采用瑞芬太尼、丙泊酚靶控输注进行诱导和维持,观察此麻醉方式的临床疗效。方法60名ASAⅠ～Ⅲ级、行择期妇科腹腔镜手术的患者,分为Ⅰ组（〈65岁）和Ⅱ组（≥65岁）,每组30例。麻醉诱导,Ⅰ组瑞芬太尼靶效应室浓度4 ng/ml,Ⅱ组瑞芬太尼靶浓度2.5 ng/ml,2组丙泊酚血浆靶浓度从2.0μg/ml逐渐升高至意识消失,气管插管后根据脑电双频指数（BIS）和血流动力学参数变化调整丙泊酚和瑞芬太尼的靶浓度。记录患者诱导和维持阶段丙泊酚和瑞芬太尼靶浓度、收缩压（SBP）、舒张压（DBP）、心率（HR）及苏醒时间。结果Ⅱ组患者意识消失时丙泊酚靶血药浓度明显低于Ⅰ组[（2.5±0.4）μg/ml vs（3.2±0.5）μg/ml,t=5.988,P=0.000],维持过程中Ⅱ组平均丙泊酚靶浓度低于Ⅰ组[（2.1±0.5）μg/ml vs（2.7±0.7）μg/ml,t=3.820,P=0.000],维持过程中Ⅱ组瑞芬太尼靶浓度明显低于Ⅰ组[（0.19±0.06）ng/ml vs（0.32±0.06）ng/ml,t=8.391,P=0.000]。2组诱导后SBP明显下降,气管插管后回升,术中维持稳定。2组DBP、HR的波动无统计学意义。2组血管活性药的应用例数差异无显著性。Ⅱ组麻醉恢复时间长于Ⅰ组（P〈0.05）。结论根据监测数据个体化地调整丙泊酚和瑞芬太尼的靶浓度,能够使行妇科腹腔镜手术老年患者的血流动力学波动范围和麻醉深度维持在与中青年近似的水平,但老年患者苏醒时间仍延长。     

靶控输注瑞芬太尼和异丙酚麻醉诱导时镇静催眠效应的相互作用

目的 探讨靶控输注(TCI)瑞芬太尼和异丙酚麻醉诱导时镇静催眠效应的相互作用.方法 择期全麻手术患者32例,ASAⅠ或Ⅱ级,年龄22～63岁,体重指数18～25 kg/m2.采用TCI异丙酚和瑞芬太尼诱导麻醉,随机分为4组(n=8):Ⅰ组单纯TCI异丙酚,Ⅱ组～Ⅳ组TCI瑞芬太尼,血浆靶浓度分别为2、4、6 ng/ml,当瑞芬太尼血浆靶浓度与效应室浓度达平衡时开始TCI异丙酚,异丙酚初始血浆靶浓度均为0.5μg/ml,当异丙酚血浆靶浓度与效应室浓度达平衡时以0.5μg/ml的浓度梯度递增诱导至患者意识消失.每隔3min观察睫毛反射和意识状态,同时抽取桡动脉血样6ml,分别采用反相高效液相色谱法和高效液相色谱-紫外法测定异丙酚和瑞芬太尼血药浓度.采用药效学相互作用模型公式和等辐射法分析两者镇静催眠效应的相互作用.结果 与Ⅰ组比较,Ⅱ组～Ⅳ组睫毛反射消失和意识消失时异丙酚血药浓度降低,而Ⅱ组～Ⅳ组随瑞芬太尼血药浓度升高,异丙酚血药浓度依次降低(P<0.05).睫毛反射消失和意识消失时,异丙酚和瑞芬太尼血药浓度用药效学相互作用模型曲线拟合均优于直线回归(P<0.05).拟合出睫毛反射消失时EC50,prop=2.77μg/ml、EC50,rem=26.67 ng/ml,其等辐射法公式EC prop/2.77+Ecrem/26.67=0.69;意识消失时EC50,prop=3.76μg/ml、EC50,rem=31.56 ng/ml,其等辐射法公式Ecprop/3.76+Ecrem/31.56=0.65.结论 麻醉诱导期间,TCI瑞芬太尼(血浆靶浓度2～6ng/ml)和异丙酚在镇静催眠效应上呈协同作用.     

异丙酚、地氟醚或七氟醚复合瑞芬太尼麻醉对脑功能区手术患者术中唤醒试验的影响

目的 探讨异丙酚、地氟醚或七氟醚复合瑞芬太尼麻醉对脑功能区手术患者术中唤醒试验的影响.方法 择期拟行脑功能区肿瘤切除术患者60例,ASA Ⅰ或Ⅱ级,年龄18～60岁,随机分为3组:异丙酚组(P组)、地氟醚组(D组)及七氟醚组(S组),每组20例.静脉注射依托咪酯0.3mg/kg、芬太尼3 μg/kg、维库溴铵0.1 mg/kg行麻醉诱导,采用1%丁卡因喉头及气管粘膜表面麻醉后行气管插管.P组、D组和S组分别靶控输注异丙酚,血浆靶浓度2.0μg/ml,持续吸入地氟醚、七氟醚1.5 MAC维持麻醉.各组均靶控输注瑞芬太尼,血浆靶浓度2.5 ng/ml,唤醒试验前血浆靶浓度降为0.5 ng/ml,静脉注射曲马多100mg,停用麻醉药,行唤醒试验.记录唤醒时间,观察唤醒试验时躁动及寒颤的发生情况.结果 各组患者唤醒时间差异无统计学意义(P>0.05),P组寒颤发生率较D组和S组高(P<0.05).结论 采用异丙酚、地氟醚或七氟醚复合瑞芬太尼麻醉,脑功能区手术患者术中唤醒时间无差别,地氟醚或七氟醚复合瑞芬太尼麻醉时有关并发症发生率低,更适用于术中唤醒试验.     

不同剂量右美托咪定对丙泊酚复合瑞芬太尼用于整形外科手术患者麻醉效果的影响

目的 评价不同剂量右美托咪定对丙泊酚复合瑞芬太尼用于整形外科手术患者麻醉效果的影响.方法 择期行大面积皮肤瘢痕切除和进行皮瓣转移的手术患者60例,性别不限,年龄18～64岁,体重45 ～ 75 kg,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将患者分为3组(n=20):对照组(C组)、低剂量负荷量右美托咪定组(D1组)和高剂量负荷量右美托咪定组(D2组),D1组和D2组分别于麻醉诱导前10 min静脉输注右美托咪定0.6、1.0μg/kg负荷量,随后以0.4 μg· kg-1·h-1速率静脉输注至手术结束前30 min.麻醉诱导:靶控输注丙泊酚(血浆靶浓度4.0μg/ml)和瑞芬太尼(效应室靶浓度2.0 ng/ml),患者意识消失后静脉注射罗库溴铵0.6 mg/kg,气管插管后,机械通气,麻醉维持:靶控输注丙泊酚(血浆靶浓度2.0 ～ 3.5 μg/ml)和瑞芬太尼(效应室靶浓度1.5 ～ 2.5 ng/ml),维持Narcotrend指数为D级.分别于麻醉前、右美托咪定输注10 min、气管插管前即刻、气管插管后1 min、气管插管后5 min、停止输注右美托咪定、拔除气管导管前即刻、拔除气管导管后1 min、拔除气管导管后5min时记录Narcotrend指数、收缩压(SP)、舒张压(DP)和HR.记录麻醉诱导时间、丙泊酚和瑞芬太尼的用量,记录自主呼吸、定向力恢复和拔除气管导管的时间.拔除气管导管后10 min时行镇静-躁动评分,记录术中窦性心动过缓和麻醉恢复期不良事件的发生情况.结果 与C组比较,D1组和D2组丙泊酚、瑞芬太尼的总用量和拔除气管导管后10 min时镇静-躁动评分、麻醉恢复期恶心、呛咳和躁动的发生率降低,右美托咪定输注10 min时Narcotrend指数和HR降低,D2组麻醉诱导时间缩短(P＜0.05或0.01),D2组术中窦性心动过缓发生率高于C组和D1组(P＜0.05),3组间自主呼吸恢复时间、定向力恢复时间和拔除气管导管时间差异无统计学意义(P＞0.05).D1组和D2组气管插管前后和拔除气管导管前后SP、DP和HR差异无统计学意义(P＞0.05).结论 对于整形外科手术患者,麻醉诱导前静脉输注右美托咪定负荷量0.6 μg/kg,随后以0.4 μg·kg-1 ·h-1速率输注可缩短麻醉诱导时间,减少丙泊酚和瑞芬太尼用量,有效地抑制气管插管和拔除气管导管时的应激反应,降低了不良反应的发生.     

异丙酚麻醉下瑞芬太尼抑制不同年龄老年患者气管插管和切皮反应的半数有效血浆靶浓度

目的 确定异丙酚麻醉下瑞芬太尼抑制不同年龄老年患者气管插管和切皮反应的半数有效血浆靶浓度(EC50).方法 择期全麻老年患者116例,年龄60～79岁,体重39～82 kg,ASA Ⅰ～Ⅲ级,按年龄及刺激不同分为4组,靶控输注异丙酚,待患者意识消失时靶控输注瑞芬太尼,Ⅰ-TI组(60～69岁,n=33)和Ⅱ-TI组(70～79岁,n=31)第1例患者瑞芬太尼初始血浆靶浓度设为3.5 ng/ml,待效应室浓度与血浆靶浓度达平衡后静脉注射维库溴铵0.1 me,/kg,3 min后行气管插管.Ⅰ-SI组(60～69岁,n=26)和Ⅱ-SI组(70～79岁,n=26)第1例患者气管插管后瑞芬太尼初始血浆靶浓度设为2.5 ng/ml,待效应室浓度与血浆靶浓度达平衡后维持10 min,开始切皮,采用改良序贯法进行试验.发生心血管反应的标准:气管插管或切皮后3 min内平均动脉压或心率较气管插管或切皮前的基础值升高超过20%.计算各组EC50及其95%可信区间(CI).结果 Ⅰ-TI组和Ⅱ-TI组瑞芬太尼抑制气管插管反应的EC50及其95%CI分别为2.90(2.76～3.04)ng/ml和3.16(2.90～3.41)ng/ml,差异无统计学意义(P>0.05);Ⅰ-SI组和Ⅱ-SI组瑞芬太尼抑制切皮反应的EC50及95%CI分别为1.90(1.76～2.04)ng/ml和1.77(1.68～1.85)ng/ml,差异无统计学意义(P>0.05);与Ⅰ-TI组比较,Ⅰ-SI组EC50降低(P<0.05);与Ⅱ-TI组比较,Ⅱ-SI组EC50降低(P<0.05).结论 60～69岁患者靶控输注异丙酚至意识消失时瑞芬太尼抑制气管插管和切皮反应的EC50分别为2.90、1.90ng/ml,70～79岁患者分别为3.16、1.77 ng/ml,不随年龄增加而改变.     

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.     

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.