复合瑞芬太尼时瑞马唑仑用于老年患者全膝关节置换术全麻镇静的半数有效剂量

目的 采用序贯法测定复合瑞芬太尼时瑞马唑仑用于老年患者全膝关节置换术全麻镇静的半数有效剂量（ED₅₀）。
方法 选择择期行单膝全膝关节置换术老年患者29例，男13例，女16例，年龄≥65岁，BMI＜30 kg/m²，ASAⅠ—Ⅲ级。麻醉诱导后行超声引导下股神经阻滞，麻醉维持采用瑞芬太尼0.05～0.20 μg·kg^-1·min^-1，顺式阿曲库铵0.1 mg·kg-1·h-1和瑞马唑仑。根据预试验确定瑞马唑仑的起始剂量为0.7 μg·kg^-1·min^-1，相邻浓度比值为1∶1.15，以出现镇静无效的前一例患者为第1例，按照序贯法确定下一例瑞马唑仑的维持剂量，若上一例镇静有效（BIS≤60、MAP波动幅度<基础值的20%且术后随访无术中知晓），则下一例在上一例的给药剂量基础上降低一个梯度，反之任意一项指标不达标则为镇静无效，下一例给药剂量升高一个梯度，重复此过程直到出现第7个拐点终止研究。采用概率单位Probit回归分析法计算瑞马唑仑的ED₅₀和ED₉₅及其95％可信区间（CI）。记录术中知晓、心动过缓、恶心呕吐等不良反应的发生情况。
结果 瑞马唑仑复合瑞芬太尼联合神经阻滞用于老年全膝关节置换术全麻镇静的ED₅₀为0.539 μg·kg^-1·min^-1（95%CI 0.469～0.604 μg·kg^-1·min^-1），ED₉₅为0.681 μg·kg^-1·min^-1（95%CI 0.611～1.136 μg·kg^-1·min^-1）。1例术中出现窦性心动过缓，给予阿托品有效，1例术后4 h出现恶心呕吐，无一例发生术中知晓和其他不良反应。
结论 复合瑞芬太尼时瑞马唑仑用于老年患者全膝关节置换术全麻镇静的ED₅₀为0.539 μg·kg^-1·min^-1。     

不同剂量瑞马唑仑在老年患者腰-硬联合麻醉术中镇静效果的比较

目的 比较不同剂量瑞马唑仑对腰-硬联合麻醉（CSEA）下行髋关节置换术老年患者术中镇静效果的影响。
方法 选择2021年1—6月在CSEA下行髋关节置换术的老年患者90例，男52例，女38例，年龄65～84岁，BMI 18～31 kg/m²，ASA Ⅰ—Ⅲ级。随机分为三组：瑞马唑仑2 μg·kg^-1·min^-1组（R2组）、瑞马唑仑3 μg·kg^-1·min^-1组（R3组）和瑞马唑仑4 μg·kg^-1·min^-1组（R4组），每组30例。所有患者在L3-4间隙行CSEA，平面固定在T8后，静注瑞马唑仑0.05 mg/kg，R2组、R3组和R4组分别泵注瑞马唑仑2、3、4 μg·kg^-1·min^-1。使用BIS和改良警觉镇静评分（MOAA/S）评分对患者进行镇静评估。当给药后15 min患者MOAA/S评分＞4分，给予瑞马唑仑0.05 mg/kg进行补救，直至MOAA/S≤4分。记录阻滞前、平面固定后、镇静后5、15、30、60 min的BIS值和MOAA/S评分。记录镇静起效时间、补救次数、苏醒时间、术中低氧血症、术后恶心呕吐的发生情况和术后1 d患者满意度情况。
结果 镇静后5、15、30、60 min，R2组BIS和MOAA/S评分明显高于R3组和R4组（P＜0.05）。R2组镇静起效时间明显长于R3组和R4组（P＜0.05），补救次数明显多于R3组和R4组（P＜0.05）。R4组苏醒时间明显长于R2组和R3组（P＜0.05）。三组术中低氧血症发生率差异无统计学意义。R4组恶心呕吐发生率明显高于R2组和R3组（P＜0.05），术后1 d患者非常满意率明显低于R2组和R3组（P＜0.05）。
结论 瑞马唑仑可以安全用于CSEA下髋关节置换术老年患者术中镇静，与泵注瑞马唑仑2 和4 μg·kg^-1·min^-1比较，术中泵注瑞马唑仑3 μg·kg^-1·min^-1镇静效果更好，不良反应更少。     

米库氯铵持续泵注用于腹腔镜胆囊切除术维持深度肌松的半数有效剂量

目的 研究米库氯铵持续泵注用于腹腔镜胆囊切除术中维持深度肌松的半数有效剂量（ED₅₀）。
方法 选择择期行腹腔镜胆囊切除术患者32例，男13例，女19例，年龄18～64岁，BMI 18～30 kg/m²，ASA Ⅰ或Ⅱ级。全麻诱导采用丙泊酚、米库氯铵、麻黄碱、瑞芬太尼，气管插管完成后即刻开始持续静脉泵注米库氯铵，采用肌松监测仪测定术中强直刺激后单次刺激肌颤搐计数（PTC），深度肌松判断标准为PTC≤2。采用改良Dixon上下序贯法设定泵注速度，以9.0 μg·kg^-1·min^-1为起始速率，如果从建立气腹开始至胆囊切除期间能维持PTC≤2，则下一例患者输注速率降低0.5 μg·kg^-1·min^-1，如上述时间段内出现PTC＞2，单次推注米库氯铵0.05 mg/kg补救，并改为术中间断推注米库氯铵维持肌松，下一例患者的输注速率增加0.5 μg·kg^-1·min^-1。采用概率单位回归法（Probit）计算米库氯铵持续泵注维持PTC≤2时的ED₅₀、ED₉₅及其95％可信区间（CI）。记录诱导期间血管活性药物使用情况以及不良反应等。
结果 共纳入32例患者，17例（53%）患者可在建立气腹至胆囊切除期间维持PTC≤2。通过Probit法计算米库氯铵持续泵注用于维持深度肌松的ED₅₀为7.70 μg·kg^-1·min^-1（95%CI 6.66～8.74 μg·kg^-1·min^-1），ED₉₅为14.94 μg·kg^-1·min^-1（95%CI 11.82～18.07 μg·kg^-1·min^-1）。麻醉诱导期间使用去氧肾上腺素患者1例，使用阿托品患者1例，出现胸前区及面部皮肤潮红患者7例。
结论 腹腔镜胆囊切除术中维持深度肌松的米库氯铵持续泵注的ED₅₀为7.70 μg·kg^-1·min^-1。     

联合舒芬太尼时瑞马唑仑抑制气管插管心血管反应的半数有效剂量

目的 评价联合舒芬太尼时瑞马唑仑抑制气管插管心血管反应的半数有效剂量（ED₅₀）。
方法 选择全身麻醉置入单腔气管导管手术患者49例,男29例,女20例,年龄18～64岁,BMI 20～25 kg/m²,ASA Ⅰ或Ⅱ级。首例患者给予瑞马唑仑0.20 mg/kg,待患者意识消失,警觉/镇静评分（OAA/S评分）≤1分且BIS≤60后,给予舒芬太尼0.25 μg/kg,根据上一例患者气管插管心血管反应情况,采用抛偏倚硬币法决定下一例瑞马唑仑剂量。若上一例气管插管心血管反应为阳性,下一例患者瑞马唑仑升高1个剂量梯度;若上一例气管插管心血管反应为阴性,则下一例随机有11%的概率降低瑞马唑仑1个剂量梯度,有89%的概率维持上一例的剂量梯度。设定瑞马唑仑相邻剂量差值为0.01 mg/kg。计算瑞马唑仑抑制气管插管心血管反应的ED₅₀、95%有效剂量（ED₉₅）及其95%可信区间（CI）。
结果 瑞马唑仑抑制气管插管心血管反应的ED₅₀为0.190 mg/kg（95%CI 0.131～0.194 mg/kg）,ED₉₅为0.202 mg/kg（95%CI 0.198～0.220 mg/kg）。
结论 联合舒芬太尼0.25 μg/kg时,瑞马唑仑抑制气管插管心血管反应的ED₅₀为0.190 mg/kg（95%CI 0.131～0.194 mg/kg）。     

复合舒芬太尼时瑞马唑仑抑制老年患者鼻咽通气道置入反应的半数有效剂量

目的 探讨复合舒芬太尼时瑞马唑仑抑制老年患者鼻咽通气道置入反应的半数有效剂量（ED₅₀）。
方法 选择择期在鼻咽通气道下完成白内障手术的老年患者38例，年龄≥65岁，BMI 18～25 kg/m²，ASAⅠ—Ⅲ级。患者依次静脉注射舒芬太尼0.1 μg/kg，3 min后静脉注射瑞马唑仑，2 min后置入鼻咽通气道。首例患者给予瑞马唑仑0.2 mg/kg，采用改良Dixon序贯法确定下一例患者瑞马唑仑的剂量，若前一例患者鼻咽通气道置入时出现以下任意一种阳性反应（摇头、呛咳、体动、HR增快幅度>基础值的20%、SBP或DBP升高幅度>基础值的20%），则下一例麻醉诱导时瑞马唑仑剂量增加0.01 mg/kg，反之则减少0.01 mg/kg，直到出现7次折返后停止。采用Probit回归分析计算复合舒芬太尼时瑞马唑仑抑制老年患者鼻咽通气道置入反应的ED₅₀、95%有效剂量(ED₉₅)及95％可信区间（CI）。
结果 复合舒芬太尼时瑞马唑仑抑制鼻咽通气道置入反应的ED₅₀为0.193 mg/kg（95%CI 0.191～0.195 mg/kg），ED₉₅为0.209 mg/kg（95%CI 0.205～0.213 mg/kg）。
结论复合舒芬太尼时瑞马唑仑抑制老年患者鼻咽通气道置入反应的ED₅₀为0.193 mg/kg（95%CI 0.191～0.195 mg/kg）。     

不同剂量瑞马唑仑用于宫腔镜手术的安全性和有效性

目的 比较三种剂量瑞马唑仑和丙泊酚用于宫腔镜手术的安全性和有效性。
方法 选择择期全麻下行宫腔镜手术患者180例,年龄18~60岁,ASA Ⅰ—Ⅲ级。采用随机数字表法将其分为四组：C组、R1组、R2组和R3组,每组45例。所有患者静脉注射舒芬太尼5 μg后,C组静脉注射丙泊酚1～2 mg/kg进行麻醉诱导,待改良警觉/镇静评分（MOAA/S）为0分后予以5 mg·kg^-1·h^-1静脉泵注维持;R1组、R2组和R3组均静脉泵注瑞马唑仑6 mg·kg^-1·h^-1进行麻醉诱导,MOAA/S为0分后,R1组、R2组和R3组分别调整剂量为0.5、1.0和1.5 mg·kg^-1·h^-1术中维持。记录镇静起效时间、术中补救镇痛例数以及苏醒时间。记录入室平静时（T₀）、麻醉诱导后MOAA/S为0分时（T₁）、术中SBP最低时（T₂）、麻醉苏醒（T₃）后HR、SBP和DBP。记录术中知晓、体动、多巴胺使用例数、呼吸抑制、肌震颤、头痛、注射痛、瘙痒、恶心、呕吐、咳嗽、出汗、寒战和苏醒后眩晕等不良事件的发生情况。
结果 R1组、R2组和R3组镇静起效时间明显长于C组（P＜0.05）,R2组、R3组术中补救镇痛率明显低于R1组（P＜0.05）,R2组和R3组苏醒时间明显长于C组和R1组（P＜0.05）。T₁时R1组、R3组HR明显快于C组（P＜0.05）。T₁、T₂时R1组、R2组和R3组SBP和DBP均明显高于C组（P＜0.05）。R1组术中体动发生率明显高于R2组、R3组（P＜0.05）,R1组、R2组和R3组术中多巴胺使用率和注射痛发生率明显低于C组（P＜0.05）。
结论 以瑞马唑仑6 mg·kg^-1·h^-1静脉诱导、1.0 mg·kg^-1·h^-1麻醉维持应用于宫腔镜手术时相对于应用丙泊酚对循环系统影响更小,注射痛发生率更低,可安全、有效地应用于此类手术患者。     

艾司氯胺酮与右美托咪定在中老年患者全髋关节置换术中的比较

目的 比较艾司氯胺酮与右美托咪定在中老年患者全髋关节置换术中的应用效果。
方法 选择择期行单侧全髋关节置换术的中老年患者60例,男17例,女43例,年龄60～80岁,BMI 18～28 kg/m²,ASA Ⅱ或Ⅲ级。将患者随机分为两组：右美托咪定组（D组,n=30）和艾司氯胺酮组（S组,n=30）。选择L2-3间隙行腰-硬联合麻醉（CSEA）,维持平面T₆—T₁₀。D组：静脉注射咪达唑仑0.04 mg/kg,5 min后静脉注射右美托咪定0.25 μg/kg,后维持0.2～0.7 μg·kg^-1·h^-1。S组：静脉注射咪达唑仑0.04 mg/kg,5 min后静脉注射艾司氯胺酮0.35 mg/kg,后维持0.3～0.4 mg·kg^-1·h^-1。记录入室时、椎管内麻醉10 min后、静注咪达唑仑后10、30、60 min的HR和MAP。记录术中血管活性药物使用情况。记录静注咪达唑仑30、90 min以及开始缝皮时的Ramsay镇静评分。记录术中及术后不良反应的发生情况。
结果 与D组比较,静注咪达唑仑后30、60 min,S组HR明显增快（P＜0.05）,术中麻黄碱、阿托品、去甲肾上腺素的使用率明显降低（P＜0.05）。两组不同时点Ramsay镇静评分、术中及术后不良反应发生率差异均无统计学意义。
结论 艾司氯胺酮与右美托咪定均可安全有效地应用于中老年患者全髋关节置换术,但艾司氯胺酮术中血流动力学更加稳定,且不增加不良反应的发生。     

瑞马唑仑对老年患者腹腔镜术后苏醒质量的影响

目的 探讨瑞马唑仑与丙泊酚用于全麻诱导和维持对老年患者腹腔镜术后苏醒质量的影响。
方法 选择择期在全麻下行腹腔镜手术的老年患者84例，男41例，女43例，年龄65～80岁，BMI 18.5~25.0 kg/m²， ASA Ⅱ或Ⅲ级。采用随机数字表法将患者分为两组：丙泊酚组和瑞马唑仑组，每组42例。麻醉诱导：丙泊酚组静脉注射丙泊酚1～2 mg/kg，瑞马唑仑组静脉注射瑞马唑仑0.15～0.20 mg/kg。麻醉维持：丙泊酚组静脉泵注丙泊酚4～8 mg·kg^-1·h^-1，瑞马唑仑组静脉泵注瑞马唑仑0.5～1.0 mg·kg^-1·h^-1，其余用药相同。记录停药后10、20、30 min的改良警觉镇静评分(MOAA/S)、Steward苏醒评分。分别于麻醉诱导前、术毕即刻、术后24 h抽取肘静脉血，检测血清S100β蛋白、IL-6、丙二醛(MDA)浓度。记录术毕睁眼时间、拔管时间、PACU停留时间。记录术中低血压、注射痛、呛咳、术后恶心呕吐（PONV）等不良反应的发生情况。
结果 与麻醉诱导前比较，两组术毕即刻、术后24 h血清S100β蛋白、IL-6浓度明显升高(P<0.05)，术后24 h血清MDA浓度明显降低(P<0.05)。与丙泊酚组比较，瑞马唑仑组术毕即刻、术后24 h血清S100β蛋白、IL-6浓度明显降低(P<0.05)，睁眼时间明显延长(P<0.05)，注射痛和术中低血压发生率明显降低(P<0.05)。两组停药后10、20、30 min MOAA/S评分、Steward评分、拔管时间、PACU停留时间差异无统计学意义。
结论 丙泊酚与瑞马唑仑对老年患者腹腔镜手术后苏醒质量的影响无明显差异。     

瑞马唑仑和丙泊酚用于肝硬化患者内镜下静脉曲张套扎术的比较

目的 探讨瑞马唑仑和丙泊酚对肝硬化患者内镜下静脉曲张套扎术血流动力学和不良反应的影响。
方法 纳入拟行内镜下静脉曲张套扎术的肝硬化患者96例,男43例,女53例,年龄18～70岁,BMI 18.5～27.9 kg/m²,ASA Ⅱ或Ⅲ级。采用随机数字表法将患者分为两组：瑞马唑仑组（R组）和丙泊酚组（P组）,每组48例。R组静脉注射瑞马唑仑0.2 mg/kg行麻醉诱导,静脉泵注瑞马唑仑1～2 mg·kg^-1·h^-1行麻醉维持;P组静脉注射丙泊酚2 mg/kg行麻醉诱导,静脉泵注丙泊酚4～10 mg·kg^-1·h^-1行麻醉维持。记录麻醉诱导前（T₀）、麻醉诱导后（T₁）、气管插管后（T₂）、手术开始后5 min（T₃）、拔管后（T₄）的HR和MAP。记录患者意识消失时间、拔管时间、意识恢复时间、PACU停留时间。记录术前、术后1 d谷氨酸-丙酮酸转氨酶（ALT）、天门冬氨酸氨基转移酶（AST）。记录术中低血压、术后低氧血症、头晕、恶心呕吐、苏醒延迟、苏醒期躁动的发生情况。
结果 与P组比较,R组T₁—T₃时HR、MAP明显升高（P＜0.05）,意识消失时间明显延长（P＜0.05）,拔管时间、意识恢复时间和PACU停留时间明显缩短（P＜0.05）,术中低血压、术后低氧血症发生率明显降低（P＜0.05）。两组T₀、T₄时HR、MAP差异无统计学意义。两组术后1 d ALT、AST和头晕、恶心呕吐、苏醒延迟、苏醒期躁动发生率差异均无统计学意义。
结论 与丙泊酚比较,瑞马唑仑对行内镜下静脉曲张套扎术肝硬化患者的血流动力学影响较小,可明显降低低血压发生率,安全性较高。     

不同镇静深度下瑞马唑仑对区域麻醉患者外显记忆和内隐记忆的影响

目的 观察瑞马唑仑在不同镇静深度下对区域麻醉手术患者外显记忆（EM）和内隐记忆（IM）的影响。

方法 选择区域麻醉下择期手术患者34例,男19例,女15例,年龄18～64岁,BMI 18～30 kg/m²,ASAⅠ或Ⅱ级。采用随机数字表法将患者分为两组：浅镇静组（M组）和深镇静组（D组）,每组17例。术中以0.1 mg·kg^-1·h^-1的起始剂量持续泵注瑞马唑仑1 mg/ml镇静,以0.1 mg·kg^-1·h^-1的梯度逐渐增加药量,M组维持BIS 60～80,D组维持BIS 40～60,术中在相应范围保持3 min以上,予以听词学习。停药后4～24 h记录简单问卷采访结果,包含测试和排除测试命中率、命中频率。使用加工分离程序（PDP）扩展测试模型评估EM和IM得分。记录镇静过程中托下颌面罩加压给氧,使用麻黄碱、阿托品等干预的不良事件发生情况。

结果 两组简单问卷采访结果无特殊,包含测试和排除测试命中率与命中频率差异无统计学意义。M组EM得分为0.041（-0.015～0.076）,IM得分为0.198（0.043～0.353）。D组EM得分为0.080（0.004～0.151）,IM得分为0.062（-0.003～0.114）。M组IM得分明显大于0（P<0.05）。两组镇静过程中未发生托下颌面罩加压给氧,使用麻黄碱、阿托品等干预的不良事件。

结论 瑞马唑仑在维持BIS 60～80的浅镇静状态下可以消除外显记忆, BIS 40～60的深镇静状态下可以同时消除外显记忆和内隐记忆。     

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.     

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.     

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.     

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.     

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.     

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.     

Systemic analgesia adapted to the children's condition

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.