依达拉奉后处理联合远隔缺血后处理对大鼠心肌缺血再灌注损伤的影响

目的 评价依达拉奉后处理联合远隔缺血后处理对大鼠心肌缺血再灌注损伤的影响.方法 健康雄性SD大鼠40只,8周龄,体重250～300 g,采用随机数字表法,将其分为5组(n=8):假手术组(S组)、缺血再灌注组(I/R组)、依达拉奉后处理组(E组)、远隔缺血后处理组(P组)、依达拉奉联合远隔缺血后处理组(EP组).采用结扎左冠状动脉前降支30 min,再灌注180 min制备心肌缺血再灌注模型.E组和EP组再灌注前1 min静脉注射依达拉奉3mg/kg;P组和EP组左冠状动脉结扎20 min时实施远隔后处理:用止血带结扎大鼠双后肢,持续10 min.于心肌缺血再灌注期间记录左心室峰压(LVSP)、左心室舒张末压(LVEDP)、左室内压最大上升速率(+dp/dtmax)、左室内压最大下降速率(-dp/dtmax).结果 与S组比较,其它各组再灌注期间LVSP、+dp/dtmax、-dp/dtmax降低,LVEDP升高(P＜0.05);与I/R组比较,E组、P组及EP组再灌注期间LVSP、+dp/dtmax、-dp/dtmax升高,LVEDP降低(P＜0.05);与E组和P组比较,EP组再灌注期间LVSP、+dp/dtmax、-dp/dtmax升高,LVEDP降低(P＜0.05).结论 依达拉奉后处理联合远隔缺血后处理可减轻心肌缺血再灌注损伤,且效果强于两者单独应用.     

右美托咪定预处理对大鼠心肌缺血-再灌注后心室功能和细胞凋亡的影响

目的探讨右美托咪定预处理对大鼠心肌缺血-再灌注损伤后心室功能和心肌细胞凋亡的影响。方法 30只SD大鼠随机分为三组,右美托咪定组(D组),右美托咪定+育亨宾组(D+Y组)和对照组(IR组),D组给予右美托咪定5μg·kg-1·h-1预处理1h,D+Y组静脉注射育亨宾1mg/kg,10min后按5μg·kg-1·h-1输注右美托咪定1h;IR组仅输注等量生理盐水,建立Langendorff缺血-再灌注模型,每10分钟测定左心室舒张末压(LVEDP)、左心室收缩压(LVSP)、左心室内压最大上升速率、下降速率(±dp/dtmax),计算左心室发展压(LVDP)。60min后取下心脏并以TUNEL检测心肌细胞的凋亡,RT-PCR检测Bcl-2mRNA,Bax mRNA的表达。结果与D组比较,再灌注后不同时点IR组和D+Y组大鼠LVDP、±dp/dtmax、Bcl-2mRNA表达明显降低、LVEDP、Bax mRNA表达明显升高(P0.05)。IR组和D+Y组LVDP、LVEDP、±dp/dtmax、Bcl-2mRNA和Bax mRNA表达差异均无统计学意义。IR组细胞阳性率为(36.1±9.2)%、D+Y组为(38.2±6.5)%,明显高于D组为(24.0±8.3)%(P0.05),而IR组和D+Y组细胞阳性率差异无统计学意义。结论右美托咪定预处理可以显著改善大鼠心肌缺血-再灌注损伤后的心室功能,并且可能通过调控凋亡基因Bcl-2mRNA和促凋亡基因BaxmRNA的表达,减少心肌细胞凋亡。     

线粒体ATP敏感性钾通道在利多卡因预先给药减轻大鼠离体心脏缺血再灌注损伤中的作用

目的 评价线粒体ATP敏感性钾通道在利多卡因预先给药减轻大鼠离体心脏缺血再灌注损伤中的作用.方法 雌性成年Wistar大鼠,体重220～250 g,采用Langendorff装置建立大鼠离体心脏缺血再灌注模型.取模型制备成功的大鼠心脏24个,随机分为3组(n=8):缺血再灌注组(IR组)、利多卡因组(L组)和利多卡因+格列苯脲组(LG组).K-H液平衡灌注10 min后,C组、L组和LG组分别灌注K-H液、含2.5 mg/L利多卡因的K-H液、含2.5 mg/L利多卡因+10μmol/L格列苯脲(线粒体ATP敏感性钾通道阻断剂)的K-H液20 min,然后缺血30 min,再灌注60 min.分别于平衡灌注末(T0)、再灌注15 min(T1)、30 min(T2)、45 min(T3)和60 min(T4)时,记录HR、左心室发展压(LVDP)、左心室内压最大上升速率(+dp/dtmax)和左心室内压最大下降速率(-dp/dtmax).于T0和T4时,收集冠状动脉流出液,测定乳酸脱氢酶(LDH)和肌酸激酶(CK)的活性.于T4时取心尖周围心肌组织,测定Na+-K+-ATP酶和SOD的活性、MDA和Ca2+的含量.结果 与IR组比较,L组HR、LVDP、+dp/dtmax和-dp/dtmax升高,CK和LDH的活性降低,心肌Na+-K+-ATP酶和SOD的活性升高,Ca2+和MDA的含量降低(P＜0.05),LG组上述各指标差异无统计学意义(P＞0.05).与L组比较,LG组HR、LVDP、+dp/dtmax和-dp/dmax.降低,CK和LDH的活性升高,心肌Na+-K+-ATP酶和SOD的活性降低,Ca2+和MDA的含量升高(P＜0.05).结论 利多卡因预先给药减轻大鼠离体心脏缺血再灌注损伤与促进线粒体ATP敏感性钾通道的开放有关.     

右美托咪定预先给药对大鼠肢体缺血-再灌注诱发心肌损伤的影响

目的探讨右美托咪定预先给药对肢体缺血-再灌注大鼠诱发心肌损伤的影响。方法健康清洁级SD大鼠30只,6周龄,体重200~250g,采用随机数字表法,将大鼠分为三组,每组10只:假手术组(S组),仅分离股动脉和股静脉;缺血-再灌注组(IR组);右美托咪定预先给药组(D组)。采用无创微动脉夹夹闭股动脉4h后恢复双后肢血流灌注4h的方法制备动物模型。D组肢体缺血前30min腹腔注射右美托咪定50μg/kg,S组和IR组腹腔注射等容量生理盐水。再灌注结束前15min经颈动脉行左心室插管,测量再灌注4h时各组动物左心室收缩压(LVSP)、左室舒张末压(LVEDP)、左室内压最大上升速率(+dp/dtmax)和左室内压最大下降速(-dp/dtmax)。实验结束时自腹主动脉取血,测定血浆SOD活性和MDA含量。开胸取心肌组织,测定心肌组织SOD活性和MDA含量,光镜下观察心肌病理学改变。结果与S组比较,IR组、D组血浆和心肌组织SOD活性明显降低,MDA含量明显升高(P0.05);与IR组比较,D组血浆和心肌组织SOD活性明显升高,MDA含量明显降低(P0.05)。与S组比较,IR组、D组LVSP、+dp/dtmax、-dp/dtmax明显降低,LVEDP明显升高(P0.05);与IR组比较,D组LVSP、+dp/dtmax、-dp/dtmax明显升高,LVEDP明显降低(P0.05)。与IR组比较,D组心肌病理学结果显示损伤减轻。结论右美托咪定预先给药可减轻大鼠肢体缺血-再灌注诱发的心肌损伤,其机制可能与减轻心肌脂质过氧化反应和改善心肌血流灌注有关。     

丙酮酸乙酯预先给药对大鼠离体心脏缺血再灌注损伤的影响

目的 探讨丙酮酸乙酯预先给药对大鼠离体心脏缺血再灌注损伤的影响.方法 雄性SD大鼠24只,体重250～320 g,3月龄,制备Langendorff主动脉逆行灌注模型.随机分为3组(n=8),对照组(C组):改良的K-H缓冲液持续灌流120 min;缺血再灌注组(IR组)改良的K-H缓冲液平衡灌注30 min后,全心停灌30 min,再灌注60 min;丙酮酸乙酯组(EP组)改良的K-H缓冲液平衡灌注15 min后,再用含2 mmol/L丙酮酸乙酯的改良K-H缓冲液平衡灌注15 min,全心停灌30 min,最后用含2 mmol/L丙酮酸乙酯的改良K-H缓冲液再灌注60 min.记录各组平衡灌注15 min(基础值)、再灌注10、30、60 min的左室收缩峰压(LVSP)、左心室内压上升/下降最大速率(±dp/dtmax )、冠脉流量(CF),再灌注60 min时测定心肌ATP含量、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性及冠状动脉流出液中乳酸脱氢酶(LDH)活性、肌酸激酶(CK)的活性.结果 与C组比较,IR组CF、LVSP、±dp/dtmax、SOD活性、ATP含量降低,MDA含量、CK活性、LDH活性升高(P＜0.05),EP组差异无统计学意义(P＞0.05);与IR组比较,EP组CF、LVSP、±dp/dtmax、SOD活性、ATP含量升高,MDA含量、CK活性、LDH活性降低(P＜0.05).结论 丙酮酸乙酯2 mmol/L预先给药通过提高心肌ATP含量,降低氧化应激反应,可减轻大鼠离体心脏缺血再灌注损伤.     

烟碱预先给药对心肌缺血再灌注大鼠心功能的影响

目的 评价烟碱预先给药对心肌缺血再灌注大鼠心功能的影响.方法 健康成年雄性SD大鼠60只,体重200 ～ 250 g,采用随机数字表法,将其分为3组(n=20)∶假手术组(S组)、心肌缺血再灌注组(IR组)和烟碱预先给药组(N组).S组丝线穿过冠状动脉前降支但不结扎；IR组采用丝线结扎左冠状动脉前降支30 min后再灌注120 min的方法制备大鼠心肌缺血再灌注模型.N组结扎前30 min,经右颈静脉注射烟碱400μg/kg,余操作同IR组,S组和IR组右颈静脉注射等量生理盐水.各组随机取10只大鼠于缺血前(T0)、缺血30 min(T1)和再灌注30 min(T2)、120 min(T3)时经生物机能实验系统记录左心室收缩压(LVSP)、左心室舒张压(LVDP)、左室内压上升/下降最大变化速率(±dp/dtmax)、HR和MAP.各组其余10只大鼠于再灌注60 min时采集右颈动脉血样,采用ELISA法测定血浆肌酸激酶同工酶(CK-MB)活性、心肌肌钙蛋白I(cTnI)和TNF-α浓度.结果 与S组比较,IR组T23时MAP和LVSP、T13时HR、LVDP和±dp/dtmax降低,血浆CK-MB活性、cTnI和TNF-α浓度升高,N组T1-2时LVDP、T1-3时HR和±dp/dtmax降低,血浆CK-MB活性、cTnI和TNF-α浓度升高(P＜0.05)；与IR组比较,N组T3时MAP、HR、LVSP、LVDP和±dp/dtmax升高,血浆CK-MB活性、cTnI和TNF-α浓度降低(P＜0.05).结论 烟碱预先给药通过激活胆碱能抗炎通路,抑制炎性反应,可显著减轻大鼠心肌缺血再灌注损伤,从而改善心功能.     

3-硝基丙酸化学预处理对大鼠离体心脏缺血-再灌注损伤的影响

目的研究3-硝基丙酸(3-NPA)化学预处理对大鼠离体心脏缺血-再灌注损伤的保护作用及其机制。方法16只Wistar大鼠随机分为2组,每组8只。实验组(3-NPA组):腹腔注射3-NPAmg·kg-1预处理24h;对照组(C组):腹腔注射等体积生理盐水。采用Langendorff离体心脏灌流模型,两组行常温缺血30min-再灌注60min模拟心肌缺血-再灌注损伤。观察各组缺血前(基础值)和再灌注后30、60min时心率(HR)、左心室发展压(LVDP)、左心室压力上升和下降最大变化速率(±dp/dtmax),测定再灌注后15min时冠脉流出液肌酸激酶(CK)和乳酸脱氢(LDH)活性,测定再灌注后60min时心肌丙二醛(MDA)含量和超氧化物岐化酶(SOD)活性。结果与C组比较,3-NPA组LVDP、 dp/dtmax再灌注后30、60min、-dp/dtmax再灌注后60min时升高(P<0.01或0.05),HR组间比较差异无统计学意义(P>0.05),灌注后15min时冠脉流出液CK和LDH活性降低,再灌注后60min时心肌SOD活性明显升高,心肌MDA含量降低。结论4mg·kg-13-NPA预处理对大鼠离体心脏缺血-再灌注损伤具有一定的保护作用,其机制可能是减少氧自由基的产生和提高SOD活性。     

心肌细胞缝隙连接蛋白43在线粒体敏感性钾通道介导七氟醚预处理减轻大鼠离体心脏缺血再灌注中的作用

目的 评价心肌细胞缝隙连接蛋白43(Cx43)在线粒体敏感性钾(mito-KATP)通道介导七氟醚预处理减轻大鼠离体心脏缺血再灌注中的作用.方法 健康成年雄性SD大鼠40只,体重200～250 g,采用Langendorff灌注模型进行离体心脏灌注.采用随机数字表法,将心脏随机分为5组(n=8):对照组(C组)、缺血再灌注组(I/R组)、七氟醚预处理组(S组)、七氟醚预处理+5-羟葵酸(5-HD)组(SH组)和5-HD组(H组).采用结扎左冠状动脉前降支(LAD) 30 min,恢复灌注120 min的方法制备心脏缺血再灌注模型.各组平衡灌注10 min;然后C组持续灌注,仅于LAD下穿线而不结扎;I/R组继续灌注30 min后结扎LAD;S组、S+H组和H组结扎LAD前30 min时分别用3％七氟醚预先饱和的K-H液、3％七氟醚预先饱和的K-H液+100 μmol/L 5-HD和K-H液+100 μmol/L 5-HD灌注15 min,然后用K-H液冲洗15 min.分别于给药前(T0)、给药结束即刻(T1)、缺血前即刻(T2)、缺血30 min(T3)和再灌注120 min(T4)时,记录HR、左心室收缩压(LVSP)、左心室舒张压(LVDP)、左心室最大上升速率(+dp/dtmax)和左心室最大下降速率(- dp/dtmax).再灌注结束后,取左心室心肌组织,测定心肌梗死体积,采用免疫组化法测定心肌细胞Cx43表达,采用Western Blot法测定心肌细胞Cx43和磷酸化Cx43(p-Cx43)表达.结果 与C组比较,I/R组、S+H组和H组HR、LVSP、+dp/dtmax和- dp/dtmax降低,LVDP升高,心肌细胞Cx43和p-Cx43表达下调(P＜0.05).与I/R组比较,S组HR、LVSP、+dp/dtmax和- dp/dtmax升高,LVDP和心肌梗死体积降低,心肌细胞Cx43和p-Cx43表达上调(P＜0.05),S+H组和H组各指标差异无统计学意义(P＞0.05).结论 七氟醚预处理可能通过开放mito-KATP通道,促进心肌细胞Cx43磷酸化,减轻大鼠离体心脏缺血再灌注损伤.     

舒芬太尼后处理和七氟醚后处理对大鼠离体心脏缺血再灌注损伤的影响

目的 评价舒芬太尼后处理和七氟醚后处理对大鼠离体心脏缺血再灌注损伤的影响.方法 雄性SD大鼠,体重230～250 g,成功制备Langendorff离体灌注模型的40个心脏随机分为4组(n=10):缺血再灌注组(Ⅰ组)、七氟醚后处理组(Ⅱ组)、舒芬太尼后处理组(Ⅲ组)和七氟醚联合舒芬太尼后处理组(Ⅳ组).采用K-H液平衡灌注(灌注压10 kPa)30 min,全心缺血40 min再灌注120 min.再灌注即刻时Ⅱ组、Ⅲ组和Ⅳ组进行药物后处理15 min:Ⅱ组K-H液中通入3.0%七氟醚,Ⅲ组K-H液中加入100 nmol/L舒芬太尼,Ⅳ组同时进行七氟醚后处理和舒芬太尼后处理.分别于平衡灌注末(基础状态)、再灌注15 min、30 min、60 min、90 min、120 min时记录左室收缩压(LVSP)、左室舒张末压(LVEDP)、左室发展压(LVDP)、左室内压上升最大速率(+dp/dtmax)、左室内压下降最大速率(-dp/dtmax)、心率(HR)和灌脉流量(CF).再灌注5 min时,收集冠脉流出液,测定肌酸激酶(CK)和乳酸脱氢酶(LDH)的活性.再灌注120 min时取心肌组织,测定心肌梗死体积、Bcl-2和Bax的表达水平,并计算Bcl-2和Bax表达的比值(Bcl-2/Bax).结果 与Ⅰ组比较,Ⅱ组、Ⅲ组和Ⅳ组LVSP、LVDP、+dp/dtmax、-dp/dtmax和CF升高,LVEDP和LDH、CK的活性降低,心肌梗死体积缩小,Bcl-2表达上调,Bax表达下调,Bcl-2/Bax升高(P＜0.05或0.01);Ⅱ组、Ⅲ组和Ⅳ组间上述指标差异无统计学意义(P＞0.05).结论 舒芬太尼后处理可减轻大鼠心肌缺血再灌注损伤,联合七氟醚后处理时心肌保护作用并未增加,其心肌保护的机制与上调Bcl-2表达、下调Bax表达从而抑制细胞凋亡有关.     

选择性钠氢通道拮抗剂HOE642对未成熟心肌的保护作用

目的比较选择性钠氢通道(NHE1)拮抗剂HOE642在缺血/再灌注不同阶段(缺血前、缺血中、再灌注期)对未成熟心肌的保护作用。方法建立Langendortt离体心脏灌注模型,32只新西兰幼兔随机分为对照组(组Ⅰ,n=8)和HOE642治疗组(n=24),根据给药时间不同, HOE642治疗组又分为:组Ⅱ(n=8)、组Ⅲ(n=8)和组Ⅳ(n=8)。所有心脏均37℃全心缺血60 min,再灌注60 min。组Ⅱ心脏停跳前采用HOE642预处理15 min;组Ⅲ在St.Thomas停跳液中加入HOE642;组Ⅳ于再灌注最初15 min内的KH缓冲液中加入HOE642。测定再灌注期左室发展压(LVDP)、最大收缩变化率( dp/dtmax)、最大舒张变化率(-dp/dtmax)及冠脉流量(CAF);测定心肌细胞内三磷酸腺苷(ATP)、丙二醛(MDA)及心肌含水量(WC);并用透射电镜观察心肌细胞超微结构改变。结果HOE642各治疗组INDP、 dp/dtmax、-dp/dtmax、CAF恢复率及ATP含量明显高于对照组(P<0.05),MDA、心肌含水量明显低于对照组(P<0.05)。HOE642治疗组之间,组Ⅳ再灌注前15 min时 dp/dtmax、-dp/dtmax恢复率低于组Ⅱ和组Ⅲ(P<0.05),而60 min时CAF恢复率高于组Ⅱ和组Ⅲ(P<0.05);组ⅡATP高于组Ⅲ和组Ⅳ(P<0.05),其余指标差异无统计学意义(P> 0.05)。超微结构显示,HOE642治疗能减轻心肌细胞损伤;而HOE642治疗组间,组Ⅳ损伤程度重于组Ⅱ和组Ⅲ。结论缺血/再灌注不同阶段使用HOE642都能减轻未成熟心肌缺血再灌注损伤,而缺血前使用更利于心脏功能恢复、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.     

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.