毒扁豆碱对异氟醚麻醉大鼠炎性反应和认知功能的影响

目的探讨毒扁豆碱对异氟醚麻醉大鼠认知功能的影响及其机制。方法 2月龄SD大鼠80只,随机分为四组,每组20只。对照组(C组)吸入含有30%氧气的空氧混合气体6h;异氟醚组(I组)吸入1.4%的异氟醚6h;毒扁豆碱+异氟醚组(PI组)与毒扁豆碱组(P组)腹腔注射毒扁豆碱100μg/kg,每8小时一次,共3次。首次给药后,PI组吸入1.4%异氟醚6h;P组吸入同浓度载气6h。麻醉结束行动脉血气分析,12h后取海马组织,ELISA法检测TNF-α、IL-1β、IL-6含量,RTPCR法检测capase-3mRNA的表达。光镜下观察海马CA1区锥体细胞形态学变化。麻醉后第2~7天评估认知功能。结果四组大鼠动脉血气指标、血糖和海马TNF-α含量差异均无统计学意义。与C组和P组比较,I组和PI组大鼠海马IL-1β、IL-6含量、capase-3mRNA明显升高,第4~6天逃避潜伏期明显延长,探索时间明显缩短(P0.05)。与I组比较,PI组大鼠海马IL-1β、IL-6含量、caspase-3mRNA表达明显降低,第4~6天逃避潜伏期明显缩短,探索时间明显延长(P0.05)。结论毒扁豆碱改善了异氟醚麻醉引起的大鼠认知功能损害,其机制可能与抑制海马炎性反应及神经元凋亡有关。     

大鼠妊娠前后吸入异氟烷或七氟烷对子代海马NMDA受体表达的影响

目的 探讨大鼠妊娠前后吸入异氟烷或七氟烷对子代海马N-甲基-D-天冬氨酸(NMDA)受体表达的影响.方法 雌性SD大鼠30只,3月龄,体重250～ 300 g,采用随机数字表法,将其分为5组(n=6):对照组(C组)、妊娠前1d吸入1.6％异氟烷6h组(BI组)、妊娠6、10、14和18d时吸入1.6％异氟烷6h组(PI组)、妊娠前吸入2.4％七氟烷6h组(BS组)和妊娠6、10、14和18d吸入2.4％七氟烷6h组(PS组).于出生当天(T1)、出生后第7(T2)、14(T3)和28天(T4)时各组按窝别随机取12只子鼠处死取海马,采用免疫荧光和RT-PCR法检测NMDA受体(NRI、NR2A和NR2B)的表达水平.结果 与C组比较,BI组和BS组子鼠海马NMDA受体表达差异无统计学意义(P＞0.05),PI组和PS组T1-3时子鼠海马NR1和NR2A表达上调,NR2B表达下调,NR1 mRNA和NR2A mRNA表达上调,NR2B mRNA表达下调(P＜0.01),T4时NMDA受体表达差异无统计学意义(P＞0.05);与PI组比较,PS组T1-3时子鼠海马NR1和NR2A表达上调,NR2B表达下调,NR1 mRNA和NR2A mRNA表达上调,NR2B mRNA表达下调(P＜0.05或0.01),T4时NMDA受体表达差异无统计学意义(P＞0.05).结论 妊娠前吸入异氟烷或七氟烷对子鼠海马NMDA受体表达无影响,妊娠后吸入异氟烷或七氟烷可引起子鼠海马NMDA受体表达异常,可能引起子鼠海马神经细胞凋亡和神经系统发育及认知功能异常.     

手术对异氟醚麻醉下老龄大鼠术后认知功能的影响

目的 探讨手术对老龄大鼠异氟醚麻醉下术后认知功能的影响.方法 健康雄性老龄SD大鼠72只,年龄20月,体重500～600 g,随机分为3组(n=24):对照组(C组)、异氟醚麻醉组(I组)和手术组(O组).C组吸入30%氧气2 h,I组吸入1.5%异氟醚和30%氧气的混合气体2 h,O组吸入1.5%异氟醚和30%氧气的混合气体2 h,并实施腹部手术.于麻醉结束后或术后24 h时随机取8只大鼠,取海马组织,采用免疫组织化学法和RT-PCR法分别测定神经元胆碱乙酰转移酶(ChAT)及ChAT mRNA的表达水平,其余大鼠进行Morris水迷宫实验,测定认知功能.结果 与C组比较,I组和O组逃避潜伏期延长,原平台象限停留时间缩短,穿越原平台次数减少,海马神经元ChAT mRNA及其蛋白表达水平降低(P<0.05);与I组比较,O组术后第4、5天逃避潜伏期延长,原平台象限停留时间缩短,海马神经元ChAT mRNA及其蛋白表达水平降低(P<0.05);与麻醉结束后或术后第3天比较,C组第4、5天逃避潜伏期差异无统计学意义(P>0.05),I组和O组逃避潜伏期延长(P<0.05);I组和O组麻醉结束后或术后第4、5天逃避潜伏期差异无统计学意义(P>0.05).结论 手术操作可加重异氟醚引起的老龄大鼠术后认知功能障碍,其机制可能与海马胆碱能神经元受损有关.     

异氟醚麻醉对大鼠海马蛋白质组的影响

目的 研究异氟醚麻醉后大鼠海马蛋白质组的变化.方法 将10只8月龄SD大鼠随机均分为异氟醚组(I组)和对照组(C组).1组大鼠以1.2%异氟醚吸入麻醉2 h,C组吸氧对照.于麻醉处理或吸氧对照结束后24 h取海马组织行双向凝胶电泳和质谱分析以鉴定差异蛋白点.结果 双向凝胶电泳结果显示I和C组差异蛋白质点共有17(4/13)个,MAL DI-TOF-MS分析后鉴定出12种蛋白质.结论 异氟醚麻醉可以引起大鼠海马蛋白质组变化,这些蛋白质变化可能具有一定的神经元保护作用.     

异氟醚麻醉对新生大鼠海马BDNF和磷酸化ERK表达的影响

目的 探讨异氟醚麻醉对新生大鼠海马脑源性神经营养因子(BDNF)和磷酸化细胞外信号调节激酶(p-ERK)表达的影响.方法 出生7d的SD大鼠48只,体重12～17 g,雌雄不拘,采用随机数字表法,将其随机分为2组(n=24):对照组(C组)和异氟醚麻醉组(1组).Ⅰ组吸入2.5％异氟醚3 min,然后吸入1.5％异氟醚4h;C组吸入空气4h.麻醉结束即刻每组取4只大鼠,抽取动脉血样,行血气分析,并检测血糖浓度.分别于麻醉结束即刻和麻醉结束后6、24和48 h(T-4)时各处死大鼠5只,取海马组织,采用Western blot法检测钾离子-氯离子联合转运体2(KCC2)、钠离子-钾离子-氯离子联合转运体1( NKCC1)、BDNF和p-ERK的表达,计算NKCCI/KCC2比值.结果 麻醉结束即刻两组大鼠均未发生酸碱失衡、低氧和低血糖等.与C组比较,Ⅰ组T3和T4时海马KCC2表达下调,NKCC1/KCC2比值升高,T1和T2时海马BDNF和p-ERK的表达下调(P＜0.05),各时点海马NKCC1表达差异无统计学意义(P＞0.05).结论 异氟醚麻醉通过下调BDNF和p-ERK的表达,导致新生大鼠海马神经元发育延迟.     

异氟醚对老龄大鼠海马蛋白质组的影响

目的 探讨异氟醚对老龄大鼠海马蛋白质组的影响.方法 清洁级老龄雌性SD大鼠75只,22月龄,随机分为对照组(C组,n=35)和异氟醚组(I组,n=40).C组吸入含40%氧气的空气2 h,I组通过异氟醚挥发罐的调节使麻醉箱内异氟醚浓度为3%,待翻正反射消失后将异氟醚浓度降至1.2%,维持2 h.I组苏醒后24 h采用Y型迷宫实验检测认知功能,麻醉结束后24 h和72 h分别随机取5只大鼠,取海马行双向凝胶电泳和质谱分析.结果 与c组比较,I组麻醉结束后24 h和48 h正确反应次数和主动回避次数降低,全天总反应时间延长(P＜0.05);学习能力I组低于C组(P＜0.05).2组麻醉结束后24 h差异表达蛋白17种,其中6种蛋白质表达上调,11种蛋白质表达下调;2组麻醉结束后72 h差异表达蛋白16个,其中10种蛋白质表达上调,6种蛋白质表达下调.结论 异氟醚麻醉后早期老龄大鼠认知功能下降具有可逆性,这种现象可能与海马蛋白质组变化有关.     

抗氧化剂MitoQ对异氟醚诱导大鼠海马神经元损伤的影响及机制

目的探讨抗氧化剂MitoQ对异氟醚诱导的新生大鼠海马神经元细胞损伤的影响及潜在机制。方法 SPF级健康SD大鼠15只,7日龄,体重15~20g。采用随机数字表法分为三组:对照组(C组)、异氟醚组(I组)和异氟醚+MitoQ组(IM组),每组5只。C组吸入空-氧混合气体。Ⅰ组于出生后7、14和21d吸入1.5%异氟醚2h,IM组在每次吸入异氟醚前腹腔注射MitoQ0.4ml/kg。于出生后28d采用HE染色观察各组大鼠海马CA1区海马神经元细胞形态。分离培养新生大鼠原代海马神经元细胞培养并分组处理,采用MTT法和TUNEL原位荧光染色法检测细胞存活率和凋亡率;采用硫代巴比妥酸法和黄嘌呤氧化酶法检测细胞中丙二醛(MDA)浓度和超氧化物歧化酶(SOD)活性;采用Rhodamine 123染色荧光显微镜照相法检测线粒体膜电位(MMP),DCFH-DA染色荧光显微镜照相法检测细胞内活性氧簇(ROS)生成量,采用Western blot法检测海马神经元细胞中Bax、Bcl-2和caspase-3蛋白含量。结果与C组比较,Ⅰ组大鼠海马组织神经细胞受损明显,细胞数目减少,Ⅰ组细胞存活率明显降低,细胞凋亡率明显升高,MDA浓度明显升高,SOD活性明显降低,ROS生成量明显增加,MMP水平明显降低,Bax和caspase-3蛋白含量明显升高,Bcl-2蛋白含量明显降低(P0.05);与Ⅰ组比较,IM组大鼠海马组织神经细胞损伤减少,细胞存活率明显升高,细胞凋亡率明显降低,MDA浓度明显降低,SOD活性明显升高,ROS生成量明显减少,MMP水平明显升高,Bax和caspase-3蛋白含量明显降低,Bcl-2蛋白含量明显升高(P0.05)。结论抗氧化剂MitoQ可明显抑制异氟醚诱导的海马神经元细胞损伤,这与其拮抗细胞氧化应激和维持线粒体功能作用密切相关。     

孕早期安氟醚麻醉对大鼠子代海马NR2B表达的影响

目的 评价孕早期安氟醚麻醉对大鼠子代海马N-甲基-D-天冬氨酸受体2B亚基(NR2B)表达的影响.方法 孕8～10 d SD大鼠30只,体重200～250 g,采用随机数字表法,将其随机分为3组(n=10):对照组(C组)、吸入安氟醚4h组(E1组)和吸入安氟醚8h组(E2组).E1组和E2组分别吸入1.7％安氟醚4和8h,氧流量为2 L/min,C组吸入等流量氧气.分别于出生后20和30d,采用Morris水迷宫系统测定子鼠的认知功能.于水迷宫实验结束后第2天,取各组子鼠海马组织,分别采用PCR和免疫组化法测定NR2B mRNA及蛋白的表达.结果 与C组比较,E1组和E2组子鼠出生后20和30 d时逃避潜伏期延长,穿越平台次数减少,平台象限停留时间缩短(P＜0.05),海马NR2B mRNA及蛋白表达下调(P＜0.05);与E1组比较,E2组子鼠出生后20和30 d时海马NR2B mRNA及蛋白表达比较差异无统计学意义(P＞0.05).结论 孕早期安氟醚麻醉可降低大鼠子代的认知功能,其机制与抑制大鼠子代海马NR2B表达有关.     

氯化锂预先给药对异氟醚麻醉诱发老龄大鼠认知功能障碍及海马炎性反应的影响

目的 评价氯化锂(LiCl)预先给药对异氟醚麻醉诱发老龄大鼠认知功能障碍及海马炎性反应的影响.方法 老龄雄性SD大鼠80只,20月龄,体重350 ～400g,采用随机数字表法,将大鼠随机分为4组(n=20):对照组(C组)吸入30％O2-70％ N26h;异氟醚麻醉组(I组)吸入1.4％异氟醚6h,以30％O2-70％N2作为载气;LiCl+异氟醚麻醉组(L+I组)腹腔注射LiC1 100 mg/kg,1次/d,连续3d,第4d行异氟醚麻醉;LiCl组(L组)腹腔注射LiCl 100 mg/kg,1次/d,连续3d,第4d吸入30％ O2-70％ N26h.麻醉结束即刻行动脉血气分析,麻醉结束后24h取海马组织,采用Western blot法测定海马糖原合成酶激酶-3β(GSK-3β)和核因子κB第310赖氨酸乙酰化蛋白[acetyl-NF-κB (Lys310)]的表达,采用实时定量PCR和ELISA法分别检测海马TNF-α、IL1β和IL-6的mRNA表达及其含量;麻醉结束后第2d评估认知功能.结果 与C组比较,I组GSK-3β和acetyl-NF-κB (Lys310)表达上调,TNF-α、IL-1β及IL-6含量及其mRNA表达水平升高,逃避潜伏期延长,探索时间缩短(P＜0.05),L+I组和L组上述指标差异无统计学意义(P＞0.05);与I组比较,L+I组GSK-3β、acetyl-NF-κB (Lys310)表达下调,TNF-α、IL-1β、IL-6含量及其mRNA表达水平降低,逃避潜伏期缩短,探索时间延长(P＜0.05).结论 氯化锂预先给药可改善异氟醚麻醉诱发老龄大鼠认知功能障碍,其机制与抑制海马炎性反应有关.     

异氟醚麻醉对新生大鼠海马激活肌细胞增强因子2信号通路的影响

目的 探讨异氟醚麻醉对新生大鼠海马激活肌细胞增强因子2(MEF2)信号通路的影响.方法 取出生5 d的SD大鼠24只,雌雄不拘,体重10～13 g,采用随机数字表法,将大鼠随机分为2组(n=12):对照组(C组)和异氟醚组(I组).I组大鼠放置在密闭箱中,吸人1.5%异氟醚和纯氧,吸入时间6 h,C组不做任何处理.于异氟醚麻醉2、4、6 h和麻醉结束后24 h(T1-4)时(C组于相应时点)分别取3只大鼠,断头处死,取海马组织,采用RT-PCR法测定MEF2mRNA、synGAPⅠ mRNA和Arc mRNA及突触素Ⅰ mRNA的表达水平,采用Westrn blot法测定突触素Ⅰ蛋白的表达水平.结果 与C组比较,I组T1-3时海马MEF2mRNA、synGAP Ⅰ mRNA、Arc mRNA和突触素Ⅰ mRNA、T2-4时海马突触素Ⅰ蛋白表达水平均上调(P＜0.05).结论 吸入麻醉浓度的异氟醚可能通过激活新生大鼠海马MEF2信号通路从而影响发育期突触的形成.

Abstract：

Objective To investigate the effects of isoflurane anenthesia on myocyte enhancer factor 2(MEF2) signaling pathway in neonatal rat hippocampus. Methods Twenty-four 5-day-old SD rats of both sexes,weighing 10-13 g, were randomly divided into 2 groups ( n = 12 each): control group (group C) and isoflurane group (group I). In group I, 1.5% isoflurane in 100% O2 was inhaled for 6 h. Group C received no treatment.Three rata in each group were sacrificed at 2, 4, 6 h of isoflurane anenthesia and 24 h after isoflurane anenthesia (T1-4), and the hippocampi removed for determination of MEF2 mRNA, synGAP Ⅰ mRNA, Arc mRNA and synapsinⅠ mRNA expression (by PT-PCR) and synapsin Ⅰ protein expression (by Western blot).Results Compared with group C, the expression of MEF2 mRNA, synGAP Ⅰ mRNA, Arc mRNA and synapsin Ⅰ mRNA at T1-3 and synapsin Ⅰ protein at T2-4 was up-regulated in group I ( P ＜ 0.05). Conclusion Inhalation of anaesthetic concentration of isoflurane may affect synapse formation during the development of central nervous system by actirating hippocampal MEF2 signaling pathways in neonatal rats.     

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.     

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.     

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.     

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.