白藜芦醇对肝脏缺血再灌注损伤的保护作用

摘要：探讨白藜芦醇对肝脏缺血再灌注损伤的防护作用。将雄性SD大鼠随机分为空白对照组、缺血再灌注组（I/R组）、I/R加生理盐水处理组和I/R加白藜芦醇处理组。观察肝脏缺血40 min再灌注1，3，6，12h后血清谷丙转氨酶（ALT）、谷草转氨酶（AST）及肝组织丙二醛（MDA）含量的变化以及肝组织病理学改变。结果示肝脏I/R后血清ALT，AST及肝组织MDA含量均显著升高，肝脏缺血再灌注前用白藜芦醇15 mg/kg者，血清ALT，AST及肝组织MDA含量均明显降低，且肝组织病理学损害明显减轻。结果表明白藜芦醇对肝脏I/R损伤具有保护作用     

依托咪酯预处理对犬肝脏缺血/再灌注损伤时谷丙转氨酶、谷草转氨酶及肝组织内丙二醛、超氧化物歧化酶的影响

目的 观察依托咪酯预处理对犬肝脏缺血/再灌注(ischemia/reperfusion,I/R)血浆中谷丙转氨酶(alanine transaminase,ALT),谷草转氨酶(aspartate transaminase,AST)以及肝组织内丙二醛(malondialdehyde,MDA)、超氧化物歧化酶(superoxide dismutase,SOD)的影响,以及通过HE染色光镜下观察肝脏损伤情况. 方法 20只健康成年杂种犬按完全随机法随机分为4组(每组5只):假手术组(S组)、I/R组、小剂量依托咪酯预处理组(E1组)、大剂量依托咪酯预处理组(E2组).S组仅分离肝门不结扎,I/R组、E1组、E2组分别于肝缺血前30 min静注生理盐水、0.6 mg/kg依托咪酯和1.5 mg/kg依托咪酯,建立肝I/R模型,分别于缺血前即刻,缺血30 min,再灌注1、2h4个时间点取血清测ALT、AST值.术毕取肝组织测MDA含量、SOD活性,并HE染色,在光镜下行病理学观察.结果 I/R组、E1组、E2组各时间点血清ALT、AST活性均高于S组(p＜0.01),E1组、E2组各时间点血清ALT、AST活性均低于I/R组(P＜0.01),且E2组更显著[再灌注2 h:ALT:(2911±89) U/L(I/R组)、(863±95) U/L(E2组) ;AST:(2722±103) U/L(I/R组)、(1056±115) U/L(E2组)].与S组比较,I/R组、E1组、E2组肝组织MDA含量升高(P＜0.01),I/R组肝组织SOD活性降低,E1组、E2组肝组织SOD活性升高 ;与I/R组比较,E1组、E2组肝组织MDA含量降低、SOD活性升高(P＜0.01),且E2组更显著[MDA:(21.70±2.01) nmol· mg-1·prot-1(I/R组)、(12.69±1.02) nmol· mg-1 prot-1(E2组)、SOD:(191±12)nmol· mg-1· prot-1(I/R组)、(634±26) nmol·mg-1· prot-1(E2组)].E1组、E2组肝细胞病理学改变轻于I/R组,且E2组更明显. 结论 依托咪酯预处理对犬肝脏缺血/再灌注损伤(hepatic ischemia/reperfusion injury,HURl)具有明显保护作用,与其抑制脂质过氧化反应有关.且大剂量依托咪酯预处理组的保护作用较确实可靠.     

小剂量异丙酚联合缺血后处理对豚鼠心肌缺血再灌注损伤的影响

目的 探讨小剂量异丙酚联合缺血后处理对豚鼠心肌缺血再灌注损伤的影响.方法 24只白色雄性豚鼠,随机分为4组(n=6):缺血再灌注组(I/R组)、异丙酚组(P组)、缺血后处理组(IPC组)和异丙酚+缺血后处理组(P+IPC组).I/R组结扎左冠状动脉前降支30 min,再灌注90 min;P组自再灌注前5 min至再灌注15 min静脉输注异丙酚4 mg·kg-1·h-1;IPC组心肌缺血30 min,再灌注15 s,缺血15 s,反复4次,持续再灌注88 min;P+IPC组自再灌注前5 min至再灌注15 min静脉输注异丙酚4 mg·kg-1·h-1,余同IPC组.记录缺血前和再灌注90 min时左室收缩压(LVSP)、左室舒张末压(LVEDP)和左室压力变化速率(±dp/dtmax),计算左室发展压(LVDP=LVSP-LVEDP);再灌注90 min时取动脉血,测定血清肌酸激酶(CK)和乳酸脱氢酶(LDH)活性,取血后处死豚鼠,取心肌组织,测定心肌组织丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性.结果 与I/R组比较,P+IPC组再灌注90 min时LVDP和±dp/dtmax升高,LVEDP降低,血清CK、LDH活性及心肌组织MDA含量减少,心肌组织SOD活性增加(P＜0.05),P组和IPC组上述指标差异无统计学意义(P＞0.05).结论 再灌注前5 min至再灌注15 min静脉输注异丙酚4 mg·kg-1·h-1联合缺血后处理可通过抑制脂质过氧化反应,减轻豚鼠心肌缺血再灌注损伤.     

血红素加氧酶-1诱导对鼠肝缺血再灌注损伤的保护作用

目的研究血红素加氧酶-1(heme oxygenase-1,HO-1)在鼠肝缺血再灌注损伤肝组织中的表达及其作用。方法建立小鼠部分肝脏热缺血再灌注损伤模型,36只清洁级Balb/C小鼠随机分为3组: 假手术组(S组)、缺血/再灌注损伤组(I/R组)、HO-1诱导剂氯化高铁血红素(hemin)预处理组(HM组)。免疫组化半定量分析肝组织HO-1蛋白的表达,检测血清AST和ALT,肝组织丙二醛(MDA)含量及超氧化物歧化酶(SOD)活性,并观察肝组织的病理变化。结果与S组比较,I/R组HO-1蛋白表达显著增强,hemin预处理后,HO-1蛋白表达较I/R组增高(P<0．01)。I/R组AST,ALT活性和MDA的含量显著高于S组,而HM组均显著低于I/R组(P<0．01);I/R组SOD活性下降,而HM组显著高于I/R组(P<0．01)。HM组病理损伤程度明显轻于I/R组。结论 HO-1在鼠肝缺血再灌注损伤肝组织中表达上调,对肝脏具有保护效应。     

缺血预处理对大鼠缺血再灌注肝组织NF-κB表达、炎症及氧化应激反应的影响

目的：探讨缺血预处理（IP）减轻大鼠肝缺血再灌注（I/R）损伤的作用及机制。
　　方法：将15只雄性SD大鼠随机均分为假手术组、I/R组、IP+I/R组,采用Pringle法制作肝I/R模型（缺血30min+再灌注3h）,IP采用I/R前肝缺血10min+再灌注10min诱导。各组大鼠于再灌注3h后处死取材,行肝组织病理学、血请谷草转氨酶（AST）、谷丙转氨酶（ALT）检测,同时检测肝组织NF-κB蛋白的表达,以及炎性细胞因子IL-1β、TNF-α与氧化应激指标丙二醛（MDA）、髓过氧化物酶（MPO）水平。
　　结果：除假手术组外,I/R组与IP+I/R组大鼠肝组织均出现肝损伤是病理学改变,IP+I/R组的损伤程度明显轻于I/R组;与假手术组比较,I/R组与IP+I/R组大鼠血清AST、ALT水平明显升高,肝组织NF-κB蛋白表达、IL-1β与TNF-α水平、MDA与MPO浓度均明显升高（均P<0.05）,但IP+I/R组的各指标的升高幅度均明显小于I/R组（均P<0.05）。
　　结论：IP减轻大鼠肝I/R损伤的作用与抑制NF-κB活性,从而减轻炎症与氧化应激反应有关。     

前列腺素E1对大鼠肝脏缺血再灌注损伤的保护作用

摘要：目的:探讨肝脏缺血后前列腺素E1（PGE1）对再灌注损伤的保护作用及其可能机制。方法:建立大鼠70％的肝脏缺血再灌注模型。将24只健康雄性SD大鼠随机分为假手术（S）组、缺血再灌注（I/R）组及PGE1处理组，各组于缺血45 min再灌注1h后取静脉血，观察血清肝酶、超氧化物歧化酶（SOD）、丙二醛（MDA）、髓过氧化物酶（MPO）的含量变化，并行肝组织病理学检查。结果:与S组比较，I/R组与PGE1组血清ALT，AST，LDH显著升高，SOD活性明显降低，MDA和MPO含量均明显升高（P＜0.01）。PGE1组与I/R组相比，前者血清ALT，AST，LDH降低（P＜0.01），肝形态学异常变化明显减轻，血清SOD活性升高，MDA和MPO含量降低（P＜0.01）。结论:PGE1对大鼠肝脏I/R损伤有明显的保护作用；其作用机制部分可能是提高组织的抗氧化能力和减轻中性粒细胞的聚集。     

ATP敏感性钾通道在硫化氢减轻大鼠肝缺血再灌注损伤中的作用

目的 评价ATP敏感性钾(KATP)通道在硫化氢减轻大鼠肝缺血再灌注损伤中的作用.方法 健康雄性SD大鼠30只,体重220～250 g,采用阻断左叶和中叶肝脏血流的方法制备肝缺血再灌注损伤模型.采用随机数字表法,将大鼠随机分为5组(n=6):假手术组(S组)仅开腹分离肝蒂,不进行肝门阻断及再灌注;缺血再灌注组(I/R组)制备肝缺血再灌注模型;硫氢化钠组(NaHS组)于再灌注前5 min时腹腔注射NaHS 28 μmol/kg,余同I/R组;格列本脲组(G组)于NaHS给药前5 min时腹腔注射非选择性KATP通道阻断剂格列本脲6 mg/kg,余同NaHS组;5-羟基葵酸组(5-HD组)于NaHS给药前5 min时腹腔注射选择性KATP通道阻断剂5-HD 10 mg/kg,余同NaHS组.于再灌注6h时,采集下腔静脉血样,测定血清ALT和AST的活性;然后处死大鼠,取肝组织,测定TNF-α含量和MPO活性,并观察病理学结果.结果 与S组比较,I/R组、NaHS组、G组和5-HD组血清ALT和AST活性升高,I/R组、G组和5-HD组肝组织TNF-α含量和MPO活性升高,NaHS组肝组织TNF-α含量升高(P＜0.01);与I/R组比较,NaHS组血清ALT、AST活性和肝组织TNF-α含量、MPO活性降低(P＜0.01),病理学损伤减轻;与NaHS组比较,G组和5-HD组血清ALT、AST活性和肝组织TNF-α含量、MPO活性升高(P＜0.01).结论 KATP通道的开放参与了硫化氢减轻大鼠肝缺血再灌注损伤.     

异丙酚对肢体缺血/再灌注大鼠肺损伤的影响

目的观察异丙酚对肢体缺血/再灌注大鼠肺损伤的影响。方法健康Wistar大鼠36只,体重300-350g,随机分为3组:假手术组(Sham组,n=12),只进行手术操作不做其他处理;肢体缺血/再灌注组(I/R组,n=12),双后肢缺血4h、再灌注6h;异丙酚组(P组,n=12)于开放前10min静脉注射异丙酚5mg·kg-1随后以10mg·kg-1·h-1的速率输注,I/R、Sham组输注等量生理盐水。实验结束,颈动脉放血处死大鼠,测定肺组织丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性及肺组织含水率,光镜和电镜下观察肺组织形态学改变及肺组织诱导型一氧化氮合酶(iNOS)、细胞间黏附分子-1(ICAM-1)的表达。结果肺含水率:I/R、P组均较Sham组增加,但P组低于I/R组(P<0.05或0.01);肺组织MDA含量:I/R组较Sham组升高,P组低于I/R组(P<0.01),且与Sham组相比差异无统计学意义(P>0.05);肺组织SOD活性:I/R、P组均较Sham组降低,但P组高于I/R组(P<0.01或0.05)。光镜观察,I/R组肺间隔增厚,间质中有大量中性粒细胞浸润,局部肺出现不张、肺泡水肿;电镜观察,I/R组部分肺泡上皮细胞缺损,Ⅰ型上皮细胞肿胀,Ⅱ型上皮细胞微绒毛稀疏、板层小体排空,P组肺组织病变明显改善。P组肺组织iNOS、ICAM-1表达较I/R组明显减少。结论异丙酚对肢体缺血,再灌注大鼠肺损伤具有一定程度的保护作用,其机制可能与减轻肢体缺血/再灌注后肺组织的氧化损伤及下调损伤肺组织iNOS、ICAM-1表达有关。     

雌激素对大鼠肝切除肝缺血再灌注损伤中核因子-κB/IκB传导通路的影响及保护作用

目的 观察雌激素对大鼠肝切除肝缺血再灌注损伤中核因子-κB(NF-κB)/抑制蛋白(IκB)传导通路影响.方法 制作肝切除肝缺血再灌注损伤动物模型,雄性SD大鼠随机分为3组:假手术组(Sham组);肝切除肝缺血再灌注组(I/R组);肝切除肝缺血再灌注+雌激素组(I/R+ E2 组).分别在缺血再灌注后1、3、6h光镜下观察肝组织病理学改变,检测血清天冬氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)的水平和肝组织丙二醛(MDA)的含量及超氧化物岐化酶(SOD)的活性,免疫组织化学法测定肝组织NF-κB的表达,Western blot检测NF-κB抑制蛋白(IκB-α)和细胞间黏附分子-1(ICAM-1)表达,流式细胞仪检测细胞凋亡率.结果 再灌注后I/R组在各时相血清ALT、AST均显著高于I/R +E2组,并于6h达到峰值(P＜0.05).与I/R+E2组和Sham比较,I/R组肝细胞凋亡率显著升高(P＜0.01);肝组织中IκB-α表达降低,而NF-κB表达增高(P＜0.05);ICAM-1 和MDA的结果变化和NF-κB表达水平变化类似,SOD呈相反变化.在光镜下观察,I/R组肝小叶结构紊乱,肝窦淤血,肝细胞水肿变性,肝细胞片状坏死,在Sham组和I/R +E2组上述病理学变化明显改善.结论 雌激素对肝切除肝脏缺血再灌注损伤有显著保护作用,其作用机制可能与雌激素影响NF-κB/IκB传导通路、减轻脂质过氧化反应、减少炎症介质释放及抑制细胞凋亡有关.     

异丙酚后处理联合缺血后处理对大鼠肝脏缺血再灌注损伤的影响

目的 探讨异丙酚后处理联合缺血后处理对大鼠肝脏缺血再灌注损伤的影响.方法 健康雄性sD大鼠30只,体重200～250 g,随机分为5组(n=6),假手术组(Ⅰ组)仅开腹;缺血再灌注组(11组)肝脏缺血1 h再灌注4 h;缺血后处理组(Ⅲ组)肝脏缺血1 h后,再灌注10 8,缺血10 8,重复6次进行缺血后处理;异丙酚后处理组(Ⅳ组)肝脏缺血1 h后经尾静脉注射异丙酚10 mg/kg,随后静脉输注异丙酚40 mg·kg~(-1)·h~(-1) h;异丙酚后处理+缺血后处理组(V组)肝脏缺血1 h后进行异丙酚后处理及缺血后处理.于再灌注4 h时测定血清ALT活性、肝组织MDA含量、SOD活性、Bcl-2及Bax的蛋白表达水平,电镜下观察肝细胞超微结构.结果 与Ⅰ组比较,Ⅱ组～Ⅴ组血清ALT活性及肝组织MDA含量升高,肝组织Bcl-2蛋白表达上调,Ⅲ组-Ⅴ组肝组织SOD活性升高,Ⅱ组、Ⅲ组及Ⅴ组肝组织Bax蛋白表达上调(P<0.05或0.01);与Ⅱ组比较,Ⅲ组-Ⅴ组血清ALT活性及肝组织MDA含量降低,肝组织SOD活性升高,Bcl-2蛋白表达上调,Bax蛋白表达下调(P<0.05或0.01);与Ⅲ组比较,Ⅳ组血清ALT活性及肝组织MDA含量降低(P<0.05或0.01).Ⅲ组-Ⅴ组肝组织病理学损伤较Ⅱ组明显减轻.结论 异丙酚后处理联合缺血后处理可减轻大鼠肝脏缺血再灌注损伤,与异丙酚后处理单独应用时效果相同,其机制可能与抑制肝组织脂质过氧化反应及细胞凋亡有关.     

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.     

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.     

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.     

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.