瑞芬太尼预先给药对兔心肌缺血再灌注损伤的影响

目的 评价瑞芬太尼预先给药对兔心肌缺血再灌注损伤的影响.方法 健康家兔30只,月龄12～18个月,体重2.5～3.5kg,随机分为3组(n=10):缺血再灌注组(IR组)、低剂量瑞芬太尼预先给药组(R1组)和高剂量瑞芬太尼预先给药组(R2组).3组均采用结扎左冠状动脉前降支30 min开放的方法制备心肌缺血再灌注模型,R1组和R2组分别静脉输注瑞芬太尼1.65、3.30μg·kg-1·min-130 min时进行缺血,IR组给予等容量生理盐水.于给药前(基础状态)、给药结束时、缺血30 min、再灌注6 h时采集静脉血样,测定血清心肌肌钙蛋白I(cTnI)和MB型肌酸激酶同工酶(CK-MB)的浓度.再灌注结束时处死动物,取心肌组织,光镜和电镜下观察病理学结果.结果 与IR组比较,R1组和R2组血清cTnI和CK-MB浓度降低(P＜0.01);与R1组比较,R2组血清cTnI浓度降低(P＜0.01).R1组和R2组心肌病理学损伤程度均轻于IR组,且R2组心肌病理学损伤程度轻于R1组.结论 瑞芬太尼预先给药可减轻兔心肌缺血再灌注损伤,且与剂量有关.     

瑞芬太尼后处理对脑缺血再灌注大鼠海马神经元凋亡的影响

目的 探讨瑞芬太尼后处理对脑缺血再灌注大鼠海马神经元凋亡的影响.方法 健康成年雄性SD大鼠24只,体重250～300 g,随机分为4组(n=6):假手术组(S组)、缺血再灌注组(IR组)、瑞芬太尼0.6μg·kg-1·min-1组(R1组)和瑞芬太尼1.8μg·kg-1·min-1组(R2组).采用夹闭双侧颈总动脉联合低血压法制备大鼠全脑缺血再灌注模型.R1组和R2组分别于再灌注前5 min泵注瑞芬太尼0.6、1.8μg·kg-1·min-1,注射时间5 min.于再灌注第3天采用Morris水迷宫实验及跳台实验测定大鼠认知功能.水迷宫实验结束后,处死大鼠取脑分离海马,采用免疫组化法检测海马CA1区caspase-3蛋白的表达,TUNEL法检测神经元凋亡情况.结果 与S组相比,IR组、R1组和R2组大鼠认知功能减退,海马CA1区神经元凋亡数目升高,IR组caspase-3表达上调(P＜0.05);与IR组相比,R1组和R2组大鼠认知功能提高,海马CA1区caspase-3表达水平和凋亡神经元数目降低(P＜0.05).结论 瑞芬太尼后处理可通过下调caspase-3表达,抑制海马神经元凋亡,从而改善脑缺血再灌注大鼠的认知功能.     

瑞芬太尼后处理对犬心肺转流后心肌缺血-再灌注损伤的影响

目的研究瑞芬太尼后处理对心肺转流(CPB)犬缺血-再灌注心肌的保护作用及机制。方法 18只成年雄性犬,随机均分为缺血-再灌注组(C组)、缺血后处理组(I组)和瑞芬太尼后处理组(R组)。建立犬CPB模型,阻断升主动脉血流60min。主动脉阻断55min时自主动脉根部进行温血再灌注;I组在开放主动脉之前给予开放30s/再阻断30s三个循环;R组随温血输注瑞芬太尼4μg·kg-1·min-1,持续5min。测定CPB前5min(T0)、开放升主动脉5min(T1)、停CPB30min(T2)和120min(T3)时血浆肌钙蛋白I(cTnI)、丙二醛(MDA)浓度和超氧化物歧化酶(SOD)活性,停CPB120min后测定心肌含水率并观察心肌组织超微结构改变。结果与T0时比较,T1～T3时三组血浆cTnI和MDA浓度均明显升高(P<0.01),而SOD活性明显降低(P<0.01)。T1～T3时I组和R组cTnI和MDA浓度均低于C组(P<0.01),SOD活性高于C组(P<0.01)。I组和R组心肌含水率和超微结构改变均低于或轻于C组(P<0.01),I组和R组各指标差异无统计学意义。结论瑞芬太尼后处理减轻犬CPB后心肌缺血-再灌注损伤,其机制可能与减少活性氧生成并增加SOD活性进而减轻氧化应激有关。     

大鼠急性肝缺血-再灌注时心肌细胞氧化损伤及瑞芬太尼的干预作用

目的 观察大鼠急性肝缺血-再灌注时心肌细胞氧化损伤以及瑞芬太尼预处理对氧化损伤的干预作用.方法 建立大鼠肝缺血-再灌注损伤模型.将72只Wistar大鼠随机分为瑞芬太尼预处理组(R组,n=24)、缺血-再灌注组(IR组,n=24)、假手术组(Sham组,n=24).于再灌注30min、1、2、3 h处死大鼠.R组缺血前以1μg·kg-1·min-1微泵输注瑞芬太尼30 min进行预处理.分别检测各组大鼠心肌组织丙二醛(MDA)含量、超氧化物歧化酶(SOD)活力及谷胱甘肽过氧化氧酶(GSH-Px)活力变化.结果 与Sham组比较,R组和IR组再灌注1、2、3 h时心肌组织MDA含量明显升高,SOD、GSH-Px活力明显降低(P<0.05).与IR组比较,R组再灌注30 min、1 h时心肌组织MDA含量降低,SOD、GSH-Px的表达增高(P<0.05).结论 大鼠急性肝缺血-再灌注可造成心肌细胞氧化损伤,而瑞芬太尼预处理可起到一定的保护作用.     

瑞芬太尼预处理对大鼠肝脏缺血-再灌注损伤中NF-κB和ICAM-1表达的影响

目的观察瑞芬太尼预处理对大鼠肝脏缺血-再灌注损伤中核因子-κB(NF-κB)和细胞间粘附因子-1(ICAM-1)表达的影响。方法用SD大鼠制作肝脏缺血-再灌注模型,随机分为假手术组(S组)、缺血-再灌注组(IR组)和瑞芬太尼预处理组(R组)。S组经股静脉给予与R组相同的速率及容积的生理盐水输注15min,停药10min,然后行剖腹和关腹,但不进行缺血-再灌注;IR组同S组一样给予生理盐水的输注,然后进行缺血45min和再灌注2h;R组股静脉用微量泵给予瑞芬太尼1μg·kg-1·min-1预处理,持续给药15min,停药10min,然后进行缺血-再灌注。光镜下观察三组组织学病理改变,检测血清中丙氨酸转氨酶(ALT)和天冬氨酸转氨酶(AST)水平,Western blotting检测NF-κB和ICAM-1相对灰度值。结果光镜显示R组的损伤程度小于IR组。与S组比较,IR组和R组血清ALT、AST水平、肝组织NF-κB和ICAM-1相对灰度值明显升高(P0.05);与IR组比较,R组血清中ALT、AST水平、肝组织NF-κB和ICAM-1相对灰度值明显降低(P0.05)。结论瑞芬太尼预处理能够减轻肝脏缺血-再灌注时损伤的程度,可能与抑制NF-κB的活性,从而减少ICAM-1的表达有关。     

瑞芬太尼后处理对CPB心内直视手术患者心肌缺血再灌注损伤的影响

目的 评价瑞芬太尼后处理对CPB心内直视手术患者心肌缺血再灌注损伤的影响.方法 择期行室间隔缺损修补术和/或房间隔缺损修补术的先天性心脏病患者30例,年龄18～45岁,ASA分级Ⅱ或Ⅲ级,心功能分级Ⅰ或Ⅱ级,随机分为2组(n=15).在主动脉开放前8 min瑞芬太尼组(R组)从主动脉根部以4μg·kg-1·min-1的速率输注瑞芬太尼5 min,对照组(C组)给予等容量生理盐水.于麻醉诱导前(基础状态)、主动脉开放后4、8、24、48 h时采集右颈内静脉血样,检测心肌肌钙蛋白I(cTnI)、丙二醛(MDA)的浓度及MB型肌酸激酶同工酶(CK-MB)、超氧化物歧化酶(SOD)的活性.结果 与C组比较,R组主动脉开放后4、8 h时cTnI、MDA浓度及CK-MB活性降低,SOD活性升高,主动脉开放后24 h时MDA浓度降低(P＜0.05).结论 瑞芬太尼后处理可减轻CPB心内直视手术患者心肌缺血再灌注损伤,其机制与抑制脂质过氧化反应有关.     

瑞芬太尼后处理及其联合异丙酚后处理对大鼠肝脏缺血再灌注损伤的影响

目的 评价瑞芬太尼后处理及其联合异丙酚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220 ～ 280 g,采用随机数字表法,将其随机分为5组(n=6):假手术组(Ⅰ组)、缺血再灌注组(Ⅱ组)、异丙酚后处理组(Ⅲ组)、瑞芬太尼后处理组(Ⅳ组)和异丙酚联合瑞芬太尼后处理组(Ⅴ组).Ⅱ组～Ⅴ组采用夹闭门静脉和肝动脉30 min的方法制备肝脏缺血再灌注损伤模型,Ⅰ组仅开腹.Ⅲ组、Ⅳ组和Ⅴ组再灌注即刻分别静脉输注异丙酚30 mg· kg-1·h-1、瑞芬太尼1μg·kg -1·min -1和异丙酚30 ng·kg-1·h-1+瑞芬太尼1μg·kg-1·min-1 1 h,Ⅱ组给予等容量生理盐水.于再灌注1h时采集静脉血样,测定血清AST、ALT活性、IL-8、IL-10的浓度,然后处死大鼠,取肝组织,测定肝细胞c-fos和c-jun表达,电镜下观察肝组织病理学结果.结果 与Ⅰ组比较,Ⅱ组～Ⅴ组血清AST、ALT活性及IL-8、IL-10的浓度升高,肝细胞c-fos和c-jun表达上调(P＜0.05或0.01);与Ⅱ组比较,Ⅲ组～Ⅴ组血清AST、ALT活性及IL-8浓度降低,IL-10浓度升高,肝细胞c-fos和c-jun表达下调(P ＜0.05或0.01);与Ⅲ组及Ⅳ组比较,Ⅴ组上述指标差异无统计学意义(P＞0.05).Ⅲ组～Ⅴ组肝组织病理学损伤程度明显轻于Ⅱ组.结论 瑞芬太尼后处理可减轻大鼠肝脏缺血再灌注损伤,联合异丙酚后处理时其效应与单独一种方法的效应相似,其机制与抑制炎性反应和肝细胞凋亡有关.     

瑞芬太尼对大鼠心肌缺血再灌注时血清TNF-α、IL-1β和IL-6浓度的影响

目的 探讨瑞芬太尼对大鼠心肌缺血再灌注时血清肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)及白细胞介素-6(IL-6)浓度的影响.方法 雄性SD大鼠32只,体重200～250 g,随机分为假手术组(S组)、缺血再灌注组(I/R组)、缺血预处理组(IP组)和瑞芬太尼组(R组),每组8只.I/R组阻断冠状动脉左前降支(LAD)30 min,开放120 min;IP组阻断LAD 5 min,开放10 min,阻断30 min,开放120 min;R组静脉输注瑞芬太尼0.5 μg·kg-1·min-1 20 min,阻断LAD 30 min,开放120 min,此期间静脉输注100 μg/L瑞芬太尼,速率0.5 μg·kg-1·min-1.分别于再灌注120 min取颈内静脉血样,并取左心室心肌组织.ELISA法测定血清TNF-α、IL-Iβ及IL-6浓度,电镜下观察心肌细胞超微结构.结果 与S组比较,其余3组血清TNF-α、IL-1β和IL-6浓度升高(P＜0.01);与I/R组比较,IP组和R组血清TNF-α、IL-1β和IL-6浓度均降低(P＜0.01);与IP组比较,R组血清TNF-α和IL-1β浓度降低(P＜0.05).R组和IP组心肌细胞损伤程度轻于I/R组.结论 瑞芬太尼可通过降低血清TNF-α、IL-1β和IL-6浓度减轻大鼠心肌缺血再灌注损伤.     

瑞芬太尼对兔心肌缺血再灌注时NF-κB活性的影响

目的 探讨瑞芬太尼对兔心肌缺血再灌注时NF-κB活性的影响.方法 健康成年新西兰大白兔50只,月龄2～3月,体重2.0～2.5 kg,随机分为5组(n=10):假手术组(S组)左冠状动脉前降支只穿线不结扎;缺血再灌注组(IR组)冠状动脉前降支穿线结扎30 min,再灌注120 min;S组和IR组在缺血前10 min时颈外静脉输注生理盐水5 ml·kg-1·h-1至再灌注120 min;低、中、高剂量瑞芬太尼组(L组、M组、H组)缺血前10 min时颈外静脉输注瑞芬太尼1、5、10μg·kg-1·min-1至再灌注120 min,余处理同IR组.再灌注120 min时处死动物取心脏,采用Western blot法测定心肌细胞核NF-κB的表达水平,以反映其活性,观察心肌组织病理学结果.结果 与S组比较,其余各组NF-κB活性升高(P＜0.05);与IR组比较,L组、M组和H组NF-κB活性降低(P＜0.05),L组、M组和H组NF-κ:B活性依次降低(P＜0.05);病理学结果显示:L组、M组和H组心肌缺血再灌注损伤程度较IR组减轻,且随剂量增加,损伤逐渐减轻.结论 静脉输注瑞芬太尼可通过降低NF-κB活性减轻兔心肌缺血再灌注损伤,其效应呈剂量依赖性.     

瑞芬太尼预处理对患儿体外循环诱导心肌缺血再灌注损伤的影响

目的观察瑞芬太尼预处理对先天性心脏病患儿体外循环诱导心肌缺血再灌注损伤的影响。方法先天性心脏病室间隔缺损患儿60例,年龄2-14岁,ASA分级Ⅰ级或Ⅱ级,心功能分级Ⅰ级或Ⅱ级,随机分为4组(n=15),对照组(C组)持续静脉输注瑞芬太尼0．2-0.5μg·kg-1·min-1;R1组、R2组、R3组主动脉阻断前分别以1、2、4μg·kg-1·min-1的速率静脉输注瑞芬太尼5 min,间隔5 min后重复输注瑞芬太尼,每组重复3次。于麻醉诱导前(T1)、主动脉阻断前即刻(T2)、主动脉开放即刻(T3)、主动脉开放后2 h(T4)、24 h(T5)、48 h(T6)采取血标本,检测心肌肌钙蛋白I(cTnI)的浓度和磷酸肌酸激酶同工酶(CK-MB)的活性。记录主动脉阻断前各时点的HR和MAP及主动脉开放后心脏复跳情况。结果与C组比较,R1组、R2组和R3组在主动脉阻断前各时点HR及MAP差异无统计学意义,R1组、R2组和R3组在T1、T2时cTnI及CK-MB差异无统计学意义(P>0．05),R3组在T3时cTnI降低,R2组、R3组在T3时CK-MB降低,R1组、R2组和R3组在T4、T5、T6时cTnI及CK-MB降低(P<0．05或0．01);与R1组比较,R3组在T4时cTnI降低(P<0．05)。结论瑞芬太尼预处理可减轻先天性心脏病患儿体外循环诱导的心肌缺血再灌注损伤。     

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 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.     

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.     

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.