不同年龄患儿罗库溴铵药效学的比较

目的 比较新生儿、婴儿、幼儿和儿童罗库溴铵的药效学.方法 择期全麻手术患儿160例,ASAⅠ或Ⅱ级,根据年龄分为4组(n=40):新生儿组、婴儿组、幼儿组及儿童组.各组随机选取患儿20例,采用4次累积给药法静脉注射罗库溴铵,初始剂量:新生儿组40 μg/kg,婴儿组80 μg/kg,幼儿组及儿童组均为120 μg/kg,后3次均追加罗库溴铵40μg/kg.每次给药后.观察TOF反应.当T1连续3次稳定不变时,给予下一次剂量.采用概率单位法计算T1抑制50%、90%、95%的用药量(ED50、ED90、ED95).各组随机选取20例患儿,静脉注射2倍ED95剂量的罗库溴铵,记录肌松起效时间、高峰时间、临床肌松时间、体内作用时间和恢复指数.结果 与新生儿组比较,幼儿组和儿童组罗库溴铵ED50、ED90和ED95均升高(P<0.01),婴儿组上述指标差异无统计学意义(P>0.05).婴儿组、幼儿组和儿童组罗库溴铵起效时间、临床肌松时间和体内作用时间缩短,恢复指数降低(P<0.01);与幼儿组比较.儿童组罗库溴铵ED50、ED90和ED95升高(P<0.01).结论 不同年龄患儿对罗库溴铵的量效关系和时效关系存在明显的差别,新生儿对罗库溴铵的敏感性最强.     

癫痫患者罗库溴铵95％有效量的测定

目的 通过测定癫痫患者罗库溴铵95％有效量(95％ effective dose,ED95),为癫痫患者合理应用罗库溴铵提供依据. 方法 选取择期行癫痫病灶切除术患者40例,ASA分级Ⅰ、Ⅱ级.根据罗库溴铵不同剂量按随机数字表法分为4组(每组10例):120 μg/kg组、180 μg/kg组、240 μg/kg组和300 μg/kg组.采用单次剂量注射法测定患者ED95,记录拇指内收肌“四个成串刺激(train of four stimulation,TOF)”第1个肌颤搐反应(T1)最大抑制的百分比及药物的起效时间,将最大抑制百分比进行概率单位转换,罗库溴铵的首次剂量做对数转换,用直线回归方法建立维库溴铵的剂量-反应曲线,计算出癫痫患者的罗库溴铵ED95值. 结果 各组间一般情况比较,差异无统计学意义(P＞0.05);不同剂量组起效时间比较,差异无统计学意义(P＞0.05),T1最大抑制程度随剂量增加而增加(P＜0.05),但240 μg/kg组和300 μg/kg组间差异无统计学意义(P＞0.05);癫痫患者罗库溴铵ED95值为445.3 μg/kg,高于目前正常人群广泛应用的ED95值300 μg/kg(P＜0.05). 结论 癫痫患者罗库溴铵的ED95值高于正常人群,在该类患者中应增加罗库溴铵的剂量约50％以取得与正常人群相同的肌松水平.     

肥胖对女性患者罗库溴铵剂量-效应曲线的影响

目的观察肥胖对女性患者罗库溴铵剂量-效应曲线的影响,并计算肥胖女性患者罗库溴铵的95%有效剂量(ED95)。方法选择择期行全身麻醉女性患者80例,年龄18~45岁,ASAⅠ或Ⅱ级,手术时间1.5h。根据BMI 20~25kg/m2和30~35kg/m2分为N组与B组,每组40例。两组患者根据随机数字表法各分为0.075、0.1、0.15、0.3 mg/kg四个剂量组,分别为N1~N4组和B1~B4组。麻醉诱导同时开启注射泵,待患者意识消失后,校对肌松监护仪,启动TOF模式,N1~N4组和B1~B4组分别给予罗库溴铵单次剂量0.075、0.1、0.15、0.3mg/kg。记录各组患者给予罗库溴铵的首次剂量、第一个肌颤搐反应(T1)的最大抑制程度和肌松药起效时间。采用直线回归法建立罗库溴铵量效关系回归方程,计算N组和B组患者的ED50和ED95及其95%CI。结果 N组和B组的量效关系回归方程分别为Y1=3.464X1-2.230和Y2=3.843X2-2.750。B组ED50、ED75、ED90、和ED95分别为0.103、0.145、0.201和0.251 mg/kg明显小于N组0.122、0.176、0.254和0.324mg/kg(P0.05)。N组与B组T1最大抑制程度均随药量的增加而增大(P0.05)。结论肥胖影响年轻女性患者罗库溴铵的量效曲线,使其对罗库溴铵的敏感性增强,肥胖女性罗库溴铵ED95为0.251mg/kg。     

罗库溴铵用于婴儿骨科手术的临床效果

目的观察罗库溴铵用于婴儿骨科手术的药效学和临床效果。方法 80例择期全麻骨科手术患儿,年龄1~12月。研究分为两部分:(1)量效关系测定:40例婴儿随机分为L1、L2、L3、L4组,建立罗库溴铵量-效关系曲线,计算ED50和ED95。(2)肌松时效观察:其余40例随机给予1倍ED95(L5组)、1.5倍ED95(L6组)、2倍ED95(L7组)、3倍ED95(L8组)罗库溴铵,记录插管条件、起效时间、恢复时间、恢复指数。结果婴儿罗库溴铵ED50为175.14μg/kg,95%可信区间(CI)69.96~533.62μg/kg;ED95为232.31μg/kg,95%CI 90.42~728.62μg/kg。随着罗库溴铵剂量的增大,L6组、L7组、L8组起效时间明显短于L5组(P0.05或P0.01),肌颤搐恢复时间明显长于L5组(P0.05);L7组和L8组恢复指数明显慢于L5组和L6组(P0.05或P0.01)。结论 1.5倍ED95即350μg/kg罗库溴铵即能够提供婴儿良好的气管插管条件,适用于手术时间短而又需要全麻插管的手术。     

罗库溴铵用于老年人的有效剂量探讨

目的　用单次剂量法评估罗库溴铵在老年人和中年人剂量反应的差异 ,并探讨其可能的机制。方法　择期全麻手术患者 80例 ,分成中青年组 (30～ 4 5岁 )和老年组 (>6 5岁 ) ,每组 4 0例。按罗库溴铵用量将老年组再分成 10 0、15 0、2 0 0、2 5 0和 2 75 μg/kg五个亚组 ,中青年组分为 10 0、15 0、2 0 0、2 5 0和 30 0 μg/kg五个亚组 ,每亚组 8例。丙泊酚和芬太尼诱导及手控气囊面罩通气下 ,用加速度仪以连续 4次刺激方式刺激尺神经 ,获取静脉注射罗库溴铵后T1最大抑制 (Tmax)程度和时间。结果　老年组罗库溴铵的ED50 、ED90 和ED95分别为 (115 0 8± 35 10 ) μg/kg、(2 4 7 4 4± 32 95 )μg/kg和 (2 6 3 10± 34 15 ) μg/kg ,中青年组分别为 (15 0 5 0± 2 9 2 8) μg/kg、(2 74 0 4± 30 6 3) μg/kg和 (2 89 4 9± 31 70 ) μg/kg。老年组的ED50 、ED90 及ED95分别是中青年组的 76 %、90 3%和 91 2 %(P <0 0 1)。老年组的血清钾、血浆总蛋白和白蛋白浓度低于中青年组 (P <0 0 5 )。结论　罗库溴铵在正常体重老年人的作用强度大于中青年。年龄组间罗库溴铵作用强度的差异可能与电解质和血浆蛋白水平的差异有关     

全麻患者在异丙酚不同靶控浓度下罗库溴铵对脑电双频指数的影响

目的：探讨异丙酚在不同靶控浓度下．罗库溴铵对脑电双频指数（Bispectral index．BIS）监测麻醉深度的影响。。方法：ASA I级或II级择期手术患者60例．随机分为4组（n=15）：实验组（R2和R3）和对照组（C2和C3）。设定异丙酚初始效应室浓度（effect-site concentration．Ce）为4．0Hg／mL。当患者镇静警觉评分（0AA／S评分）≤1时置入喉罩。机械通气,调节异丙酚靶控浓度．使Ce维持在2．0μg／mL或3．0μg／mL．达到靶浓度后稳定20min．实验组（R2和R3）静脉注射2倍ED95剂量的罗库溴铵0．6mg／kg,对照组[C2和C3）注射生理盐水（5ml）。记录异丙酚诱导前即刻（T1）,静脉注射罗库溴铵或生理盐水即刻（T2）、TOF消失为0对（T3）、TOF的第一个肌颤搐恢复到5％时（T4）BIS,HR．MAP值。结果：四组患者性别．年龄、体重之间差异无显著性罄异（P〉0．05）;对照组T1～T4各时点BIS值比较差异无统计学意义（P〉0．05）;与b对比较．R2组T3和T4时BIS降低（P〈0.05）,但R3组、C2绍和C3组变化差异无统计学意义（P〉0．05）。实验组与相同异丙酚效应室浓度对照组比较．R2组．C2组与R3组、C3组在静脉注射罗库溴铵或生理盐水前后变化差异无统计学意义（P〉0．05）。结论：罗库澳铵对BIS值的影响与镇静深度有关。异丙酚靶控浓度维持在2．0μg／mL较浅的镇静状态下,静脉注射2倍ED95剂量的罗库澳铵可引起BIS数值的下降。但在3．0μg／mL较深的镇静状态下．2倍ED85剂量的罗库溴铵对BIS值无影响。     

丙泊酚对罗库溴铵有效剂量的影响

目的 比较丙泊酚不同输注时间对罗库溴铵有效剂量的影响.方法 中青年女性全麻手术患者24例,以血浆靶浓度4 μg/ml输注丙泊酚和静注雷米芬太尼1/μg/kg麻醉诱导,气管内插管.输注丙泊酚和雷米芬太尼维持脑电双频指数40～50.监测拇内收肌颤搐反应.持续输注丙泊酚5 min(Ⅰ组)或20 min(Ⅱ组)后,给予首剂量罗席溴铵150 μg/kg.当TOF的T1下降并稳定在同一高度时,静注罗库溴铵50 μg/kg,直到T1抑制程度超过90%.记录每次静脉注射罗库溴铵后T1稳定值、间隔时间和皮温测定值,观察有无不良反应.结果 Ⅰ组罗席溴铵ED90和ED95分别为(261.6士53.8)μg/kg和(321.9±73.9)μg/kg,略高于Ⅱ组的(235.3±46.9)μg/kg和(297.7士53.5)μg/kg.两组罗库溴铵量效关系曲线的斜率和截距差异均无统计学意义.结论 中青年女性患者输注丙泊酚对罗库溴铵有效剂量无明显影响.     

罗库溴铵用于小儿的量效关系和肌松时效

目的　研究罗库溴铵用于小儿的量效关系和作用时效。方法　选择小儿与成人各40 例,用单次给药技术建立量效关系曲线,计算ED50、ED90和ED95;选择小儿与成人各10例,静脉注射 罗库溴铵600μg/kg后,记录起效时间、作用时间和恢复时间。结果　小儿与成人罗库溴铵的ED50 分别为199.6μg/kg和177.0μg/kg,ED90分别为297.8μg/kg和264.2μg/kg,ED95分别为 333.6μg/kg和295.9μg/kg;小儿与成人的起效时间分别为(84.4±15.4)s和(111.0±17.7)s,临床 肌松时间分别为(22.2±5.3)min和(28.8±6.2)min,恢复指数分别为(9.0±3.0)min和(12.5± 4.1)min,组间比较有显著性差异(P<0.05,P<0.01)。结论　小儿罗库溴铵的ED50、ED90和ED95 均大于成人,且起效快、作用时间短、恢复快。     

紫绀及非紫绀型先天性心脏病患儿罗库溴铵药效学的比较

目的 比较紫绀及非紫绀型先天性心脏病(先心病)患儿罗库溴铵的药效学。方法 第一部分:选择非紫绀、轻度紫绀及重度紫绀型先心病患儿各12例,分别为非紫绀组、轻度紫绀组、重度紫绀组,测定0.6 mg／kg罗库溴铵的起效时间、作用时间及恢复指数。第二部分:40例先心病患儿,选择非紫绀、紫绀型先心病患儿各20例,分别为非紫绀组和紫绀组,每组患儿随机分为120、180、240、300μg／kg四个剂量组,用直线回归法建立罗库溴铵的量效曲线,计算罗库溴铵的ED50、ED90,及ED95。结果 第一部分:重度紫绀组起效时间较非紫绀组明显延长(P<0.05),三组间作用时间及恢复指数无差异。第二部分:紫绀组罗库溴铵的量效关系曲线较非紫绀组右移,紫绀组罗库溴铵ED50、ED90及ED95均较非紫绀组高(P<0.05)。结论 重度紫绀型先心病患儿罗库溴铵的起效时间延长,且对罗库溴铵的敏感性降低。     

罗库溴铵和阿曲库铵联合应用的肌松效应分析

目的探讨罗库溴铵和阿曲库铵联合应用时的肌松效应。方法择期全麻手术女性成年患者147例,丙泊酚和舒芬太尼静脉诱导,输注丙泊酚维持麻醉。面罩辅助或控制呼吸,用加速度仪以连续4次刺激(TOF)方式透皮刺激腕部尺神经,获取肌松药作用起效时间和T1最大抑制程度(Tmax)。按观测项目将患者均分成四组。结果阿曲溴铵ED95为(220.8±3.6)μg/kg,罗库溴铵ED95为(286.3±3.1)μg/kg。0.5×ED95的罗库溴铵与阿曲库铵联合使用,肌松效应达到T1抑制93%~97%时,阿曲库铵的剂量为63.6μg/kg。罗库溴铵0.5×ED95与阿曲库铵63.6μg/kg联合使用,Tmax为(95.3±0.9)%,变异系数1.0%。Ⅳ组中三个亚组的Tmax基本相同,合用组作用起效时间比阿曲库铵组快(P<0.01)。给予肌松药前和注药后5min内,MAP和HR的波动幅度均小于5%。结论罗库溴铵与阿曲库铵合用呈协同作用。当罗库溴铵剂量为0.5×ED95时,为获得T1抑制95%的肌松效应,阿曲库铵的合理用量为63.6μg/kg,比阿曲库铵的ED95减少71.2%。     

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.     

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.     

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.