小剂量氯胺酮对脑电熵指数和脑电双频指数的影响

目的比较小剂量氯胺酮对脑电熵指数(RE、SE)和脑电双频指数(BIS)的影响。方法22例ASAⅠ或Ⅱ级择期行腹腔镜子宫切除术及卵巢囊肿切除术患者,随机均分为氯胺酮组(K组)和生理盐水组(S组)。麻醉诱导:丙泊酚1～2mg/kg、雷米芬太尼1～1.5μg/kg和维库溴铵0.1～0.15mg/kg,气管插管。麻醉维持:丙泊酚6～8mg.kg-1.h-1、维库溴铵0.1mg.kg-1.h-1和雷米芬太尼7～10μg.kg-1.h-1。在稳定的麻醉和手术状况下,分别单次给予患者氯胺酮0.5mg/kg(K组)或等量的生理盐水(S组),记录给药前(基础值)、给药后5、10、15、20、25和30min七个时点MAP、HR、RE、SE和BIS的数值。结果K组和S组MAP、HR、RE、SE和BIS的基础值差异均无统计学意义。K组RE、SE和BIS在给药后迅速升高,然后逐渐下降,在给药后10min达到峰值,分别比基础值升高了43.8%(P<0.01)、43.2%(P<0.01)和28.8%(P<0.01)。RE和SE增加的幅度显著高于BIS,熵指数和BIS增加持续的时间分别为25min和20min。S组在给药后RE、SE和BIS值与基础值相比差异均无统计学意义。K组和S组在给药前后MAP和HR变化差异无统计学意义。结论在丙泊酚-雷米芬太尼麻醉期间,单次加入小剂量的氯胺酮,熵指数和BIS均不能准确反映其真正的麻醉深度。     

肌松药对异丙酚诱导期脑电熵和脑电双频指数的影响

目的：探讨维库溴铵、琥珀胆碱对异丙酚诱导期脑电熵和脑电双频指数（bispectral index,BIS）的影响。方法：靶控输注异丙酚进行诱导,当患者OAA/S评分≤1分时置入喉罩,机械通气。调节异丙酚靶控浓度,使效应室浓度（effect-site concentration,Ce）维持在2.0μg/mL或3.0μg/mL,稳定5min。维库溴铵2.0组（V2.0组）和维库溴铵3.0组（V3.0组）分别在异丙酚Ce稳定在2.0μg/mL或3.0μg/mL时静脉推注维库溴铵0.1mg/kg,琥珀胆碱2.0组（S2.0组）和琥珀胆碱3.0组（S3.0组）则静脉推注琥珀胆碱1mg/kg,两组对照组（C2.0组,C3.0组）给予等容量的生理盐水。记录麻醉诱导前、肌松药静脉推注前（基础值）及静脉给药后第1～5分钟的BIS、反应熵（respect entropy,RE）、状态熵（state entropy,SE）。结果：与基础值比较,V2.0组、S2.0组和C2.0组静脉给药后BIS、RE、SE下降（P〈0.05）,V3.0组和S3.0组各指标变化差异无统计学意义（P〉0.05）。S2.0组和S3.0组在给予琥珀胆碱后第2分钟时点RE、SE升高（P〈0.05）,但BIS变化差异无统计学意义（P〉0.05）。V2.0组、V3.0组、S2.0组和S3.0组分别与相同异丙酚Ce对照组比较,静脉推注肌松药前后SE、BIS差异均无统计学意义（P〉0.05）,仅RE在给予琥珀胆碱后第2分钟时点升高（P〈0.05）。结论：肌松药对脑电熵和BIS的影响与镇静深度有关,在较浅的镇静状态下,肌松药可引起BIS、RE、SE数值下降;肌松药对脑电熵和BIS的影响与肌松药的种类无关。     

熵指数监测全麻患者镇静水平的准确性

目的 评价反应熵和状态熵监测全麻患者镇静水平的准确性.方法 择期行腹部手术患者20例,ASAⅠ或Ⅱ级,入室后监测反应熵(RE)、状态熵(SE)及脑电双频谱指数(BIS),静脉注射异丙酚、维库溴铵和芬太尼麻醉诱导,气管插管后机械通气,吸入七氟烷、间断静脉注射维库溴铵和芬太尼维持麻醉.分别于入室时、意识消失前10min、意识消失即刻、气管插管时、手术1 h、意识恢复前10 min、意识恢复即刻、拔管后10 min时记录RE、SE和BIS.结果 RE、SE和BIS在意识改变前后差异均有统计学意义(P＜0.05),RE、SE和BIS判断意识消失的临界值分别为76、73和68,灵敏度分别为94%、95%和92%,特异度分别为92%、94%和9l%,临界值判断意识消失的准确度分别为93%、95%、94%;判断意识恢复的临界值分别为82、75和70,灵敏度分别为95%、95%和91%,特异度分别为93%、96%和93%,临界值判断意识恢复的准确度分别为98%、96%和97%.结论 熵指数能够准确地监测全麻患者镇静水平.     

不同剂量舒芬太尼对麻醉诱导时病人异丙酚效应室靶浓度及气管插管反应的影响

目的 观察在脑电双频谱指数（BIS）监测下不同剂量舒芬太尼对麻醉诱导时病人异丙酚效应室靶浓度（Ce）及气管插管反应的影响，以探讨舒芬太尼复合异丙酚麻醉诱导的合适用量。方法 择期全麻手术病人60例，ASAⅠ级或Ⅱ级，年龄20-60岁，体重45-80 kg，随机分为3组（n= 20），均静脉注射咪达唑仑0．05 mg／kg后开始靶控输注异丙酚（初始靶浓度为2μg／ml），同时分别静脉注射芬太尼3μg／kg（F组）、舒芬太尼0．3μg／kg（S1组）、舒芬太尼0．45μg／kg（S2组）。待病人意识消失后或BIS降至75以下时静脉注射维库溴铵0．12 mg／kg，BIS降至55以下时进行气管插管，机械通气。调整异丙酚靶浓度维持BIS 40-60。记录入室时（基础值）、气管插管前即刻、插管后即刻、插管后3、5、10、15 min时BP、MAP、HR、BIS及Ce。结果 与F组和S1组比较，S2组插管后即刻和插管后3、5、10、15min时Ce降低（P〈0．05），但F组和S1组各时点比较差异无统计学意义（P〉0．05）。与基础值比较，F组和S1组插管后即刻和插管后3 min时BP、MAP和HR增加（P〈0.05）。与S2组比较，F组和S1组插管后即刻和插管后3 min时BP、MAP和HR增加（P〈0．05）。F组和S1组各时点BP、MAP和HR比较差异均无统计学意义（P〉0．05）。结论 病人在靶控输注异丙酚麻醉诱导时，舒芬太尼抑制气管插管心血管反应的效价是芬太尼的7倍。     

舒芬太尼复合异丙酚麻醉下体外循环冠脉搭桥术患者双频谱指数与熵指数的关系

目的评价非肌松、深麻醉状态下,双频谱指数(BIS)反映麻醉深度的准确性。方法选择ASAⅢ级的冠脉搭桥术患者59例,麻醉诱导:静脉注射异丙酚2 mg／kg、舒芬太尼1μg／kg、罗库溴铵0．6 mg／kg,术中麻醉维持采用静脉持续输注异丙酚3-4 mg·kg-1·h-1、舒芬太尼1μg·kg-1·h-1。于麻醉诱导前、麻醉诱导开始后1、2、3、4 min、气管插管后即刻、气管插管后1 min、切皮后即刻和劈胸骨后即刻记录BIS、状态熵(SE)和反映熵(RE)。结果与麻醉诱导前相比,麻醉诱导开始后1、2、3、4 min和气管插管后即刻、气管插管后1 min、切皮后即刻及劈胸骨后即刻BIS、SE和RE均下降(P<0．05)。与SE相比,RE在各观察点均升高(P<0．01)。麻醉诱导期间BIS与SE和RE各时间点观察值之间呈明显正相关,r分别为0．898、0．908(P<0．01)。结论在非肌松、深麻醉状态下,BIS对舒芬太尼复合异丙酚静脉麻醉深度的监测不受肌电活动的影响。     

艾司洛尔、拉贝洛尔和尼卡地平对气管插管期间心血管反应、脑电双频指数和熵指数的影响

目的探讨艾司洛尔、拉贝洛尔和尼卡地平对气管插管期间心血管反应、腑电双频指数(BIS)和熵指数的影响。方法 60例择期腹部手术的患者,随机均分为四组:艾司洛尔组、拉贝洛尔组和尼卡地平组、生理盐水组。四组均采用丙泊酚分步靶控输注诱导,BIS≤80时各组分别静注艾司洛尔0.3 mg/kg、拉贝洛尔0.04 mg/kg、尼卡地平0.03 mg/kg 和生理盐水。当 BIS≤50后1 min行气管插管。观察反应熵(RE)、状态熵(SE)、BIS、HR 和 MAP 的变化。结果艾司洛尔组、拉贝洛尔组和尼卡地平组 MAP、HR 在插管后1 min 显著高于插管前1 min(P<0.05或 P<0.01)。各组RE、SE、BIS 插管前后差异无统计学意义。结论艾司洛尔、拉贝洛尔或尼卡地平均可减轻患者气管插管时的心血管反应,但对 BIS、RE、SE 无显著影响。     

艾司洛尔对患者麻醉诱导气管插管时脑电双频谱指数的影响

目的 评价艾司洛尔对患者麻醉诱导气管插管时脑电双频谱指数(BIS)的影响,探讨其抑制气管插管心血管反应的机制.方法 择期手术患者40例,ASAⅠ级或Ⅱ级,年龄20～60岁,随机分为2组(n=20):艾司洛尔组(E组)和对照组(C组).静脉注射咪达唑仑0.1 mg/kg、芬太尼5 μg/kg和维库溴铵0.1 mg/kg行麻醉诱导.麻醉诱导前E组静脉注射艾司洛尔1 mg/kg,并静脉输注250 μg·kg-1·min-1,C组静脉注射等容量的生理盐水.记录静脉注射艾司洛尔前、麻醉诱导前、气管插管前、气管插管后1、2、5 min时心率(HR)、平均动脉压(MAP)和BIS.结果 静脉注射艾司洛尔前、麻醉诱导前及气管插管前两组MAP、HR差异无统计学意义(P＞0.05);与气管插管前比较,两组气管插管后HR、MAP升高,C组BIS升高(P＜0.05);与C组比较,E组气管插管后HR、MAP及BIS降低(P＜0.05).结论 艾司洛尔可降低麻醉诱导气管插管时BIS水平,提示其抑制气管插管心血管反应的机制与其抗伤害作用有关.     

靶控输注雷米芬太尼对脑电双频指数的影响

目的研究不同靶浓度的雷米芬太尼对脑电双频指数（BIS）的影响。方法60例择期行全麻手术的病人随机分成R0、R2、R4、R6四组,每组15例。病人进入手术室静卧5min取得基础数据后,给予血浆靶浓度为3μg／ml的丙泊酚,5min后依分组情况分别给予血浆靶浓度为0、2、4、6ng／ml的雷米芬太尼,3min后行气管插管,并记录数据至气管插管后5min。所有病人均未给予术前药,病人意识消失后给予0．1mg／kg的维库溴铵,研究中应用辅助或机械通气以维持PET CO2在35～45mmHg。记录每分钟的MAP、HR、BIS,并将病人人室后（T0）、给雷米芬太尼前（T1）、气管插管前（T2）及气管插管后5min内的最大值（T3）进行统计分析。结果2～6ng／ml的雷米芬太尼对BIS没有影响。R2组病人气管插管后存在插管反应,BIS明显升高,BIS变化趋势与MAP、HR变化趋势相一致。结论雷米芬太尼对BIS没有影响。BIS可以用来指导丙泊酚的用量,4ng／ml的雷米芬太尼是较佳的气管插管剂量。     

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。     

七氟醚、异氟醚不同呼气末浓度对熵和脑电双频指数的影响

目的 观察不同呼气末浓度的七氟醚和异氟醚对熵、脑电双频指数(BIS)及血流动力学的影响.方法 40例ASA Ⅰ或Ⅱ级全麻手术患者随机均分为七氟醚组(Ⅰ组)和异氟醚组(Ⅱ组).麻醉诱导用丙泊酚1 mg/kg,1 min后吸入七氟醚或异氟醚;维持反应熵(RE)、状态熵(SE)、BIS45～55,6 min后置入喉罩.调节吸入浓度使两组患者呼气末浓度分别为0.4、0.6、0.8、1.0和1.3MAC时各维持10 min,记录RE、SE、BIS、HR和MAP.结果 两组患者不同呼气末浓度七氟醚和异氟醚RE、SE、BIS随浓度增加而逐渐下降(P<0.05),HR逐渐减慢、MAP逐渐降低(P<0.05).两组间各指标差异均无统计学意义.RE、SE、BIS间直线相关性随呼气末浓度增大相关系数有增加趋势.结论 熵和BIS均能有效监测七氟醚、异氟醚麻醉深度.     

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.