听觉诱发电位指数在老年高血压患者异氟醚麻醉中的应用

目的　研究听觉诱发电位指数 (AEPI)调控异氟醚麻醉深度对老年高血压患者手术中血压控制的可行性。方法　择期行胃切除术合并高血压的老年患者 2 8例 ,ASAⅡ～Ⅲ级 ,随机分两组 ,每组 14例。Ⅰ组通过AEPI监测对麻醉深度行反馈调控 ;Ⅱ组不用AEPI调控 ,仅根据血液动力学的变化来调整麻醉深度。两组患者麻醉诱导均用芬太尼、丙泊酚和琥珀胆碱 ;麻醉维持用氧化亚氮、异氟醚吸入。记录基础值、插管时、插管后 5min、切皮时、术中探查时、停药时、睁眼时和拔管时 8个时间点的HR、SBP、DBP、MAP和AEPI。结果　Ⅰ、Ⅱ组在插管时的SBP、DBP和MAP均显著低于基础值 (P <0 0 5 )。但插管后 5min时与基础值比较 ,Ⅱ组血压有回升 ,Ⅰ组仍降低 (P <0 0 5 )。术中切皮时、探查时、停药时 ,Ⅰ组血液动力学变化较为平稳 ,且低于基础值 (P <0 0 5 ) ;而Ⅱ组中 ,在切皮时和探查时明显上升 (P <0 0 5 )。两组患者在基础值、睁眼时及拔管时的AEPI值均无明显差异 ;但术中各时点Ⅰ组明显低于Ⅱ组 (P <0 0 5 )。结论　在老年高血压患者手术中 ,通过AEPI的监测调节异氟醚麻醉深度可维持稳定的血液动力学 ,有利于保障患者的安全     

老年人腹腔镜手术中血液动力学的变化

目的探讨老年人腹腔镜手术中血液动力学的变化。方法选择ASAⅠ～Ⅱ级,年龄20～80岁的行择期腹腔镜胆囊切除手术病人30例,其中大于65岁的15例,为Ⅰ组,20～65岁的15例为Ⅱ组。给予芬太尼0.2μg/kg、琥珀胆碱2mg/kg,丙泊酚靶控输注诱导和维持麻醉,依据听觉诱发电位指数(AEPI)调整,使两组维持同样麻醉深度;分别于气腹前(T1)、气腹后1min(T2)、5min(T3)、10min(T4)、20min(T5)及放气后5min(T6)连续观察心率(HR)、血压(SBP、DBP、MAP)、心排血量(CO)、主动脉每搏流量(SV)、峰速度(PV)、全身血管阻力(SVR)。结果同气腹前比较,Ⅰ、Ⅱ组病人气腹后CO、SV、PV降低,MAP、SVR增大,在放气后SV、CO、PV上升,MAP、SVR降低,尤以Ⅰ组变化更大(P<0.01)。结论腹腔镜手术中,气腹对老年人的血液动力学的影响较大,应引起重视。     

不同静脉麻醉药对听觉诱发电位指数的影响

目的　研究丙泊酚、咪唑安定、硫喷妥钠、氯胺酮麻醉时听觉诱发电位指数 (AEPI)的变化规律。方法　 4 8例择期手术拟行全身麻醉、无听力障碍和严重神经疾患、非颅脑手术病人 ,随机分为四组。Ⅰ组 (14例 )静注丙泊酚 2mg/kg ;Ⅱ组 (13例 )静注咪唑安定 0 2mg/kg ;Ⅲ组 (11例 )静注硫喷妥钠 5mg/kg ;Ⅳ组 (10例 )静注氯胺酮 2mg/kg。随后芬太尼 5 μg/kg、维库溴铵 0 15mg/kg静注 ,肌松满意后气管插管。记录麻醉诱导前、诱导中、诱导后插管前、插管后的HR、BP、SpO2 ,观察整个诱导期AEPI的变化规律。结果　Ⅰ、Ⅱ、Ⅲ组病人用药后AEPI进行性降低至 30以下。降到 30以下的平均时间分别为Ⅰ组 (6 2± 2 5 )分钟、Ⅱ组 (3 2± 1 9)分钟、Ⅲ组 (5 1± 2 6 )分钟 ;Ⅳ组病人AEPI无明显下降。插管后AEPI有上升趋势 ,吸入异氟醚后 (呼出气浓度 >0 8Vol% )能维持AEPI30以下 ;Ⅳ组病人插管后AEPI不稳定。结论　丙泊酚、咪唑安定、硫喷妥钠降低AEPI,而氯胺酮对AEPI无明显影响。AEPI在丙泊酚、咪唑安定、硫喷妥钠麻醉中可作为麻醉深度监测的指标之一。     

丙泊酚靶控输注联合脑电双频指数在高龄患者麻醉诱导期的应用

目的 观察丙泊酚靶控输注(TCI)联合脑电双频指数(BIS)在高龄患者麻醉诱导期的血流动力学变化及应激反应.方法 高龄全麻胃癌根治手术患者45例,随机均分为三组.Ⅰ组以BIS值为控制目标;Ⅱ、Ⅲ组以临床指征为目标.Ⅰ、Ⅱ组麻醉诱导采用丙泊酚TCI,Ⅲ组以人工法输注丙泊酚,而后以恒速泵入.记录入室静卧15 min (T0),意识消失时(T1),气管插管即刻(T2),插管后1 min (T3)、3 min (T4)、5 min (T5)的HR、SBP、DBP;并测定血浆皮质醇(Cor)、血糖(Glu)及去甲肾上腺素(NE)、肾上腺素(E)的浓度变化.结果 T1、T2时三组SBP、DBP明显低于T0时(P＜0.05);T3时Ⅰ、Ⅱ组SBP明显低于Ⅲ组,Ⅲ组HR明显快于Ⅰ组(P＜0.05).T2时三组Cor浓度明显低于T0时(P＜0.05),T3、T4时Ⅱ、Ⅲ组Cor浓度明显高于T2时(P＜0.05).T3时三组NE、E浓度明显高于T0时(P＜0.05),T5时三组NE、E浓度明显低于T3时(P＜0.05).结论 在丙泊酚用于高龄患者麻醉诱导中,以BIS指导丙泊酚TCI在麻醉诱导期能够较好地维持适当的麻醉深度,降低气管插管引起的应激反应,维持麻醉诱导期血流动力学的平稳.     

不同剂量雷米芬太尼对全麻诱导期血液动力学和血浆皮质醇浓度的影响

目的观察不同剂量雷米芬太尼诱导插管对血液动力学和血浆皮质醇浓度的影响。方法40例全麻病人随机均分为四组:芬太尼组(Ⅰ组,芬太尼2μg/kg)和不同剂量雷米芬太尼组(Ⅱ组0·5μg/kg,Ⅲ组1·0μg/kg,Ⅳ组1·25μg/kg)。诱导使用咪唑安定0·025mg/kg、芬太尼2μg/kg或雷米芬太尼0·5、1·0、1·25μg/kg、丙泊酚1·5mg/kg和罗库溴铵0·7mg/kg。分别于麻醉诱导前1min、诱导后1min及插管后3min内每隔1分钟记录SBP、DBP、HR,分别在诱导前5min、插管后4、6min测血浆皮质醇浓度。结果各组在诱导后SBP、DBP均明显下降,其中Ⅲ、Ⅳ组下降更明显。插管后,Ⅰ、Ⅱ组SBP、DBP明显上升,HR增快。Ⅲ、Ⅳ组SBP分别在插管后2、1min下降。各时点Ⅲ、Ⅳ组SBP、DBP、HR与Ⅰ组相比显著下降。Ⅰ、Ⅱ组血浆皮质醇浓度在插管后4min明显上升。结论雷米芬太尼1·0、1·25μg/kg虽可以有效抑制气管插管引起的心血管不良反应,但诱导期间低血压和呼吸抑制的发生率较高。     

硬膜外麻醉下靶控输注丙泊酚镇静对血液动力学的影响

目的 观察靶控输注（TCI）丙泊酚镇静对硬膜外麻醉患者血液动力学的影响,并确定血压降低50％的靶控浓度。方法 28例择期行硬膜外麻醉手术的患者,ASA Ⅰ～Ⅱ级,年龄17～67岁,术中采用丙泊酚TCI镇静,靶控浓度从0．4μg／ml开始,以0．4μg／ml梯度逐渐上升,直至患者入睡并维持该浓度直至手术结束。麻醉中观察并记录SBP、DBP、MAP、HR和SpO2的变化。结果 MAP和HR随靶控浓度的升高而降低,降低的平均幅度分别为23％和11％。MAP降低50％的靶控浓度为6．31μg／ml。结论 硬膜外麻醉下丙泊酚TCI镇静时,达意识消失状态时的靶控浓度远低于EC50,镇静深度易于调控,血液动力学较稳定。     

不同剂量芬太尼复合丙泊酚对小儿全麻诱导期应激反应的影响

目的观察不同剂量芬太尼诱导气管插管对小儿血流动力学和血浆肾上腺素(E)、去甲肾上腺素(NE)的影响。方法40例择期全麻患儿,按不同剂量芬太尼随机均分四组:Ⅰ组1.0μg/kg,Ⅱ组2.0μg/kg,Ⅲ组2.5μg/kg,Ⅳ组3.0μg/kg。诱导使用咪唑安定0.1mg/kg,芬太尼1.0、2.0、2.5、3.0μg/kg,丙泊酚2.5mg/kg和维库溴铵0.1mg/kg。分别于麻醉诱导前(T0)、诱导后2min(T1)、插管后1、2min(T2、T3)记录HR、SBP和DBP。分别于T0、插管后3、5min(T4、T5)测血浆E和NE浓度。结果与T0时比较,各组患儿在T1时SBP、DBP均明显下降(P<0.05或P<0.01);T2、T3时Ⅰ组SBP明显增高(P<0.01),DBP增高,HR增快,但差异无统计学意义;Ⅱ~Ⅳ组SBP有所下降(P<0.05或P<0.01)。T1~T3时Ⅱ~Ⅳ组SBP及Ⅲ、Ⅳ组DBP较Ⅰ组降低(P<0.05或P<0.01);Ⅳ组HRT1时较Ⅰ组减慢(P<0.05)。T2、T3时Ⅱ~Ⅳ组HR较Ⅰ组减慢(P<0.05)。Ⅰ组血浆E和NE浓度在T4时明显上升(P<0.05或P<0.01)。结论芬太尼2.0~2.5μg/kg能较好地抑制小儿全麻诱导气管内插管时的应激反应。     

术前肌注咪唑安定对听觉诱发电位指数和血浆内皮素的影响

目的　比较和评价麻醉手术前使用咪唑安定或苯巴比妥钠对患者焦虑、顺行性遗忘、听觉诱发电位指数和血浆内皮素的影响。方法　 4 0例年龄 2 0～ 6 0岁、ASAⅠ～Ⅱ级的择期手术患者 ,随机分为两组。Ⅰ组麻醉前 30min肌肉注射苯巴比妥钠 0 1g +阿托品 0 5mg(n =2 0 ) ;Ⅱ组于麻醉前 30min肌肉注射咪唑安定 0 0 6mg/kg(41～ 6 0岁 )和 0 0 8mg/kg(2 0～ 4 0岁 ) +阿托品 0 5mg(n=2 0 )。分别于用药前后测定患者收缩压 (SBP)、舒张压 (DBP)、心率 (HR)、指脉搏血氧饱和度(SpO2 )、呼吸频率 (RR)、焦虑视觉模拟评分 (AVAT)、听觉诱发电位指数 (AEPI)、顺行性遗忘程度和血浆内皮素 (ET 1)浓度变化。结果　两组患者在用药前后SBP、DBP、HR、SpO2 和RR无明显变化(P >0 0 5 ) ;Ⅰ组在用药前后AVAT、AEPI和ET 1浓度变化无差异 (P >0 0 5 ) ,顺行性遗忘率 2 0 % ;Ⅱ组用药后 30minAVAT、AEPI和ET 1浓度均低于用药前 (P <0 0 5 ) ,顺行性遗忘率为 75 %显著高于Ⅰ组 (P <0 0 1)。结论　与苯巴比妥钠相比 ,咪唑安定可有效减轻患者麻醉手术前焦虑情绪 ,获得更好的顺行性遗忘和镇静效果 ,且能减轻麻醉手术前应激反应     

末梢血管收缩反应预测气管插管血液动力学变化

目的通过末梢血管收缩反应预测气管插管引起的血液动力学变化,提供个体化气管插管所需的麻醉深度。方法末梢血管收缩反应通过强直电刺激(50 Hz、50 mA持续5 s)诱发的末梢灌注指数(tip perfusion index,TPI)变化进行监测。24例ASAⅠ~Ⅱ级颅脑外科择期手术患者,麻醉诱导:咪唑安定0.06 mg/kg、芬太尼4μg/kg,丙泊酚0.25 mg.kg-1.min-1恒速输注。意识消失后每间隔1分钟电刺激一次,记录每次电刺激前后TPI的减少值(△TPI)和插管前后SBP、DBP和HR的增加值(△SBP、△DBP和△HR)。观察组(n=12),△TPI<10%刺激前值时行气管插管;对照组(n=11),不考虑△TPI的变化而根据操作者的经验决定插管时机。记录诱导前、插管前、插管后即刻、1、2和3 min时BIS、SBP、DBP和HR的值。结果插管即刻,观察组比对照组丙泊酚输注时间长(P<0.01)、用量大(P<0.01);插管后每一时间点,对照组SBP、DBP和HR都比观察组高(P<0.01)。组内比较:对照组插管前后SBP、DBP和HR明显增高(P<0.01);观察组插管前后各指标无明显变化。电刺激诱发的△TPI分别与插管引起的△SBP、△DBP和△HR成正相关(r=0.672、0.434和0.236,P<0.01)。结论电刺激诱发的末梢血管收缩反应性可有效预测气管插管引起的血液动力学变化幅度。     

丙泊酚伍用亚麻醉剂量氯胺酮对创伤病人麻醉诱导时血液动力学的影响

目的探讨丙泊酚伍用亚麻醉剂量氯胺酮对创伤病人全麻诱导时血液动力学的影响。方法将60例创伤休克病人随机分为丙泊酚组(Ⅰ组),丙泊酚复合亚麻醉剂量氯胺酮组(Ⅱ组),每组30例。诱导时依次静注芬太尼2μg/kg、咪唑安定0.05 mg/kg、罗库溴铵0.8 mg/kg,同时Ⅰ组丙泊酚血浆靶控输注(TCI)4μg/ml,Ⅱ组丙泊酚TCI 2μg/ml加氯胺酮0.5 mg/kg。采用Bioz.com阻抗法血液动力学连续监护系统监测HR、BP、心脏指数(CI)、每搏指数(SI)、周身血管阻力指数(SVRI)、加速度指数(ACI)等指标。结果与基础值比较,两组HR诱导时均显著增快(P<0.05)。Ⅰ组SBP、CI、SI、SVRI诱导时均显著下降(P<0.05),而Ⅱ组以上各项指标均无显著变化。Ⅰ组在麻醉诱导时SBP、CI、SI较Ⅱ组显著下降(P<0.05),其余各时点也有一定下降,但差异无显著意义。两组间在各时点的HR、DBP、ACI差异均无显著意义。结论丙泊酚伍用亚麻醉剂量氯胺酮有利于保持创伤病人全麻诱导时血液动力学的稳定。     

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.