甲基强的松龙与神经节苷脂治疗大鼠急性脊髓损伤

目的探讨早期联合应用大剂量甲基强的松龙(MP)及神经节苷脂(GM1)对大鼠急性脊髓损伤的治疗效果.方法改良Allen's打击法致伤36只大鼠T10～T12脊髓建立急性脊髓损伤模型,随机分为对照组、MP治疗组(应用大剂量MP)及MP+GM1治疗组(早期联合应用大剂量MP及GM1),观察大鼠肢体功能恢复、运动神经元数目及截面积以及胆碱脂酶活性变化,TUNEL标记检测凋亡神经元细胞,比较各组间差别.结果治疗组大鼠神经元细胞结构退变较对照组轻,BBB评分、运动神经元数目及截面积以及胆碱脂酶(CHE)活性较对照组明显提高,尤以MP+GM1组更明显,脊髓凋亡神经元数对照组较实验组明显增多(P＜0.05).结论甲基强的松龙及神经节苷脂对急性脊髓损伤大鼠的脊髓功能具有保护作用,二者联合应用具有协同作用.     

神经节苷脂有髓损伤的保护作用观察

目的：观察神经节苷脂对损伤脊髓神经组织的保护作用,并初步探讨其作用机制。方法：重度脊髓损伤大鼠随机分为对照组及神经节苷脂治疗组（n=15)。在蛛网膜下腔注射生理盐水20μl或神经节苷脂30μg。观察体重变化局部血流量、凋亡细胞原位标记、神经功能评价和定量组织学分析。结果：局部血流量2组无明显差异,治疗组存活8率、体重、神经功能评分和残余神经组织面积明显高于对照组,而TUNEL阳性细胞数量明显低于对照组。结论：神经节苷脂对损伤脊髓组织有明显保护作用,可能是通过对神经细胞凋亡的阻断来发挥作用的。     

复方丹参对大鼠脊髓损伤后细胞凋亡及诱导型一氧化氮合酶表达的影响

目的:探讨大鼠脊髓损伤后应用复方丹参对细胞凋亡及诱导型一氧化氮合酶(iNOS)表达的影响。方法:成年大鼠随机分为正常组、脊髓损伤后应用复方丹参组(组)和应用生理盐水对照组(组),损伤后不同AB时间点(8h、1d、3d、7d、14d、28d)处死大鼠,用HE染色观察损伤脊髓组织病理变化,原位末端标记法(TUNEL法)标记凋亡细胞,用免疫组化染色检测iNOS阳性细胞。结果:HE染色镜检发现脊髓组织病理学改变A组明显轻于B组。A、B两组均发现凋亡细胞及iNOS表达,神经细胞凋亡指数及iNOS表达均为B组>A组(P<0.01)。结论:复方丹参能抑制大鼠脊髓损伤后细胞凋亡及iNOS表达。     

牵张性脊髓损伤后神经细胞中Caspase-3表达及其作用的实验研究

目的:观察大鼠牵张性脊髓损伤后脊髓神经细胞中半胱氨酸天冬氨酶3(Caspase-3)的表达及其在神经细胞凋亡中的作用。方法:大鼠脊髓T13~L2经牵张损伤,皮层体感诱发电位监测P1-N1波幅下降至术前波幅70%后维持10m in,分别于术后6h、1、4、7、14、21d处死取材。采用流式细胞仪、原位末端脱氧核苷酸转移酶介导的生物素脱氧尿嘧啶核苷酸缺口末端标记法(TUNEL法)、免疫组织化学检测等方法观察大鼠脊髓神经细胞中Caspase-3表达变化及神经细胞凋亡情况,测定Caspase-3活性。结果:脊髓损伤后神经细胞凋亡率、TUNEL阳性细胞数、Caspase-3免疫组织化学阳性表达及Caspase-3活性测定均较空白对照组及椎板切除组显著升高(P<0.05或0.01),前三项指标改变趋势大致相同,均为术后7d达高峰,而Caspase-3活性则术后4d达高峰。结论:大鼠牵张性脊髓损伤后神经细胞中Caspase-3表达增高、Caspase-3活性增强,是检测神经细胞凋亡的早期生物学指标,对认识脊髓损伤机制具有一定的意义。     

富氢生理盐水对兔脊髓损伤神经细胞凋亡及凋亡相关蛋白表达的影响

目的探讨富氢生理盐水腹腔注射对家兔脊髓损伤神经细胞凋亡及凋亡相关蛋白表达的影响。方法选用30只雄性家兔,随机分为3组,即健康组、对照组和治疗组,每组10只。对照组采用对生理盐水对脊髓损伤家兔进行治疗,治疗组采用富氢生理盐水治疗对脊髓损伤家兔。采用Allen脊髓重物打击损伤法造模,并对家兔脊髓损伤后后肢行为功能评定。治疗结束后对比健康组、对照组和治疗组脊髓神经细胞凋亡情况,并检测治疗1 d、3 d、6 d、10 d后Bcl-2、Bax和caspase-3蛋白表达情况。结果 Basso分级评分结果显示,家兔脊髓损伤模型造模成功。造模后家兔脊髓神经细胞大量凋亡。与治疗前和对照组相比,给药富氢生理盐水后家兔神经细胞凋亡数明显减少。同时,对照组caspase-3蛋白表达高于健康组(P0.001)和治疗组(P0.001);与健康组相比,治疗组caspase-3蛋白表达水平较高(P0.01)。此外,治疗10 d后,治疗组Bax蛋白表达量低于对照组(t=2.263,P=0.035),但高于健康组(t=1.975,P=0.042);治疗组Bcl-2蛋白表达量高于对照组(t=0.463,P0.05),显著高于健康组(t=2.486,P=0.028);治疗组Bax/Bcl-2蛋白表达低于对照组,差异具有统计学意义(t=2.354,P=0.031)。结论腹腔注射富氢生理盐水显著降低了家兔脊髓损伤神经细胞凋亡及Bax/Bcl-2水平和caspase-3蛋白的表达。     

大剂量甲基强地松龙对大鼠脊髓损伤后iNOS表达及细胞凋亡的影响

目的：探讨大鼠脊髓损伤后应用大剂量甲基强地松龙(MP)对诱导型一氧化氮合酶(iNOS)表达及细胞凋亡的影响。方法：成年大鼠随机分为脊髓损伤后应用大剂量甲基强的松龙治疗组(A组)和应用生理盐水对照组(B组)，损伤后不同时间点(4h、8h、1d、3d、7d、14d、21d)按Tarlov标准评价大鼠双后肢神经功能恢复情况，然后处死。用HE染色观察损伤脊髓组织病理变化，用免疫组化染色检测iNOS阳性细胞，原位末端标记法(TUNEL法)标记凋亡细胞。结果：HE染色镜检发现脊髓组织病理学改变A组明显轻于B组。A、B两组均发现凋亡细胞及iNOS表达，神经细胞凋亡指数及iNOS表达均为B组＞A组(P＜0．01)。结论：大剂量甲基强的松龙能抑制大鼠脊髓损伤后iNOS表达及细胞凋亡。     

神经营养因子复合剂N6对脊髓损伤神经细胞凋亡的作用

[目的]研究神经营养因子复合剂(N6)对脊髓损伤后神经细胞凋亡的作用。[方法] Wistar大鼠(SPF级) 48只随机分为4组,每组12只。假手术组,只摘除椎板未损伤脊髓;单纯脊髓损伤组(损伤组),采用Allen法经NYU脊髓损伤撞击器制备急性脊髓损伤模型;脊髓损伤+生理盐水治疗组(INS组),制备急性脊髓损伤模型,并给予蛛网膜下腔注射生理盐水治疗;脊髓损伤+N6治疗组(IN6组),制备急性脊髓损伤模型,并给予蛛网膜下腔注射N6治疗。损伤后72 h取材,采用HE染色对脊髓组织进行标记;免疫组化方法检测Caspase 3蛋白的表达;半定量逆转录-聚合酶链式反应(RT-PCR)测定凋亡相关基因Caspase 3、Fas、Bax、Bcl2、P53 mRNA在脊髓组织中的表达变化。[结果]免疫组化结果显示:假手术组脊髓神经细胞很少有Caspase 3表达,假手术组较损伤组和INS组的Caspase 3阳性表达细胞数明显减少(P0.01);与之类似,IN6组较损伤组和INS组Caspase-3阳性表达细胞数也明显减少(P0.01)。RT-PCR检测到Caspase-3、Fas和P53 mRNA水平,IN6组较损伤组和INS组明显降低(P0.05);而Bcl2/Bax值,IN6组较损伤组和INS组明显升高(P0.05)。[结论]神经营养因子复合剂N6能明显抑制脊髓损伤后神经细胞的凋亡。     

甲基强的松龙对大鼠脊髓损伤后神经细胞凋亡的影响及其机理

目的研究甲基强的松龙(MP)对大鼠横断性脊髓损伤(SCI)后神经细胞凋亡的影响及其作用机理.方法60只成年Wistar大鼠随机分成正常对照组、脊髓损伤组和MP治疗组,每组20只,MP治疗组在横断T10脊髓组织后30min经尾静脉给予MP治疗,损伤组和对照组未予任何治疗.MP治疗组和脊髓损伤组大鼠于脊髓损伤后8h、24h、3d和1周取材,采用透射电镜、TUNEL染色观察细胞凋亡情况,采用免疫组织化学染色观察Fas、半胱氨酸蛋白酶(caspase)-8和caspase-3在SCI前后的变化情况,采用改良Tarlov评分方法观察大鼠后肢运动功能.结果SCI后24h大鼠后肢运动功能逐渐恢复,MP治疗组大鼠的后肢运动功能恢复优于损伤组,7d后尤其明显.TUNEL染色和电镜检查证实SCI后8h即有凋亡细胞出现,其中既有神经元也有胶质细胞3d凋亡细胞数达到高峰;7d仍有凋亡细胞存在,但已明显减少;各时间点治疗组凋亡细胞数量明显少于损伤组(P＜0.05).治疗组和损伤组在SCI后8h可以检测到少量的Fas和caspase-8阳性神经元及胶质细胞,Fas和caspase-8的表达在SCI后3d达到高峰,7d表达下降,各时间点治疗组的Fas和caspase-8灰度值明显大于损伤组,二者有显著性差异(P＜0.05).治疗组和损伤组caspase-3的表达在SCI后8h均逐渐增加(与对照组相比),7d达到高峰,治疗组灰度值大于损伤组,但二者无显著性差异.结论MP能抑制大鼠脊髓横断性脊髓损伤后的神经细胞凋亡,但不能推迟细胞凋亡出现的高峰时间;MP抑制细胞凋亡的途径可能通过非特异性抑制Fas和caspase-8的表达来实现.     

L-丝氨酸对大鼠神经细胞凋亡与内源性神经干细胞增生的影响

目的 观察大鼠急性脊髓损伤(SCI)后L-丝氨酸(L-Ser)抑制神经细胞凋亡与促进内源性神经干细胞(eNSCs)增殖的作用. 方法 健康SD成年雄性大鼠100只,随机分为5组(n=20):假手术组(只行椎板切除,不损伤脊髓)、单纯损伤组(制备SCI模型后腹腔注射生理盐水)、L-Ser治疗组(制备SCI模型后腹腔注射L-Ser)、D-环丝氨酸(DCS)治疗组(制备SCI模型后腹腔注射DCS)和DCS拮抗组(制备SCI模型后腹腔注射L-Ser和DCS).1、3、5、7d观察并记录各组大鼠斜板试验的斜坡角度和BBB运动评分,观察脊髓前角神经细胞数、检测细胞凋亡和Brdu和Nestin双标阳性细胞的表达. 结果 术后3d开始,L-Ser治疗组的斜坡角度和BBB运动评分均大于单纯损伤组、DCS治疗组和DCS拮抗组,差异有统计学意义(P＜0.05),且随着治疗时间的增加,斜坡角度呈现递增趋势.L-Ser治疗组的脊髓前角神经细胞数和Brdu/Nestin阳性细胞数明显多于单纯损伤组、DCS治疗组和DCS拮抗组,而脊髓前角神经凋亡细胞数明显少于其他3组,差异均有统计学意义(P＜0.05).DCS治疗组、DCS拮抗组和单纯损伤组间的斜坡角度、BBB运动评分、脊髓前角神经细胞数、凋亡细胞数、Brdu/Nestin阳性细胞数比较差异均无统计学意义(P＞0.05). 结论 L-Ser能抑制SCI大鼠脊髓组织中神经细胞的凋亡,促进SCI大鼠脊髓组织eNSCs增殖.     

二甲胺四环素对大鼠脊髓损伤后Caspase-3表达及细胞凋亡的影响

[目的]探讨大鼠脊髓损伤后应用二甲胺四环素（minocyc line）对Caspase-3表达及细胞凋亡的影响。[方法]成年大鼠脊髓损伤后应用二甲胺四环素的治疗组（A组）和应用生理盐水对照组（B组），于损伤后不同时点取材，用HE染色观察损伤脊髓组织病理变化，用免疫组化染色检测Caspase-3表达阳性细胞，原位末端标记法（TUNEL法）标记凋亡细胞。[结果]HE染色镜检发现脊髓组织病理学改变A组明显轻于B组。A、B两组均发现凋亡细胞及Caspase-3表达，神经细胞凋亡指数及Caspase-3表达均B组〉A组（P〈0．01）。[结论]二甲胺四环素能抑制大鼠脊髓损伤后Caspase-3表达及细胞凋亡。     

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.     

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.     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

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.     

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.