不同剂量氯胺酮对老年大鼠认知功能的影响

目的 探讨腹腔注射不同剂量氯胺酮对老年大鼠认知功能的影响.方法 老年SD大鼠40只,15月龄,体重470～570 g,雌雄各半,随机分为4组(n=10),对照组(C组)腹腔注射生理盐水2 ml,K1组、K2组和K3组分别腹腔注射氯胺酮10、20和100 mg/kg(溶于2 ml生理盐水),连续3 d.于停药后1 d(TI)、2 d(T2)、3 d(T3)行水迷宫实验,记录潜伏期及游泳路程.末次水迷宫测试结束后1 h处死大鼠,采用RT-PCR法测定海马N-甲基-D-天门冬氨酸(NMDA)受体亚基NR1 mRNA和NR2BmRNA的表达,免疫组织化学法测定海马NR1和NB2B蛋白的表达.结果 与T1时比较,C组和K2组T2,3时、K1,3组T3时潜伏期缩短,C组T2,3时、K1,2组T3时游泳路程缩短(P＜0.05);与C组比较,K3组T2,3时潜伏期和游泳路程延长,K1组NR2B蛋白表达上调,K3组NR2B mRNA及蛋白表达下调(P＜0.05);各组NR1 mRNA及蛋白表达差异无统计学意义(P＞0.05).结论 亚麻醉剂量氯胺酮对老年大鼠认知功能无明显影响,而麻醉剂量氯胺酮可致老年大鼠认知功能减退,其机制可能与含NR2B亚基的NMDA受体表达下调有关.     

RO20-1724对氯胺酮重复麻醉致未成年大鼠认知功能障碍的影响

目的 评价RO20-1724对氯胺酮重复麻醉致未成年大鼠认知功能障碍的影响.方法 健康SD大鼠48只,21日龄,雌雄不拘,体重45～55 g,采用随机数字表法,将其分为4组(n=12):对照组(C组)、氯胺酮组(K组)、氯胺酮+ RO20-1724组(K+R组)和氯胺酮+无水乙醇组(K+A组).K组腹腔注射氯胺酮70 mg/kg,1次/d,连续7d;K+R组和K+A组腹腔注射氯胺酮70 mg/kg,30 min后分别腹腔注射RO20-1724 0.5 mg/kg或等容量无水乙醇,1次/d,连续7d.C组腹腔注射等容量生理盐水,1次/d,连续7d.采用Morris水迷宫实验测定认知功能,记录逃避潜伏期和穿越原平台次数.Morris水迷宫实验结束当日,每组处死6只大鼠,取海马组织,电镜下观察超微结构.Morris水迷宫实验结束当日,每组处死6只大鼠,取海马组织,测定海马磷酸化环腺苷酸应答元件结合蛋白(p-CREB)表达.结果 与C组比较,K组和K+A组第3天和第4天时逃避潜伏期延长,穿越原平台次数减少,海马组织p-CREB表达下调(P＜0.05),K+R组逃避潜伏期、穿越原平台次数和p-CREB表达差异无统计学意义(P＞0.05);与K组比较,K+R组第3天和第4天时逃避潜伏期缩短,穿越原平台次数增多,海马组织p-CREB表达上调(P＜0.05),病理学损伤减轻,K+A组逃避潜伏期、穿越原平台次数和p-CREB表达差异无统计学意义(P＞0.05).结论 RO20-1724可改善氯胺酮重复麻醉致未成年大鼠认知功能障碍,其机制与上调海马p-CREB的表达.     

异丙酚对氯胺酮致老龄大鼠认知功能障碍的影响

目的 探讨异丙酚对氯胺酮致老龄大鼠认知功能障碍的影响.方法 健康雄性SD老龄大鼠32只,月龄18～24月龄,体重380～470 g,随机分为4组(n=8):对照组(C组)、异丙酚组(P组)、氯胺酮组(K组)和异丙酚+氯胺酮组(PK组).P组静脉输注异丙酚30 mg·kg-1·h-1,K组静脉输注氯胺酮40 mg·kg-1·b-1,PK组静脉输注异丙酚30 mg·kg-1·h-1+氯胺酮40 mg·kg-1·h-1,C组给予等容量生理盐水,每天2 h,连续7 d.给药结束后测定大鼠认知功能,记录逃避潜伏期和穿越平台次数.认知功能测试完毕后,处死大鼠,取海马组织,检测CA1区神经元凋亡情况,计算神经元凋亡率;测定CA1区caspase-3的表达水平.结果 与C组比较,P组逃避潜伏期、穿越平台次数、海马CA1区神经元凋亡率和caspase-3表达差异无统计学意义(P＞0.05),K组和PK组逃避潜伏期延长,穿越平台次数减少,海马CA1区神经元凋亡率升高,caspase-3表达上调(P＜0.05);与K组比较,PK组逃避潜伏期缩短,穿越平台次数增加,海马CA1区神经元凋亡率降低,caspase-3表达下调(P＜0.05).结论 异丙酚可减轻氯胺酮致老龄大鼠认知功能障碍,其机制可能与异丙酚可在一定程度上抑制氯胺酮所致caspase-3表达上调,从而抑制氯胺酮诱发的神经元凋亡有关.     

RO20-1724对氯胺酮麻醉后未成年大鼠认知功能的影响

目的 探讨RO20-1724对氯胺酮麻醉后未成年大鼠认知功能的影响.方法 SD大鼠96只,雌雄各半,21日龄,体重45～55 g,采用随机数字表法,将大鼠随机分为8组(n=12):对照组(C组)、氯胺酮组(K组)、氯胺酮+生理盐水组(K+N组)、氯胺酮+无水乙醇组(K+A组)、氯胺酮+不同剂量RO20-1724组(K+R1～4组).K组、K+N组、K+A组和K+R1～4组腹腔注射氯胺酮70 mg/kg,30 min后K+N组、K+A组和K+R1～4组分别腹腔注射生理盐水2 ml、无水乙醇8 μl(生理盐水稀释到2 ml)和RO20-1724 0.25、0.50、0.75、1.00 mg/kg(先溶于8μl无水乙醇中,再用生理盐水稀释至2ml).给药结束后24h时,每组取6只大鼠,进行Morris水迷宫实验测试认知功能.给药结束后48 h时,每组处死6只大鼠,采用Western blot法检测海马和大脑皮层环磷酸腺苷反应元件结合蛋白(CREB)和磷酸化CREB (p-CREB)的表达.结果 与C组比较,K组、K+N组、K+A组、K+R1组和K+R2组给药后2～4d时逃避潜伏期延长,穿越平台次数减少,海马和皮层CREB和p-CREB表达下调(P＜0.05)；与K组比较,K+R3组和K+R4组给药后2～4d时逃避潜伏期缩短,穿越平台次数增多,海马和皮层CREB和p-CREB表达上调(P＜0.05)；与K+R1组和K+R组比较,K+R3组和K+R4组给药后2～4d时逃避潜伏期缩短,穿越平台次数增多,海马和皮层CREB和p-CREB表达上调(P＜0.05)；K+R1组与K+R2组间、K+R3组与K+R4组间上述各指标比较差异无统计学意义(P＞0.05).结论 RO20-1724 0.75 ～ 1.00 mg/kg可通过上调海马和大脑皮层CREB和p-CREB的表达,改善氯胺酮致未成年大鼠认知功能障碍.     

孕早期氯胺酮麻醉对子代大鼠海马c-fos mRNA和c-jun mRNA表达的影响

目的 探讨孕早期氯胺酮麻醉对子代大鼠海马c-fos mRNA和c-jun mRNA表达的影响.方法 孕5～13 d的SD大鼠30只,体重250～300 g,随机分为2组(n=15):对照组(C组)和氯胺酮组(K组).K组经尾静脉注射氯胺酮20 mg/kg,随后以130 mg·kg-1·h-1的速率静脉输注2 h;C组以等量生理盐水替代氯胺酮.子代大鼠于出生后20和30 d时测定认知功能,取海马组织,测定c-fosmRNA和c-jun mRNA表达水平并观察超微结构.结果 与C组比较,K组子代大鼠出生后30 d时认知功能测定第2天逃避潜伏期延长(P＜0.05),海马c-fos mRNA和c-jun mRNA的表达水平差异无统计学意义,出生后20 d上述指标差异无统计学意义(P＞0.05).K组海马神经元发生损伤.结论 孕早期氯胺酮麻醉抑制子代大鼠认知功能的机制与海马神经元受损有关,但与海马c-fos mRNA和c-jun mRNA表达无关.     

异丙酚对抑郁大鼠电休克治疗后海马神经元环氧化酶-2表达的影响

目的 探讨异丙酚对抑郁大鼠电休克治疗后海马神经元环氧化酶-2(COX-2)表达的影响.方法 健康成年雄性SD大鼠50只,2～3月龄,体重200 ～ 250 g,采用连续不可预见性慢性应激制备抑郁模型,造模成功的40只大鼠,采用随机数字表法,将其随机分为4组(n=10):抑郁组(D组)、异丙酚组(P组)、电休克组(E组)和异丙酚联合电休克组(PE组),另取10只大鼠作为正常对照组(C组).P组和PE组腹腔注射异丙酚80 mg/kg,其他3组给予等容量生理盐水,E组和PE组分别于给予生理盐水8 ml/kg或异丙酚后5 min时进行电休克治疗,1次/d,连续7d.分别于造模前、造模后和治疗结束后进行进行水迷宫实验,记录逃避潜伏期和目标象限游泳时间百分比.然后处死大鼠,取海马组织,检测COX-2表达.结果 与C组比较,D组、P组、E组和PE组造模后逃避潜伏期延长,目标象限游泳时间百分比降低,海马组织COX-2表达上调,D组、P组和E组治疗结束后逃避潜伏期延长,目标象限游泳时间百分比降低(P＜0.05);与D组比较,E组治疗结束后逃避潜伏期延长,海马组织COX-2表达上调,PE组逃避潜伏期缩短,目标象限游泳时间百分比升高(P＜0.05);与E组比较,PE组治疗结束后逃避潜伏期缩短,目标象限游泳时间百分比升高,海马组织COX-2表达下调(P＜0.05).结论 异丙酚可改善抑郁大鼠电休克治疗后认知功能,其机制与下调海马神经元COX-2表达有关.     

氯胺酮麻醉及脾切除术对幼年大鼠学习记忆的影响

目的观察氯胺酮麻醉及脾切除术对幼年大鼠学习记忆的影响。方法健康幼年雄性SD大鼠30只,15日龄,体重29~31g,随机分为三组:生理盐水组(S组)、氯胺酮组(K组)、氯胺酮+脾切除组(KS组),三组大鼠腹腔分别给予等容量生理盐水0.3 ml、氯胺酮100 mg/kg(10mg/ml)、氯胺酮100mg/kg(10mg/ml),KS组大鼠氯胺酮麻醉后行脾切除。2周后三组大鼠进行Morris水迷宫实验,记录逃避潜伏期、Ⅱ象限穿越次数及Ⅱ象限游泳时间。水迷宫实验结束后杀死大鼠,采用ELISA法检测大鼠海马组织谷氨酸(Glu)和γ-氨基丁酸(GABA)含量。结果与S组比较,K组前3d和KS组前4d逃避潜伏期明显延长(P0.01),K组和KS组Ⅱ象限穿越次数明显减少,Ⅱ象限游泳时间明显缩短(P0.05);与K组比较,KS组逃避潜伏期明显延长,Ⅱ象限穿越次数明显减少,Ⅱ象限游泳时间明显缩短(P0.01)。与S组比较,K组和KS组Glu含量明显降低,Glu/GABA明显减小(P0.05),KS组GABA含量明显升高(P0.05);与K组比较,KS组Glu含量明显降低,Glu/GABA明显减小(P0.05)。结论氯胺酮麻醉及脾切除均能损伤幼年大鼠的学习记忆功能,且其记忆功能受损与海马区Glu含量及Glu/GABA下调有关。氯胺酮对幼年大鼠学习能力的损害只是暂时的,脾切除能延长并进一步损害幼年大鼠的学习能力。     

氯胺酮对新生大鼠海马CREB磷酸化水平的影响

目的 探讨氯胺酮对新生大鼠海马环磷腺苷反应元件结合蛋白(CREB)磷酸化水平的影响.方法 SD大鼠75只,日龄7 d,雌雄不拘,随机分为对照组(C组)、氯胺酮10 mg/kg组(K1组)和氯胺酮20 mg/kg组(K2组),每组25只.K1组和K2组分别皮下注射氯胺酮10、20 mg/kg,C组注射等容量生理盐水,每间隔90 min注射1次,共注射7次.于首次注射后24 h时断头取脑,分离海马,采用TUNEL法检测凋亡神经元,计算凋亡指数;免疫荧光双标法检测p-CREB表达水平;RT-PCR法半定量检测CREB下游基因BDNF mRNA及Bcl-2 mRNA表达水平;于首次注射后6周时采用Morris水迷宫实验测定各组大鼠认知功能.结果 与C组相比,K1组和K2组大鼠海马神经元凋亡指数升高,p-CREB、BDNF mRNA及Bcl-2 mRNA表达下调(P<0.05);与K1组相比,K2组大鼠海马神经元凋亡指数升高,p-CREB、BDNF mRNA及Bcl-2 mRNA表达下调(P<0.05);与C组和K1组相比,K2组逃避潜伏期延长(P<0.05).结论 氯胺酮10、20 mg/kg均可诱导发育期大鼠海马神经元凋亡,而氯胺酮20 mg/kg可导致大鼠发育成熟后认知功能降低,可能与其抑制CREB磷酸化后BDNF及Bcl-2表达下调,导致神经元凋亡,影响大鼠神经系统发育有关.     

氯胺酮对新生大鼠海马CREB磷酸化水平的影响

目的 探讨氯胺酮对新生大鼠海马环磷腺苷反应元件结合蛋白(CREB)磷酸化水平的影响.方法 SD大鼠75只,日龄7 d,雌雄不拘,随机分为对照组(C组)、氯胺酮10 mg/kg组(K1组)和氯胺酮20 mg/kg组(K2组),每组25只.K1组和K2组分别皮下注射氯胺酮10、20 mg/kg,C组注射等容量生理盐水,每间隔90 min注射1次,共注射7次.于首次注射后24 h时断头取脑,分离海马,采用TUNEL法检测凋亡神经元,计算凋亡指数;免疫荧光双标法检测p-CREB表达水平;RT-PCR法半定量检测CREB下游基因BDNF mRNA及Bcl-2 mRNA表达水平;于首次注射后6周时采用Morris水迷宫实验测定各组大鼠认知功能.结果 与C组相比,K1组和K2组大鼠海马神经元凋亡指数升高,p-CREB、BDNF mRNA及Bcl-2 mRNA表达下调(P<0.05);与K1组相比,K2组大鼠海马神经元凋亡指数升高,p-CREB、BDNF mRNA及Bcl-2 mRNA表达下调(P<0.05);与C组和K1组相比,K2组逃避潜伏期延长(P<0.05).结论 氯胺酮10、20 mg/kg均可诱导发育期大鼠海马神经元凋亡,而氯胺酮20 mg/kg可导致大鼠发育成熟后认知功能降低,可能与其抑制CREB磷酸化后BDNF及Bcl-2表达下调,导致神经元凋亡,影响大鼠神经系统发育有关.     

手术创伤对老龄大鼠海马CA3区突触结构的影响

目的 探讨手术创伤对老龄大鼠海马CA3区突触结构的影响.方法 健康SD大鼠56只,月龄18月,随机分为3组,对照组(C组,n=8)腹腔注射生理盐水0.8 ml/kg;麻醉组(A组,n=24)腹腔注射氯胺酮40 mg/kg;手术组(O组,n=24)腹腔注射氯胺酮40 mg/kg,翻正反射消失后行脾脏切除术.A组和O组于麻醉或术后1、3,7 d(T_(1～3))时取8只大鼠行Morris水迷宫实验测试认知功能,并测定海马CA3区突触结构各指标.结果 与C组和A组比较,O组T_(1,2)时通过原平台次数、突触数减少,突触间隙增宽,突触后膜致密物厚度变薄,突触活性带长度缩短,突触界面曲率减小(P<0.05或0.01).与C组比较,A组T_1时、O组T_(1,2)时潜伏期及游泳距离延长(P<0.01);与A组比较,O组T_(1,2)时潜伏期延长,T_2时游泳距离延长(P<0.05).结论 手术创伤导致老龄大鼠术后早期认知功能减退的机制与海马CA3区突触结构改变有关.     

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.     

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.