应用Sky bone expander system经皮椎体成型术的生物力学评价

目的应用Sky bone expander system在体外经皮椎体成型术治疗椎体压缩性骨折,观察并评价生物力学性能。方法选取8具尸体脊柱标本(T10～L2)并游离成40个椎体,测定骨密度后随机分为3组；Ⅰ组为空白对照组(n=20)；Ⅱ组为球囊经皮椎体成型术组即球囊组(n= 10)；Ⅲ组为应用Sky bone expander system经皮椎体成型术组即Sky组(n=10)。在C型臂X线机导引下对Ⅱ和Ⅲ组椎体经双侧椎弓根行充填PMMA。在万能材料试验机上将所有椎体前缘压缩至原来高度的50%,测得最大载荷及刚度；然后将Ⅰ组在随机分为ⅠA组和ⅠB组,分别用球囊和Sky bone expander system行椎体成型术,再次按前述加载方法将椎体前缘压缩至充填后高度得50%,测得高度、最大载荷及刚度变化。结果实验前各组骨密度(BMD)为(0．298～0．650)g/ cm~2,高度为(1．87～2．83)cm。实验后Ⅰ组椎体的最大载荷为(2 632．75±64．83)N,刚度为(602．70±30．24)N/mm；Ⅱ组椎体的最大载荷为(5 215．60±70．46)N,刚度为(1 012．32±92．45) N/mm；Ⅲ组椎体的最大载荷为(5 320．75±92．38)N,刚度为(980．40±73．63)N/mm；最大载荷方面：Ⅰ组与Ⅱ、Ⅲ、ⅠA和ⅠB组间差异有统计学意义(P＜0．05)。刚度方面：Ⅰ组与Ⅱ、Ⅲ、ⅠA和ⅠB组间差异有统计学意义(P＜0．05),Ⅱ、Ⅲ、ⅠA和ⅠB组间差异无统计学意义(P＞0．05)。结论Sky bone expander system可有效的恢复椎体的生物力学性能,可为临床提供一种新的经皮椎体成型术方法。     

氯胺酮对小儿术后镇痛中吗啡作用的影响

目的　研究氯胺酮在小儿术后硬膜外自控镇痛中对吗啡作用的影响。方法　全麻下择期腹部手术病儿 37例 ,病人随机分为三组。负荷量 :Ⅰ组 (n =13)吗啡 10 μg/kg +氯胺酮 0 1mg/kg ;Ⅱ组 (n =10 )吗啡 10 μg/kg ;Ⅲ组 (n =14)吗啡 2 0 μg/kg。维持量 :Ⅰ组吗啡 1μg·kg-1·h-1+氯胺酮 0 0 3mg·kg-1·h-1;Ⅱ组吗啡 1μg·kg-1·h-1;Ⅲ组吗啡 2 μg·kg-1·h-1。单次给药剂量 :同各组每小时持续量 ;锁定时间 10min。按预定 6个时点记录疼痛、镇静评分、维持期吗啡耗量及不良反应发生率。结果　疼痛评分 :Ⅰ、Ⅲ组均为 0 0 0± 0 0 0 ,明显优于Ⅱ组 0 12± 0 17(P <0 0 1)。吗啡维持量 :Ⅰ、Ⅱ、Ⅲ组分别为 :5 1 0± 3 3μg/kg、6 3 4± 18 0 μg/kg、117 6± 2 0 1μg/kg(P <0 0 1)。镇静评分及不良反应发生率均无显著性差异。结论　小儿术后硬膜外自控镇痛中 ,微量氯胺酮明显增强吗啡的镇痛作用 ,减少吗啡用量     

异丙酚与依托咪酯麻醉诱导中血皮质醇和血糖变化的临床研究

目的 :观察异丙酚与依托咪酯麻醉诱导过程中血糖和皮质醇的变化 ,以评价两药物对应激反应的抑制作用。方法 :40例ASAⅠ～Ⅱ级行腹腔镜下胆囊切除术患者 ,随机分为异丙酚组 (A组 ,n =2 0 )和依托咪酯组 (B组 ,n =2 0 )。麻醉诱导A组异丙酚 2mg/kg、B组依托咪酯 0 4mg/kg ,加用芬太尼 2 μg/kg、阿曲库铵 0 5mg/kg。结果 :(1)诱导后血糖A组由 4 5 9± 0 6 7mmol/L增至 4 93± 0 6 3mmol/L ;B组由 5 0 4± 0 5 0mmol/L增至 5 6 7± 0 80mmol/L(P <0 0 5 )。 (2 )血皮质醇A组由 13 6± 5 17μg/L降至 10 4± 5 5 6 μg/L ;B组由 12 3± 5 18μg/L降至 8 37±4 13μg/L(P <0 0 5 )。 (3)诱导后 5分钟 ,A组BP、HR均明显下降 (P <0 0 5 ) ;而B组则上升 (P <0 0 5 ) ,10分钟后恢复至诱导前水平。结论 :异丙酚与依托咪酯均能抑制麻醉插管时的应激反应 ,但异丙酚比依托咪酯更为有效     

丙泊酚和芬太尼复合麻醉应用于无痛结肠镜检查

目的　探讨丙泊酚复合小剂量芬太尼麻醉应用于无痛结肠镜检查的可行性及不良反应。方法　 2 80例ASAⅠ～Ⅲ级患者分为无痛肠镜组 (Ⅰ组 ,n =2 0 0 ) ,常规肠镜组 (Ⅱ组 ,n =80 )。Ⅰ组从静脉缓慢注入芬太尼 0 4 μg/kg和丙泊酚 0 5～ 2mg/kg ,直至患者睫毛反射消失即可插入肠镜 ;Ⅱ组按常规方法进行肠镜检查 ;专人评估患者的术中和术毕恢复情况及术后调查。结果　肠镜检查完成率Ⅰ组高于Ⅱ组 (10 0 % :92 6 0 % )。在检查 5min时Ⅰ组的SBP、MAP、HR比检查前明显下降 (P <0 0 5 ) ;Ⅱ组的SBP、MAP比检查前明显增加 (P <0 0 5 ) ,术毕均恢复至术前水平。患者术毕至清醒、计算能力恢复正常和离开观察室的时间分别为 (1 90± 1 4 0 )min、(4 30± 2 90 )min、(18 30± 5 6 0 )min ;Ⅰ组的患者、检查者、记录者满意度评分和再次检查接受率明显高于Ⅱ组 (P <0 0 5 )。结论　丙泊酚复合小剂量芬太尼麻醉实施无痛肠镜检查是安全可行的     

人肝癌细胞膜胰岛素受体的研究及临床意义

目的　研究临床上用胰岛素作为载体通过受体介导对肝癌进行靶向治疗的可行性及其临床价值。方法　以A14 12 5I 标记胰岛素 ,取人肝癌细胞及癌旁组织 ,制备细胞膜 ,测定细胞膜胰岛素受体密度并评价其受体结合活性。结果　A14 12 5I 胰岛素比放射性为 (46 1± 1 2 )TBq/mmol,放射化学纯度 >98% ;人肝癌及癌旁组织细胞膜胰岛素受体Bmax分别为 (1 9± 0 6 )pmol/mg蛋白及(1 4± 0 6 )pmol/mg蛋白 ,高亲和力Kd(解离常数值 )值为 (2 1± 0 6 )nmol及 (2 2± 0 8)nmol,低亲和力Kd值为 (2 5± 8)nmol及 (2 7± 8)nmol。人肝癌细胞膜胰岛素受体表达高于癌旁组织 (最大结合值Bmaxt=0 0 32 ,P <0 0 5 )。结论　A14 12 5I 胰岛素与人肝癌细胞膜胰岛素受体具有特异性的结合力     

地塞米松对中性粒细胞死亡过程的调控

目的　研究地塞米松对中性粒细胞死亡的调控 ,阐明地塞米松防治皮瓣缺血再灌注损伤的机理。方法　 5 0只大鼠等分成 5组。Ⅰ组 :正常皮瓣组 ;Ⅱ组 :阻断动脉 8h ,生理盐水对照组 ;Ⅲ组 :阻断静脉 8h ,生理盐水对照组 ;Ⅳ组阻断动脉 8h ,地塞米松 5mg kg组 ;Ⅴ组 :阻断静脉 8h ,地塞米松 5mg kg组。术后观测皮瓣成活面积 ,检测全血中中性粒细胞凋亡、坏死水平。光镜观察中性粒细胞凋亡及坏死形态 ,电镜观察吞噬细胞吞噬凋亡中性粒细胞形态。结果　Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ组的皮瓣成活面积分别是 ( 99 8± 2 5 ) %、( 18 8± 1 8) %、( 9 0± 0 8) %、( 98 2± 2 4) %、( 96 2± 2 2 ) %。中性粒细胞凋亡含量术后早期Ⅱ、Ⅲ组明显低于另外 3组 ,但第 6天则高于另外 3组。坏死水平术后Ⅱ、Ⅲ组高于另外 3组。皮瓣中吞噬细胞吞噬凋亡粒细胞的数量Ⅳ、Ⅴ组明显高于Ⅱ、Ⅲ组。结论　地塞米松防治皮瓣缺血再灌注损伤的原因在于调理了中性粒细胞凋亡水平 ,减少了其坏死数量 ,增加吞噬细胞吞噬凋亡中性粒细胞的水平。     

开颅术中过度通气对哌库溴铵时效的影响

目的 :研究过度通气对哌库溴铵时效的影响。方法 :选择无神经肌肉疾患 ,ASAⅠ～Ⅱ级择期神经外科手术患者 2 4例 ,随机分成对照组 (A组 ,n =12 )和过度通气组 (B组 ,n =12 ) ,术中控制呼吸 ,维持PaCO2 分别大于或小于 35mmHg。用加速度仪监测拇内收肌收缩反应。观察两组哌库溴铵 0 1mg/kg时效差异。结果 :A、B组起效时间分别为 3 2 1± 0 49分钟和 3 0 8± 0 2 3分钟 ,无显著性差异 ;临床时效分别为 10 4 6 7± 7 33分钟和 87 0 8± 5 45分钟 ,P <0 0 5 ;恢复指数分别为 2 6 2 5± 2 85分钟和 2 3 75± 2 73分钟 ,无显著性差异。结论 :过度通气可使哌库溴铵临床时效缩短 ,但起效时间和恢复指数无明显差异     

不同水平呼气末正压通气对头低位腹腔镜手术患者肺顺应性及肺氧合的影响

目的 观察不同呼气末正压通气(positive end-expiratory pressure,PEEP)对头低位腹腔镜手术患者的肺顺应性及肺氧合的影响,探讨在头低位腹腔镜手术施行PEEP的合适水平. 方法 选择ASA分级Ⅰ、Ⅱ级,择期行腹腔镜直结肠手术患者45例,根据随机数字表法分成3组(每组15例):Ⅰ组,PEEP=0;Ⅱ组,PEEP=4 cmH2O(1 cmH2O=0.098 kPa);Ⅲ组,PEEP=8 cmH2O.术中采用容量控制通气,维持PETCO2 35～45 mmHg(1 mmHg=0.133 kPa),记录麻醉诱导后即刻(T0)、手术开始后10 min(T1)、各组实施不同水平PEEP干预后30 min (T2)和60 min(T3)、手术结束拔管前10 min(T4)的PETCO2、肺动态顺应性(pulmonary dynamic compliance,Cdyn),并同时抽取动脉血和深静脉血行血气分析,计算死腔通气比(dead space ventilationratio,Vd/Vt)和肺内分流率(intrapulmonary shunt,Qs/Qt). 结果 3组患者一般资料、HR及MAP差异无统计学意义(P＞0.05).3组患者Cdyn在T1时较T0时均降低(P＜0.05),Ⅱ组和Ⅲ组在T2时上升,在T4时[Ⅱ组(50.9±9.8) ml/cmH2O,Ⅲ组(58.8±13.4) ml/cmH2O]高于T0时[Ⅱ组(47.6±10.6) ml/cmH2O,Ⅲ组(51.3±10.8) ml/cmH2O](P＜0.05),Ⅲ组在T2、T3时高于Ⅰ组[T2:Ⅲ组(42.8±9.9) ml/cmH2O,Ⅰ组(29.3±8.0) ml/cmH2O;T3:Ⅲ组(42.9±10.3) ml/cmH2O,Ⅰ组(29.3±8.6) m]/cmH2O] (P＜0.05).3组的Vd/Vt在T1时均增大(P＜0.05),Ⅰ组和Ⅲ组在T4时[Ⅰ组(21.5±7.6)％,Ⅲ组(24.2±6.8)％]高于T0时[Ⅰ组(9.5±5.8)％,Ⅲ组(10.7±5.2)％](P＜0.05),而Ⅱ组在T4时[(12.2±6.8)％]同T0时[(9.9±7.8)％]比较,差异无统计学意义(P＞0.05),且低于同一时点Ⅰ组和Ⅲ组(P＜0.05).Ⅱ组的Qs/Qt在T4时低于Ⅰ组[Ⅱ组(12.3±6.3)％,Ⅰ组(26.2±20.8)％](P＜0.05).中心静脉血氧分压(central venous partial pressure of oxygen,PvO2)3组均逐渐上升(P＜0.05).Ⅱ组在T4时PaO2和PvO2均高于其他两组(P＜0.05). 结论 PEEP有利于头低位腹腔镜手术患者的肺顺应性及肺氧合.4 cmH2O PEEP不仅能改善肺顺应性,更有利于降低Vd/Vt和Qs/Qt,增加肺氧合.     

缺血预处理对大鼠移植肝脏保存再灌注损伤的保护及机制探讨

目的探讨缺血预处理 (ischemicpreconditioning ,IP)对大鼠移植肝脏保存再灌注损伤的保护作用及机理。方法采用SD大鼠原位肝移植动物模型 ,12 8只大鼠随机分成A(对照组 )、B(IP组 )、C(腺苷 ,Ado组 )、D(NO合成抑制剂 ,NAME组 )组 ,每组 32只。其中各组的半数用于观察存活率 ,另一半用于移植肝脏再灌注 2h后取血及肝脏检测。结果IP组和Ado组的 1周存活率、血清NO水平及肝组织腺苷含量分别为 88% (7/ 8)和 88% (7/ 8) ,(33 0± 6 1) μmol/l和 (2 9 1± 6 5 ) μmol/l,(7 2± 1 8) μmol/g和 (5 7± 1 3) μmol/g ,均高于对照组的 38% (3/ 8) ,(15 4± 3 0 )mol/L和 (3 6 9±0 5 4 ) μmol/g (P <0 0 5 ) ,血清ALT及TNF含量分别为 (2 87± 82 )IU/L和 (35 7± 93)IU/L ,(1 15± 0 2 3)ng/ml和 (1 14± 0 2 7)ng/ml,均低于对照组的 (5 88± 5 8)IU/L及 (1 5 9± 0 35 )ng/ml(P <0 0 5 ) ,组织的病理学改变也轻于对照组 ;NAME组的 1周存活率、血清NO及ALT含量等分别为 2 5 % (2 / 8)、(13 74± 3 11) μmol/l及 (6 34± 6 5 )IU/L ,与对照组相近 (P >0 0 5 ) ,而肝组织腺苷含量为 (5 5 6± 1 19)μmol/g ,与对照组差异有显著意义 (P <0 0 5 )。 结论IP对大鼠移植肝脏的保存再灌注损伤具有保护     

美维库铵持续静滴与单次静注肌松效应及恢复过程的临床药效学观察

目的 :观察美维库铵持续静滴和单次静注肌松效应及术后恢复的临床药效学指标。方法 :6 0例ASA分级Ⅰ～Ⅱ级复合全麻患者随机分为四组 ,每组 15例。美维库铵 0 2 5mg/kg给药后行气管插管 ,Ⅰ、Ⅱ组以微量泵持续静滴美维库铵 ,Ⅲ、Ⅳ组单次静注美维库铵维持肌松。术后Ⅰ、Ⅲ组患者待肌松自主恢复 ,Ⅱ、Ⅳ组静注新斯的明5 0 μg/kg、阿托品 10 μg/kg拮抗。结果 :实验提示 0 2 5mg/kg的美维库铵剂量可于 2 4± 0 6分钟内产生满意的插管条件 ,优秀率 95 %以上。Ⅰ、Ⅱ、Ⅲ、Ⅳ组平均用药量分别为 4 7± 1 2、5 0± 1 9、5 2± 2 2和 4 9± 1 8μg·kg-1·min-1,持续静滴组与单次静注组用药量无显著性差异 (P >0 0 5 )。Ⅰ、Ⅲ组恢复指数分别为 8 1± 2 3分钟和 8 7± 2 2分钟 (P >0 0 5 )。Ⅱ、Ⅳ组的恢复指数亦无明显差异 ,但比自然恢复组约缩短 2分钟左右。结论 :美维库铵持续静滴与单次静注用药量无明显差异 ,持续静滴可获得较好的肌松效果。术后使用新斯的明拮抗虽可加快肌缩力的恢复 ,但因其短效作用 ,故术后无需常规拮抗。     

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.     

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.