自由描记肌电图监测腰椎手术中脊神经根功能的有效性分析

目的 :探讨单独应用自由描记肌电图监测腰椎手术中脊神经根功能的有效性。方法 :2014年10月~2015年10月共纳入246例腰椎病变在L2~S1节段之间且≤2个连续运动节段行单独自由描记肌电图监测的手术患者,男129例,女117例;年龄16~75岁,平均50.3±16.4岁。记录术中发生爆发性肌电活动、连续性肌电活动和自发性肌电活动的患者、相对应的手术操作、处理方法和转归。比较术前和术后神经功能状态,统计所有患者中真阳性、假阳性、真阴性和假阴性的病例,计算敏感性、特异性、阳性预测值和阴性预测值,分析自由描记肌电图监测的有效性。结果:术中监测时间80~140min,平均115.0±17.7min。所有患者中共有49例监测报警,爆发性肌电活动19例,连续性肌电活动27例,自发性肌电活动3例。其中,神经根牵拉过度28例,停止牵拉或减轻牵拉力度,肌电活动逐渐恢复正常;椎间融合器或植骨块植入挤压神经根8例,移除并改变植入角度避免挤压神经根,其中6例肌电活动逐渐恢复正常,2例转变为自发性肌电活动;椎弓根螺钉置入错位刺激神经根9例,移除并改变置钉轨道及角度,其中8例肌电活动逐渐恢复正常,1例右侧L5神经根支配肌肉仍有连续性肌电活动,术后右侧足背伸肌力减弱;4例患者探查未见刺激或损伤因素,肌电活动持续至手术结束,其中1例右侧S1神经根功能受损,术后右侧足底麻木;其余47例患者术后未出现神经功能受损。所有患者中197例未报警,术后1例左侧L5神经根功能受损,左侧胫前肌和背伸肌肌力0级。在阳性患者中,真阳性46例,其中2例术后神经功能受损;假阳性3例,阳性预测值为93.88%。在阴性患者中,真阴性196例,假阴性1例且术后神经功能受损,阴性预测值为99.49%。自由描记肌电图监测的敏感性为97.87%,特异性为98.49%。结论:应用自由描记肌电图监测L2~S1水平的手术可以减少神经根相关损伤,因其有较好的敏感性和特异性,可以对神经根功能的瞬间改变做出及时反馈,可作为腰椎手术中较为有效的神经监测方法。     

机器人辅助L4、L5椎弓根螺钉内固定术治疗腰椎滑脱症的学习曲线研究

目的研究机器人辅助L4、L5椎弓根螺钉内固定术治疗腰椎滑脱症的学习曲线及其拐点。方法回顾性分析2016年1月至2020年12月采用机器人辅助L4、L5椎弓根螺钉内固定术治疗43例腰椎滑脱症患者资料, 男19例、女24例;年龄59(48, 66)岁;按Meyerding分类, Ⅰ度滑脱23例, Ⅱ度滑脱18例, Ⅲ度滑脱2例。测量螺钉置入精度和螺钉准确性分级, 记录患者手术时间、术中出血量、术中透视次数、术后并发症、术后住院时间等信息。采用累计求和法绘制学习曲线, 根据形态将学习曲线分为前期和后期。对比学习前期和学习后期指标差异, 采用t检验、Wilcoxon秩和检验进行统计学分析。结果 43例腰椎滑脱症患者均顺利完成手术, 置入L4椎弓根螺钉60枚、L5椎弓根螺钉70枚。L4椎弓根螺钉置入精度在第23枚开始提高, L5椎弓根螺钉置入精度在第20枚开始提高。以第23枚椎弓根螺钉(第14例患者)分割学习曲线为前期和后期, 学习前期组与后期组在手术时间[(225.0±74.0)minvs.(207.0±81.2)min, t=0.65, P=0.521]、术中出血量[200(75, 500)...     

自由描记肌电图应用于腰椎手术中神经根监测的临床价值

目的探讨腰椎手术中应用自由描记肌电图(free-run electromyography,F-EMG)进行神经根监测的临床价值。方法自2015-11-2016-11,在132例腰椎手术中应用F-EMG进行实时监测,包括后路病灶清除、融合内固定术9例,后路减压融合内固定术106例,后路椎弓根钉内固定手术17例。对患者术中F-EMG表现情况及术后转归进行统计分析。结果 (1)132例中,共发生F-EMG报警28例,其中连续性肌电活动17例,爆发性肌电活动9例,自发性肌电活动2例;探明术中F-EMG异常原因有25例,均予以调整手术操作;未探明原因3例,其中2例为假阳性。未发生F-EMG报警104例,其中1例术后发生神经损伤(为假阴性)。(2)经证实,F-EMG术中监测的真阳性26例,假阳性2例;真阴性103例,假阴性1例。其敏感度为96.3%,特异度为98.1%,阳性预测值为92.9%,阴性预测值为99.0%。结论腰椎手术中予以F-EMG监测,具有较高的敏感度和特异度,起到可靠的预警作用,降低了神经根损伤的发生率,可作为一项较佳的腰椎手术配备方案予以考虑。     

神经电生理监测技术在胸腰椎骨折微创椎弓根螺钉置入术中的应用

目的探讨神经电生理监测技术在脊柱微创椎弓根置钉术中的应用价值。方法回顾分析2011年2月~2014年2月浙江省丽水市人民医院骨科收治的胸腰椎爆裂性骨折并行胸腰椎椎弓根置钉术患者资料52例,在经皮置钉过程中实时自发肌电(spontaneous electromyography,s EMG)和触发肌电(triggered electromyography,t EMG)监测、体感诱发电位(somatosensory evoked potential,SEP)检测。随访患者术后临床神经功能及置钉椎体薄层CT。结果术后9例患者SEP波幅较术前波幅升高,提示症状可能较术前改善,术后随访证实麻木感较术前改善。术中抓获暴发肌电3例,确认钉道破壁。222枚螺钉置入中,经CT提示有21枚螺钉穿破椎弓根,t EMG阳性23例,假阳性2例,并且螺钉破壁后位置与t EMG阈值无明显关联。按美国脊髓损伤学会(America spinal injury association,ASIA)分级随访患者神经功能,术前A级2例、B级3例、C级8例、D级30例、E级9例;末次随访A级1例、B级1例、C级2例、D级17例、E级31例,差异具有统计学意义(P0.05)。结论 EMG和SEP有各自的作用,联合监测具有互补作用,为指导脊柱椎弓根镙钉置入术的进程和提高手术安全性起到一定作用。     

骨科手术导航系统在椎弓根螺钉固定术中的应用

目的: 探讨骨科导航系统在脊柱椎弓根螺钉固定术的应用价值。方法: 同期行椎弓根螺钉固定术患者 44例 (男 26例,女 18例, 共 230枚椎弓根螺钉), 其中应用骨科手术导航系统及未应用该系统各 22例, 术后均进行置入螺钉节段的X线平片确定螺钉置入情况。结果: 应用骨科手术导航系统置入椎弓根螺钉无 1例出现早期并发症, 107 /116枚螺钉置入位置准确, 与对照组相比有显著性差异 (X2 =9. 17,P<0. 01)。结论: 应用骨科手术导航系统可保证螺钉置入位置的准确性, 降低手术相关并发症及避免放射线损害, 特别是对于椎弓根变异如脊柱侧凸、后凸畸形及严重脊柱退变有明显优越性。     

CT辅助斜位透视对L_5经皮椎弓根螺钉置入准确性的影响

目的回顾性研究术前CT扫描辅助斜位透视对L_5经皮椎弓根螺钉置入准确性的影响。方法回顾性分析2014年1月至2016年1月,在本院行腰椎经椎间孔椎间植骨融合术(minimally invasive surgery-transforaminal lumbar interbody fusion,MIS-TLIF)的116例患者临床资料。依据手术方式以及透视方法不同分为2组。A组66例为常规正侧位透视组。B组50例为术前CT辅助斜位透视组。依据椎弓根外侧切线与横突位置关系对椎弓根形态进行分类。比较组间螺钉位置、误置钉率、神经损害情况以及透视时间差异。同时,分析不同椎弓根形态对于螺钉置入准确性的影响。结果总计置入232枚椎弓根螺钉。A组132枚螺钉中80枚为0级,4枚螺钉为3级,其中外侧穿透2例,内侧穿透合并神经根症状2例,均进行开放性翻修并行神经根减压。B组50例采用斜位透视置钉患者中0级螺钉为74枚,3级螺钉为0枚。组间螺钉置入准确性比较,差异具有统计学意义(P=0.020)。透视时间比较,A组为(1.2±0.3)min,B组为(2.7±0.3)min,组间比较差异具有统计学意义(P=0.017)。对于L型椎弓根,两种透视方式准确性比较差异无统计学意义。S型椎弓根患者,使用斜位透视法准确性更高(P=0.001)。结论使用常规正侧位透视法进行L_5经皮椎弓根螺钉置入,存在较高的椎弓根螺钉穿破危险,尤其是S型椎弓根患者。参考术前CT的斜位透视法可以有效减小经皮椎弓根螺钉误置可能性,但透视时间会增加。     

直视下胸腰椎椎弓根螺钉旋转置入法临床应用

目的 研究直视下胸腰椎椎弓根螺钉旋转置入法的成功率、安全性及可操作性方面的应用价值.方法 采用后路切口直视下旋转置入法治疗胸腰椎骨折41例,置钉166枚.结果 166枚椎弓根螺钉置入均获成功,大部分椎弓根螺钉平行了椎体的上下终板,仪有7例椎弓根螺钉与椎体的上下终板轻度成角(5°～10°),符合置钉要求,1例其中1枚螺钉置入位置偏下,术后轻度神经根刺激症状,术后四周症状完全消失.结论 直视下胸腰椎椎弓根螺钉旋转置入法更准确可靠,可有效防止硬膜及神经根的损伤.     

术前CT引导胸腰椎椎弓根螺钉置入改良技术

目的:探讨总结以术前CT扫描椎弓根轴心来获得螺钉置入解剖参数引导胸腰段椎弓根螺钉置入的改良方法。方法:使用改良置钉技术对56例脊柱损伤患者置入胸腰椎弓根螺钉242枚,其中男32例,女24例;年龄21～69岁,平均43岁。以术前CT扫描确定椎弓根轴心线,轴心线附近的解剖标志为参照确定螺钉入点,内聚E角、螺钉长度、直径均可在CT椎弓根轴心片上读出,而矢状F角可由X线侧位片上读出或观察脊突线得出。结果:242枚螺钉术后均拍摄椎弓根CT片复查,238枚螺钉完全置入椎弓根内,仅4枚有穿破椎弓根皮质,失误率1.65%,但穿破较小,均无神经根症状。结论:术前CT扫描椎弓根引导胸腰椎椎弓根螺钉的置入是一个较好的改良方法,能有效降低不良置钉率。     

多层螺旋CT三维重建技术在胸腰椎骨折经椎弓根螺钉内固定术中的应用价值

目的:探讨多层螺旋CT(MSCT)三维重建技术在胸腰椎骨折患者经椎弓根螺钉内固定术中的应用价值。方法:2007年1月~2008年12月,78例胸腰椎骨折患者在我院行椎弓根螺钉内固定术,其中38例使用传统置钉法(Weinstein法或AO法)进行椎弓根螺钉置入(A组),40例采用MSCT三维重建设计钉道的置钉方法进行螺钉置入(B组),术后两组均复查胸腰椎正、侧位X线片和CT了解置入螺钉位置情况,应用Lonstein等的方法评判置钉准确率。结果:78例患者共置入椎弓根螺钉436枚,A组38例共置入212枚,12例32枚螺钉穿破椎弓根皮质,其中穿破椎弓根内外皮质21枚,穿破椎弓根上下皮质11枚,置钉准确率84.91%;B组40例共置入224枚,5例6枚螺钉穿破椎弓根皮质,其中穿破椎弓根内外皮质4枚,穿破椎弓根上下皮质2枚,置钉准确率97.33%。两组置钉准确率有统计学差异(P<0.05)。结论:胸腰椎骨折患者行椎弓根螺钉内固定时应用MSCT三维重建设计钉道的置钉方法较传统置钉方法成功率高。     

颈椎椎弓根螺钉误置的临床特征分析

目的:观察颈椎椎弓根置钉的准确性,分析螺钉误置的临床特征。方法:32例施行颈椎椎弓根置钉手术患者,男22例,女10例;年龄25~74岁(51.5±13.6岁)。颈椎骨折/脱位16例,颈椎后纵韧带骨化8例,颈椎多节段椎间盘突出1例,颈椎管内肿瘤7例(神经鞘瘤3例,脊膜瘤3例,室管膜瘤1例)。术前进行颈椎CT三维重建,确定椎弓根螺钉的进钉点,并测量椎弓根的内倾角、矢状面角度及直径、长度等参数;术中在C型臂X线机透视辅助下置入椎弓根螺钉;术后复查颈椎CT观察椎弓根螺钉位置,按照Lee等的方法判断椎弓根螺钉位置准确性:0级,螺钉未穿破椎弓根;1级,螺钉穿破椎弓根25%的螺钉直径;2级,螺钉穿破椎弓根25%,但50%的螺钉直径;3级,螺钉穿破椎弓根50%的螺钉直径。2级和3级判为螺钉误置,分析椎弓根螺钉误置的特点;观察血管神经损伤等并发症情况。结果:32例患者中因术中置钉困难更改为侧块螺钉3枚,改为寰椎椎板钩1枚,共置入颈椎椎弓根螺钉147枚(上颈椎40枚,中下颈椎107枚),椎弓根螺钉位置0级53枚,1级67枚,2级17枚(上颈椎2枚,下颈椎15枚),3级10枚(上颈椎1枚,下颈椎9枚)。椎弓根螺钉总误置率为18.3%(2级+3级);外侧壁穿破17枚,下壁5枚,上壁4枚,内侧壁1枚。上颈椎椎弓根螺钉的误置率(7.5%)显著低于中下颈椎(22.4%)(P0.05);椎弓根外侧壁穿破率(11.5%)高于上壁(2.7%)、下壁(3.4%,)及内侧壁(0.7%)(P均0.01)。5例患者6枚螺钉术中椎弓根钉道攻丝后活动性出血,予骨蜡封堵及置入螺钉后即止血,无血肿或脑缺血梗死并发症。3例患者术后出现上肢神经根刺激症状,予颈椎制动、神经营养治疗,分别于术后1个月、3个月、4个月好转。结论:颈椎椎弓根螺钉误置率较高,但相关并发症较少;穿破椎弓根外侧壁多于内侧壁、上壁或下壁;中下颈椎椎弓根螺钉的误置率高于上颈椎。     

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 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.     

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.