胸椎椎体后缘骨内软骨结节的发生特点与手术治疗

目的探讨胸椎椎体后缘骨内软骨结节的特点以及软骨结节切除术与改良全脊髓减压术的疗效。方法1978年5月至2005年5月,手术治疗胸椎椎体后缘骨内软骨结节32例,男18例,女14例;年龄23～70岁,平均47.8岁。X线片可见损伤终板后上或后下缘的骨赘、游离骨块、缺损;CT轴位片可见突向椎管的环形或块状骨化影,其内为低密度区;MRI可见脊髓受压,但无法分辨骨性终板与软骨终板。前20年的6例分别采用传统全椎板减压术、侧前方减压术、整块半关节突全椎板减压术治疗各2例;后6年采用软骨结节切除术治疗21例、改良全脊髓减压术治疗5例。结果32例中31例发生于胸腰段、1例位于T8。共发生胸椎椎体后缘骨内软骨结节37处,椎体上终板30处、下终板7处;单一椎体终板发病者27例、相邻椎体上下终板同时发病者4例、跳跃性两处发病者1例。32例中合并胸椎黄韧带骨化者16例,7例与胸椎椎体后缘骨内软骨结节发生于同一椎间、9例发生于与软骨结节上下相邻及其以远椎间。黄韧带骨化按CT分型,棘状型与结节型11例、板块型与隆突型5例。随访26例,随访时间1～27年,平均3.8年。按Otanni分级方法,优22例(84.6%)、良3例(11.5%)、可1例(3.9%)。结论胸椎椎体后缘骨内软骨结节多发于胸腰段椎体的上终板,且常常合并胸椎黄韧带骨化;软骨结节切除术与改良全脊髓减压术是治疗该病的安全、有效术式。     

前方入路手术治疗上胸椎转移瘤

目的:探讨前方入路行上胸椎肿瘤切除、椎体重建、钛板内固定的技术及方法,分析手术治疗效果及相关并发症。方法:2004年6月~2011年7月我科收治上胸椎(T1~T4)转移瘤患者17例,其中男6例,女11例,年龄55,1±7.3岁(47~68岁)。术前神经功能按Frankel分级:B级3例,C级4例,D级8例,E级2例。肿瘤位置:T1 7例,T2 5例,T3 3例,T4 2例。按Tokuhashi脊柱转移瘤评分系统评分为9~12分;根据WBB分区理论肿瘤病灶位于4~9区。对于T1椎体病灶患者采用低位下颈椎前方入路;对于T2~T4椎体病灶患者采用前方劈开胸骨经头臂干外侧间隙入路。结果:所有患者均能很好耐受手术,低位下颈椎前方入路手术时间为94.1士5.0min(90~102min),出血量为186.6±100.2ml(100~400ml);前方劈开胸骨经头臂干外侧间隙入路手术时间为121.0±165(100~150min),出血量为352.0±134.4ml(220~600ml)。术后病理学检查:6例来源于肺癌,5例来源于乳腺癌,2例来源于甲状腺癌,2例来源于胃肠道癌,2例来源不明。术后2例前方劈开胸骨经头臂干外侧间隙入路手术患者出现肺部感染、肺不张,经对症治疗后治愈。3例(其中1例为低位下颈椎前方入路手术患者)出现喉返神经牵拉伤致一过性声音嘶哑,术后1个月内声音恢复正常。随访19.7±9.8个月(6~48个月),9例患者神经功能有不同程度改善,其中3例Frankel分级B级患者2例改善为E级,1例改善为D级;4例C级2例改善到E级,2例改善到D级;2例D级患者改善到E级。5例患者在术后6~14个月因多处转移、全身衰竭死亡。结论:前方入路是治疗上胸椎转移瘤可供选择的有效入路,该入路可以充分显露前方椎体病变,有效切除病灶,彻底解除来自脊髓前方的压迫,改善患者症状。     

胸椎管狭窄症术后并发症的防治

目的探讨胸椎管狭窄症术后并发症的发生与防治。方法1985年1月至2005年1月手术治疗283例胸椎管狭窄症患者。胸椎黄韧带骨化症123例、胸椎后纵韧带骨化症73例、胸椎间盘突出症54例、弥漫性原发性骨肥厚症19例、椎体后缘骨内软骨结节14例。1996年以前均采用后入路,枪式咬骨钳切除椎板,咬除骨化的黄韧带或关节突的内1/2,为原始方法;1996年后,椎间盘突出或合并后纵韧带骨化、椎体后缘骨内软骨结节者采用经胸腔入路。黄韧带骨化、弥漫性原发性骨肥厚,采用后入路,应用磨钻加"揭盖法"切除椎板,在神经剥离子的保护下,应用骨凿切除关节突的内1/2,为改进方法。分别观察两组围手术期、中远期和供骨区并发症发生情况,并进行对比。结果随访254例,随访时间1~19年,平均6年2个月。并发症发生率42.1%,原始方法(65.2%)明显高于改进方法(23.2%)。各种并发症中脊髓损伤和硬脊膜损伤的发生率两组差异有统计学意义(P<0.05)。结论脊髓损伤导致症状加重是灾难性的并发症。采用改进方法手术治疗胸椎管狭窄症可减少并发症的发生。     

肩胛下经胸入路切除及重建治疗上胸椎肿瘤

目的 探讨肩胛下经胸入路切除及重建上胸椎肿瘤的技术及方法 ,分析患者的手术治疗效果及手术相关并发症.方法 收集自2003年2月至2005年2月北京大学人民医院骨肿瘤科手术治疗的上胸椎椎体(T1-4)肿瘤患者21例,转移癌11例,嗜酸性肉芽肿2例,骨肉瘤1例,尤文肉瘤2例,软骨肉瘤2例.骨巨细胞瘤2例,淋巴瘤1例.采用经肩胛下胸腔入路行上胸椎肿瘤切除、脊髓减压,结合人工椎体植入或者单纯植骨、前路侧方内固定术.结果 所有患者术后疼痛均得到缓解.3例出现截瘫症状的患者术后Frankel分级由A级改善为D级,2例患者下肢感觉肌力恢复正常.术后2例患者出现肺部炎症、肺不张,1例患者出现脑脊液胸腔漏,1例患者术后出现胸主动脉破损出血.术后随访11～58个月,其中9例患者死亡,包括7例转移癌、1例尤文肉瘤、1例骨肉瘤患者.结论 经肩胛下胸腔入路切除颈胸段及上胸椎肿瘤是处理上胸椎病变的理想入路,尤其是对于累及椎体及一侧椎弓根的患者尤为适宜.该手术方式可以充分显露前方椎体的病变,可以有效地解除来自前方椎体的脊髓压迫.     

经肋椎关节手术入路治疗胸椎多椎体结核的临床研究

目的 探讨后路经肋椎关节入路病灶清除、内固定、植骨融合治疗胸椎多椎体结核的临床效果.方法 回顾分析2005年7月~2011年7月,采用后路经肋椎关节病灶清除、内固定、植骨融合手术治疗的胸椎多椎体结核患者43例,术前及末次随访时行Frankel评分,观察随访期间植骨融合率、后凸畸形矫正状况.结果所有患者均获得随访,时间7个月~5年,末次随访时1例Frankel A级患者恢复至Frankel D级,3例Frankel B级患者恢复至Frankel D级,其余患者均恢复至Frankel E级.随访期间所有患者均取得骨性融合,融合时间3~12个月.术后1周Cobb角平均为5.1°,末次随访Cobb角平均为9.2°,Cobb角平均丢失约4.1°.结论 经肋椎关节手术入路治疗胸椎多椎体结核是一种较为理想的手术方式.     

改良Sundaresan法治疗上胸椎肿瘤

目的探讨采用改良Sundaresan法治疗上胸椎肿瘤的效果。方法自1999年1月～2003年10月共治疗上胸椎肿瘤患者14例,男9例,女5例;年龄26～65岁,平均43岁。原发性肿瘤10例(71.4%),转移瘤4例(28.6%)。T1肿瘤7例,T2肿瘤5例,T3肿瘤2例。采用改良Sundaresan手术入路,经下颈部和胸锁关节切口,切除胸锁关节的锁骨端,显露椎体肿瘤病灶,切除肿瘤椎体及其相邻椎间盘,解除对脊髓的压迫。椎体间采用切除的锁骨植骨或植入钛质网笼,颈椎前路带锁钢板内固定。脊髓损伤程度按Frankel分级标准评定。结果术后随访6个月～2年,平均10个月。采用改良Sundaresan手术入路可以较好地显示手术区域,利于病灶清除和内固定,避免损伤脊髓。术后脊髓功能均有不同程度改善,1例A级,恢复至B级;1例B级,恢复至D级;2例C级,1例恢复至D级,1例恢复至E级;4例D级,2例恢复至E级,2例无变化;6例E级无改变。所有患者肩关节功能未受到明显影响,肩关节外展术前90°～130°,平均125°;术后80°～120°,平均110°。结论采用改良Sundaresan法治疗上胸椎肿瘤效果好,创伤小,对肩关节功能无明显影响,适用于脊髓前方存在压迫的上胸椎椎体肿瘤。     

胸椎结核外科治疗不同术式选择探讨

目的探讨不同解剖节段胸椎结核外科治疗术式的选择策略及疗效。方法回顾分析2005年5月至2009年5月手术治疗36例成人胸椎结核的临床资料,其中男19例,女17例;年龄17~60岁,平均32.2岁;病变破坏2个椎体23例,3个椎体7例,4个椎体6例。术前所有患者均有不同程度的后凸畸形,后凸角10°~110°,平均21°。22例伴有神经功能障碍。将胸椎按照解剖特点分为颈胸结合部(C7~T2)、中部(T3~5)、下胸椎(T6~12)。依据解剖特点不同采用5种不同的手术入路(颈胸结合部前入路、经胸腔胸膜外入路、开胸、肋横突旁入路、后正中入路)对36例胸椎结核患者行一期病灶清除、植骨融合内固定术。结果所有患者随访18~48个月,平均26个月,术后胸背部疼痛减轻,切口一期愈合,术后1~3个月血沉逐渐恢复正常,术后后凸角度矫正至0°~60°,平均14°,自体骨植骨于术后3个月开始融合,22例伴有神经功能障碍者,术后Frankel分级提高1~2级,大部分完全恢复。结论根据胸椎结核病灶部位的解剖特点、累及的范围选择恰当的术式可有效清除结核病灶,矫正后凸畸形,重建脊柱的稳定性,改善神经功能,临床效果良好。     

一期后路内固定病灶清除植骨融合治疗上胸椎结核

目的探讨一期后路椎弓根钉内固定、病灶清除、植骨融合治疗上胸椎结核的临床疗效。方法自2009年3月至2011年1月,应用脊柱后正中切口一期行椎弓根钉内固定、切除肋骨头及横突行侧前方病灶清除、植骨融合治疗上胸椎结核12例,其中男10例,女2例;年龄9~45岁,平均36.2岁;病变节段:T2~31例,T3~52例,T4~66例,T5~62例,T61例;所有患者均以胸背部疼痛首诊并伴不同程度的神经功能障碍,术前后凸角15°~52°,平均30.2°;Frankel分级B级2例,C级2例,D级8例;入院时查血沉平均71 mm/h,术前血沉平均35 mm/h。结果术后随访6~22个月,1例患者手术切口皮缘坏死经换药后愈合,余患者均一期愈合。术后1~3个月内血沉恢复至正常水平,胸椎后凸畸形均明显改善。术后后凸角度10°~27°,平均19°;植骨融合时间4~7个月,平均5个月,至终末随访时无结核复发及内固定相关并发症。末次随访时2例Frankel分级B级者恢复至C级,2例C级者1例恢复至D级,1例恢复至E级,8例D级恢复至E级。结论一期后路椎弓根内固定、病灶清除、植骨融合治疗上胸椎结核手术入路简单,创伤小,有利于恢复脊柱稳定性,矫正后凸畸形,且操作安全,并发症少。     

后外侧入路减压椎间植骨融合内固定治疗胸椎管狭窄症的疗效及安全性

【摘要】 目的：探讨后外侧入路减压、椎间植骨融合、椎弓根螺钉内固定手术治疗胸椎管狭窄症的疗效及安全性。方法：2006年1月～2012年3月,收治单节段腹侧压迫致胸椎管狭窄症患者22例,男14例,女8例,年龄33～69岁,平均53.5岁。病程1~18个月,平均6.7个月。椎间盘突出部位：T7/8 1例,T8/9 4例,T9/10 9例,T10/11 8例。术前脊髓功能Frankel分级：B级5例,C级11例,D级6例。所有患者均行后外侧入路减压、椎间植骨融合、椎弓根螺钉内固定手术。采用Otani等评分系统进行术后疗效评估并计算临床优良率,评价治疗效果。结果：手术时间2.5~5h,平均3.2h,出血量400~1800ml,平均800ml。2例患者术后即刻有短暂脊髓功能障碍加重,经及时给予甲基强的松龙冲击、消肿、营养神经等治疗,分别于术后8h及24h开始逐渐恢复,其余20例患者术后即刻脊髓功能较术前恢复。术后随访24～60个月,平均40个月。末次随访时所有患者神经功能均明显改善,Frankel分级：C级3例,D级6例,E级13例。根据Otani等分级标准,优13例,良6例,可3例;优良率为86.36%。所有患者均获得骨性融合,均无内固定物松动、断裂等并发症发生。结论：后外侧入路减压、椎间植骨融合、椎弓根螺钉内固定手术治疗胸椎管狭窄症可取得良好的临床疗效,操作安全,并发症少。     

胸椎多椎体结核的手术治疗

目的探讨评价胸椎多椎体结核经胸腔前路病灶清除、椎管减压,一期植骨单钉棒内固定术的治疗效果。方法自2002年6月至2010年3月收治多椎体胸椎结核14例,男8例,女6例;年龄23～59岁,平均45岁。病变范围T4～10椎体,病变累及3个椎体5例,4个椎体6例,5个及以上椎体3例。术前Frankel评分2例B级,4例C级,8例D级。MRI均显示椎体破坏、椎旁脓肿,其中椎管内脓肿或致压物导致脊髓明显受压7例,压迫均来自脊髓前方,X线片测量后凸Cobb角为40°～22°,平均25°。均采用经胸腔前路病灶清除、椎管减压、一期椎体间植骨单钉棒内固定术。结果随访1～9年,平均5年6个月。脊髓功能恢复按Frankel分级,D级2例,E级12例。植骨全部骨性愈合,后突畸形矫正率为84%,后凸角平均矫正21°,无结核复发及继发脊柱后凸畸形。结论经胸腔前路病灶清除、椎管减压、一期椎体间植骨、单钉棒内固定是治疗胸椎多椎体结核的有效方法之一。     

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.