山羊可动人工腰椎复合体研制及在体生物力学研究

目的：研制适用于山羊腰椎次全切除术后重建的可动人工腰椎复合体（mobile artificial lumbar complex,MALC）,测试MALC的稳定性及术后腰椎节段运动功能。方法：选取18只1～2岁雄性波尔山羊（体重35～45 kg）,将其分为对照组、融合组、非融合组,每组6只。根据术前腰椎X线片、CT及MRI检查,针对非融合组设计个体化山羊MALC,并进行3D打印制作。分别对3组进行手术,对照组仅显露椎体及椎间盘;融合组切除L4部分椎体及上下完整椎间盘组织,进行钛网植骨腰椎接骨板固定手术;非融合组同法切除椎体及椎间盘,植入MALC。术后6个月拍摄山羊腰椎正侧位X线片了解内植物有无脱位、移位及断裂,并在力学测试仪上对标本进行生物力学试验,测量L2,3、L3,4、L4,5椎间隙的运动范围（range of motion,ROM）和L2-5整体腰椎ROM。结果：设计MALC进行3D打印,制造其组件人工椎体及上下人工终板,半球体结构采用高交联聚乙烯材料应用精密车床加工而成,并完成假体组装。术后6个月腰椎正侧位X线片示腰椎融合内植物及MALC植入位置良好,未见移位脱位。腰椎标本体外生...     

CT辅助山羊腰椎解剖测量及与人体腰椎的对比研究

目的:通过对山羊腰椎的解剖测量以及与人体腰椎的对比研究,为腰椎假体的动物模型建立奠定基础。方法:通过计算机辅助软件Mimics 16.0对波尔山羊新鲜腰椎标本及健康成人腰椎的椎体、椎弓根、椎间盘等部位的解剖参数进行采集,最终运用统计学软件对两者腰椎解剖特点进行对比研究。结果:山羊椎体前高中高后高,最大值分别为(38.7±2.9)、(40.1±2.6)、(40.7±2.7)mm。其终板宽度大于其深度,整体呈心形或肾形外观。山羊上终板向外凸出,下终板凹陷较小,最大值为(1.6±0.6)mm。山羊椎弓根高自L1至L6不断增大,最大值为(30.5±1.9)mm;其椎弓根宽与夹角随着椎体序列的增加先减小后增大,最小值分别为(6.7±0.4)mm与(45.9±2.6)°。山羊椎间盘前高中高后高,三者随着椎间隙的变化数值波动较小;其椎间孔高与宽亦变化较小,分别在(12.9±0.3)~(14.3±1.0)mm与(5.7±1.0)~(6.7±0.9)mm波动。对比结果显示山羊腰椎椎体高、椎弓根高及夹角明显大于人类(P0.05),而其终板宽与深、椎间盘高等明显小于人类(P0.05)。此外,两者某些结构如椎弓根高、椎间盘高等随着椎体序数的增加亦呈现出不同变化规律。结论:山羊腰椎虽然在某些方面如终板及椎间孔形态等与人体存在相似性,但是在诸多方面仍存在较大差异。掌握山羊腰椎的解剖特点及与人体之间的差异对于腰椎假体及相关技术的山羊动物研究具有重要的指导意义。     

非融合技术人工椎间盘在山羊体内模型建立的效果研究

目的通过建立非融合技术人工椎间盘(artificial disk of non-fusion technology,ADNFT)的山羊体内模型,研究其喷钛涂层骨长入、固定效果及非融合技术,为临床应用提供可行性证据。方法选择10只成年健康山羊作为实验对象,体重35~55 kg,羊龄10~24个月,随机分成A、B两组,每组各5只,经腰椎前外侧入路,行非融合技术人工椎间盘置换术,A、B组分别在术后3、6个月行腰椎正侧位的影像学检查,并分别在术后3、6个月取出包括假体在内的周围骨组织和软组织,常规制作标本后分别行病理、扫描电镜检查。通过腰椎影像学、病理及扫描电镜评价假体的固定效果、喷钛涂层骨长入及人工椎间盘的活动度。结果 10只山羊均建模成功,术后取出假体及周围组织的病理结果及电镜下可见假体喷钛涂层骨组织长入良好,人工椎间盘的钴铬钼合金、硅胶及喷钛涂层与周围组织相容性良好,腰椎X线片示假体位置良好,无松动,人工椎间盘有一定的活动度。结论非融合技术人工椎间盘的喷钛涂层骨长入良好,与椎体的固定效果可靠,材料的组织相容性好,具有非融合技术的效果。     

腰椎关节突人工关节的初步研究

目的探讨临床应用腰椎关节突人工关节的可行性。方法选择12具国人尸体腰椎标本,测量椎体和椎间盘高度;研制假体装置ZJS,并应用于3例退行性腰椎管狭窄并失稳患者,重建腰椎稳定性,不做椎骨间植骨融合,观察其腰腿疼症状的缓解程度、X光片测量腰椎活动度和椎间盘高度,评价其初步的临床疗效。结果国人腰椎椎体后缘高度(23.43±3.10)mm~(34.45±3.28)mm,椎间盘后缘高度(5.38±1.36)mm~(7.96±2.05)mm。3例患者随访11~16个月,症状明显缓解,满意程度高。术后X片显示手术椎节活动度:前屈后伸3°,左右侧屈3.5;°手术节段椎间盘后缘间隙高度能维持于中立位状态3.5~4.5 mm,在脊柱后伸活动时该高度亦无明显降低。结论国人腰段脊柱具备置入ZJS的条件;近期临床观察结果显示,退行性腰椎管狭窄并失稳患者经后路椎管减压,置入ZJS既能重建腰椎稳定性,保持手术节段的椎间孔高度,又能保留手术椎节的部分活动功能,是一种值得进一步研究的治疗腰椎退行性病变的非融合手术技术。     

Topping-off手术治疗腰椎退行性疾病的影像学分析

目的:评价Topping-off手术治疗连续双节段腰椎退行性疾病的影像学改变。方法 :2008年8月~2012年12月,35例连续双节段腰椎退行性椎管狭窄症(其中上位病变节段为轻或中度退变)患者在我院接受手术治疗。其中男23例,女12例,年龄62.6±18.9岁(30~79岁)。所有患者均接受腰椎单节段融合(PLIF)+上位节段棘突间动态稳定(置入Coflex)手术(Topping-off手术),其中L4/5置入Coflex+L5/S1融合14例,L3/4置入Coflex+L4/5融合21例。回顾性分析患者术前及末次随访时X线片上Coflex置入节段及其上位相邻节段的椎间隙高度、椎间活动度、椎体偏移、椎间隙角及腰椎前凸角;在MRI上对Coflex置入节段和其上位相邻节段椎间盘退变情况进行改良Pfirrmann分级。结果:患者均安全完成手术,手术时间为112±21min(95~155min),出血量为403±111ml(300~520ml)。均未出现硬脊膜破裂、神经损伤等相关并发症。随访24.8±12.8个月(11~65个月)。术后末次随访时Coflex置入节段及其上位相邻节段椎间隙前缘高度、椎间隙后缘高度与术前比较均无统计学意义(P0.05);Coflex置入节段椎间隙角较术前显著性增大(t=-1.8,P0.05);Coflex上位相邻节段椎间隙活动度(过伸位角度-过屈位角度)、椎间隙角及腰椎前凸角与术前比较均无统计学意义(P0.05)。24例随访2年以上患者MRI检查显示Coflex置入节段及其上位相邻节段椎间盘的改良Pfirrmann分级情况与术前相同。结论:Topping-off手术可以保持Coflex置入节段良好的稳定性,并保留该节段部分运动功能及其上位相邻节段节段正常活动,减少了上位相邻节段退变发生的危险因素。     

聚乙烯醇水凝胶人工髓核置入对腰椎运动影响的生物力学研究

目的：研究髓核摘除后聚乙烯醇水凝胶人工髓核置入对腰椎活动度和椎间隙高度的影响.方法：对7具新鲜成人尸体L4/5正常椎间隙、髓核摘除后和置入人工髓核后在8.0Nm扭矩下的屈伸、侧弯和旋转的活动度（ROM）、中性区（NZ）和椎间隙高度变化进行测试、比较.结果：髓核摘除后,L4/5椎间屈伸、侧弯、旋转的ROM和NZ较正常组显著增加（P＜0.05或0.01）,在0和200N的负荷下椎间隙高度较相同情况下正常组分别下降1.2mm和1.7mm;置入人工髓核后,相对于正常椎间隙,L4/5椎间屈伸、侧弯、旋转的ROM和NZ无明显差异,较髓核摘除组明显下降（P＜0.05或0.01）,在0N和200N的负荷下椎间隙高度较相同情况下髓核摘除组分别增加1.6mm和2.0mm.结论：聚乙烯醇水凝胶人工髓核置入椎间盘切除后的椎间隙可有效恢复椎间隙高度,维持腰椎节段正常的三维运动功能稳定性.     

腰椎间盘高度与椎间孔相关的解剖学研究

目的动态观察腰椎间盘高度丢失、造成腰椎间孔狭窄和神经根压迫的形态学变化,为临床诊断和治疗提供解剖学依据。方法采用6具正常成人腰椎解剖标本(L1-S1),腰椎间盘正常自然高度为对照组(A组);用同一标本行腰椎间盘切除,椎间隙分别插入4、3、2和1mm厚度的硅胶垫片,并且轴向施加压力,为4个实验组(B、C、D、E组)。然后动态观察和测量腰椎间孔大小与神经根受压迫的情况。结果直接观察和测量结果显示A组神经根位于椎间孔的上1/2;脊神经前根直径由L1(1.1±0.3)mm逐渐增大到L5(2.0±0.9)mm;脊神经后根直径由L1(2.0±1.1)mm逐渐增大到L5(3.8±0.4)mm;背根神经节最大直径由L1(3.9±0.8)mm逐渐增大到L5(7.1±0.9)mm。在椎间孔矢状面上脊神经前根位于背根神经节的腹侧5或7点钟处。B组全部腰椎间孔矢状径缩小,但是神经根未受压迫。C组L3,4、L4,5和L5S1椎间孔出现垂直狭窄,椎间盘膨出将神经根向头侧抬起,上位椎体的椎弓根下缘下移,神经根和脊神经节受到垂直方向压迫。D组L4,5和L5S1神经根和脊神经节受到来自前方的腰椎间盘和后方黄韧带以及下位腰椎的上关节突的横向压迫。A组与E组相比较,神经根袖与硬膜囊的夹角L3由33.6°±6.5°增大到39.7°±7.1°,L4由29.3°±7.5°增大到40.1°±5.2°和L5由20.1°±5.3°增大到46.2°±7.3°。结论下腰椎间盘高度≤3mm可以作为椎间孔狭窄诊断的参考标准。对于非手术失败的病例,手术行椎间孔减压,恢复椎间隙高度以及腰椎稳定性是治疗椎间孔狭窄的关键。     

阻断双侧终板营养途径构建山羊椎间盘退变模型

目的通过建立山羊腰椎双侧终板营养途径阻断的动物模型,观察椎间盘退变(IDD)的情况,研究椎间盘营养途径与IDD的相关性。方法选取8只24月龄雌性关中山羊,每只山羊L2~3、L3~4作为实验椎间盘,麻醉后在平行于终板2 mm的椎体骨质处造成骨缺损,并使用骨水泥填塞,阻断椎体和终板之间的营养通路,L1~2、L4~5作为对照椎间盘。分别于术后4、12、24、48周行X线、MRI检查,各时间点随机处死2只山羊,采集椎间盘标本,计算骨水泥有效阻断面积、椎间高度指数(DHI)和Pfirrmann分级,并行HE、Masson三色、蛋白多糖、番红O染色组织学检查。结果术后骨水泥有效阻断面积达49.6%~69.6%(60.7%±5.3%)。术后48周时实验椎间盘DHI百分比为60.5%~81.7%(72.7%±5.6%),椎间高度丢失较对照差异有统计学意义(P<0.01);术后48周时实验椎间盘Pfirrmann分级为3~5(4.0±0.7)分,较对照差异有统计学意义(P<0.01)。组织学检查证实,实验椎间盘术后12周即发生退变,并随时间(24、48周)逐步加重。结论骨水泥填塞阻断双侧终板营养途径可以构建山羊IDD的动物模型,阻断终板营养途径可以导致IDD发生。     

后方韧带复合体对腰椎椎间融合术后早期相邻节段退变的影响

目的探讨后方韧带复合体对腰椎椎间融合术后早期相邻节段退变的影响。方法 2000年1月至2010年1月在我科实施后路腰椎减压椎间融合内固定治疗L4~5椎间盘突出患者60例。A组(30例)行保留后方韧带复合体的腰椎椎间融合术(posterior lumbar interbody fusion,PLIF),B组(30例)行切除后方韧带复合体的PLIF术。比较两组手术前、后日本骨科协会(Japanese orthopaedic association,JOA)评分及改善率。术前、末次随访时测量腰椎X线片上L3~4椎间盘的高度和椎间隙动态角度、L3~4椎体滑移距离并进行比较。术前及末次随访时对L3~4椎间盘进行Pfirrmann分级。结果手术前、后两组患者的JOA评分差异有统计学意义(P0.05),术后两组JOA评分差异均无统计学意义(P0.05),两组之间改善率差异无统计学意义(P0.05)。A组9例患者出现了L3~4节段的邻近节段退变(adjacent segment disease,ASD),B组17例出现了L3~4节段的ASD。其中A、B两组均有2例患者为有症状的ASD。术前两组患者X线片上L3~4椎间盘的高度、椎间隙动态角度、L3~4椎体滑移距离相比差异均无统计学意义(P0.05),而末次随访时差异有统计学意义(P0.05)。A组末次随访时Pfirrmann分级1级6例,2级22例,3级2例,无4、5级病例。B组末次随访时Pfirrmann分级1级4例,2级24例,3级2例,无4、5级病例。结论腰椎椎间融合术中保留后方韧带复合体可减少术后早期相邻节段退变的发生。     

椎间融合器的置入方式对腰椎融合效果的影响

目的 :探讨椎间融合器置入方向和位置对腰椎椎间融合术患者临床疗效的影响。方法 :回顾性分析2010年6月～2014年6月在我院行L4/5或L5/S1单节段腰椎融合术患者的临床资料,依据融合器置入方式分为斜向置入组(斜向组,100例)和横向置入组(横向组,100例)。记录两组患者年龄、性别、骨密度、体重指数(body mass index,BMI)及手术节段,术前和末次随访时行Oswestry功能障碍指数(Oswestry disability index,ODI)及疼痛视觉模拟(visual analog scale,VAS)评分。术后1周、6个月、12个月及末次随访时行X线片、CT检查,测量术前、术后1周和末次随访时融合节段的椎间隙高度,术后1周和末次随访时的植骨面积、椎间融合器距离椎体边缘的距离;术后6个月、12个月和末次随访时采用改良Brantigan评分评估椎间融合情况。统计随访过程中内固定断裂和再发生腰背部疼痛情况。结果:两组患者年龄、性别、骨密度、BMI及手术节段均无统计学差异(P0.05),术前手术节段椎间隙高度、ODI及VAS评分无统计学差异(P0.05);两组患者均获得24个月以上随访,术后1周和末次随访时的ODI和VAS评分较术前均有显著性改善(P0.05);两组患者术中使用融合器的高度无统计学差异(P0.05),术后融合节段椎间隙高度较术前增加无统计学差异(P0.05);术后1周椎间隙平均植骨面积横向组(322.26±32.36mm2)大于斜向组(198.40±22.08mm2)(P0.05);斜向组椎间融合器距离椎体左右侧距离分别为8.5±1.2mm、21.2±1.5mm,距椎体后缘距离4.2±0.5mm,横向组椎间融合器距离椎体左右侧距离分别为13.1±1.8mm、14.2±1.4mm,距椎体后缘距离9.8±0.8mm,两组比较有统计学差异(P0.05)。术后6个月融合率横向组(90%)大于斜向组(71%)(P0.05),12个月、24个月两组融合率比较无统计学差异(P0.05);末次随访椎间隙高度丢失度横向组(1.8±1.6mm)低于斜向组(2.6±1.7mm)(P0.05),植骨面积横向组(423.56±23.29mm2)大于斜向组(299.64±21.68mm2)(P0.05);随访过程中斜向组4例出现断钉,5例再发生腰背部疼痛;横向组无断钉,2例再发生腰背部疼痛,两组比较有统计学差异(P0.05)。结论:腰椎融合手术采取斜向和横向置入椎间融合器均能取得满意的疗效,但椎间融合器横向置入能更好地维持椎间隙高度,早期融合率更高,可减少术后钉棒断裂、腰背部疼痛再发生等并发症的发生。     

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.     

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.     

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.     

Dilemma of Membrane Biocompatibility and Reuse

Abstract: Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation. leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.