青少年特发性脊柱侧凸不同弯型患者椎体和椎间盘楔形变的差异及临床意义

目的:比较不同弯型、不同Cobb角的青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)患者椎体和椎间盘楔形变及其对整体Cobb角构成的差异,探讨其临床意义。方法:2007年1月~2009年6月对收治的110例单弯型AIS患者按弯型分组,其中主胸弯39例(A组),胸腰弯33例(B组),主腰弯38例(C组)。每组根据侧凸Cobb角大小再分为<40°和≥40°两个亚组。分别测量每个主弯范围内所有椎体和椎间盘的楔形变角(楔变角),并分别计算椎体与椎间盘楔变角之和分别占整个主弯Cobb角的百分比(楔变角所占Cobb角比率)。结果:全部患者平均年龄13.6±1.9岁;平均Cobb角34.4°±10.5°;平均Risser征2.4±1.7。三组间平均年龄、Cobb角、Risser征均无显著性差异(P>0.05)。A组椎体楔变角及所占比率明显大于椎间盘(21.9°±5.6°比13.7±5.9°,62.3%比37.7%,P<0.001),B组与C组椎间盘楔变角及所占比率明显大于椎体(24.1°±9.2°比10.4°±3.8°,69.0%比31.0%,P<0.001;25.1°±7.2°比7.7°±2.4°,76.6%比23.4%,P<0.001)。各组内Cobb角≥40°患者的椎体与椎间盘楔变角均显著大于Cobb角<40°患者的楔变角(P<0.001)。随Cobb角增加,A组患者椎体楔变角占整体Cobb角比率仍然大于椎间盘,而B组和C组患者椎间盘楔变角占整体Cobb角比率仍然大于椎体。三组顶椎楔变角均与相应Cobb角大小成显著线性正相关(P<0.001)。结论:AIS各种弯型侧凸均存在不同程度的椎体与椎间盘楔形变。主胸弯Cobb角构成以椎体楔形变为主,胸腰弯和主腰弯则以椎间盘楔形变为主,提示不同弯型间可能存在不同的生物力学发生机制。     

胸腰段特发性脊柱侧凸的前路矫正术

目的评价胸腰段/腰段特发性脊柱侧凸经前路矫正术的临床效果。方法1998年1月~2004年1月,76例胸腰段/腰段特发性脊柱侧凸患者接受前路选择性矫正融合术。患者共76例,男19例,女57例,平均年龄为16.2岁(13~27岁)。按照Lenke分型,Ⅴ型41例,Ⅵ型35例。其中Lenke Ⅴ型术前胸腰段侧凸Cobb角平均51.3°(38°~65°),胸段侧凸Cobb角平均35.5°(23°~41°);Lenke Ⅵ型术前胸腰段侧凸Cobb角平均53.4°(46°~68°),胸段侧凸Cobb角平均39.2°(27°~51°)。所有患者均接受侧前路矫正选择性胸腰段融合。术后以及随访中对胸腰段侧凸矫正以及胸段代偿矫正情况进行分析对比,同时采用SRS-22评分评价患者手术前后的功能状况。结果患者均安全完成手术,无严重并发症发生。所有患者均随访2年以上(2~5年)。Lenke Ⅴ型组术后胸腰段侧凸Cobb角平均11.2°(3°~15°),胸段侧凸Cobb角平均8.3°(2°~11°),最终随访时分别为13.2°(5°~17°)和10.1°(4°~15°),无躯干冠状面失代偿发生;LenkeⅥ型组术后Cobb角平均16.3°(8°~21°),胸段侧凸Cobb角平均13.7°(11°~19°),最终随访时分别为17.5°(11°~24°)和15.2°(14°~21°);仅1例发生躯干冠状面失代偿,但不需要进一步治疗。两组之间无统计学差异。所有患者均在术后以及最终随访时填写了SRS-22评分表,结果显示两组患者均对治疗结果表示满意。结论胸腰段/腰段特发性脊柱侧凸经前路矫正、选择性融合可以获得良好矫正,术后胸段弯曲能够获得较好的代偿矫正,并在远期随访中维持矫正效果和躯干冠状面的平衡。     

青少年发育不良性腰椎滑脱症合并脊柱侧凸的临床分析

目的:对青少年发育不良性腰椎滑脱症患者合并脊柱侧凸的情况进行调查并对侧凸情况做术后随访。方法:回顾性分析2007年3月~2017年10月于我院行滑脱复位固定融合手术治疗的28例青少年发育不良性腰椎滑脱症患者,滑脱节段均为L5,依据Meyerding滑脱分度将其分为重度滑脱(Ⅲ、Ⅳ、Ⅴ度)组与轻度滑脱(Ⅰ、Ⅱ度)组。以术前全脊柱正侧位X线片评估两组患者有无脊柱侧凸(Cobb角≥10°诊断为脊柱侧凸)、滑脱情况(滑脱程度、Dubousset腰骶角)以及脊柱-骨盆矢状位参数(骨盆入射角、骶骨倾斜角、骨盆倾斜角)。青少年腰椎滑脱合并的脊柱侧凸分为特发性侧凸和痉挛/疼痛性侧凸两大类,其中痉挛/疼痛性侧凸又分为单纯痉挛性侧凸和"滑脱性"侧凸两种,"滑脱性"侧凸主要由滑脱椎体的旋转造成。对有侧凸的患者测量其末次随访时的侧凸角度以了解侧凸改善情况。结果:发育不良性重度腰椎滑脱15例,年龄12.5±2.6岁,男2例,女13例;轻度滑脱者13例,年龄14.5±2.6岁,男6例,女7例,两组年龄、性别比例及各脊柱-骨盆矢状位参数均无统计学差异(P0.05)。重度滑脱组的Dubousset腰骶角明显小于轻度滑脱组(55.6°±17.0°vs.83.3°±18.4°,P0.05)。28例患者中合并脊柱侧凸者14例,其中重度滑脱组合并脊柱侧凸13例,轻度滑脱组中仅1例符合脊柱侧凸诊断,两组合并侧凸比例有统计学差异(86.7%vs.7.7%,P0.001)。重度滑脱患者术前冠状位平均Cobb角明显大于轻度滑脱患者(18.1°±13.0°vs.4.6°±3.7°,P=0.001)。重度滑脱组中脊柱侧凸的构成情况:特发性侧凸5例,Cobb角11.6°~52.6°,平均30.2°±17.0°;痉挛/疼痛性侧凸8例,其中单纯痉挛性侧凸4例(Cobb角12.5°~17.5°,平均14.8°±2.1°),"滑脱性"侧凸4例(Cobb角11.2°~12.6°,平均11.9°±0.6°)。对13例重度滑脱伴侧凸患者进行术后随访,其中12例获得随访,随访时间为1~100个月(23.8±28.7个月),末次随访时单纯痉挛性侧凸的平均矫正率为92%,特发性脊柱侧凸的平均矫正率为7.5%,"滑脱性"脊柱侧凸的平均矫正率为4%。结论:青少年发育不良性腰椎滑脱症患者中,重度滑脱患者合并脊柱侧凸的比例高于轻度滑脱者,发育不良性重度腰椎滑脱与脊柱侧凸可能具有相关性,其中单纯痉挛性侧凸在滑脱复位固定融合术后可大部分自发矫正。     

儿童胸椎结核的临床及影像学特点

目的：探讨儿童胸椎结核的临床及影像学特点，为其临床诊断和治疗提供参考。方法：1997年6月～2007年6月我院收治69例儿童胸椎结核患者，其中男36例，女33冽，年龄1～14岁，平均5．9岁，对其临床及影像学特点进行归纳分析。根据脊髓神经功能受损与否分为截瘫组与脊髓神经功能正常组，比较其受累椎体数目。根据后凸Cobb角角度和患病节段分组，比较其截瘫率：结果：病程平均15．1个月，受累椎体平均3．2个，后凸Cobb角平均37．5&#176;，合并截瘫26例（37．7％）。首诊原因以脊柱后凸畸形（34．8％）多见：常见症状以下肢症状（50．7％）多见，包括下肢无力、步态不稳等；常见体征以后凸畸形（92．8％）多见。截瘫组受累椎体数为3．6&#177;1．5（2～8）个，多于脊髓神经功能正常组的2．9&#177;1．0（2-6）个，有昆菩性差异（P〈0．05）；上胸椎结核截瘫率为84．6％（11／13），高于中下胸椎结核的26．8％（15／56），有显著性差异（P〈0．05）：后凸Cobb角≥30&#176;者截瘫率为45．8％（22／48），高于后凸Cobb角〈30&#176;者的截瘫率19．0％（4／21），有显著性差异（P〈0．05）；病程、受累椎体数、后凸角度问有相关性（相关系数r为0．338—0．535，P〈0．05）。35例胸椎MRI示2个或2个以上相邻椎体T1低信号，1．2高或混杂信号；椎旁软组织影边缘清楚，T1低信号，1．2高或混杂信号；受累椎间盘消失或1．2低信号。MRI对椎间盘受累及椎管受累的显示优于X线平片及CT（P〈0．05）。结论：儿童胸椎结核早期易延误诊断．易导致严重后凸畸形。截瘫的危险因素包括上胸椎、多椎体受累和后凸Cobb角≥30&#176;．MRI检查有助于早期诊断。     

青少年特发性脊柱侧凸与神经源性脊柱侧凸患者椎体和椎间盘的楔形变及其临床意义

目的:观察青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)与神经源性脊柱侧凸(neurological scoliosis,NS)患者的椎体和椎间盘的楔形变情况,探讨其临床意义。方法:对35例AIS患者和31例NS患者(继发于Chiari畸形)应用Cobb法测量胸椎和腰椎每个侧凸范围内顶椎及其上、下各两个椎体和相应椎间盘的楔变角,计算其占整个侧凸角度的百分比(楔变率),得出侧凸范围内5个椎体的平均楔变率和4个椎间盘的平均楔变率。应用SPSS10.0统计软件进行统计分析,组间比较采用单因素方差分析。结果:相同病因、相同侧凸部位、相同Cobb角分组情况下,椎体与椎间盘的楔变率存在显著性差异(P0.05)。相同病因、相同侧凸部位,Cobb角60°组的椎体楔变率和椎间盘楔变率与Cobb角≥60°组比较均无显著性差异(P0.05)。相同侧凸部位、相同Cobb角分组,AIS组椎体和椎间盘的楔变率分别与NS组比较均无显著性差异(P0.05)。结论:AIS与NS患者椎体与椎间盘的相对楔形变方式相同,AIS患者的椎体楔形变可能是继发的。在治疗脊柱侧凸时,即便是较小角度的脊柱侧凸,都应该考虑到其存在椎体和椎间盘的楔形变。     

青少年特发性胸腰弯脊柱侧凸伴结构性腰弯患者腰椎椎体磁共振弥散成像参数的变化

目的 :探讨青少年特发性胸腰弯脊柱侧凸伴结构性腰弯患者腰椎(L1~L5)椎体凹凸侧磁共振弥散加权成像(diffusion-weighted imaging,DWI)参数的变化规律。方法:收集2015年6月~2016年6月在我院就诊的青少年特发性胸腰弯脊柱侧凸伴结构性腰弯的女性患者共30例,年龄10~18岁,Cobb角40°~60°。对患者(侧凸组)及10例同年龄段健康青少年(对照组)腰椎(L1~L5)椎体进行磁共振DWI,测量侧凸患者腰椎椎体凹凸侧及对照组腰椎椎体左右侧表观弥散系数(apparent diffusion coefficient,ADC)值,分别对侧凸患者腰椎椎体凹凸侧及对照组腰椎椎体左右侧ADC值进行比较,同时对侧凸患者和对照组腰椎椎体ADC均值进行比较,分析顶椎椎体凹凸侧ADC差值与Cobb角之间的关系。结果:对照组腰椎各节段间椎体(L1~L5)左侧/右侧的ADC值均无显著性差异(F=0.752,P=0.559;F=0.604,P=0.661);侧凸组腰椎各节段间椎体凹侧/凸侧的ADC值亦无显著性差异性(F=1.268,P=0.301;F=1.250,P=0.291)。对照组腰椎椎体左侧ADC值与右侧比较无显著性差异[(0.439±0.041)×10~(-3)mm~2/s vs(0.423±0.042)×10~(-3)mm~2/s,t=1.047,P=0.288];侧凸组腰椎椎体凹侧ADC值与凸侧比较有显著性差异[(0.391±0.012)×10~(-3)mm~2/s vs(0.553±0.037)×10~(-3)mm~2/s,P0.01],凸侧ADC值与对照组比较显著性增大,凹侧与对照组比较显著性减小。顶椎椎体凹凸侧ADC差值与Cobb角无显著相关性(r=0.024,P=0.721)。结论 :青少年特发性胸腰弯脊柱侧凸伴结构性腰弯患者腰椎(L1~L5)椎体凹凸侧DWI参数存在显著性差异。     

不同手术入路对青少年特发性胸腰段/腰段脊柱侧凸矫形术后椎间角变化的影响

目的 分析比较青少年特发性胸腰段/腰段脊柱侧凸前路或后路矫形固定融合术后椎间角的变化.方法 回顾性分析此类患者接受前路(组A)或后路(组B)矫形固定融合手术前后侧凸Cobb角及椎间角的变化.结果 组A共30例患者,组B共12例患者.组A与组B术前、术后主弯冠状面Cobb角分别为48.9°和11.7°,44.3°和5.3°,矫形率分别为76.1%和87.7%.随访时冠状面Cobb角分别为18.1°和7.7°.术前、术后及随访时椎间角组A分别为3.2°、5.6°和8.2°,组B分别为3.3°、3.6°和3.2°.二组间比较,术后侧凸冠状面Cobb角、侧凸矫形率、随访时侧凸冠状面Cobb角、冠状面Cobb角丢失组B均优于组A(P=0.022,P:0.022,P=0.005,P=0.019);术后椎间角组A与组B比较差异无统计学意义(P=0.068),随访时椎间角组A较组B大(P=0.001),随访时椎间角丢失组A较组B多(P=0.043).结论 对于青少年特发性脊柱胸腰段/腰段侧凸,采用后路全椎弓根螺钉矫形固定融合手术随访时椎间角及椎间角丢失优于前路手术.     

后路半椎体切除椎弓根钉内固定治疗先天性脊柱侧凸畸形的中期疗效分析

目的探讨后路半椎体切除椎弓根钉内固定治疗非嵌顿型半椎体导致的先天性脊柱侧凸畸形的矫形效果、安全性及并发症情况。方法回顾性分析自2010-01—2015-01采用后路半椎体切除椎弓根钉内固定治疗的16例先天性脊柱侧凸畸形。结果 16例均获得随访,随访时间平均55(39~76)个月。术后即刻主侧凸Cobb角、上代偿性侧凸Cobb角、下代偿性侧凸Cobb角、节段后凸Cobb角较术前明显改善,但末次随访时主侧凸Cobb角、下代偿性侧凸Cobb角、节段后凸Cobb角矫正度数较术后即刻出现丢失,差异有统计学意义(P0.05)。手术前后胸椎后凸Cobb角、腰椎前凸Cobb角比较差异无统计学意义(P0.05)。结论后路半椎体切除椎弓根钉内固定治疗先天性脊柱侧凸畸形安全有效,能直接去除致畸因素,获得牢靠的固定、良好的畸形矫正及脊柱平衡,而且手术时机越早,矫形效果越好。     

一期后路半椎体切除治疗半椎体所致先天性脊柱畸形

目的探讨一期后路半椎体切除内固定治疗半椎体所致先天性脊柱畸形的可行性及疗效。方法自1998年10月～2003年6月,对11例半椎体所致的先天性脊柱畸形采用一期后路半椎体切除内固定矫形。男5例,女6例,年龄2.5～23岁,平均15.4岁。单个半椎体7例,多个半椎体2例,半椎体合并对侧骨桥或肋骨融合2例;病变位于胸段(T3、T4、T6、T9)4例、胸腰段(T11 1例、T12 1例、L1 2例)4例、腰段(L3 1例、L4 2例)3例。术前侧凸Cobb 角为44°～82°,平均60.5°;伴后凸畸形3例,Cobb角分别为13°(L4)、27°(L3)和48°(L1)。躯干偏移4~36.7mm,平均21.2mm。内固定使用CD2例,中华长城2例,SYNERGY1例,TSRH6例。结果手术时间平均为185min;术中出血平均850ml。长节段固定9例;短节段单侧固定1例,短节段双侧固定1例。术后平均随访1年10个月。固定融合节段为2~11个椎体,平均8.4个。侧凸Cobb角为0°～24°,平均18.7°,平均矫正率为69.1%;3例伴后凸畸形患者,后凸Cobb角分别为-11°、-8°和0°。术后躯干偏移0~16.3mm,平均为6.2mm,侧、后凸和躯干偏移无明显矫正丢失。术中并发症包括椎弓根或椎板骨折2例;1例术后出现切口渗液及脊柱轻度不稳定。结论应用一期后路半椎体切除、内固定治疗半椎体所致的先天性脊柱畸形效果满意,近期疗效可靠。     

前后路手术治疗儿童静止期脊柱结核后凸畸形

目的探讨前后路手术治疗儿童静止期脊柱结核后凸畸形的疗效。方法2006年7月至2007年8月,手术治疗儿童静止期脊柱结核后凸畸形患者16例,男9例,女7例;年龄6～15岁,平均11岁;脊柱结核病程2～13年,平均81个月。病变部位为T6～L3,其中累及1个椎体2例,2个椎体3例,3个椎体7例,4个椎体2例,5个椎体2例。所有患者确诊脊柱结核后均行正规抗结核药物治疗1年以上,均无低热、盗汗等症状,血细胞沉降率、C反应蛋白均在正常范围,均未行病灶清除等手术治疗。其中4例有神经损害表现,表现为双下肢的麻木、乏力,尚可行走;其余12例表现为背部后凸畸形,尚无其他不适。手术方式为前路松解、减压、支撑植骨、内固定术及后路截骨、后凸矫形、植骨、椎弓根螺钉内固定术,通过观察患者植骨融合情况、外观变化、后凸及侧凸角度变化、神经功能变化来评价疗效。结果全部获得随访,随访时间2～3年,平均28个月。所有患者均融合良好,无一例发生假关节及内固定失败,患者外观改善明显,4例有神经损害的患者均恢复正常。术前后凸Cobb角为40°～68°,平均55.8°,术后后凸Cobb角为-4°～49°,平均21.7°,随访时后凸Cobb角为-4°～52°,平均23.2°,矫正丢失0°～5°,平均1.5°;术前侧凸Cobb角为0°～22°,平均6.9°,术后侧凸Cobb角为0°～6°,平均0.8°,随访时侧凸Cobb角为0°～8°,平均0.9°,矫正丢失0°～2°,平均0.1°。无一例发生神经并发症,1例发生伤口延迟愈合,经换药2周后愈合。结论采用前后路手术治疗儿童静止期脊柱结核后凸畸形,既可矫正后凸畸形,又可预防患儿在生长发育过程中畸形的进一步加重。     

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.     

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.     

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.