退变性腰椎侧凸后路长节段固定融合术后近端交界性后凸的危险因素分析

目的:探讨退变性腰椎侧凸(degenerative lumbar scoliosis,DLS)后路长节段固定融合术后发生近端交界性后凸(proximal junctional kyphosis,PJK)的危险因素。方法:回顾性分析2009年4月~2014年5月于我院行长节段(≥5个椎体)固定融合手术、年龄≥45岁、随访时间≥2年的DLS患者共60例。将随访时出现PJK的患者纳入PJK组,其余患者纳入对照组。用单变量分析比较两组患者个体资料、手术资料和影像学参数间的差异,找出潜在的危险因素,然后用Logistic回归分析确定独立危险因素。个体资料包括性别、年龄、体重指数(BMI)、骨密度(BMD)和T-值。手术资料包括固定融合椎体数、最上端固定椎(UIV)位置、最下端固定椎(UIV)位置、截骨操作和椎间融合。影像学参数包括侧凸Cobb角、胸椎后凸角(TK)、胸腰段后凸角(TLK)、腰椎前凸角(LL)、骨盆入射角(PI)、骨盆倾斜角(PT)、骶骨倾斜角(SS)、总矢状位序列(GSA)、矢状位平衡(SVA)和交界区后凸角(PJA1为UIV+1上终板与UIV下终板的夹角;PJA_2为UIV+2上终板与UIV下终板的夹角)等。结果:研究共纳入DLS患者60例,年龄63.2±6.4岁(45~74岁),术前Cobb角28.51°±10.94°(10.7°~55.1°),手术平均固定融合节段6.7±1.3个(5~9个)。随访40.3±11.1个月(24~59个月),末次随访时11例患者发生PJK(PJK组),49例患者未发生PJK(对照组),PJK发生率为18.3%。与对照组相比,PJK组有更多的BMD0.850g/cm2例数(100.0%vs 36.1%,P=0.005);更多的UIV位于T11-L1例数(100.0%vs 69.4%,P=0.030);更多的术前PJA19°例数(45.5%vs 10.2%,P=0.013)、术前TLK≥15°例数(63.6%vs 22.4%,P=0.012)、术前SS25°例数(90.9%vs 46.9%,P=0.016)、术后即刻PJA_2≥5°例数(100.0%vs 46.9%,P=0.001)和术后即刻PJA_2增长≥3°例数(90.9%vs 46.9%,P=0.016)。Logistic回归分析示术前PJA_19°(OR=19.432,P=0.017)、术前SS25°(OR=23.131,P=0.022)和术后即刻PJA_2增长≥3°(OR=22.382,P=0.025)为发生PJK的独立危险因素。结论:术前PJA_19°、术前SS25°和术后即刻PJA2增大≥3°是发生PJK的独立危险因素,BMD0.850g/cm~2、UIV位于T11-L1、术前TLK≥15°和术后即刻PJA_2≥5°是发生PJK的潜在危险因素。     

退变性腰椎侧凸患者椎旁肌退变与术后近端交界性后凸的相关性研究

目的:探讨退变性腰椎侧凸(degenerative lumbar scoliosis,DLS)患者术前腰椎椎旁肌肉的退变程度与后路长节段固定融合术后近端交界性后凸(proximal junctional kyphosis,PJK)发生的关系。方法:本研究共纳入52例DLS患者,根据末次随访是否发生PJK分为PJK组(10例)及无PJK(non-PJK)组(42例)。影像学评估包括脊柱骨盆矢状位参数、腰椎椎旁肌肌量(肌肉与椎体/椎间盘横截面积比值)以及肌肉-脂肪指数(肌肉与皮下脂肪的平均信号强度之比)。利用Logistic回归分析PJK发生的危险因素。比较两组患者一般资料、术前及随访时腰痛VAS及健康相关生活质量评分(SRS-22)。结果:本组患者PJK发生率为19.23%。患者手术年龄、性别、身体质量指数、患病时长、糖尿病、截骨及椎间融合、固定节段数、减压节段数、骨密度T值在PJK组及无PJK组均未见明显统计学差异。术前骨矿盐密度(bone mineral density,BMD)较低、术前胸腰段后凸角(TLK)较大、术中胸椎后凸角(TK)矫正过大、最上端固定椎(UIV)位于T12-L1、术后即刻交界性后凸角(PJA)过大、术前骶骨倾斜角(SS)较小、术后PJA变化值较大、腰背伸肌群脂肪退变明显可能与腰椎退变性侧凸长节段固定术后发生PJK相关。通过Logistic回归分析发现,术前SS25°(OR=12.902,P=0.046)、术后即刻PJA增大≥3.6°(OR=21.940,P=0.015)、腰背伸肌肌肉-脂肪指数≥27.65(OR=11.749,P=0.019)为发生PJK的独立危险因素。PJK患者的随访腰痛VAS及SRS-22功能状态评分较non-PJK组差。结论:DLS术后发生PJK患者,术前腰椎椎旁肌肌量较低、脂肪退变明显。术前SS25°、术后即刻PJA增大≥3.6°、腰背伸肌肌肉-脂肪指数≥27.65为发生PJK的独立危险因素。     

后路长节段固定融合术治疗腰椎退行性疾病术后近端交界性后凸的相关因素分析

目的对后路长节段固定融合术治疗腰椎退行性疾病(lumbar degenerative diseases,LDD)术后近端交界性后凸(proximal junctional kyphosis,PJK)的相关因素进行分析,为其预防提供理论依据。方法纳入后路长节段固定融合术治疗的105例腰椎退行性疾病患者,随访18个月,将PJK患者设为观察组,非PJK患者设为对照组,调查两组患者一般资料以及影像学资料,采用单因素与多因素Logistic回归分析确定术后PJK的独立危险因素。结果 105例患者术后发生PJK 20例,发生率19.05%。两组上端固定椎(upper instrumented vertebra,UIV)位于胸腰段、身体质量指数(Body Mass Index,BMI)、近端交界性后凸角(proximal junctional kyphosis angle,PJKA)、合并骨质疏松、骶骨倾斜角(sacral slope,SS)差异有统计学意义(P0.05); Logistic回归分析结果显示:PJKA10°(OR=2.435)、UIV位于胸腰段(OR=1.764)、合并骨质疏松(OR=2.215)、SS25°(OR=1.976),均是术后发生PJK的独立危险因素。结论 PJK发生率较高,UIV位于胸腰段、PJKA10°、合并骨质疏松、SS25°,均会增加后路长节段固定融合术治疗LDD术后PJK发生的风险。     

脊柱侧后凸/后凸畸形SRS-Schwab四级截骨术后近端交界性后凸的危险因素分析

目的:探讨脊柱侧后凸/后凸畸形患者SRS-Schwab四级截骨术后发生近端交界性后凸(proximal junctional kyphosis,PJK)的相关危险因素。方法:回顾性分析2011年5月～2015年12月于我院行SRS-Schwab四级截骨手术且具有完整临床及影像学资料的46例脊柱侧后凸/后凸畸形患者,其中男性24例,女性22例,手术时年龄23.1±19.7岁。记录患者体重指数、融合节段、最上端固定椎(upper instrumented vertebra,UIV)位置及置钉密度等。测量术前、术后3个月及末次随访时的胸椎后凸角(thoracic kyphosis,TK)、腰椎前凸角(lumbar lordosis,LL)、骨盆入射角(pelvic incidence,PI)、局部后凸角(segmental kyphosis,SK)、主弯Cobb角(main curve,MC)、矢状面平衡(sagittal vertical axis,SVA)及近端交界角(proximal junctional angle,PJA)。根据患者术后是否发生PJK分为非PJK组和PJK组,采用t检验、χ2检验或Fisher精确检验对比两组临床资料及影像学参数,利用多因素Logistic回归分析确定PJK发生的危险因素。结果:46例患者术后随访24～63个月(36.9±13.4个月),其中11例(23.9%)发生PJK,以Ⅰ型PJK(8/11)最为常见,8例发生于术后6个月内。PJK组和非PJK组患者性别、年龄、随访时间、体重指数、融合节段、骨密度、置钉密度、UIV位置均无统计学差异(P0.05)。PJK组患者术前TK40°(6/11)和SK矫正30°(7/11)的比例均高于非PJK组(P0.05)。两组患者间术前PJA、LL、MC、PI、SVA和术后及末次随访时TK、LL、MC、SK、PI、SVA改变均无统计学差异(P0.05)。回归分析结果显示术后SK矫正30°(OR=7.000,95%CI=1.591-30.800,P=0.010)是PJK发生的独立危险因素。PJK组术前PJA为7.5°±3.0°,术后3个月为20.8°±4.1°,末次随访时为22.0°±4.5°,交界性后凸未见明显加重。结论:脊柱侧后凸/后凸畸形患者SRS-Schwab四级截骨术后PJK发生率为23.9%,其主要发生于术后6个月内,脊柱后凸畸形过度矫正是其独立危险因素。     

腰椎退行性疾病后路手术术后近端交界性后凸危险因素分析

目的探讨腰椎退行性疾病(lumbar degenerative diseases,LDD)行后路固定融合术后近端交界性后凸(proximal junctional kyphosis,PJK)的发生情况及危险因素。方法纳入2014年1月～2017年1月采用后路固定融合治疗的167例LDD患者,术后随访18～38个月,观察术后PJK发生情况,分别设为PJK组与非PJK组。调查两组患者性别、年龄以及手术前影像学资料等,组间各项目通过单因素分析与多因素分析确定LDD后路固定融合术后PJK的独立危险因素。结果术后发生PJK 25例,发生率14.97%; PJK组与非PJK组身体质量指数(Body Mass Index,BMI)、合并骨质疏松、术前PJK角度(PJKA)、年龄、腰椎前凸角(LL)、骶骨倾斜角(SS)、融合节段数差异有统计学意义(P0.05);多因素logistic回归分析结果显示,BMI25 kg/m2(OR=3.778)、合并骨质疏松(OR=2.985)、PJKA10°(OR=3.567)、年龄70岁(OR=2.877)是术后发生PJK的独立危险因素。结论 LDD后路固定融合术后易发生PJK,BMI25 kg/m2、合并骨质疏松、PJKA10°、年龄70岁均会增加其发生风险。     

强直性脊柱炎胸腰椎后凸畸形截骨矫形术后近端交界性后凸的危险因素与临床意义

目的 :探讨强直性脊柱炎(ankylosing spondylitis,AS)胸腰椎后凸畸形矫形术后发生近端交界性后凸(proximal junctional kyphosis,PJK)的危险因素及表现形式。方法 :回顾性分析2002年1月~2015年12月接受矫形手术且随访大于2年的133例AS胸腰椎后凸畸形患者,男性118例,女性15例,年龄35.1±9.8岁(18~63岁)。收集患者临床资料,包括年龄、性别、体重指数、截骨方式和椎体融合节段。术前、术后及每次随访拍摄全脊柱正侧位片,并测量矢状面平衡(sagittal vertical axis,SVA)、胸椎后凸角(thoracic kyphosis,TK)、腰椎前凸角(lumbar lordosis,LL)、骶骨倾斜角(sacral slope,SS)、骨盆倾斜度(pelvic tilt,PT)、骨盆投射角(pelvic incidence,PI)和近端交界角(proximal junctional angle,PJA)。根据PJA将患者分为PJK组和非PJK组,利用卡方检验及t检验对比两组间临床资料及影像学参数。结果:133例患者平均随访3.6±2.2年(2.0~15.0年),11例发生PJK,平均在术后随访3.7年(0.3~15.0年)发生,PJA从术前5.5°±9.7°进展至21.2°±9.5°。PJK组手术年龄低于非PJK组(P0.01),PJK组行SPO人数比例高于非PJK组(P0.01)。PJK组术前PJA和SVA均低于非PJK组(P0.05)。两组间TK、LL、SS、PT和PI均无显著性差异(P0.05)。11例PJK患者中,有3种PJK表现形式,包括假关节(2例)、压缩性骨折(3例)和AS胸椎后凸畸形的自然进展(6例)。末次随访时,1例假关节PJK患者自发性愈合,1例AS胸椎后凸畸形自然进展的PJK患者行翻修手术,其余患者均予以随访观察。结论:AS术后PJK表现形式包括假关节、压缩性骨折和AS胸椎后凸畸形的自然进展。初次手术年龄、手术方式、术前PJA及SVA影响PJK的发生。     

成人退变性脊柱侧凸长节段内固定术后内科相关并发症的危险因素分析

目的:分析成人退变性脊柱侧凸长节段内固定术后的内科并发症的相关危险因素。方法:回顾性分析2012年1月~2016年1月于我院行后路长节段(内固定融合节段≥3个)椎弓根螺钉内固定矫形术治疗的成人退行性脊柱侧凸的患者资料82例,其中男24例,女58例,年龄55~71(63.9±4.6)岁。根据有无内科并发症分为无内科并发症组(58例)和有内科并发症组(24例)。内科并发症包含肺炎、脓血症、尿路感染、中枢神经病变、周围神经病变、充血性心力衰竭、深静脉血栓、心肌梗死、心律失常、胸腔积液、凝血功能障碍、胃肠道并发症和肾功能异常等。比较两组术前和末次随访的侧凸Cobb角、骨盆投射角与腰椎前凸角之差(PI-LL)和矢状面垂直轴(SVA)等影像学差异。术前、术后4周、52周和104周使用Oswestry功能障碍指数(Oswestry disability index,ODI),日本骨科协会(Japanese Orthopaedic Association,JOA)评分和视觉模拟量表(visual analogue scale,VAS)对患者临床症状进行评分。使用单因素分析对性别、年龄、BMI、术前贫血、糖尿病、高血压病史以及吸烟情况、心脏病史、症状持续时间、手术固定节段数量、椎板减压节段数量、手术时间、术中出血量情况和术后住院时间等潜在危险因素进行检测。采用多元Logistics回归分析内科并发症的独立危险因素。结果:出现内科并发症的患者29.3%。高血压、糖尿病和贫血的发病率分别为30.5%、20.7%和9.8%。术后并发症中感染14例(17.1%),心肺功能异常9例(11.0%),胃肠道疾病11例(13.4%),肾功能异常1例(1.2%)。无内科并发症组脑脊液漏的发病率显著低于内科并发症组(19.0%vs 54.2%,P=0.001),术前两组影像学参数中Cobb角、PI-LL和SVA无统计学差异(P0.05);术后两组影像学参数比较Cobb角、PI-LL和SVA无统计学差异(P0.05)。在多因素Logistic回归模型中确定的独立危险因子包括BMI(OR 1.127,P=0.011),吸烟(OR 3.15,P=0.032)、住院时间(OR 1.16,P=0.047)和症状持续时间较长的患者(OR 1.33,P=0.025)。内科并发症组的患者末次随访ODI、JOA评分和VAS与术前相比均有显著改善(P0.05),但两组间差异无统计学意义(P0.05)。结论:成人退变性脊柱侧凸患者长节段椎弓根螺钉内固定术后内科并发症相关危险因素包括心脏病史、糖尿病、吸烟和住院时间。     

退变性脊柱侧凸患者后路矫形术后腰椎前凸指数对矢状面平衡的预测作用

目的:探讨术后腰椎前凸指数(lumbar lordosis index,LLI)对退变性脊柱侧凸患者后路矫形术后矢状面平衡的预测作用。方法:回顾性分析2005年1月~2011年12月在我院行单一后路矫形术的57例退变性脊柱侧凸患者,其中男9例,女48例,年龄56.3±10.8岁(48~70岁)。纳入标准为年龄45岁以上、内固定节段≥5个节段且随访≥2年的患者。在术前、术后即刻和末次随访的站立位全脊柱X线片上测量矢状面垂直轴(SVA)、胸椎后凸角(TK)、腰椎前凸角(LL)、骨盆入射角(PI)、骨盆倾斜角(PT)和骶骨倾斜角(SS),计算腰椎前凸指数(LLI=LL/PI)。根据末次随访时患者矢状面平衡情况分为正常组(A组,末次随访时SVA≤5cm且PT≤25°)和失代偿组(B组,末次随访时SVA5cm或PT25°)。应用相关性分析研究57例患者术前、术后即刻和末次随访时LLI与其他脊柱骨盆矢状面参数的相关性,使用独立样本t检验分别比较A组和B组患者术前、术后即刻和末次随访的矢状面参数,P0.05为差异有统计学意义。结果:A组患者41例,B组16例。术后随访时间4.4±1.9年(2~8年),其中A组随访4.3±1.8年,B组随访4.6±1.9年,两组随访时间无统计学差异(P=0.725)。57例患者LLI与相应时间点的PI、LL、PT、SVA和LL丢失值均有显著相关性(P0.05),但与TK和SS无相关性。两组间术前LLI的差异无统计学意义(0.45±0.18 vs.0.47±0.21,P=0.638);A组术后即刻LLI为0.89±0.13,显著大于B组术后即刻的LLI(0.61±0.14)(P=0.005)。A组末次随访时SVA为2.73±2.62cm、PT为20.34°±4.28°,而B组患者末次随访时SVA为7.81±3.26cm、PT为29.81±5.13°,两组间SVA和PT的差异均有统计学意义(P0.01)。结论:术后即刻LLI重建不良的退变性脊柱侧凸患者在随访中可能出现矢状面失代偿的风险,而良好的术后LLI重建可以降低随访中脊柱矢状面失平衡的风险。     

腰椎退行性疾病术后近端交界性后凸的危险因素及治疗

背景:老年腰椎退行性疾病的手术治疗中,有时需要进行长节段固定融合,在获得稳定的同时,可能带来固定节段近端交界性后凸(PJK)。目的:回顾腰椎长节段固定融合病例,对PJK发生的危险因素、发生后的处理、预防方法等进行分析。方法:选取2013年1月至2018年6月行腰椎长节段固定融合术后患者117例,最终82例获得随访(随访率70%),记录患者年龄、性别、身高、体重、随访时间、骨密度、体重指数、固定节段等。手术前后及随访时行X线检查,使用Surgimap软件测量胸椎后凸角(TK)、腰椎前凸角(LL)、脊柱矢状轴(SVA)、近端交界角(PJA)、脊柱整体力线(GSA)、骨盆入射角(PI)、骨盆倾斜角(PT)、骶骨倾斜角(SS),记录Oswestry功能障碍指数(ODI)。对发生PJK的患者记录Hart-ISSG PJKSS量表得分。结果:远端固定到S1的患者以及近端固定到胸腰段的患者PJK发生比例更高。PJK组术前LL、SS较非PJK组更小,术前SVA、PI-LL、GSA较非PJK组更大。末次随访时,27例患者发生PJK(32.9%,27/82),其中9例患者行翻修手术。结论:长节段固定融合手术时远端固定椎应尽量选择L5及L5近端,而近端固定椎尽可能避开胸腰段。对于术前矢状位失衡明显的患者应重视矢状位平衡的恢复,Hart-ISSG PJKSS量表对PJK患者翻修手术具有一定指导价值。     

Ⅰ型神经纤维瘤病合并脊柱侧凸术后近端交界性后凸的临床分析

[目的]探讨Ⅰ型神经纤维瘤病(neurofibromatosis type 1, NF1)合并营养不良性脊柱侧凸术后发生近端交界性后凸(PJK)的发生率和危险因素。[方法]回顾性分析2007年1月～2015年6月期间接受后路矫形手术、有完整临床及影像学资料的103例NF1合并营养不良性脊柱侧凸患者的临床资料,男49例,女54例。术前、术后3个月及末次随访时测量脊柱骨盆参数、局部后凸角(SK)、主弯Cobb角及近端交界角(PJA),记录PJK发生情况并分析其危险因素。[结果]术后平均随访(34.97±14.47)个月,22例发生了PJK,其中16例于术后6个月内发生,最常见的类型为Ⅰ型(63.64%)和Ⅱ型(27.27%)。PJK组术前PJA为7.42°,术后6个月为21.83°,末次随访时为23.82°。12例患儿接受支具治疗,1例行翻修手术。PJK组患者术前TK60°、SK矫正40°、UIV位于T3～5和T8～9的发生率均高于非PJK组(P0.05),而两组患者术前PJA、LL、UIV固定方式及融合节段等差异均无统计学意义(P0.05)。回归分析结果显示TK60°(OR=3.758,P=0.032)、 UIV位于T_(3～5)或T_(8～9)(OR=5.837,P=0.030)是PJK发生的独立危险因素。[结论] NF1合并营养不良性脊柱侧凸术后PJK主要发生于术后6个月内;术前后凸畸形、UIV位于T_(3～5)和T_(8～9)是其发生的危险因素。     

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.