后路截骨联合椎弓根内固定矫形治疗僵硬性脊柱侧后凸畸形

目的探讨经后路截骨联合椎弓根内固定矫形治疗僵硬性脊柱侧后凸畸形疗效。方法对26例僵硬性脊柱侧后凸畸形患者进行后路截骨、椎弓根内固定矫形。8例行后路Ponte截骨,13例行椎弓根截骨术(PSO)联合Ponte截骨,5例行全椎体切除术(VCR)。比较患者术前、术后和末次随访时Cobb角的变化及C7中垂线与骶骨中垂线距离的变化。结果患者均获得随访,时间12~60个月。侧凸Cobb角:术前30°~135°(90.7°±30.6°),术后12°~30°(18°±5.6°),矫正率为82.5%,末次随访13°~32°(20°±5.8°),丢失4.3%;后凸Cobb角:术前20°~60°(40.6°±18.5°),术后10°~26°(16.8°±6.2°),矫正率为85%,末次随访13°~30°(20.5°±7.0°),丢失3.7%;C7中垂线与骶骨中垂线距离:术前3.8~6.5(5.1±1.3)cm,术后0.3~1.3(0.7±0.3)cm,末次随访0.4~1.7(0.8±0.3)cm。所有患者未发生神经损伤等并发症,仅1例患者术后3个月出现内固定松动,经延长固定节段后骨性融合。结论术前充分的评估,选择合适的后路截骨方式,联合椎弓根内固定矫形治疗僵硬性脊柱侧弯,能有效矫正畸形和恢复脊柱冠、矢状面平衡。     

经椎弓根楔形截骨矫正强直性脊柱炎后凸畸形

目的研究经腰椎椎弓根楔形截骨矫正强直性脊柱炎后凸畸形的手术方法和治疗效果。方法2003年1月~2006年12月收治12例男性强直性脊柱炎后凸畸形患者,平均年龄36岁。手术采用一期后路经L3椎弓根截骨矫形,截骨节段上方和下方至少2个节段椎弓根螺钉矫正固定。测量患者术前和术后颌眉线/垂线夹角和脊柱侧位X线L2~4椎体Cobb角度。结果患者颌眉线/垂线夹角由术前平均76.3°矫正到术后平均17°,而L2~4的Cobb角度由术前平均后凸6.7°矫正到术后平均前凸48.6°。所有患者能够平视行走,矢状面平衡和步态得到明显改善。结论对于严重强直性脊柱炎后凸畸形患者,经腰椎椎弓根楔形截骨矫形是一种安全有效的治疗方法。     

一期后路经椎弓根截骨病灶清除植骨内固定治疗胸腰段脊柱结核

[目的]探讨治疗胸腰段脊柱结核一期完成病灶清除、矫正脊柱后凸畸形、植骨、后路钉棒固定的临床疗效。[方法]自2004年1月~2008年6月收治活动期胸腰段单节段脊柱结核伴后凸畸形患者34例,采用一期后路椎弓根截骨病灶清除(在胸椎段,先切取左右肋骨后段),钛笼植骨,后路矫形系统内固定。根据术前、术后X线分析植骨融合情况以及脊柱后凸畸形矫正效果。[结果]34例患者随访时间9~28个月,平均18个月,X线片示结核病灶清除彻底,脊柱畸形矫正,Cobb角由术前20°~45°矫正到术后3°~5°,植骨块无移位,2例再次行前路补充植骨术。结核无复发。[结论]该手术入路简捷,病灶清除彻底,360°环形解除压迫,畸形矫正满意,三柱固定,植骨融合,后期脊柱稳定,缩短了卧床时间,减少了相应的并发症。     

后路半椎体切除椎弓根螺钉内固定治疗小儿先天性脊柱畸形

目的评价后路半椎体切除、椎弓根螺钉内固定治疗小儿先天性脊柱畸形的临床疗效.方法2003年6月～2005年6月应用后路半椎体切除、椎弓根螺钉内固定和自体骨短节段植骨融合治疗28例小儿先天性脊柱侧凸畸形患者,男10例,女18例,年龄1.6～7岁,平均3.8岁.完全分节半椎体24例,半椎体伴对侧分节障碍4例.术后定期复查脊柱X线片,观察脊柱融合、畸形矫正率及内固定稳定情况.结果术中发生胸膜损伤和脑脊液漏各1例,分别经胸腔和伤口引流痊愈;术后切口浅表感染1例,经抗炎和换药处理治愈;无神经系统损伤.随访23～48个月,平均35个月,术前主弯冠状面Cobb角平均为35.2°±2.2°,术后为5.2°±1.2°,末次随访为7.4°±1.1°,丢失2.2°;后凸角平均为26.2°±3.1°,术后为4.2°±0.8°,末次随访为4.8°±1.0°,丢失0.6°;均获得良好骨融合,融合时间3～6个月,平均4.2个月;无内固定失败及假关节形成.结论后路半椎体切除、椎弓根螺钉内固定植骨融合能安全有效地矫正小儿先天性脊柱侧凸畸形,并能达到稳定的短节段内固定及优良的融合效果.     

经后路L1椎体截骨短节段椎弓根内固定术治疗脊柱后凸畸形

目的探讨L1椎体楔形截骨椎弓根螺钉内固定术矫治胸腰段脊柱后凸畸形的效果。方法56例胸腰段后凸畸形患者,均行经后路L1椎体截骨短节段椎弓根内固定,全部采用单节段截骨。结果本组平均手术时间3．7（2．8～4．6）h,术中平均出血量1980（700—3600）ml。术后后凸角由手术前平均54．5°矫正到16．5°,矫正角度38°。随访6～72个月,其间畸形矫正无明显丢失,除2例出现下肢麻痹外,其余均未出现神经系统并发症。结论L1椎体楔形截骨椎弓根螺钉内固定术矫治脊柱后凸畸形固定可靠,矫形效果满意。     

脊柱陈旧骨折后凸畸形的矢状面重建

目的:介绍脊柱陈旧骨折后凸畸形矢状面重建的手术方法。方法:18例胸腰椎陈旧骨折并后凸畸形患者采用两种手术方式治疗:14例采用经椎弓根椎体截骨短节段内固定,4例采用前后联合入路减压、前路截骨Z-plate钢板内固定。结果:随访6个月~3年,无骨不连等发生,有1例TSRH固定患者2枚螺钉发生松动。无脊髓损伤并发症。神经功能Frankel分级均有1级以上提高,术后矢状指数平均6°。结论:经椎弓根椎体截骨短节段内固定和前后联合入路减压、前路截骨内固定,可有效地矫正胸腰椎陈旧骨折遗留的脊柱矢状面畸形,并重建脊柱的稳定性。     

双椎体截骨术矫正重度强直性脊柱炎后凸畸形

目的:探讨经椎弓根双椎体截骨矫正重度强直性脊柱炎后凸畸形的可行性及其疗效.方法:2003年1月～2007年12月收治15例颌眉角90°以上重度强直性脊柱炎后凸畸形患者,平均年龄34.5岁.手术均采用后路经椎弓根连续或者间隔椎体行双椎体截骨矫形,并采用椎弓根螺钉内固定.测量患者术前和术后身高、颌眉角、矢状面失平衡距离和截骨部位Cobb角评价疗效.结果:手术时间231～420min,平均326min;术中出血950～4600ml,平均2290ml.6例患者硬脊膜与椎板粘连,切除椎板时出现硬脊膜破裂并脑脊液漏,经严密缝合及控制引流后伤口按期愈合;1例患者矫形中已融合的C5/6处发生骨折,术后给予硬颈托固定6个月后融合;1例患者术后出现肺部感染,经积极抗炎治疗痊愈出院.患者身高由术前122.5±10.4cm矫正到术后163.6±10.0cm,颌眉角由术前平均102.6°±9.4°矫正到术后19.5°±11.6°,矢状面失平衡距离由术前43.7±5cm矫正到术后11.3±6.1cm,脊柱侧位X线片上截骨部位Cobb角由术前后凸67.1°±24.5°矫正到术后前凸9.7°±25.1°,经统计学处理各指标术后与术前比较均存在显著性差异(P<0.01).结论:对于颌眉角90°以上重度强直性脊柱炎后凸畸形患者,经椎弓根双椎体截骨可以有效矫正患者后凸畸形,外观和功能均可得到明显改善.     

经后路椎弓根截骨短节段椎弓根钉内固定治疗脊柱后凸畸形

目的探讨经椎弓根单椎体截骨短节段椎弓根钉内固定治疗脊柱后凸畸形的临床疗效。方法2001年6月~2003年11月,采用经后路椎弓根截骨短节段椎弓根钉内固定治疗16例脊柱后凸畸形患者。其中男11例,女5例,年龄24~51岁。强直性脊柱炎12例,陈旧性胸腰椎骨折脱位伴不完全截瘫2例,椎体发育不良2例。病程7~25年,平均12.8年。手术前、后均行脊柱全长X线片检查,测量胸椎后凸角、腰椎前凸角、骶骨水平角及骶骨后上角至脊柱矢状轴线的距离,评定植骨愈合情况、内固定位置及手术并发症。按Bridwell-Dewald脊柱疾患疼痛及功能评定标准进行手术前后疗效评价。结果术中出血700~2000ml,平均1100ml;术中硬脊膜破裂1例;术后发生麻痹性肠梗阻1例,下肢短暂性麻痹2例。术后获随访18~35个月,平均25.6个月。植骨愈合满意,无延迟愈合或不愈合。最后随访时,腰椎前凸角从术前9.6±16.4°,矫正至术后42.6±14.3°(P<0.05),平均矫正角度为33°;骶骨水平角的改变与此类似。胸椎后凸角手术前后改变不明显,而骶骨后上角至脊柱矢状轴线的距离由术前97.5±45.6mm降至术后10.7±9.6mm(P<0.05)。术后疼痛、工作及社交情况较术前都有明显改善。结论经后路椎弓根椎体截骨短节段椎弓根钉内固定治疗脊柱后凸畸形,矫正度数大,手术相对安全,可取得较理想的放射学矫形效果及临床疗效。     

经后路顶椎椎弓根全椎体截骨矫正胸腰椎后凸畸形

目的探讨经后路顶椎椎弓根三柱截骨治疗脊柱后凸的临床疗效。方法2003年6月－2006年6月,采用经后路顶椎椎弓根三柱截骨治疗42例脊柱后凸患者,其中陈旧胸腰椎骨折20例、椎体发育不良8例、结核性10例、强直性脊柱炎4例。评定脊柱后凸矫正情况、植骨融合情况、内固定位置、手术并发症、腰痛及Oswestry功能评分的变化。结果术后随访6—21个月,平均15个月。植骨融合满意,无延迟愈合或不愈合。术前后凸Cobb角度平均为霹8．5°术后为20．6°,平均矫正角度为35．3°。术前患者腰痛VAS评分平均为7．5分,术后3．6分。术前ODI平均为57．6％,术后31.7％。结论经后路顶椎椎弓根截骨、椎弓根螺钉固定治疗胸腰椎后凸畸形,矫正角度大,手术视野开阔,手术相对安全,可获得满意的放射学矫形效果和临床疗效。     

应用头颅-骨盆环牵引辅助后路截骨治疗重度脊柱侧后凸畸形的临床效果

目的探讨应用头颅-骨盆环牵引辅助后路截骨矫形治疗重度脊柱侧后凸畸形的临床效果。方法回顾分析2014年3月至2018年3月贵州省骨科医院脊柱外科收治的重度脊柱侧后凸畸形患者32例的临床资料。其中男14例,女18例,年龄(17.5±4.8)(14~23)岁。均行Halo骨盆牵引后后路截骨矫形手术治疗。牵引力取患者可承受的极限,牵引时间为(3.2±0.6)(3~4)周,后行后路截骨内固定融合术。对患者治疗前左右侧屈位、牵引后和术后的侧后凸矫正率进行比较。采用SPSS 24.0软件对数据进行统计学处理。结果32例患者均顺利完成手术。行经椎弓根椎体截骨(pedicle subtraction osteotomy,PSO)或邻椎截骨12例、Smith-Petersen截骨(Smith-Petersen osteotomy,SPO)或Ponte截骨20例。未见脊髓与神经损伤并发症发生。治疗前脊柱冠状面Cobb角为(136.8±38.0)°(96°~172°),矢状面Cobb角为(90.4±24.0)°(45°~125°)。患者平卧左右侧屈位侧凸矫正率为(8.9±3.2)%,Halo骨盆牵引后侧凸矫正率为(37.6±4.3)%,后路截骨矫形术后侧凸矫正率为(68.7±4.8)%;牵引后矢状面侧凸矫正率为(30.7±5.6)%,后路矫形术后矢状面侧凸矫正率(60.6±4.3)%;各时间点差异均有统计学意义(均P<0.05)。结论应用Halo头颅-骨盆牵引辅助后路截骨矫形治疗重度脊柱侧后凸畸形患者,可预测矫形效果,简化手术,降低操作难度,提高畸形矫正率,安全有效。     

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.     

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.     

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.     

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.     

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.     

Systemic analgesia adapted to the children's condition

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.     

Intraoperative autotransfusion is associated with modest reduction of allogeneic transfusion in prosthetic hip surgery

Background: The efficacy of intraoperative salvage and washing of wound blood and the predictors of allogeneic red cell transfusions in prosthetic hip surgery are insufficiently known.
Methods: In 96 patients, undergoing primary or revision surgery, salvaged and washed red cells and, if necessary, allogeneic blood were used to keep haematocrit not lower than 33%. The bleeding of red cells during hospital stay was calculated from the red cell balance. The preoperative red cell reserve (millilitres of red cells in excess of a haematocrit of 33%) was estimated and the difference between this volume and the total bleeding of red cells was retrospectively used to classify patients with regard to the need for red cells. Stepwise regression analysis was used to define patient-related variables associated with allogeneic blood transfusion.
Results: Preoperative knowledge of the type of operation (primary, revision), the preoperative red cell reserve, and the body mass could predict roughly half of the need for banked blood (r²=0.45). Only one-third of the total bleeding of red cells was retransfused. For complete avoidance of allogeneic blood, autotransfusion was most effective in patients with a moderate need (0–4 u). However, 32% of such patients required allogeneic blood.
Conclusions: Autotransfusion has a limited efficacy to decrease the need for allogeneic blood, and other blood-saving methods should be added for this purpose. It is difficult to predict the need for allogeneic blood preoperatively.     

缺氧对肾小管上皮细胞分泌外泌体的影响

目的    观察缺氧对肾小管上皮细胞分泌外泌体的影响,探讨外泌体在缺氧致肾脏损伤中的作用及机制。 方法    （1）常氧（21% O₂）及缺氧（1% O₂）分别处理大鼠肾小管上皮细胞（NRK-52E）48 h,收集细胞上清液并使用高速梯度离心法分离外泌体。采用透射电镜、纳米示踪分析、Western印迹、蛋白浓度定量鉴定并比较两组外泌体的基本特性。（2）在共培养实验中,以不同浓度（1、10、50、100、300 mg/L）的常氧外泌体、缺氧外泌体分别干预脂多糖（LPS）诱导的大鼠原代腹腔巨噬细胞,使用实时荧光定量PCR与酶联免疫吸附试验（ELISA）法分别检测巨噬细胞白细胞介素6（IL-6）、肿瘤坏死因子α（TNF-α）、诱导型氮氧化物合酶（iNOS）水平;使用Western印迹法检测巨噬细胞磷酸化（p）STAT/STAT及细胞因子信号传导抑制蛋白1（SOCS1）的蛋白表达;最后,使用实时荧光定量PCR法检测常氧外泌体与缺氧外泌体中炎性反应相关微RNA（microRNA,miR）的表达差异。 结果    （1）离心得到的囊泡具有外泌体典型的结构,粒径小于150 nm,表达外泌体标志蛋白CD63,说明分离得到外泌体。缺氧对肾小管上皮细胞分泌的外泌体形态、粒径分布比例无明显影响,但提高了外泌体的分泌量。（2）缺氧外泌体相比于常氧外泌体促进了LPS诱导的M1型巨噬细胞IL-6、TNF-α、iNOS 的表达和分泌（均P＜0.01）,同时提高STAT的磷酸化水平并减少SOCS1的蛋白表达（均P＜0.01）;对炎性反应相关microRNA检测发现缺氧外泌体中miR-155、miR-27a表达量较常氧外泌体明显升高（P＜0.05）。 结论    缺氧可改变外泌体的生物学功能,表现为协同促进LPS诱导的M1型巨噬细胞的表型转化,这可能是慢性肾脏病微炎性反应状态持续的原因之一。     

In Vitro Function and Durability Assessment of a Novel Polyurethane Heart Valve Prosthesis

Abstract While flexible-leaflet, central-flow prosthetic heart valves promise relief from anticoagulation therapy, they continue to be restricted by inadequate durability. In consequence, a novel trileaflet valve, made entirely from polyurethane, has been developed. A batch of 6 consecutively manufactured polyurethane valves was subjected to hydrodynamic function and accelerated fatigue testing. Computerized data acquisition and control systems have been introduced to improve valve testing methodologies. In terms of hydrodynamic function, the polyurethane valve demonstrates transvalvular pressure gradients similar to those for a bioprosthetic valve (Carpentier-Edwards) and levels of retrograde flow significantly less than those for either the bioprosthetic valve or a bileaflet mechanical valve (St Jude Medical). The equivalent of 10 years of cycling without failure has been exceeded by all 6 polyurethane valves in accelerated fatigue tests with 2 valves remaining intact after 674 million cycles (equivalent to approximately 17 years) in continuing tests. Highspeed photography revealed considerable differences in leaflet motion between valves cycled at accelerated and physiological rates.     

Negative pressure ventilation vs. spontaneous assisted ventilation during rigid bronchoscopy: A controlled randomised trial

Background: Ventilation during interventional rigid bronchoscopy (IRB) under general anaesthesia (jet ventilation, positive pressure ventilation and spontaneous assisted ventilation) may offer some difficulties. This study compares the effectiveness during IRB of intermittent negative pressure ventilation (INPV) and spontaneous assisted ventilation (SAV). Methods: Thirty-eight patients submitted to IRB were randomised into two groups: SAV or INPV. All patients received a total intravenous anaesthesia; INPV patients were paralysed. Pre-and intra-operative arterial blood gases and O₂ flow through a rigid bronchoscope were assessed. The endoscopist applying a subjective score evaluated the operating conditions. Results: Patients of the INPV group, as compared to the SAV group, required a lower dosage of fentanyl (2.6 ± 1.8 (μg · kg^?1· h^?1 vs. 6.6 ± 4.8 μg · kg^?1· h^?1), a lower O₂ supply (3.3 ± 2.8 1/min vs. 11.6 ± 3.4 1/min), a shorter recovery time (5.4 ± 2.9 min vs. 9.8 ± 7.1 min) and no manually assisted ventilation (0 ± 0 vs. 1 ± 1.1 nd?/procedure). Intraoperative PaCO₂ was higher in the SAV (8.1 ± 1.3 kPa) than in the INPV group (5.0 ± 1.6 kPa) and intraoperative pH differed in the two groups (7.26 ± 0.05, SAV vs. 7.47 ± 0.08, INPV). Operating conditions, as assessed by a subjective score, were considered better with INPV than with SAV (4.9 vs. 4.3). Conclusions: As compared to SAV, INPV in paralysed patients during IRB reduces administration of opioids, shortens recovery time, prevents respiratory acidosis, excludes the need for manually assisted ventilation, reduces 02 need and affords optimal surgical conditions. INPV appears a safe, non-invasive and effective ventilatory management during IRB.