Mitek可吸收钉固定自体四股胭绳肌肌腱重建前交叉韧带21例

目的介绍关节镜下自体半腱肌，股薄肌移植重建前交叉韧带并利用Mitek可吸收钉固定的手术方法，观察其近期临床疗效。方法利用Mitek可吸收钉固定自体腘绳肌肌腱重建前交叉韧带21例。于术后3、6、12个月随访，分别进行Lysholm功能评分和SF-36自我评分，以及Lachman和KT-2000客观体征评价，部分患者行MRI检查。结果21例全部获得随访，Lysholm功能评分和SF-36评分较术前明显提高。2例Lachman征阳性，轴移试验均为阴性，KT-2000测试结果2例双侧差距超过5mm。结论自体四股腘绳肌移植重建前交叉韧带可获得满意的临床效果，Mitek可吸收钉固定可提供良好的初始稳定，无排异反应，对MRI检查无影响。     

关节镜下应用EndoPearl与Intrafix固定双侧绳肌肌腱一期重建膝关节前后交叉韧带

目的探讨关节镜下应用EndoPearl与Intrafix固定双侧腘绳肌肌腱同时重建膝关节前后交叉韧带的近期临床效果。方法对2004年6月~2005年3月收治的10例膝关节前后交叉韧带同时断裂的患者,切取双侧腘绳肌腱,2条半腱肌腱和2条股薄肌腱分别对折成四束,折端固定同直径EndoPearl。关节镜下利用两组移植物同时分别重建膝前后交叉韧带。股骨端应用可吸收界面螺钉顶压固定EndoPearl与移植肌腱,胫骨端应用Intrafix固定四束肌腱。结果10例均获得随访,平均7.5个月(6~15个月),切口Ⅰ期愈合,无感染。其中新鲜损伤4例,陈旧性损伤6例,合并后外侧复合体损伤3例,均予同期修复,合并内侧副韧损伤6例,未予特殊处理,5例曾急诊修复腘动静脉。术后3个月膝关节活动范围均超过120°,无伸膝受限,后抽屉试验Ⅰ度阳性2例,其余为阴性;Lyshlom评分(92.6±3.2)分。结论关节镜下应用EndoPearl与Intrafix固定双侧腘绳肌肌腱同时重建膝关节前后交叉韧带方法确切,可有效恢复膝关节功能。     

Rigidfix与Intrafix螺钉在前交叉韧带重建中的应用

目的探讨关节镜下应用可吸收Rigidfix横穿钉与Intrafix膨胀挤压螺钉固定4股单束自体腘绳肌腱,重建前交叉韧带(anterior cruciate ligament,ACL)的手术方法和临床疗效。方法 2009年7月至2012年7月芜湖市中医院关节二科共诊治45例ACL损伤患者,取自体腘绳肌腱4股单束在关节镜下使用Intrafix膨胀挤压螺钉固定胫骨端,Rigidfix横穿钉固定股骨端,重建ACL。观察术后膝关节的稳定性及疗效。结果本组45例患者术后均得到随访,随访12~48个月,平均32个月。关节功能良好,Lysholm评分术前(42.30±4.20)分,术后12个月(92.54±2.10)分,术后评分明显提高,差异有统计学意义(P0.01)。结论关节镜下使用可吸收Rigidfix横穿钉与Intrafix膨胀挤压螺钉固定4股单束自体腘绳肌腱重建ACL,疗效肯定,操作简单,能够提供早期的初始稳定性和后期的生物稳定性,适宜基层医院临床应用推广。     

关节镜下应用EndoPearl与Intrafix固定双侧腘绳肌肌腱一期重建膝关节前后交叉韧带

目的 探讨关节镜下应用EndoPearl与Intrafix固定双侧腘绳肌肌腱同时重建膝关节前后交叉韧带的近期临床效果.方法 对2004年6月～2005年3月收治的10例膝关节前后交叉韧带同时断裂的患者,切取双侧腘绳肌腱,2条半腱肌腱和2条股薄肌腱分别对折成四束,折端固定同直径EndoPearl.关节镜下利用两组移植物同时分别重建膝前后交叉韧带.股骨端应用可吸收界面螺钉顶压固定EndoPearl与移植肌腱,胫骨端应用Intrafix固定四束肌腱.结果 10例均获得随访,平均7.5个月(6～15个月),切口Ⅰ期愈合,无感染.其中新鲜损伤4例,陈旧性损伤6例,合并后外侧复合体损伤3例,均予同期修复,合并内侧副韧损伤6例,未予特殊处理,5例曾急诊修复腘动静脉.术后3个月膝关节活动范围均超过120°,无伸膝受限,后抽屉试验Ⅰ度阳性2例,其余为阴性;Lyshlom评分(92.6±3.2)分.结论 关节镜下应用EndoPearl与Intrafix固定双侧腘绳肌肌腱同时重建膝关节前后交叉韧带方法确切,可有效恢复膝关节功能.     

关节镜下应用钮扣式钢板固定四股自体股腘绳肌腱重建前交叉韧带

目的 探讨关节镜下应用钮扣式钢板固定四股自体腘绳肌腱重建膝关节前交叉韧带（anterior cruciate ligament,ACL）的临床疗效. 方法 对32例前交叉韧带损伤者在关节镜下应用钮扣式钢板固定四股腘绳肌腱重建术.术前和术后进行Lachman试验、轴移试验评估膝关节的稳定性,用Lysholm评分法评价膝关节功能.术前常规行MRI及膝关节正侧位、髌骨轴位X线片检查,排除前交叉韧带起止点骨性撕脱. 结果 32例随访3.5～29个月,其中25例＞12个月.所有病例膝关节不稳定感明显改善.术前Lachman试验阳性32例,轴移试验阳性28例.Lysholm综合评分51.8±5.6.术后Lachman试验30例阴性,2例弱阳性,轴移试验均为阴性,膝关节功能Lysholm综合评分为90.7±2.5.3例关节积液,经关节穿刺抽吸后吸收. 结论 关节镜下应用钮扣式钢板固定四股自体腘绳肌腱重建膝ACL的近期临床疗效良好.     

关节镜下自体腘绳肌腱重建膝关节前交叉韧带

目的：探讨关节镜下自体4股腘绳肌腱、生物可吸收挤压螺钉固定重建前交叉韧带（ACL）的临床效果。方法：31例经关节镜检查证实为前交叉韧带断裂的患者，男27例，女4例；年龄17～40岁，平均25岁。其中合并半月板损伤26例，合并局部软骨损伤3例，软骨Ⅰ～Ⅱ度退变16例。均于关节镜下行自体4股腘绳肌腱和软组织生物可吸收挤压固定螺钉重建ACL。术后对膝关节功能进行评定。结果：31例术后均未发生关节感染、血管神经损伤等严重并发症。30例获得随访，时间9-39个月，平均（19±9．0）个月，Lysholm膝关节功能评分从术前平均（54．6±16．6）分提高至随访时平均（92．5±5．7）分，较术前显著改善（t=11．84，P〈0．01）。30例患者中，26例恢复伤前运动水平，2例运动水平较伤前降低，2例因运动后出现关节酸痛而不敢剧烈运动。结论：关节镜下采用4股腘绳肌腱作移植物，生物可吸收挤压螺钉固定，是重建ACL的一种安全可靠的治疗方法。具有手术创伤少、术后膝关节功能恢复良好的优点。     

Mitek可吸收钉固定自体四股腘绳肌肌腱重建前交叉韧带21例

目的介绍关节镜下自体半腱肌,股薄肌移植重建前交叉韧带并利用Mitek可吸收钉固定的手术方法,观察其近期临床疗效。方法利用Mitek可吸收钉固定自体腘绳肌肌腱重建前交叉韧带21例。于术后3、6、12个月随访,分别进行Lyshol m功能评分和SF-36自我评分,以及Lachman和KT-2000客观体征评价,部分患者行MRI检查。结果21例全部获得随访,Lyshol m功能评分和SF-36评分较术前明显提高。2例Lachman征阳性,轴移试验均为阴性,KT-2000测试结果2例双侧差距超过5 mm。结论自体四股腘绳肌移植重建前交叉韧带可获得满意的临床效果,Mitek可吸收钉固定可提供良好的初始稳定,无排异反应,对MRI检查无影响。     

关节镜下采用四股和八股腘绳肌肌腱双束重建前十字韧带的比较研究

目的比较关节镜下采用四股和八股腘绳肌肌腱双束重建前十字韧带的临床效果。方法2001年9月至2002年8月,将76例陈旧性前十字韧带损伤患者随机分为两组进行双束重建。一组采用四股腘绳肌肌腱移植物:取同侧半腱肌肌腱,做成两个两股肌腱移植物,分别重建前十字韧带前、后束;一组采用八股腘绳肌肌腱移植物:取同侧半腱肌肌腱做成一个四股肌腱移植物重建前束,取同侧股薄肌肌腱做成另一个四股肌腱移植物重建后束。按照IKDC、Lysholm和Tegner膝关节评分标准评价疗效。结果四股肌腱移植物组有33例、八股肌腱移植物组有35例获得随访,随访时间1～3年,平均16个月。四股肌腱移植物组KT-1000检查示,双侧膝关节前向松弛度差异<3mm者25例(75.8%,25/33),3～5mm者5例(15.2%,5/33),6～10mm者3例(9.1%,3/33);轴移试验阴性28例(84.8%),阳性5例(15.2%)。八股肌腱移植物组KT-1000检查示,双侧膝关节前向松弛度差异<3mm者33例(94.3%,33/35),3～5mm者2例(5.7%,2/35);轴移试验阴性34例(97.1%),阳性1例(2.9%)。根据IKDC检查标准,四股肌腱移植物组有29例(87.9%,29/33)、八股肌腱移植物组有34例(97.1%,34/35)为正常或者接近正常,Lysholm评分分别为(90.2±2.9)分和(97.3±1.7)分,两组比较差异有统计学意义(P<0.05)。结论关节镜下采用八股腘绳肌肌腱较采用四股腘绳肌肌腱双束重建前十字韧带能够明显提高膝关节稳定性。     

三明治式后交叉韧带重建的初期临床结果

目的介绍三明治式后交叉韧带重建的方式，总结其初期临床结果。方法对18例陈旧性后交叉韧带断裂的患者在关节镜下采用8股胭绳肌肌腱、以保留后交叉韧带残留纤维的方式进行4隧道双束重建（三明治式后交叉韧带重建）。采用4股半腱肌肌腱重建前外侧束（主束），采用4股股薄肌肌腱重建后内侧束（副束）。移植物两端采用微型钢板纽扣进行悬吊式固定。随后对患者进行1年以上的随访。结果术前所有患者后抽屉试验阳性。术后1年，17位患者后抽屉试验阴性，KT-1000检查（屈膝90&#176;，30磅）双侧松弛度差异小于3mm。1位患者后抽屉试验1度阳性，KT-1000检查（屈膝90&#176;，30磅）双侧松弛度差异为4mm。根据IKDC评分标准，15位患者为正常，3为患者为接近正常。按照IKDC膝关节主观评分标准，结果从术前的64．1&#177;3．3改善至最近随访的93．5&#177;2．9（P〈0．01）。Lysholm评分从58．6&#177;4．4改善至94．3&#177;3．8（P〈0．01）。受伤前、术前和最近随访，Tegner评分分别为7．1，5．6和6．8。结论关节镜下采用8股胭绳肌肌腱以保留后交叉韧带残留纤维的方式进行4隧道双束重建能够可靠地恢复膝关节的稳定性。     

自体与同种异体腘绳肌腱重建前交叉韧带的疗效比较

目的 比较关节镜下保留残端自体腘绳肌腱与同种异体腘绳肌腱重建前交叉韧带的疗效。方法 将45例前交叉韧带损伤患者按照治疗方法不同分为观察组(采用关节镜下保留残端自体腘绳肌腱重建治疗，25例)和对照组(采用关节镜下保留残端同种异体腘绳肌腱重建治疗，20例)。比较两组膝关节稳定性、术后并发症发生率、膝关节功能及膝关节活动度。结果 患者均获得随访，时间12～14个月。术后12个月MRI检查显示两组均腱骨愈合。KT-2000关节测量仪测量的两组双侧移动差值：术后3个月比较差异无统计学意义(P>0.05),术后6、12个月观察组均小于对照组(P<0.05)。末次随访时，两组Lachman试验均为阴性。两组术后并发症发生率比较差异无统计学意义(P>0.05)。术后3、12个月Lysholm评分观察组均高于对照组(P<0.05)。末次随访时，两组膝关节伸直、屈曲活动度比较差异均无统计学意义(P>0.05)。结论 与同种异体腘绳肌腱相比，关节镜下保留残端自体腘绳肌腱重建前交叉韧带有利于膝关节功能的恢复，且稳定性好。     

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.