复合骨移植在下肢骨肿瘤保肢治疗中的应用

目的探讨复合骨移植在下肢骨肿瘤保肢术中重建骨缺损的手术原理及效果。方法应用携带监测皮岛吻合血管的自体腓骨与深低温冷冻大段同种异体骨复合移植，重建下肢骨肿瘤切除后的长段骨缺损12例。其中，骨肉瘤6例，恶性纤维组织细胞瘤1例，骨纤维结构不良2例，骨巨细胞瘤3例。结果12例经术后8～38个月随访，1例死于肺转移，2例带瘤存活，9例无瘤存活。术后功能优良率达75％。10例术后3个月内X线示骨端骨性愈合，2例内固定失败重新外固定后骨性愈合，所有均在9个月内能完全负重行走。结论携带监测皮岛吻合血管的自体腓骨与深低温冷冻大段同种异体骨复合移植，适用于下肢骨肿瘤保肢术中的长段骨缺损的修复，具有自体活骨移植和异体骨移植的双重优点。     

下肢远端原发恶性骨肿瘤患者的生存和肢体功能分析

目的 分析下肢远端原发恶性骨肿瘤患者的生存情况,评估保肢后的肢体功能.方法 2003年11月至2010年1月,20例下肢肢体远端原发恶性骨肿瘤接受保肢或截肢手术.男性15例,女性5例,平均年龄20岁.肿瘤位置:胫骨远端14例,腓骨远端3例,跟骨3例.肿瘤分期:ⅠB期3例,ⅡB期16例,Ⅲ期1例.除3例胫骨下端肿瘤截肢外,其他11例胫骨远端肿瘤行自体骨(4例)或异体骨(7例)踝关节融合手术,6例腓骨远端和跟骨肿瘤行自体骨重建手术.平均随访36.4个月.结果 5例异体骨踝关节融合和1例跟骨自体骨重建患者伤口延迟愈合,自体骨和异体骨对伤口愈合的影响差异有统计学意义(P=0.036).2例异体骨出现吸收和不愈合(其中1例截肢,另1例更换为骨水泥临时假体),1例胫骨远端骨肉瘤术后11个月复发截肢,2例分别于确诊后22和48个月死于肺转移.患者2和5年的总生存率分别为92.9%和79.6%,12例高度恶性骨肉瘤的2和5年生存率分别为87.5%和70.0%.保肢患者功能MSTS评分为82%.结论 下肢肢体远端原发恶性骨肿瘤的整体生存情况相对较好,保肢可以获得良好的肿瘤控制和肢体功能.     

大段异体骨移植治疗骨肿瘤

目的 探讨大段异体骨移植在骨肿瘤保肢治疗中的临床疗效。方法 回顾观察了 1991年 9月～ 1998年 10月,应用大段异体骨修复 79例骨肿瘤患者瘤段骨切除后骨缺损的治疗情况。男 55例,女 24例;年龄 9～ 70岁,平均 28.8岁。骨肉瘤 38例,恶性骨巨细胞瘤 12例,其他肿瘤 29例。骨段移植 24例,半关节移植 50例,复合人工关节移植 5例。植入异体骨长度 8～ 22 cm,平均 13.5 cm。非交锁型髓内钉固定 16例,交锁型髓内钉固定 53例,钢板固定 5例,复合人工关节移植 5例。结果 67例患者得到随访,时间 5个月～ 7年,平均 2.8年,结果异体骨愈合 62例,不愈合 5例。主要并发症 :复发 8例,感染 8例,骨不连 5例,骨折 4例,内固定失败 4例,关节面吸收塌陷 7例。功能按 Mankin标准评定 :优 25例,良 23例,中 11例,差 8例。结论 大段异体骨移植是一种修复骨肿瘤瘤段切除后骨缺损的有效手段;牢固的髓内固定有利于异体骨愈合。     

骨肿瘤

20061286 复合骨移植在下肢骨肿瘤保肢治疗中的应用／王建炜…∥中华显微外科杂志．-2005，28（4）．-309-311 应用携带监测皮岛吻合血管的自体腓骨与深低温冷冻大段同种异体骨复合移植，重建下肢骨肿瘤切除后的长段骨缺损12例。其中，骨肉瘤6例，恶性纤维组织细胞瘤1例，骨纤维结构不良2例，骨巨细胞瘤3例。结果：12例经术后8～38个月随访，1例死于肺转移，2例带瘤存活，9例无瘤存活。术后功能优良率达75％。10例术后3个月内X线示骨端骨性愈合，2例内固定失败重新外固定后骨性愈合，所有均在9个月内能完全负重行走。结论；携带监测皮岛吻合血管的自体腓骨与深低温冷冻大段同种异体骨复合移植，适用于下肢骨肿瘤保肢术中的长段骨缺损的修复，具有自体活骨移植和异体骨移植的双重优点。图3参6     

大段同种异体骨修复骨肿瘤手术后缺损研究进展

大段同种异体骨移植重建肢体功能已成为骨肿瘤保肢手术的重要方法。根据肿瘤类型确定手术切除边界,在保证肿瘤完整切除的前提下重建患肢功能,术中辅以坚强的内固定对大段同种异体骨移植后骨愈合至关重要。大段同种异体骨移植的骨愈合机制主要为激活骨诱导及骨传导,体现在受体逐渐爬行替代异体骨的缓慢过程。异体骨缓慢愈合过程中感染、异体骨骨折及骨不愈合等并发症发生率较高,影响了大段同种异体骨移植治疗的效果。该文就骨肿瘤保肢手术中大段同种异体骨移植手术方法、并发症防治方面的研究进展作一综述。     

四肢恶性骨肿瘤功能重建后的并发症防治

目的分析四肢恶性骨肿瘤功能重建后并发症的发生原因与防治。方法自2002年9月至2004年12月共有22例患者接受保肢治疗。年龄10～63岁，平均26.3岁。男10例，女12例。其中骨肉瘤15例，恶性骨巨细胞瘤2例，软骨肉瘤5例。15例骨肉瘤患者术前均接受了2～3次化疗。待伤口愈合后再接受5～6次化疗。肿瘤部位：胫骨近端5例，股骨远端12例，股骨近端1例，股骨中段2例，肱骨近端2例。手术方法为局部肿瘤完整切除，大段异体骨移植术、人工假体重建术和肿瘤灭活再植术。其中10例行人工假体重建术，10例行大段异体骨移植术，2例行肿瘤灭活再植术。结果随访7～27个月，3例骨肉瘤患者术后局部复发，复发时间分别为术后3个月、7个月、1年，后行截肢术。1例患者术后3个月出现肺转移，经化疗后肺部肿块消失；2例大段异体骨移植术患者术后出现排斥反应，伤口不愈伴感染，后经清创、腓肠肌肌皮瓣转移术后愈合。1例人工假体重建术后2周，伤口出现渗液，后经局部换药后愈合。结论恶性骨肿瘤采取保肢的术后并发症与适应证的选择、肿瘤对化疗的敏感性、瘤体切除的方式、功能重建选择的方法等都有密切的关系。因此，在对恶性肿瘤采取保肢手术治疗时，必须综合考虑上述因素，才能减少并发症的发生。     

大段异体骨移植后骨端不愈合的外科治疗

目的 探讨应用自体骨植骨再固定的方法治疗大段同种异体骨移植后骨端不愈合的手术方法和疗效.方法 1994年1月至2006年12月北京积水潭医院所行大段同种异体骨移植患者176例中41例不愈合,22例进行了骨接触端的重新植骨治疗,其中15例临床资料完整.再植骨治疗时年龄15～34岁,平均为24岁.初始疾病为:骨肉瘤5例、骨巨细胞瘤4例、皮质旁骨肉瘤2例、血管内皮瘤2例、骨原始神经外胚瘤(PNET)2例.发病部位:股骨下端7例、肱骨中段3例、股骨中段2例、胫骨上端2例、肱骨上端1例.15例患者中,8例单纯不愈合行植骨术,另7例不愈合并发原内固定断裂行植骨和再固定手术.结果 随访时间18～148个月,平均47个月.15例中13例骨愈合,占86.7%.愈合时间5～20个月,平均13个月.其中8例无原内固定失败者均重新愈合,愈合时间平均为14个月.另7例原内固定失败者5例重新愈合,愈合时间平均为12个月,与上述8例比较愈合时间相似.无感染等并发症发生.2例仍不愈合,最终行人工假体置换术.13例骨愈合的患者MSTS评分平均25.1分,8例无原内固定失败者25.4分,5例原内固定失败者24.6分,评分基本相同.结论 应用自体骨植骨再固定的方法治疗大段异体骨移植后骨端不愈合手术简单,并发症少,愈合率高,再手术后功能影响小,较人工假体置换相比有明显优势,对于大段异体骨移植后骨端不愈合患者,应为首选治疗方法.     

同种异体骨移植后的病理组织学观察

目的探讨同种异体骨移植后骨修复的生物学过程和病理组织学变化。方法收集自2002年2月-2004年3月因临床并发症取出的异体骨标本5例及因大段异体骨移植后不愈合再次植骨手术中活检病例2例，共7例。骨肿瘤4例，其中肱骨近端恶性纤维组织细胞瘤行肿瘤切除大段异体骨移植髓内钉内固定术1例，股骨干骨肉瘤行肿瘤段切除大段异体骨移植1例，股骨远端骨巨细胞瘤行肿瘤切除股骨远端大段异体骨移植钢板内固定术1例，胫骨近端巨细胞瘤行肿瘤切除大段异体骨移植钢板内固定术1例。创伤3例，其中2例为左股骨远端开放粉碎性骨折行大段异体骨移植骨不愈合切开取内固定植骨、外固定架固定术，同时对大段异体皮质骨取材活检；1例为胫骨中段开放性骨折，行钢板固定异体松质骨移植术，术后感染。结果通过观察骨吸收的病理组织学特点发现骨吸收主要集中在5例病例中，其临床特点可以归纳为：(1)X线片所示有严重的骨吸收，无伤口问题；(2)X线片显示有骨吸收伴有窦道、渗出；(3)伤口化脓。后者可以认为是骨组织的化脓性感染引起的骨吸收，前两种情况骨吸收可以分为：一是破骨细胞性骨吸收，常伴有新骨形成；二是炎症性骨吸收，吸收部位有较多的慢性炎性细胞，骨表面缺乏破骨细胞和成骨细胞，无新骨形成。3例有明显骨吸收者可以观察到血管内皮细胞增生、官腔闭塞。结论破骨细胞骨吸收是机体对异体骨修复和骨重建的过程。炎症性骨吸收的出现是异体骨移植中的不良组织学反应；如出现血管病变表示排斥反应重，异体骨移植可能失败。     

同种异体半关节移植治疗股骨远端肿瘤

目的 对大段异体骨移植用于骨肿瘤保肢治疗及其相关问题进行分析讨论。方法采用大段异体骨修复骨肿瘤瘤段切除后骨缺损5例，术后X线及同位素骨扫描评定骨愈合，并评估其功能恢复情况。结果手术后3—6个月在X线片显示牢固的生物固定（坚强的外骨痂或已骨性连接）、^99mTc—MDP骨扫描图像显示异体骨早期代谢活跃，2年后逐渐恢复正常。结论 同种异体骨半关节移植治疗股骨远端肿瘤术后观察移植骨与自体骨愈合，关节功能重建方面到达良好表现。     

同种异体骨复合人工关节治疗股骨肿瘤的研究

目的探讨应用同种异体骨复合人工关节对股骨肿瘤切除后骨缺损的治疗.方法自1996年12月至2004年12月,采用同种异体骨复合人工关节治疗股骨肿瘤20 例,其中复合股骨上端的全髋关节置换8 例,复合股骨下端全膝关节置换12 例.按Enneking分期,广泛边缘性切除肿瘤,选用长柄人工关节和形态合适的同种异体骨与宿主骨经骨水泥髓内固定,假体柄插入宿主骨髓内长度与异体骨轴心长度比应为0.8以上.术后均未使用免疫抑制剂.结果 20 例中随访18 例,平均36个月.2 例骨肉瘤患者术后15个月内死亡,其余患者均无瘤生存.所有患者均无关节脱位、假体松动和断裂.16 例异体骨和宿主骨形成骨性融合,融合时间为6～12个月,平均8个月.8 例股骨上端的全髋关节置换者,髋关节的主动活动度为70°～120°,平均83°;10 例复合股骨下端全膝关节置换者,膝关节的主动活动度为67°～130°,平均90°.按ISOLS骨肿瘤术后功能重建评分为21～29分,平均27.5分.结论异体骨与宿主骨间的生物连接增加了人工关节的固定臂,从而降低了假体松动、下沉或断裂的发生率.同种异体骨移植复合人工关节置换具有异体骨和人工关节两者的优点,更适合良性和生存时间较长的恶性肿瘤的保肢治疗.     

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.