引导通道辅助下经皮椎弓根置钉与传统经皮椎弓根置钉的比较

目的 :比较引导通道辅助下经皮椎弓根置钉与传统透视下经皮椎弓根置钉的手术时间、射线暴露时间和置钉准确性。方法:70例无神经症状的胸腰椎骨折患者,随机分为A、B两组,A组35患者采用传统透视下经皮置入椎弓根螺钉,共置入180枚椎弓根螺钉;B组35例患者采用引导通道辅助下经皮置入椎弓根螺钉,共置入178枚椎弓根螺钉,均由同一术者完成置钉。记录两组椎弓根置钉时间、射线暴露时间,术后连续2次复查手术节段CT对两组病例置钉准确性进行评估并分级。比较两组患者单枚椎弓根螺钉置钉时间、射线暴露时间和置钉准确性。结果:两组患者年龄、体重指数、合并疾病、骨折类型、性别比例均无统计学差异(P0.05)。A组单枚椎弓根螺钉平均置钉时间为14.11±3.32min,B组为11.35±2.82min,两组比较差异有统计学意义(P=0.0042)。A组平均射线暴露时间为12.07±3.06s,B组为8.06±2.15s,两组比较差异有统计学意义(P=0.0031)。A组155枚(86.11%)螺钉为A级置钉,23枚螺钉(12.78%)为B级置钉,1枚螺钉(0.56%)为C级置钉,1枚螺钉(0.56%)为D级置钉;B组156枚螺钉(87.64%)为A级置钉,20枚螺钉(11.24%)为B级置钉,1枚螺钉(0.56%)为C级置钉,1枚螺钉(0.56%)为D级置钉,两组比较差异无统计学意义(P0.05)。结论 :引导通道辅助下经皮椎弓根置钉与传统经皮椎弓根置钉具有相同的准确性,但能明显减少置钉时间及辐射暴露时间。     

C臂机导航下经皮椎弓根钉内固定联合对侧微创TLIF治疗腰椎管狭窄症

目的 探讨导航辅助下经皮椎弓根钉内固定,联合对侧微创经椎间孔椎体间融合术(Transforaminal Lumbar Interbody Fusion,TLIF),治疗腰椎管狭窄症的临床应用.方法 2010年6月至2012年6月,对47例腰椎管狭窄症患者行导航下经皮椎弓根钉内固定,联合对侧微创TLIF术治疗,观察手术时间、出血量以及手术前后的VAS和ODI评分,并将经皮钉侧和开放置钉侧进行配伍对照比较.结果 平均出血量为(420±45) mL;术前VAS评分为(6.85±1.03),术后1月VAS评分为(1.88±0.79);术前ODI评分为(31.6±3.05),术后1月ODI评分为(43.1±3.23).配伍对照研究结果显示,经皮钉组A级101枚、B级9枚、C级2枚,开放置钉组A级86枚、B级21枚、C级4枚、D级1枚.经皮钉组平均置钉时间为(11.25±4.33) min,透视次数为(2.73±0.42)次,开放置钉组平均置钉时间为(15.43±5.65) min,透视次数为(4.12±0.85)次.差异均有统计学意义.结论 导航辅助下经皮椎弓根钉内固定,联合对侧微创TLIF治疗腰椎管狭窄症疗,效果显著,导航辅助下经皮钉组置钉术的准确度优于开放置钉组,透视次数和置钉时间均少于开放组.     

辅助经皮胸腰椎弓根螺钉置入激光定位仪在腰椎压缩性骨折手术中的应用

目的 探讨辅助经皮胸腰椎弓根螺钉置入激光定位仪(简称激光定位仪)在经皮椎弓根内固定术治疗单节段腰椎压缩性骨折中的可行性和临床应用.方法 前瞻性地纳入32例拟行经皮椎弓根螺钉内固定的单椎体腰椎压缩性骨折病人,随机分为两组,每组16例.观察组采用激光定位仪引导置钉,对照组采用正侧位透视置钉.记录并比较两组的置钉时间、辐射量...     

集中透视法在腰椎经皮椎弓根钉置钉术中的应用

目的评价集中透视法在腰椎经皮椎弓根钉置钉穿刺过程中减少X射线暴露的效果。方法纳入自2016-06-2017-07具有融合手术指征的50例腰椎退行性疾病,排除3个或3个以上节段融合者。25例经皮椎弓根穿刺时采用集中透视法(集中透视组),25例经皮椎弓根穿刺时采用单针透视法(单针透视组)。比较2组单节段融合与双节段融合患者穿刺透视次数及穿刺完成时间。结果 50例均顺利完成经皮椎弓根穿刺,未出现血管、神经损伤。在单节段融合与双节段融合患者中,集中透视组透视次数、穿刺完成时间均明显少于单针透视组,差异有统计学意义(P 0.05)。结论经皮椎弓根钉置钉穿刺过程中采用集中透视法可明显减少透视次数及穿刺时间,从而减少术者与患者的X线辐射量。     

微创椎弓根置钉技术治疗单纯胸腰段椎体骨折:Wiltse入路和经皮置钉的疗效及关节突关节损伤情况比较

目的 探讨Wiltse入路和经皮置钉技术治疗单纯胸腰段椎体骨折的临床疗效及关节突关节损伤的发生情况.方法 选取2016年1月～2019年12月本院行微创椎弓根置钉手术治疗的单纯胸腰段椎体骨折患者83例,按照手术方式不同分为两组:经Wiltse入路置钉者43例,纳入Wiltse组;经皮置钉者40例,纳入经皮置钉组.对两组患者的围手术期相关指标、关节突关节损伤情况和术后随访期间的疗效指标进行比较.结果 两组患者术中出血量、住院时间比较,差异均无统计学意义(P>0.05);Wiltse组的透视次数、手术时间显著少于经皮置钉组,差异有统计学意义(P<0.05).两组患者术后1 d、1个月和1年时的VAS评分、Cobb角比较,组间差异均无统计学意义(P>0.05).Wiltse组的伤椎复位率显著高于经皮置钉组,关节突关节损伤的发生率显著低于经皮置钉组,差异均有统计学意义(P<0.05).结论 两种微创术式均可取得良好的临床效果,Wiltse入路较经皮置钉具有更低的关节突关节损伤率和更稳定、良好的椎体复位率,临床中更值得推广、应用.     

引导通道辅助下经皮椎弓根置钉与传统透视下经皮置钉的临床对比

正笔者自2015-08-2016-08,开展了一项前瞻性分组对照研究,对80例行后路椎弓根钉内固定手术治疗的胸腰段单椎体骨折患者,分别利用引导通道辅助下经皮置钉36例、传统透视下经皮置钉44例,观察对比了两种置钉方式的差异性,现报告如下。1资料与方法1.1一般资料共纳入80例胸腰段单椎体骨折患者,采用随机数字表法将其分为观察组(在引导通道辅助下经皮置钉)36例和对照组(传统透视下     

经皮个体化导航模板辅助微创椎弓根螺钉内固定治疗胸腰椎骨折

目的评价经皮个体化导航模板(导板)辅助微创椎弓根螺钉内固定治疗胸腰椎骨折的安全性和有效性。方法将62例胸腰椎骨折患者按治疗方法分为两组:徒手透视组(32例)采用透视辅助下徒手经皮椎弓根螺钉内固定手术;经皮导板组(30例)采用术前模拟置钉,制作经皮3D打印个体化导板,术中辅助手术。比较两组术中出血量、手术时间、术中透视次数、切口长度、术后7 d和1个月的VAS评分;比较两组椎体前缘高度比、固定节段矢状曲度矫正度数、椎弓根皮质与螺钉关系、术中首次置钉准确率和矢状面螺钉置入角、同一椎体双侧螺钉矢状面夹角、螺钉进钉点水平位置差值、螺钉内倾角差值等。结果患者均获得随访,时间12~24个月。术中出血量、手术时间、透视次数经皮导板组均少于徒手透视组,差异均有统计学意义(P0.01)。两组术后椎体前缘高度比均较术前明显改善,差异有统计学意义(P0.01);术后即刻与末次随访时椎体前缘高度比、固定节段矢状曲度矫正度、螺钉首次置钉成功数、矢状面螺钉置入角经皮导板组均优于徒手透视组,差异均有统计学意义(P0.01)。双侧螺钉矢状面夹角、螺钉进钉点水平位置差值、螺钉内倾角差值经皮导板组均小于徒手透视组,差异均有统计学意义(P0.05)。结论经皮导板辅助的椎弓根螺钉技术能简化手术,具有操作减少射线暴露、手术时间短、定位准确、装配简单、骨折复位好等优点。     

经皮枢椎椎弓根螺钉内固定的影像学研究

目的根据枢椎椎弓根影像学测量数据探讨实施经皮穿刺枢椎椎弓根螺钉内固定的可行性与安全性。方法测量40名正常成人中立位寰枢椎二维CT水平位及矢状位断层图像上枢椎椎弓根螺钉经皮置人的标准角度及置钉角度的安全范围，皮肤穿刺点与水平位上颈后中线距离和矢状位上枢椎基底前缘顶点皮肤投影点的标准距离及其安全范围等影像学参数。结果（1）水平位枢椎椎弓根螺钉置钉的标准角度为42．34±2．95度．其安全范围为13．68±2．17度；（2）矢状位上椎弓根螺钉置钉的标准角度为27．94±3．98度，安全范围为19．39±2．19度；（3）水平位上皮肤穿刺点与颈后中线标准距离为57．39±7．47mm．安全范围为19．46±3．48mm；（4）矢状位上皮肤穿刺点与枢椎基底前缘顶点皮肤投影点的标准距离为36．50±4．62mm．其安全范围为37．35±4．96mm。结论枢椎椎弓根螺钉经皮置人的标准角度及距离个体差异较大，但在水平面和矢状面上均有一定的安全范围．该手术在充分考虑个体差异情况下具有一定安全性和可操作性。     

数字化胸椎椎弓根导向模板的设计及其临床应用研究

目的采用数字骨科技术设计并制作胸椎椎弓根导向模板,评价其在胸椎骨折椎弓根钉内固定术中的临床应用价值。方法选取自2013-01—2015-02行胸椎椎弓根钉内固定的5例单椎体骨折,术前根据CT三维重建扫描所得的数据,借助医学影像控制系统Mimics 17.0软件重建伤椎三维数字模型,并根据三维空间内的椎体骨折情况,利用Unigraphics NX 9.0工程软件设计具有椎弓根钉最佳进钉通道且与置钉椎体三维互补的导向模板。通过快速成型技术制作胸椎椎弓根导向模板及椎体,并在术中通过椎弓根导向模板与椎体后侧结构的精确贴合,按照预先设计的置钉通道置钉,术后复查CT评价螺钉位置。结果 5例均顺利完成椎弓根钉置钉操作,共置入30枚椎弓根钉,置入螺钉长度为30~45 mm,直径为5.0~7.0 mm。按改良置钉分级标准评定椎弓根钉置入结果:Ⅰ级19枚,Ⅱ级9枚,Ⅲ级2枚。所有患者均获得12~24(13.00±4.12)个月随访,未发现与置钉相关的神经根、脊髓等损伤症状,无螺钉松动、退出、断裂。结论胸椎骨折内固定术中采用数字化椎弓根导向模板辅助椎弓根钉置入较传统置钉方法有更快速、安全和精确的优势。     

球形探针技术在胸腰椎椎弓根螺钉置钉中的应用

目的通过与传统开路锥置钉技术比较,评价在胸腰椎椎弓根螺钉置钉中应用球形探针技术的准确性和安全性,探讨其临床应用价值。方法回顾性分析2016年1月—2017年2月新疆医科大学第一附属医院收治的需行胸腰椎椎弓根螺钉内固定治疗的106例患者临床资料,术中应用球形探针技术或传统开路锥技术置入椎弓根螺钉。其中56例采用直径2.5 mm球形探针穿刺(球形探针组),其余50例采用传统开路锥穿刺(传统组)。术后采用CT检查确认螺钉位置以评估置钉准确性。结果球形探针组共置入椎弓根螺钉296枚,传统组共置入264枚。术后CT显示球形探针组置钉准确率为97.64%,7枚置钉不良;传统组置钉准确率为83.71%,43枚置钉不良。2组置钉准确率及穿透椎弓根内侧、椎弓根外侧、椎体前壁骨皮质螺钉比例差异均有统计学意义(P<0.05)。2组术中出血量间差异无统计学意义(P>0.05)。传统组术后1例出现L5神经根损伤致足下垂;球形探针组术中、术后均未出现神经、血管、脑脊液漏或内脏损伤等并发症。结论与传统开路锥置钉技术相比,球形探针技术能更准确置入胸腰椎椎弓根螺钉,减少因螺钉位置不良导致的并发症。     

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.