尿毒症患者血清脂联素与慢性炎症状态的临床意义研究

目的：通过检测尿毒症患者血清脂联素与体内炎症指标的水平,分析血清脂联素与体内炎症反应的关系,探讨血清脂联素对心血管疾病影响的机制。方法：在本实验中,采用ELISA方法测定60例尿毒症患者的血清脂联素（adiponectin,ADPN）水平,炎症指标血C-反应蛋白（C-reactive protein,CRP）,肿瘤坏死因子（tumor necrosis factor,TNF-α）,纤维蛋白原（fibrinogen,Fbg）,并分析血清脂联素与炎症指标、颈动脉斑块的关系。结果：在所有研究对象中有46.7%的患者CRP水平超过正常参考值5 mg/L。在实验组中血ADPN、TNF-α、Fbg均高于健康对照组（P值均〈0.05）并且单因素相关分析结果表明血ADPN与CRP、TNF-α、Fbg均呈明显负相关,相关系数分别为-0.49、-0.51、-0.43（P值均〈0.01）。有颈动脉粥样斑块患者血清显著降低（11.23±4.92）μg/ml与无颈动脉粥样斑块患者血清ADPN（15.71±4.68）μg/ml相比差异有统计学意义（P〈0.01）。结论：在尿毒症患者中,血清脂联素水平与体内炎症反应密切相关,脂联素可能是一种负性炎症因子并具有心血管系统的保护作用。     

维持性腹膜透析患者中医证型与脂联素的关系

目的:探讨维持性腹膜透析(PD)患者中医证型与脂联素(ADPN)的相关性。方法:研究对象来源于杭州市中医院腹透门诊常规PD患者,入选患者随访2年,分别进行中医辨证分型,检测血清脂联素(ADPN)、三酰甘油(TG)、总胆固醇(TC)、高密度脂蛋白(HDL)、低密度脂蛋白(LDL),血白蛋白(Alb)、血红蛋白(Hb)等指标,探讨中医证型分布比例及演变,并分析其与上述指标的相关性。结果:(1)中医本证以气虚证、肾阳虚证为主,分别占43. 2%、27. 8%,无兼证占58%,湿浊证为33%,血瘀证为9%。(2)肾阳虚证组ADPN水平较低,无兼证组ADPN水平较高。(3)腹透时长与脂联素水平呈负相关,与TG水平呈正相关。(4)证型演变主要以气虚证转变为肾阳虚证、无兼证转变为湿浊证为主。结论:PD患者的中医证型以气虚证、肾阳虚证、无兼证为主,随着腹透时间延长,呈气虚证转变为肾阳虚证、无兼证转变为湿浊证趋势。ADPN与肾阳虚相关。     

2型糖尿病患者血清SFRP5、脂联素水平与尿蛋白的关系临床研究

<正>脂联素(adiponectin,ADPN)是一种抗炎脂肪因子,且其具有改善胰岛素抵抗及抗动脉粥样硬化等作用。分泌型卷曲相关蛋白-5(Secreted frizzled-related protein 5,SFRP5)被证实是继脂联素之后的又一抗炎脂肪因子,其可能通过炎症反应参与肥胖及糖尿病等代谢性疾病的发生[1]。目前,关于SFRP5与糖尿病微血管病变的研究少见报道。本研究通过测定糖尿病患者血清SFRP5、ADPN水平变化,探讨2型糖尿病患者血清SFRP5和ADPN水平与UAER的相关性及血清SFRP5和ADPN水平是否可以作为糖尿病肾病早期预测指标。     

维持性血液透析患者微炎症与动脉粥样硬化的关系

目的 探讨维持性血液透析患者微炎症与动脉粥样硬化的关系.方法 测定40例经透析充分的维持性血液透析患者透析前血肌酐、血尿酸、血糖、血浆白蛋白、甘油三酯、胆固醇、C反应蛋白、白细胞介素6、肿瘤坏死因子α.应用超声测定颈动脉中层厚度及有无颈动脉斑块形成.结果 两组患者在年龄、性别构成、血脂、血糖、血尿酸水平比较差异无统计学意义(P＞0.05)的前提下,动脉粥样硬化组患者C反应蛋白、白细胞介素6及肿瘤坏死因子α与非动脉粥样硬化组患者比较差异有统计学意义(P＜0.05).结论 微炎症参与了维持性血液透析患者动脉粥样硬化的形成.     

终末期肾病微炎症状态和动脉粥样硬化的关系

目的研究终末期肾病(ESRD)的微炎症状态与动脉粥样硬化的关系。方法以246例ESRD患者和肾功能正常的对照组43例为对象,监测其有关炎症因子和颈动脉B超指标,分析尿毒症微炎症状态及其与动脉粥样硬化的关系。结果ESRD患者血清中炎症性指标C反应蛋白(CRP)、白介素(IL)-6和肿瘤坏死因子(TNF)-α等的平均水平虽在正常范围内,但明显高于对照组。根据CRP水平分组后发现,CRP>4mg/L组在颈动脉B超各项指标和心脑血管事件发生率等方面与CRP<4mg/L组相比,差异有显著性意义。根据有无动脉粥样硬化心脑血管病史而分组后发现,阳性组患者血清中CRP、IL-6和TNF-α水平虽在正常范围内,但仍显著高于阴性组患者。结论尿毒症患者体内存在微炎症状态,这种微炎症状态可能是引起尿毒症高发动脉粥样硬化性心脑血管事件的独立危险因素之一。     

尿毒症血液透析患者血清脂联素与炎症标志物的关系

目的：探讨尿毒症血液透析患者血清脂联素（adiponectin）水平的变化；了解血液透析患者炎症标志物血清C反应蛋白（CRP）、血浆纤维蛋白原（Fbg）水平的变化以及脂联素与炎症标志物的关系。分析脂联素对炎症、血脂、动脉粥样硬化的影响。方法：应用ELISA法测定30例体检健康者与76例慢性肾衰竭尿毒症血液透析患者血清脂联素的水平；免疫比浊法测定血清CRP、凝固法测定血浆Fbg水平。结果：尿毒症组患者血脂联素CRP、Fbg水平明显高于健康对照组（P〈O．05或P〈0．01）。尿毒症患者血清脂联素与CRP、Fbg、体重指数（BMI）呈负相关，相关系数r分别为-0．50、-0．37、-0．34（P〈0．05或P〈0．01）。将尿毒症组依据cRP水平分为A、B两组，A组CRP〈5mg／L，B组CRP〉5mg／L。A组脂联素水平明显高于B组（P〈0．05）。结论：尿毒症血液透析患者体内存在微炎症状态。脂联素通过减轻炎症反应对尿毒症血液透析患者具有保护作用。     

高纯度透析浓缩液对血液透析患者血清白细胞介素6、肿瘤坏死因子α和白蛋白水平的影响

目的比较高纯度透析浓缩液和普通透析浓缩液对长期透析患者血清促炎症因子白细胞介素(6IL鄄6)、肿瘤坏死因子α(TNF鄄α)和血清白蛋白的影响。方法采用前瞻性临床对照研究,将85例维持性血液透析患者随机分为两组,分别采用普通透析浓缩液(常规组,例)和42高纯度透析浓缩液(高纯度组,例)进行常规低通量血液透析治疗并随访4312个。月比较常规组与高纯度组患者在血清IL鄄6、TNF鄄α、血清白蛋白、干体重、体重指数(BMI)、上臂中肌肉周径(MAC)、血红蛋白、红细胞压积、白细胞计数、中性粒细胞计数以及红细胞生成素应用剂量上的差异。结果高纯度组43例,常规组42例,两组患者间年龄、性别比例、透析龄、BMI、Kt/V值和血清IL鄄6、TNF鄄α水平差异无统计学意义。与基础水平比较,随访结束时高纯度组患者血清IL鄄6[(6.91±5.13)pg/ml比(3.06±2.42)pg/ml]和TNF鄄α水平[(14.78±4.61)pg/ml比(13.60±4.24)pg/ml]显著下降;血清白蛋白[(35.9±3.7)g/L比(37.6±3.4)g/L]、血红蛋白[(82.4±24.7)g/L比(88.2±22.9)g/L]及红细胞压积(0.25±0.07比0.28±0.05)均显著上升。与常规组比较,随访结束时高纯度组血清IL鄄6[(3.06±2.42)pg/ml比(4.22±3.99)pg/ml]和TNF鄄α水平[(13.60±4.24)pg/ml比(15.79±6.38)pg/ml均显著下降     

维持性血液透析患者血清脂联素与左心室肥厚的相关性分析

目的探讨维持性血液透析（MHD）患者血清脂联素（ADPN）水平与左心室肥厚（LVH）的相关性。方法选择我院MHD患者79例,行心脏超声心动图测定左心室舒张末期内径（LVDd）、左心室收缩末期内径（LVDs）、室间隔厚度（IVST）、左心室后壁厚度（LVPwT）、左心室射血分数（EF）,计算左心室质量指数（LVMI）。按照LVMI值将79例MHD患者分成LVH组和非LVH组,选择同期健康者16名为对照组。测定3组血清ADPN、血糖、胰岛素、血脂、C反应蛋白（CRP）,计算体重指数（BMI）、稳态模型胰岛素抵抗指数,分析血液透析患者血清ADPN水平与上述参数及LVH之间的相关性。结果LVH组和非LVH组的血清ADPN均高于对照组,LVH组血清ADPN低于非LVH组,而胰岛素、胰岛素抵抗指数、CRP高于对照组和非LVH组;MHD患者血清ADPN与胰岛素、胰岛素抵抗指数、CRP、LVMI呈明显负相关,胰岛素抵抗指数、CRP与LVMI呈明显正相关。结论MHD患者血清ADPN水平与慢性炎症及胰岛素抵抗关系密切,可能共同参与了LVH的发生和发展。     

血液透析患者血清铁调素与颈动脉粥样硬化的关系

目的:探讨维持性血液透析(MHD)患者血清铁调素(hepcidin)水平的变化及与颈动脉粥样硬化的相关性。方法:选择维持性血液透析患者93例和健康对照组40例为研究对象,采用ELISA法测定hepcidin、IL-6及TNF-α水平,高分辨二维超声对双侧颈总动脉内膜中膜厚度(IMT)及颈动脉粥样斑块进行测量,分析hepcidin水平与颈动脉病变及炎症因子之间的关系。结果:MHD组患者血清hepcidin水平(139.04±77.91)μg/L显著高于健康对照组(51.13±22.01)μg/L;MHD组CRP、IL-6、TNF-α水平均显著高于健康对照组(P0.05或P0.01)。MHD组IMT值为(1.15±0.21)mm、斑块形成率(59.2%)、颈动脉硬化的患病率(77.6%)均显著高于健康对照组的(0.78±0.28)mm和2.5%与10%(均P0.05)。直线相关分析显示MHD组血清hepcidin水平与CRP、IL-6、TNF-α、IMT及斑块形成、颈动脉硬化率的患病率均呈正相关;与SBP、DBP、年龄亦呈正相关(P0.05或P0.01)。多元逐步回归分析显示,hepcidin、CRP、SBP和年龄是MHD颈动脉病变的独立危险因素。结论:MHD患者血清hepcidin水平显著升高,其可能通过促进CRP、IL-6等炎症因子的产生,参与MHD患者动脉粥样硬化的形成。     

微炎症状态与尿毒症并发症的关系

目的:探讨微炎症状态与尿毒症并发症贫血、营养不良、动脉粥样硬化性心脑血管疾病(CVD)之间的关系.方法:检测75例尿毒症患者血清C反应蛋白(CRP)、血红蛋白(Hb)、血浆白蛋白(Alb)、血肌酐(Scr)、颈动脉B超指标和CVD发生率;分析微炎症状态与尿毒症并发症的关系.结果:尿毒症透析组与非透析组CRP均在正常范围内,但明显高于肾功能正常的对照组(P＜0.01),且透析组又高于非透析组(P＜0.05).透析组与非透析组在贫血、营养不良、CVD等方面有统计学差异(P＜0.05),且CRP与Hb、Alb呈负相关,与CVD、颈总动脉内膜-中层厚度(intima-mediathickness,IMT)呈正相关.尿毒症合并动脉粥样硬化性CVD阳性组,CRP升高,Hb、Alb降低,与阴性组比较有统计学差异(P＜0.01),但仍然在正常范围内.结论:微炎症状态参与了尿毒症并发症贫血、营养不良、动脉粥样硬化性心脑血管疾病的发生与发展.     

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.