后路减压结合Dynesys动态内固定治疗腰椎退变性疾病的中期疗效

目的:评估后路减压结合Dynesys动态内固定治疗腰椎退变性疾病的中期疗效.方法:回顾分析2008年7月～2010年5月采用后路减压结合Dynesys动态内固定治疗的腰椎退变性疾病患者59例,其中腰椎管狭窄症38例,腰椎间盘突出症21例.记录患者术前、术后3个月及末次随访时Oswestry功能障碍指数(ODI)和疼痛视觉模拟量表(VAS)评分,测量术前、术后3个月及末次随访时手术节段活动度(ROM)、椎间高度及上位相邻节段ROM,评估上位相邻节段影像学和症状学退变的发生情况.结果:55例患者获得完整随访,随访48～70个月,平均54个月.术后3个月和末次随访时的ODI分别为(24.1±5.7)％和(15.9±6.3)％,均较术前的(56.3±16.4)％明显改善(P＜0.05).术后3个月和末次随访时的VAS评分分别为2.9±1.5和1.4±0.5,均较术前的6.7±2.7明显改善(P＜0.05).手术节段ROM由术前的(7.6±2.5)°保留至术后3个月的(4.5±2.8)°以及末次随访时的(4.9±2.3)°(P＜0.05).手术节段椎间高度在术后3个月为13.4±2.6mm,较术前12.3±2.7mm明显升高(P＜0.05);末次随访时为12.1±3.2mm,与术前差异无统计学意义(P＞0.05).上位相邻节段ROM由术前的(8.1±3.0)o增加至术后3个月的(9.3±3.2)°,至末次随访时达到(10.0±2.9)°(P＜0.05).末次随访时,7例(12.7％)患者出现上位相邻节段影像学退变,1例患者出现上位相邻节段症状学退变而接受二次Dynesys内固定手术.结论:后路减压结合Dynesys动态内固定能够获得良好的中期临床疗效.在中期随访时,Dynesys动态内固定能够保留手术节段部分活动度,存在一定程度的相邻节段退变.     

退变性腰椎滑脱症的手术治疗

目的探讨采用后路腰椎椎管减压、钉棒内固定并椎间植骨融合术和后路腰椎减压并Dynesys系统内固定手术治疗退变性腰椎滑脱的效果。方法应用后路腰椎椎间融合（posterior lumbar interbody fusion,PLIF）术进行椎管减压、钉棒系统固定并椎体间植骨融合手术治疗退变性腰椎滑脱37例;应用后路腰椎管减压并Dynesys内固定手术治疗退变性腰椎滑脱5例。结果随访9～39个月,平均26个月,腰痛疼痛视觉模拟量表（visual analogue scale,VAS）评分术前为8.7分,随访时为2.1分;腿痛VAS评分术前为7.6分,随访时为2.3分。术前Oswestry功能障碍指数（Oswestry disability index,ODI）为58.2%,随访时为21.2%。无严重手术并发症发生。术后X线片复查显示椎间高度均得到不同程度的恢复,滑脱椎体完全复位或者基本复位,椎间植骨融合。无融合器移位或螺钉松动、断裂。结论后路腰椎椎管减压、钉棒内固定并椎间植骨融合术和后路腰椎减压并Dynesys内固定手术治疗退变性腰椎滑脱效果满意,安全彻底的神经根管减压是取得满意临床效果的关键。     

Dynesys动态稳定系统治疗腰椎退变性疾病的短期疗效分析

目的：探讨Dynesys动态稳定系统在腰椎退变性疾病治疗中的短期临床疗效。方法29例腰椎退变性疾病患者在后路减压的同时行Dynesys动态稳定系统内固定术,评价术后疗效。结果术后临床疗效优23例（80%）、良4例（14%）,可2例（6%）。 VAS疼痛评分（0~10分）术前7.14±1.29分,末次随访时2.26±1.03分。术前病变脊柱运动节段过伸过屈活动度（ROM）7.51±2.68度,术后末次随访时ROM为4.22±1.47度。随访期间未见内固定松动和螺钉断裂现象。结论 Dynesys动态稳定内固定系统治疗腰椎退变性疾患具有手术操作简便、安全性高等优点,可减少对脊柱生理结构的破坏,维持节段稳定,减少远期腰椎退变和再次手术的风险,有很好的临床应用前景。     

减压结合Dynesys动态稳定治疗退行性腰椎管狭窄症

[目的]探讨减压结合Dynesys动态稳定系统治疗退行性腰椎管狭窄症的疗效和安全性。[方法]2007年1月～2008年6月,对23例退行性腰椎管狭窄症患者在后路减压后行Dynesys内固定术。[结果]随访(26.2±7.3)个月(17～34)个月,VAS评分:术前(8.2±0.9)分(6～10分),术后(2.2±1.3)分(0～5分)(P=0.001);Oswestry评分:术前(72.4±17.0)分(45～89分),术后(22.4±14.7)分(0～43分)(P=0.002)。无椎弓根螺钉松动、断裂。按中华医学会骨科学分会脊柱学组腰背痛手术评定标准评价:优17例,良4例,可2例,症状改善优良率达91.3%。[结论]减压结合Dynesys治疗退行性腰椎管狭窄症可取得良好的早期临床效果,防止固定及邻近节段的退变,是治疗腰椎退行性疾病的一种有效的非融合性、动力性固定方法。     

椎弓根内固定在退变性下腰椎疾患全椎板减压术中的应用价值

目的 探讨椎弓根内固定在退变性下腰椎疾患全椎板减压术中应用的中长期疗效及其安全性.方法 2002年5月至2005年5月,127例退变性下腰椎疾患患者行后路全椎板切除减压术(A组)及全椎板切除减压加后路椎弓根内固定术(B组),对临床资料进行回顾性分析,按照Oswestrydisability index评分标准设计问卷随访,对两种术式治疗退变性下腰椎疾患的临床效果进行评分并行统计分析.结果 全椎板减压患者共146例,截止2007年11月,127例获得随访,男70例,平均年龄(42.64±11.27)岁,女57例,平均年龄(44.37±11.96)岁,其中A组66例,B组61例,随访时间为30个月～66个月(平均为49个月).A、B两种术式优良率分别为77.27%、91.80%,两组间优良率比较P<0.05,二者疗效差异有统计学意义.结论 后路内固定系统为退变性下腰椎疾患全椎板减压提供稳定性支持,降低腰痛并发症,有利于充分减压从而缓解神经系统症状,明显提高下腰椎疾患全椎板减压患者的临床疗效,它也是一项安全的外科技术.     

退行性腰椎侧凸的手术治疗选择

[目的]探讨退行性腰椎侧凸手术治疗的选择,观察手术治疗的疗效。[方法]回顾分析2010年10月²013年05月,本院收治的26例经手术治疗的退变性腰椎侧凸病例,根据临床症状、体征和影像学资料,结合患者的身体条件和基础疾病,分别采用单纯减压,后路椎管减压、椎弓根螺钉内固定、椎间植骨融合术治疗退变性腰椎侧凸。观察患者术后症状缓解和功能改善情况。[结果]26例患者均获得随访,术后平均随访27.5个月(242013年05月,本院收治的26例经手术治疗的退变性腰椎侧凸病例,根据临床症状、体征和影像学资料,结合患者的身体条件和基础疾病,分别采用单纯减压,后路椎管减压、椎弓根螺钉内固定、椎间植骨融合术治疗退变性腰椎侧凸。观察患者术后症状缓解和功能改善情况。[结果]26例患者均获得随访,术后平均随访27.5个月(24⁴3个月),术后疼痛VAS评分和Oswestry功能障碍指数的改善率分别为(68.9±2.4)%和(80.5±4.1)%。侧凸平均矫正率(60.4±3.7)%,随访无断钉、断棒发生。[结论]对于退变性腰椎侧凸,应采取个体化治疗,严格掌握手术适应证,治疗以缓解患者症状为主要目的。     

Cosmic动态非融合系统治疗腰椎退变性疾病的短期疗效分析

目的探讨Cosmic动态非融合系统在腰椎退变性疾病治疗中的短期疗效。方法对22例腰椎退变性疾病在后路减压的同时行Cosmic动态非融合系统内固定术,并评价术后疗效。结果术后随访8~24个月,平均14.5个月,术后临床疗效优17例、良4例,可1例。VAS疼痛评分术前(6.74±0.59)分,末次随访时(2.13±0.61)分。术前病变脊柱运动节段过伸过屈活动度(ROM)(8.39±2.72)°,末次随访时为(8.17±2.58)°。随访期间未见内固定松动和螺钉断裂现象。结论采用Cosmic动态非融合内固定系统治疗腰椎退变性疾患具有手术操作简便、安全性高等优点,可减少对脊柱生理结构的破坏,维持节段稳定,减少远期腰椎退变和再次手术的风险,具有很好的临床应用前景。     

Dynesys动态固定系统治疗腰椎退变性疾病的临床疗效

目的探讨Dynesys动态固定系统应用于退变性腰椎疾病中的临床疗效评价。方法自2009-01—2013—01采用Dynesys动态固定系统结合后路椎板减压治疗35例腰椎退变性疾病,包括腰椎间盘突出症23例,腰椎管狭窄症12例。结果术后随访时间为6-40个月。平均26个月。术后3个月、1年和末次随访时的VAS及ODI均较术前明显下降。差异有统计学意义（P〈O．05）,而末次随访时较术后3个月和1年继续下降,差异有统计学意义（P〈0．05）。手术节段椎间隙后缘高度较术前明显增加,差异有统计学意义（P〈0．05）,但随时间的延长,高度略有下降,椎间隙前缘高度较术前减少,但差异无统计学意义（P〉0．05）。手术节段保持了一定的活动度,但较术前明显减少,差异有统计学意义（P〈0．05）。结论Dynesys动态固定系统结合椎板减压治疗腰椎退变性疾病的早期效果较明显。该手术方案维持了手术节段的椎间隙高度,在稳固脊柱的前提下保留一定活动度,能够预防邻近节段退变及腰椎不稳,但远期的疗效还需进一步深入研究。     

Dynesys治疗腰椎(L4、5)退变性疾病的早期临床疗效分析

目的 探讨Dynesys应用于腰椎(L4、5)退变性疾病的早期临床疗效及相关影像学改变.方法 自2008年8月～2009年12月,采用椎板开窗减压或部分切除,减压后置入Dynesys系统装置治疗12例腰椎退变性疾病.结果 术后随访14～28个月,ODI、VAS、JOA评分较术前明显改善(P＜0.05),L4、5节段椎体的活动度(ROM)术后与术前相比差异有统计学意义(P＜0.05).结论 Dynesys系统保留了腰椎生理曲度和固定节段的活动度,延缓并减少邻近节段的退变,短期临床疗效满意,其长期疗效有待进一步观察.     

Dynesys与后路减压融合内固定术治疗腰椎退行性疾病临床疗效的系统评价

目的:通过Meta分析评价Dynesys与后路减压融合内固定术治疗腰椎退行性疾病的有效性与安全性。方法:计算机检索Cochrane图书馆、Medline、Embase、CNKI、万方数据库和中国生物医学文献数据库,手工检索相关文献的参考文献及主要中英文骨科杂志。收集所有比较Dynesys和后路减压融合内固定术临床疗效与安全性的中、英文前瞻性或回顾性对照研究,评价纳入研究的方法学质量并提取资料,采用Cochrane协作网提供的Rev Man 5.2软件进行系统评价。结果:共纳入9项临床研究,其中3个前瞻性随机对照研究,6个回顾性对照观察研究。共692例患者,其中Dynesys组336例,后路减压融合内固定术组356例。Meta分析结果显示:与后路减压融合内固定术相比,Dynesys显著缩短了手术时间(P0.01)、减少了术中出血量(P0.01);与术前相比,在末次随访时二者均显著改善了患者ODI评分及腰腿痛VAS评分,差异无统计学意义(P0.05);Dynesys有效保留了固定节段部分活动度,但后路减压融合内固定术组患者邻近节段活动度的增加大于Dynesys组(P0.01);二者对于固定节段椎间高度的改善差异无统计学意义(P0.05),但后路减压融合内固定术具有较高的术后并发症发生率(P0.05)。结论:Dynesys和后路减压融合内固定术均是治疗腰椎退行性疾病的有效方式。与后路减压融合内固定术相比,Dynesys可以保留固定节段部分活动度,邻近节段活动度增幅及术后并发症发生率均较低,但其对于邻近节段退变的预防需要更多长期随访的前瞻性临床随机对照试验加以验证。     

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.