后外侧联合后内侧入路治疗胫骨平台后柱骨折的临床研究

目的观察后外侧联合后内侧入路治疗胫骨平台后柱骨折手术方法及临床疗效。方法对13例胫骨平台后柱骨折采用后外侧联合后内侧入路切开复位内固定术进行治疗。比较术后即刻、12个月的胫骨平台内翻角(TPA)、胫骨平台后倾角(PA)。采用HSS膝关节评分及膝关节活动度(ROM)评价术后疗效。结果本组均获12~20个月随访,骨折全部愈合,术后12个月HSS膝关节评分73~92分,平均(82.4±6.8)分,ROM平均为(121.6±1.2)°。术后即刻与12个月TPA、PA度数差异均无统计学意义(P>0.05)。结论后内侧联合后外侧入路可治疗广泛而复杂的胫骨平台后柱骨折,采用双切口对于后内侧和后外侧骨折复位和固定都较充分,对软组织创伤较小,利于关节功能恢复。     

改良前外侧入路锁定钢板内固定治疗孤立性后外侧胫骨平台骨折疗效分析

目的探讨改良前外侧入路锁定钢板内固定治疗孤立性后外侧胫骨平台骨折的临床疗效。方法回顾性分析自2015-01—2018-04采用改良前外侧入路锁定钢板内固定治疗的23例孤立性后外侧胫骨平台骨折。末次随访时采用HSS评分标准评价膝关节功能。结果 23例均获得随访,随访时间平均15.4(12～23)个月。骨折均骨性愈合,骨折愈合时间平均12(10～16)周。术后骨折复位情况根据Rasmussen评分标准评定:优17例,良6例。术后1年随访时均未见明显关节面复位丢失。术后即刻X线片测量胫骨平台内翻角为(87.3±0.5)°,术后1年为(87.7±1.2)°。术后即刻X线片测量胫骨平台后倾角为(7.3±0.7)°,术后1年为(7.5±1.2)°。术后1年随访时膝关节活动度平均125.5°(105°～135°)。末次随访时膝关节功能HSS评分:优12例,良9例,可2例。结论采用改良前外侧入路锁定钢板内固定治疗孤立性后外侧胫骨平台骨折可清晰地显露骨折部位并完成有效固定,较好地维持膝关节稳定性,有利于患者术后早期功能锻炼。     

前后联合入路治疗累及后外侧平台劈裂C型胫骨平台骨折

目的 探讨前后联合入路治疗累及后外侧平台劈裂C型胫骨平台骨折的手术方法及临床疗效.方法 7例患者术前均经CT扫描及三维重建,均采用后路和前外侧联合入路后侧和前外侧支撑钢板固定.采用DeCoster评定标准评定骨折复位情况、测定胫骨平台内翻角和采用HSS法行膝关节功能评定.结果 术后X线片检查示达到解剖复位5例,复位良好1例,差1例.1例发生膝内翻.7例均获随访,时间6～18(12±6)个月.骨折全部愈合,愈合时间14～16(15±1)周.胫骨平台内翻角术后1年和术后初次摄片无变化;膝关节功能HSS评分为78～90(80±4)分.结论 前后联合入路并后侧入路支撑钢板固定是治疗累及后外侧孤立劈裂C型胫骨平台骨折的有效方法.     

胫骨平台后柱骨折不同手术径路内固定的疗效分析

目的探讨胫骨平台后柱骨折的手术方式,分析比较应用不同手术径路内固定的疗效。方法手术治疗胫骨平台后柱骨折29例,其中采用后内侧、前侧联合入路10例(posteromedial plus anterior approach,PMA组),前侧入路19例(anterior approach,AA组),对两组患者的骨折愈合时间、胫骨平台后倾角及内翻角、Rasmussen复位解剖学评分、HSS膝关节功能评分进行统计学分析,以期了解不同径路术式与骨折愈合、复位效果、复位稳定性及膝关节功能的相互关系。结果PMA组骨折愈合时间少于AA组。PMA组、AA组的术后即刻与术后12个月胫骨平台后倾角、内翻角比较,均无统计学差异(P>0.05)。术后即刻Rasmussen复位解剖学评分、术后12个月HSS膝关节功能评分两组无统计学差异(P>0.05)。结论胫骨平台后柱骨折前后联合入路手术可以缩短骨折愈合时间,而骨折复位效果、复位的稳定性及膝关节功能恢复两组术式并无差别,应依据胫骨平台后侧骨折块的大小、位置以及骨折断端的走向、移位选择手术径路。     

联合入路手术治疗胫骨平台骨折

目的探讨后内侧倒L形切口联合前外侧入路手术治疗胫骨平台骨折的临床疗效。方法采用后内侧倒L形切口联合前外侧入路手术治疗30例胫骨平台骨折患者。术后对膝关节功能HSS评分和胫骨平台内翻角、后倾角进行评价分析。结果 30例均获得随访,时间12～15个月。骨折均愈合,时间13～22周。术后1例出现切口感染,经清创换药后痊愈。患者术后12个月胫骨平台内翻角及后倾角均恢复良好,膝关节HSS评分为74～96分,优良率为93. 3%。结论联合入路手术治疗胫骨平台骨折可以精确复位和足量植骨以及坚强内固定,有利于膝关节早期功能锻炼,并发症少,临床疗效满意。     

内侧加前外侧入路治疗胫骨平台三柱骨折

目的:探讨运用胫骨平台三柱分型,联合内侧加前外侧入路钢板内固定方法治疗复杂胫骨平台骨折的疗效。方法:2010年3月至2012年3月,采用内侧加前外侧入路,应用"T"形、"L"形钢板或桡骨远端"T"形钢板内固定治疗涉及胫骨平台三柱骨折,共20例。其中男13例,女7例;年龄29~52岁,平均39.4岁;受伤至手术时间8~12 d,平均9 d。末次随访按照美国特种外科医院膝关节功能评分方法评定疗效及测量胫骨平台的内翻角、后倾角、股胫角。结果:患者平均手术时间2.11 h,术中出血量平均452 ml,平均住院时间22.3 d,20例术后均获随访,时间12~20个月,平均14.6个月。骨折愈合时间3~8个月,平均6.1个月。20例胫骨平台内翻角、后倾角、股胫角术后3 d分别为(86.1±2.7)°、(10.7±1.6)°、(168.0±4.7)°,术后1年分别为(84.1±3.2)°、(13.7±1.9)°、(170.0±5.8)°,差异无统计学意义(P>0.05)。末次随访按照美国特种外科医院膝关节功能评分方法评定疗效:优11例,良6例,中2例,差1例。术后无神经及血管损伤,术后1例出现局部感染,1例发生切口皮缘部分坏死,均经保守治疗痊愈。4例术后出现小腿内下方感觉麻木,无螺钉松动、断裂及内固定失效等其他并发症发生。结论:采用内侧加前外侧入路治疗胫骨平台三柱骨折能够术中不更换体位,术后获得更优良的解剖复位和更坚强的固定,有利于膝关节早期功能的锻炼。     

联合入路双钢板固定治疗陈旧性Schatzker Ⅳ型胫骨平台骨折

目的:探讨膝前正中联合内后纵行入路双锁定钢板固定治疗陈旧性SchatzkerⅣ型胫骨平台骨折的临床疗效。方法:自2013年7月至2015年7月,采用膝前正中联合内后侧纵行手术入路、重建锁定钢板固定后内侧骨块及解剖锁定钢板固定内前侧骨块治疗15例陈旧性胫骨平台骨折患者,男9例,女6例;年龄21~61岁,平均49.2岁;左侧8例,右侧7例。均为SchatzkerⅣ型。受伤至手术时间21~65 d,平均26.5 d。术前主要症状体征为膝关节肿胀、疼痛、畸形及活动受限,X线及CT检查确定骨折类型。通过X线片比较术后即刻及末次随访胫骨平台内翻角、股胫角及后倾角等形态学变化,采用美国特种外科医院(Hospital for Special Surgery,HSS)膝关节评分评价临床疗效。结果:术后2例发生切口并发症,经处理愈合;1例继发创伤性关节炎。15例患者均获随访,时间13~24个月,平均16.6个月。无感染、下肢深静脉血栓、内固定松动断裂、骨折再移位及关节面塌陷等并发症发生。骨折愈合时间3~8个月,平均6.07个月。胫骨平台内翻角、股胫角及后倾角,术后即刻分别为(86.81±1.67)°、(168.00±3.29)°及(10.20±1.47)°,末次随访分别为(86.47±1.67)°、(168.53±3.03)°及(10.54±1.21)°,差异无统计学意义(P0.05);HSS膝关节评分:疼痛26.33±3.86,功能20.00±1.79,活动度16.00±1.55,肌力8.67±0.94,屈曲畸形8.53±1.67,稳定性9.33±0.94,总分88.86±8.92;优10例,良4例,中1例。结论:膝前正中联合后内侧入路、双锁定钢板固定治疗陈旧性SchatzkerⅣ型胫骨平台骨折,具有显露充分、复位固定可靠及便于膝关节早期功能锻炼等优点,术后近期疗效满意。     

联合入路双钢板内固定治疗骨折脱位型胫骨内侧平台骨折

目的 :探讨膝前正中入路联合后内侧倒"L"形入路双接骨板内固定治疗骨折脱位型胫骨内侧平台骨折的临床疗效。方法:自2010年2月至2013年9月收治17例骨折脱位型胫骨内侧平台骨折患者,男11例,女6例;年龄21~65岁,平均42岁。采用前正中入路复位固定内侧平台骨折块,后内侧倒"L"形入路复位及支撑固定后内侧骨块,术后进行临床和影像学随访,采用HSS评分进行评价。结果:所有患者获随访,时间11~25个月,平均18个月。术后即刻和随访终末胫骨平台内翻角(TPA)分别为(87.8±4.2)°和(88.2±4.6)°,差异无统计学意义(P=0.458);术后即刻和随访终末胫骨内侧平台后倾角(PSA)分别为(10.1±3.7)°和(10.3±4.1)°,差异无统计学意义(P=0.512)。膝关节HSS评分86.7±6.1,所有患者无感染、皮肤坏死、内固定松动断裂及骨折复位丢失等并发症。结论:联合入路双钢板固定治疗骨折脱位型胫骨内侧平台骨折,具有显露清楚、复位满意、固定可靠、便于早期功能锻炼等优点,临床效果满意。     

波及后髁的胫骨平台骨折手术入路选择

目的以胫骨平台三柱分型理论为指导,设计波及后髁胫骨平台骨折的手术入路并观察术后疗效。方法自2011-01—2013-09以三柱分型理论为指导对17例波及后髁的胫骨平台骨折设计相应的手术入路进行内固定,单纯后柱骨折以及后柱骨折+内侧柱骨折设计膝关节后方倒L形入路,外侧柱+后柱骨折以及外侧柱+内侧柱+后柱骨折设计膝关节后方倒L形入路+前外侧入路。术后定期摄膝关节X线片观察骨折愈合情况并测量胫骨平台的内翻角及后倾角,以膝关节Rasmussen功能评分对术后疗效进行评估。结果17例术后均获平均13.7(12~17)个月随访。骨折临床愈合时间为3~8个月,平均5.6个月。术后即刻胫骨平台内翻角为(86.27±0.35)°,术后1年为(86.39±0.32)°,差异无统计学意义(t=-0.911,P=0.376);术后即刻胫骨平台后倾角为(9.15±0.34)°,术后1年胫骨平台后倾角为(9.17±0.34)°,差异无统计学意义(t=0.557,P=0.585)。术后1年膝关节功能Rasmussen评分:优9例,良7例,可1例,优良率94.1%。结论胫骨平台三柱分型理论对设计波及后髁的胫骨平台骨折手术入路有指导意义,但该理论在设计胫骨平台后髁合并外侧髁骨折手术入路时可能需要进一步明确骨折亚型。     

改良后侧倒“L”形入路治疗累及胫骨平台后柱内外侧骨折

目的 观察改良后侧倒“L”形入路治疗累及后柱内外侧胫骨平台骨折的手术方法及临床疗效。方法 对7例累及后柱内外侧胫骨平台骨折采用改良后侧倒“L”形入路切开复位内固定术进行治疗。比较术后即刻、12个月的胫骨平台内翻角(tibial plateau angle,TPA)、胫骨平台后倾角(posterior tibial angle,PA),采用HSS膝关节评分及膝关节活动度(range of motion,ROM)评价术后疗效。结果 本组均获12~20个月随访,骨折全部愈合,术后12个月HSS膝关节评分71~93分,平均(81.4±7.2)分,ROM平均为(120.1±1.3)°。术后即刻与12个月TPA、PA度数比较差异均无统计学意义(P0.05)。结论 改良后侧倒“L”形入路可治疗复杂的累及后柱内外侧胫骨平台骨折,尤其适用于后柱外侧骨折需要单独用支撑钢板固定者。     

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.