全凭静脉麻醉与静吸复合麻醉恢复质量及用药相关费用的比较

目的 比较相同麻醉深度下异氟醚-芬太尼静吸复合麻醉与丙泊酚复合芬太尼或雷米芬太尼全凭静脉麻醉的恢复质量和用药相关费用.方法 ASA Ⅰ或Ⅱ级,择期行下腹部手术患者60例,随机均分为静吸复合组(B组)、芬太尼组(F组)及雷米芬太尼组(R组),分别以异氟醚-芬太尼、丙泊酚-芬太尼和丙泊酚-雷米芬太尼辅以维库溴铵维持麻醉.麻醉深度维持在Narcotrend D0～D2水平,记录术毕停药后患者自主呼吸恢复时间、呼名睁眼时间、拔管时间、定向力恢复时间;观察拔管后即刻、拔管后20 min患者意识状态(OAA/S)、疼痛程度(VAS)及主诉需要镇痛药的例次;术后24 h访视患者,记录有无术中知晓及恶心、呕吐等不良反应;比较三种麻醉方式的用药相关费用.结果 三种麻醉方式术毕自主呼吸恢复时间、呼名睁眼时间、拔管时间的差异无统计学意义,但R组定向力恢复早于B组,其拔管后20 min患者OAA/S评分也高于B组(P＜0.01).R组在拔管后即刻及拔管后20 min VAS明显高于其他两组,主诉需要镇痛药者也多于其他两组(P＜0.01).三组患者术后恶心、呕吐等不良反应发生率的差异无统计学意义.B组麻醉用药相关费用明显低于其他两组(P＜0.01).结论 三种麻醉方式麻醉苏醒速度相近,丙泊酚-雷米芬太尼苏醒质量较好,但麻醉恢复期疼痛明显.全凭静脉麻醉特别是丙泊酚-雷米芬太尼用药相关费用高于异氟醚-芬太尼静吸复合麻醉.     

脑电双频指数在全凭静脉麻醉中的作用

目的 评价脑电双频指数(BIS)监测对全凭静脉麻醉用药及苏醒质量的影响.方法 鼻内窥镜手术全凭静脉麻醉患者66例随机均分为BIS组(Ⅰ组)和常规组(Ⅱ组),均采用丙泊酚联合雷米芬太尼双通道靶控输注.记录术中麻醉药用量、睁眼时间、拔管时间、语言指令反应恢复时间、定向力恢复时间及术中知晓发生率.结果 Ⅰ组丙泊酚用量显著少于Ⅱ组(P<0.05),而且其睁眼时间、拔管时间、语言指令反应恢复时间、定向力恢复时间均明显短于Ⅱ组(P<0.05).两组均无术中知晓发生.结论 BIS监测可减少全凭静脉麻醉丙泊酚用量并改善麻醉苏醒质量.     

七氟醚复合雷米芬太尼快通道麻醉在鼻内窥镜手术中的应用

目的观察七氟醚复合雷米芬太尼快通道麻醉在鼻内窥镜手术中的应用效果。方法 60例择期行鼻内窥镜手术患者,年龄21～55岁,随机分为三组,每组20例。Ⅰ组全凭吸入七氟醚麻醉,Ⅱ组丙泊酚复合雷米芬太尼,Ⅲ组七氟醚复合雷米芬太尼。观察三组患者术中、术后血流动力学变化,记录术后拔管时间、清醒时间、术后躁动评分(RS)、意识状态评分(OAA/S)等。结果三组术中血压控制均较满意。术后Ⅱ、Ⅲ组拔管时间及清醒时间较Ⅰ组短,躁动发生率稍低(P0.05)。结论七氟醚复合雷米芬太尼静吸复合麻醉与丙泊酚复合雷米芬太尼全凭静脉麻醉均为鼻内窥镜手术提供安全、快捷、苏醒彻底的快通道麻醉方法。     

雷米芬太尼用于胆囊腹腔镜手术麻醉

目的评价雷米芬太尼靶控输注（TCI）全凭静脉麻醉（TIVA）的诱导和术后苏醒过程。方法ASAⅠ～Ⅱ级择期行胆囊腹腔镜切除手术病人40例,随机分为芬太尼（F组）和雷米芬太尼（RF组）两组,每组20例。观察麻醉诱导气管插管及拔管期的SBP、DBP、HR、术中血液动力学变化;术毕停药后病人自主呼吸恢复时间、呼之睁眼时间、拔管时间、离开恢复室时间及疼痛状况、恶心呕吐等不良反应。结果在插管后即刻、插管后5minRF组SBP、DBP、HR的变化均明显小于F组（JP〈0．01）;在切皮、麻醉维持期间两组病人血液动力学变化基本相似。两组病人从手术结束到呼之睁眼和拔除气管导管的时间及血管活性药物的用量基本相似。RF组术后疼痛的例数明显多于F组（P〈0．05）。结论依托咪酯和雷米芬太尼TCI TIVA的诱导更加平稳,苏醒质量高。但由于雷米芬太尼消除半衰期短,术后镇痛应及时建立。     

雷米芬太尼对肝硬化后脾切除术患者苏醒的影响

目的观察雷米芬太尼在肝硬化患者脾切除手术的应用中对其麻醉苏醒的影响。方法选择肝炎后肝硬化合并脾功能亢进患者40例,随机均分为雷米芬太尼组(Ⅰ组)和芬太尼组(Ⅱ组)。分别以雷米芬太尼和芬太尼作为麻醉镇痛药,观察两组手术结束停药后患者呼之睁眼时间、自主呼吸恢复时间、拔管时间、定向力恢复时间,观察患者拔管后即刻、拔管后30min和1h的意识状态(OAA/S评分)。结果Ⅰ组患者的呼之睁眼时间、自主呼吸恢复时间、拔管时间、定向力恢复时间均短于Ⅱ组(P<0.05)。结论雷米芬太尼用于肝功能不全的患者安全、有效,而且代谢快,有利于术后恢复,是一种更理想的麻醉镇痛药。     

小儿丙泊酚、雷米芬太尼全凭静脉麻醉与丙泊酚、芬太尼和氧化亚氮复合麻醉的比较

目的比较丙泊酚、雷米芬太尼全凭静脉麻醉与丙泊酚、芬太尼和氧化亚氮(N2O)复合麻醉用于小儿外耳再造手术的临床效果。方法40例5~12岁的患儿随机分为丙泊酚、雷米芬太尼组(P-R组)与丙泊酚、芬太尼和N2O组(P-F-N2O组)。麻醉诱导后,P-R组持续输注丙泊酚和雷米芬太尼;P-F-N2O组持续输注丙泊酚、芬太尼和维库溴铵,辅助吸入60%N2O维持麻醉。术中根据循环反应和体动情况调整丙泊酚和芬太尼的输注速度。记录术中循环变化,术后麻醉恢复情况和疼痛情况。结果与P-F-N2O组相比,P-R组术中MAP下降明显,丙泊酚平均用量降低(P<0.01),睁眼时间、对语言命令反应时间和定向力恢复时间缩短(P<0.01),术后4 h内视觉模拟评分(VAS)增加(P<0.01)。结论与P-F-N2O组相比,P-R组丙泊酚用量明显减少,术后清醒迅速、平稳,但术后早期疼痛较为明显。     

雷米芬太尼和芬太尼用于老年患者全凭静脉麻醉的临床比较

目的比较雷米芬太尼及芬太尼用于老年患者全凭静脉麻醉(TIVA)诱导、维持及苏醒的效果。方法40例择期行胆囊手术及胃部手术的患者,随机均分为雷米芬太尼组(RF组)及芬太尼组(F组),分别以雷米芬太尼和芬太尼为TIVA的麻醉性镇痛药,观察两组诱导前(T0)、插管前即刻(T1)、插管后1min(T2)、5min(T3)、切皮后5min(T4)、30min(T5)的BP及HR的变化以及苏醒时的咽喉反射恢复时间、睁眼时间和拔管时间。结果与T0时相比,T1、T2和T4时RF组的SBP、DBP下降均比F组显著(P<0.05或P<0.01);在麻醉恢复期,RF组患者咽喉反射恢复时间、睁眼时间和拔管时间均显著短于F组(P<0.01)。结论与芬太尼相比,雷米芬太尼是更理想的全麻镇痛药。     

雷米芬太尼复合丙泊酚与复合地氟醚麻醉在脊柱侧弯矫正术中唤醒的比较

目的比较脊柱侧弯矫正术中,丙泊酚复合雷米芬太尼靶控静脉麻醉和地氟醚复合雷米芬太尼静吸复合麻醉的术中唤醒时间及苏醒质量。方法40例择期行脊柱侧弯矫正术患者,ASAⅠ或Ⅱ级,随机均分为丙泊酚复合雷米芬太尼靶控静脉麻醉组(P组)和地氟醚复合雷米芬太尼静吸复合组(D组)。比较停止输注丙泊酚或地氟醚后术中唤醒时间及唤醒质量。结果D组患者自主呼吸恢复时间(5.2±1.8)min,呼之睁眼时间(5.2±1.8)min和指令动作恢复时间(7.1±1.2)min均短于P组[(7.2±1.3)min,(8.3±1.7)min和(9.5±1.0)min](P<0.05)。唤醒成功时,P组患者有4例睁眼勉强,并伴有四肢不自主活动,苏醒质量为2级;D组均为1级。结论术中维持相同的循环指标,D组唤醒时间要短于P组,D组唤醒质量也优于P组。     

雷米芬太尼、芬太尼、氯胺酮复合丙泊酚用于小儿烧伤和整形手术的比较

目的比较雷米芬太尼、芬太尼和氯胺酮复合丙泊酚保留自主呼吸全麻用于小儿烧伤和整形手术,观察麻醉中血液动力学的变化和术后恢复时间以及不良反应。方法选择51例ASAⅠ～Ⅱ级择期烧伤或整形的患儿,随机均分为三组,丙泊酚与雷米芬太尼组(R组);丙泊酚与芬太尼组(F组);丙泊酚与氯胺酮组(K组)。观察并记录患儿给药前、给药后5min、切痂、植皮以及停药后5min时的MAP、HR、RR、SpO2、PETCO2和术后恢复时间以及不良反应。结果R组MAP和HR在给药后有所下降但术中基本保持平稳,而F组MAP和HR术中波动明显(P<0.05,P<0.01),K组术中MAP较高、HR较快(P<0.05,P<0.01)。R组术后恢复时间明显短于F组和K组(P<0.01),而F组又明显短于K组(P<0.05,P<0.01)。R组呼吸抑制发生率高于F组和K组。结论雷米芬太尼与丙泊酚复合较芬太尼与丙泊酚复合和氯胺酮与丙泊酚复合对术中血液动力学影响更小,术后苏醒时间更快,但应注意诱导时呼吸抑制的发生。     

异丙酚复合芬太尼或瑞芬太尼靶控静脉麻醉与静吸复合麻醉的比较

目的 评价异丙酚和瑞芬太尼靶控静脉麻醉的诱导和术后苏醒过程。方法 ASA Ⅰ-Ⅱ级择期行腹腔镜胆囊切除手术的病人60例,年龄<65岁,随机分为静吸复合麻醉(C)组、异丙酚瑞芬太尼靶控(R)组及异丙酚芬太尼靶控(F)组,每组20例。观察麻醉诱导及气管插管时的血压、心率;记录术毕停药后病人自主呼吸恢复时间、呼之睁眼时间、拔管时间、定向力恢复时间和离开恢复室时间;观察病人拔管后即刻、离开恢复室、拔管后1、3和24h的意识状态(OAAS),认知功能测试(MMSE),疼痛评分(VRS)及主诉需要阿片药镇痛的时间;观察恶心呕吐等副反应,记录术中知晓的发生率和病人满意度等。结果 ①C组诱导时的舒张压低于R组和F组,低血压者多于R组,插管反应发生率高于R组。F组的插管反应发生率高于R组。②三组病人术后自主呼吸恢复时间、呼之睁眼时间、拔管时间差异无显著性,但F组的定向力恢复时间和离开术后恢复室(PACU)的时间早于C组。F组病人在拔管后即刻、离开PACU时、拔管后1h和3h的OAAS评分高于C组,R组病人离开PACU时的OAAS评分高于C组。F组病人拔管后1h的MMSE评分高于C组。R组病人在拔管后即刻、离开PACU时、拔管后1h和术后24h的VBS评分高于C组和F组,需要阿片药镇痛者R组多于其他两组。三组病人术后的恶心呕吐发生率差异无显著性。结     

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.