尼卡地平控制性降压对家犬脊髓诱发电位的影响

目的观察尼卡地平控制性降压对家犬脊髓诱发电位（SCEPs）的影响，探讨脊柱手术麻醉中尼卡地平控制性降压的安全性。方法成年杂种犬6只，体重12．0～15．5kg，用2．5o,4硫喷妥钠行麻醉诱导并维持麻醉。股动脉置管监测MAP。以尼卡地平8μg·kg^-1·min^-1持续静脉注射进行控制性降压，降压标准为基础MAP的40％。以日本光电诱发电位监测仪测定SCEPs。结果MAP平均下降幅度为42．9％，控制性降压后体感诱发电位（SEP）波幅及运动诱发电位（MEP）波幅差异无统计学意义。结论尼卡地平控制性降压对SCEPs影响较小，可安全用于脊髓手术。     

常压及控制性降压下脊髓急性牵拉损伤比较研究

目的 评价控制性降压是否增加脊髓对牵拉损伤的易感性。材料与方法健康成年杂种犬6只，随机分为常压和控制性降压脊髓牵拉损伤组。观察常压及控制性降压水平下相同程度牵拉损伤后脊髓血流(SCBF)、体感诱发电位(SEP)、神经源性运动诱发电位(NMEP)改变的差异。结果 外周血有创动脉压(MABP)平均下降幅度为40．5％。经SSPS统计软件独立样本t检验，不同牵拉水平下，常压组及低压组的SCBF(％)、SEP波幅(Asep)(％)及NMEP波幅(％)无显著差异。结论 尼卡地平控制性降压不增加脊髓对牵拉损伤的易感性。     

尼卡地平控制性降压对腹腔镜下行直肠癌根治术老年患者术后认知功能的影响

为探讨尼卡地平控制性降压对腹腔镜下行直肠癌根治术的老年患者术后认知功能的影响,将择期腹腔镜下行直肠癌根治术的老年患者80例,随机分为控制性降压组和对照组各40例。控制性降压组于手术开始后静脉输注尼卡地平0．5～6μg／（kg·min）行控制性降压,维持平均动脉压（MAP）较麻醉前降低30％左右（不低于60mmHg）。对照组不行控制性降压。两组于麻醉诱导前（基础状态）及术后24h、48h应用简易智能状态检查法（MMSE）评估认知功能。结果显示,控制性降压组术中MAP较对照组明显降低（P〈0．05）;与基础值比较,术后24h、48h两组MMSE评分差异无统计学意义（P〉0．05）;两组患者均未发生术后认知功能障碍。结果表明,尼卡地平0．5～6μg／（kg·min）行控制性降压,对腹腔镜下行直肠癌根治术老年患者术后认知功能无明显影响。     

髋部手术全麻患者硝普钠或尼卡地平控制性降压的安全性

目的评价髋部手术全麻患者硝普钠或尼卡地平控制性降压的安全性。方法择期行髋部手术全麻患者20例,随机分为Ⅰ组(硝普钠组,n=10)和Ⅱ组(尼卡地平组,n=10)。在静吸复合全身麻醉下,分别于手术开始时静脉输注硝普钠(0．5-8 μg·kg-1·min-1)或尼卡地平(1-8μg·kg-1· min-1),使平均动脉压降至55-65 mm Hg,并维持此水平至术毕。用食管超声多普勒血流监测仪监测血液动力学变化,记录降压前即刻(基础值)、降压15 min、30 min、60 min及停降压药后15 min、30 min时主动脉血流量(ABF)、心输出量(CO)、主动脉每搏流量(SVa)、左室射血时间(LVETi)、左室射血峰速度 (PV)、血流加速度(Acc)、主动脉内全身血管阻力(TSVRa);记录术中出血量、输液量、尿量、术后伤口引流量及需异体输血情况;于术前和术后24 h抽取静脉血,测定肝肾功能。结果与基础值比较,两组降压过程中及停降压药后MAP及TSVRa降低,降压过程中HR增快,Ⅰ组降压过程中CVP降低, ABF、CO升高,LVETi延长(P<0．05)。与Ⅱ组比较,Ⅰ组停降压药后30 min时MAP升高,LVETi延长, 降压时间及升压时间缩短,术中出血量和异体输血率降低(P<0．05或O．01)。两种药物对肝、肾功能无明显影响。结论硝普钠及尼卡地平均可安全地用于全身麻醉患者控制性降压,但硝普钠降压的可控性优于尼卡地平,且能更有效地减少术中出血。     

尼卡地平控制性降压对颅内压的影响

目的 观察尼卡地平控制性降压对颅内压(ICP)的影响.方法 选择ASA Ⅰ或Ⅱ级神经外科手术患者20例,年龄19～50岁.行腰椎穿刺术直接测得ICP.尼卡地平起始剂量为0.01%～0.02%的溶液静脉滴注,维持SBP在100 mm Hg以下.记录降压前(T0)、降压10 min(T1)、20min(T2)、30 min(T3)和结束降压后10 min(T4)、20 min(T5)的ICP、rSO2、HR、MAP.结果 T1～T3时MAP显著低于T0(P<0.01).T4时MAP明显回升(P<0.05),T5时回到T0水平.降压期间ICP、rSO2、HR无明显改变.结论 尼卡地平降压起效快,降压平稳,对ICP、脑氧饱和度无明显影响.     

尼卡地平控制性降压对局部脑氧饱和度的影响

目的观察颅内动脉瘤夹闭术中控制性降压对局部脑氧饱和度(rScO2)的影响。方法 15例ASAⅠ级的择期颅内动脉瘤夹闭手术患者,丙泊酚-瑞芬太尼全凭静脉麻醉,暴露动脉瘤期间静脉泵注尼卡地平0.5～1μg·kg-1·min-1,逐渐降低术前基础MAP的10%、20%和30%,夹闭动脉瘤后停止降压,观察降压过程中MAP、HR和rScO2的变化趋势。结果尼卡地平控制性降压过程中,随着MAP的逐渐下降,rScO2略有升高,T5时rScO2恢复至T1水平,各时点MAP、HR、PETCO2、BIS和rScO2差异均无统计学意义。结论颅内动脉瘤夹闭术中应用尼卡地平行控制性降压安全可行,不会影响脑氧供需平衡。     

尼卡地平控制性降压联合中度高容量血液稀释对内脏氧合及全身炎性反应的影响

目的研究尼卡地平控制性降压联合中度急性高容量血液稀释(AHH)对内脏氧合及全身炎性反应的影响。方法神经外科病人10例,麻醉诱导后30min内行中度AHH,使红细胞压积(Hct)降至30%,术中采用尼卡地平控制性降压,并维持MAP在55~65mmHg。观察入室(T0)、血液稀释至目标值(T1)、控制性降压至目标值(T2)、降压达目标值后30min(T3)、降压停止(T4)和术毕(T5)时胃粘膜二氧化碳分压(PgCO2)、PgCO2与动脉血二氧化碳分压差(Pg-aCO2)、胃粘膜pH值(i-pH),测定T1、T3和T5时血清肿瘤坏死因子α(TNF-α)、白细胞介素-8(IL-8)和β2-微球蛋白(β2-MG)含量。结果T1、T2、T5时的i-pH与T0时相比显著降低(P<0·05),T1、T2、T3时的Pg-aCO2与T0时相比明显升高(P<0·05)。T4、T5时的血乳酸(Lac)水平明显高于T0时(P<0·05)。各时点的TNF-α含量较正常值明显增加(P<0·05),而IL-8和β2-MG含量无显著改变。结论中度AHH可能会导致内脏氧合受损,并激发全身炎性反应,联合尼卡地平控制性降压可部分缓解内脏氧合受损和全身炎性反应。     

尼卡地平与低剂量艾司洛尔联合控制性降压对血液儿茶酚胺、β2-微球蛋白和血乳酸的影响

目的研究尼卡地平与低剂量艾司洛尔联合控制性降压方法的可行性及对血液儿茶酚胺、＆2-微球蛋白(β2-mG)和组织氧代谢的影响.方法择30例择期手术的骨肿瘤病人,随机分为三组对照组(C组,n=10),不实施控制性降压,仅泵入生理盐水;尼卡地平组(N组,n=10),尼卡地平、艾司洛尔联合15组(N+E组,n=10),N组和N+E组尼卡地平起始药物速率为2.5μg@kg-1@min-1,艾司洛尔速率12.5μg@kg-1@min-1(NE=15).降至目标血压后(MAP 60～70mm Hg),调整药物剂量使MAP维持在此范围.分别于降压前、降至目标血压时、降至目标血压后30min、降压停止时以及术毕,采集动脉血分别测定血液儿茶酚胺水平、血清β2-mG含量、血乳酸含量和血红蛋白,同时记录各时间点的HR、MAP、CVP和降压期间的尿量.结果 C组与N组降压期间血去甲肾上腺素(NE)水平明显增加且呈递增趋势(P＜0.05),N+E组病人NE水平虽有升高但保持在低水平(P＞0.05);而其它两组病人则无明显改变.三组病人降压期间β2-mG含量均无明显升高,但降压期间的血乳酸含量升高显著(P＜0.05).结论尼卡地平控制性降压不会造成组织无氧代谢发生及潜在肾损害,其与低剂量艾司洛尔联合(15)可作为一种控制性降压方法,且具有部分抗应激作用,有助于降压期间内脏血流的维护.     

尼卡地平控制性降压下脑膜瘤切除术患者内脏灌注的变化

目的 观察尼卡地平控制性降压下脑膜瘤切除术患者内脏灌注的变化。方法 择期行脑膜瘤切除术的患者23例,ASAⅡ-Ⅳ级,全麻诱导插管后打开脑膜至肿瘤切除期间静脉注射尼卡地平行控制性降压,使MAP≥60 mm Hg。在降压前(T0)、降压1 h(T1)、降压2 h(T2)、降压3 h(T3)、停降压后1 h(T4)、停降压后2 h(T2)分别记录血液动力学指标、胃粘膜内二氧化碳分压(pgCO2),同时点测定动脉血pH值及动脉血二氧化碳分压,根据Henderson-Hasselbalch公式,计算出胃粘膜pH(pHi)及PgCO2-PaCO2差值(PCO2gap)。结果 降压期间MAP≥60mm Hg,停降压后恢复至基础值。与T0比较,MAP、红细胞压积在T1、T2、T3显著性下降(P<0.05),其余各项指标在各时间点差异均无显著性。PgCO2、pHi、PCO2gap在各时间点与T0比较差异均无显著性(P>0.05)。结论 在维持氧输送的情况下,尼卡地平短时间控制性降压不影响内脏灌注。MAP≥60mm Hg作为控制性降压的阈值是合理的。     

尼卡地平或乌拉地尔在冠状动脉旁路移植术转流中控制血压效果的研究

目的　比较尼卡地平或乌拉地尔在体外循环中控制血压的效果及其对血液动力学的影响。方法　 60例冠状动脉旁路移植术 ( CABG)病人在体外循环 ( CPB)中平均动脉压 ( MAP)升至80 mm Hg( 1k Pa=7.5 mm Hg)时接受尼卡地平或乌拉地尔治疗。60例病人随机分为尼卡地平组或乌拉地尔组 ,每组 3 0例 ;另设同时期同类病人 3 0例作为对照组。观察两药起效时间 ,维持 MAP在 ( 70±5 ) mm Hg所需剂量 ,降压期间对人工肺血面的影响 ,停机后的血液动力学及混合静脉血氧饱和度( SvO2 )变化。结果　将 MAP从 80 m m Hg降至 70 m m Hg,应用尼卡地平 4μg· kg- 1 · min- 1 所需时间为 ( 2 .4± 1.1)分 ,维持 MAP在 ( 70± 5 ) m m Hg所需剂量为 ( 1.1± 0 .5 ) μg·kg- 1· m in- 1。应用乌拉地尔 90 μg· kg- 1· min- 1所需时间为 ( 2 .8± 1.0 )分 ,维持 MAP在 ( 70± 5 ) mm Hg所需剂量为 ( 5 0 .8±14 .4 ) μg· kg- 1· min- 1 ,但有 2例耐药 ,需不断增加剂量方能控制血压。尼卡地平组 19例 ( 63 % ) ,乌拉地尔组 2 2例 ( 73 % )心脏自动复跳 ,两组的自动复跳率均高于对照组 ( 4 6.2 % ) ( P<0 .0 5 ) ,但两组之间无差异 ( P>0 .0 5 )。停机后两组外周阻力 ( SVR)较 CPB前均明显下降 ( P<0 .0 1) ,每搏量 ( SV)     

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.