中低位直肠癌环周切缘状态与预后的关系研究

目的 探讨中低位直肠癌环周切缘状态与预后的关系,并分析与临床病理特征的关系.方法 采用大组织切片技术,对49例行全直肠系膜切除术的中低位直肠癌标本环周切缘状态进行检查.采用Kaplan-Meier法分析术后局部复发率、远处转移率和5年生存率与环周切缘的关系,并对临床病理特征进行单因素分析. 结果 中低位直肠癌环周切缘阳性率为24%(12/49),术后局部复发率为12%(6/49),远处转移率为27%(13/49).环周切缘阳性的中低位直肠癌局部复发率为33%(4/12),明显高于环周切缘阴性的5%(2/37)(X2=6.577,P=0.010);环周切缘阳性的远处转移率为50%(6/12),切缘阴性者为19%(7/37)(X2=4.491,P=0.034);环周切缘阳性的5年生存率为33%,明显低于环周切缘阴性的78%,Kaplan-Meier生存分析显示,环周切缘与生存时间密切相关(log-rank,P=0.009).环周切缘状态与肿瘤直径(X2=4.451,P=0.035)、T分期(X2=20.283,P=0.000)、N分期(X2=7.773,P=0.018)、肿瘤距齿状线距离(X2=6.502,P=0.04)、肿瘤位置(X2=4.421,P=0.035)及手术方式(X2=5.754,P=0.016)有关.结论 环周切缘状态是影响中低位直肠癌预后的重要因素,中低位直肠癌环周切缘状态与肿瘤直径、T分期、N分期、肿瘤距齿状线距离、肿瘤位置及手术方式存在相关.     

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目的探讨中下段直肠癌根治性切除术后局部复发的危险因素。方法回顾性分析2001年12月至2003年7月广东省人民医院收治的行直肠系膜全切除的中下段直肠癌56例临床资料,采用病理大切片技术检测直肠系膜转移及环周切缘情况,分析其与局部复发的相关性,同时分析局部复发与临床病理特征的关系。结果中下段直肠癌根治性切除术后局部复发率为12.5%(7/56)。局部复发与肿瘤家族史(P=0.047)、血CEA水平(P=0.026)、癌性穿孔(P=0.004)、肿瘤分化程度(P=0.009)及脉管侵袭(P=0.001)密切相关。中下段直肠癌直肠系膜环周切缘阳性率为21.4%(12/56);环周切缘阳性的中下段直肠癌局部复发率为33.3%(4/12),明显高于环周切缘阴性的6.8%(3/44),两组差异有统计学意义(P=0.014)。中下段直肠癌直肠系膜转移率为64.3%(36/56);系膜转移阳性的中下段直肠癌局部复发率为16.7%(6/36),高于系膜转移阴性的5.0%(1/20),但两组差异无统计学意义(P=0.206)。结论肿瘤家族史、血CEA水平、癌性穿孔、肿瘤分化程度、脉管侵袭和环周切缘是中下段直肠癌根治性切除术后局部复发的重要因素。     

中下段直肠癌直肠系膜转移的研究

目的探讨中下段直肠癌系膜转移与临床病理特征的关系。方法对56例行直肠系膜全切除的中下段直肠癌采用病理大切片法检测直肠系膜转移情况,并分析其与临床病理特征的关系。结果中下段直肠癌直肠系膜转移率为64．3％（36／56）。直肠系膜淋巴结转移率为51．8％（29／56）;直肠系膜癌巢阳性率44．6％（25／56）。直肠系膜转移病灶距肿瘤远端最远有5cm。肿瘤直径35cm中下段直肠癌系膜转移率为83．3％（15／18）,而肿瘤直径＜5cm仅为55．3％（21／38）（P=0．041）。T1、T2和T3期直肠癌直肠系膜转移率分别为1／6、56．6％（13／23）和81．5％（22／27）（P=0．007）。高分化、中分化和低分化直肠癌直肠系膜转移率分别为1／5、63．2％（23／37）和85．7％（12／14）（P=0．028）。I期、Ⅱ期和Ⅲ期直肠癌直肠系膜转移率分别为1／5、27．3％（6／22）和100％（29／29）（P=0．000）。直肠系膜转移率与性别、年龄、肿瘤侵袭肠壁周径、Ming分型无关（P＞0．05）。结论中下段直肠癌直肠系膜转移与肿瘤直径、浸润深度、分化程度和分期密切相关。中下段直肠癌应行直肠系膜全切除或远端直肠系膜切除至少5cm。     

中下段直肠癌E-cadherin，MMP-2和VEGF表达与肿瘤侵袭转移的关系

为探讨中下段直肠癌肿瘤组织E-cadherin,MMP-2和VEGF的表达及其与肿瘤侵袭转移的关系。笔者采用免疫组化技术检测56例中下段直肠癌肿瘤组织中E-cadherin,MMP-2和VEGF的表达。结果示，44.6%（25/56）的中下段直肠癌E-cadherin表达阴性;其中T3的阴性率为63.0%，明显高于T2和T1的26.1%和33.3%（P=0.028）。淋巴结转移阳性的直肠癌E-cadherin表达阴性率为62.1%，明显高于淋巴结转移阴性者的25.9%（P=0.007）。MMP-2表达阳性率为75.0%（42/56）;其中T3，T2阳性率分别为88.9%，69.6%，明显高于T1期的33.3%（P=0.013）。浸润型直肠癌MMP-2表达率为91.2%，明显高于膨胀型的40.0%（P=0.001）。淋巴结转移阳性者MMP-2表达率为86.2%，明显高于淋巴结转移阴性的63.0%（P=0.045）。VEGF表达率为57.1%（32/56）;其中T3 VEGF表达率为74.1%，明显高于T2和T1期的43.5%和33.3%（P=0.043）;淋巴结转移阳性者VEGF表达率为72.4%，明显高于淋巴结转移阴性的40.7%（P=0.017）。提示中下段直肠癌E-cadherin表达阴性和MMP-2，VEGF表达阳性与肿瘤侵袭和转移有密切关系。     

中下段直肠癌基质金属蛋白酶-2表达与直肠系膜转移的关系

目的分析基质金属蛋白酶-2（MMP-2）在中下段直肠癌的表达及与直肠系膜转移的关系。方法采用病理大切片技术前瞻性研究56例中下段直肠癌直肠系膜转移的情况，免疫组织化学技术检测肿瘤组织MMP-2的表达。结果75％（42／56）的中下段直肠癌MMP-2表达阳性；T2、T3期直肠癌MMP-2表达阳性率分别为69．6％和88．9％，明显高于T1期直肠癌的33．3％（P=0．013）。Ming分型中，浸润型直肠癌MMP-2表达阳性率为91．2％，明显高于膨胀型直肠癌的40．0％（P=0．001）。中下段直肠癌直肠系膜转移率为64．3％（36／56）。系膜转移阳性的36例中有31例（86．1％）MMP-2表达阳性，而系膜转移阴性的20例中仅11例（55．0％）MMP-2表达阳性（P=0．01）。结论中下段直肠癌MMP-2表达与浸润深度和Ming分型密切相关。MMP-2可能参与中下段直肠癌直肠系膜转移的发生。     

低位直肠癌直肠系膜淋巴结转移规律的临床探讨

目的探讨低位直肠癌直肠系膜淋巴结转移与临床病理特点的关系。方法对62例行直肠系膜全切除（total mesorectal excision,TME）的低位直肠癌采用大组织切片技术检测直肠系膜淋巴结转移情况,分析其转移规律。结果低位直肠癌系膜转移率为72.6%（45/62）（其中系膜淋巴结阳性29例,系膜癌巢阳性16例）。①不同临床病理类型的系膜转移率为：肿瘤直径≥5 cm者为90.5%（19/21）,明显高于肿瘤直径〈5 cm的63.4%（26/41）（P〈0.05）。②T1、T2和T3期者分别为22.2%（2/9）、68.0%（17/25）和92.9%（26/28）,组内两两比较具有显著性差异（P〈0.05或P〈0.01）。③高、中、低分化者为14.3%（1/7）7、9.5%（31/39）和81.3%（13/16）,高分化者明显低于中、低分化者（P〈0.05）。④Ⅰ、Ⅱ、Ⅲ期者分别为11.1%（1/9）、63.6%（14/22）和96.8%（30/31）,Ⅰ期者明显低于Ⅱ、Ⅲ期者（P〈0.05）。⑤环周切缘阳性者为93.3%（14/15）,明显高于环周切缘阴性者66.0%（31/47）（P〈0.05）。直肠系膜转移率与患者性别、年龄、肿瘤侵袭肠壁周径、Ming分型无关（P〉0.05）。结论低位直肠癌直肠系膜淋巴结转移与肿瘤直径、浸润深度、分化程度和肿瘤分期密切相关;环周切缘阳性者,其直肠系膜淋巴结转移的可能性越高。因此,低位直肠癌应遵循彻底TME原则。     

中下段直肠癌血管内皮生长因子表达与直肠系膜转移的关系

目的分析中下段直肠癌血管内皮生长因子（VEGF）表达与临床病理特征的关系。初步探讨中下段直肠癌直肠系膜转移的分子机制。方法采用病理大切片前瞻性研究56例中下段直肠癌直肠系膜转移情况，采用免疫组织化学技术检测肿瘤组织VEGF表达。结果57．1％（32／56）中下段直肠癌VEGF表达阳性；T3直肠癌VEGF表达阳性率为74．1％。明显高于配和T1直肠癌的43．5％和33．3％（P〈0．05）；淋巴结转移阳性的中下段直肠癌VEGF表达阳性率为72．4％明显高于淋巴结转移阴性的40．7％（P〈0．05）；中下段直肠癌直肠系膜转移率为64．3％（36／56）。36例系膜转移阳性直肠癌25例（69．4％）VEGF表达阳性，而20例系膜转移阴性直肠癌仅7例（35％）VEGF表达阳性，两者差异有统计学意义（P〈0．05）。结论中下段直肠癌VEGF表达与浸润深度和淋巴结转移密切相关。VEGF可能参与中下殷盲肠癌盲肠系膊转移的发生．     

经肛门全直肠系膜切除和腹腔镜全直肠系膜切除对直肠癌的疗效对比

目的分析比较经肛门全直肠系膜切除（TaTME）与腹腔镜全直肠系膜切除（LaTME）在中低位直肠癌治疗中的疗效及预后。 方法选择东营市东营区人民医院2015年2月至2016年2月收治的64例择期行全直肠系膜切除术（TME）的中低位直肠癌患者，随机分为TaTME组与LaTME组，各32例。观察并比较两组患者的手术时间、术中出血量、标本完整率、环周切缘（CRM）阳性率、远端切缘（DRM）阴性率、淋巴结清扫数目、保肛率、中转开放手术率、术中及术后并发症、术后住院时间、局部复发率、远处转移率、2年总体生存率（OS）各指标间的差异。 结果TaTME组患者的术中出血量、中转开放手术率、手术时间、标本完整率、CRM阳性率、保肛率、术后住院时间、尿潴留发生率均显著优于LaTME组（均P<0.05）。患者均获随访2~24个月，TaTME组中位生存时间为23.9个月，局部复发率、转移率分别为6.2%（2/32）、3.1%（1/32）。LaTME组中位生存时间为19.7个月，局部复发率、转移率均为3.1%（1/32）。两组术后复发率、转移率比较，差异无统计学意义（χ²=0.350、0.516，P=0.554、0.472）。TaTME组与LaTME组1年OS分别为100.00%、93.75%，2年OS分别为96.87%、81.25%。两组1年OS比较，差异无统计学意义（χ²=0.516，P=0.472），TaTME组的2年OS显著高于LaTME组患者（χ²=4.402，P=0.036）。 结论与LaTME术相比，TaTME术治疗中低位直肠癌具有较高的安全性和有效性，且术后并发症较少，术后住院时间短，可以改善患者预后。     

腹腔镜经腹会阴直肠柱状切除术对直肠癌环周切缘状态影响的研究

目的探讨腹腔镜经腹会阴联合直肠柱状切除术(cylindrical abdominopedneal resection,CAPR)对直肠癌环周切缘(circumferential resection margin,CRM)状态的影响。方法回顾性分析2009年1月至2013年6月收治的47例低位直肠癌患者的病理及临床资料,其中27例患者行传统经腹会阴联合直肠癌切除术(abdominopedneal resection,APR),20例患者行CAPR手术,比较CRM与临床病理特征之间的关系。结果 CRM总体阳性率为25.3%(12/47)。其中,肿瘤直径≥5cm组CRM阳性率(36.7%,10/17)明显高于肿瘤直径5cm组(5.9%,2/18)(χ2=4.417,P=0.036);在肿瘤分化程度方面,高分化组(11.1%,2/18)、中分化组(16.7%,2/12)、低分化组(47.1%,8/17)之间的CRM阳性率差异具有统计学意义(χ2=6.608,P=0.037);肿瘤下缘距肛缘距离≤3cm组CRM阳性率(38.5%,10/26)明显高于距离3cm组(9.5%,2/21)(χ2=5.116,P=0.024)。CAPR手术明显比APR手术具有较低的CRM阳性率[10%(2/20)v 37%(10/27);χ2=4.416,P=0.036]和直肠穿孔率[0(0/20)v 25.9%(7/27);χ2=2.219,P=0.04]。结论与APR手术相比,CAPR手术能降低CRM阳性率和术中直肠穿孔率。     

中低位直肠癌系膜浸润程度的临床研究

目的探讨中低位直肠癌直肠系膜浸润程度与临床病理特征及预后的关系。方法采用大组织切片技术,测量行全直肠系膜切除术的49例中低位直肠癌标本的肿瘤浸润深度及直肠系膜厚度,计算直肠系膜浸润程度;并分析其临床病理特征和随访结果。结果本组中低位直肠癌术后局部复发率为12．2％（6／49）,远处转移率为26．5％（13／49）。直肠癌直肠系膜浸润程度Ⅰ度20例（40．8％）,Ⅱ度13例（26．5％）,Ⅲ度16例（32．7％）,Ⅰ、Ⅱ、Ⅲ度者术后局部复发率分别为0、7．7％和31．3％（X^2=7．357,P=0．015）;远处转移率分别为10％、23．1％和50％（X^2=7．405,P=0．025）;5年生存率则分别为90．9％、69．2％和28．6％（p=0．013）。直肠系膜浸润程度与肿瘤直径（X^2=6．849,P=0．033）、T分期（X^2=34．845,P=0．000）、N分期（X^2=17．266,P=0．002）有关。结论直肠系膜浸润程度是影响直肠癌预后的重要因素。     

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.     

A comparison of the inhibitory effects of four volatile anaesthetics on the metabolism of chlorzoxazone, a substrate for CYP2E1, in rabbits

Background: Halothane inhibits in vitro and in vivo activity of cytochrome P-450 (CYP) 2E1. There are several fluorinated volatile anaesthetics besides halothane, and most of them are defluorinated by CYP2E1. It is unclear whether other fluorinated anaesthetics inhibit the in vivo activity of CYP2E1.
Methods: We compared the inhibitory effects of therapeutic concentrations of four inhalational anaesthetics, halothane, enflurane, isoflurane, and sevoflurane, on chlorzoxazone metabolism in rabbits receiving artificial ventilation.
Results: All four inhalational anaesthetics decreased arterial blood pressure and increased plasma chlorzoxazone concentration. However, no significant differences in the plasma chlorzoxazone concentration were found between the four anaesthetics. The estimated chlorzoxazone clearance increased after beginning inhalation with all four agents, but no significant difference in clearance was noted between agents.
Conclusions: At therapeutic concentrations, the in vivo inhibitory effect on chlorzoxazone metabolism was similar for all four inhalational anaesthetics examined, even though their chemical characteristics and extent of hepatic metabolism differ considerably.     

A Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

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.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

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.     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

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.