应用新型Vessel-X骨材料填充器注射聚甲基丙烯酸甲酯的实验研究

目的 探讨新型Vessel-X骨材料填充器对注射聚甲基丙烯酸甲酯(PMMA)在椎体内分布影响及对椎体力学性能的修复效果.方法 将新鲜冰冻人椎体标本14个随机分单侧穿刺和双侧穿刺组.每组7椎.测量各标本的骨密度、前后缘和中线高度以及原始刚度和强度后,建立压缩骨折模型.测量骨折后标本的高度和剐度.应用Vessel-X骨材料填充器注射PMMA后再次测量椎体的高度、强度和刚度.观察填充器在椎体内的膨胀情况及PMMA在椎体内的分布情况.结果 两组椎体术后的强度均较原始大,但术后强度比较差异无统计学意义.两组椎体术后刚度较骨折后水平均有恢复,双侧组较单侧组刚度恢复效果好.术后椎体各部位的高度均增加,但未恢复到原始高度水平.术后两组椎体中线两侧的高度差比较差异无统计学意义.轴位透视下见骨水泥在椎体内呈椭圆形或长椭圆形分布,与填充器在体外膨胀后的形状相似.横断标本后,见填充器能在椎体内良好膨胀,包裹绝大部分PMMA,仅少量PMMA渗漏到网层外,但均局限在网层周围.结论 Vessel-X骨材料填充器在椎体标本内能包裹绝大部分PMMA,可防止骨水泥渗漏,且能恢复骨折椎体的力学性能和高度.     

球囊骨扩张器与Sky骨扩张器在经皮椎体后凸成形术中应用的比较研究

目的比较球囊扩张经皮椎体后凸成形术（PKP）与Sky骨扩张器PKP的临床应用结果及优缺点。方法2004年10月至2006年2月分别应用球囊骨扩张器（球囊组）与Sky骨扩张器（Sky组）,对49例患者86个椎体行PKP,其中Sky组24例29个椎体,球囊组25例57个椎体。记录手术时间、术中出血量、骨水泥注射量,观察患者手术前后疼痛和功能改善情况,观察骨水泥在椎体内的分布以及病椎的高度改变。结果所有患者均安全完成手术。以平均每个椎体计算,两组手术时间、出血量、器械材料费用相比较,差异均无统计学意义（P〉0．05）。球囊组平均每侧注入PMMA骨水泥的量较Sky组多（P〈0．05）。两组患者术后VAS和ODI评分均较术前减少（P〈0．05）。X线片观察：球囊组单侧穿刺的32个椎体有24个见骨水泥越过中线到达椎体对侧;Sky组单侧穿刺的28个椎体见骨水泥主要局限在穿刺侧,有6个椎体见少量骨水泥越过中线到达椎体对侧。两组病椎高度均有不同程度的恢复,球囊组椎体前缘和中线高度恢复较明显,Sky组以椎体中线高度恢复较明显。球囊组有4例5个椎体出现椎间隙少量渗漏。Sky组中出现椎间隙骨水泥少量渗漏5例7个椎体,椎体后缘渗漏3例3个椎体,椎旁少量渗漏1例1个椎体。Sky骨扩张器5例退出困难,1例断裂。1例球囊在扩张第3个椎体时破裂。结论球囊扩张PKP与Sky骨扩张器PKP治疗疼痛性压缩骨折均有良好的临床疗效;Sky骨扩张器PKP在单节段椎体中选用较好,球囊扩张PKP对多节段椎体骨折更为适用。     

椎体后凸成形术中单球囊交替扩张与双球囊同时扩张治疗骨质疏松性椎体骨折的疗效对比

目的 对比单球囊交替扩张与双球囊同时扩张椎体后凸成形术（PKP）治疗骨质疏松性椎体骨折的临床疗效.方法 54例骨质疏松性椎体骨折患者,按手术方法不同分为单球囊组（30例）和双球囊组（24例）,对比两组患者的手术时间、术中出血量、骨水泥注射量及疼痛视觉模拟评分（VAS）、Cobb角、椎体高度,评价其疗效.结果 单个椎体手术时间、骨水泥注射量及术中出血量两组比较差异均无统计学意义（P〉0.05）;手术前后VAS评分、Cobb角及椎体前缘高度、中央高度及后缘高度两组比较差异均无统计学意义（P〉0.05）.两组术后VAS评分及Cobb角均较术前明显改善（P〈0.05）;两组术后椎体前缘高度与中央高度均较术前提高（P〈0.05）,但后缘高度并未发生明显的变化（P〉0.05）.结论 单球囊交替扩张与双球囊同时扩张PKP治疗骨质疏松性椎体骨折均能够获得较好的疗效,但在患者经济情况允许的情况下,双球囊扩张术应是首选术式.     

PKP术中不同比例灌注骨水泥椎体生物力学分析

目的 利用乙二胺四乙酸二钠（EDTA-Na2）脱钙法制备离体椎体骨质疏松模型,在万能材料试验机上垂直压缩制成椎体压缩骨折模型,行椎体后凸成形术（percutaneous kyphoplasty,PKP）后再进行生物力学实验,分析按照球囊扩张容积的不同比例灌注骨水泥后椎体的生物力学性能变化,为临床治疗提供参考性资料.方法 选取新鲜成年猪胸腰段椎体36个,甲醛浸泡24 h,再以EDTA-Na2脱钙20 d,制成骨质疏松椎体模型,随机分成A、B、C、D4组,每组9个椎体,检测各组椎体骨矿密度,并依次放在万能材料试验机上行垂直压缩,测出椎体最大压缩强度及压缩刚度,记录各组椎体压缩前、后的椎体前缘高度.之后将各组分别进行聚甲基丙烯酸甲酯灌注椎体成形,按照球囊扩张容积的不同比例灌注聚甲基丙烯酸甲酯,记录球囊扩张容积、球囊压力、成型后椎体前缘高度及骨水泥渗漏椎体个数.之后进行第二次加载测试,按初始方法压缩椎体,记录此时椎体最大压缩强度和刚度.结果 PKP前四组间的椎体前缘高度、骨密度、椎体最大压缩强度及压缩刚度均无统计学意义（P＞0.05）;各组在PKP前、后的椎体最大压缩强度和压缩刚度的比较有统计学意义（P＜0.01）;PKP后A、B组间的椎体最大压缩强度和刚度比较无统计学意义（P＞0.05）,A、B两组分别与C、D组间的椎体最大压缩强度和刚度的比较有统计学意义（P＜0.01）;PKP后四组间椎体高度恢复值比较无统计学意义（P＞0.05）;A、B两组的骨水泥渗漏率为0,C、D两组的骨水泥渗漏率分别为22.22%及44.44%.结论 PKP中按照球囊扩张容积的0.8～1倍灌注骨水泥即可有效恢复骨质疏松性压缩骨折椎体的生物力学性能,又能减少骨水泥的渗漏;PKP中按照球囊扩张容积的0.8～1倍灌注骨水泥可以部分恢复压缩椎体的高度,其与高比例灌注组无明显差别;球囊扩张容积可以作为PKP中骨水泥灌注剂量的参考指标.     

单球囊双侧序贯扩张椎体后凸成形术预防复位椎体再塌陷

[目的]探讨单个球囊双侧序贯扩张椎体后凸成形术预防复位椎体术中再塌陷的有效性。[方法]纳入2016年1月~2016年12月收治的80例骨质疏松性椎体骨折患者,随机分成两组,每组40例。双侧组采用单球囊双侧序贯扩张椎体后凸成形术,单侧组采用单个球囊单侧扩张椎体后凸成形术。记录两组围手术期资料,采用疼痛视觉模拟评分(VAS),Oswestry功能障碍指数(ODI)和影像测量评估临床效果。[结果]双侧组的手术时间、X线暴露时间、骨水泥注入量均显著大于单侧组,但差异有统计学意义(P0.05)。双侧组的骨水泥渗漏率低于单侧组,但差异无统计学意义(P0.05)。双侧组的骨水泥弥散面积率明显高于单侧组,差异有统计学意义(P0.05)。两组患者术中球囊扩张后椎体前缘高度的差异无统计学意义(P0.05);但球囊取出后的椎体前缘高度双侧组高于单侧组,差异有统计学意义(P0.05)。双侧组术后1 d的椎体前缘高度大于单侧组,而椎体后凸角小于单侧组,差异均有统计学意义(P0.05)。两组患者术后1 d的VAS、ODI差异无统计学意义(P0.05)。术后12个月,双侧组椎体前缘高度仍显著大于单侧组,差异有统计意义(P0.05);此时两组椎体前缘高度均较术后1 d时减少,差异有统计学意义(P0.05)。[结论]单个球囊双侧序贯扩张椎体后凸成形术能较好的恢复椎体高度,有效预防复位椎体术中再塌陷。     

不同入路经皮椎体后凸成形术的体外力学研究

目的比较不同入路经皮椎体后凸成形术(PKP)对伤椎复位效果及恢复其力学性能的差异。方法选择成年男性防腐脊柱标本的T7至L4节段, 将单体椎体标本随机分为单侧弯角入路组(A组)、单侧经椎弓根入路组(B组)、单侧斜行入路组(C组)、双侧经椎弓根入路组(D组)(n=10)。测量椎体前、后缘高度, 测算并比较椎体容积。在生物力学机上建立骨质疏松性椎体压缩骨折(OVCF)模型后测量椎体前、后缘高度, 并分别对4组标本完成不同入路PKP。对椎体进行Micro-CT检查, 测量术后椎体前、后缘高度。记录椎体原始强度、原始刚度, 造模后刚度, 术后强度, 术后穿刺侧、对侧及总体刚度。比较各组在椎体内骨水泥灌注量, 前、后缘高度恢复, 强度、刚度变化的差异。结果 4组椎体容积比较差异无统计学意义(P>0.05);D组骨水泥灌注量显著多于其他3组, 差异均有统计学意义(P<0.05)。椎体前、后缘高度恢复、原始强度、原始刚度、造模后刚度、术后总体刚度4组间比较差异均无统计学意义(P>0.05);4组术后强度与原始强度比较差异均无统计学意义(P>0.05);4组术后穿刺侧刚度及A、D...     

单球囊单侧和双侧扩张椎体后凸成形术临床疗效评价

摘要：目的评价单球囊单侧和双侧交替扩张椎体后凸成形术治疗骨质疏松性压缩骨折的临床效果。方法2010年4月至2011年5月应用单球囊单侧和双侧交替扩张椎体后凸成性术治疗骨质疏松性压缩骨折患者2l例21椎,分为单侧球囊扩张组12椎和双侧球囊扩张组9椎,两组均经椎弓根入路,分别采用单球囊单侧扩张和双侧交替扩张的方法。比较两组术前、术后的椎体压缩率,术前、术后VAS评分,术后骨水泥左右侧分布面积比值。结果患者术后疼痛均明显减轻或消失。单侧组VAS评分由术前平均7．17±1．12分改善为术后平均2．67±0．89分,双侧组由术前平均7．50±0．85分改善为3．11±0．60分;单侧组椎体压缩率由术前平均32．3％±12．6％矫正为术后平均27．8％±13．1％,双侧组由术前平均32．9％±15．5％矫正为术后平均28．2％±14．2％;单侧组术后左、右侧骨水泥分布面积比值平均为0．96±0．16,双侧组比值平均为0．98±0．15,均无统计学差异（P〉0．05）。结论椎体后凸成形术能有效缓解椎体骨质疏松性压缩骨折患者的疼痛,不同程度恢复椎体高度,改善后凸畸形;单球囊单侧和双侧交替扩张椎体后凸成形术同样使压缩骨折的椎体获到较好复位。     

对比单侧与双侧PKP治疗骨质疏松性胸腰椎压缩性骨折的疗效

目的对比单侧与双侧经皮穿刺球囊扩张椎体后凸成形术（PKP）治疗骨质疏松性胸腰椎压缩性骨折的疗效。方法对于骨质疏松性胸腰椎压缩性骨折行双侧椎体成形术15例,单侧椎体成形术18例。结果对于行单侧椎体成形术与双侧椎体成形术后的患者随访12～48月,行单双侧PKP术后的指标与术前对比,VAS与术前比较差异有统计学意义（P〈0.01）。结论行单侧与双侧椎体成形术能有效的缓解骨质疏松性胸腰椎压缩性骨折导致的疼痛,并部分恢复病椎的高度,可改善脊柱的功能。     

单侧PKP骨水泥注射过中线分布对压缩性骨折椎体两侧刚度的影响

目的:评价单侧椎体后凸成形术(PKP)中骨水泥注射超越椎体中线与否对椎体轴向及两侧刚度的影响。方法:3具防腐成人胸腰椎椎体标本(T4～L1)用于实验。通过MTS平台给椎体施加轴向压力,制作压缩性椎体骨折模型,同时进行球囊辅助下经单侧椎弓根穿刺椎体后凸成形术,根据骨水泥是否过椎体中线分为两组,骨水泥注射不过椎体中线(A组,n=9);骨水泥注射过椎体中线(B组,n=8),骨水泥注射量为椎体体积的10%。24h后放置在MTS-858材料实验平台上,给标本分别施加0～300N轴向和侧方压力载荷,记录并比较骨水泥注射术后,两组椎体轴向及两侧的刚度差异。结果:轴向压缩载荷下,A组与B组间轴向压缩刚度无显著差异(P>0.05);在椎体侧方压缩载荷下,尽管A组椎体骨水泥穿刺侧的刚度与B组间差异无显著性(P>0.05);但在非穿刺侧刚度上,B组显著高于A组,差异有显著性(P<0.05)。结论:行单侧PKP时,若骨水泥填充不过椎体中线时,则非穿刺侧刚度明显低于穿刺侧,而骨水泥填充过中线时,则两侧椎体刚度可同时得到显著强化。     

骨水泥单侧与双侧分布对椎体后凸成形术疗效影响

目的探讨骨水泥单侧与双侧分布对椎体后凸成形术治疗骨质疏松性椎体压缩骨折临床疗效的影响。方法对42例骨质疏松性椎体压缩骨折患者经单侧穿刺行经皮椎体后凸成形术,依据骨水泥是否过中线分布分为两组,单侧组12例(12个椎体),双侧组30例(30个椎体),观察两组手术前后VAS评分、椎体平均高度、局部Cobb角以及术椎、非术椎椎体再骨折发生情况。结果单侧组与双侧组术后及随访时VAS评分均较术前明显降低(P0.05),组间比较差异无统计学意义(P0.05);术后两组椎体平均高度及局部Cobb角较术前均有显著恢复(P0.05),组间比较差异无统计学意义(P0.05);两组邻近椎体再骨折的发生率比较差异无统计学意义(P0.05),而术椎椎体再骨折比较差异有统计学意义(P0.05)。结论无论骨水泥是否过中线分布,均可取得有效的临床效果,且并未增加邻近椎体骨折的发生率;但单侧骨水泥分布有可能造成强化椎体再骨折;骨水泥过中线分布时临床疗效良好。     

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 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.     

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.     

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.