骶髂贯穿螺钉/骶髂关节螺钉治疗骨盆后环骨折的临床研究：新设计的点对点体外导向器的应用

目的 探讨新设计的点对点体外导向器在骶髂贯穿螺钉/骶髂关节螺钉治疗骨盆后环骨折中的应用,及其准确性和安全性。方法 前瞻性地纳入2017年6月至2018年6月我科收治的骨盆后环骨折病人共12例,其中男5例,女7例,年龄为（45±13）岁（23~76岁）。采用随机数字表法分组,其中6例病人纳入研究组,使用点对点体外导向器辅助骶髂贯穿螺钉/骶髂关节螺钉固定骨盆后环骨折;另6例病人设置为对照组,由同一术者在“C”型臂X线机透视下徒手置入螺钉;12例病人均只置入1枚骶髂贯穿螺钉或骶髂关节螺钉。记录每例手术从开始透视到置入螺钉的操作时间、术中透视次数及其置钉位置、并发症等。结果 两组术后的骨盆入口位、出口位和侧位影像资料显示,所有螺钉置入位置满意,术后无血管神经损伤并发症发生。研究组和对照组的操作时间分别为（32±11） min、（49±19） min,两组的透视次数分别为（25±8）次、（52±16）次,两组间比较,差异均有统计学意义（P=0.001,P=0.014）。结论 在点对点体外导向器的辅助下置入骶髂贯穿螺钉/骶髂关节螺钉治疗骨盆后环骨折,操作便捷,设计合理,螺钉置入准确、质量高,并可明显减少术中透视下的操作时间及透视次数。     

标准骶骨侧位像上骶神经根管前缘线对置入骶髂螺钉的作用

目的：了解骶神经根管于S1、S2骶段内的方位、走行,探讨标准骶骨侧位像上骶神经根管前缘线对置入骶髂螺钉的作用.方法：将全骨盆2.0 mm层厚轴向平扫数据导入到Mimics 10.0,并应用其分别将骶骨、双侧无名骨、骶管及骶神经根管制作成3D图像并旋转至标准骶骨侧位及骨盆出入口位后观察骶神经根管的方位、走行.辨识标准骶骨侧位及骨盆出入口位X线片上骶神经根管并观察其特点.结果：在S1、S2骶段内骶神经根管始于同节段椎管的头端前缘的两侧,止于同节段骶前孔,其走行由头端、后方、内侧至尾端、前方、外侧;在X线片上其密度低,尤其在标准骶骨侧位像上常仅其前缘线显像且多有中断现象而需要仔细辨识.结论：在标准骶骨侧位像上辨识骶神经根管前缘线并以之作为骶髂螺钉安全通道的尾后界,则可以避免内置物进入神经根管及骶管,从而提高置钉的安全性.     

双平面骨科机器人系统辅助骶髂关节螺钉置入的实验研究

目的本研究应用双平面骨科机器人系统进行尸体骨骨盆骶髂关节螺钉置入的实验研究,评估该系统的安全性和有效性。方法双平面骨科机器人系统是由北京航空航天大学和北京积水潭医院联合开发的一种基于术中X线图像的手术导航系统。在该系统辅助下对4具尸体骨骨盆进行骶髂关节螺钉置入,共12枚空心钉,均置入S1。作为对比,由同一位医生操作,应用传统方法在C型臂透视控制下对模型骨盆进行骶髂关节螺钉置入,同样为12枚空心钉。记录从采集图像到置入空心钉导针所需透视的次数、透视累计时间及操作时间,并进行统计学分析。置入骶髂关节螺钉后,通过目测、透视和锯开骶骨直接测量的方法检查螺钉的位置。结果在机器人导航辅助下,置入一枚导针的平均透视次数是2.5次,平均透视累计时间为1.5s,平均操作时间为253s;12枚骶髂关节螺钉均在安全区内。在透视控制下徒手操作,置入每枚导针的平均透视次数是20.3次,平均透视累计时间为13.7s,平均操作时间为246s;12枚骶髂关节螺钉中,两枚螺钉误置。应用双平面骨科机器人系统辅助操作的透视次数和透视累计时间少于徒手操作,二者差异有显著性意义(P<0.05)。而操作时间二者差异无显著性意义(P>0.05)。结论双平面骨科机器人系统为骶髂关节螺钉置入提供精准的空间定位和稳定的路径导航,而这一切都在短短的数分钟之内完成,具备极好的安全性和高效性,并使患者和医生受到的X线照射量显著减少。目前的应用结果鼓舞我们进一步的临床实验应用。     

应用入口位和出口位X线监视下经皮微创螺钉内固定治疗骶髂关节骨折脱位

[目的]探讨利用入口位和出口位x线引导下经皮螺钉内固定治疗骶髂关节骨折脱位的方法.[方法]选择旋转垂直不稳定的C型(Tile分型)骨盆骨折患者6例,术中利用入口位和出口位X线监视定位S1椎体的进针方向和位置,在X线监视下打入导针于合适位置,置入松质骨螺钉.[结果]6例骶髂关节骨折脱位均复位,术后X线及CT示螺钉固定位置良好.[结论]术中应用入口位和出口位投照即可准确地置入骶髂关节螺钉.该方法较传统方法减少了投照位置和投照次数,简化手术过程,为微创固定骶髂关节提供了新方法.     

骶髂关节螺钉治疗后骨盆骨折脱位

目的 探讨骶髂螺钉内固定术治疗骶髂关节脱位的效果。方法 患者术前进行肠道准备，术中俯卧位，切开显露髂骨外骨面，钻入克氏针，以X线透视正侧位以确定克氏针的位置，将φ6.5mm适当长度的中空松质骨拉力螺钉植入S1.2椎体，术后行康复训练。结果 术后随访6-14个月，7例患者术后无一例骨盆感染，无周围神经损伤，1例骶髂关节复位不佳，移位1.5cm，1枚螺钉误入邻近椎体，幸未产生后遗症。结论 骶髂拉力螺钉固定后骨盆环的技术具有操作较简单，固定可靠，创伤小，失血少，有利于患者康复等优点，骶髂螺钉并发症包括固定失败，置位不当，神经损伤，感染，后骨盆复位不佳等。     

骶骨相关解剖参数的CT影像学测量研究

目的:探讨骶骨解剖参数CT测量了解新型骶骨蝶形钢板DenisⅠ区安全置钉通道。方法：回顾性分析2020年1月至2020年6月正常成年骶骨CT资料101例,女49例,男52例,年龄（49.11±15.02）岁。重建骶骨三维模型,根据所需测量平面重新分割三维模型,并进行数据测量及统计分析。结果：骶骨上关节突下缘至S₂骶后孔下缘的竖直距离为（42.55±4.73） mm;S₁、S₂、S₃孔平面骶外侧嵴至骶髂关节面的水平距离依次为（19.09±3.07） mm、（15.34±2.69） mm、（8.29±2.48） mm;S₁孔平面由骶外侧嵴向前进钉,内侧角、外侧角为（7.49±7.49）°、（24.07±4.89）°;S₂孔平面内侧角、外侧角为（-3.10±8.95）°、（24.95±5.74）°。不同性别间除S₁水平距离、S₁内侧角外其余差异均有统计学意义,年龄与所有数据均无相关性。结论：新型骶骨蝶形钢板在DenisⅠ区有足够的安全置钉范围;成年人骶骨形态间存在差异,差异主要与性别相关而与年龄无关。     

仰卧位经皮骶髂置钉固定术治疗骨盆后环损伤

目的 探讨仰卧位经皮骶髂置钉固定术治疗骨盆后环损伤的可行性、手术方法及疗效.方法 在10具尸体操作的基础上,2004年10月至2007年10月对14例骨盆后环损伤行仰卧位经皮骶髂置钉固定术.男7例,女7例;年龄28～75岁,平均41.6岁.Tile B型损伤4例,C型损伤10例.患者仰卧位,于"C"型臂X线机透视下以髂前上棘上2 cm与腋后线交点及髂前上棘与髂后上棘连线中、后1/3交点为进钉点,若两点距离较大,则在透视下确定最佳进钉点.进钉角度为向前20°～30°角,向尾端倾斜5°～15°.经皮骶髂置入一枚直径7.2 mm空心钛螺钉固定.术后摄骨盆正位、骶骨侧位X线片,并行骶髂关节CT扫描,观察螺钉在S1椎体的位置.结果 14例均获随访,平均随访16个月.术后3个月骨盆骨折均临床愈合.14例共置入15枚空心钛螺钉,未发生与置钉有关的并发症.随访期间无神经损伤、螺钉松动及断裂现象,无骨盆畸形及骶髂部疼痛.Majeed疗效评定标准优良率为92.9%.结论 采用体表双定位法,可提高仰卧位骶髂置钉固定术的安全性;仰卧位经皮骶髂置钉固定术治疗骨盆后环损伤方便、可行.     

基于CT图像解剖学测量和数字重建透视的经皮骶髂螺钉固定术中透视方法研究

目的 基于CT图像对骶髂螺钉置入所涉及的重要解剖边界进行测量和分析,并应用数字重建透视(DRR)技术探讨术中获取理想透视图像的方法. 方法 收集30例患者的平卧位骨盆CT 扫描数据,使用三维重建技术,在图像中确定骶髂螺钉在S1椎体内安全通道的上方、前方和后方骨皮质边界,螺钉在骶孔区的前方、下方骨皮质边界,以及骶骨翼斜坡.测量这些边界与骨盆前后位垂线(基准线)在矢状面的夹角.应用DRR技术,确定透视人口位、出口位和侧位的理想拍摄角度,并观察关键解剖标志的特征性表现,分析术中标准透视图像的采集方法. 结果 S1椎体的上方、前方、后方骨皮质与基准线在矢状面的夹角平均分别为37.7°±8.6°(23.2°～50.8°)、22.9°±6.7°(13.1°～ 32.O°)、41.9°±6.8°(33.0°～54.8°),骶孔区的前方、下方骨皮质切线与基准线的夹角平均分别为37.0°±12.0°(19.9°～ 63.1°)、38.8°±8.0°(25.7°～ 54.6°),骶骨翼斜坡与基准线的夹角平均为82.4°±13.0°(70.3°～117.3°).通过基于DRR技术的透视模拟和对相应解剖结构的观察,可以得到拍摄标准入口位、出口位和侧位的透视方法,并能清楚显现各图像上的相应解剖标志. 结论 本研究所测得的数据个体差异较大,临床上应该根据每例患者的实际情况,并以相关解剖标志的特征性表现为依据,决定术中骨盆入口位和出口位的透视角度.为防止骶髂螺钉穿出斜坡伤及Ló神经和髂血管,需要从骨盆侧位透视图像上确认螺钉位置.     

儿童S2髂骨螺钉置钉可行性分析及钉道规划

目的:利用计算机三维重建及模拟置钉技术评估S₂髂骨螺钉在国人儿童应用可行性,且优化测量其钉道参数。方法:选取2018年12月至2020年12月行骨盆CT扫描且年龄5~16岁的儿童骨盆影像学资料83例,排除骨折、畸形、肿瘤等情况,其中男44例,女39例,年龄(10.66±3.52)岁,依据年龄分为4组(A组5~7岁;B组8~10岁;C组11~13岁;D组14~16岁)。将获得的原始CT数据导入Mimics软件中,三维重建骨盆骨性结构,并在三维视图模拟分别以螺钉最大头倾角、最小头倾角置入直径6.5 mm S₂髂骨螺钉。随后在3-Matic软件中分别测量最大头倾角和最小头倾角下螺钉冠状位夹角、矢状位尾倾角、横断位外展角、置钉总长度、骶骨内螺钉长度、髂骨宽度、进钉点距皮肤距离。比较分析不同年龄段儿童S₂髂骨螺钉置钉参数间的差异及性别与左右侧别间差异。结果:83例儿童均可置入直径6.5 mm S₂髂骨螺钉。各置钉参数左右侧别间比较,差异无统计学意义(P>0.05)。5~7岁儿童螺钉冠状位角度小于其他年龄段(P<0.05);但在螺钉矢状位角度上,在螺钉最大头倾角下5~7岁儿童可获得较大角度,但在最小头倾角下较大角度获得年龄组为11~13岁。螺钉横断位角度各年龄组差异无统计学意义(P>0.05)。5~7岁男童在最大头角下的冠状位角度和最小头倾角下的矢状位角度均大于女童(P<0.05);8~10岁女童最小头倾角下的冠状位角度大于男童(P<0.05);其余置钉角度参数男女性别间差异均无统计学意义(P>0.05)。各年龄组间,髂骨最小宽度、最长钉道距离及骶骨内螺钉长度差异随年龄增长,均呈增长趋势(P<0.05)。5~7岁及8~10岁女童皮肤距离均大于男性(P<0.05)。男童在14~16岁髂骨最小宽度宽于同阶段女童(P<0.05)。而5~7岁及11~13岁女童,最长钉道距离长于同阶段男童(P<0.05)。结论:5~16岁儿童骨盆可安全容纳直径6.5 mm S₂髂骨螺钉置入,但是由于儿童骨盆骨性结构处于发育生长时期,需精准评估,规划合理钉道、选择合适螺钉长度。     

拉力螺钉固定技术在骨盆后环损伤中的临床应用

目的探讨应用拉力螺钉固定技术治疗骨盆后环部损伤的适应证、手术方法及疗效。方法1998年8月至2005年12月，对47例骨盆骶髂结构复合损伤患者分别采用后侧经骶髂关节的拉力螺钉固定方法，后侧跨骶骨的髂-髂拉力螺钉固定方法及骶-髂拉力螺钉加髂：髂拉力螺钉固定方法治疗骨盆后环损伤，男31例，女16例；年龄18～53岁，平均32岁。通过影像学检查明确47例患者有60侧骨盆骶髂结构复合损伤。按照AO骨盆环损伤方法分型：B型损伤20例，其中B2型9例，B3型11例；C型损伤27例，其中C1型8例，C2型12例，C3型7例。患者麻醉后取俯卧位，行闭合或开放复位后用拉力螺钉固定。所有操作均在C型臂X线机透视下进行。结果47例患者均获随访，随访时间6个月至6年6个月，平均27．7个月。平均手术时间为80min。47例共置入骶髂拉力螺钉104枚。患者在术后2～3个月双下肢可完全负重行走，并逐渐恢复体力劳动。仅发生3枚螺钉松动，未发生神经损伤及螺钉断裂等并发症，腰骶及下肢活动接近正常。结论拉力螺钉固定技术可使不稳定性骨盆后环获得良好的即刻复位和固定，恢复骨盆环的稳定性，适用于骶髂关节脱位及骶骨骨折患者。     

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.     

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.