数字骨库的建立及其在骨肿瘤手术治疗中的应用

目的 建立数字化骨库,并探讨其在骨肿瘤切除同种异体骨重建中的临床应用价值.方法 采用薄层CT对现有骨库中的大段同种异体骨进行扫描,将所得断层数据输入自制的数字骨科管理软件,三维重建后建立数字化分析系统.利用数字化骨库找到匹配的骨重建材料,并在术前设计截骨范围和异体骨修整.2009年11月至2012年6月对11例骨肿瘤患者采用数字化骨库和计算机辅助导航技术进行手术治疗,男7例,女4例;年龄13 ～42岁,平均24.7岁;其中骨巨细胞瘤3例,骨肉瘤5例,软骨肉瘤2例,尤文氏肉瘤l例.术后复查患处X线片并采用肌肉骨骼肿瘤学会93(MSTS93)评分系统评价肿瘤学结果和功能恢复情况. 结果 应用数字化骨库可以明显缩短异体骨材料的选配时间,并明显提高异体骨选配的精确性.使用计算机辅助导航进行肿瘤切除大段同种异体骨重建,术前CT三维虚拟影像与实际解剖注册点匹配满意,注册误差平均为0.42 mm.11例患者术后随访3～30个月,平均15.7个月;术后复查影像可见肿瘤切除范围与异体骨重建区域与术前计划完全吻合,肿瘤切除范围安全,边界完整,无肢体不等长或畸形发生;未见局部复发和远隔转移,无内固定松动、断裂和关节塌陷,无明显免疫排异反应;异体骨与宿主骨愈合时间5～7个月,平均6.3个月.MSTS93功能评分平均为25.7分. 结论 建立的数字化骨库可在术前精确选择同种异体骨并完成手术设计,结合计算机辅助导航技术可实现骨肿瘤切除、大段同种异体骨重建的个体化设计,可有效提高骨肿瘤手术治疗的安全和疗效.     

导航辅助髋臼肿瘤切除与个体化定制假体重建

目的 探讨计算机导航辅助髋臼周围肿瘤精确切除与个体化定制假体重建的效果. 方法 选取1例左侧骨盆软骨肉瘤切除术后复发患者,男,55岁,二次术前行CT和MRI检查,利用三维图像融合技术判断髋臼周围肿瘤侵袭范围,确定外科边缘及截骨平面,根据截骨后骨盆缺损范围利用计算机辅助设计与制造(CAD/CAM)技术设计并定制个体化髋臼假体.术前将CT数据、标记的截骨范围及假体安装参数导入导航系统中进行规划,术中在导航引导下精确切除肿瘤并验证切除边界的准确性,继而在导航辅助下完成个体化定制假体的精确安装,验证假体的匹配程度.切除标本后送病理学检查,测量患肢长度变化,并参照肌肉骨骼肿瘤学会93(MSTS 93)功能评分标准评定关节功能. 结果 三维图像融合技术可有效指导复杂区域肿瘤安全边界的确定.计算机导航辅助肿瘤切除和个体化定制髋臼假体重建能够满足髋臼肿瘤精准切除和重建的要求,切除边缘经病理学检查证实无肿瘤存在,导航验证及影像学证实假体安装准确,假体与截骨界面完美匹配,髋臼位置和角度理想.术后6个月假体在位良好、无松动,螺钉无断裂,肿瘤无复发、转移,无感染,MSTS93评分为16分.结论 综合利用计算机导航、图像融合、逆向工程、CAD/CAM可有效实现髋臼周围肿瘤的精确切除与个体化定制髋臼假体重建,实现手术目标.     

数字化骨库的建立及在骨肿瘤切除异体骨关节个体化重建中的应用

目的探讨数字化骨库建立的可行性,评价异体骨数字化对于导航下骨肿瘤切除异体骨重建的影响。方法采用CT扫描的方法,对骨库深低温冷冻保存的同种异体骨段进行扫描,通过三维重建建立数字化分析系统（数字化骨库）。利用数字化骨库,选择最佳匹配的骨关节重建材料,数据导人计算机导航系统,标定骨肿瘤切除和异体骨段的截骨范围,依据术前设计在导航下实施、监测。2009年11月至2011年11月,采用数字化骨库和导航辅助切除重建技术对6例关节周围恶性骨肿瘤进行治疗,患者平均年龄（27．2±9．1）岁,其中骨肉瘤3例,软骨肉瘤2例,尤文氏肉瘤1例;Enneking分期：ⅡA期2例,1IB期4例,术后评价肿瘤学结果和功能恢复情况。结果与常规异体植骨材料术前准备操作相比,数字化骨库建立后,大大缩短了异体骨关节材料的选配时间,同时明显地提高了选配的精确性。计算机导航辅助下进行肿瘤切除、异体骨关节切割以及关节力线监控,术中解剖注册点与CT三维虚拟影像匹配满意,注册误差（0．42±0．17）mm。术后影像显示肿瘤整块切除范围和异体骨关节截骨区域与术前计划完全一致,关节重建稳定,无肢体不等长和关节畸形。随访（19．3±0．7．1）个月,未见局部复发和远隔转移,无明显免疫排异反应,异体骨与宿主骨平均愈合时间（5．2±0．8）个月,无内固定松动、断裂和关节塌陷。MSTS93平均功能评分（26．2±4．1）分。结论数字化骨库的建立为术前选配同种异体骨材料提供了精细可靠的信息,结合计算机辅助导航,可以实现骨肿瘤切除异体骨关节重建的个性化设计要求,进一步提高保肢手术的安全性和效果。     

计算机导航辅助髋臼肿瘤精确切除与重建

目的 探索髋臼恶性肿瘤精确切除与重建的有效方法,评价其临床治疗效果.方法 利用图像融合、逆向工程、计算机辅助设计与制造等技术,建立髋臼恶性肿瘤精确切除与重建的治疗流程,完成术前规划并制备个体化定制髋臼假体,利用计算机导航系统辅助手术实施,实现肿瘤的精确切除及假体安装.自2010年12月至2012年5月,采用该流程治疗3例髋臼恶性肿瘤患者,软骨肉瘤2例、原始神经外胚层肿瘤1例,均累及骨盆Ⅱ+Ⅲ区.采用国际骨肿瘤协会(Musculoskeletal Tumor Society,MSTS)功能评分评价患肢功能,统计并发症发生情况.结果 3例患者均成功获得精确的肿瘤切除与髋臼重建.1例患者术后因搬动失误发生髋关节脱位,予以闭合复位;该例患者术后出现下肢深静脉血栓形成,对症治疗后治愈.术后3例患者均获得随访,随访时间10～21个月.至末次随访时3例患者均无瘤生存,未见感染、假体松动、螺钉断裂等并发症.MSTS评分为18～26分.结论 计算机导航辅助肿瘤切除和个体化定制髋臼假体重建能够满足髋臼肿瘤精确切除和重建的要求,肿瘤切除彻底、髋臼重建满意、并发症发生率低、近期效果良好,是外科治疗恶性髋臼肿瘤的一种有效方法,其远期疗效有待于进一步观察.     

计算机导航辅助下保留关节治疗肢体恶性骨肿瘤

目的 探讨应用计算机导航辅助下保留关节治疗肢体恶性骨肿瘤的意义. 方法 2008年 9 月至2011年3月,行保留关节人工假体和大段异体骨置换术治疗12例股骨远段、胫骨近段和胫骨远段恶性肿瘤患者,其中男7例女,5例;年龄12～59 岁,平均26.7岁,病变位于股骨远段干骺端8例,胫骨近段干骺端3例,胫骨远段骺端1例,骨肉瘤7例软骨,软骨肉瘤3例,血管内皮瘤1例,梭形细胞肉瘤1例 .术前采用增强CT和MRI在计算机导航工作站上设计术前方案,明确病灶侵犯的髓内范围和骨外范围,设计截除瘤骨的范围并标记,术中计算机导航指引下,注册定位,按术前设计截断瘤骨,保留关节及韧带组织,装配特制人工假体8例和大段异体骨置换4例. 结果 12例患者全部按术前计划完成手术,术后肿瘤标本经病理验证达到广泛切除.所有患者随访7～37个月,平均21个月.按肌肉骨与软组织肿瘤协会(MSTS)患肢功能评价体系评分,术后肢体功能恢复92％～96％,平均94％.术后无伤口及关节感染发生,无局部复发和远隔转移发生. 结论 计算机导航技术可以在术中精确实现术前设计的肿瘤外科切边界,避免盲目扩大肿瘤切除范围和损失重要的骨骼关节节结构从而为患肢关节结均重建创造条件,提高肢体功能恢复水平.     

计算机辅助恶性骨肿瘤个性化切除与精确重建

目的探讨计算机辅助恶性骨肿瘤个性化切除与精确重建的新方法,评价计算机辅助技术在恶性骨肿瘤手术治疗中的价值。方法 2007年1月～2010年7月共收治13例恶性骨肿瘤患者。其中男7例,女6例,年龄19～46岁。Enneking分期ⅡA期8例,ⅡB期5例。所有患者均采用薄层CT扫描获取病变部位的二维数据,重建三维解剖模型,运用计算机辅助设计（computer aided design,CAD）技术精确设计肿瘤切除范围、个性化辅助手术模板以及个性化骨修复体,模拟骨缺损修复重建过程。术中按照CAD方案精确切除肿瘤组织,采用外形匹配的异体骨或异体骨＋个性化人工关节置换重建骨肿瘤切除后遗留骨缺损。随访期间采用骨与软组织肿瘤学会（Musculoskeletal Tumor Society,MSTS）保肢评分系统对随访患者进行功能评价。结果 13例患者均获得随访,随访时间10～52个月,平均24.8个月。术后早期X线片显示骨缺损区域结构重建效果好,骨缺损区域解剖结构获得恢复。所有患者均存活,末次随访MSTS评分为17～27分,平均23.5分,其中优7例,良4例,可2例。2例发生异体骨感染,1例异体骨不愈合,1例钢板断裂,2例异体骨吸收。1例髋臼肿瘤术后18个月局部复发,行肿瘤再切除治疗。结论将计算机辅助技术用于骨恶性肿瘤的手术治疗,可以正确设计肿瘤切除边界、准确切除肿瘤并对病变区域的骨关节结构进行精确重建,从而将骨肿瘤手术治疗提升到个性化外科手术的高度。     

同种异体骨移植重建四肢恶性骨肿瘤切除后骨缺损

[目的]探讨同种异体骨移植修复重建四肢恶性骨肿瘤切除后骨缺损的临床疗效。[方法] 2013年6月～2017年12月对本院收治的21例四肢恶性骨肿瘤切除后骨缺损病例进行大段同种异体骨移植重建,其中复合肿瘤型人工关节置换12例,单纯异体骨段移植9例。本组病例男13例,女8例;年龄11～51岁,平均(21.53±6.54)岁,均经过术前穿刺活检及术后病理确诊,Enneking分期ⅠB期4例,ⅡB期17例,其中骨肉瘤和尤文肉瘤患者术前均行2个疗程新辅助化疗及术后规范化疗。术后采用MSTS评分进行功能评价。[结果]所有患者获随访8～48个月,平均(29.64±11.22)个月,均未发生移植异体骨或假体周围骨折,无关节脱位及假体松动。其中19例肢体功能优良,MSTS功能评分16～28分,平均(22.82±4.47)分。[结论]异体骨移植联合肿瘤型人工关节复合置换,以及异体骨段移植重建长骨干缺损仍然是治疗四肢恶性骨肿瘤切除后骨缺损的一种有效重建方法。     

数字骨库辅助异体骨选配在骨肿瘤中的应用及长期疗效观察

目的本研究旨在探讨一种数字骨库系统的建立及在异体骨选配中的应用,并观察其远期治疗效果。方法异体骨经过CT扫描后存储为医学数字影像交互格式。然后依据CT密度值进行图像分割和三维模型重建,建立数字骨库系统。基于体积参数将异体骨在数字骨库中进行登记。异体骨的选配及应用分别以1例骨盆尤文肉瘤和1例胫骨远端骨肉瘤患者的治疗过程为例进行阐述。采用计算机导航辅助手术,实现术中的精确切除与重建。结果通过数字骨库和计算机导航辅助,异体骨与骨肿瘤切除后骨缺损之间实现精确匹配。术后5年随访,肿瘤无局部复发或远处转移,功能效果满意。结论数字骨库系统有助于异体骨选配和骨肿瘤切除重建,可提高骨肿瘤保肢手术的疗效。     

计算机辅助骨盆肿瘤精确切除和功能重建

目的探讨计算机辅助设计(computer-aided design,CAD)在确定骨盆肿瘤切除边界、重建骨盆和髋关节结构中的应用价值。方法 2006年11月-2009年4月收治5例骨盆肿瘤患者。男3例,女2例;年龄24～62岁,平均36.4岁。骨肉瘤、骨巨细胞瘤、血管肉瘤各1例,软骨肉瘤2例。根据Enneking骨盆肿瘤分区:Ⅰ区、Ⅰ+Ⅱ区、Ⅲ区、Ⅳ区、Ⅰ+Ⅳ区各1例。按反求工程的基本原理,采用CT、MRI扫描获取患者骨盆二维数据,计算机三维重建建立骨盆解剖模型,将解剖模型输入CAD软件精确界定肿瘤切除范围,并设计个性化辅助手术模板、个性化假体以及模拟肿瘤切除、骨缺损修复重建过程。术中按照CAD方案精确切除骨盆肿瘤组织,采用外形匹配的同种异体髂骨加内固定或同种异体髂骨加个性化假体修复肿瘤切除后骨缺损,重建骨盆。结果 5例患者均顺利完成手术,手术时间平均7.9 h,术中出血量平均3 125 mL。术后1例出现切口内积血,1例出现脑脊液漏,均对症处理后痊愈。5例均获随访,随访时间24～50个月,平均34.5个月。患者均于术后4～6周扶双拐部分负重行走,3～6个月恢复行走功能。2例于术后18个月局部复发,1例行局部肿瘤再切除术、1例行局部放疗,无再复发。术后24个月采用国际保肢学会(ISOLS)推荐的骨肿瘤保肢术疗效评价标准进行功能评定,获优2例,良3例。结论采用CAD设计的个性化辅助手术模板、个性化假体及模拟手术过程,保证了骨盆肿瘤切除的精确性和可靠性,将骨盆肿瘤的切除和功能重建提升到个体化治疗阶段,可获得较好的疗效。     

半骨盆置换术治疗骨盆恶性肿瘤的中远期随访

[目的]探讨半骨盆置换术在骨盆恶性肿瘤广泛切除和功能性保肢手术中的应用.[方法]回顾本科自2003 ～2007年16例半骨盆切除和重建手术治疗案例,评估骨盆恶性肿瘤广泛切除和假体置换术的疗效和并发症.[结果] 16例骨盆原发性恶性骨肿瘤患者,接受了骨盆肿瘤切除和计算机辅助定制人工半骨盆假体置换手术.患者平均年龄为27岁,病理类型包括4例骨肉瘤、6例软骨肉瘤、3例骨巨细胞瘤、1例尤文肉瘤和2例纤维肉瘤,外科分期为ⅡB.术前评估包括:MRI、ECT全身骨扫描、肺部CT、肿瘤穿刺活检及动脉血管造影并根据病理结果部分行动脉灌注化疗,广泛切除骨盆肿瘤,安装定制人工半骨盆假体.术中平均出血2 600ml(1 200～8 500ml).5例有伤口并发症,脱位3例.中位随访时间36个月(23 ～62个月),3例局部复发行局部切除放疗,4例死于原发肿瘤远处转移,MSTS功能评分平均72％.[结论]在骨盆原发性恶性肿瘤的治疗中,合理的广泛切除是治愈肿瘤的关键,应用计算机辅助半骨盆假体置换能快速、有效重建骨骼缺损,原发肿瘤对化疗及放疗的敏感性及肿瘤的性质是决定预后的主要原因,伤口并发症及脱位是其主要并发症,患者心理满意度较高,患肢功能可以接受.     

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.     

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.     

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.     

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.     

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.     

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.