内侧支撑髓内钉和股骨近端抗旋髓内钉治疗股骨转子间骨折A3.3型的生物力学研究

目的：A3型股骨转子间骨折是极其不稳定的骨折,临床上常常采用髓内治疗,但是髓内固定失败率高,股骨后内侧结构不能重建是主要原因。介绍一种可以早期重建股骨内侧支撑的新型内侧支撑髓内钉,通过生物力学试验验证力学效果。方法：利用人工股骨模型（Sawbones）制作内侧失支撑的A3.3型转子间骨折模型,分别用新型内侧支撑髓内钉（medial sustainable nail-Ⅱ,MSN-Ⅱ）和股骨近端抗旋髓内钉（proximal femoral nail anti-rotation,PFNA-Ⅱ）固定后,行轴向加载和轴向破坏试验,测定两种内固定物的轴向刚度、屈服载荷、头颈骨块的位移和断端扭转角度,比较两种内固定的生物力学差异,明确重建内侧支撑的髓内钉早期重建股骨内侧支撑的效果。结果：MSN-Ⅱ的轴向刚度、屈服载荷、当轴向载荷为1 800 N时头颈骨块的位移、破坏试验后的骨折断端扭转角度分别为（222.76±62.46）N/mm,（4 241.71±847.42）N,（11.51±0.62）mm,（1.71±0.10）°;PFNA-Ⅱ分别为（184.58±40.59）N/mm,（3 058.76±379.63）N,（16.15±1.36）mm,（2.52±0.26）°,两组差异均有统计学意义。结论：MSN-Ⅱ轴向刚度优于PFNA-Ⅱ,在固定A3.3型骨折时能耐受更大的载荷,具有更大的轴向和旋转稳定性,是重建A3型股骨转子间骨折内侧支撑有效的手段。     

单侧与双侧钢板内固定治疗AO-A3型股骨远端骨折的试验研究

目的对单侧、双侧钢板内固定治疗干骺端粉碎性股骨远端骨折生物力学稳定性进行比较。方法笔者于2016-04—2016-06选取8个配对的经防腐处理的成人股骨标本,建立AO-A3型骨折模型,随机分为2组,单侧钢板组用外侧解剖锁定接骨板固定,双侧钢板组外侧用解剖锁定接骨板、内侧用直型接骨板固定。应用电子万能试验机对单侧与双侧钢板组进行生物力学检测,比较2组垂直加压、循环垂直加压及极限载荷下的稳定性。结果单侧钢板组在垂直加压、循环垂直加压及极限载荷测试中均劣于双侧钢板组,差异有统计学意义(P0.05)。2组未出现钢板或螺钉断裂,载荷-位移曲线斜率未发生较大变化。载荷去除后,2组均恢复原来的状态,具有较好的即刻稳定性。结论单侧或双侧钢板固定干骺端粉碎性股骨远端骨折均能达到有效的力学稳定性,一般无需双侧钢板固定来增加固定强度,单侧钢板固定弹性更佳,可能有利于骨折端的微动及骨折愈合。     

弹性髓内钉与接骨板内固定治疗儿童股骨转子下骨折的临床对照研究

目的 探讨弹性髓内钉与接骨板内固定治疗儿童股骨转子下骨折的临床疗效及相关优势。方法 回顾性分析2013年3月至2017年3月我院收治的100例股骨转子下骨折患儿,依据治疗方式的不同分成观察组（予以弹性髓内钉内固定术,50例）和对照组（予以接骨板内固定术,50例）。两组患儿术后均随访1年,比较两组患儿的手术时间、术中出血量、住院时间、骨折愈合时间及并发症的差异。采用Harris髋关节评分和美国特种外科医院（Hospital for Special Surgery,HSS）膝关节评分评定患肢髋、膝关节功能。结果 观察组术中出血量为（50.60±18.35） ml,住院时间为（6.75±4.40） d,骨折愈合时间为（56.50±3.85） d;对照组则分别为（55.30±18.95） ml、（6.80±5.75） d和（60.70±4.06） d,两组间上述指标的差异均无统计学意义（P＞0.05）。两组病人在随访期内骨折全部愈合,对位对线良好,关节功能正常。观察组1例出现弹性钉针尾刺激皮肤现象,经二次手术剪短弹性钉尾端后症状消失,对照组出现切口脂肪液化1例,经重新缝合痊愈。结论 弹性髓内钉和接骨板内固定均为治疗儿童股骨转子下骨折的有效方法,两种方法各有优缺点,手术治疗原则是稳定与微创相结合,在恢复股骨轴线及长度的同时,注意对血运保护以利于骨折愈合。     

锁定重建接骨板治疗髋臼横行骨折的生物力学研究

背景：髋臼横形骨折治疗较为困难,常采用内固定的治疗方法。近年来有学者尝试采用锁定重建接骨板,但对其的研究报道较少。 目的：比较4种不同锁定重建接骨板后方入路内固定方式治疗髋臼横行骨折的生物力学稳定性。 方法：采用成人防腐标本10具,制成髋臼横行骨折模型20个,随机分为4组,每组5个标本。A组：重建接骨板两端各固定3枚螺钉。B组：重建接骨板两端各固定3枚螺钉及距骨折线最近的两侧螺孔各1枚螺钉。C组：锁定重建接骨板两端各3枚单皮质螺钉。D组：锁定重建接骨板两端各3枚单皮质螺钉及距骨折线最近的两侧螺孔各1枚单皮质螺钉。行轴向的加载实验,记录内固定失效时最大负载和轴向刚度。 结果：A、B、C、D组所能承受的最大负载分别为（180.60±11.781）N、（240.80±7.981）N、（243.80±11.755）N和（438.00±23.227）N;轴向刚度分别为（95.21±6.32）N/mm、（123.47±23.95）N/mm、（126.39±18.52）N/mm和（227.35±13.74）N/mm。除B、C两组数据比较无统计学差异（P〉0.05）,其余各组的最大负载和轴向刚度差异均有统计学意义（〈0.05）。 结论：髋臼横形骨折采用接骨板后方入路内固定时,锁定重建接骨板固定的稳定性优于重建接骨板,而且距骨折线最近的两侧螺孔给予螺钉固定能增强内固定的稳定性。     

胫骨远端骨折应用交锁髓内钉固定时远端不同锁定钉状态的有限元分析

目的 探究胫骨远端骨折应用交锁髓内钉固定时远端不同锁定钉状态的稳定性及其生物力学特性。方法 选择一名健康成年男性的胫骨CT Dicom数据,应用mimics、geomagic和solidworks软件构建胫骨、髓内钉、锁定钉的3D模型,然后按照髓内钉远端不同锁定状态分为试验组（两枚横向锁定钉和一枚纵向锁定钉）和对照组（两枚横向锁定钉）,分别给予轴向、侧向和扭转方向的不同大小的载荷,以模拟正常人体胫骨和内固定系统在不同受力情况下的应力和位移分布情况。结果 试验组和对照组的应力分布没有明显差异,二者都集中在骨-螺钉结合部位,但试验组在轴向、侧向和扭转方向的不同大小的载荷下的最大等效应力均略低于对照组,在轴向300、600、900 N载荷下,试验组的最大等效应力为24.84、49.68、74.52 MPa,对照组的为27.80、55.51、83.27 MPa;在扭转2、4、6 N/m的载荷下,试验组的最大等效应力为144.87、290.92、431.80 MPa,对照组为146.01、292.03、434.80 MPa;在侧向300、600、900 N载荷下,试验组的最大等效应力为209.79、419.58、629.37 MPa,对照组为210.47、420.94、631.41 MPa。在形变位移方面,两组的内固定系统都没有发生明显形变,且试验组的最大位移均略小于对照组。在轴向300、600、900 N载荷下,试验组的最大位移为0.022 9、0.045 8、0.068 7 mm,对照组的为0.024 1、0.048 1、0.072 3 mm;在扭转2、4、6 N/m的载荷下,试验组的最大位移为0.217 8、0.428 8、0.597 8 mm,对照组为0.218 5、0.436 9、0.607 2 mm;在侧向300、600、900 N载荷下,试验组的最大位移为0.949 2、1.898 5、2.847 7 mm,对照组为0.952 5、1.905 0、2.857 6 mm。结论 通过应力和位移对比分析,在使用髓内钉固定胫骨远端骨折时,髓内钉远端固定两枚横向锁定钉已经提供了足够的稳定性,与使用三枚锁定钉相比,两枚锁定钉能减少额外的手术时间和不必要的辐射暴露。在实际情况中还需要手术医生结合临床的具体情况为病人选择最合适的手术方案。     

掌侧锁定钢板联合背侧植骨治疗C3型桡骨远端骨折的疗效观察

目的 观察掌侧锁定钢板联合背侧植骨治疗C3型桡骨远端骨折的疗效。方法 回顾性分析我院2016年1月至2017年12月收治的采用掌侧锁定钢板内固定联合背侧入路植骨的19例桡骨远端AO C3型骨折病人,术后测量桡骨远端掌倾角、尺偏角及桡骨高度,采用Gartland和Werley评分系统评估腕关节功能。结果 所有病人均获得1年以上随访,Gartland和Werley腕关节功能评分显示：优10例,良7例,可2例。末次随访掌倾角为9.48°±1.84°、尺偏角为14.68°±0.82°及桡骨远端高度为（12.45±0.32） mm,与术前比较,差异均有统计学意义（P均＜0.05）。未出现伤口感染、肌腱激惹、肌腱断裂及创伤性关节炎等并发症。结论 掌侧锁定钢板联合背侧植骨治疗桡骨远端AO C3型骨折简单、可靠且有效。     

三枚交叉桥架埋头钉与锁定接骨板固定Mason Ⅲ型桡骨头骨折稳定性的有限元分析

目的:利用有限元方法比较3枚交叉桥架埋头钉和锁定接骨板(锁定钢板)固定MasonⅢ型桡骨头骨折的生物力学稳定性。方法:利用逆向建模技术,将1例25岁健康男性青年桡骨CT数据及内固定数据导入相关软件,分别建立MasonⅢ型桡骨头骨折的3枚交叉桥架构型埋头钉与锁定钢板的三维有限元模型,对桡骨头进行100 N轴向加载,比较两组模型最大位移、内固定上最大Von Mises 应力及应力分布等指标。结果:3枚交叉桥架埋头钉组和锁定钢板组最大位移分别为0.069 mm和0.087 mm,内固定上Von Mises 应力峰值分别为18.59 MPa和31.85 MPa,3枚交叉桥架埋头钉组应力分布更加均匀。结论:两种内固定方式均能提供良好的固定强度,3枚交叉桥架埋头钉较锁定钢板固定方式更具稳定性,应力分布更均匀。     

骨折端加压螺钉结合锁定钢板固定老年股骨远段简单骨折的生物力学分析

目的 比较单纯钉板系统（单纯法）与骨折端加压螺钉结合锁定钢板（联合法）固定老年股骨远段简单骨折的生物力学强度。方法 建立AO/OTA-33 A1型老年股骨远段骨折模型,分别用102 mm工作长度单纯法（A组）和联合法（B组）、82 mm工作长度单纯法（C组）和联合法（D组）固定。施加700 N轴向和4 N·m扭转载荷,比较锁定钢板的应力分布及峰值、位移分布及峰值、骨折端剪切位移、骨折端轴向位移。结果 (1)锁定钢板的应力分布及峰值情况：使用骨折端加压螺钉后,应力峰值从骨折线区域的股骨干侧方钢板转移到骨折线区域的拉力螺钉,而锁定钢板上的应力峰值明显降低。(2)锁定钢板的位移分布及峰值情况：使用骨折端加压螺钉后,锁定钢板上的位移峰值明显降低,联合法模型组的位移均小于单纯法模型组。(3)骨折端剪切位移情况：联合法模型组均小于单纯法模型组。上述3项指标,700 N轴向载荷下,82 mm工作长度模型下降幅度均更大;4 N·m扭转载荷下,102 mm工作长度模型下降幅度均更大。(4)骨折端轴向位移情况：扭转载荷下可忽略不计;轴向载荷下联合法模型组均小于单纯法模型组,82 mm工作长度模型下降幅度更...     

内翻型弓形股骨对膝骨性关节炎下肢力线的影响

目的 探讨股骨弓形形态与股骨远端关节线方向的相关性。方法 纳入2018年至2019年因膝骨性关节炎在我院行初次全膝关节置换的病例共126例（187膝）,其中男39例（47膝）,女87例（140膝）,年龄为（68.1±3.7）岁（61~79岁）。术前均拍摄下肢全长片。收集术前胫股机械轴内侧角（HKA）、股骨弓形角（FBA）、股骨下段外翻角（dAMA）、股骨远端关节线外侧机械角（mLDFA）、胫骨近端关节线内侧机械角（mMPTA）以及胫股关节线夹角（JLCA）,依据FBA大小分为显著弓形组（FBA＞4°）、轻度弓形组（4°≥FBA＞2°）、非弓形组（2°≥FBA≥0°）。比较上述形态学参数的组间差异,并分析显著弓形组内各参数相关性。结果 显著弓形组内股骨弓形、股骨下段外翻、股骨侧关节线内翻以及膝内翻最显著（FBA=5.1°±0.6°,dAMA=7.0°±1.6°,mLDFA=94.5°±1.0°,HKA=171.4°±4.3°,P＜0.001）;而非弓形组内胫骨侧关节线内翻和胫股关节面内翻最显著（mMPTA=86.7°±1.6°,P＜0.05;JLCA=-4.4°±2.5°,P＜0.001）。显著弓形组内FBA与mLDFA存在较强相关性（r=0.607,P＜0.01）。结论 弓形股骨与膝骨性关节炎的股骨关节线内翻显著相关,并使下肢整体内翻增加。     

内踝解剖型钩钢板治疗粉碎性内踝骨折的疗效分析

目的 评价内踝解剖型钩钢板治疗粉碎性内踝骨折的临床疗效。方法 对2015年3月至2017年6月采用内踝解剖型钩钢板治疗粉碎性内踝骨折的30例病人进行回顾性分析,其中男18例,女12例;年龄为21~50岁,平均34.5岁。受伤原因：扭伤10例,直接暴力骨折20例。左踝12例,右踝18例。30例病人均行切开复位内固定手术,内踝应用解剖型钩钢板固定,合并外踝及后踝骨折的病人,外踝应用解剖钢板固定,后踝应用空心螺钉或钢板固定。采用美国足踝外科医师协会（American Orthopedic Foot and Ankle Society, AOFAS）踝与后足功能评分系统、踝关节活动度和疼痛视觉模拟评分量表（visual analogue scale, VAS）评价术前及末次随访时病人的踝关节功能。结果 所有30例病人的随访时间为6~18个月,平均13.1个月。术后切口均一期甲级愈合,无感染、皮瓣坏死、骨折移位、内固定松动、骨不愈合等并发症出现。手术前后的AOFAS踝-后足评分分别为（12.0±10.0）分、（90.0±3.1）分,VAS评分分别为（5.4±1.0）分、（1.3±0.3）分,差异均有统计学意义（P均＜0.05）。末次随访时平均踝关节活动度为60.2°±6.2°。结论 采用内踝解剖型钩钢板治疗粉碎性内踝骨折,固定牢固,操作方便,病人术后功能恢复好,是治疗粉碎性内踝骨折有效的固定方法。     

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.