复合血管生成素1基因及富血小板血浆的组织工程骨修复桡骨骨缺损

目的探讨以β磷酸三钙(β tricalcium phosphate,β-TCP)为支架,复合富血小板血浆(platelet-rich plasma,PRP)和转染血管生成素1(angiopoietin1,Ang-1)基因的组织工程骨修复节段性骨缺损的能力。方法取兔股骨骨髓分离培养BMSCs,将Ang-1基因通过慢病毒转染至第2代BMSCs,转染后48h接种于β-TCP上培养,然后复合0.5mLPRP,制备复合PRP的组织工程骨。取20只3月龄新西兰大白兔制备双侧桡骨15mm骨缺损模型,采用自身对照,分别于每只动物左侧和右侧骨缺损处植入未转染Ang-1基因的组织工程骨(对照组)及转染Ang-1基因的组织工程骨(实验组)。术后行大体观察,于2、4、8、12周行X线片观察,取材行HE染色、免疫组织化学染色及生物力学检测。结果细胞转染48h后转染效率>90%,通过RT-PCR检测到转染细胞内Ang-1基因表达显著增高。术后所有动物患肢活动良好。X线片观察示实验组术后4周骨缺损处已有骨痂形成,8周有部分骨性愈合,12周骨缺损处完全骨性愈合;对照组至术后12周时无骨性愈合。HE染色示实验组术后8周有毛细血管出现,12周大量毛细血管生长于新生骨中;对照组8周未见新生毛细血管,12周见少量毛细血管。术后8、12周实验组微血管密度分别为(50.1±7.8)个/mm2和(66.1±3.5)个/mm2,对照组分别为0和(30.3±7.2)个/mm2;术后12周两组间比较差异有统计学意义(Z=—2.107,P=0.031)。免疫组织化学染色观察示术后8周实验组仍有Ang-1分泌。生物力学测试结果显示术后12周实验组三点弯曲试验和压缩试验的最大负荷均显著高于对照组(P<0.05)。结论复合PRP和转染Ang-1基因的组织工程骨修复兔桡骨节段性骨缺损后,组织工程骨内可形成新生血管,促进骨愈合。     

复合富血小板血浆(PRP)的可注射型组织工程骨的构建及其修复兔桡骨缺损的放射学评估

目的用自体富血小板血浆(PRP)、骨髓基质干细胞(BMSCs)和纤维蛋白胶(FG)构建可注射型组织工程骨并从放射学方面评价其修复自体兔桡骨缺损的效果。方法36只新西兰兔随机分为A、B、C三组,每组12只。所有动物术前1周抽取耳背中央动脉血提取PRP。A组于术前1～2个月抽取双髂骨处骨髓并培养出BMSCs,在体外与FG及自体PRP构建成可注型组织工程骨,植入自体桡骨1.5cm节段性骨缺损,为实验组。B、C两组分别植入PRP FG、FG于同样骨缺损处为对照组。另取4只桡骨同样部位和大小骨缺损旷置作为空白组。术后4、8、12周时摄前臂正位X线片。用放射影像学评分和图像分析X线阻射影比较骨缺损的修复情况。结果A、B两组骨缺损放射影像学评分以及新生骨痂的密度在4、8、12周均优于C组(P<0.05),A、B两组之间在放射影像学评分上无明显差别(P>0.05),但在新生骨痂密度上,A>B>C(P<0.05)。空白组术后16周骨缺损无愈合。结论PRP对骨缺损愈合有明显促进作用,复合PRP的可注射型材料与BMSCs构建组织工程骨可修复兔桡骨节段性骨缺损。     

低氧诱导因子-1α诱导分化的骨髓间充质干细胞复合纳米人工骨修复兔桡骨缺损

目的探讨低氧诱导因子-1α（hypoxia?inducible factor?1α, HIF?1α）诱导分化的骨髓间充质干细胞（bone marrow mesenchymal stem cells, BMSCs）复合纳米羟基磷灰石（nano?hydroxyapatite, nano?HA）人工骨修复兔桡骨缺损的效果。方法取兔胫骨的骨髓分离培养并鉴定BMSCs;制备携带HIF?1α的慢病毒表达系统,感染BMSCs后与nano?HA共培养得到HIF?1α?eGFP/BMSCs/nano?HA人工骨材料。将30只2月龄新西兰大白兔随机分为3组,每组10只,均通过手术截骨后制成桡骨骨缺损模型,实验组填充HIF?1α?eGFP/BMSCs/nano?HA人工骨材料,对照组填充BMSCs/nano?HA,空白组不填充任何材料。于术后4、8、12周摄X线片观察骨缺损处,并于术后12周获得兔桡骨的大体标本和病理切片,比较桡骨缺损的愈合情况。结果经鉴定,分离培养得到的BMSCs形态良好,高表达CD90、CD105;所有实验动物的桡骨中段缺损模型均构建成功,通过对实验兔的大体标本、X线片及病理切片进行比较分析,实验组和对照组的骨缺损均有所修复,但实验组的新骨形成量更大,骨缺损修复能力优于对照组,空白组骨缺损区未能得到修复。结论 HIF?1α诱导分化的BMSCs与nano?HA复合制成的HIF?1α?eGFP/BMSCs/nano?HA复合人工骨具有良好的骨缺损修复能力,可能成为一种理想的骨缺损修复材料。     

骨形态发生蛋白2基因转染的骨髓间充质干细胞修复羊胫骨干骨缺损

目的 评价腺病毒介导的人骨形卷发生蛋白2(Adv-hBMP-2）基因转染的羊骨髓间充质干细胞(BMSCs)对长骨干骨缺损的修复效果．方法 22只羊，体重18．1～29．5kg．制造羊胫骨干骨缺损(2．1cm)．分为4组：Ⅰ组．Adv-hBMP-2转染BMSCs组(8只)；Ⅱ组．腺病毒介导的β半乳槠苷酶(Adv-βgal)转染BMSCs组(6只)；Ⅲ组，未转染BMSCs组(6只)；Ⅳ组，未治疗组（2只)。细胞自身分泌的细胞外基质作为细胞载体。分期行X线、计量组织学检查和生物力学测定。结果 X线检查示Ⅰ组的羊胫骨干骨缺损内有明显骨痂形成；24周，Ⅰ、Ⅱ、Ⅲ和Ⅳ组的愈合率分别为6/7、1／5、2／5及0／1，X线疗效评分显示Ⅰ组与Ⅱ、Ⅲ组的评分比较．差异有显著性意义。组织学检查显示，与其它组相比．Ⅰ组的新生骨量最多，并有皮质骨形成。生物力学测试示Ⅰ组的力学强度最大。结论 Adv-hBMP-2基因转染的BMSCs在缺乏骨传导性支架的条件下可修复长骨干骨缺损。     

兔骨髓基质细胞促进血管生成和成骨作用

目的了解骨髓基质细胞(BMSCs)对珊瑚人工骨血管生成和成骨作用的影响。方法从兔的骨髓中分离BMSCs进行体外培养扩增后,载入珊瑚人工骨,植入新西兰白兔桡骨干中段15 mm的骨缺损内,与未植入任何填充材料和仅植入珊瑚人工骨的实验动物相比较,使用放射学、微量CT和组织形态学等方法对骨缺损内新生血管和骨组织进行定量分析。结果未植入填充材料的骨缺损全部形成典型的骨折不愈合表现;植入珊瑚骨后,骨缺损内的新骨形成增加但新生血管无明显改变,术后16周无一例完全愈合;植入BMSCs和珊瑚人工骨复合物的骨缺损内新生血管和骨组织均明显增多,术后16周2/3的骨缺损完全愈合。结论BMSCs可促进血管生成和对人工骨材料的爬行替代作用。     

负载不同浓度骨形态发生蛋白的组织工程骨体内成骨的量效关系

目的以聚乳酸-羟基乙酸[poly-(D,L-lactide-co-glycolide),PLGA]为支架,负载不同浓度的骨形态发生蛋白(bonemorphogeneticprotein,BMP),与骨髓基质干细胞(bonemarrowstemcells,BMSCs)构建成新型的组织工程骨,并观察其体内成骨的量效关系。方法制作新西兰大白兔桡骨中段15mm骨缺损实验模型,植入不同含量BMP的组织工程骨。24只兔随机分为三组:第一组:植入同时负载5.0mgBMP及1×106个已向成骨细胞诱导的BMSCs的组织工程骨(10只);第二组:植入同时负载2.5mgBMP及1×106个已向成骨细胞诱导的BMSCs的组织工程骨(7只);第三组:植入同时负载1.0mgBMP及1×106个已向成骨细胞诱导的BMSCs的组织工程骨(7只)。术后对动物进行大体观察,摄X线片观察各组术后4、8、12周骨缺损修复情况,比较不同时相的骨缺损区X线阻射密度。于术后第4、8、12周取出骨缺损区标本进行大体观察和组织学切片观察,图像分析骨缺损区域骨小梁的生成数量;取第12周标本行生物力学检测。结果X线片显示术后4周三组动物的桡骨缺损区域均有明显骨痂生成;12周时三组的骨缺损完全愈合率分别为7/8、3/5、3/5;各时相局部X线阻射密度值与新生骨小梁百分比计量显示第一组的新生骨痂及骨小梁最多,并可见髓腔再通现象。生物力学检测结果显示第一组的压缩刚度、扭转刚度、三点弯曲断裂载荷均大于其他两组。结论含5.0mgBMP的PLGA支架与BMSCs复合构建的组织工程骨修复兔桡骨15mm骨缺损的效果最佳。     

骨髓基质干细胞联合血管束植入构筑血管化组织工程骨修复兔大段骨缺损

目的 研究兔骨髓基质干细胞(BMSCs)联合动静脉血管束植入异种脱蛋白松质骨(XDCB)构筑血管化组织工程骨修复兔桡骨中远段完全骨膜骨缺损的能力. 方法 从兔髂嵴捕骨髓培养制备兔BMSCs,将第5代BMSCs种植于多孔XDCB,并进行成骨诱导2周制备组织工程骨,手术中分离兔桡动、静脉血管束.动物模型为制备24只兔舣侧桡骨中远段完全骨膜骨缺损1.5 cm共48侧,分4组修复(n=12),A组为空白未治疗组,B组为单纯材料+血管束植入组(XDCB+VB),C组为组织工程骨组(XDCB+BMSCs),D组为组织工程骨+血管束植入组(XDCB+BMSCs+VB),符组交叉配对.分别于术后4、8、12周行X线片、大体解剖、组织切片、生物力学等检查,观察各组骨缺损修复效能及移植物血管化情况.结果 D组骨缺损修复效能(术后12周新骨面积比2.02%±0.16%)及血管化情况(术后12周血管面积比6.89%±0.32%)优于C组(1.50%±0.28%和3.17%±0.19%),而C组又优于B组(1.59%±0.19%和6.52%±0.23%),A组骨缺损未修复,各组结果差异有统计学意义(P<0.05).结论 BMSCs联合动静脉血管束植入构筑的血管化组织工程骨能促进成骨过程和新生骨的血管化,显著提高组织工程骨修复大段骨缺损的能力.     

透明质酸复合BMP-2转染的兔骨髓基质干细胞在裸鼠肌内成骨的实验研究

我们通过动物实验，对高分子量透明质酸(hyaluronic acid，HA)复合腺病毒介导的人骨形态发生蛋白-2基因(Adv-hBMP-2)体外转染兔骨髓基质干细胞(BMSCs)裸鼠肌内成骨与成软骨能力进行了观察。     

兔胎盘来源间充质干细胞修复兔桡骨骨缺损的实验研究

目的 探讨兔胎盘来源间充质干细胞(PMSCs)构建的组织工程化骨修复兔桡骨节段性骨缺损的能力.方法 取24只大耳白兔,于兔双侧桡骨中下段制造1.5cm的节段性骨缺损,左侧骨缺损用PMSCs构建的组织工程化骨桥接(实验组),右侧用骨髓基质干细胞(BMSCs)构建的组织工程化骨桥接(对照组).实验动物双侧于术后2、4、8、...     

HA复合rhBMP-2转染的BMSCs对羊胫骨延长骨愈合的影响

目的 评价HA复合rhBMP-2的腺病毒(adenovirus mediated rhBMP-2,Adv-rhBMP-2)转染的羊BMSCs对骨痂延长骨愈合的影响. 方法 成年山羊19只,雌雄不限,体重15～20 kg.于每只羊髂嵴上穿刺抽取骨髓10 mL,常规传代培养BMSCs.取第3代BMSCs,以感染复数200转染腺病毒.取0.25%胰蛋白酶消化转染后3 d的细胞1×108个,与HA充分混匀制备Adv-rhBMP-2/BMSCs/HA.建立山羊右侧胫骨延长模型,术后立即于截骨部位注射自体细胞复合物.按术后注入物质不同随机分成4组A组为Adv-rhBMP-2/BMSCs/HA组(n=6),B组为Adv-rhBMP-2/BMSCs组(n=5),C组为Adv-β-gal/BMSCs/HA组(n=4),D组为空白组(n=4).术后第7天开始行胫骨延长,速度1 mm/d,共延长4周.术后5、8、12周摄X线片观察骨痂生长情况,12周处死动物,取标本分别行骨密度检测、生物力学测定、组织学观察和骨形态计量学分析. 结果 X线片检查示,术后5、8周A、B组骨痂生成量明显多于C、D组,X线片定量评分A、B组明显高于C、D组,差异均有统计学意义(P＜0.05);12周各组均在骨延长部位形成连续骨痂.骨密度测定术后12周A、B、C、D组延长部位骨矿物质含量分别为(4.175 ±1.921)、(2.600 ±0.638)、(2.425±0.826)和(1.175 ±0.574)g,骨矿物质密度分别为(0.612 ±0.196)、(0.630 ±0.159)、(0.450 ±0.166)和(0.266 ±0.113)g/cm2,A、B组显著高于C、D组(P＜0.05).生物力学测定A、B、C、D组最大载荷分别为(490.20 ±155.08)、(350.59±80.48)、(221.95±68.79)和(150.65±92.29)N,弹性模量为(178.24±105.80)、(105.88 ±27.09)、(81.18±48.67)和(50.35±47.64)Mpa,各指标A组显著高于C、D组(P＜0.05).组织学观察见A组骨延长处大量新生骨组织,骨小梁多为纵行网状排列.骨形态计量分析示A、B、C、D组新骨体积分别为72.35%±5.68%、67.58%±7.42%、49.63%±4.87%和38.87%±2.35%,A组新生骨生成量明显比D组多(P＜0.05). 结论 HA复合rhBMP-2修饰的BMSCs制备的组织工程骨可促进羊胫骨延长骨愈合.     

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.     

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.     

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.     

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.