下颈椎经椎弓根螺钉内固定相关解剖学观察

目的为下颈椎经椎弓根螺钉内固定提供应用解剖学基础及形态学资料。方法应用游标卡尺和量角器对24具成人颈椎干燥标本C3~7椎弓根的高度、宽度、骨性椎管长度、轴线长度、内外侧皮质厚度及轴线夹角进行解剖学测量,并分别计算各节段左右侧椎弓根测量值的均值和标准差,进行统计学分析。结果C3~7椎弓根的椎弓根最窄处截面上下皮质骨高度(PH)和松质骨高度(PSH)分别为4.21mm和7.64mm,宽度分别为3.64mm和5.88mm;轴线长度、骨性椎管长度及侧块部长度分别为15.75mm、32.20mm及8.12mm;最狭窄处内、外侧皮质厚度为0.68mm和1.65mm;椎弓根轴线与矢状线在水平面上的夹角C3:47.12°±3.05°、C4:43.47°±1.49°、C5:40.15±2.58°、C6:38.55°±2.45°、C7:35.16°±2.10°;椎弓根轴线与水平面间夹角C3:8.50°±2.50°、C4:4.83°±1.65°、C5:1.25°±1.45°、C6:-(4.50°±2.50°)、C7:-(8.50°±2.50°)。结论本实验实体测量数据与国内外数据无显著差异,但发现颈椎椎弓根解剖形态个体变异程度较大,术前必须对置钉椎体进行CT、X线片检查,确定适合个体的进钉点、进钉方向、螺钉直径及长度等。颈椎椎弓根螺钉技术仍然是一种相对安全、固定可靠的手术方法。     

手持式颈椎椎弓根螺钉置钉瞄准器的研制及意义

目的:研制能三维调节角度的手持式置钉瞄准器,为颈椎椎弓根螺钉置钉提供帮助。方法:制作以杠杆百分表显示偏摆角度的瞄准器,利用图形矢量化软件快速处理术前轴位CT图和45°斜位X线片,精确确定进钉点、置入角度、螺钉直径与长度,推导出椎弓根术前影像学数据与瞄准器钻套调整角的关系公式,采用正弦规校验瞄准器钻套调整角。以瞄准器为钻模在9具新鲜成人标本颈椎椎弓根上进行钻孔,并进行个体化置钉。结果:共置入椎弓根螺钉46枚,42枚位置正确,正确率为91%。结论:手持式颈椎椎弓根螺钉置钉瞄准器可提高置钉的准确性和安全性,有临床应用前景。     

颈椎椎弓根螺钉徒手植入技术临床研究

目的：评价颈椎椎弓根螺钉徒手植入技术(无须术中影像技术引导)的安全性和可靠性。方法：作者应用Axis内固定系统(美国枢法模公司)对36例颈椎疾病患者进行颈后路经椎弓根内固定术,共植入螺钉144枚。椎弓根螺钉植入要点为：①术前仔细观察颈椎的侧位和双斜位x线片,并予以CT扫描以评估螺钉进针点、进针方向以及螺钉的长度及直径：②术中清晰地显露颈椎侧块和突间关节,用直径3．0mm高速球形磨钻去除侧块外卜象限处骨皮质,然后用2.0mm的自制手锥沿椎弓根事先确定的方向轻轻钻入,若遇阻力则需略改变方向,使其自然置入,深约2．0cm～2．5cm。确定无误后,则安置Axis钛板和置入长度合适的椎弓根螺钉;③安装完毕后,即用C掣臂作双斜位透视,无误后关闭切口。结果：从C3到C7,共植入根弓根螺钉144枚,其中10枚(6．8％)钉初次置入后感觉松动,经校正后二次置入成功,11枚(3．5％)钉道钻孔后出血较多,但及时处理后出血停止并无不良结果。术后X线斜位片及CT片显示,16枚(11．1％)螺钉穿破椎弓根,其中10枚(6．9％)螺钉穿破椎弓根外侧皮质,4枚(2,8％)钉穿破椎弓根上侧皮质,2枚(1．3％)钉穿破椎弓根卜侧皮质。随访未发现与螺钉置入穿破椎弓根皮质仃关的神经血管损伤问题。结论：本研究提示,在事先充分的埘每个患者颈椎椎弓根X线及CT解剖结构了解的情况下,徒手置入椎弓根螺钉行颈椎后路内同定是安全查行。     

颈椎斜位X线片在颈椎椎弓根钉固定中应用的研究

目的：探讨通过颈椎斜位X线片观察椎弓根的位置和方向,及其在判断椎弓根钉固定中准确,安全地进行钉的作用。方法：人尸体颈椎30例,其中椎动脉造影8例,椎动脉脊髓同时造影6例,根据术前X线斜位片,结合解剖标记定位,选择是钉点及进行钉方向,将直径3．5mm、长度24mm的不锈钢螺钉固定于C2或C3－C6或C7椎弓根中,共160枚,通过术后斜位X线片中判断螺钉在椎弓根的位置,并与CT扫描结果对照,以肯定X线的判断,结果：螺钉位置方向正确者152枚,X线片与CT扫描片的判断完全相符;X线判断螺钉偏向椎弓根外侧边缘5枚,偏向椎弓根内侧的边缘3枚。CT扫描确位于椎弓根外侧边缘3枚,怀疑进入椎动脉孔的2枚;在椎弓根内侧边缘没有进入椎管的3枚。结论：术前通过X线斜位片基本可以解椎弓根方向,上下径;通过术后X线斜位片可较为准确地判断椎弓根钉在椎弓根内的位置及有无进行推动脉孔、椎管的情况,X线与CT的结果差异可能与CT扫描的角度及其伪影有关,该方法简单易行。     

应用C形臂X线机评价颈椎椎弓根螺钉位置：螺钉同轴位及斜位摄片

与腰椎和胸椎相比，颈椎椎弓根螺钉还未得到广泛应用，原因主要为颈椎椎弓根较小，置入螺钉的风险较大。到目前为止，还没有关于术中评价颈椎椎弓根螺钉位置的研究。为研究传统C形臂X线机摄片判断颈椎椎弓根螺钉不良位置的敏感性及特异性，本文作者采用C形臂X线机对已放置颈椎椎弓根螺钉的人类尸体脊柱行斜位及螺钉同轴位摄片，借此来评价螺钉的位置，[第一段]     

颈椎前路椎弓根螺钉置入的解剖学研究

[目的]分析颈椎前路椎弓根螺钉内固定的解剖学参数,研究其可行性;通过文献分析比较国内外相关数据。[方法]取42具成人正常干燥颈椎标本,分别用手工和三维CT测量C2^C7椎弓根高度和宽度,进钉点位置,进钉方向,前路椎弓根螺钉进钉轴线上的椎体长度、椎弓根长度及总长度,用统计学分析手工和CT测量差异。以"颈椎"、"前路"、"椎弓根"为关键词搜索CNKI、PubMed、Scopus,纳入含以上相关数据的文献进行比较分析。[结果]手工测量数据与CT数据无统计学差异。除6.4%的C3椎弓根宽度<4 mm外,C2C7椎弓根高度和宽度,进钉点位置,进钉方向,前路椎弓根螺钉进钉轴线上的椎体长度、椎弓根长度及总长度,用统计学分析手工和CT测量差异。以"颈椎"、"前路"、"椎弓根"为关键词搜索CNKI、PubMed、Scopus,纳入含以上相关数据的文献进行比较分析。[结果]手工测量数据与CT数据无统计学差异。除6.4%的C3椎弓根宽度<4 mm外,C2^C7椎体椎弓根平均高度和宽度均≥4 mm。进钉点位置:C3、C4位于椎体正中矢状面的对侧,距离正中为2C7椎体椎弓根平均高度和宽度均≥4 mm。进钉点位置:C3、C4位于椎体正中矢状面的对侧,距离正中为2³ mm;C53 mm;C5^C7位于同侧,距离正中C5:1.38 mm,C6、C7:4C7位于同侧,距离正中C5:1.38 mm,C6、C7:4⁵ mm。C35 mm。C3^C7距离椎体上终板的距离为5C7距离椎体上终板的距离为5⁸ mm。进钉点方向,与矢状面的夹角:C2、C5、C6为38°8 mm。进钉点方向,与矢状面的夹角:C2、C5、C6为38°⁴0°,C3、C4为43°40°,C3、C4为43°⁴7°;与横断面的夹角:C247°;与横断面的夹角:C2^C4角度为下倾,角度分别为19.43°,10.58°和5.93°;C5C4角度为下倾,角度分别为19.43°,10.58°和5.93°;C5^C7角度为头倾,分别为1.94°,6.29°和7.50°。各椎弓根轴线总长度为29C7角度为头倾,分别为1.94°,6.29°和7.50°。各椎弓根轴线总长度为29³2 mm,轴线上椎体长度约为14 mm。比较国内外文献中椎弓根宽度和高度以及进钉点位置显示:上述解剖学数据存在差异。[结论]该实验利用手工和三维CT进行大样本研究,为临床上应用颈椎前路椎弓根螺钉内固定提供了解剖学数据。同时针对国内外不同测量方法和测量对象得出的数据进行对比,为进一步研究其差异提供依据。     

下颈椎椎弓根螺钉置钉技巧探讨

[目的]探讨下颈椎椎弓根螺钉的置钉技巧和手术体会。[方法]2004年7月~2006年4月,在前期尸体标本操作的基础上,C型臂引导下采用下颈椎椎弓根螺钉技术治疗颈椎疾患15例。常规后路,术中显露侧块至其外侧缘,辨清上关节突关节面基底部上缘;选择侧块外缘内5 mm,上关节突关节面基底部下方3 mm处为进钉点,球磨去皮质。2 mm手钻开路并探子确认,保持与上终板平行并40°~45°内倾角。不攻丝置入3.5 mm皮质骨螺钉。[结果]除1枚C4螺钉未能成功外,共计置入C3~7下颈椎椎弓根螺钉86枚,平均螺钉长度(26±1.6)mm,CT下各钉内倾角度平均值37.9°±5.4°。术中2枚(2.9%)在开路时发生钉道活动性出血。术后CT示椎弓根壁损伤6枚(8.8%)。术后无神经血管损伤并发症。[结论]颈椎椎弓根螺钉技术相对安全,置钉成功的关键是手感。     

下颈椎经关节突关节椎弓根螺钉固定的可行性

目的:探讨下颈椎后路经关节突关节椎弓根螺钉固定的可行性和技术参数,为临床应用提供参考。方法:取20具颈椎标本,仔细解剖颈部的后侧和前侧方,清楚显露颈椎侧块和椎弓根。以侧块外下象限的中心点为进钉点,从C3/4～C6/7直视下经关节突关节置入椎弓根螺钉,通过CT重建,测量经关节突关节椎弓根螺钉内固定进钉角度和钉道长度。结果:经关节突关节椎弓根螺钉均成功置入,螺钉固定方向在矢状面呈尾倾,冠状面呈内倾,理想角度为在矢状面尾倾50.3°±4.9°,在冠状面内倾42.8°±4.0°。螺钉钉道长度为(34.1±1.4)mm,各固定节段间略有不同,但差异无统计学意义(P>0.05)。结论:下颈椎后路经关节突关节椎弓根螺钉固定是可行的,但置钉时要求较高的准确性,可以作为颈椎侧块螺钉和椎弓根螺钉固定的一种补充方法。     

颈椎弓根螺钉内固定的解剖学研究

目的探讨颈椎弓根螺钉内固定的定位定向方法。方法设计椎体平面固定架,用游标卡尺、角度计和标本涂钡X线片对40具成人颈椎干燥标本进行解剖学观测。内容包括:椎弓根高度、宽度、轴线长度、轴线角度,上下关节突间侧凹的深度及存在率,椎弓根上下切迹、关节面、椎弓后上缘与椎体上平面的垂直高度及关节突后平面角度。结果C2~C7上下关节突间侧凹的存在率为100%。颈椎弓根完全可以接受直径3.5mm、长28mm的螺钉内固定;椎弓根在椎体平面上的外展角C1为20°,C2上为25°、下为44°,C3~C5为45°~47°,C6、C7为40°。除寰枢椎外,颈椎弓根后结构、关节突间侧凹对应椎弓根轴线。椎弓根的指向与关节突后平面角度密切相关:椎弓后上缘高度线、关节突后平面和椎体上平面三者之间形成前后两个180°互补角,前角大于90°时椎弓根指向前下方,小于90°时指向上终板。关节突后平面的平均角度C3 为-2.30°±1.82°,C4为2.32°±1.98°,C5为2.42°±1.87°,C6为2.36°±1.56°,C7为15.22°±2.68°。进钉点在C1为后弓缘与上关节突后突尖中垂线的交点,C2为上椎弓根外缘矢状线与下关节突上缘水平线交点,C3~C7为垂直于关节突后平面的椎弓后上缘水平线与关节突间侧凹外缘的矢状线交点。结论关节突间侧凹、侧块后平面及椎弓后上缘,三者     

下颈椎椎弓根内固定的解剖学研究与临床应用

目的：为椎弓根螺钉在颈椎的应用提供解剖学基础，介绍手术方法和适应证。方法：用游标卡尺和Ｘ线摄片测量方法，对５４具成人颈椎干燥标本Ｃ３～Ｃ７椎弓根的高度、宽度、长度、进钉点定位及椎弓根轴线的角度等进行解剖学观测。结果：颈椎椎弓根可以接受螺钉内固定；进钉点定位在Ｃ３～Ｃ６位于关节突背面外上象限的中点，Ｃ７位于关节突中垂线接近上关节面的下缘；进钉方向平行于椎体的上终板，与矢状线的夹角在Ｃ３～Ｃ６为４０°～４５°，Ｃ７为３０°～４０°。应用椎弓根螺钉钢板治疗颈椎损伤、肿瘤１９例，无颈髓、神经根及椎动脉损伤等并发症。１８例获随访，平均随访１３个月，固定节段稳定，神经功能有不同程度恢复，临床疗效满意。结论：颈椎椎弓根内固定，固定坚强，手术后可以摆脱外固定，方便护理，利于病人早期锻炼和康复，是一种良好的重建颈椎稳定的内固定方法。     

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.     

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.