前路经寰枢关节锁定钛板螺钉内固定系统三维稳定性的实验研究

[目的]评价前路经寰枢关节锁定钛板螺钉内固定系统治疗寰枢椎不稳的三维稳定性。[方法]8例颈椎新鲜标本,对每一标本分别测定完整状态、齿状突Ⅱ型骨折、前路经寰枢关节锁定钛板螺钉内固定和后路椎弓根螺钉内固定的三维运动范围,并对结果进行统计学分析。[结果]前路固定的前屈为(1.39±0.26)°,后伸为(1.40±0.22)°,侧屈为(1.43±0.23)°,旋转为(1.77±0.34)°。后路固定的前屈为(1.37±0.23)°,后伸为(1.39±0.20)°,侧屈为(1.41±0.22)°,旋转为(1.77±0.33)°,前路经寰枢关节锁定钛板螺钉固定和后路椎弓根螺钉固定的寰枢椎三维运动范围无显著统计学差异(前屈P=0.930,后伸P=0.952,左右侧屈P=0.947,左右旋转P=0.950)。[结论]前路经寰枢关节锁定钛板螺钉固定术的三维稳定性与后路椎弓根螺钉固定术相当,为寰枢椎不稳患者提供了一种手术治疗选择。     

经口咽前路寰枢椎复位钢板的生物力学评价

目的　对经口咽前路寰枢椎复位钢板 (TransoralpharyngealAtlantoaxialReductionPlate ,TARP)。进行生物力学评价。 方法　 6例寰枢椎新鲜标本 ,在脊柱三维运动试验机上将四种常用的寰枢前后路融合术与我们自行设计的经口咽前路寰枢椎复位钢板进行对比 ,分 7组 :①对照组 (完整标本 ) ;②损伤组 ;③前路寰枢椎复位钢板组 ;④后路Brooks钢丝组 ;⑤Magerl +Brooks组 ;⑥Magerl组 ;⑦前路经枢椎体寰椎侧块螺钉组 (ATS)。分别测量其三维运动范围 (ROM)。 结果　TARP和Magerl+Brooks在各个方向上均无显著性差异 ,ROM值略大于后者 ,除在侧屈时和旋转与Magerl无显著差异外 ,二者抗屈伸、侧屈和旋转均强于其它内固定方法。Magerl除在侧屈和旋转范围与Brooks、前路经枢椎体寰椎侧块螺钉的旋转范围无显著差异外 ,与Brooks和前路经枢椎体寰椎侧块螺钉在其它运动有显著差异 ,ROM值小于Brooks和前路经枢椎体寰椎侧块螺钉。Brooks和前路经枢椎体寰椎侧块螺钉在各向上均无显著差异。结论　TARP与Magerl+Brooks较其它三种临床上常用的前后路寰枢融合手术固定更牢靠 ,TARP具有良好的生物力学性能。联合后路Magerl+Brooks较单用后路Magerl更牢固。前路经枢椎体寰椎侧块螺钉固定与Brooks钢丝效果相当     

经口咽前路寰枢椎复位钢板的生物力学评价

目的 对经口咽前路寰枢椎复位钢板(Transoralpharyngeal Atlantoaxial Reduction Plate，TARP)。进行生物力学评价。方法 6例寰枢椎新鲜标本，在脊柱三维运动试验机上将四种常用的寰枢前后路融合术与我们自行设计的经口咽前路寰枢椎复位钢板进行对比，分7组：①对照组(完整标本)；②损伤组；③前路寰枢椎复位钢板组；④后路Brooks钢丝组；⑤Magerl Brooks组；⑥Magerl组；⑦前路经枢椎体寰椎侧块螺钉组(ATS)。分别测量其三维运动范围(ROM)。结果 TARP和Magerl Brooks在各个方向上均无显著性差异，ROM值略大于后者，除在侧屈时和旋转与Magerl无显著差异外，二者抗屈伸、侧屈和旋转均强于其它内固定方法。Magerl除在侧屈和旋转范围与Brooks、前路经枢椎体寰椎侧块螺钉的旋转范围无显著差异外，与Brooks和前路经枢椎体寰椎侧块螺钉在其它运动有显著差异，ROM值小于Brooks和前路经枢椎体寰椎侧块螺钉。Brooks和前路经枢椎体寰椎侧块螺钉在各向上均无显著差异。结论 TARP与Magerl Brooks较其它三种临床上常用的前后路寰枢融合手术固定更牢靠，TARP具有良好的生物力学性能。联合后路Magerl Brooks较单用后路Magerl更牢固。前路经枢椎体寰椎侧块螺钉固定与Brooks钢丝效果相当。     

上颈椎不稳前路内固定方式的选择

目的:探讨上颈椎不稳前路内固定手术方式的选择及治疗效果。方法:自2000年3月至2010年9月,采用寰枢椎前路内固定手术治疗上颈椎不稳83例,男59例,女24例;年龄20～68岁,平均42岁。其中齿状突螺钉内固定36例,寰枢椎前路经关节螺钉内固定16例,C2,3前路钢板内固定23例,齿状突螺钉联合寰枢椎经关节螺钉内固定5例,齿状突螺钉联合C2,3钢板内固定2例,寰枢椎经关节螺钉联合C2,3钢板内固定1例。结果:1例颈脊髓完全损伤患者,行寰枢椎经关节螺钉内固定,术后1个月死于肺部感染。其余病例获得随访,时间8个月～3年,平均15个月。无椎动脉及脊髓损伤,所有病例寰枢椎获得稳定。36例齿状突螺钉内固定及5例齿状突联合寰枢椎经关节螺钉内固定者,未植骨,齿状突骨性愈合。寰枢椎经关节螺钉内固定病例:1例并发肺部感染死亡;1例齿状突ⅡC型粉碎性骨折并寰枢关节前脱位,齿状突及植骨未骨性愈合,但寰枢关节纤维连接无不稳定表现;1例寰枢椎陈旧性前脱位Ⅰ期前路寰枢椎经关节螺钉内固定,Ⅱ期后路Brooks钢丝内固定后路植骨,寰枢椎骨性融合。其他病例均植骨并获骨性融合。结论:上颈椎不稳患者,根据不同的骨折及不稳类型,选择相应的前路内固定,可取得较好疗效。     

后路椎弓根钉板系统治疗寰枢关节脱位的临床效果

寰枢关节脱位是上颈椎不稳类疾病中最为常见的一种。治疗寰枢关节脱位常采用后路寰枢椎短节段固定融合术,包括Gallie、Brooks钢丝、椎板夹及寰枢椎侧块关节螺钉等。这些术式虽保留了寰枕关节和颈椎其他节段的功能,但容易发生内固定断裂、松动及植骨不融合等并发症。生物力学研究表明寰枢椎椎弓根螺钉内固定系统较其他后路固定技术具有更好的生物力学稳定性和矫形能力。     

新型寰枢椎固定组合的生物力学测试

[目的]采用尸体标本测试枢椎椎板螺钉联合新型寰椎椎板钩内固定系统的生物力学稳定性。[方法]采用6具新鲜尸体颈椎标本(C_(0～3)),分别测试完整标本模型(完整组)、寰枢椎不稳标本模型(失稳组)、双侧寰枢椎经关节螺钉联合Gallie固定植骨模型(bTFS+G组)、双侧寰枢椎经关节螺钉联合新型寰椎椎板钩固定植骨模型(bTFS+H组)、一侧寰枢椎经关节螺钉与对侧枢椎椎板螺钉联合新型寰椎椎板钩非对称固定植骨模型(非对称组),在1.5 Nm载荷下,C_(1/2)节段的前后屈伸、左右侧(P0.05)。三种内固定组中:bTFS+G固定组在前后屈伸和左右侧屈方向上具有最小的ROM,bTFS+H内固定组在轴向旋转运动方向上有最小的ROM。非对称内固定组ROM在前后屈伸、左右侧屈、轴向旋转方向上均较另外两组大,但差异均无统计学意义(P0.05)。[结论]寰枢椎经关节螺钉与对侧枢椎椎板螺钉联合新型寰椎椎板钩非对称固定植骨可提供良好的生物力学稳定性。     

骨科——脊柱

经后路寰椎椎弓根螺钉系统内固定融合术治疗颈椎疾患；双侧寰椎椎板挂钩及寰枢椎关节间隙螺钉固定术治疗创伤性寰枢椎不稳；两种下颈椎经关节固定技术的静力学比较；前路单枚空心螺钉内固定术治疗齿状突骨折12例临床报道;椎动脉损伤后颈椎前路减压的疗效评价;前后路联合减压植骨带锁钢板内固定治疗复杂颈椎损伤的分析;[编者按]     

寰枢椎后路内固定技术的研究进展

寰枢椎不稳多采用后路手术治疗,但由于其解剖及生物力学上的特殊性,内固定方式也与下颈椎明显不同,目的是提供即刻稳定性,解除脊髓及神经压迫,促进融合。目前固定方式主要包括钢丝固定技术、椎板夹或椎板钩技术、Magerl技术、寰椎侧块螺钉技术及椎弓根钉技术、枢椎椎弓根钉、枢椎椎板螺钉、峡部螺钉等,其后又出现寰椎后弓螺钉、后弓锁定钛板、寰枢侧块关节间融合器等新技术,但各固定方式在技术及恢复上颈椎稳定性上存在优缺点,故熟悉各内固定技术并对该领域研究进展有所了解有极其重要的意义。     

骨科：脊柱

经前路颈椎多节段椎管扩大术的实验研究；颈椎后路经关节螺钉钢板内固定术在下颈椎骨折脱位中的应用；后-前路联合手术治疗下颈椎骨折脱位伴关节突交锁；椎弓根螺钉技术在下颈椎不稳中的安全使用方法；经口咽Ⅱ型前路寰枢椎复位钢板内固定系统在难复性寰枢椎脱位中的应用     

前路经寰枢外侧关节螺钉内固定术的生物力学评价

目的：评价不同方法前路经寰枢外侧关节螺钉内固定的稳定性和刚度。方法：通过体外生物力学实验，对15例新鲜尸体标本的正常、齿状突切除、三种不同有路经寰枢外侧关节螺钉内固定术、后路Brooks法寰枢关节内固定术等状态进行三维角度运动范围和关节刚度进行测试。结果：前路经寰枢外侧关节螺钉内固定术明显减少寰枢关节的各向角度运动范围；三种不同方法之间寰枢关节的各向角度运动范围和刚度无明显差异；前路经寰枢外侧关节螺钉内固定术较后路Brooks法内固定术，寰枢关节的旋转和侧屈运动范围减少更明显，寰枢关节的由前向后剪切和旋转刚度更高。结论：前路经寰枢外侧关节螺钉内固定术的稳定性和刚度达到了临床治疗的要求，术后对外固定强度的依赖较低，三种不同方法的生物力学结果相近，为简化操作和设计提供了新思路。     

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.     

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.     

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.     

Dilemma of Membrane Biocompatibility and Reuse

Abstract: Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation. leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.     

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.