脊柱胸腰段骨折侧前方TSRH与Z-plate固定的生物力学研究

目的：比较前路TSRH与Z-plate不同固定方法在脊柱内固定后强度、刚度和稳定性等力学性能的改变。方法：采用15具尸体胸腰段标本，5具为正常(NS)对照组，10具造成压缩性骨折后分两组(每组5具)，分别用TSRH和Z-plate行侧前方固定，应用实验应力分析法进行生物力学测试。结果：应用TSRH内固定的脊柱应变、位移比正常脊柱对照组的应变、位移分别减小17％～20％和8％；周定后的强度和刚度与Z-plate固定组相比仅小5％和5％，统计显示两种固定方法无显著性差异(P＞0．05)，结论采用TSRH侧前方内固定后的脊柱不但强度、刚度和稳定性得到满足，而且在承载能力、脊柱的稳定性上优于正常对照组，与Z-plate固定组相比无显著性差异，且操作简便，价格也低。     

脊柱胸腰段骨折侧前方TSRH与Z-plate固定的生物力学研究

目的:比较前路TSRH与Z-plate不同固定方法在脊柱内固定后强度、刚度和稳定性等力学性能的改变.方法:采用15具尸体胸腰段标本,5具为正常(NS)对照组,10具造成压缩性骨折后分两组(每组5具),分别用TSRH和Z-plate行侧前方固定,应用实验应力分析法进行生物力学测试.结果:应用TSRH内固定的脊柱应变、位移比正常脊柱对照组的应变、位移分别减小17%～20%和8%;固定后的强度和刚度与Z-plate固定组相比仅小5%和5%,统计显示两种固定方法无显著性差异(P＞0.05).结论采用TSRH侧前方内固定后的脊柱不但强度、刚度和稳定性得到满足,而且在承载能力、脊柱的稳定性上优于正常对照组,与Z-plate固定组相比无显著性差异,且操作简便,价格也低.     

滑动椎弓根钉系统稳定性体外生物力学测试

[目的]对滑动椎弓根钉系统(SPSS)与通用椎弓根钉系统(USS)在脊柱侧凸固定强度、刚度和稳定性等方面进行生物力学比较,以测试滑动椎弓根螺钉内固定系统稳定性的生物力学性能.[方法]采用12具猪新鲜脊柱标本,随机分成两组分别测量不同工况下T12椎体的位移,并计算其强度和刚度进行比较.[结果]滑动组和通用组无论在轴向压缩、前屈、后伸、侧屈情况下,主应变、位移变化及固定强度、刚度均无显著性差异(P>0.05).[结论]滑动椎弓根钉系统治疗脊柱侧凸同样能够达到通用椎弓根钉系统相同的矫形效果及生物力学稳定性,同时它不影响青少年生长发育.     

三种胸腰椎前路内固定器的生物力学评价

目的对三种胸腰椎前路内固定器进行生物力学评价.方法采用新鲜成人胸腰椎标本(T12～S1)15具,制成前、中柱损伤模型,分别以DunnⅢ、NTP、Z-plate固定,进行强度、刚度和稳定性的研究.结果胸腰椎骨折采用三种前路内固定器固定后,在脊柱的强度、刚度和稳定性方面,NTP、Z-plate均优于DunnⅢ(P＜0.05),而NTP和Z-plate无显著性差别(P＞0.05).结论NTP和Z-plate系统符合脊柱的生物力学,能有效恢复失稳脊柱的稳定性,是较为理想的前路内固定器.     

齿轮撑开式脊柱复位固定板装置的研制及生物力学评价

[目的] 研制一种新型的齿轮撑开式脊柱复位固定板装置(GDP),进行生物力学测试并评价其生物力学性能.[方法] 采用医用钛合金制成GDP植入物,用不锈钢制成专用工具.18具新鲜小牛腰椎标本随机分为3组,对GDP组内固定进行载荷-应变、载荷-位移、强度、刚度、扭转强度及极限承载能力测试,并与对照组(CD、Steffee)对比分析.[结果] 齿轮撑开式脊柱复位固定板(GDP)组在载荷-应变、载荷-位移、强度、刚度、扭转强度及极限承载能力方面均优于对照组,统计学分析有显著性差异(P<0.05).[结论] GDP具有良好的生物力学稳定性,对促进骨折愈合、防止后突畸形复发和椎体高度丢失具有重要意义.     

三种胸腰椎前路内固定器的生物力学评价

目的:对三种胸腰椎前路内固定器进行生物力学评价.方法:采用新鲜成人胸腰椎标本(T12～S1)15具,制成前、中柱损伤模型,分别以DunnⅢ、NTP、Z-plate固定,进行强度、刚度和稳定性的研究.结果:胸腰椎骨折采用三种前路内固定器固定后,在脊柱的强度、刚度和稳定性方面,NTP、Z-plate均优于DunnⅢ(P＜0.05),而NTP和Z-plate无显著性差别(P＞0.05).结论:NTP和Z-plate系统符合脊柱的生物力学,能有效恢复失稳脊柱的稳定性,是较为理想的前路内固定器.     

King Ⅲ型特发性脊柱侧凸经胸侧前方椎体三维矫形术

[目的]探讨King Ⅲ型特发性脊柱侧凸经胸侧前方椎体三维矫形术的治疗效果。[方法]回顾本院2003年9月-2005年9月应用TSRH、CDH-M。等矫形器械对12例青少年King Ⅲ型特发性脊柱侧凸患者经凸侧胸腔于椎体侧前方行椎间松解、椎体三维矫形、植骨融合内固定术的临床资料，分析评价其手术并发症、侧凸矫正率及随访结果。[结果]术后出现肺部并发症2例，1例肺不张，1例呼吸道梗阻。经气管插管和呼吸机辅助呼吸后缓解。所有病例均未出现大血管损伤、脊髓损伤、肺炎和乳糜胸等并发症。术前胸椎Cobb’s角48^o～66^o，平均52．6^o。术后胸椎残余Cobb，s角平均15.2^o，矫正率77．8％。随访12～36个月，平均18．5个月。12例患者均获得了较好的节段性骨融合，矫正率无明显丢失，未发现假关节、内固定松动或断裂、失代偿等并发症。[结论]经胸椎体侧前方二维矫形手术是治疗King Ⅲ型特发性脊柱侧凸畸形的一种较安全、有效的内固定方式。     

椎体侧前方减压植骨融合钢板内固定术治疗胸腰椎爆裂骨折

目的 评价经胸腰椎侧前方手术入路Z-plate内固定系统固定结合椎间植骨融合手术治疗胸腰椎爆裂骨折的临床疗效.方法 采用经胸腰椎侧前方手术入路,椎管减压椎间植骨融合,Z-plate内固定系统固定治疗胸腰椎爆裂骨折168例.结果 本组获12～24个月的随访,平均18个月,椎间植骨融合率为100％,术后神经症状恢复率为90％;168例术后各项指标均较术前有显著改善,差异有统计学意义(P＜0.05);随访期间内固定无松动、断裂等.结论 经胸、腰椎侧前方手术入路Z-plate内固定系统固定结合椎间植骨融合手术治疗胸腰椎爆裂骨折,有效恢复了脊柱的前、中柱的稳定性,彻底清除了来自椎体前方的致压物对椎管内脊髓或马尾神经的压迫,是治疗胸腰椎爆裂骨折的理想方法之一.     

腰椎前路可调式一体化钢板融合器的研制及生物力学测试

目的:研制腰椎前路可调式一体化钢板融合器(ALCP),并对其进行生物力学测试。方法:根据国人腰椎结构特点设计,应用医用钛合金材料制成ALCP。取15具6月龄猪腰椎标本,随机分成3组,每组5具,一组不行任何处理(对照组);两组行L3/4、L4/5椎间盘切除,并在L4椎体上开槽,一组用ALCP固定(ALCP组),另一组用前路钢板人工椎体固定(AVB组),测量每组标本在受到轴向压缩、前屈、后伸、侧屈及扭转状态下的载荷-位移、载荷-应变关系及强度和刚度的变化。结果:三组在轴向压缩、前屈、后伸和侧屈时腰椎的应变随载荷增大而增大,相同载荷下三组间应变无显著性差异(P0.05);在500N以内载荷作用下,腰椎纵向压缩位移随载荷的增加而增加,三组间位移无显著性差异(P0.05)。500N载荷轴向压缩时,ALCP组的应力强度最大(P0.05),而在前屈、后伸及侧屈时三组间应力强度无统计学差异(P0.05);三组间轴向刚度和弯曲刚度均无显著性差异(P0.05)。ALCP组的最大扭矩为4.12N·m,AVB组为3.87N·m,对照组为4.18N·m,三组间无显著性差异(P0.05)。ALCP组的扭转刚度与AVB组和对照组比较亦无显著性显差异(P0.05)。结论:腰椎经ALCP固定后的生物力学性能接近人工椎体加前路钢板固定和正常腰椎。     

单节段后路内固定对于胸腰段单椎体压缩骨折的生物力学分析

[目的]对于单节段后路钉棒系统内固定器治疗胸腰段单椎体压缩骨折进行生物力学测试,为此种手术方法在临床上的应用提供生物力学支持.[方法]取36具冰冻家猪胸腰段椎体标本,采用Panjabi法制作预损伤模型,分为3组,每组12个样本,分别为单节段固定组,跨阶段固定组以及失稳组.分别对每组进行椎体强度、载荷-应变、稳定性与刚度、扭转强度、位移的生物力学测试.[结果]经过生物力学测试,椎体强度:单节段内固定组与跨节段内固定组相比,A点应力减少7.2％,B点应力减少16.8％ (P ＜0.05).单节段组与失稳组相比,A点应力减少13.9％,B点应力减少26.7％ (P ＜0.05).载荷-应变:单节段内固定组小于跨节段内固定组和失稳组,A点应力分别减少6.9％、13.8％.B点应力分别减少15.3％、30％ (P ＜0.05).水平位移:单节段内固定组比跨节段固定组和失稳组分别减少6.8％和40％ (P ＜0.05).纵向位移:单节段内固定组比跨节段固定组和失稳组分别减少13％和37％ (P ＜0.05).[结论]单节段后路内固定在生物力学上予以支持,临床可以应用.     

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.     

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.     

The analgesic effect of racemic ketamine in patients with chronic ischemic pain due to lower extremity arteriosclerosis obliterans

Background : Ketamine in sub-dissociative doses has been shown to have analgesic and phantom-Limb pain, where conventional treatment has often failed. Chronic ischemic pain due to lower extremity arteriosclerosis obliterans often responds poorly to analgesics, and the pain-generating mechanisms are not well understood.
Methods : Eight patients with rest pain in the lower extremity due to arteriosclerosis obliterans were given sub-dissociative doses of 0.15, 0.30, or 0.45 mg/kg racemic ketamine and morphine 10 mg as a 5-min infusion on four separate days in a cross-over, double-blind, randomised protocol. Plasma levels of (S)- and (R)-ketamine and their nor-metabolites were analysed with an enantioselective high-performance liquid chromatography (HPLC) method. Pain levels were evaluated with a visual analogue scale (VAS).
Results : Individual pain levels were highly variable during and after all the infusions but the pooled pain levels showed a dose-dependent analgesic effect of ketamine with a transient but complete pain relief in all patients at the highest dose (0.45 mg/ kg). Side-effects, mainly disturbed cognition and perception, were pronounced and dose-dependent. Morphine 10 mg had an analgesic peak at 20 min and 5/8 patients had complete pain relief. The remaining 3 patients also had high baseline pain scores, indicating a higher analgesic potency for the 0.30 and 0.45 mg/ kg ketamine doses than for morphine 10 mg.
Conclusion : We have demonstrated a potent dose-dependent analgesic effect of racemic ketamine in clinical ischemic pain. Due to a narrow therapeutic window, this analgesic effect is probably best utilised in combination with other analgesics.     

Intravenous endotoxin does not increase tissue extravasation of albumin in rats

Background : It is unclear whether activation of the inducible nitric oxide synthase (iNOS) increases or decreases the extravasation of plasma.
Methods : Chloralose anaesthetised male Wistar rats received E. coli lipopolysacharide (LPS), 3 mg kg^-1 i.v., or the corresponding volume of saline, 3 or 5 h before the end of the experiment. Mean arterial pressure (MAP) and heart rate (HR) were recorded. Tissue clearance of radio-labelled albumin, during the last 2 h of each experiment, was determined by a double-isotope method. In separate animals, the serum concentration of nitrite and nitrate was determined, 5 h after LPS or the solvent.
Main Results : LPS initially decreased MAP and lastingly increased HR. In the 3-h LPS animals (n=8), tissue plasma clearance was lower in the heart and calf muscle and increased only in diaphragm, compared to corresponding control animals (n=8). In the 5-h LPS rats, clearance was lowered (n=8) in the entire gastrointestinal tract and in testes, compared to controls (n=8). The serum nitrite/nitrate concentration was higher in animals given LPS (n=6) than in controls (n=6).
Conclusion : After LPS, tissue clearance of albumin was not increased in any major tissue, in spite of increased serum levels of NO end products. Apparently, after activation of iNOS, the augmented release of NO is not necessarily associated with increased albumin extravasation.     

Adrenaline markedly improves thoracic epidural analgesia produced by a low-dose infusion of bupivacaine, fentanyl and adrenaline after major surgery: A randomised, double-blind, cross-over study with and without adrenaline

Background: Basic pharmacological research indicates that there are synergistic antinociceptive effects at the spinal cord level between adrenaline, fentanyl and bupivacaine. Our clinical experience with such a mixture in a thoracic epidural infusion after major surgery confirms this. The objectives of the present study were to evaluate the effects on postoperative pain intensity, pain relief and side effects when removing adrenaline from this triple epidural mixture. Methods: A prospective, randomised, double-blind, cross-over study was carried out in 24 patients after major thoracic or abdominal surgery. Patients with only mild pain when coughing during a titrated thoracic epidural infusion of about 10 ml · h^?1 of bupivacaine 1 mg · ml^?1, fentanyl 2 μg · ml^?1, and adrenaline 2 μg · ml^?1 were included. On the 1^st and 2^nd postoperative days each patient was given a double-blind epidural infusion, at the same rate, with or without adrenaline. The effect was observed for 4 h or until pain when coughing became unacceptable in spite of a rescue analgesic procedure. Rescue analgesia consisted of up to two epidural bolus injections per hour and i.v. morphine if necessary. All patients received rectal paracetamol 1 g, every 8 h. Fentanyl serum concentrations were measured with a radioimmunoassay technique at the start and end of each study period. Main outcome measures were extent of sensory blockade and pain intensity at rest and when coughing, evaluated by a visual analogue scale, a verbal categorical rating scale, the Prince Henry Hospital pain score, and an overall quality of pain relief score. Results: The number of hypaesthetic dermatomal segments decreased (P <0.001) and pain intensity at rest and when coughing increased (P <0.001) when adrenaline was omitted from the triple epidural mixture. This change started within the first hour after removing adrenaline. After 3 h pain intensity when coughing had increased to unacceptable levels in spite of rescue analgesia (epidural bolus injections and i.v. morphine). Within 15–20 min after restarting the triple epidural mixture with adrenaline, pain intensity was again reduced to mild pain when coughing. Serum concentration of fentanyl doubled from 0.22 to 0.45 ng · ml^?1 (P <0.01), and there was more sedation during the period without adrenaline. Conclusions: Adrenaline increases sensory block and improves the pain-relieving effect of a mixture of bupivacaine and fentanyl infused epidurally at a thoracic level after major thoracic or abdominal surgery. Serum fentanyl concentrations doubled and sedation increased when adrenaline was removed from the epidural infusion, indicating more rapid vascular absorption and systemic effects of fentanyl.     

Reduction of Plasma Fibrinogen, Immunoglobulin G, and Immunoglobulin M Concentrations by Immunoadsorption Therapy with Tryptophan and Phenylalanine Adsorbents

Abstract Immunoadsorption (1A) therapy with tryptophan (TR-350) or phenylalanine (PH-350) adsorbents has been used to reduce the concentration of serum antibodies in human lymphocyte antigen (HLA)-immunized patients. Other forms of plasma purification have been reported to reduce the level of fibrinogen, which affects the blood properties. In this study we investigated the effects of IA therapy using both adsorbents on plasma fibrinogen and immunoglobulins G and M in 13 patients (8 patients were treated with TR-350, and 5 patients were treated with PH-350). During each session 1 plasma volume (2.8 ± 0.4 L of plasma) was processed through the immunocolumn and then returned to the patient together with the blood cells. Compared with the pretreatment values, the plasma fibrinogen, IgG, and IgM concentrations were significantly reduced after IA therapy (p < 0.01 for TR-350; p < 0.04 for PH-350). There was a positive correlation between the degree of reduction of plasma proteins and the number of IA treatments given. A nonpara-metric test (Wilcoxon's signed-rank test or the Mann-Whitney test) was used for statistical analysis. We conclude from our study that IA therapy effectively lowers the plasma levels of fibrinogen, IgG, and IgM and thus can be considered a valuable alternative to other blood purification methods.     

Utilisation des médicaments prokinétiques en réanimation : indications et limites ?

Enteral feeding is often limited by gastric and intestinal motility disturbances in critically ill patients, particularly in patients with shock. So, promotility agents are frequently used to improve tolerance to enteral nutrition. This review summaries the pathophysiology, presents the available pharmacological strategies, the clinical data, the counter-indications and the principal limits. The clinical data are poor. No study demonstrates a positive effect on clinical outcomes. Metoclopramide and erythromycin seems to be the more effective. Considering the risk of antibiotic resistance, the first line use of erythromycin should be avoided in favor of metoclopramide.     

Anesthésie générale chez l’enfant : quid des pratiques en 2010 ?

Introduction

The practice of pediatric anesthesia requires a regular update of scientific knowledge and technical skills. To provide the most adequate Continuing Medical Education programs, it is necessary to assess the practices of pediatric anesthesiologists. Thus, the objective of this survey was to draw a picture of the current clinical practices of general anesthesia in children, in France.

Material and methods

One thousand one hundred and fifty questionnaires were given to anesthesiologists involved in pediatric cases. These questionnaires collected information on various aspects of clinical practice relative to induction, maintenance, recovery from general anaesthesia and also classical debated points such as children with Upper Respiratory Infection (URI), emergence agitation, epileptoid signs or anaesthetic management of adenoidectomy. Differences in practices between CHG (general hospital), CHU (teaching hospital), LIBERAL (private) and PSPH (semi-private) hospitals were investigated.

Results

There were 1025 questionnaires completed. Fifty-five percent of responders worked in public hospitals (CHG and CHU); 77% had a practice that was 25% or less of pediatric cases. In children from 3 to 10 years: 72% of respondents used always premedication and two thirds performed inhalation induction in more than 50% of cases. For induction, 53% used sevoflurane (SEVO) at 7 or 8%. Respondents from LIBERAL used higher SEVO concentrations. Tracheal intubation was performed with SEVO alone (37%), SEVO and propofol (55%) and SEVO with myorelaxant (8%), 93% of respondents used a bolus of opioid. For maintenance, the majority of respondents used SEVO associated with sufentanil; desflurane and remifentanil were more frequently used in CHU. Two thirds of respondents used N₂O. Depth of anesthesia was commonly assessed by hemodynamic changes (52%), end tidal concentration of halogenated (38%) or automated devices based on EEG (7%). In children with URI, 98% of respondents used SEVO for anesthesia. To control the airway 42% used a tracheal tube, 30% a laryngeal mask and 20% a facial mask. Emergence agitation was an important concern for two thirds of respondents, while epileptoid signs were considered as important by only 20%. Eighty-nine percent of respondents practiced anesthesia for adenoidectomy. Anesthesia was induced by inhalation of SEVO 7–8% (41%), 6% (39%) or 4% (12%), 66% put an intravenous line (less frequently in LIBERAL). 67% of the responders managed adenoidectomy without any device to control the airway (more frequently in LIBERAL), 32% administrated a bolus of opioid (less frequently in LIBERAL).

Discussion

This survey demonstrated that the practices regarding general anesthesia in children are relatively homogenous. Most of the differences appeared between LIBERAL and the others structures; the anaesthetic management for adenoidectomy illustrates these findings.     

Intérêt d’une rééducation précoce pour les patients neurologiques

Rehabilitation improves the functional prognosis of patients after a neurologic lesion, and tendency is to begin rehabilitation as soon as possible. This review focuses on the interest and the feasibility of very early rehabilitation, initiated from critical care units. It is necessary to precisely assess patients’ impairments and disabilities in order to define rehabilitation objectives. Valid and simple tools must support this evaluation. Rehabilitation will be directed to preventing decubitus complications and active rehabilitation. The sooner rehabilitation is started; the better functional prognosis seems to be.