犬肢体爆炸伤并海水浸泡后致感染的组织病理变化研究

目的 观察犬肢体爆炸伤并海水浸泡后早期伤口感染情况及其病理特征.方法 选择体质量10～15 kg成年犬40只,随机分为实验组和对照组,每组20只.分别将左后肢爆炸致伤,以生理盐水冲洗、无菌敷料覆盖,实验组20只伤肢以海水浸泡1h,对照组20只未行海水浸泡.术后3d取伤口组织行病理检查、细菌培养及药敏实验,术后统计各犬肢体伤口愈合时间;4、8周取组织病理切片观察.结果 实验组与对照组2种处理方式相比较,实验组15只(75％)感染,对照组8只(40％)感染,差异有统计学意义(P＜0.05);实验组伤口平均愈合时间为38.4d,对照组为23.1 d,差异有统计学意义(P＜0.05).实验组内弧菌属感染后组织坏死及炎性改变较杆菌属及球菌属更严重,4、8周实验组组织坏死及炎性改变较对照组严重.结论 行海水浸泡后感染组织坏死及炎性程度较未行海水浸泡要严重;且行海水浸泡后,伤口的愈合时间长.     

爆震伤合并大段骨缺损及海水浸泡外科治疗的实验研究

[目的]探讨爆震伤合并大段骨缺损及海水浸泡的外科治疗方式并研究其成骨效果。[方法]以24只成年狗为实验对象,随机等量分为实验组与对照组,实验组对左后肢采用爆震致伤,截取狗后肢胫骨中段,形成2cm长的骨缺损,以海水浸泡伤肢1 h,经彻底清创后骨折端间植入医用纳米羟基磷灰石人工骨,骨折远近端以外固定架固定,对照组左后肢爆震致伤后,以同样方法造成2 cm长骨缺损,以海水浸泡伤肢1 h,彻底清创后不植入人工骨,同样以外固定架固定,两组均常规行预防感染治疗,术后4、8、12周分别摄X线片、组织切片、电镜检查及X射线能谱分析,观察成骨情况。[结果]实验组术后第4周可见新生编织骨;第8周可见大量巢状软骨细胞团及骨岛;第12周新生骨组织呈数个连续过渡的条带样分布区。随植入时间延长,植入体中钙/磷比值趋向于自体皮质骨。对照组骨折端钝圆,骨髓腔封闭,呈骨不愈合状态。[结论]应用外固定架和纳米羟基磷灰石人工骨植入可以有效治疗爆震伤合并大段骨缺损及海水浸泡的病例。     

大段仿生活性人工骨修复犬长骨缺损的实验研究

[目的]观察大段活性人工骨对大动物骨缺损的修复效果,了解材料的降解性。[方法]以快速成形技术制备犬用PLLA.cTCP大段人工骨载体材料,按3 mg/块材料的标准复合rhBMP-2制备犬用大段活性人工骨。以犬桡骨2.0 cm骨缺损为实验模型,将大段活性人工骨(实验组)和单纯载体材料(对照组)植入骨缺损,通过影像学、组织学、生物力学检查评价骨缺损的修复效果,通过图像分析仪分析材料的降解情况。[结果]影像学检查表明,实验组术后12周骨痂与断端完全连接,术后24周骨痂塑形良好。对照组术后24周无骨痂生长,缺损未修复。组织学检查证明,实验组术后12周骨痂外层形成板层骨,中央形成小梁骨及骨髓组织,材料部分吸收;术后24周,骨痂板层骨致密,小梁骨减少,骨髓组织增多,材料进一步降解。对照组术后12周纤维组织将材料包裹并长入其中,材料部分降解;术后24周材料被纤维组织分割包裹,材料进一步降解。术后12周实验组和对照组的降解率分别为43.2%和35.7%,术后24周58.4%和45.4%。生物力学检测证明,术后24周实验组桡骨的抗弯强度超过正常骨的强度。[结论]PLLA.cTCP大段活性人工骨对大动物骨缺损有良好的修复效果,材料的降解性还需要改善。     

大段感染骨煮沸后异位再血管化的实验研究

[目的]探讨大段感染骨经煮沸后异位再血管化的可行性。[方法]将120只健康6个月龄中国白兔随机分为实验组、对照组各60只。实验组:首先制备兔胫骨感染模型,然后截取2.0 cm长感染胫骨,经煮沸灭菌后,异位于对侧大腿股直肌与股内侧肌间隙之隐动脉处,1.0克氏针固定于股骨上。对照组:在同一部位截取相同长度的无菌胫骨段经生理盐水浸泡处理后,余步骤同实验组。两组分别于术后0、4、6、8、10、12周各处死10只兔子,通过大体标本观察及免疫组织化学染色法检测异位血管化骨CD34阳性血管数和血管内皮生长因子(vascular endothelial growth factor,VEGF)蛋白表达量的灰度值,分析判断两组血管化情况。[结果]术后4、6、8周,实验组CD34阳性血管数均低于对照组(P0.05),其VEGF蛋白表达量也均低于对照组,但仅术后8周差异有统计学意义(P0.05);术后10、12周,实验组CD34及VEGF检测结果均稍高于对照组,但差异均无统计学意义(P0.05)。实验组和对照组CD34阳性血管数及VEGF蛋白表达量分别在术后10、8周达到峰值,之后均成下降趋势。此时,两组异位血管化骨几乎完全被软组织包裹;两者贴附紧密,分离困难。[结论]自体正常骨在术后8周完成再血管化,要快于煮沸骨,而煮沸骨在术后10周也完成再血管化。证实兔大段感染胫骨经煮沸灭菌后异位于肌肉丰富的知名血管处,使其再血管化,转化为血管化骨是可行的。     

海水浸泡开放性骨折伤愈合过程中组织病理学和血管内皮细胞生长因子(VEGF)表达

目的通过观察普通开放骨折、海水浸泡开放骨折愈合过程的组织学变化和骨痂中血管内皮细胞生长因子(VEGF)的表达,了解海水浸泡开放性骨折愈合过程VEGF的作用与机制。方法新西兰大白兔59只,随机分为普通开放骨折组(对照组)24只和海水浸泡开放骨折组(实验组)35只。造成桡骨横行1.5mm缺损完全开放骨折,普通开放骨折伤组旷置3h,海水浸泡开放骨折伤组海水浸泡伤口3h,之后依次缝合伤口。于第1、3、7、14、21、28、45天处死动物。观察海水浸泡开放骨折伤在骨折愈合中不同时间的病理过程。采用RT-PCR方法检测普通开放骨折、海水浸泡开放骨折不同阶段骨痂中的VEGF的表达及变化。结果海水浸泡开放骨折伤骨痂形成延迟,骨折后第28天,对照组断端间骨痂为骨性骨痂者8例,为软骨者4例,实验组断端间骨痂为骨性骨痂者6例,为软骨者14例。海水浸泡骨折伤愈合过程中新生骨痂的VEGF表达在骨折后逐渐升高,术后14d达到高峰,之后逐渐下降,但在28d时仍保持较高水平,与一般开放骨折愈合过程的VEGF表达无显著差异(P>0.05)。结论海水浸泡使骨折骨痂形成不良率增高,骨折愈合过程有延迟倾向;但骨折愈合过程中VEGF表达无明显变化。     

比较钢板与桥接组合式内固定系统对犬胫骨骨折愈合的影响

[目的]对比钢板和桥接组合式内固定系统对骨折愈合的影响。[方法]选取20条家犬,分为4、8、12、16周亚组,建立双侧胫骨骨折模型,分别以桥接组合式内固定系统(实验组)和钢板(对照组)进行固定,术后4、8、12、16周分别处死动物,通过不同时段的大体标本、X线片、光镜观察研究骨折愈合情况。[方法]术后对照组分别出现骨折劈裂、钢板松脱和钢板断裂各1例,而实验组仅内固定变形弯曲1例;X线片显示实验组骨痂生长早于对照组,各时期评分实验组均高于对照组,16周时有显著统计学意义(P<0.05);光镜观察显示,实验组纤维母细胞、新生毛细血管及骨痂的生长均早于对照组,各时期评分均高于对照组,8、16周时有显著统计学意义(P<0.05)。[结论]与钢板相比,桥接组合式内固定系统有利于骨折稳定和骨折端血管长入,可促进骨折愈合。     

骨膜促进骨-肌腱结点愈合的研究

[目的]探讨骨膜对骨-肌腱结合部位愈合的影响,通过实验证明骨膜促进骨-肌腱结合部位细胞增生,进而促进该部位愈合.[方法]48只18周龄新西兰大白兔随机分为2组,实验组将骨膜游离并植入兔髌骨部分切除模型中骨-肌腱结点中,对照组只进行手术,不植入骨膜.在术后4、8、12周处死动物取标本进行大体和组织学观察.[结果]大体观察可见实验组骨-肌腱结合部位愈合较早.组织学检查显示实验组术后4、8周骨-肌腱结合部组织愈合明显,以从松质骨再生和骨-肌腱愈合接点纤维软骨带的再生为特征,较对照组迅速,提示早期实验组恢复较对照组迅速.[结论]骨膜可以促进骨-肌腱结合部位细胞增生,增加细胞基质合成,促进新生骨和纤维软骨移行带形成,促进其愈合.     

海水浸泡股骨开放性骨折的早期救治

目的利用犬动物模型研究海水浸泡股骨开放性骨折的伤情特点及早期救治方法。方法20只华北成年犬,随机分为对照与海水浸泡两组。于股骨中段截骨制备开放性骨折的动物模型,实验组犬浸泡于海水中3h,对照组于笼内放置3h,两组均于3h后行伤口清创、钢板螺钉内固定术。结果①对照组和海水浸泡组分别有1只和3只动物伤口感染(P>0.05);②病理结果显示海水浸泡组软骨骨痂较多;③生物力学测试两组骨愈合刚度分别为(451.49±183.00)N和(150.15±20.16)N(P<0.05);④影像学观察两组骨痂形成及骨愈合无明显差别。结论①海水浸泡使开放骨折感染率有增高趋势。②海水浸泡使骨折愈合质量下降,骨折愈合过程有延迟倾向。③生物力学测定示海水浸泡开放骨折愈合强度明显低于对照组。④内固定有增加伤口感染的风险,但在股骨这一特定部位可选择性应用。     

海水浸泡开放性骨折不同救治方法的实验研究

目的观察两种骨折固定方法救治海水浸泡开放性骨折的大体形态、组织病理学、影像学变化。方法取成年新西兰兔50只，随机分为三组：对照组10只、A组20只、B组20只。于胫骨中段截骨制成开放性骨折动物模型。对照组伤口自然旷置3h，A组和B组海水浸泡伤口3h。随后对照组和A组行伤口清创、钢板螺钉内固定术；B组行伤口清创、外固定架固定、伤口开放换药、二期缝合。观察各组的伤口感染情况、骨折愈合的组织学、影像学变化和测定骨折断端骨痂的平均比灰度值。结果a）对照组感染1只（10％），A组感染15只（75％），B组感染5只（25％）。各组间结果有统计学差异（P〈0．05）。b）术岳45d时各组间骨折断端组织愈合等级有统计学差异（P〈0．05）。c）术后45d时各组间骨折部位骨痂的生长情况在影像学上表现为对照组大于B组大于A组。各组间骨愈合率对照组为100％，A组为66．7％，B组为93．3％。d）术后45d时骨折断端间骨痂的平均比灰度值对照组为8．1149±1．2043，A组为6．2268±1．4000，B组为6．5138±1．3045，各组间有统计学差异（P〈0．05）。结论海水浸泡使开放性骨折伤口感染率增高；海水浸泡使开放性骨折断端骨痂形成不良率增高；骨外固定架与钢板内固定比较救治成功率提高。     

骨科金属置入物并发感染的动物模型构建方法及效果评价

[目的]构建一种基于钛合金置人物的兔胫骨金黄色葡萄球菌感染模型,并探讨不同菌液浓度在模型制备中的作用.[方法]48只新西兰大白兔随机分成5组,4个实验组每组10只,对照组8只.在胫骨结节内侧钻孔后,向各实验组动物胫骨髓腔内注入浓度分别为1.0 ×105、1.0×106、1.0×107、1.0×108 CFU/ml的ATCC25923金黄色葡萄球菌悬液.然后在髓腔内置入长4.0 cm,直径0.25 cm钛合金棒.对照组注入等量生理盐水后置入相同规格的钛合金棒.术后4周通过肢体外观、体温测量、影像检查、微生物学检测和组织学分析,评价感染模型建立情况,筛选最佳细菌浓度.[结果]术后动物患肢早期局部软组织肿胀,出现跛行,体温呈现2周内明显升高、之后逐渐下降的趋势.术后4周实验组动物放射学显示不同程度骨膜反应,皮质溶解,死骨形成及软组织肿胀等表现.细菌培养结果显示注入的细菌浓度越高,感染越严重,其中C、D组感染率均为100％,高于A、B组;D组死亡率最高.4周组织切片出现骨髓纤维化、坏死骨片等感染表现.[结论]适当浓度的金黄色葡萄球菌菌液髓腔注射联合钛合金棒置入可以构建稳定的兔长骨感染模型,此为骨科金属置人物并发感染的防治研究奠定了基础.     

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.     

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.     

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.     

The multiply injured child

Blunt trauma is the principal cause of childhood death in many developed countries. This review outlines the differences between adults and children with respect to resuscitation and treatment of orthopaedic injuries in a child with polytrauma. Recent advances in techniques of fracture stabilization are reported.     

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.     

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.