经皮前路枢椎齿状突螺钉内固定术的并发症分析

目的 :分析经皮前路齿状突螺钉内固定术治疗枢椎齿状突骨折的并发症及相关防治措施。方法 :2006年6月~2013年12月共收治新鲜枢椎齿状突骨折患者122例,其中男79例,女43例,年龄28~73岁(45.6±14.8岁)。根据Anderson-D′Alonzo分型,Ⅱ型88例,浅Ⅲ型34例。均采用经皮颈椎前路枢椎齿状突螺钉内固定术。记录手术时间,术中出血量,螺钉松动及断裂,医源性血管、神经及食管损伤和切口感染等情况。术后及随访时行颈椎正侧位、开口位X线片及CT检查评估螺钉位置和骨折愈合情况,并记录并发症处理措施。结果:皮肤切口长约0.8~1cm,手术时间40.7±12.2min,术中出血量20ml。术中未发生咽后壁、食管、血管和重要神经等邻近组织损伤。共21例患者出现相关并发症,其中3例在置入螺钉过程中产生枢椎前方骨折,1例术中再置入1枚螺钉行双螺钉固定,另2例术后予Halo-Vest架固定治疗后齿状突骨折骨性愈合;1例术后骨折端分离过大,再次行内窥镜下骨折端植骨术而愈合;1例骨折端轻度移位,术后予以支具固定后骨性愈合;9例螺钉钉尾留置过长,但未出现临床症状;1例术后2d出现喉上神经麻痹,经营养神经治疗后恢复正常;1例切口感染,经抗感染治疗后痊愈;2例分别在术后2个月、3个月出现螺钉脱出,均予翻修,1例行前路寰枢关节融合内固定术,另1例行后路寰枢关节融合内固定术;3例纤维连接,齿状突骨折处无移位,内固定无松动,无需佩戴颈围和二次手术。结论:经皮前路齿状突螺钉内固定术是一种方便、安全、微创的手术方式,术后并发症多数经处理后预后良好,整体翻修率低。     

齿状突骨折经皮前路螺钉内固定术的适应证与疗效分析

[目的]探讨齿状骨折经皮前路螺钉内固定术的适应证和临床疗效.[方法]齿状突骨折19例,Ⅱ型骨折16例,Ⅲ型骨折3例.伴寰椎前脱位10例,后脱位4例,无移位5例.有寰枢椎脱位者术前先行颅骨牵引复位,X线片显示复位满意后,行经皮前路螺钉内固定术.[结果]19例患者术中、术后X线片显示齿状突骨折复位满意、稳定.术后平均随访18.5个月,骨性愈合15例,不愈合2例,延迟愈合2例.[结论]经皮前路螺钉内固定治疗齿状突骨折具有微创、内固定牢靠、早期活动等优点,适应证选择是临床疗效的关键.     

后路寰枢椎钉棒固定非融合治疗新鲜Ⅱ型齿状突骨折保留寰枢椎旋转功能的临床初探

目的:介绍寰枢椎后路钉棒固定非融合治疗新鲜Ⅱ型齿状突骨折保留寰枢椎旋转功能的临床初步疗效. 方法:2010年1月～2011年7月收治8例不适合前路齿状突螺钉固定的新鲜Ⅱ型齿状突骨折患者,其中骨折线呈前下后上型者5例,牵引后齿状突骨折复位不佳者3例;男6例,女2例;年龄21～56岁,平均38岁.在气管插管全麻下行一期后路寰枢椎钉棒固定,不进行后路植骨;待术后随访CT复查显示齿状突骨折骨性愈合后,二期后路手术取出内固定,观察寰枢椎旋转功能的恢复情况. 结果:8例患者均成功进行寰枢椎后路钉棒固定,共置入直径3.5mm的寰椎、枢椎螺钉各16枚,其中寰椎采用椎弓根螺钉固定13枚、部分经椎弓根螺钉固定3枚,枢椎采用椎弓根螺钉固定11枚、椎板螺钉固定5枚;术中齿状突骨折复位满意,未发生椎动脉、脊髓损伤一期术后随访12～24个月,平均16个月,末次随访CT复查显示8例患者齿状突骨折均获得骨性愈合,颈椎左、右旋转均约35°～55°,平均约45°. 二期后路钉棒内固定取出术后颈椎旋转功能即刻得到部分恢复,颈椎左、右旋转均约50°～70°,平均约60°;随访6～12个月后颈椎旋转功能基本恢复正常,颈椎左、右旋转均约80°～90°,平均约85°.结论:对不适合前路齿状突螺钉固定的新鲜Ⅱ型齿状突骨折患者,采用一期后路寰枢椎钉棒固定非融合、二期取出内固定的方法可保留寰枢椎的旋转功能.     

非融合固定与齿状突螺钉固定治疗Anderson-D'Alonzo Ⅱ型齿状突骨折的疗效比较

目的比较颈椎后路寰枢椎非融合固定与颈椎前路齿状突螺钉固定治疗齿状突Anderson-D’’Alonzo Ⅱ型骨折的疗效。方法回顾性分析2015年1月至2020年1月河南省漯河市中心医院脊柱科收治的21例Anderson-D’’Alonzo Ⅱ型齿状突骨折患者资料。根据治疗方法不同分为后路组(采用后路寰枢椎非融合固定手术治疗)和前路组(采用前路齿状突螺钉固定)。后路组12例, 男7例, 女5例;年龄(42.2±11.8)岁。前路组9例, 男5例, 女4例;年龄(40.0±9.1)岁。比较两组患者的手术时间、手术出血量、术中透视次数、骨折愈合时间、颈椎总旋转度及颈椎功能障碍指数(NDI)。结果两组患者术前一般资料的比较差异均无统计学意义(P>0.05), 具有可比性。两组患者均成功置入内置物, 术中骨折复位满意, 未发生动静脉血管及脊髓损伤。所有患者术后随访(24.5±11.3)个月。所有患者均成功置入内置物, 术中骨折复位满意, 未发生动静脉血管及脊髓、神经损伤。前路组患者的手术时间[(108.5±15.9)min]、术中出血量[(48.3±12.2)mL]显著少于后路组患者[(1...     

齿状突骨折并寰枢椎脱位的手术治疗

目的评价几种手术方法治疗齿状突骨折合并寰枢椎脱位的临床应用效果。方法回顾性分析了采用手术治疗的24例齿状突骨折合并寰枢椎脱位的病例,其中齿状突Ⅱ型10例,Ⅲ型14例,采用前路齿状突加压螺钉内固定8例;椎板间ATLAS钛缆系统固定或Apofix椎板夹固定、后路寰枢椎融合10例;改良后路Magerl联合Gallie内固定、寰枢椎融合6例。结果术后随访3～30个月,颈椎活动度的保持以齿状突螺钉固定最佳,后路椎板间固定和Magerl联合Gallie内固定病例颈椎旋转度丧失较多;7例出现不完全性四肢瘫患者的术前脊髓功能Frankel分级C级4例、D级3例,术后D级5例、E级2例,无一例发生脊髓损伤加重及术后感染;术后3个月X线片显示所有内置物无松动、脱落及断裂,无复位丢失。结论前路齿状突螺钉技术是治疗齿状突骨折合并寰枢椎脱位的首选,只有在齿状突螺钉禁忌时才考虑采用寰枢椎融合;坚强内固定是后路寰枢椎融合的有力保障,改良Magerl联合Gallie三点内固定具有较好的生物力学性能,是实施后路寰枢椎融合的理想内固定技术。     

齿状突骨折经皮螺钉内固定手术前后CT重建的意义

目的:探讨齿状突骨折经皮螺钉内固定手术前后应用CT重建的意义。方法:16例齿状突骨折患者,术前进行上颈椎CT扫描及图像后处理,观察齿状突骨折的部位、骨折线走向及移位情况,并测量齿状突解剖学数据。均行经皮前路齿状突螺钉内固定术,术后不同时期同样进行CT重建,以观察齿状突骨折复位、螺钉内固定及骨折愈合等。结果:16例齿状突骨折患者中,AndersonⅡ型10例,其中EyselA型3例,B型2例,C型5例;AndersonⅢ型6例。齿状突基底冠状径8.7±1.1mm,矢状径10.9±1.1mm,齿状突骨折远段长度12.3±1.1mm,齿状突后倾角23.3°±1.2°;术后CT重建证实16例患者中,11例复位及螺钉位置良好,2例螺钉位置有偏斜,2例螺纹未完全通过骨折线,1例螺钉穿破齿状突尖部皮质。随访发现15例达到骨性愈合,1例EyselC型骨折经10个月随访仍未见到骨性愈合,继续随访观察中。结论:经皮前路螺钉内固定治疗齿状突骨折术前、术后行CT重建有利于准确评估骨折状况、制定周密手术方案及评价手术效果。     

前后路联合手术治疗齿状突骨折畸形愈合伴难复性寰枢椎脱位

目的:探讨经口前路松解齿状突部分切除与后路复位固定融合治疗齿状突骨折畸形愈合伴难复性寰枢椎脱位的疗效。方法:2008年1月～2011年1月我院共收治7例齿状突骨折畸形愈合致难复性寰枢椎脱位患者,男5例,女2例,年龄21～51岁,平均36.4岁。术前神经功能JOA评分为5～9分,平均7.3±2.1分;脊髓有效空间(space available for the cord,SAC)为4～12mm,平均8.34±3.68mm。均行经口前路松解、齿状突部分切除,一期后路寰枢椎椎弓根螺钉系统进一步提拉复位、固定、融合术,术后观察神经功能改善情况,并行X线、CT、MRI检查观察复位及植骨融合情况。结果:手术时间280～360min,平均310min。术中出血510～930ml,平均670ml。术中无脊髓神经损伤;1例术中置入枢椎椎弓根螺钉时损伤椎动脉,经原钉道拧入螺钉后完成止血,术后随访无椎动脉损伤的临床表现;1例术中置入寰椎椎弓根螺钉时寰椎后弓下壁破裂,未改变钉道,继续沿椎弓根方向置入螺钉,术后随访无寰枢椎的再失稳和移位。所有患者均获得满意复位。随访9～36个月,平均19.6个月。均在术后6个月获得骨性融合,随访期间未发现螺钉松动、移位、断裂,无寰枢椎再移位、失稳现象。末次随访时,JOA评分为11～15分,平均13.1±2.1分,与术前比较有统计学差异(P<0.05),改善率为78.8%～93.5%,平均87.4%;末次随访时的SAC为11～18mm,平均14.78±2.15mm,与术前比较明显增大(P<0.05)。结论:对于齿状突骨折畸形愈合伴难复性寰枢椎脱位患者,经口咽前路松解齿状突部分切除与后路复位固定融合术可获得好的复位效果,近期疗效满意。     

颈前路中空加压螺钉治疗齿状突骨折

目的 介绍前路中空螺钉内固定治疗Ⅱ型齿状突骨折的方法.方法 对9例Ⅱ型齿状突骨折的患者,在C臂机透视下,采用枢法模UCSS中空加压螺钉固定齿状突.结果 术后复查X线片及CT提示,所有患者内固定位置良好,手术时间55～120 min,术中出血约30ml,随访5～20 月,所有患者骨性愈合,无神经系统并发症,无螺钉松动及咽部异物感,颈椎旋转及屈伸、侧屈功能基本正常.结论 前路中空螺钉内固定治疗Ⅱ型齿状突骨折,创伤小,固定牢固,同时最大限度保留了寰枢椎关节的生理功能.     

骨科机器人辅助齿状突螺钉内固定术9例报告

目的探讨骨科机器人辅助技术在颈前路齿状突螺钉内固定手术中的安全性。方法 2017年11月～2018年8月对9例Ⅱ型齿状突骨折全麻下行齿状突骨折复位,术中三维CT扫描,齿状突螺钉路径规划,骨科机器人引导齿状突螺钉导针植入,齿状突空心螺钉固定。结果平均手术时间178. 3 min(120～240 min),平均术中估计出血量36. 7 ml(20～50ml),术后平均住院时间4. 3 d(3～5 d)。共置入齿状突螺钉10枚,根据Neo评级量表,10枚螺钉均为0级。所有患者均未发生围手术期并发症。术后3个月随访,所有患者骨折愈合情况良好,无明显骨折不愈合或硬化带形成。Smiley-Webster量表7例优,2例良。结论骨科机器人辅助颈椎前路齿状突螺钉内固定术安全、有效,可以作为Ⅱ型齿状突骨折的手术方法。     

齿状突骨折伴寰枢椎不稳的手术治疗

目的:探讨齿状突骨折伴寰枢椎不稳的治疗方案及疗效。方法 :2005年4月~2014年2月共手术治疗Ⅱ、Ⅲ型齿状突骨折患者48例,男33例,女15例,年龄21~74岁,平均43.3±29.0岁。新鲜骨折43例,陈旧骨折5例。按Grauer分型:Ⅱa型12例,Ⅱb型13例,Ⅱc型11例,浅Ⅲ型12例。术前均有外伤史,伴有颈部疼痛和活动受限。术前常规行颅骨牵引,牵引后骨折均有不同程度的复位。根据患者骨折类型、年龄、牵引复位情况、骨质情况、全身条件选择手术方式,22例采用前路单枚中空齿状突螺钉固定,其中1例因C6椎体骨折同时行C6椎体次全切除钛网支撑植骨钢板固定。24例采用经后路寰枢椎椎弓根螺钉固定取髂骨植骨融合,其中1例行一期后路C1/2椎弓根螺钉植骨融合+前路C5椎体次全切除钛网置入钢板内固定术,4例因椎动脉骑跨采用枢椎椎板螺钉固定。2例高龄患者因体质差合并骨质疏松,不能耐受全麻手术,行Halo-vest架固定。随访观察患者骨折融合率、颈椎活动度及神经功能恢复情况。结果:患者均顺利完成手术。前路手术患者中2例在术后1周复查CT时发现骨折移位,1例行翻修手术,取出内固定后重新置钉,再次复查CT示骨折复位满意,6个月后骨折愈合;1例改为后路C1/2椎弓根螺钉内固定植骨融合术,术后4个月植骨融合;2例发生喉上神经损伤,出现饮水呛咳,经对症处理后症状缓解。后路手术患者1例术中出现椎动脉破裂,置入螺钉后出血停止,未特殊处理;1例枢椎椎弓根螺钉进入椎管,无神经损伤症状,未特殊处理。所有患者均未发生脑脊液漏和脊髓损伤。随访12~120个月,平均25±72个月,骨折均达到骨性愈合。前路手术组颈椎屈伸和旋转功能正常,后路手术组颈椎旋转功能有不同程度受限。结论:对于齿状突骨折伴寰枢椎不稳的患者,根据骨折类型、患者年龄、牵引复位情况、骨质情况、全身条件综合考虑,制定个体化的手术方案,可获得良好的治疗效果。     

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 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.     

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.     

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.