后路一期全脊椎切除术治疗复发性脊柱肿瘤

目的 探讨后路一期全脊椎切除术在治疗复发性脊柱肿瘤中的临床应用.方法 2010年1月至2013年10月共6例复发性脊柱肿瘤患者在中山大学孙逸仙纪念医院骨科接受后路一期全脊椎切除术.其中男性3例,女性3例;年龄27 ～ 46岁,平均33.2岁.肿瘤位于胸椎5例,腰椎(L1)1例.病理包括骨巨细胞瘤3例,乳腺癌、鼻咽癌、肺癌骨转移各1例.分析6例患者手术时间、出血量、切除节段、手术切缘、神经功能及手术并发症发生情况.结果 切除1节段1例,2节段2例,3节段3例.手术时间7.5～12.0 h,平均8.9h;出血量2500～4500 ml,平均3 116 ml;无手术相关脊髓损伤.术后病理证实边缘无残留.无围手术期死亡病例.合并硬膜撕裂1例,胸膜破裂2例,胸腔大量积血1例.随访12 ～47个月,平均随访23.2个月;至末次随访未发现局部复发.美国脊髓损伤协会神经功能分级:3例术前E级患者术后仍为E级,2例术前C级患者术后恢复至D级,1例术前B级患者无明显恢复.结论 部分复发性脊柱肿瘤仍适合后路全脊椎切除术,但需严格选择手术适应证.     

一期经后路全脊椎整块切除术治疗胸腰椎肿瘤

目的探讨一期经后路全脊椎整块切除术治疗胸腰椎肿瘤的近期疗效。方法采用经后路全脊椎整块切除术治疗8例胸腰椎肿瘤患者。观察手术时间、术中出血量、局部疼痛,以及肿瘤复发、植骨融合、脊柱稳定性情况。结果手术时间为4.5~7(5.5±1.2)h。术中出血量为1 600~4 000(2 500±1 000)ml。患者均获得随访,时间8~48个月。近期疗效均较满意,局部疼痛有不同程度改善。未发现复发或转移,植骨融合良好,无钛网移位及脊柱失稳,无断钉、断棒现象。结论一期单纯经后路全脊椎整块切除术能提高脊柱肿瘤病灶切除率、降低局部复发率,近期随访疗效满意。     

伴脊髓压迫的脊椎侵袭性血管瘤手术方式选择

目的 :探讨伴有脊髓压迫的脊椎侵袭性血管瘤的手术治疗方法。方法 :2000年1月~2015年10月,收治26例伴有脊髓压迫的脊椎血管瘤患者,男11例,女15例,年龄15~69岁(23.0±4.5岁),单发性血管瘤6例,多发性20例,责任节段位于颈椎6例,胸椎18例,腰椎2例。术前Frankel分级A级1例,C级5例,D级18例,E级2例,硬膜外脊髓压迫(ESCC)分级Ⅰ级5例,Ⅱ级15,Ⅲ级6例。18例术前穿刺病理检查明确诊断,8例行术中快速病理检查确诊。手术方式包括单纯减压、椎体成形、内固定术11例;病椎切除、重建术15例,其中前路椎体肿瘤切除减压重建术6例,后路全脊椎切除重建术8例,一期前后路枢椎肿瘤切除重建1例。随访评估术中出血量、围手术期并发症、肿瘤控制效果、脊髓神经功能、脊柱稳定性重建等。结果:病椎切除组15例患者术中出血量平均为3927±4137ml,减压加椎体成形组11例情况出血量为1355±703ml。1例术后胸腔出血,1例术后迟发性感染,经对症处理后痊愈。随访时间12~194个月(75±51个月),共4例出现肿瘤进展,3例为后路减压术后,2例再行病椎切除,1例行立体定向放射外科治疗;1例为枢椎血管瘤,生育后肿瘤复发进展,行后路减压和放疗,恢复良好。4例患者出现内固定相关并发症,包括3例内固定松动,1例内固定断裂,均行内固定翻修术。26例患者术后半年脊髓功能Frankel分级D级4例,E级22例。结论:伴有脊髓压迫的脊椎侵袭性血管瘤需要手术治疗,病椎切除能较好控制肿瘤,但手术创伤大,术中出血和术后并发症多;姑息减压结合椎体成形术能挽救脊髓功能,但有肿瘤复发风险,复发后再行病椎切除手术可取得良好效果。     

前路内镜辅助后路改良一期全脊柱整块切除脊柱重建术治疗胸椎肿瘤

目的探讨前路内镜辅助后路改良一期全脊柱整块切除脊柱重建术治疗胸椎肿瘤的疗效。方法采用经前路内镜辅助联合后路改良全脊椎整块切除、脊椎重建术治疗4例胸椎肿瘤患者。记录手术时间、术中出血量、输血量,观察局部疼痛和脊髓功能恢复以及肿瘤复发、植骨融合、脊柱稳定情况。结果手术时间250~295(269.3±39.8)min,术中出血量850~1 550(1 232.5±37.9)ml,输血量300~1 000(675±100)ml。4例均获得随访,时间3~24个月。1例发生胸腔积液,经引流抗感染后好转。患者局部疼痛和脊髓功能均有不同程度改善。1例肺癌转移患者术后3个月因肺癌复发死亡;其他患者术后3、6、12个月复查未见脊柱肿瘤复发,植骨融合良好,无钛网移位及脊柱失稳,无断钉、断棒现象。结论前路内镜辅助后路改良一期全脊柱整块切除术能提高胸椎肿瘤病灶切除率、减少术中出血量及输血量,手术安全,效果较好。     

全脊椎切除及脊柱稳定性重建治疗颈胸段脊柱肿瘤

目的探讨全脊椎切除术及脊柱稳定性重建治疗颈胸段脊柱肿瘤的临床效果。方法回顾性分析2008年3月~2015年4月我院收治的50例行全脊椎切除术及脊柱稳定性重建的颈胸段脊柱肿瘤患者临床资料,术前Frankel脊髓损伤分级:A级2例,B级7例,C级14例,D级22例,E级5例。结果本组患者均顺利完成手术,手术时间为3.4~10.8 h,平均(6.9±1.3)h,术中出血量1 440~2 430 ml,平均(2 050±107)ml,围术期内无死亡,患者伤口愈合良好,疼痛均明显减轻。术后脊髓神经功能Frankel分级为C级3例,D级5例,E级42例,较术前有显著改善(P0.05),患者行走功能亦较术前明显改善(P0.05)。术后随访12个月,所有患者内固定稳定,植骨融合满意。术前伴神经功能损害的9例患者得到完全恢复。有1例骨母细胞瘤和2例甲状腺滤泡型转移癌局部复发。结论根据颈胸段脊柱肿瘤患者的病症特性,实施相应的全脊椎切除术和合理的脊椎稳定性重建,可有效改善患者的脊柱损伤程度和神经功能,临床效果显著,术后并发症发生率低。     

全脊椎切除及脊柱稳定性重建治疗颈胸段脊柱肿瘤的疗效分析

目的 :探讨颈胸段脊柱肿瘤全脊椎切除的手术方式、脊柱重建策略及治疗效果。方法 :回顾性分析我院自2008年1月~2013年12月行全脊椎切除术治疗的颈胸段脊柱肿瘤病例11例,病理诊断包括骨巨细胞瘤5例,骨母细胞瘤1例,Ewing肉瘤1例,浆细胞性骨髓瘤1例,甲状腺滤泡型转移癌2例,前列腺转移癌1例。患者均有不同程度的胸背部疼痛,术前VAS评分为7.45±0.82分;脊髓损伤神经功能Frankel分级B级1例,C级3例,D级6例,E级1例。所有病例术前根据Tomita脊柱肿瘤外科分期评估均为间室外病变。4例C7~T1段肿瘤行一期前后联合入路全脊椎切除,前方钛网、钛板重建;7例T2~T4段肿瘤行单一后路整块全脊椎切除(TES),前方单纯钛网重建。两种术式后方均为钉棒系统重建。观察患者术中术后并发症以及脊柱重建稳定性情况。结果:手术时间298~573min,平均423.9min;术中失血量800~3800ml,平均2077ml。4例术中胸膜破裂,2例术后神经功能一过性下降,7例术中结扎病椎神经根,残留轻度胸前区不适。所有患者均获随访,平均随访34.7个月,1例前列腺转移癌患者死亡,其余均无局部复发。术后患者疼痛明显改善,VAS评分由术前7.45±0.82分下降至术后2.55±0.69分(P<0.05)。术后神经功能2例(术前D级1例,E级1例)保持原有水平,余均获得改善,均未出现内固定失败。结论:全脊椎切除治疗颈胸段脊柱肿瘤可以获得满意的局部控制,缓解疼痛,改善神经功能,应根据肿瘤位于颈胸段脊柱近端(C7~T1)或远端(T2~T4)而制定个体化手术方式及脊柱重建策略。     

经病椎短钉内固定术治疗短节段脊柱结核的临床分析

[目的]探讨经病椎置入短椎弓根螺钉后路内固定治疗短节段脊柱结核的临床疗效。[方法]收集2012年9月~2015年9月西安市胸科医院收治的短节段脊柱结核患者24例,均行经病椎短椎弓根螺钉内固定术并术后明确诊断为脊柱结核。其中男13例,女11例;年龄20~56岁,平均(36.3±9.7)岁。病变节段为T9~L5(均≤3个节段)。记录患者手术时间、出血量、切口愈合情况以及结核中毒症状的变化;观察术前及术后的神经功能恢复情况及术后并发症,术前神经功能分级按美国脊柱损伤协会(ASIA)神经功能分级,其中C级4例、D级8例、E级12例;比较术前、术后2周和术后1年的Cobb角变化;复查术后X线片和CT判断植骨融合情况。[结果]手术时间60~150 min,平均(85.35±21.40)min,术中出血量50~260 ml,平均(127.03±55.90)ml。随访12~24个月,平均(17.37±3.88)个月,随访期内结核均无复发,无脓液及窦道形成,无螺钉置入病椎相关的并发症。所有患者结核中毒症状和脊柱病变区疼痛均消失。末次随访时ASIA分级D级1例,E级23例。术后2周复查Cobb角明显变小,由术前的(16.75±6.61)°降至术后的(6.95±2.80)°及末次随访的(7.42±3.11)°,随访角度无明显丢失。1年随访时脊柱椎体病灶基本愈合,未见骨不连、假关节形成,无内固定松动及断裂,无植骨粒吸收、消失。[结论]经病椎置入短椎弓根螺钉行内固定术与后路植骨融合术,治疗短节段脊柱结核,手术安全可靠,随访效果满意。     

脊柱肿瘤的全脊椎切除术及脊柱稳定性重建

目的探讨对脊柱肿瘤行全脊椎切除术的可行性与临床价值,以及重建脊柱稳定性的可靠方法。方法对27例椎体和附件结构均遭破坏的脊柱肿瘤采用全脊椎切除及内固定重建技术进行治疗,其中包括上颈椎至下腰椎的良、恶性及转移性肿瘤,手术切除1～3节脊椎。结果23例获完整随访,随访时间7～96个月(平均25个月)。1例L5恶性神经纤维瘤及1例C6,7巨细胞瘤于术后10个月及12个月复发,患者放弃治疗;1例C2～4脊索瘤术后1年复发,再次手术效果良好;其余20例未见复发。25例术前伴神经功能损害者,术后有23例获显著改善。结论全脊椎切除术为治疗全脊椎受累脊柱肿瘤的有效方法;切除1～3节脊椎的脊柱可由相应内固定系统进行可靠的稳定性重建。     

一期后路全脊椎切除术治疗伴脊髓压迫的肾源性脊柱转移癌

目的探讨一期后路全脊椎切除术治疗伴有脊髓压迫的肾源性脊柱转移癌的外科策略及临床疗效。方法2003年1月—2012年12月,第二军医大学附属长征医院骨肿瘤科共收治35例伴有脊髓压迫的肾癌脊柱转移患者,均行一期后路全脊椎切除术、脊髓减压并内固定重建术。对所有患者病史、影像学资料、手术时间、术中出血量、切除重建策略、手术并发症及临床疗效进行分析。采用美国脊髓损伤协会(ASIA)分级评价患者神经功能状况,采用视觉模拟量表(VAS)评分对患者疼痛程度进行评估。所有患者术后接受放化疗以及双膦酸盐治疗。结果所有手术顺利完成,手术时间为(296±35)min,术中出血量为(2 160±240)m L,术中无大血管或脊髓损伤,无脑脊液漏等并发症。所有患者均获得随访,随访时间为(73.2±8.7)个月。术后1例ASIA A级患者恢复至B级;3例ASIA B级患者恢复至C级、D级各1例,1例因压迫时间过长无恢复;2例ASIA C级患者1例恢复至D级,1例仍然为C级;11例ASIA D级患者9例恢复至E级,2例仍然为D级;18例ASIA E级患者无变化。所有患者术后VAS评分均降低,与术前相比差异有统计学意义(P0.05)。随访时1例患者术后18个月因肿瘤复发压迫颈髓致瘫痪,并肺部转移,致呼吸衰竭死亡;2例患者复发,1例行手术治疗,1例放弃治疗;3例患者带瘤生存;其余患者末次随访时未见复发征象。结论一期后路全脊椎切除术治疗伴脊髓压迫的肾癌脊柱转移能够安全有效地解决患者局部压迫症状,改善其神经功能,术后综合治疗能延长患者的生存期。     

脊柱肿瘤的手术治疗

目的 :探讨对于脊柱肿瘤一期全脊椎切除及脊柱稳定性重建的手术方法和临床效果。方法 :对 12例脊柱肿瘤行前、后路或前、后联合入路Ⅰ期全脊椎切除、脊髓减压 ,椎间植骨融合、内固定术。结果 :术后 11例获得随访 ,按照Frankel分级较术前均有 1级以上提高 ,所有患者局部疼痛症状消失。术后复查平均植骨融合时间 3个月。1例脊索瘤术后 1年复发 ,1例巨细胞瘤术后 9个月复发。结论 :针对脊柱肿瘤的性质、部位 ,通过不同的手术入路行一期全脊椎切除、植骨融合内固定 ,彻底切除肿瘤 ,重建脊柱稳定性并体现了个体化的治疗方向     

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.