3D打印椎弓根导航模板在下颈椎椎弓根置钉中的临床应用

【摘要】 目的：探讨采用优化设计的3D打印椎弓根导航模板辅助下颈椎椎弓根螺钉置入的安全性和准确性。方法：回顾性分析2016年8月~2022年10月在我科行颈椎后路椎弓根螺钉内固定手术的患者42例,年龄32~74岁（50.1±9.8岁）,随访13~25个月（19.6±3.2个月）。根据置钉方式分为导板组（n=22）和徒手组（n=20）：导板组采用优化的椎弓根钻孔导航模板设计方案,3D打印制作下颈椎椎弓根导航模板辅助椎弓根置钉,其中男性12例,女性10例,颈椎损伤或颈脊髓损伤6例,后纵韧带骨化症（OPLL）9例,颈椎管肿瘤5例,脊髓型颈椎病2例;徒手组根据术前颈椎CT测量椎弓根角度、直径等参数,采用徒手置钉,其中男、女各10例,颈椎损伤或颈脊髓损伤4例,OPLL 10例,颈椎管肿瘤5例,脊髓型颈椎病1例。两组患者性别构成、年龄、诊断、术前VAS评分、JOA评分比较无统计学差异（P>0.05）。记录两组患者手术时间、术中出血量;术后1周颈椎CT扫描,按照Kaneyama方法评估椎弓根置钉的准确性：0级,螺钉完全位于椎弓根内;1级,穿破椎弓根的部分<螺钉直径的50%;2级,穿破椎弓根的部分>螺钉直径的50%;3级,椎弓根螺钉完全位于椎弓根外。0级或1级定义为椎弓根置钉准确,2级或3级为螺钉误置。记录患者的围手术期并发症,统计并比较两组术后12个月疼痛视觉模拟评分（VAS）、日本骨科学会（JOA）评分。结果：42例患者手术顺利,导板组手术时间102.2±16.1min,术中出血量89.3±17.7mL;均少于徒手组142.8±20.9min,133.3±34.0mL（P<0.01）。42例患者共置入下颈椎椎弓根螺钉216枚：导板组118枚,其中0级90枚,1级22枚,2级5枚,3级1枚,置钉准确率94.9%（112/118）;徒手组98枚,其中0级48枚,1级36枚,2级10枚,3级4枚,置钉准确率85.7%（84/98）。导板组置钉准确率显著性高于徒手组（P<0.05）。两组患者均未出现螺钉相关神经血管损伤,无内固定松动断裂并发症,术后12个月VAS评分较术前显著性降低（P<0.01）,JOA评分较术前显著性提高（P<0.01）,两组间比较无显著性差异（P>0.05）。结论：3D打印椎弓根导航模板的优化设计方案有助于提高下颈椎椎弓根置钉的准确性。     

3D打印导航模板引导双侧下颈椎前路椎弓根螺钉置钉的可行性

目的 :通过3D打印技术及骨科数字化技术制作下颈椎前路椎弓根螺钉置钉导航模板,观察模板辅助下置钉的准确性。方法:选取正常成人颈椎湿性标本10具(男、女各5具),将椎前软组织剔除,采用64排薄层CT扫描后获取其DICOM格式数据,导入Mimics软件后三维建模并为颈前路椎弓根螺钉选取理想钉道,设计建立螺钉导航模板后导出其STL数据,通过3D打印机快速打印成型。在导航导板引导下进行下颈椎前路椎弓根螺钉置钉,通过X线及CT评价螺钉的准确性。结果:10具尸体分别于C3~T1每节段置入2枚螺钉,共计120枚,根据螺钉的位置将其分为4级:0级,螺钉完全在椎弓根内,共115枚;1级,螺钉穿破椎弓根皮质,穿出部分小于螺钉直径的25%,1枚;2级,螺钉穿破椎弓根皮质,穿出部分为螺钉直径的25%~50%,3枚;3级,螺钉穿出椎弓根部分大于螺钉直径的50%,1枚。5枚穿破椎弓根皮质者2枚穿破椎弓根内侧皮质,3枚穿破外侧皮质,总体准确性为95.8%。结论:在湿性尸体颈椎标本上应用3D打印及骨科数字化技术制作的导航模板辅助行下颈椎前路椎弓根螺钉置钉的准确性高,为临床应用提供了依据。     

新型单椎单侧椎弓根导向模板辅助下颈椎椎弓根个体化置钉

目的探讨新型单椎单侧椎弓根导向模板辅助下颈椎椎弓根个体化置钉的准确性。方法对需要行颈椎后路椎弓根内固定治疗的22例下颈椎患者术前行CT扫描,根据CT扫描资料,利用逆向工程原理及快速成型技术,采用Mimics 16.0和Imageware 12.0软件,制作颈椎三维模型,并设计出个体化的新型单椎单侧椎弓根导向模板,辅助颈椎椎弓根置钉。术后复查颈椎CT评价椎弓根螺钉的位置,按照Lee et al的评定方法将螺钉在椎弓根内的位置分为4级:0级,螺钉完全位于椎弓根内;1级,穿破椎弓根的部分螺钉直径的25%;2级,螺钉直径的25%~50%穿破椎弓根;3级,穿破椎弓根的部分螺钉直径的50%。0级和1级认为置钉满意,2级和3级认为螺钉误置。结果 22例均获得随访,时间6~36个月。22例患者共置入椎弓根螺钉113枚,改为侧块螺钉固定3枚。术后复查CT提示椎弓根螺钉位置107枚为0级,4枚为1级,2枚为2级。仅2例发生误置,置钉准确率达98.2%。其中1级和2级共6枚椎弓根螺钉均穿破椎弓根外侧壁,无椎弓根内侧壁及上、下壁穿破情况。对螺钉穿破外侧壁的患者行椎动脉MRA检查,未见椎动脉损伤。患者均未出现螺钉误置导致的脊髓、神经损伤并发症。结论新型单椎单侧椎弓根导向模板辅助下颈椎椎弓根个体化置钉准确性高,相关并发症少,为下颈椎椎弓根的置入提供了一种新的方法。     

O型臂3D导航与徒手置钉在上颈椎椎弓根螺钉置入中的精确性比较

目的 :比较O型臂3D导航下C1、C2椎弓根螺钉置钉与徒手置钉精确性的差异,探讨O型臂导航在上颈椎椎弓根螺钉置钉中的应用价值。方法:纳入我院C1、C2椎弓根螺钉内固定患者62例,分为导航置钉组(A组)与徒手置钉组(B组)。A组:2014年1月~2015年3月,O型臂导航下行C1、C2后路椎弓根螺钉内固定术22例,男15例,女7例,年龄17~58岁(40.8±12.7岁);B组:2005年3月~2013年12月经徒手置入C1及C2椎弓根螺钉患者40例,男26例,女14例,年龄12~70岁(42.0±15.6岁)。所有患者术后均行颈椎CT平扫,按照Neo等的方法,根据椎弓根螺钉穿破椎弓根皮质的程度将置钉精确性分为四级(0级,螺钉完全处于椎弓根中,没有穿破骨皮质;1级,螺钉穿破皮质2mm,或小于螺钉直径的50%;2级,螺钉穿破皮质≥2mm且﹤4mm,或大于螺钉直径的50%但没完全穿出;3级,完全穿出皮质,螺钉处于椎管或椎动脉孔内),分别评估两组的置钉精确性并比较两组间的差异。结果:A组共置入C1、C2椎弓根螺钉67枚(C1 28枚,C2 39枚),其中0级60枚(89.6%),1级7枚(10.4%),无2级或3级不良置钉;B组共置入C1、C2椎弓根螺钉134枚(C1 64枚,C2 70枚),其中0级116枚(86.6%),1级13枚(9.7%),2级4枚(3.0%),3级1枚(0.7%)。两组间置钉精确性分级(P=0.49)及0级置钉率(P=0.55)均无统计学差异;A组未发现不良置钉,B组不良置钉发生率为3.7%,但组间无统计学差异(P=0.17)。两组均无置钉相关的血管、神经并发症发生。结论:术中O型臂导航与徒手置钉在上颈椎椎弓根螺钉置钉精确性上并无统计学差异,虽然导航能提供清晰的术中3D图像,但该技术未能完全避免置钉时螺钉轻度穿破骨皮质的发生,仍需提高术者与导航系统间的交互作用,完善操作技术,进一步提高置钉精确性。     

下颈椎椎板和侧块作为椎弓根置钉角度参考标志的可靠性

【摘要】 目的：探讨下颈椎椎板和侧块作为椎弓根置钉角度参考标志的可靠性。方法：完整成人颈椎骨性标本10具,男、女各5具,模拟施行下颈椎椎弓根置钉手术;术前对C3~C7进行螺旋CT扫描多平面重建,确定椎弓根进钉轴,并以椎板和侧块作为椎弓根内倾角和上倾角的参考标志,测量椎弓根进钉轴与同侧椎板的夹角（PL角）及与侧块后表面的夹角（PLM角）,术中以相同参考标志和置钉角度置入椎弓根螺钉。术后复查CT并评估椎弓根螺钉置钉的准确率：0级,螺钉完全位于椎弓根内;1级,穿破椎弓根的部分<螺钉直径的25%;2级,螺钉直径的25%~50%穿破椎弓根;3级,螺钉直径>50%穿破椎弓根;2级和3级螺钉为误置。对颈椎标本各节段椎弓根螺钉位置的分级与椎弓根的宽度与高度进行相关性分析。2011年10月~2012年12月,用同样方法对6例患者进行下颈椎椎弓根螺钉置钉手术,评估置钉准确率和并发症情况。结果：10具颈椎标本的下颈椎椎弓根的PL角,C3、C4>C5、C6>C7;PLM角,C3、C4相似文献   

3D打印技术治疗颈椎管狭窄症的初步应用

[目的]探讨3D打印定位导板辅助椎弓根螺钉技术治疗颈椎管狭窄症的置钉准确性及可行性。[方法]2016年6月~2017年5月,对本科收治并采用手术治疗的颈椎管狭窄症患者15例。术前采用3D打印技术设计定位导板,术中依据定位导板确定椎弓根螺钉进钉点和螺钉角度,制备钉道,辅助完成颈椎椎弓根钉置钉。记录手术时间及术中出血量。术后拍摄颈椎CT,使用PSR分级评价螺钉位置准确性。[结果]15例患者共置入椎弓根螺钉92枚。其中PSR Ⅰ级88枚,Ⅱ级4枚,没有出现Ⅲ级螺钉,置钉成功率100%。[结论]3D打印定位导板辅助颈椎椎弓根置钉技术治疗颈椎管狭窄症,螺钉成功率高,临床应用安全性好。     

3D打印体外导板辅助经皮椎弓根螺钉固定术治疗胸腰椎骨折的临床疗效观察

【摘要】 目的：观察3D打印体外导板辅助经皮椎弓根螺钉固定术治疗胸腰椎骨折的临床疗效。方法：回顾性分析2017年8月~2020年8月行经皮椎弓根螺钉固定手术的47例胸腰椎骨折患者的临床资料,男13例,女34例;年龄21~69岁。均为单节段损伤,T12 11例,L1 26例,L2 7例,L3 2例,L4 1例。22例术前制作3D打印个体化体外导板,模拟置钉,术中辅助置钉（导板组）;25例采用X线透视辅助下徒手置钉（徒手组）。对比两组手术时间、置钉时间、术中X线透视次数、术中出血量、术后并发症;采用Neo分级标准评价两组手术置钉等级,计算置钉准确率;在术前、术后X线片上测量骨折椎体前缘高度和Cobb角,计算椎体矢状面指数,评价骨折复位及矫正情况;术前和术后1d、7d及1年时进行疼痛视觉模拟评分（visual analogue scale,VAS）评分、日本骨科协会（Japanese Orthopedics Association,JOA）评分和Oswestry功能障碍指数（Oswestry disability index,ODI）评定。结果：导板组手术时间、置钉时间、术中X线透视次数、术中出血量分别为63.57±12.18min、23.69±3.63min、15.26±4.15次、48.82±13.72ml;徒手组分别为85.56±16.27min、41.36±8.12min、26.93±6.93次和74.35±18.64ml;导板组均少于徒手组,差异有统计学意义（P<0.05）。导板组0级置钉119枚,1级置钉3枚,置钉准确率为97.54%;徒手组0级置钉128枚,1级置钉10枚,2级置钉1枚,置钉准确率为92.09%,导板组置钉准确率高于徒手组,差异有统计学意义（P<0.05）。术后两组的椎体前缘高度、椎体矢状面指数和Cobb角与术前相比均有显著性改善（P＜0.05）;两组同时间点比较均无统计学差异（P＞0.05）。两组术后VAS评分、JOA评分和ODI与术前比较均有显著性改善,差异有统计学意义（P<0.05）,两组间同时间点比较均无统计学差异（P＞0.05）。两组患者术后伤椎均达到骨性愈合,均未出现术后并发症。结论：3D打印体外导板辅助经皮椎弓根螺钉固定术治疗单节段胸腰椎骨折可取得良好效果,与徒手经皮椎弓根螺钉固定术相比能够显著性提高置钉准确率,并缩短手术时间、减少术中辐射暴露。     

颈椎椎弓根螺钉误置的临床特征分析

目的:观察颈椎椎弓根置钉的准确性,分析螺钉误置的临床特征。方法:32例施行颈椎椎弓根置钉手术患者,男22例,女10例;年龄25~74岁(51.5±13.6岁)。颈椎骨折/脱位16例,颈椎后纵韧带骨化8例,颈椎多节段椎间盘突出1例,颈椎管内肿瘤7例(神经鞘瘤3例,脊膜瘤3例,室管膜瘤1例)。术前进行颈椎CT三维重建,确定椎弓根螺钉的进钉点,并测量椎弓根的内倾角、矢状面角度及直径、长度等参数;术中在C型臂X线机透视辅助下置入椎弓根螺钉;术后复查颈椎CT观察椎弓根螺钉位置,按照Lee等的方法判断椎弓根螺钉位置准确性:0级,螺钉未穿破椎弓根;1级,螺钉穿破椎弓根25%的螺钉直径;2级,螺钉穿破椎弓根25%,但50%的螺钉直径;3级,螺钉穿破椎弓根50%的螺钉直径。2级和3级判为螺钉误置,分析椎弓根螺钉误置的特点;观察血管神经损伤等并发症情况。结果:32例患者中因术中置钉困难更改为侧块螺钉3枚,改为寰椎椎板钩1枚,共置入颈椎椎弓根螺钉147枚(上颈椎40枚,中下颈椎107枚),椎弓根螺钉位置0级53枚,1级67枚,2级17枚(上颈椎2枚,下颈椎15枚),3级10枚(上颈椎1枚,下颈椎9枚)。椎弓根螺钉总误置率为18.3%(2级+3级);外侧壁穿破17枚,下壁5枚,上壁4枚,内侧壁1枚。上颈椎椎弓根螺钉的误置率(7.5%)显著低于中下颈椎(22.4%)(P0.05);椎弓根外侧壁穿破率(11.5%)高于上壁(2.7%)、下壁(3.4%,)及内侧壁(0.7%)(P均0.01)。5例患者6枚螺钉术中椎弓根钉道攻丝后活动性出血,予骨蜡封堵及置入螺钉后即止血,无血肿或脑缺血梗死并发症。3例患者术后出现上肢神经根刺激症状,予颈椎制动、神经营养治疗,分别于术后1个月、3个月、4个月好转。结论:颈椎椎弓根螺钉误置率较高,但相关并发症较少;穿破椎弓根外侧壁多于内侧壁、上壁或下壁;中下颈椎椎弓根螺钉的误置率高于上颈椎。     

数字化导航模板在颈椎椎弓根螺钉置入中的应用

目的 :评价个体化导航模板辅助颈椎椎弓根螺钉置入的准确性和安全性。方法 :2010年8月~2013年8月,对25例需要行颈椎椎弓根螺钉内固定的患者术前行64排螺旋CT连续扫描,计算机重建颈椎三维模型、设计颈椎椎弓根的最佳进钉通道,获取每个颈椎椎板的解剖形态,设计与颈椎椎板吻合的反向模板,并模拟螺钉的最佳进钉通道,形成单侧定位导向孔的导航模板。利用3D打印技术打印颈椎模型和导航模块,通过术前模拟置钉测量出每个椎弓根的螺钉通道长度及椎弓根宽度,术中采用导航模板辅助置入椎弓根螺钉,术后行CT扫描评价螺钉位置,记录有无与螺钉置入相关的并发症。结果:利用导航模板辅助置入颈椎椎弓根螺钉共164枚,其中152枚完全在椎弓根内,4枚螺钉穿破椎弓根内侧皮质,8枚螺钉穿破椎弓根外侧皮质,无椎弓根上方、下方穿破的螺钉,未发现与置钉相关的椎动脉、神经根和颈髓等损伤的症状。结论:个体化导航模板辅助颈椎椎弓根螺钉置入可以提高置钉的准确率,增加颈椎手术的安全性。     

3D打印个体化导航模板在胸椎和颈椎椎弓根螺钉植入的临床应用

目的 研究数字化(3D)打印技术的个性化导航模板设计在胸椎和颈椎手术个性化置钉应用的准确性和安全性。方法 2014年7月至2014年11月,对7例需要行胸椎、颈椎椎弓根螺钉植入手术的患者术前通过CT扫描、Mimics软件三维重建建立三维仿真模型。并使用Geomagic软件设计最佳的内固定钉道,然后根据钉道设计导航模板,用3D打印机打印导航模板,用于手术时辅助置钉;术中辅助植入胸椎、颈椎椎弓根螺钉共24枚,术后CT扫描评价螺钉位置,记录有无与螺钉植入的相关并发症。结果 通过导航模板辅助植入的24枚椎弓根螺钉,23枚完全在椎弓根内,1枚穿破椎弓根外壁,穿出距离均小于1.2 mm,椎弓根穿破率为4%,植钉准确率为96%,螺钉位置可接受率为100%。无一例出现螺钉植入有关的神经、血管损伤等并发症。结论 3D打印个体化导航模板辅助胸椎、颈椎椎弓根螺钉植入的植钉准确性高、安全。     

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.     

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.     

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.     

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.     

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.     

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.     

Systemic analgesia adapted to the children's condition

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.     

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.