数字化三维重建模拟前路枕骨髁螺钉置钉

目的 :使用数字化三维重建技术测量前路枕骨髁螺钉的相关置钉参数,探讨前路枕骨髁螺钉置入的可行性和安全性。方法:选取宁波市第六医院共50例枕颈部形态正常者的上颈椎螺旋CT扫描图像,男30例,女20例,年龄42.2±8.6岁(23～68岁)。排除感染、肿瘤、解剖畸形、骨折脱位、退行性变及严重骨质疏松,将CT数据导入Mimics软件,对枕骨及寰椎进行三维CT重建后,模拟前路置入直径3.5mm的枕骨髁螺钉,测量进钉点至枕骨髁内侧缘及寰枕关节面的距离、螺钉与舌下神经管的最短垂直距离、进入枕骨髁骨质内的钉道长度,再用3-matic软件测量螺钉的头倾角及外倾角,将螺钉各置钉参数进行统计学分析。结果:共模拟成功置入100枚前路枕骨髁螺钉,三维模型观察均无枕骨髁内外侧壁、寰枕关节面及舌下神经管的损伤。前路枕骨髁螺钉各置钉参数左右两侧比较均无统计学差异(P0.05)。进钉点距枕骨髁内侧缘水平距离及寰枕关节面垂直距离分别为3.28±0.54mm、2.84±0.45mm,螺钉头倾角、外倾角、距离舌下神经管最短垂直距离及钉道长度分别为4.07°±2.40°、33.09°±4.37°、4.76±0.74mm、21.54±2.01mm。结论:通过数字化三维重建模拟前路枕骨髁螺钉置钉,显示正常成人枕骨髁有足够的体积空间容纳直径3.5mm的前路枕骨髁螺钉置入,前路枕骨髁螺钉技术是治疗枕颈不稳时颅侧固定的一种安全可行的方法。     

数字化三维重建模拟后路枕骨髁螺钉置钉

目的:利用数字化三维重建技术测量枕骨髁螺钉的最佳置钉参数,探讨后路枕骨髁螺钉置入的安全性及各置钉参数间的相关性。方法:选取50例枕颈部形态正常者的上颈椎螺旋CT扫描图像,男25例,女25例,年龄25~60岁(38.5±7.6岁)。排除骨折脱位、感染、肿瘤、畸形及退行性变,将数据导入Mimics软件,对枕骨及寰椎进行三维CT重建,模拟置入直径3.5mm的枕骨髁螺钉,测量枕骨髁长、宽、高、进钉点至枕骨内侧缘和颅底部的距离,并通过3-matic软件测量枕骨髁螺钉进钉长度、头倾角、内倾角及与枕骨切线间的切线角,比较枕骨髁解剖学参数与螺钉置钉参数间的差异。结果:共模拟置入100枚枕骨髁螺钉,三维模型大体观察均无舌下神经管、寰枕关节面和枕骨髁内外侧壁的损伤。男、女枕骨髁解剖学参数及螺钉进钉点参数、置钉后枕骨髁螺钉置钉参数左右两侧比较均无统计学差异(P0.05)。男性枕骨髁解剖学长、宽、高、进钉点距枕髁内侧缘水平距离及距颅底垂直距离分别为22.00±1.67mm、11.27±1.21mm、10.72±1.13mm、5.37±0.10mm及2.95±0.47mm,女性分别为21.07±1.43mm、10.64±0.81mm、9.62±0.95mm、5.05±0.10mm及3.04±0.48mm,女性枕骨髁长、宽、高及进钉点距枕髁内侧缘水平距离均显著性小于男性(P0.05),进钉点距颅底垂直距离与男性无统计学差异(P0.05);置钉后男性头倾角、颅底切线角、内倾角及进钉长度分别为3.90°±2.01°、12.45°±4.73°、28.15°±4.53°、22.47±1.48mm,女性分别4.19°±2.01°、11.25°±4.61°、30.00°±4.70°、21.59±1.62mm,女性进钉长度较男性短(P0.05),头倾角、颅底切线角及内倾角男女性无统计学差异(P0.05)。头倾角与切线角间存在正相关性(r=0.519,P0.05),与其余置钉参数间无相关性(P0.05)。结论 :国人女性枕骨髁解剖学参数与男性存在差异,枕骨髁三维重建下模拟螺钉置入显示男女性枕骨髁均可安全容纳螺钉置入固定,理论上切线角可结合进钉点及内倾角指导枕骨髁螺钉的安全置入。     

前路经寰枢关节螺钉内固定行枕颈融合的解剖学研究

目的：寻求前路经寰枢关节螺钉内同定行枕颈融合可行性的解剖学依据。方法：对30例正常国人行枕寰枢区三维CT重建，测量与内同定有关的解剖径线长度及角度大小，观察舌下神经管与枕骨髁的相对位置关系：并以测得的数据为依据在8具人体干燥枕寰枢标本上行螺钉内固定，三维CT检查内固定位置。结果：枕骨髁关节面的宽度为11．23～17．08mm，后1／3宽度为3．74～5．69mm，寰椎上关节面的长度为11．65～20．71mm，枕骨髁高度为4130～10．62mm，舌下神经管的位置相对恒定，表明枕颈部解剖结构适于行前路枕颈融合术；内同定后三维CT检查未见毗邻组织损伤。结论：前路经寰枢关节螺钉内同定行枕颈融合在解剖上是可行的，舌下神经管与枕骨髁的位置关系相对恒定，但少部分舌下神经管位于枕骨髁的后外侧，会使进针变得危险。     

前路经枕寰枢关节螺钉内固定术的可行性及安全性研究

目的 通过影像学方法探讨前路经枕寰枢关节螺钉内固定术的可行性和安全性. 方法 随机选取30例健康成人头颈部CT血管造影检查资料,男18例,女12例;年龄21～55岁,平均33.6岁.利用Vitreal 4.0软件测量理想钉道角度、长度及其与椎动脉的距离.在此基础上,对2具防腐枕颈部标本进行模拟手术,行X线及CT检查以明确螺钉位置. 结果 从入钉点平面至锚定点平面椎动脉在形态上有5个恒定的生理弯曲;入钉点平面处两侧椎动脉间距为(25.59±1.04) mm;螺钉内固定理想钉道角度:冠状面上外倾角为18.62°±2.17°,矢状面上后倾角为24.35°±3.02°;理想钉道长度为(35.95±2.16) mm.理想钉道与椎动脉的关系于寰椎横突孔上方稚动脉弯曲平面最为密切,其距离为(3.66±0.55)mm.模拟手术的影像学检查证实钉道角度、长度均位于参考值范围内,无穿出骨质及进入舌下神经管者. 结论 国人采用前路经枕寰枢关节螺钉内固定在解剖上是可行的,钉道与椎动脉之间有一定的安全距离,但术中必须严格控制钉道方向.     

基于CT数据的腰椎皮质骨轨迹螺钉经皮置入的可行性研究

目的通过腰椎CT扫描及三维重建图像模拟置入皮质骨轨迹螺钉并进行形态学测量, 探讨经皮皮质骨轨迹螺钉置入的可行性。方法收集100例成人腰椎病变患者的CT数据, 利用Mimics 17.0软件进行CT三维重建, 以腰椎椎弓根最小冠状断面的内缘与下缘交界处在椎板上的投影点为进钉点, 测量头倾角、外倾角、最大螺钉长度、最大螺钉直径、轨迹与棘突的距离、上终板比率等参数, 同时利用三维重建图像观察该轨迹与棘突的关系。结果 L1～L5的外倾角分别为9.3°(8.9°, 9.8°)、9.6°(8.9°, 9.8°)、10.4°(9.5°, 11.3°)、11.81°±1.24°和13.6°(12.5°, 14.5°), 头倾角分别为26.6°(26.0°, 27.0°)、26.2°(25.7°, 26.5°)、26.9°(26.5°, 27.4°)、25.94°±0.92°和24.3°(22.7°, 25.4°), 头倾角、外倾角各节段间的差异均有统计学意义。L1～L5的最大螺钉直径分别为(5.65±0.49) mm、(6.38±0.60) mm、(6.91±0.67) mm、(7.42±0.76) ...     

经口咽入路枕骨髁螺钉置钉的影像学研究

目的:探讨前路经口咽入路枕骨髁置钉的可行性及置钉的技术参数。方法:用Mimics软件对40例被检查者共80个枕骨髁的CT数据(层厚1mm)进行三维重建。女17例,男23例,年龄19~63岁,平均38.7岁;均无上颈椎手术史;CT扫描证实上颈椎结构完整,无上颈椎解剖畸形、感染、肿瘤、骨折。于枕骨髁的前方选定3个进钉点(中间点、内侧点、外侧点),中间进钉点位于寰椎侧块中线与枕骨大孔前缘水平线相交处,中间进钉点向两侧旁开5mm作为外侧进钉点及内侧进钉点。分别于各个进钉点模拟置入直径3.5mm枕骨髁螺钉。螺钉尾端位于枕骨髁与枕骨大孔连接处水平。比较各个进钉点间置钉成功率、螺钉长度及外倾角的安全范围。对于临床上具备可行性的进钉点,间隔1°调整进钉角度,比较不同角度置钉时置钉成功率的变化。结果:外侧进钉点置钉成功率为100%,螺钉长度为13.5~21.6mm,钉道外倾角度最小值为-19.5°~5.6°,最大值为-8.1°~24.9°;中间进钉点分别为88.6%,16.3~24.2mm,-4.1°~29.7°,12.6°~34.2°;内侧进钉点分别为72.5%,20.4~27.0mm,16.3°~40.3°,27.2°~44.8°;3个进钉点之间在置钉成功率、螺钉长度上均有显著性差异(P<0.01)。中间及外侧进钉点具备临床可行性,但没有固定的外倾角度可以满足所有螺钉安全置入,其中中间进钉点螺钉外倾20°达到最大的置钉成功率68.75%,而外侧进钉点平行矢状面置钉时达到最大置钉成功率80%。结论:经口咽前路枕骨髁置钉具备可行性,中间及外侧进钉点明显优于内侧进钉点,进钉点及钉道方向必须根据患者术前三维CT数据确定。     

后路枕骨髁螺钉内固定系统的生物力学研究

目的 :通过对后路枕骨髁螺钉内固定系统治疗枕颈部不稳的生物力学研究,为其临床应用提供理论依据。方法:选取6具年龄32~55岁,身高155~180cm的颈椎尸体标本,不做手术处理建立正常模型,切断标本的寰椎横韧带、齿状突尖韧带、翼状韧带,制作枕颈不稳模型,枕骨髁螺钉的置钉固定建立枕骨髁螺钉内固定模型,分别给予三个模型枕骨1.5N·m的屈伸、侧弯、旋转力矩,测量标本C0~C1与C0~C2的前屈后伸、侧弯、旋转的运动范围(range of motion,ROM),分析比较正常模型、失稳模型及内固定模型的运动范围改变,评价枕骨髁螺钉内固定系统的生物力学有效性。结果:在C0~C1节段上,正常模型的前屈、后伸、侧弯、旋转活动度分别为:14.13°±0.71°、7.60°±0.43°、3.77°±0.27°、5.42°±0.44°,失稳模型的活动度分别为23.57°±2.26°、11.96°±1.44°、5.21°±0.29°、7.13°±0.67°,枕骨髁螺钉内固定模型的活动度分别为7.53°±0.77°、3.79°±0.64°、2.56°±0.34°、0.89°±0.31°;而在C0~C2节段上,正常模型的前屈、后伸、侧弯、旋转活动度分别为:19.72°±0.71°、17.62°±0.97°、7.55°±0.51°、51.46°±3.11°,失稳模型的活动度分别为30.57°±2.32°、23.85°±0.91°、9.37°±0.55°、68.91°±6.25°,枕骨髁螺钉内固定模型的活动度分别为11.30°±0.66°、9.19°±0.63°、5.12°±0.59°、7.39°±0.76°。失稳模型的活动度大于正常模型,正常模型的活动度大于固定模型。结论:枕骨髁螺钉内固定系统能有效减少枕颈部的前屈、后伸、侧弯、旋转的运动范围,充分证明了该固定技术具有可靠的生物力学稳定性。     

三维打印个体化导航模板在枕骨髁螺钉固定技术中的应用研究

【摘要】 目的：探讨一种基于三维打印技术制备个体化枕骨髁螺钉导航模板的可行性,并对该方法辅助置钉的准确性和安全性进行评估。方法：选取20具成人尸体的枕颈部标本,将其CT扫描数据导入Mimics软件,对枕骨至枢椎水平行选择性三维重建,观察并测量枕骨髁相关解剖结构以确定置钉参数。在计算机三维模型上虚拟枕骨髁螺钉钉道及其导向通道,设计与枕骨后部结构相贴合的阴模,将阴模与导向通道整合后利用三维打印技术成型,制作出枕骨髁模型及对应的个体化导航模板。然后导航模板辅助下分别于模型和尸体标本置入双侧枕骨髁螺钉,并通过解剖观察及CT扫描评估置钉准确性。结果：枕骨髁的大体形态及毗邻解剖结构个体差异较大,虚拟置钉后测得置钉轴位内倾角、矢状位倾角和进钉点至寰枕关节面的垂直距离分别为30.2°±6.3°、8.1°±2.6°和3.69±0.42mm。根据置钉参数设计并打印出20个枕骨髁模型及对应的个体化导航模板,在其辅助下成功置入双侧枕骨髁螺钉共40枚,置钉耗时（60.1±9.3）s。术后解剖观察及CT扫描提示所有螺钉均准确置入枕骨髁内。结论：使用Mimics软件能够根据CT扫描结果利用三维打印技术制作出个体化枕骨髁螺钉导航模板,辅助置钉准确性高,操作简单,为枕骨髁螺钉的精确置入提供了新思路。     

枢椎后路棘突螺钉固定技术及其解剖学研究

目的 明确枢椎后路棘突螺钉固定的解剖学可行性和技术参数,为临床应用提供参考.方法 选取30具枢椎标本,仔细解剖以清楚地暴露椎板和棘突.测量枢椎棘突根部1/2的中点、中部和后部1/2的中点高度;棘突根部的头侧1/2的中点、中部和根部的尾侧1/2的中点厚度(精确到0.01 mm).选取20具枢椎标本,以棘突基底部为进钉点,双侧平行置入棘突螺钉,通过CT重建,测量棘突的宽度、螺钉进钉角度、钉道长度及钉尖与脊髓、椎动脉的距离.结果 枢椎棘突平均高度和厚度各自为(12.90±1.30)mm和(18.86±1.17)mm.所有棘突螺钉均成功置入枢椎棘突,未见螺钉侵犯椎管、横突孔和棘突劈裂.重建CT测量棘突中份基底部的平均宽度为(20.7±1. 3)mm;棘突螺钉在横断面的前倾角度为1.8°±1.0°,在横断面上和矢状面上几乎均是平行.螺钉钉道长度为(19.7±1. 1)mm,螺钉钉尖与椎动脉距离为(20.2±3.1)mm,螺钉钉尖与脊髓距离为(8.3±2.6)mm,上下位左右侧螺钉角度与椎动脉和脊髓的距离数据略有不同,但差异无统计学意义(P＞0.05),但上位螺钉钉道长度(18.4±1.1)mm明显短于下位螺钉钉道长度(20.3±1.2)mm,差异有统计学意义(t=3.566,P＜0.01).结论 枢椎后路棘突螺钉具有一定的解剖学可行性,也许可以作为枢椎后路固定的一种补充内固定方法,但临床应用之前,尚需进一步的生物力学研究.     

髋臼后柱骨折经皮逆行拉力螺钉固定的三维重建模型研究

目的 为髋臼后柱骨折经皮逆行拉力螺钉固定提供应用解剖学基础. 方法 收集60个正常成人骨盆的螺旋CT扫描数据,重建骨盆三维模型.模拟逆行拉力螺钉固定,在髋臼后柱置入虚拟三维圆柱体.计算其最大直径、长度、置入角度以及置入点(A)到坐骨结节远端(B)的距离.同时在相同的三维重建骨盆模型上,垂直髋臼内侧面对后柱进行重切,每间隔1 cm取一个截骨面,测量每个截骨面的内外径和上下径. 结果 男性半骨盆58个,女性半骨盆62个.虚拟三维圆柱体的平均最大直径为(13.16±1.45)mm,虚拟三维圆柱体与水平面、冠状面和矢状面的夹角分别为72.02°±6.05°、14.71°±6.98°和8.61°±3.96°,置入点位于坐骨结节内外侧缘的中线上,AB间距离为(15.18±1.97)mm.平均最小内外径和上下径分别为20.11 mm、19.19 mm,明显大于虚拟三维圆柱体的平均最大直径.虚拟三维圆柱体的直径、长度、与矢状面的夹角在男女之间的差异有统计学意义(P＜0.001). 结论 髋臼后柱可容纳7.3 mm的拉力螺钉,但男女的进针角度不同.螺钉的直径不能仅仅靠截骨面的直径确定.     

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.     

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.     

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.