生物电阻抗法评估维持性血液透析患者的容量状态与高血压的关系

目的:通过采用多频生物电阻抗技术(MBIA)分析维持性血液透析(MHD)患者容量状态与血压之间的关系,为临床治疗提供参考。方法:收集2019年03月—2019年10月在我院血液透析室接受血液透析超过6个月的患者97例,记录患者一般信息、实验室指标、生物电阻抗测量干体重前后1周内的平均家庭自测血压等资料,采用MBIA测量患者透析前总体液(TBW)、细胞外液(ECW)和细胞内液(ICW)、身高标化后的细胞外液量(nECW),根据家庭血压情况分为高血压组及血压正常组,比较两组患者的血清学指标、体液分布情况;分析MHD患者高血压的危险因素。结果:(1)透析前,高血压组与血压正常组比较发现,高血压组在ECW/TBW、iPTH高于血压正常组,差异有统计学意义(P<0.05);(2)高血压组与正常血压组单因素分析结果显示：两组患者间ECW/TBW(P=0.032)、iPTH(P=0.049),差异有统计学意义(P<0.05);(3)高血压组与正常血压组多因素分析结果显示：透析前ECW/TBW(OR=1.146,95%CI 1.010～1.300,P=0.034)、iPTH(OR=1.00...     

血液透析超滤脱水对细胞内外液的影响

目的了解血液透析对细胞内液(intracellular water,ICW)和细胞外液(extracellular water,ECW)的影响。方法选择2012年3月1日至2014年12月31日解放军空军总医院血液净化中心行维持性血液透析(maintenance hemodialysis,MHD)治疗的患者68例,应用整体多频生物电阻抗仪测定透析前和透析后1min内的ICW和ECW,比较血液透析后ICW和ECW的减少量(△ICW和△ECW),观察透析超滤脱水对ICW和ECW变化率(ⅤICW/ICW和△ECW/ECW)的影响。结果血液透析患者68例中,男性37例(占54.41%),平均身高(1.62±0.09)m,体质量指数(bodymnas8 index,BMI)为(23.43±3.13),透析前体质量为(64.72±10.65)kg,干体质量为(61.37±10.74)kg,超滤量为(2.78士0.97)L,透析后ICW/ECW值为(1.99:1)。MHD患者透析前后,ICW从(23.34±4.53)kg下降到(21.64±4.18)kg,差异有统计学意义(t=9.518,P0.01),ICW变化量△ICW=(1.70±1.47)kg;ECW从(12.02±2.41)kg下降到(10.91±2.20)kg,差异有统计学意义(t=10.726,P0.01),ECW变化量△ECW=(1.11±0.85)kg,两种体液变化率分别为△ICW/ICW(7.07%±5。16%)和@ECW/ECW(9.02%±5.80%)。该研究中透析后ICW/ECW=1.99:1,与应用同位素标记的金标准测得的结果 2.0:1高度一致,优于其他多数研究中的1.11:1。结论血液透析超滤脱水同时来源于ICW和ECW变化,并非主要来源于ECW;本方法可能是最为接近金标准的方法。     

应用生物电阻抗法评估维持性血液透析患者体液状况的探讨

目的探讨生物电阻抗法（bioeleetricalimpedanceanalysis,BIA）对维持性血液透析（MHD）患者体液状况的临床价值。方法选择行MHD的稳定患者93例（实验组）及健康志愿者109例（对照组）,并按性别分组。实验组按BIA检测时间分为血液透析前组（A组）、血液透析后组（B组）及下次血液透析前组（C组）。应用生物电阻抗仪,测算各组的细胞外液占体质量的百分比（ECV％）、细胞内液占体质量的百分比（ICV％）、身体水分总量占体质量的百分比（TBW％）、细胞外液／细胞内液（ECV／ICV）及浮肿指数（ECW／TBW）。比较各组间相关指标的差异。结果①在年龄相当时,女性体质量、身高均以实验组低。②对照组、A组、B组和3组之间的ECV％、ECV／ICV及ECW／TBW的差异均有统计学意义（P〈O．05）;无性别差异。实验组女性ICV％、TBW％大于对照组。③ECV％、ECV／ICV、ECW／TBW以B组最小。结论MHD患者存在营养不良,女性患者更常见。ECV％、ECV／ICV、ECW／TBW可作为监测MHD患者体液状况的指标。BIA在评估MHD患者体液状况方面值得进一步研究。     

人体成分测量在血液透析患者营养状态评价中的运用价值

目的:评价人体成分测量在血液透析患者营养状态评估中的运用价值。方法:选择2017年02月～2018年10月间我院血液净化中心透析龄大于3个月的维持性血液透析(maintenance hemodialysis,MHD)患者196例,采用多频生物电阻抗法(bioelectric impedance analysis,BIA)进行人体成分测量,内容包括:体质量指数(BMI),体脂比,瘦体重(体重-脂肪重量),水过多(Over Hydration,OH),干瘦体重(瘦体重-OH),细胞外液与总体水之比(ECW/TBW),结合血清营养指标评价患者营养状态。结果:两两比较显示:对MHD患者营养不良判断的评价,人体成分测量中的干瘦体重指标明显优于瘦体重指标及血清中白蛋白(Alb),前白蛋白(PAB),转铁蛋白(Tf)、胆固醇(TC)对患者营养不良的判断(P0.01);瘦体重指标对患者营养不良的判断优于血清中白蛋白,前白蛋白,转铁蛋白、胆固醇对营养不良的判断(P0.01)。Spearman相关分析结果显示:人体成分测量中的干瘦体重与BMI、体脂百分比呈正相关(r=0.294及r=0.183,P均0.05),与患者年龄、ECW/TBW及OH值呈负相关(r=-0.215,r=-0.198及r=-0.447,P均0.05);Logistic回归分析显示:干瘦体重、年龄、OH值为MHD患者营养不良的独立危险因素。结论:生物电阻抗技术较血清学对MHD患者营养不良的评估具有无创、经济、灵活等优点,可用于MHD患者早期营养不良的判断及指导临床对患者营养不良进行干预。     

应用生物电阻抗法评估维持性血液透析患者的容量状态与左心室肥厚及腹主动脉粥样硬化的关系

目的:应用生物电阻抗法分析维持性血液透析患者(maintenance hemodialysis,MHD)体内容量状态及与左心室肥厚、腹主动脉粥样硬化的关系。方法:选择上海市浦东新区人民医院MHD患者92例及健康对照组24例,应用生物电阻抗分析仪器测量实验组及对照组透析前身体骨矿物质含量,基础代谢率,计算患者体质量指数(boay mass index,BMI)、ECW/TBW,同时检验实验组血红蛋白(hemoglobin,Hb),前白蛋白(prealbumin,PA),白蛋白(albumin,alb),钙(calcium,Ca),磷(phosphorus,P),超敏C反应蛋白(high sensitivity C-reactive protein,hs-CRP),计算钙磷乘积(Ca×P),根据心脏彩超结果判断实验组是否有左心室肥厚,根据腹主动脉超声结果判断实验组是否有腹主动脉粥样硬化。对实验组和对照组容量情况进行统计对比,以ECW/TBW为容量指标,分析该指标与其他检测指标的相关性。结果:(1)实验组92例MHD患者中有原发病慢性肾小球肾炎14例,高血压肾损害16例,糖尿病肾病48例,Ig A肾病4例,尿酸性肾病2例,淀粉样肾损害2例,多囊肾4例,不明原因2例。经统计分析,实验组和对照组年龄、性别、ICW、ECW、TBW、BMI、骨矿物质含量、基础代谢率差异无统计学意义,对照组ECW/TBW水平明显低于实验组,差异有统计学意义(P 0. 05)。(2) ECW/TBW与Hb、PA、alb、Ca之间存在明显负相关,与hs-CRP、P之间存在明显正相关。(3)存在左心室肥厚的患者ECW/TBW高于非左心室肥厚患者,且ECW/TBW每增加一个单位,患者发生左心室肥厚的风险是原来的5. 363倍。(4)腹主动脉粥样硬化患者的ECW/TBW高于非腹主动脉粥样硬化患者,且ECW/TBW每增加一个单位,患者发生腹主动脉硬化的风险是原来的2. 902倍。结论:容量超负荷在维持性血液透析患者中普遍存在,且为血液透析患者左心室肥厚及腹主动脉粥样硬化的危险因素;容量负荷过重的患者营养状况更差,且可能存在微炎症状态。     

维持性透析患者透析后血压变异的危险因素研究

目的:探讨维持性透析(MHD)患者透析后6 h内血压变异增加的危险因素。方法:选择稳定透析患者123例,根据患者透析后6 h的血压的变异度(BPV)分为收缩压高变异组(HSBPV)及收缩压低变异组(LSBPV)、舒张压高变异组(HDBPV)及舒张压低变异组(LDBPV),分析患者血压变异度的影响因素。结果:透析后6 h患者SBPV为(12.56±2.38)%、DBPV为(12.60±3.04)%。在高收缩压变异组与低收缩压变异两组的年龄、干体重、单次透析超滤量、细胞外液(ECW)、细胞内液(ICW)、血红蛋白、i PTH、TC差异有统计学意义(P0.05),高舒张压变异组与低舒张压变异两组的年龄、干体重、单次透析超滤量、ECW、ICW、血红蛋白、i PTH、TC差异有统计学意义(P0.05)。干体重、ECW、血红蛋白、i PTH、TC是MHD患者透析后收缩压变异度的独立危险因素(P0.05),年龄、TC是MHD患者透析后舒张压变异度的独立危险因素(P0.05)。结论:透析前细胞外液高容量、低血红蛋白血症、高胆固醇血症、炎症状态及未得到控制的继发性甲旁亢可增加MHD患者透析后6 h的收缩压变异度;高龄、高胆固醇血症可增加MHD患者透析后8 h的舒张压的变异度。     

NT-proBNP联合BIA法对维持性血液透析患者容量超负荷及心功能损伤风险的预测作用

目的探讨N端脑钠肽前体(NT-proBNP)联合生物电阻抗法(BIA)对维持性血液透析(MHD)患者容量超负荷及心功能损伤的预测作用。 方法选取医院2018年1月至2020年1月收治的50例终末期肾脏病患者作为研究对象，研究设计为横断面研究，均实施MHD治疗。实施MHD前记录患者基线资料，MHD治疗结束前评估患者容量超负荷及心功能损伤状况。分析细胞内水分(ICW)、细胞外水分(ECW)、NT-proBNP对MHD患者容量超负荷及心功能损伤的预测价值。 结果50例MHD患者中：19例容量超负荷，31例容量负荷正常；7例心功能损伤，43例心功能正常。与容量负荷正常组相比，容量超负荷组的NT-proBNP、ECW升高，ICW降低(P<0.05)；与心功能正常组相比，心功能损伤组的NT-proBNP升高，ICW降低(P<0.05)。Logistics回归分析结果显示，ICW增高是MHD患者发生容量超负荷的保护因素(OR<1，P<0.05)，而ECW、NT-proBNP增高则是其危险因素(OR>1，P<0.05)；ICW增高是MHD患者发生心功能损伤的保护因素(OR<1，P<0.05)，而NT-proBNP增高是其危险因素(OR>1，P<0.05)。分析受试者工作曲线(ROC)发现，MHD患者治疗前NT-proBNP、ICW、ECW水平预测容量超负荷及心功能损伤发生风险的曲线下面积(AUC)均>0.70，提示其均有中等预测作用。 结论NT-proBNP联合BIA法对MHD患者容量超负荷及心功能损伤发生风险具有一定的预测作用。     

利用人体成分分析仪检测围手术期患者体液含量及分布变化的临床意义

目的通过人体成分分析仪检测患者围手术期的体液含量及分布变化,探讨体液含量及其变化在临床中的意义及应用价值。 方法本研究采用横断面研究方法,选择2016年3月至9月滨州医学院附属医院收治的患者123例,详细记录患者的临床资料,并进行人体成分分析检测。分析患者术前1 d与术后第1、3、5、7天细胞内液（ICW）、细胞外液（ECW）、总体液（TBW）的数据,观察术后ICW、ECW、TBW、ICW/TBW、ECW/TBW的变化。按照术后第1天ECW/TBW分组,分析患者术后第1天ECW/TBW的变化对白细胞、血红蛋白、白蛋白及临床预后的影响。 结果患者术后早期ICW、ECW、TBW均增加,随后逐渐下降至术前水平;术后第1天ICW/TBW达到最低,ECW/TBW达到最高,随后逐渐恢复至正常。术后第1天ECW/TBW比值越高（>0.400）的患者血红蛋白及白蛋白的水平越低,术后腹腔引流管的放置时间、术后住院时间越长,术后并发症的发生率及死亡率越高。 结论围手术期体液含量的检测对患者预后的评估、降低术后并发症具有重要的指导价值。人体成分分析仪是一种对围手术期患者的体液含量进行有效测量的工具,具有重要临床应用价值。     

生物电阻抗矢量法评估血液透析合并高血压患者的容量负荷

目的应用生物电阻抗矢量法评估血液透析合并高血压患者的容量负荷,探讨高容量负荷状态对高血压患者预后的影响。方法研究对象来自南京医科大学附属明基医院透析前收缩压(6次透析治疗前平均收缩压值)>160 mmHg的血液透析患者。用生物电阻抗矢量法评估患者容量状态,并根据患者容量状态分为容量增加组和非容量增加组(包括容量正常和容量下降的患者)。比较两组患者临床资料、实验室指标、细胞内液比例(ICW)、细胞外液比例(ECW)、体细胞质量、瘦体重、干瘦体重及其占总体重的百分比、脂肪含量占总体重的百分比、阻抗/身高、容抗/身高、相位角、疾病指数的差异。采用Kaplan⁃Meier生存曲线比较两组患者生存率的差异。结果共51例血液透析合并高血压患者入选本研究,容量增加组19例,非容量增加组32例(容量正常27例,容量下降5例)。容量增加组患者的血白蛋白、前白蛋白、血红蛋白、血细胞比容、血磷较非容量增加组显著下降,淋巴细胞比例明显升高,组间比较差异均有统计学意义(均P<0.05)。容量增加组的细胞外液比例、疾病指数显著高于非容量增加组(均P<0.01);相位角、阻抗/身高、容抗/身高显著低于非容量增加组(均P<0.01)。临床追踪20个月,容量增加组患者血压达标率(透析前收缩压<160 mmHg)低于非容量增加组(26.3%比43.8%),但差异无统计学意义。容量增加组患者全因死亡率高于非容量增加组(26.3%比15.6%),Kaplan⁃Meier生存曲线分析提示两组生存率的差异尚无统计学意义。结论容量负荷增加的血液透析合并高血压患者细胞外液增加明显,营养状态评估指标较非容量增加的高血压患者明显下降,而淋巴细胞比例升高,可能与患者微炎症状态有关。容量负荷增加的高血压患者血压更加难以控制,临床预后可能不及非容量增加的患者。     

通过人体成分分析比较老年和非老年血液透析患者的容量负荷和营养状况

目的评价老年和非老年维持性血液透析(MHD)患者的容量负荷和营养状况,并分析影响其液体超载和营养不良状况的相关危险因素。方法选择MHD患者101例,按年龄分为非老年组[65岁(n=51)]和老年组[≥65岁(n=50)]两组。应用人体成分分析仪(body composition monitor,BCM)、实验室指标及营养不良-炎症评分(malnutrition-inflammation score,MIS)评估两组患者的容量负荷和营养状况,并分析可能引起液体超载和营养不良状况的相关危险因素,应用Logistic回归方程分析液体超载和营养不良发生的独立危险因素。结果与非老年组MHD患者相比,老年组MHD患者白蛋白(P=0.006)、前白蛋白(P0.01)、体细胞质量(P=0.03)、握力(P0.05)均明显降低,细胞外液量(ECW)/总水量(TBW)显著增高(P0.01),营养不良发病率显著高于非老年组(P=0.004)。在MHD患者中,ECW/TBW、MIS评分与年龄呈正相关(P0.01),而握力(P0.01)、体细胞质量(P0.01)与年龄呈负相关。单因素分析表明,年龄(P0.01)、握力(P0.01)、体细胞质量(P0.01)与ECW/TBW有关;年龄(P=0.001)、性别(P=0.010)、白蛋白(P=0.001)、前白蛋白(P0.01)、握力(P0.01)、体细胞质量(P=0.003)与MIS评分有关。在多变量分析中,体细胞质量(P=0.001)的减少是增加ECW/TBW的独立危险因素,即影响液体超载的独立危险因素,而前白蛋白(P=0.029)是影响患者营养不良状况的独立危险因素。结论与非老年组的MHD患者相比,老年组患者的体液超载和营养不良状况更为普遍。体细胞质量是引起MHD患者体液超载状况的独立危险因素,前白蛋白是MHD患者营养不良的独立危险因素,因此,由BCM评估的体细胞质量可能是评估老年MHD患者容量负荷状态的一种临床有用的方法。临床可应用BCM与实验室指标相结合的方法对MHD患者的人体成分和营养状况进行实时监测。     

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.