不同种类液体急性等容血液稀释对脊柱手术患者血流动力学的影响和血液保护效应

目的观察不同种类液体急性等容血液稀释(ANH)对脊柱手术患者血流动力学的影响和血液保护效应。方法选择择期全麻下行后路脊柱手术的患者60例,男30例,女30例,年龄48~65岁,ASAⅠ或Ⅱ级,随机分为三组:ANH晶体组(A组)、ANH胶体组(B组)和对照组(C组),每组20例。A组和B组在俯卧位全麻下行ANH,目标Hct为32%,A组放血同时用3倍体积的复方乳酸钠稀释,B组放血同时用相同体积的羟乙基淀粉130/0.4氯化钠注射液稀释,C组不做ANH,为对照组。记录ANH前5 min(俯卧位后5 min,T0)、ANH结束后10 min(切皮前5 min,T1)、输血(包括异体血和自体血)前5min(T2)和输血结束后10min(T3)的MAP、HR、心脏指数(CI)、每搏量变异度(SVV)、Hb、Hct、Plt、凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)及BIS和体温;监测三组术中出血量、输血量(包括悬浮红细胞、血小板和新鲜冰冻血浆)、输注异体血患者例数、输液量及尿量。结果 T2、T3时A组MAP明显低于,SVV明显高于T0时和B、C组(P0.05);T1时A、B组CI明显高于T0时和C组(P0.05),T2、T3时B、C组CI明显高于T0时和A组(P0.05);T1、T3时A、B组Hb、Hct及Plt明显低于T0时(P0.05);T1、T2时A、B组Hb、Hct及Plt明显低于C组,T3时明显高于C组(P0.05);T2、T3时三组PT及APTT明显长于T0时,T3时A、B组PT及APTT明显短于C组(P0.05)。A、B组术中未输入悬浮红细胞,输入悬浮红细胞及输注异体血患者例数明显少于C组(P0.05);A组晶体液输入量明显多于B、C组,B组明显少于C组(P0.05);A、C组胶体液输入量明显少于B组(P0.05);A组尿量明显多于B、C组(P0.05)。三组术中出血量差异无统计学意义。结论 ANH可减少脊柱手术患者术中异体悬浮红细胞的输入量,有利于凝血功能的恢复,具有明显的血液保护效应;胶体液行ANH的扩容效果优于晶体液。     

不同稀释液等容量血液稀释对矫形外科手术患者肺水和氧合的影响

目的观察晶体或胶体等容量血液稀释(ANH)对矫形外科手术患者肺水及氧合的影响。方法 48例择期行髋关节置换术或椎管减压术患者,ASA Ⅰ或Ⅱ级,年龄18-70岁,体重55-79 kg,随机均分为3组:全晶组(Ⅰ组)、晶-胶混合组(Ⅱ组)和全胶组(Ⅲ组),每组16例。麻醉诱导后经桡动脉采血,采血量(ml)=体重(kg)×7．5×(基础Hct-目标Hct)/0．5×(基础Hct+目标Hct),目标Hct为0．28,同时经中心静脉补充等效量的晶体液或胶体液,Ⅰ组所采血量按3:1的比例补乳酸林格氏液;Ⅱ组所采血量一半由6％羟乙基淀粉按1:1补偿,另一半由乳酸林格氏液按3:1补偿;Ⅲ组所采血量均由6％羟乙基淀粉按1:1补偿。当术中出血占全身血容量20％时开始回输自体血。分别于麻醉诱导前即刻(基础值)、麻醉诱导后即刻、ANH后即刻、ANH后15 min、自体血回输前即刻、自体血回输后即刻测定Hct、血浆胶体渗透压、心脏指数(CI)、左室压上升最大速率(dp/drmax)、心率(HR)、脉搏血氧饱和度、平均动脉压(MAP)、中心静脉压(CVP)、肺血管外间质水(EVLW)和血浆胶体渗透压,并进行血气分析。结果各组术中MAP、脉搏血氧饱和度、HR、CVP等各项生命体征均平稳。与基础值比较,各组ANH后Hct均降低,CI、dp/dtmax降低,PaO2升高,ANH后Ⅰ、Ⅱ组血浆胶体渗透压降低(P< 0．05);Ⅱ、Ⅲ组ANH后血浆胶体渗透压高于Ⅰ组(P<0．05);组间及组内EVLW比较差异无统计学意义(P>0．05)。结论晶体液或胶体液ANH对矫形外科手术患者肺水和氧合无影响。     

不同程度急性等容量血液稀释对家兔血清S-100B蛋白浓度和脑氧代谢的影响

目的 探讨常温下不同程度急性等容量血液稀释(ANH)对家兔血清S-100B蛋白浓度和脑氧代谢的影响.方法 健康成年家兔32只,体重2～2.5 kg,随机分为4组(n=8),对照组(Ⅰ组)不行血液稀释;其余3组血液稀释的目标红细胞压积(Hot)分别为24%(Ⅱ组)、18%(Ⅲ组)、12%(Ⅳ组).麻醉下气管插管后行机械通气,维持体温37℃左右.左颈动脉和左颈内静脉穿刺并置管,用于监测血压、采血和血气分析.右颈内静脉穿刺并置管,用于监测中心静脉压.股动脉放血,同时Ⅱ组～Ⅳ组股静脉经30 min输注等量6%羟乙基淀粉200/0.5行ANH至目标Hct.于动脉、静脉穿刺并置管稳定20 min(To)、ANH后2、4、8 h(T1～T3)时,记录血液动力学指标;分别采集左颈动脉和左颈内静脉血样各0.1 ml,行血气分析,计算脑氧摄取率(CERO2);颈动脉取血样,采用ELISA法测定血清S-100B蛋白浓度.ANH后8 h时处死动物,取右侧脑组织,称湿重和干重,计算脑含水量.结果 与T0时比较,Ⅲ组T3时、Ⅳ组T1～T3时CERO2和血清S-100B蛋白浓度升高(P<0.05);Ⅰ组和Ⅱ组各时点CERO2和血清S-100B蛋白浓度比较差异无统计学意义(P>0.05);与Ⅰ组和Ⅱ组比较,Ⅲ组T3时、Ⅳ组T1～T3时CERO2和血清S-100B蛋白浓度升高(P<0.05);与Ⅲ组比较,Ⅳ组T1～T3时CERO2和血清S-100B蛋白浓度升高(P<0.05).各组问脑含水量比较差异无统计学意义(P>0.05).结论 常温下ANH目标Hct为24%时,对家兔脑氧代谢无影响;目标Hct≤18%时,发生脑氧代谢失衡和脑损伤.     

骨科手术患者急性高容量血液稀释-止血药-自体血回收联合应用的血液保护效果

目的 评价骨科手术患者急性高容量血液稀释(AHH)-止血药-自体血回收(IOBS)的血液保护效果.方法 择期骨科手术患者120例,性别不限,年龄18～64岁,ASA Ⅰ或Ⅱ级,预计术中出血量>800 ml,随机分为4组(n=30):AHH-IOBS-止血药组、IOBS-止血药组、 IOBS组和AHH-止血药组.AHH:气管插管后即刻至切皮前即刻,静脉输注6%羟乙基淀粉130/0.4溶液15 ml/kg,速率40 ml/min;IOBS:切皮前即刻行血液回收,血液洗出后即刻回输;止血药:切皮前10 min静脉注射血凝酶2 kU,同时肌肉注射1 kU.记录术中液体出入量、心率(HR)、平均动脉压(MAP)和中心静脉压(CVP),并采集静脉血样检测下列指标:血红蛋白浓度(Hb)、红细胞压积(Hct)、血小板计数(Plt)、凝血酶原时间(PT)、活化部分凝血酶原时间(APTT)和纤维蛋白原浓度(Fib).结果 与AHH-IOBS-止血药组比较,IOBS-止血药组CVP降低,Hb、Hct、Plt和Fib升高,AHH-IOBS组术中出血量增多,AHH-止血药组异体输血量增多和新鲜冰冻血浆使用免除率和异体输血免除率降低(P<0.05或0.01).结论 骨科手术患者AHH-IOBS-止血-联合应用的血液保护效应较好,安全性高.     

术中急性等容血液稀释对凝血功能的影响

目的观察非心脏外科手术患者应用急性等容血液稀释(ANHD)时凝血功能的变化。方法随机选择非心脏外科手术40例,ASAⅠ或Ⅱ级。麻醉后常温下行ANHD,稀释后30min(Hct28%,T1)后行手术,手术失血再稀释至Hct25%(T2)、Hct23%(T3),Hct降至23%时输自体血。于稀释前(T0)、T1、T2、T3及回输自体血后15min(T4)时测定各凝血功能参数。统计术中出血量及术后渗血量。结果T1~T3时PT明显延长(P<0.01),T4时有所改善,与T3时比,差异有统计学意义(P<0.01)。纤维蛋白原(FIB)T1~T3时与T0时比,明显降低(P<0.05或P<0.01),T4时有所回升,与T3时比,差异有统计学意义(P<0.01)。活化部分凝血活酶时间(APTT)渐延长,至T3时明显延长(P<0.01),T4时明显改善,与T3时比,差异有统计学意义(P<0.05)。血小板计数(Plt)亦渐减少,T1~T4时与T0时比,差异有统计学意义(P<0.05或P<0.01),T4时有所回升,与T3时比,差异无统计学意义。术中和术后出血无明显增多。结论非心脏外科手术病人应用中深度ANHD时,凝血功能降低,回输自体血后明显改善,术中和术后渗血量无明显增加。     

急性等容血液稀释自体输血在颅脑手术中的应用

目的探讨急性等容血液稀释(ANH)自体输血在颅脑手术中的临床应用价值。方法选取2018年6月至2020年6月期间在本院进行颅脑手术的62例患者进行研究。按照随机数表法分为对照组(31例)、研究组(31例)。对照组患者在颅脑手术中采用异体输血,研究组换患者在颅脑手术中采用ANH自体输血。对比分析两组患者在输血前及术后1小时的血流动力学指标[心率(HR)、中心静脉压(CVP)、收缩压(SBP)、舒张压(DBP)],血气分析指标[酸碱度(PH)、(PaCO2)、氧饱和度(SpO2)],血液稀释指标[血红蛋白(Hb)、红细胞比积(Hct)]及凝血指标[血小板(PLT)、活化部分凝血活酶时间(APTT)、血浆凝血酶原时间(PT)、纤维蛋白原(FIB)]的变化,并评估ANH自体输血的效果。结果输血前,研究组Hb、Hct水平明显低于对照组;手术后1小时,研究组Hb、Hct水平较输血前升高且明显高于对照组,差异有统计学意义(P0.05)。输血前,研究组PLT、APTT、FIB水平明显低于对照组,PT水平明显高于对照组,差异有统计学意义(P0.05);手术后1小时,研究组PT、FIB水平明显高于对照组,差异有统计学意义(P0.05);手术后1小时,两组PLT、APTT相比,差异无统计学意义(P0.05)。结论 ANH自体输血在颅脑手术中的临床应用,能降低对患者血流动力学、及凝血指标影响,有效帮助患者补充血容量。     

氨甲环酸不同给药模式用于经尿道前列腺电汽切除术

目的 探讨氨甲环酸不同给药模式对经尿道前列腺电汽切除术(TUVP)患者血液的保护.方法 选择ASA Ⅰ～Ⅲ级择期TUVP患者54例,随机双盲分为三组,A组:2 g氨甲环酸在患者手术开始用微泵20 ml/h静注;B组:1 g氨甲环酸在患者手术前静注,1 g氨甲环酸在患者手术开始用微泵10 ml/h静注;C组不用氨甲环酸.分别于术前(T0)、切皮后30 min(T1)、60 min(T2)、术毕(T3)、术后12 h(T4)采血测定Hct、Hb、Plt、平均血小板体积(MPV)、血小板粘附率(PAdT)及凝血活酶原时间(PT)、活化部分凝血活酶时间(APTT)、纤维蛋白原(FIB)、栓溶二聚体实验(D-dimer),记录手术时间和出血量.结果 C组手术时间最长,A组次之,B组最短(P<0.05).T3、T4时C组出血量最多,A组次之,B组最少(P<0.05).T3、T4时C组Hct最低,A组次之,B组最高(P<0.05).T1～T4时C组Plt、PAdT、MPV、FIB显著低于A、B组,且A组低于B组(P<0.05).T1～T3时C组AFTT、PT显著长于A、B组,且A组长于B组(P<0.05).T1～T4时C组D-dimer显著高于A、B组,且A组高于B组(P<0.05).结论 氨甲环酸明显减少TUVP患者出血,在保护血小板数目和功能方面发挥作用,负荷量氨甲环酸效果更好.     

肝移植术麻醉中自体血液回输技术的应用

目的 探讨肝移植术中应用自体血液同输技术的安伞性和效果.方法 选择行原化肝移植术患者46例,根据是否符合自体血回输标准分为两组:回输组和对照组,每组23例.回输组术中应用自体血液回收机进行血液收集、回输,观察其效果.分别于麻醉前、无肝前期、无肝期、新肝期、术毕等时点采血样,测定红细胞汁数(RBC)、血红蛋白(Hb)、血小板(Plt)、血细胞比容(Hct)、凝血酶原时间(PT)、活化部分凝血酶时间(APTT)、纤维蛋白原含量(FIB)及国际标准化比值(INR).结果 回输组每例回输自体血(2 613±1 637)ml,输入异体浓缩红细胞量显著少于对照组(P＜0.01),两组间各时点RBC、Hb,Plt、Hct、PT、APTT、FIB、INR差异无统计学意义.结论 肝移植术中应用自体血液叫输技术能及时回收失血,维持有效循环,显著减少异体血输入.     

止血环酸在心肺转流术中对凝血功能的影响

目的 应用sonoclot分析仪(SCT)观察止血环酸在心脏手术中的血液保护效果。方法36例心脏手术患者分成工组(抑肽酶,n=12)、Ⅱ组(止血环酸,n=12)和Ⅲ组(非用药组,n=12)。Ⅰ、Ⅱ组在心肺转流(CPB)下完成心脏手术,Ⅲ组则为非CPB下的冠脉搭桥手术。应用SCT观察切皮前和鱼精蛋白中和肝素后的凝血和血小板(Plt)功能的变化。结果 sonACT在T_1时点Ⅲ组为(123.21±18.58)s,明显高于Ⅰ组的(110.36±24.72)s和Ⅱ组的(106.09±13.91)s(P均<0.05);纤维蛋白凝集率(clot rate)、Plt功能在T_1与T_2时点三组之间均无显著差异。Plt在T_2时点Ⅲ组则明显高于Ⅰ、Ⅱ组。Ⅰ、Ⅱ组在T_2时点的Plt较T_1下降非常显著(P<0.01),Ⅲ组则无明显改变。结论 止血环酸对CPB下心脏手术患者凝血与Plt功能的影响与抑肽酶相似,非CPB下冠状动脉搭桥术对血液系统的影响明显减轻。     

急性等容血液稀释对老年肝癌病人围手术期凝血和纤溶功能的影响

目的 观察急性等容血液稀释（ANH）用于老年肝癌切除手术时对凝血和纤溶功能的影响。 方法 选择2007年2月至2008年2月在宁波大学医学院附属李惠利医院行肝脏肿瘤切除手术的老年病人30例,对其围手术期凝血和纤溶功能影响的临床资料进行分析。将30例随机等分为ANH组（A组）和对照组（B组）。 结果 两组病人围手术期出血量差异无统计学意义（P>0.05）,A组异体血需求量（350.0±70.7）mL比B组（457.0±181.3）mL明显减少（P<0.01）;两组在ANH 30min后凝血酶原时间（PT）、活化部分促凝血酶原激酶时间（APTT）值与麻醉诱导前比较显著延长,但仍在正常范围以内,A组回输自体血后指标得到一定改善;两组病人凝血指标凝血酶时间（TT）、D-二聚体（DD）组间比较差异无统计学意义（P>0.05）。两组病人围手术期的可溶性纤维蛋白单体复合物（SFMC）、凝血酶原片段1+2（F1+2）各时点组间比较差异无统计学意义（P>0.05）;与麻醉诱导前比较,A组病人ANH后30min 至术毕时间血小板膜糖蛋白（CD62P）表达明显低于B组（P<0.05）,两组各时点组内比较差异无统计学意义（P>0.05）。 结论 ANH对老年肝癌切除病人围手术期的纤溶和凝血功能无显著影响,并可明显减少异体输血。     

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.     

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.     

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.