1,6-二磷酸果糖对心肺转流期间氧代谢的影响

目的研究1,6-二磷酸果糖(FDP)对心肺转流(CPB)手术期间氧代谢的影响。方法随机将24例CPB手术病人均分成研究组(A组)和对照组(B组)。A组于转机前静滴FDP200mg/kg,B组于转机前滴入等量生理盐水,观察麻醉后(T1)、CPB前(T2)、升主动脉开放后10min(T3)、停CPB后10min(T4)、停CPB后60min(T5)的氧供(DO2)、氧耗(VO2)、氧摄取率(ERO2)及动脉血乳酸(ABL)的变化。结果两组T3时DO2明显降低(P<0.05),T3时A组ERO2和B组VO2、ERO2及两组T4、T5时VO2、ERO2明显增加(P<0.05或P<0.01),T3、T4和T5时ABL明显增加(P<0.01);B组T3、T4和T5时VO2、ERO2、ABL明显高于A组(P<0.05)。结论FDP对改善CPB手术期间氧供需平衡障碍有明显作用。     

不同阿片类药物对婴幼儿紫绀型先天性心脏病氧供氧耗的影响

目的 比较舒芬太尼和芬太尼对紫绀型心脏病婴幼儿氧代谢的影响.方法 紫绀型先天性心脏病患儿48例,随机均分为舒芬太尼和芬太尼两组,分别采用以舒芬太尼1 μg/kg诱导,2～3μg·kg-1·h-1维持(S组)为主和芬太尼10μg/kg诱导,20～30 μg·kg-1·h-1维持为主(F组)麻醉.分别于术前(T1)、心肺转流(CPB)结束后(T2)、术后4 h(T3)和术后24 h(T4)测定心排血量(CO)、混合静脉氧饱和度(SvO2)、混合静脉氧含量(CvO2),并计算出心排指数(CI)、氧供指数(DO2I)、氧耗指数(VO2I)、氧摄取率(ERO2),测定动脉血乳酸(Lac)含量.结果 与T1时比较,两组T2、T3时VO2 I显著升高(P<0.05),同时T2时DO2I升高、ERO2明显增加(P<0.05或P<0.01).S组VO2UI及ERO2的升高幅度小于F组(P<0.05).F组T3、T4时CI及DO2I明显低于S组(P<0.05).T2、T3时两组Lac均较T1时升高(P<0.01),T3、T4时F组较S组升高明显(P<0.05).两组SvO2均有下降趋势.结论 舒芬太尼复合麻醉可改善紫绀型先天性心脏病患儿术后氧代谢障碍.     

温度对体外循环期间氧代谢的影响

目的　观察温度对体外循环心肺转流 (CPB)期间氧代谢的影响。方法　成年健康杂种犬 11只 ,随机分为低温组 (H组 ,n =5 )和常温组 (N组 ,n =6)。H组采用 4℃改良托马氏停搏液间断灌注 ,最低鼻咽温度 2 8～ 3 0℃ ;N组采用氧合温血持续灌注 ,最低鼻咽温度 3 5 3～ 3 7 1℃。主动脉阻断 60分钟、CPB90分钟。分别测定麻醉稳定后CPB前、CPB3 0分钟、CPB90分钟、CPB后 60分钟时的动脉血氧饱和度 (SaO2 )、动脉氧分压 (PaO2 )、混合静脉血氧饱和度 (S vO2 )、混合静脉血氧分压(P vO2 )、血红蛋白浓度 (Hb)、红细胞压积 (Hct)、股静脉乳酸 (La)浓度 ,并计算氧供给 (DO2 )、氧消耗(VO2 )、氧摄取率 (ERO2 )。结果　与CPB前相比 ,CPB中两组的DO2 明显降低 (P <0 0 1) ,CPB后60分钟两组SaO2 、PaO2 、S vO2 都有不同程度的降低 (P <0 0 5或P <0 0 1) ,La、ERO2 增高 ;CPB过程中H组DO2 、VO2 低于N组 (P <0 0 5或P <0 0 1)。结论　在过度血液稀释情况下 ,常温和低温CPB后都存在低氧血症 ,但常温CPB期间氧利用明显优于低温CPB。     

原位肝移植患者术中氧代谢的变化

目的观察非静脉-静脉转流原位肝移植术患者术中全身氧代谢变化。方法23例接受非静脉-静脉转流原位肝移植的终末期肝病患者,全麻诱导用咪唑安定、依托咪酯、芬太尼和阿曲库铵,以异氟醚、丙泊酚、阿曲库铵、间断静注芬太尼维持麻醉,通过左侧桡动脉置动脉导管和右颈内静脉置Swan-Ganz导管。分别在麻醉后手术开始前(T1)、无肝期前10min(T2)、无肝期30min(T3)、新肝期30min(T4)及术毕(T5)采动脉血和混合静脉血,监测和计算以上各时点的SaO2、PaO2、SV-O2、心脏指数(CI)、氧供(DO2)、氧耗(VO2)和氧摄取率(ERO2)。结果与T1时相比,T2时S-VO2增加(P<0.05),DO2和VO2无明显变化,而ERO2下降。在T3时DO2和VO2下降明显(P<0.01),而ERO2则提高(P<0.05)。在T4时DO2、VO2和ERO2恢复至T1水平。至术毕时与无肝期无明显变化。结论非静脉-静脉转流下经典原位肝移植术患者术中氧代谢存在严重异常,以无肝期最为严重,氧供和氧耗明显下降,氧摄取率增加。     

胸段硬膜外麻醉复合全麻对开胸单肺通气患者氧代谢的影响

目的 通过比较吸入全身麻醉和吸入全麻复合胸段硬膜外麻醉对开胸手术的血液动力学和血气分析的变化,探讨硬膜外麻醉对全身氧代谢的影响。方法 20例因食管癌需开胸单肺通气手术患者,根据麻醉方法的不同随机分为异氟醚吸入全麻组(GI组)和异氟醚吸入复合硬膜外组(GIE组)。每组各10例。GI组采用异氟醚/芬太尼/维库溴铵麻醉。GIE组采用异氟醚/维库溴铵/胸部硬膜外0.5％罗哌卡因麻醉。连续监测平均动脉压(MAP)、心排指数(CI)、心率(HR)、中心静脉压(CVP)、外周血管阻力(SVRI)。分别于清醒时,侧卧双肺通气30 min,单肺通气15、30、60和120 min,侧卧再次双肺通气30 min抽取动脉,混合静脉血血样,测定血气,并计算氧供(DO2)、氧耗(VO2),以及氧供氧耗比(DO2/VO2)。结果 GIE组MAP低于GI组(P<0.05),SVRI不但低于GI组,也低于基础值(p<0.05)。单肺通气后30、60、120 min两组CI均高于基础值(P<0.05),GIE组各时间点CI与GI组比较差异无显著性(P>0.05)。两组各时间点DO2差异无显著性(P>0.05)。单肺通气15、30和60min时GIE组SvO2明显低于GI组(P<0.05),而VO2明显高于GI组(P<0.05),同时DO2/VO2明显低于GI组(P<0.05)。结论 以单纯全麻相比,胸段硬膜外联合全麻可能会使单肺通气早期全身氧耗增加,DO2/VO2降低。     

坐位神经外科手术期间血流动力学及氧代谢变化

目的　观测神经外科手术中坐位全身麻醉对体循环血流动力学及全身氧代射的影响。方法　 2 8例后颅窝及后颈髓手术病人 ,采用静脉复合诱导、吸入七氟醚或安氟醚及伍用芬太尼维持麻醉 ,以Swan Ganz导管、动脉和混合静脉血气监测及Fick方法测定血流动力学和氧代谢参数 ,包括CI、RAP、PCWP、SVRI、pHa、PaCO2 、PvCO2 、PaO2 、SvO2 、Hct、T、DO2 、及VO2 等。分别在麻醉前、坐位前、坐位后、坐位 6 0分钟、坐位 12 0分钟及术毕平卧位等时间点进行测定。结果　麻醉诱导后及坐位手术期间CI一直呈降低并维持在正常值的低限 (P <0 0 0 1) ,RAP略增加 ,MAP略下降 ,而SVRI呈持续增高 (P <0 0 0 1)。此期间DO2 和VO2 显著减少 (P <0 0 5～ 0 0 0 1) ,但PaCO2 、PvCO2 、pHa、及HCO-3 等参数均未见明显改变。术毕平卧后虽然CI、SVRI、T、Hct、DO2 、VO2 及PaCO2 等恢复或维持至麻醉前水平 ,但pHa和BE B呈有意义的下降、PvCO2 呈有意义的增高 (P <0 0 5 )。结论　神经外科病人在坐位全麻手术期间只要维持血流动力学平稳 ,机体全身氧代谢可得到维持 ,但在麻醉苏醒期有易发生氧代谢异常的倾向。     

脊柱内固定术患者自体血液回收-回输后氧代谢的变化

目的评价自体血液回收-回输对脊柱内固定术患者氧代谢的影响。方法40例行脊柱内固定手术病人随机分为两组:自体血液回收-回输组(A组,n=20);等量异体血液输入组(B组,n=20)。分别在麻醉前、输入自体血或等量异体血后、术毕时及术后1d,采集血液动力学和血气分析数据,计算心脏指数(CI)、氧供(DO2)、氧耗(VO2)、氧摄取率(ERO2),并测定血液乳酸(LA)浓度。结果与麻醉前相比,两组输血后、术毕时DO2升高(P<0.05),其他指标各时点差异无统计学意义(P>0.05)。与B组比较,术毕时A组ERO2降低(P<0.05),在各时点DO2、VO2差异无统计学意义,LA差异也无统计学意义,且数值均在正常范围内。结论自体血液回收技术在一定的出血范围之内,可以满足脊柱内固定术患者机体氧代谢的需求。     

肝移植术后患者并发急性肺损伤与术中氧代谢的关系

目的 研究肝移植术后患者并发急性肺损伤(ALI)与术中氧代谢的关系.方法 择期行肝移植术的终末期肝病患者62例,年龄29～63岁,体重48～76 kg,ASA Ⅲ或Ⅳ级.于麻醉诱导后(T1)、无肝期前10 min(T2)、无肝期25 min(T3)、新肝期30 min(T4)及术毕(T5)时,采集桡动脉血和混合静脉血进行血气分析,计算动脉血氧含量(CaO2)、混合静脉血氧含量(C(v)O2)、动脉-混合静脉血氧含量差(Ca-(v)O2)、氧供指数(DO2I)、氧耗指数(VO2I)、氧摄取率(ERO2)和通气.血流灌注指数(VQI).根据术后14 d内是否发生ALI分为2组:ALI组和非ALI组.两组氧代谢指标与术后ALI发生与否进行logistic回归分析.结果 与T1时相比,T2,4,5时P(v)O2升高,T3时降低,T2-5时CaO2、C(v)O2升高,T3时Ca-(v)O2升高,T2,4,5时DO2I、VO2I升高,ERO2降低,T3时VQI降低,氧合指数T3时降低,T4时升高(P<0.05).与非ALI组相比,ALI组T4,5时CaO2、C(v)O2和DO2I降低,T1,2,4,5时PaO2降低(P＜0.05).logistic回归分析结果示T4时PaO2和T5时CaO2与术后发生ALI有关(P<0.05).结论 肝移植术后患者并发ALI可能与新肝期氧代谢异常有关.     

两种麻醉方式下上腹部手术患者围术期能量代谢和呼吸氧价变化的比较

目的 观察两种麻醉方式下上腹部手术患者围术期能量代谢和呼吸氧价的变化,并探讨其机制。方法选择择期行上腹部手术患者40例,ASAⅡ级,年龄42-61岁,体重42-75kg。随机分为两组,每组20例,Ⅰ组采用硬膜外阻滞复合全身麻醉,Ⅱ组采用全凭静脉复合麻醉。用代谢监测仪分别于麻醉前、麻醉手术中和麻醉清醒后进行代谢测定。结果 两组患者麻醉后手术中的氧耗量(VO2)、二氧化碳产生量(VCO2)、能量消耗(EE)均低于麻醉前,而呼吸商(RQ)高于麻醉前(P<0.05);Ⅰ组患者手术后VO2、VC2、EE、RQ的变化无统计学意义(P>0.05);Ⅱ组患者手术后VO2、VCO2、EE均高于麻醉前(P<0.05),RQ明显低于麻醉前(P<0.05),与Ⅰ组比较,Ⅱ组患者术后VO2、VCO2、EE均升高,RQ降低(P<0.05);Ⅱ组患者呼吸氧价明显高于Ⅰ组患者(P<0.05)。结论 与全凭静脉麻醉比较,硬膜外阻滞复合全麻能够减少术后的能量代谢,降低呼吸氧价。     

舒芬太尼对重症先天性心脏病患儿体外循环后氧代谢的影响

目的 评价舒芬太尼对重症先天性心脏病患儿体外循环(CPB)后氧代谢的影响.方法 择期在CPB下行心脏畸形根治术的重症先天性心脏病患儿34例,ASA Ⅲ级,年龄5～35月,体重5～15 kg,随机分为2组(n=17):芬太尼组(F组)和舒芬太尼组(S组).麻醉诱导:静脉注射咪达唑仑0.2 mg/kg、哌库溴铵0.2 mg/kg,F组静脉注射芬太尼10μg/kg,S组静脉注射舒芬太尼1μg/kg,气管插管后机械通气.麻醉维持:间断静脉注射咪达唑仑0.5～1 mg/kg、哌库溴铵0.2～0.5 mg/kg,F组静脉输注芬太尼20～30μg·kg-1·h-1,S组静脉输注舒芬太尼2～3 μg·kg-1·h-1.于CPB结束后15 min(T1)、术毕(T2)和术后24 h(T3)时,测定心排血量,计算心脏指数(CI),并取肺动脉血样,测定混合静脉血氧含量(C(v)O2);取桡动脉血样测定动脉血氧含量(CaO2),计算氧供指数(DO2I)、氧耗指数(VO2I)和氧摄取率(ERO2).结果 与F组比较,S组T2,3时DO,I和CI升高,各时点ERO2降低(P<0:05),VO2I差异无统计学意义(P>0.05).与T1时比较,F组T2,3时CI降低(P<0.05或0.01),其余指标各时点差异无统计学意义(P>0.05);S组各指标各时点差异无统计学意义(P>0.05).结论 舒芬太尼可改善重症先天性心脏病患儿CPB后机体氧代谢,维持氧供和氧耗平衡,其效果优于芬太尼.     

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.     

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.     

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.