复合异丙酚麻醉时舒芬太尼抑制强直电刺激和切皮诱发胸腹部手术患者体动反应的药效学

目的 探讨复合异丙酚麻醉时舒芬太尼抑制强直电刺激和切皮诱发胸腹部手术患者体动反应的药效学.方法 择期胸腹部手术患者50例,年龄18～57岁,ASA分级Ⅰ或Ⅱ级,体重为标准体重的80%～120%,随机分为5组(n=10):舒芬太尼效应室靶浓度0.07、0.10、0.14、0.20和0.28 ng/ml组.靶控输注异丙酚,血浆靶浓度3.0～3.2 μg/ml,患者意识消失时各组按设定的效应室靶浓度靶控输注舒芬太尼,待效应室和血浆浓度达平衡后,给予强直电刺激(频率50 Hz,强度80 mA,波宽0.25ms),观察患者反应后给肌松药,行气管插管,维持上述异丙酚和舒芬太尼的靶浓度到切皮后4 min,试验观察结束.观察强直电刺激和切皮时患者的体动反应情况.采用通过概率单位回归分析法计算舒芬太尼抑制电刺激和切皮诱发的体动反应的半数有效效应室靶浓度(EC50)和EC95及其95%可信区间.结果 复合异丙酚麻醉时舒芬太尼抑制强直电刺激诱发的体动发应的EC50和EC95及其95%可信区间分别为0.12(0.09～0.14)ng/ml和0.20(0.17～0.31)ng/ml,抑制切皮诱发的体动发应的EC50和EC95分别为0.13(0.11～0.16)ng/ml和0.21(0.17～0.29)ng/ml;复合异丙酚麻醉时舒芬太尼抑制强直电刺激和切皮诱发的体动发应的EC50和EC95的比较差异无统计学意义(P＞0.05).结论 复合异丙酚麻醉时舒芬太尼抑制强直电刺激(频率50 Hz,强度80 mA,波宽0.25 ms)诱发的体动发应的EC50和EC95分别为0.12和0.20 ng/ml,抑制切皮诱发的体动发应的EC50和EC95分别为0.13和0.21 ng/ml,且抑制两组刺激诱发的体动发应的药效学无差异,提示强直电刺激可替代切皮用于评价麻醉药的药效学.     

复合异丙酚时舒芬太尼抑制置入输尿管镜时病人体动反应的半数有效效应室靶浓度

目的 确定复合异丙酚时舒芬太尼抑制置入输尿管镜时病人体动反应的半数有效效应室靶浓度(EC50).方法 择期行经尿道输尿管镜钬激光碎石术病人50例,性别不限,年龄20～60岁,BMI＜30 kg/m2,ASA分级Ⅰ级或Ⅱ级,随机分为不同舒芬太尼效应室靶浓度组(n=10),S1组、S2组、S3组、S4组和S5组舒芬太尼效应室靶浓度分别0.21、0.14、0.09、0.06、0.04 ng/ml.靶控输注异丙酚,血浆靶浓度2.5～3.0μg/ml,各组按相应效应室靶浓度靶控输注舒芬太尼,待病人意识消失且舒芬太尼达效应室浓度时置入输尿管镜,以进镜即刻至进镜后1 min内病人发生体动反应(咳嗽和吞咽动作除外)为阳性反应.采用Bliss法计算复合异丙酚时舒芬太尼抑制置入输尿管镜时病人体动反应的EC50为及其95%可信区间.结果 复合异丙酚时舒芬太尼抑制置入输尿管镜时病人体动反应的EC50为0.084 ng/ml,95%可信区间为0.066～0.107 ng/ml.结论复合异丙酚时,舒芬太尼抑制置入输尿管镜时病人体动反应的EC50为0.084 ng/ml.     

不同靶浓度舒芬太尼对异丙酚全麻患者脑电双频谱指数的影响

目的 评价不同靶浓度舒芬太尼对异丙酚全麻患者脑电双频谱指数(BIS)的影响.方法 择期全麻手术患者50例,ASA Ⅰ或Ⅱ级,年龄18～57岁,随机分为5组(n=10),舒芬太尼效应室靶浓度(Ce)分别设定为0.07、0.10、0.14、0.20、0.28 ng/ml.持续监测BIS、平均动脉压(MAP)、心率(HR)、脉搏血氧饱和度、呼气末二氧化碳分压和心电图.麻醉诱导:异丙酚起始血浆靶浓度(Cp)3.0μg/ml,若Ce与Cp平衡后5 min意识仍未消失,以0.3 μg/ml浓度梯度递增,持续靶控输注(TCI)异丙酚,患者意识消失时记录异丙酚Cp和Ce,并维持该浓度,随后按预设不同Ce TCI舒芬太尼,每分钟记录BIS、HR,收缩压(SP)、舒张压(DP)和MAP.待舒芬太尼Ce与Cp平衡时,静脉注射琥珀酰胆碱1.5mg/kg,行气管插管.结果 各组意识消失时异丙酚Cp、Ce及BIS差异无统计学意义(P>0.05);TCI舒芬太尼后,BIS逐渐降低,当舒芬太尼Cp和Ce平衡时,BIS明显低于TCI舒芬太尼前水平(P<0.05);BIS与舒芬太尼Ce呈负相关(r=-0.419,P<0.05).结论 靶控输注舒芬太尼可进一步降低异丙酚全麻患者的BIS.     

重症肌无力患者无肌松药下靶控输注丙泊酚时舒芬太尼诱导气管插管的半数有效浓度

目的 研究靶控输注(TCI)丙泊酚时舒芬太尼复合气管内表面麻醉,在无肌松药下诱导重症肌无力(MG)患者气管插管所需的半数有效浓度.方法 拟行经胸骨正中劈开胸腺切除术的MG患者20例,AsA Ⅰ或Ⅱ级.麻醉诱导丙泊酚采用血浆浓度(Cp)TCI,维持3.5μg/ml不变;舒芬太尼采用效应室浓度(Ce)TCI,按序贯法确定浓度,依次为0.15、0.23、0.34、0.50 ng/ml等比递增,相邻效应室靶浓度之间比例为1.5.复合气管内表面麻醉后行气管插管.监测诱导、插管过程中的血压,心率和脑电双频指数(BIS).结果 50%患者完成插管时舒芬太尼的浓度为0.23 ng/ml,95%的可信区间为0.20～0.27 ng/ml.结论 MG患者在不使用肌松药和复合气管内表面麻醉的情况下完成气管插管,丙泊酚血浆靶浓度为3.5 μg/ml,舒芬太尼半数有效效应室靶浓度为0.23 ng/ml.     

胸腹部手术患者靶控输注舒芬太尼复合异丙酚的药效学

目的研究复合靶控输注(TCI)异丙酚致患者意识消失时,胸腹部手术患者对切皮刺激无体动反应所需舒芬太尼效应室靶浓度的EC50和EC95。方法择期胸腹部手术患者50例,ASAⅠ或Ⅱ级,年龄18-57岁,随机分为5组(n=10),舒芬太尼效应室靶浓度分别设定为0．07、0．10、0．14、0．20、0．28 ng／ml。持续监测患者平均动脉压、心率、脉搏血氧饱和度、呼气末二氧化碳分压、心电图。麻醉诱导:起始血浆靶浓度(Cp)为3．0μg／ml,以0．3μg／ml为浓度梯度递增,持续TCI异丙酚致意识消失,并维持该浓度至试验结束,记录此时异丙酚的Cp和效应室靶浓度(Ce)。随后按预设的不同Ce持续TCI舒芬太尼,待效应室和血浆室浓度平衡后,静脉注射琥珀胆碱1．5 mg/kg,行气管插管。观察并记录切皮刺激时的体动反应和心血管反应,计算抑制切皮体动时舒芬太尼Ce的EC50和EC95。结果患者意识消失时各组间异丙酚的血浆和效应室靶浓度及给予琥珀胆碱后插管至切皮的时间比较差异无统计学意义(P>0．05);随着舒芬太尼Ce的增高,每组切皮刺激体动发生率依次降低,对切皮刺激无体动反应的舒芬太尼Ce的EC50为0．12 ng/ml,其95％可信区间为0．09-0．14 ng/ml,EC95为0．20 ng/ml,其95％可信区间为0．17-0．31 ng/ml。结论复合TCI异丙酚[Cp(3．1±0．3)μg/ml]致意识消失时,抑制胸腹部手术患者切皮反应的舒芬太尼Ce的EC50为0．12 ng/ml,EC95为0．20 ng／ml。     

复合异丙酚时不同靶浓度瑞芬太尼对神经外科手术患者脑电双频谱指数的影响

目的 探讨复合异丙酚时不同效应室靶浓度瑞芬太尼对神经外科手术患者脑电双频谱指数(BIS)的影响.方法 择期拟行额颞部开颅手术患者15例,年龄18～64岁,体重50～85 kg,ASA Ⅰ或Ⅱ级.先靶控输注异丙酚,效应室靶浓度为3μg/ml,效应室浓度达预设浓度后靶控输注瑞芬太尼,效应室靶浓度分别为2、3、4、5、6、7、8 ng/ml,效应室浓度依次达预设浓度时记录血压(BP)、平均动脉压(MAP)、心率(HR)和BIS.瑞芬太尼效应室浓度达5 ng/ml时行气管插管和机械通气,于气管插管前即刻和气管插管后即刻记录BP、MAP、HR和BIS.结果 与基础值比较,异丙酚效应室浓度3μG/ml 和瑞芬太尼不同效应室浓度时BIS降低(P<0.05或0.01);与异丙酚效应室浓度3μg/ml时比较,瑞芬太尼效应室浓度≥6 nG/Ml时BIS降低(P<0.05或0.01).结论 复合异丙酚时靶控输注瑞芬太尼效应室浓度≥6 ng/ml时可降低神经外科手术患者的BIS.     

复合异丙酚时舒芬太尼抑制维吾尔族患者气管插管心血管反应的半数有效效应室靶浓度

目的 确定复合异丙酚时舒芬太尼抑制维吾尔族患者气管插管心血管反应的半数有效效应室靶浓度(EC50).方法 全身麻醉下择期手术的维吾尔族患者31例,年龄21～59岁,性别不限,BMI 18～28 kg/m2,ASA分级Ⅰ或Ⅱ级.麻醉诱导:靶控输注异丙酚,效应室靶浓度为3.0 μg/ml,静脉注射顺阿曲库铵0.2 mg/kg,靶控输注舒芬太尼,第1例患者效应室靶浓度为0.8 ng/ml,待效应室靶浓度与血浆靶浓度达平衡后行气管插管,发生气管插管心血管反应时,则下一例患者采用高一级浓度,否则采用低一级浓度,浓度梯度的比值为1.1.发生气管插管心血管反应的标准:收缩压升高幅度超过基础值15％和(或)心率＞90次/min且持续时间＞15s.采用Probit概率回归法计算舒芬太尼抑制气管插管心血管反应的EC50及其95％可信区间.结果 复合异丙酚时舒芬太尼抑制维吾尔族患者气管插管心血管反应的EC50及其95％可信区间为0.46(0.43～0.49)ng/ml.结论 复合异丙酚时,舒芬太尼抑制维吾尔族患者气管插管心血管反应的EC50为0.46 ng/ml.     

丙泊酚麻醉下舒芬太尼抑制气管插管反应的半数有效浓度

目的探讨丙泊酚靶控输注(TCI)时舒芬太尼抑制气管插管反应的半数有效浓度(Ce50)。方法择期全麻手术患者29例,以效应室浓度TCI舒芬太尼,3 min后给予血浆靶浓度为3μg/ml丙泊酚,意识消失后给予维库溴铵0.1 mg/kg。舒芬太尼效应室靶浓度按序贯法确定,舒芬太尼靶控浓度从0.4 ng/ml开始,相邻靶浓度之间比率为1.2。结果丙泊酚3μg/ml麻醉下,舒芬太尼抑制气管插管反应的Ce50为0.32 ng/ml,95%可信区间(CI)为0.3～0.36 ng/ml。结论在复合TCI丙泊酚3μg/ml时,舒芬太尼抑制气管插管反应的Ce50为0.32 ng/ml。     

BIS和CSI监测不同效应室靶浓度异丙酚复合舒芬太尼患者镇静水平的准确性

目的 评价脑电双频谱指数(BIS)和麻醉深度指数(CSI)监测不同效应室靶浓度异丙酚复合舒芬太尼患者镇静水平的准确性.方法 外科手术患者90例,ASA Ⅰ或Ⅱ级,年龄20～49岁,体重45～70 kg,性别不限,随机分为6组(n=15):P1～3组分别靶控输注不同效应室靶浓度(2、4、6 μg/ml)异丙酚;SP1～3组分别靶控输注不同效应室靶浓度(2、4、6 μg/ml)异丙酚复合舒芬太尼.异丙酚初始效应室靶浓度为4 μg/ml,于气管插管后即刻,P1组和SP1组调整为2 μg/ml,P2组和SP2组调整为4 μg/ml,P3组和SP3组调整为6 μg/ml,20 min后SP1～3组经2～3 min静脉注射舒芬太尼0.7 μg/kg.于麻醉诱导前(T0)、气管插管前1 min(T1)、插管后30 s(T2)、15 min(T3)、30 min(T4)、35 min(T5)及40 min(T6)时记录HR、MAP、BIS和CSI.结果 P1～3组T3～6时组间比较BIS和CSI依次降低(P<0.05或0.01);SP1～3组T3～6时BIS和CSI组间比较依次降低(P<0.05);SP1组和SP2组T4～6时BIS和CSI分别较P1组和P2组降低(P<0.05或0.01);与P3组比较,SP3组T4～6时CSI降低(P<0.05),BIS差异无统计学意义(P0.05).结论 异丙酚效应室靶浓度2、4 μg/ml复合舒芬太尼时,CSI和BIS均可反映患者镇静水平;异丙酚效应室靶浓度6 μg/ml复合舒芬太尼时,仅CSI可反映患者镇静水平.     

人工流产术患者复合异丙酚时靶控输注瑞芬太尼的药效学

目的 探讨人工流产术患者复合异丙酚4.5 μg/ml时靶控输注瑞芬太尼的药效学.方法 拟行人工流产术患者135例,年龄18～30岁,ASAI级,孕6～10周.随机分为9组(n=15):瑞芬太尼效应室靶浓度分别为0.5、0.8、1.1、1.4、1.7、2.0、2.3、2.6和2.9 ng/ml(Ⅰ组～Ⅸ组).各组异丙酚效应室靶浓度均为4.5 μg/ml.采用概率单位回归分析法,计算麻醉效果达优时瑞芬太尼效应室靶浓度EC50、EC95及其95%可信区间(CI)和呼吸抑制时瑞芬太尼效应室靶浓度EC50、EC95及其95%CI.结果 麻醉效果达优时瑞芬太尼的效应室靶浓度EC50为1.67 ng/ml,其95%CI为1.45～1.90 ng/ml,EC95为3.88 ng/ml,其95%CI为3.08～5.89 ng/ml;呼吸抑制时瑞芬太尼效应室靶浓度EC50为2.44 ng/ml,其95%CI为2.28～2.64 ng/ml,EC95为3.36 ng/ml,其95%CI为2.99～4.34 ng/ml.麻醉效果达优时瑞芬太尼的效应室靶浓度EC95高于呼吸抑制时效应室靶浓度EC95(P＜0.05).结论 人工流产术患者复合异丙酚4.5 μg/ml时,麻醉效果达优时瑞芬太尼的效应室靶浓度EC50、EC95,分别为1.67、3.88 ng/ml,呼吸抑制时瑞芬太尼的效应室靶浓度EC50、EC95,分别为2.44、3.36 ng/ml.     

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.