右美托咪定对丙泊酚复合瑞芬太尼麻醉下脑功能区手术患者唤醒试验质量的影响

目的 评价右美托咪定对丙泊酚复合瑞芬太尼麻醉下脑功能区手术患者唤醒试验质量的影响.方法 拟行术中唤醒的脑功能区手术患者27例,性别不限,年龄17 ～ 43岁,BMI 20～ 24kg/m2,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将患者随机分为2组∶对照组(C组,n=13)和右美托咪定组(D组,n=14).麻醉诱导后气管插管,麻醉维持:2组均靶控输注丙泊酚和瑞芬太尼,丙泊酚血浆靶浓度3 ～5 μg/ml,调整丙泊酚血浆靶浓度维持BIS值55 ～ 65,瑞芬太尼效应室靶浓度2～6ng/ml.打开硬脑膜后,D组停止输注丙泊酚和瑞芬太尼,经15 min静脉输注右美托咪定负荷量0.3μg/kg,随后以0.2 μg-1·kg·h-1速率维持;C组打开硬脑膜后15 min将丙泊酚血浆靶浓度降至0.5μg/ml,将瑞芬太尼效应室靶浓度降至0.5 ng/ml.记录唤醒时间、唤醒试验期间心血管事件、头痛、躁动、谵妄和术中知晓等的发生情况.结果 所有患者均成功实施唤醒,并顺利完成手术.与C组比较,D组唤醒试验期间高血压、心动过速、头痛和术中知晓的发生率均降低(P＜0.05),唤醒时间差异无统计学意义(P＞0.05),2组未见躁动和谵妄的发生.结论 右美托咪定可提高丙泊酚复合瑞芬太尼麻醉下脑功能区手术患者唤醒试验的质量.     

右美托咪定对瑞芬太尼复合丙泊酚靶控输注全麻的影响

目的观察预先给予右美托咪定对瑞芬太尼复合丙泊酚靶控输注(TCI)全麻的影响。方法择期全麻行妇科腹腔镜手术患者40例,随机均分为右美托咪定组(D组)和对照组(C组),D组诱导前15min静脉泵注右美托咪定0.8μg/kg,C组则给予等量生理盐水。观察注药前(T1)、麻醉诱导前(T2)、插管前即刻(T3)、插管后即刻(T4)、插管后3min(T5)、拔管后即刻(T6)、拔管后3min(T7)的BIS、MAP、HR、肾上腺素(E)、去甲肾上腺素(NE)浓度变化;记录丙泊酚和瑞芬太尼的用量、麻醉恢复情况,随访术后延迟性呼吸抑制、术中知晓情况。结果 T2时D组BIS明显低于T1时和C组(P<0.01);与D组比较,T2、T4、T6时C组MAP明显升高,HR明显增快(P<0.05或P<0.01);T4、T6时C组的E、NE浓度明显高于T3时和D组(P<0.01),而D组则无明显变化;D组丙泊酚和瑞芬太尼的用量明显少于C组(P<0.05);D组拔管期间体动、呛咳的发生率明显低于C组(P<0.01),两组呼吸恢复时间、睁眼时间、拔管时间组间差异无统计学意义。结论瑞芬太尼复合丙泊酚靶控输注全麻预先静注右美托咪定0.8μg/kg可产生明显的镇静效应,有效抑制患者的应激反应,减少麻醉药的用量,且不延长麻醉恢复时间。     

不同剂量右美托咪定对丙泊酚诱导效应室靶浓度的影响

目的观察不同剂量右美托咪定在全麻患者气管插管时有效性和安全性及对丙泊酚效应室靶浓度(Ce)的影响。方法 60例全麻下行择期上腹部手术患者,随机均分为四组:D1、D2、D3、C组,分别在麻醉诱导前10min静脉泵注右美托咪定0.25μg/kg(D1组)、0.5μg/kg(D2组)和1.0μg/kg(D3组)及10ml生理盐水(C组)。麻醉诱导采用靶控输注丙泊酚,以BIS为靶控目标。丙泊酚初始Ce设为1.5μg/ml,递增梯度为0.5μg/ml,同时泵注瑞芬太尼0.2μg·kg-1·min-1。BIS≤60时推注罗库溴铵0.9mg/kg,BIS≤50并维持5s行气管插管。于输注右美托咪定前(T0)、诱导前(T1)、气管插管前(T2)、气管插管后1min(T3)、3min(T4)、5min(T5)、10min(T6)时记录SBP、DBP、HR、BIS、丙泊酚Ce。结果与T0时比较,T1时D2、D3组HR减慢、D3组SBP、DBP升高(P<0.05);与T1时比较,T2时D1组和C组SBP、DBP下降,HR减慢(P<0.05);与T2时比较,T3～T5时D1组和C组SBP、DBP升高,HR增快,T3时C组BIS升高(P<0.05)。T2～T6时丙泊酚CeD1、D2、D3组明显低于C组(P<0.05)。不同剂量右美托咪定各时点对丙泊酚Ce存在明显负相关关系。结论麻醉诱导前静脉输注不同剂量右美托咪定对丙泊酚诱导效应室浓度存在负相关关系。麻醉诱导前静脉输注右美托咪定0.5μg/kg心血管反应平稳并能显著减少诱导时所需丙泊酚Ce。     

熵指数指导下右美托咪定、丙泊酚及依托咪酯对脑功能区手术术中唤醒的影响

目的研究在熵指数指导下右美托咪定、丙泊酚及依托咪酯用于脑功能区手术术中唤醒的有效性及安全性。方法选择择期行脑功能区手术且需术中唤醒患者60例,随机分为右美托咪定组(D组)、丙泊酚组(P组)和依托咪酯组(E组),每组20例。手术过程中调整右美托咪定、丙泊酚或依托咪酯的泵注剂量使反应熵(RE)维持在40～60。记录唤醒时间、唤醒质量、唤醒期间不良反应的发生情况。结果 D组唤醒时间明显短于P、E两组(P0.05);D组唤醒质量明显优于P、E两组(P0.05),P组唤醒质量明显优于E组(P0.05)。D组不良反应总发生率明显低于P、E两组(P0.05)。结论在熵指数指导下,右美托咪定、丙泊酚和依托咪酯联合瑞芬太尼麻醉用于脑功能区手术术中唤醒均是安全且有效的,但右美托咪定的唤醒质量最高,唤醒期间不良反应发生率最低。     

不同剂量右美托咪定对丙泊酚复合瑞芬太尼用于整形外科手术患者麻醉效果的影响

目的 评价不同剂量右美托咪定对丙泊酚复合瑞芬太尼用于整形外科手术患者麻醉效果的影响.方法 择期行大面积皮肤瘢痕切除和进行皮瓣转移的手术患者60例,性别不限,年龄18～64岁,体重45 ～ 75 kg,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将患者分为3组(n=20):对照组(C组)、低剂量负荷量右美托咪定组(D1组)和高剂量负荷量右美托咪定组(D2组),D1组和D2组分别于麻醉诱导前10 min静脉输注右美托咪定0.6、1.0μg/kg负荷量,随后以0.4 μg· kg-1·h-1速率静脉输注至手术结束前30 min.麻醉诱导:靶控输注丙泊酚(血浆靶浓度4.0μg/ml)和瑞芬太尼(效应室靶浓度2.0 ng/ml),患者意识消失后静脉注射罗库溴铵0.6 mg/kg,气管插管后,机械通气,麻醉维持:靶控输注丙泊酚(血浆靶浓度2.0 ～ 3.5 μg/ml)和瑞芬太尼(效应室靶浓度1.5 ～ 2.5 ng/ml),维持Narcotrend指数为D级.分别于麻醉前、右美托咪定输注10 min、气管插管前即刻、气管插管后1 min、气管插管后5 min、停止输注右美托咪定、拔除气管导管前即刻、拔除气管导管后1 min、拔除气管导管后5min时记录Narcotrend指数、收缩压(SP)、舒张压(DP)和HR.记录麻醉诱导时间、丙泊酚和瑞芬太尼的用量,记录自主呼吸、定向力恢复和拔除气管导管的时间.拔除气管导管后10 min时行镇静-躁动评分,记录术中窦性心动过缓和麻醉恢复期不良事件的发生情况.结果 与C组比较,D1组和D2组丙泊酚、瑞芬太尼的总用量和拔除气管导管后10 min时镇静-躁动评分、麻醉恢复期恶心、呛咳和躁动的发生率降低,右美托咪定输注10 min时Narcotrend指数和HR降低,D2组麻醉诱导时间缩短(P＜0.05或0.01),D2组术中窦性心动过缓发生率高于C组和D1组(P＜0.05),3组间自主呼吸恢复时间、定向力恢复时间和拔除气管导管时间差异无统计学意义(P＞0.05).D1组和D2组气管插管前后和拔除气管导管前后SP、DP和HR差异无统计学意义(P＞0.05).结论 对于整形外科手术患者,麻醉诱导前静脉输注右美托咪定负荷量0.6 μg/kg,随后以0.4 μg·kg-1 ·h-1速率输注可缩短麻醉诱导时间,减少丙泊酚和瑞芬太尼用量,有效地抑制气管插管和拔除气管导管时的应激反应,降低了不良反应的发生.     

右美托咪定复合瑞芬太尼在纤维支气管镜引导下经鼻清醒气管插管中的应用

目的 观察右美托咪定复合瑞芬太尼用于困难气道患者纤维支气管镜引导下经鼻清醒气管插管中的安全性及有效性.方法 选择择期手术的困难气道患者40例,随机均分为:右美托咪定复合瑞芬太尼组(D组)和丙泊酚复合瑞芬太尼组(P组).D组给予右美托咪定1μg/kg静脉泵注15 min,同时给予瑞芬太尼0.5 μg/kg静脉泵注3 min;P组给予丙泊酚1.5 mg/kg静脉推注3 min和瑞芬太尼0.5 μg/kg静脉泵注3 min后纤支镜下经鼻插入气管导管.观察并比较两组患者入室时(T0)、给药前(T1)、给药后10 min(T2)、给药结束时(T3)、插管前(T4)、插管时(T5)、插管完成时(T6)、插管完成后1 min(T7)、5 min(T8)的HR、MAP、SpO2和RR;并记录患者插管过程中呛咳、恶心及躁动等不良反应和知晓情况.结果 与T0、T1时比较,T2～T8时两组HR、P组RR均明显减慢(P＜0.05);两组MAP、SpO2明显降低(P＜0.05).与P组比较,T2～T4、T8时D组HR明显减慢(P＜0.05);T2～T7时MAP明显升高(P＜0.05);T2、T3和Ts～T7时SpO2明显升高(P＜0.05);T2～T8时RR明显增快(P＜0.01).D组呛咳、恶心、躁动、插管知晓及SpO2下降发生率明显低于P组(P＜0.05).结论 右美托咪定复合瑞芬太尼或丙泊酚复合瑞芬太尼在纤维支气管镜引导下经鼻清醒气管插管都是安全有效的.与丙泊酚复合瑞芬太尼相比,右美托咪定复合瑞芬太尼可提供更稳定的血流动力学且不良反应发生率低.     

右美托咪定取代丙泊酚麻醉用于青少年脊柱侧凸手术的临床研究

目的 观察右美托咪定完全取代丙泊酚麻醉应用于青少年脊柱侧凸矫形手术对麻醉深度、唤醒试验、麻醉恢复及副反应的影响. 方法 择期行脊柱侧凸后路矫形手术患者60例,美国麻醉医师协会(ASA)分级Ⅰ或Ⅱ级,完全随机分组法分为两组,每组30例:右美托咪定组(Ⅰ组)采用右美托咪定负荷剂量1 μg/kg 10 min,继以0.25 μg·kg-1·h-1输注,丙泊酚组(Ⅱ组)采用丙泊酚起始100 μg· kg-1 ·min-1,两组均根据脑电双频指数(bispectral index,BIS)值调整使其维持在40～50,并配合使用瑞芬太尼0.4 μg· kg-1· min-1和顺式阿曲库铵1 μg· kg-1· min-1.术中以硝酸甘油进行控制性降压将平均动脉压(MAP)维持在60 mm Hg～70 mm Hg(1 mm Hg=0.133 kPa).肌肉分离完毕后停止使用顺式阿曲库铵,矫形完毕开始唤醒试验.记录两组术中唤醒时间和气管拔管时间及唤醒和苏醒时的Ramsay镇静评分、Riker躁动评分.记录Ⅰ组右美托咪定用量和两组有无术中知晓及恶心呕吐、寒战发生率. 结果 Ⅰ组术中唤醒和麻醉恢复时Riker评分[4.00(0.25)和4.00(1.00)]均低于Ⅱ组[4.50(1.00)和4.00(1.25)] (P＜0.05).两组Ramsay评分、唤醒时间、拔管时间、恶心呕吐和寒战发生率差异无统计学意义(P＞0.05).Ⅰ组右美托咪定用量为(2.4±0.5) μg· kg-1·h-1,Ⅱ组丙泊酚用量为(86±12) μg·kg-1· min-1.两组患者均未发生术中知晓. 结论 右美托咪定取代丙泊酚配合瑞芬太尼、硝酸甘油维持的全凭静脉麻醉在BIS监测下应用于青少年脊柱侧凸矫形手术镇静深度充分,可以优化术中唤醒和术后复苏质量且未增加副作用.     

右美托咪定对异体肾移植患者围术期肾功能的影响

目的研究右美托咪定对同种异体肾移植患者围术期肾功能的影响。方法选择行同种异体肾移植患者60例,男36例,女24例,年龄25~45岁,ASAⅡ或Ⅲ级,随机分为两组:右美托咪定组和对照组,每组30例。右美托咪定组麻醉诱导前给予右美托咪定1μg/kg泵注10min,随后以0.6μg·kg~(-1)·h~(-1)维持泵注至手术结束前30min;对照组以等容量生理盐水维持至手术结束前30min。记录两组患者在麻醉诱导前(T_1)、吻合血管开放前(T_2)、吻合血管开放后即刻(T_3)、吻合血管开放后30min(T_4)和手术结束后(T_5)的HR和SBP,于T_2、T_4、术后24h(T6)及术后48h(T7)采取静脉血检测血尿素氮(BUN)、血肌酐(Cr)、IL~(-1)8和半胱氨酸蛋白酶抑制剂C(Cys C)的浓度;记录术中液体输注量和尿量。结果 T_3时右美托咪定组HR明显慢于对照组;T_2、T_3时右美托咪定组SBP明显高于对照组(P0.05)。与T_2时比较,T6、T7时两组Cys C、BUN、Cr浓度明显降低,且T7时右美托咪定组Cys C浓度明显低于对照组(P0.05)。与T_2时比较,T6、T7时两组IL~(-1)8浓度明显降低,且右美托咪定组降低幅度明显大于对照组(P0.05)。右美托咪定组围术期尿量明显多于对照组(P0.05)。两组术中液体输注量差异无统计学意义。结论围术期应用右美托咪定可有效保护肾移植患者的肾功能。     

右美托咪定对脑电双频指数监测下丙泊酚闭环靶控系统稳定性的影响

目的探讨右美托咪定在腹腔镜手术中对脑电双频指数(BIS)监测下丙泊酚闭环靶控系统(closed-loop target controlled infusion,CL-TCI)稳定性的影响。方法选择择期腹腔镜手术女性患者60例,年龄20～60岁,BMI 18～28kg/m~2,ASAⅠ或Ⅱ级,随机分为右美托咪定组(D组)和生理盐水组(S组),每组30例。麻醉诱导前10min D组泵入右美托咪定1μg/kg,10min内注射完毕;完毕后改为0.3μg·kg~(-1)·h~(-1)持续注射,S组泵入等量生理盐水。诱导完成后均由CL-TCI泵注丙泊酚,具体给药剂量由靶控系统根据BIS值自动调节,BIS目标值为45。根据术中连续记录的BIS值计算总体分数(GS)、误差绝对中位数(MDAPE)、摆动度(Wobble)。记录丙泊酚、瑞芬太尼药物用量以及血管活性药物使用例次。结果D组GS、MDAPE均明显高于S组(P0.01),两组Wobble值差异无统计学意义;D组丙泊酚用量、麻黄碱使用次数明显少于S组(P0.01),两组瑞芬太尼的用量差异无统计学意义。结论腹腔镜手术患者全身麻醉过程中使用右美托咪定联合BIS监测下CL-TCI能明显减少丙泊酚的用量,但会降低该系统的稳定性。     

右美托咪定对全麻子宫切除术中血流动力学及应激反应的影响

目的探讨右美托咪定对全麻子宫切除术中血流动力学及应激反应的影响。方法择期行子宫切除术的患者40例,年龄42~58岁,随机均分为右美托咪定组(D组)和对照组(C组)。D组右美托咪定0.2mg用生理盐水稀释至50ml(4μg/ml),麻醉诱导前10min开始以10ml/h持续泵注到子宫标本切下为止,C组给予等容量生理盐水。采用咪达唑仑、舒芬太尼、顺式阿曲库铵、丙泊酚行麻醉诱导,气管插管控制呼吸。麻醉维持:静脉输注丙泊酚、瑞芬太尼,间断静注顺式阿曲库铵。记录给右美托咪定前(T0)、打开腹膜子宫操作开始时(T1)、子宫操作开始10min(T2)、20min(T3)、30min(T4)、子宫切下时(T5)和后腹膜缝合完毕时(T6)的SBP、DBP、HR和血浆肾上腺素、去甲肾上腺素和皮质醇浓度。结果 C组T1~T5时的SBP、DBP明显高于,HR明显快于T0时(P0.05),且SBP、DBP明显高于、HR明显快于D组(P0.05)。C组T1~T5时的肾上腺素、去甲肾上腺素和皮质醇浓度明显高于T0时(P0.05),且明显高于D组(P0.05)。结论右美托咪定用于全麻子宫切除术中,血流动力学稳定,可降低应激反应。     

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.