急性等容血液稀释联合低中心静脉压对肝癌手术脑氧代谢的影响

目的观察急性等容血液稀释(ANH)联合低中心静脉压(LCVP)在肝癌手术中对患者脑氧代谢的影响。方法拟行肝癌手术患者40例,随机均分为两组。ANH+LCVP组全麻后先进行ANH,然后进行LCVP控制,在肝脏实质完全离断前CVP控制在0～5cmH2O,肝实质切除止血彻底后将CVP恢复至7～8cmH2O;常规治疗组手术中CVP维持在7～8cmH2O。分别于入室后(T0)、采血后5min(T1)、肝癌切除后5min(T2)、恢复容量后5min(T3)抽取动脉、颈内静脉球部的血作血气分析,检测动脉、颈内静脉血氧饱和度(SaO2、SjvO2)、动脉、颈内静脉血氧分压(PaO2、PjvO2)、Hb和Hct,并计算动脉、颈内静脉球部血氧含量(CaO2、CjvO2)、脑氧摄取率(CERO2)、动脉、颈内静脉球部血氧含量差(Da-jvO2)和乳酸差(VADL)。结果与T0时比较,T2、T3时两组Hb、Hct值明显降低(P<0.05),T1～T3时ANH+LCVP组SjvO2明显升高(P<0.05),CERO2、Da-jvO2明显降低(P<0.05),T2、T3时常规治疗组CERO2、Da-jvO2明显降低(P<0.05)。与T2时比较,T3时ANH+LCVP组Hb、Hct值明显升高(P<0.05),常规治疗组明显下降(P<0.05)。与常规治疗组比较,ANH+LCVP组T1、T2时Hb、Hct值明显降低、而T3时明显升高(P<0.05),T1～T3时SjvO2、T3时Da-jvO2明显升高(P<0.05);而T1时Da-jvO2明显降低(P<0.05)。结论急性等容血液稀释联合低中心静脉压技术可以安全应用于肝癌手术中,对脑氧代谢无明显不良影响。     

低水平呼气末正压通气对全身麻醉腹腔镜胃癌根治术患者脑血流动力学的影响

目的 观察呼气末正压通气对全身麻醉腹腔镜胃癌根治术患者脑血流动力学的影响.方法 择期行全身麻醉腹腔镜胃癌根治术的患者80例,美国麻醉医师协会(ASA)分级Ⅰ～Ⅱ级,采用随机数字表法分为A、B组,每组40例.A组通气参数:潮气量(VT)8ml/kg,呼吸频率(RR) 12次/分,呼气末正压(PEEP)5 cmH2O(1 cmH2O=0.098 kPa).B组通气参数:VT 8 ml/kg,RR 12次/分.于气腹前(T0)、气腹后30 min(T1)、气腹后1 h(T2)、气腹后2h(T3)时记录大脑中动脉平均血流速度(Vm)、平均动脉压(MAP)、心率(HR)、经皮测血氧饱和度(SpO2)、呼气末二氧化碳分压(PetCO2)变化,分别抽取各时点桡动脉血、颈内静脉球部血进行血气分析,记录动脉血氧分压(PaO2)、动脉血二氧化碳分压(PaCO2)、动脉血氧饱和度(SaO2)、血红蛋白(Hb)浓度;颈内静脉血氧分压(PjvO2)和颈内静脉血氧饱和度(SjvO2),根据Fick公式分别计算脑动脉和颈内静脉血氧含量(CjvO2)及其差值(Da-jvO2).结果 与气腹前比较,两组气腹后Vm、SjvO2、PaCO2在各时间点明显升高(P＜0.05).但是A组Vm、SjvO2、PaCO2的上升趋势较B组更为缓和,A组PaCO2在T1、T2分别为(35.5±2.7)、(40.7±3.5)mmHg,明显低于B组的(39.9±3.1)、(49.4±4.7)mmHg(P＜0.05),而Vm在T3为(68.9±8.1)cm/s,明显低于B组的(87.9 ±9.6) cm/s(P ＜0.05).与气腹前比较,气腹后2h两组Da-jvO2明显下降(P＜0.05),组间比较,A组下降幅度明显大于B组(P＜0.05).结论 低水平呼气末正压通气对全身麻醉腹腔镜胃癌根治术患者手术期间能有效降低术中的高二氧化碳血症,维持患者脑血流动力学的稳定,从而改善脑的过度灌注状态,改善患者的脑血流量和脑氧供需平衡.     

不同Narcotrend指数下老年患者全麻术中脑氧代谢的比较

目的比较不同Narcotrend指数(Narcotrend index,NTI)下老年患者全麻术中脑氧代谢的变化。方法择期行腹部手术(术式不限,手术时间短于2h)的老年患者90例,随机均分为A、B、C组,术中NTI分别维持在D0、D2和E1。分别采集麻醉诱导前(T0)、NTI达到预定值后10min(T1)、30min(T2)、关腹即刻(T3)和术毕时(T4)桡动脉及颈静脉球部血样行血气分析,记录并计算颈内静脉球部血氧含量(SjvO2)、桡动脉-颈内静脉球部血氧含量差(Da-jvO2)及乳酸差(VADL)、脑氧摄取率(CERO2)。结果 T1~T4时B和C组SjvO2明显高于,Da-jvO2、CERO2明显低于T0时和A组(P0.05);T1~T4时C组SjvO2明显高于B组(P0.05)。结论老年患者全麻术中NTI维持在D0、D2和E1时,脑氧代谢虽发生变化,但并未破坏大脑正常的氧供-氧耗平衡。     

腹腔镜结直肠癌根治术气腹及Trendelenburg体位对≥60岁患者脑血流的影响

目的探讨气腹及Trendelenburg体位对腹腔镜结直肠癌根治术≥60岁患者脑动脉血流的影响。方法 2014年6月~2015年9月100例限期腹腔镜结直肠癌根治术≥60岁患者,ASAⅠ~Ⅱ级,手术时间2 h,按照年龄分为2组,每组50例:60~70岁为A组,70岁以上为B组。应用经颅多普勒技术监测右侧大脑中动脉血流信号,分别于麻醉诱导前(T0)、气管插管后5 min(T1)、气腹完成后(T2)、调节头低脚高30°体位即刻(T3),调节体位后1 h(T4),调节体位后2 h(T5)以及停气腹恢复平卧位10 min(T6)记录收缩期峰流速(Vs)、平均流速(Vm)和搏动指数(PI),并同时记录患者各时间点平均动脉压(MAP)。结果 A组患者Vs在T4~T6时点分别为(73.1±10.8)、(73.5±9.9)、(77.5±10.9)cm/s,较T1时点(66.4±9.3)cm/s显著升高(P0.05);Vm在T3~T6时点分别为(55.3±7.9)、(54.5±9.2)、(57.3±10.1)、(68.9±9.9)cm/s,较T1时点(48.3±8.1)cm/s显著升高(P0.05)。B组Vs在T3~T6分别为(74.4±9.5)、(78.2±9.5)、(79.0±10.3)、(82.0±9.3)cm/s,均较T1时点(65.8±8.9)cm/s显著增高(P0.05);Vm在T2~T6分别为(55.2±7.6)、(59.3±9.5)、(59.2±8.7)、(61.6±10.2)、(67.6±8.8)cm/s均较T1时点(46.5±8.9)cm/s显著增高(P0.05)。B组在T2~T5时点Vs和Vm均显著高于A组(P0.05),在T3~T6时点PI显著高于A组(P0.05)。2组间各时点MAP无明显差异(P0.05)。结论腹腔镜结直肠癌根治术中Trendelenburg 30°体位使老年患者脑动脉血流增加,≥70岁患者较60~70岁患者脑血流受气腹及体位的影响更加明显。     

不同剂量尼莫地平对老年腹部手术患者术后认知功能和脑氧代谢的影响

目的 观察不同剂量尼莫地平对老年腹部手术患者术后认知功能和脑氧代谢的影响.方法 择期行腹部手术的老年患者120例,年龄65～83岁,ASA Ⅰ或Ⅱ级,随机均分为三组:Ⅰ组在全麻诱导插管后,持续输注尼莫地平15μg·kg-1·h-1至术毕;Ⅱ组输注尼莫地平7.5μg·kg-1·h-1至术毕;Ⅲ组输注等容量生理盐水.于术前1 d、术后4 d测定简易智力状态检查表(MMSE)评分,术后比术前减少2分或2分以上判为发生术后认知功能障碍(POCD).各组于麻醉诱导前(T0)、麻醉后60 min(T1)和术毕(T2)时,同步采取桡动脉和颈内静脉球部血标本行血气分析,计算动脉血氧含量(CaO2)、颈内静脉球部血氧含量(CjvO2)、动-颈内静脉血氧含量差(Da-jvO2)和脑氧摄取率(CERO2).结果 三组共22例术后4 d发生POCD,Ⅰ组5例(12.5%)、Ⅱ组8例(20.0%)、Ⅲ组9例(22.5%).Ⅰ组POCD发生率明显低于Ⅲ组(P＜0.05).T1、T2时Ⅰ组Da-jvO2和CERO2明显低于T0时和Ⅲ组(P＜0.01).T2时Ⅱ组Da-jvO2和CERO2明显低于T0时和Ⅲ组(P＜0.05).结论 尼莫地平15μg·kg-1·h-1能减少POCD的发生,可能与改善脑氧代谢有关.     

不同穿刺体位和头偏左转各角度对患者右颈内静脉B超影像的影响

目的研究不同穿刺体位和头偏左转各角度对患者右颈内静脉B超影像的影响。方法随机选择择期手术患者100例,ASAⅠ~Ⅲ级,男62例,女38例,年龄21~79岁。患者依次取去枕垫肩平卧位(肩下垫6cm薄枕)、平卧位、Trendelenburg体位(15°~30°头低足高位),分别将患者头偏左转0°、30°、45°和60°。超声探头置于患者右侧胸锁乳突肌三角的顶点,通过二维B超测量上述不同穿刺体位和头偏左转各角度时患者右颈内静脉的横径和横截面积等指标。计算右颈内静脉和颈总动脉重叠率和安全穿刺范围。结果与Trendelenburg位比较,头偏左转不同角度去枕垫肩平卧位和平卧位患者右颈内静脉横截面积明显减小(P<0.05),且去枕垫肩平卧位明显小于平卧位(P<0.05)。与头偏左转0°比较,头偏左转30°、45°和60°时三种体位右颈内静脉横截面积明显增加(P<0.05)。与Trendelenburg位比较,头偏左转不同角度去枕垫肩平卧位和平卧位患者安全穿刺范围明显减小(P<0.05)。头偏左转30°、45°和60°角度三种体位的安全穿刺范围依次减小(P<0.05)。与Trendelenburg比较,头偏左转不同角度去枕垫肩平卧位和平卧位患者动-静脉重叠程度评分明显降低(P<0.05),且去枕垫肩平卧位明显小于平卧位(P<0.05)。头偏左转30°、45°和60°时三种体位患者动-静脉重叠程度评分依次升高(P<0.05)。结论患者取Trendelenburg位是经右侧胸锁乳突肌三角顶点颈内静脉穿刺置管时理想的穿刺体位。头偏左转有利于右颈内静脉的充盈,但为了减少误穿动脉的风险,头偏左转角度以不超过30°为宜。     

超声引导下右侧星状神经节阻滞对腹腔镜胃癌根治术患者双侧脑血流的影响

目的观察超声引导下右侧星状神经节阻滞(stellate ganglion block, SGB)对腹腔镜下胃癌根治术患者双侧脑血流的影响。方法选择2017年8月至2019年2月择期行腹腔镜下胃癌根治术患者60例,男31例,女29例,年龄60~80岁,ASAⅡ或Ⅲ级,采用随机数字表法将患者随机分为两组,每组30例:SGB组(S组)和对照组(C组)。S组于麻醉诱导前在超声引导下行右侧SGB,注入0.375%罗哌卡因8 ml,C组注射等容量生理盐水。通过经颅多普勒超声(TCD)记录SGB前(T0)、SGB后5 min(T1)、30 min(T2)、60 min(T3)、手术结束(T4)时双侧大脑中动脉(MCA)平均血流速度(Vm),计算搏动指数(PI)和阻抗指数(RI),同时记录T0-T4时的MAP、HR和CVP。结果与T0时比较,T2-T4时C组双侧Vm、MAP明显降低,双侧PI和RI明显升高(P<0.05);T2-T4时S组双侧Vm明显明显降低(P<0.05),非阻滞侧PI和RI明显升高(P<0.05);T2时S组MAP明显降低(P<0.05)。T3、T4时C组MAP明显低于S组(P<0.05)。结论超声引导右侧星状神经节阻滞可以明显降低阻滞侧颅内动脉血管阻力,增加腹腔镜下胃癌根治术中颅内血流动力学的稳定性。     

瑞芬太尼用于颅脑手术控制性降压的研究

目的 观察瑞芬太尼用于颅脑手术控制性降压对血流动力学和脑氧代谢的影响.方法 择期行颅脑手术患者30例,ASA Ⅰ或Ⅱ级,随机均分为瑞芬太尼组(R组)和硝普钠组(N组).术中监测和记录手术前、降压前、达到目标血压0 rain(T0)、5 min(T1)、10 min(T2)、20 min(T3)、30min(T4)及停止降压5 min(T5)、10 min(T6)、30 min(T7)时的HR、MAP、CVP、P盯C02和spO2,并抽取桡动脉、右颈内静脉球部血标本测血气,计算麻醉后、手术前、降压前、达到目标血压10 min的颈内静脉球部血氧含量差(Da-jvO2)、脑氧代谢率(CERO2)、RPP.结果 R组各时点HR慢于N组(P<0.05).R组和N组的Da-jvO2、CERO2在降压时均下降(P<0.05),但两组差异无统计学意义.结论 瑞芬太尼用于颅脑手术控制性降压在改善脑氧代谢的同时不增快HR.     

N-乙酰半胱氨酸对心肺转流下心脏直视手术患者肺功能的影响

目的观察N-乙酰半胱氨酸(N-acetylcysteine,NAC)对心肺转流(cardiopulmonary bypass,CPB)下心脏直视手术患者肺功能参数的影响。方法择期在CPB下行心脏瓣膜置换术的风湿性心脏病患者40例,性别不限,年龄40~65岁,体重45~80kg,ASAⅡ或Ⅲ级,心功能Ⅰ~Ⅲ级,随机均分为NAC组和对照组(C组)。NAC组:麻醉诱导后CPB前静脉输注NAC 100mg/kg,CPB开始后静脉持续输注NAC 40mg/kg至术毕。C组:等剂量用生理盐水作为安慰剂静脉输注。于麻醉诱导后(T0)、开胸后CPB前(T1)、术毕关胸后(T2)、术后5h(T3)、24h(T4)和48h(T5)检测呼吸指数(RI)、氧合指数(OI)、肺泡-动脉氧分压差(A-aDO2)和气道阻力(R)。结果与T0时比较,T2~T4时两组患者RI、A-aDO2明显升高(P0.05)、OI明显降低(P0.05)、T2和T3时两组患者气道阻力明显升高(P0.05)。与C组比较,T2~T4时NAC组RI和A-aDO2明显降低(P0.05)、OI明显升高(P0.05)、T2和T3时NAC组气道阻力明显降低(P0.05)。结论 N-乙酰半胱氨酸可以减轻CPB导致的肺功能损伤,对肺脏可能具有保护作用。     

依托咪酯和异丙酚复合麻醉对腹部手术患者脑氧代谢影响的比较

目的 比较依托咪酯和异丙酚复合麻醉对腹部手术患者脑氧代谢的影响.方法 择期全麻下拟行腹部手术患者36例,ASA Ⅰ或Ⅱ级,随机分为异丙酚复合麻醉组(P组)和依托咪酯复合麻醉组(E组),每组18例.两组均静脉注射咪达唑仑0.08 mg/kg、芬太尼3μg/kg、维库溴铵0.1 mg/kg,P组静脉注射异丙酚1.5 mg/kg、E组静脉注射依托咪酯0.3 mg/kg行麻醉诱导,P组静脉输注异丙酚4～6mg·kg-1·h-1、E组静脉输注依托咪酯0.4～0.7 mg·kg-1·h-1,术中均间断注射维库溴铵和芬太尼维持麻醉.分别于麻醉前(T1)、气管插管后即刻(T2)、手术开始30 min(T3)及术毕即刻(T4)时监测HR、MAP和SpO2,抽取桡动脉血和颈内静脉球部血样行血气分析,测定乳酸浓度,计算动脉血氧含量(CaO2)、颈内静脉氧含量(cjvO2)、脑氧摄取率(CERO2).结果 两组HR、MAP和SpO2均在正常范围内.与T1时相比,两组SaO2、SjvO2、PaO2、PjvO2升高,T2-4时Da-jvO2和CERO2降低(P<0.01);两组问比较各时点SaO2、SjrO2、PaO2、PjvO2、CaO2、CjvO2、Da-jvO2、CERO2及乳酸水平差异均无统计学意义(P>0.05).结论 依托眯酯和异丙酚复合麻醉均可降低腹部手术患者的脑氧代谢率,且无明显差别.     

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.     

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.     

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.