低流量N_2O-O_2单肺麻醉对动脉血气的影响

目的　探讨低流量N2 O O2 单肺麻醉对开胸病人动脉血气的影响。方法　 2 5例ASAⅠ～Ⅱ级开胸病人随机分为两组 :Ⅰ组 (n =10 )为对照组 ,采用硬膜外 +单肺通气麻醉 ;Ⅱ组 (n =15 )为观察组 ,采用低流量N2 O O2 单肺麻醉。观察两组开胸后单肺通气 1小时的吸入气氧分量(FIO2 )、PETCO2 、PaO2 、PaCO2 、动脉血氧饱和度 (SaO2 )、pH、肺泡与动脉血氧分压差 (PA aO2 )、动脉血与呼气末二氧化碳分压差 (Pa ETCO2 )变化。结果　Ⅰ组血气参数变化较小 ,无缺O2 和CO2 蓄积危险。Ⅱ组PaO2 和SaO2 明显下降 ,CO2 有蓄积 ,pH值降低 ,但PaO2 、SaO2 和pH仍在正常范围 ,CO2蓄积较轻 ,恢复双肺通气后即可恢复正常。结论　低流量N2 O O2 单肺麻醉发生缺O2 和CO2 蓄积的危险性有所增加 ,应加强监测。     

小潮气量联合PEEP对单肺通气时胸外科手术患者血管外肺水的影响

目的 探讨小潮气量联合呼气末正压(PEEP)对单肺通气时胸外科手术患者血管外肺水的影响.方法 食道癌手术患者40例,年龄45～80岁,体重48～83kg,性别不限,ASA分级Ⅰ或Ⅱ级,随机分为2组(n=20):传统模式单肺通气组(Ⅰ组)机械通气模式为间歇正压通气(IPPV),VT9 ml/kg,通气频率12次/min;小潮气量联合PEEP单肺通气组(Ⅱ组)机械通气模式为IPPV联合PEEP5 cm H2O,VT6 ml/kg,通气频率15次/min.于麻醉诱导前(T0)、双肺通气30 min(T1)、单肺通气30 min(T2)、单肺通气1 h(T3)、恢复双肺通气拔管前(T4)和术后18 h(T5)时,记录血管外肺水(EVLW)、血管外肺水指数(EVLWI)、肺血管通透性指数(PVPI)和心输出量(CO),于T1～4时记录气道峰压(Ppeak);取股动脉血样,进行血气分析,并计算氧合指数(OI).结果 与Ⅰ组比较,Ⅱ组单肺通气期间EVLWI和.PVPI升高(P＜0.05),其余指标比较差异无统计学意义(P＞0.05);两组各时点OI、CO和Poeak比较差异无统计学意义(P＞0.05);与T0时比较,Ⅰ组T1时PVPI升高(P＜0.05),其余时点PVPI、EVLW和EVLWI差异无统计学意义(P＞0.05),Ⅱ组T2时EVLW、T1～4时EVLWI和T1.2时PVPI升高(P＜0.05);与T1时比较,Ⅰ组T2～5时EVLW、EVLWI和PVPI差异无统计学意义,Ⅱ组T5时PVPI降低(P＜0.05).结论 采用VT6 ml/kg、PEEP 5 cm H2O的单肺通气可增加患者血管外肺水,未对肺功能产生有利作用.     

肺泡征募对单肺通气时氧合和肺内分流的影响

目的探讨肺泡征募(ARS)通气方式对单肺通气(OLV)时氧合和肺内分流的影响。方法择期行食管癌根治术患者24例随机分为观察组和对照组。全麻诱导后插入右双腔支气管导管,开胸后行OLV。观察组ARS于开胸后15min进行。记录动脉血压、HR和SpO2,并在侧卧后双肺通气(TLV)15min、OLV15min、OLV40min行动脉血气分析,以简化肺内分流公式计算肺内分流率(Qs/Qt)值。结果TLV15min和OLV15min时,观察组和对照组的SpO2、SaO2、PaO2、Qs/Qt和PaCO2差异无显著意义(P>0.05)。OLV40minARS观察组较对照组PaO2显著增加(P<0.05),Qs/Qt明显降低(P<0.05)。结论ARS通气方式在麻醉状态下OLV时可改善肺内氧合,降低肺内分流。     

雾化吸入前列腺素E1预防低吸入氧浓度单肺通气诱发低氧血症的效果

目的评价雾化吸入前列腺素E1(PGE1)预防低吸入氧浓度单肺通气(OLV)诱发低氧血症的效果。方法择期全麻下行左侧开胸食管癌根治术患者60例,性别不限,年龄50～79岁,BMI<30 kg/m2,ASA分级Ⅱ或Ⅲ级。采用随机数字表法分为2组(n=30):PGE1组(P组)和对照组(C组)。OLV开始前,P组经右侧肺雾化吸入PGE1 0.3 μg/kg(生理盐水稀释至10 ml),C组经右侧肺雾化吸入等量生理盐水。于麻醉前 (T0)、诱导后右侧卧位时(T1)、OLV 10 min (T2)、OLV 15 min (T3)、OLV 30 min (T4)、OLV 60 min (T5) 及OLV 120 min (T6) 时采集桡动脉和颈内静脉血样行血气分析,记录PaO2、PaCO2;记录局部脑氧饱和度(rSO2)、Ppeak,计算肺内分流率(Qs/Qt)、rSO2较基础值下降最大百分比。记录OLV期间低氧血症发生情况,术后1周随访肺及脑部并发症发生情况。结果与C组比较,P组低氧血症发生率(3%)降低,T2～4时PaO2升高,Qs/Qt降低(P<0.05),PaCO2、Ppea...     

经胸腔镜肺大泡切除术中应用单肺通气对血气及血液动力学的影响

目的　观察胸腔镜手术中单肺通气时应用不同水平的呼气末正压通气 (PEEP)对血气及血液动力学的影响。方法　随机选择胸腔镜肺大泡切除术病人 36例 ,均分为三组 :A组为单肺间歇正压通气 (IPPV)通气 ;B组为单肺IPPV加PEEP 5cmH2 O通气 ;C组为单肺IPPV加PEEP10cmH2 O通气。分别记录平卧位双肺通气、侧卧位双肺通气、单肺通气 10min和 30min四个时点的血气和血液动力学参数。结果　各组病人SpO2 始终维持在 99%～ 10 0 %。动脉血氧分压 (PaO2 )也在正常范围 ,但B、C组明显高于A组 (P <0 .0 5 )。其余血气指标无明显变化。三组病人HR、MAP、左心室射血时间 (LVET)及体循环血管阻力 (SVR)均无明显变化。B、C组在单肺通气 10min及 30min后 ,每搏量 (SV)及心输出量 (CO)下降明显 ,但均在正常范围 ,且无组间差异。体位改变时血液动力学稳定。结论　经胸腔镜肺大泡切除术中单肺IPPV、PEEP 5cmH2 O均能维持满意的PaO2 和动脉血二氧化碳分压 (PaCO2 ) ,血液动力学变化不显著 ;但PEEP 5cmH2 O较IPPV能进一步提高PaO2 ,PEEP 10cmH2 O不能较PEEP 5cmH2 O进一步提高PaO2 。     

小儿单肺定容和定压通气对血流动力学呼吸力学及血气的影响

目的　探讨小儿单肺通气期间采用定容 (VCV)和定压 (PCV)两种不同通气模式对血流动力学、呼吸力学及血气的影响。方法　按美国麻醉协会病人全身情况评估 (ASA)I～II级择期行结扎术的先天性动脉导管未闭 (PDA)病儿 2 0例 ,麻醉诱导后气管插管 ,右侧卧位 ,先行双肺定容通气 (TLV VCV) ,再采用右肺单肺定容通气 (OLV VCV) ,2 5min后改为单肺定压通气 (OLV PCV) ,用旁气流通气监测法 (SSS)监测TLV VCV、OLV VCV、OLV PCV期间的呼吸力学参数 (Ppeak、Pplat、Raw、Cdyn、Mvi、Mve) ,同时经食管超声多普勒 (TED)监护仪连续监测血流动力学参数 (CO、SVR、SV、LVETi、ACC) ,并取动脉血作血气分析 (PaO2 、PaCO2 )。结果　单肺定容通气与双肺定容通气相比 ,Ppeak、Pplat、Raw显著增高 (P <0 0 1) ,Cdyn显著下降 (P <0 0 1) ;CO、SV显著下降 (P <0 0 5 ) ,SVR显著增加 (P <0 0 5 ) ;动脉血PaO2 显著下降 (P <0 0 1)。单肺定压通气与单肺定容通气相比 ,动脉血PaO2 显著上升 (P <0 0 5 )。结论　单肺通气可使气道压力阻力增加 ,肺顺应性下降 ,动脉血氧分压降低 ,外周血管阻力增加 ,心输出量下降 ;小儿单肺通气期间 ,采取定压通气模式 ,有利于改善肺泡氧合 ,预防和减轻单肺通气造成的低氧血症。     

硬膜外阻滞对全麻单肺通气期间肺内分流和氧合的影响

目的 本研究旨在通过比较全凭静脉麻醉和静脉复合胸部硬膜外麻醉时单肺通气期间肺内分流和动脉氧合的变化，探讨硬膜外麻醉对肺内分流和氧合的影响。方法 24例因肺癌或食管癌需单肺通气开胸手术病人，根据麻醉方法的不同随机分为全凭静脉组（GA，n=12，异丙酚／芬太尼／维库溴铵麻醉）和静脉复合硬膜外组（GE，n=12，异丙酚／维库溴胺／胸部硬膜外0.5%罗哌卡因麻醉）。连续监测MAP，MPAP，CO，ECG，HR，SpO2。分别于清查地、双肺通气30min、单肺通气5，15，30，和60min、再次双肺通气30min、抽取动脉、混合静脉血血样，因气和肺内分流率（Qs/Qt)。结果 单肺通气后，Qs/Qt进行性增加，至15－30min时达到高峰（分别为GA－33．4％和GE－32．4％），GA组和GE组各时间点肺内分流差异无显著性。GA组和GE组单肺通气时PaO2较双肺通气明显下降，至15－30min时最低（分别为165．1mmHg和168．7mmHg)，但两组各时间点PaO2差异无显著性。除GE组平均动脉压轻度降低外，两组心输出量和心率在整个试验中波动不明显。结论 胸部连续硬膜外阻滞不会影响静脉全麻单肺通气期间肺内分流和动脉氧合，可安全有效用于开胸手术。     

不同压力的持续气道正压对化疗后病人单肺通气氧合与分流的影响

目的　探讨应用一种新的持续气道正压 (CPAP)系统在肺癌病人化疗后单肺通气(OLV)时对病人氧合和肺内分流的影响。方法　择期手术病人 30例 ,ASAⅠ～Ⅲ级 ,随机分为对照组 (A组 )、CPAP 2组 (B组 )和CPAP 5组 (C组 ) ,每组 1 0例。A组在OLV期间非通气侧肺的支气管导管直接开口于大气中 ;B组OLV期间非通气侧持续给予CPAP(压力 2cmH2 O) ,C组OLV期间非通气侧持续给予CPAP(压力 5cmH2 O) ,并在平卧双肺通气 2 0min ,仰卧OLV 2 0min ,侧卧OLV2 0、4 0min和关胸双肺通气时 ,分别采取动脉血行血气分析并计算肺内分流率 (Qs/Qt)。结果在OLV后 2 0、4 0min时 ,B、C两组氧合明显高于A组 (P <0 .0 1 ) ,B、C两组Qs/Qt明显低于A组 (P<0 .0 5 ) ,B、C两组之间氧合和Qs/Qt仅在OLV后 4 0min时差异显著。结论　化疗后病人非通气侧持续CPAP ,有助于提高氧合 ,减少肺内分流 ,减少低氧血症的发生率 ,且CPAP 2cmH2 O更易为临床所接受     

低潮气量单肺通气复合呼气末正压对开胸患者免疫功能的影响

目的观察低潮气量单肺通气复合呼气末正压对开胸术患者免疫功能的影响。方法选择ASAⅠ～Ⅱ级择期行开胸手术的病人30例,全麻后插入双腔支气管导管,侧卧位后,行双肺通气,待开胸后行单肺通气。所有病例按单肺通气模式不同分为3组：C组：传统单肺通气;P1组：低潮气量单肺通气复合呼气末正压通气;P2组：单肺通气时。每维均在相同时间点记录呼吸力学参数、血流动力学指标,并作血气分析,检测血浆IL-6、IL-8、IL-10的表达,观察T淋巴细胞亚群以及免疫球蛋白的变化。结果单肺通气时P1、P2两组与C组相比：气道峰压（Ppeak）明显下降（P〈0．01）,PaCO2升高（P〈0．05）,PaO2升高（P〈0．05）,MAP、HR无显著差异;血浆IL-6和IL-8释放减少,IL-10释放增多;与C组相比P1、P2两组免疫功能抑制减弱。结论低潮气量单肺通气复合呼气末正压通气可改善单肺通气氧合、降低气道压、减少炎症反应以及免疫抑制引起的肺损伤。     

气管导管外放置Arndt支气管内阻断器与二氧化碳人工气胸用于婴幼儿单肺通气的比较

目的:比较气管导管外放置Arndt支气管内阻断器与CO 2人工气胸用于婴幼儿单肺通气的通气效果。方法:择期行胸腔镜手术的婴幼儿28例,年龄6~36个月,ASA分级Ⅰ、Ⅱ级。两组患儿在全身麻醉诱导后行Arndt支气管内阻断器或单腔支气管导管置入,术中根据需要行单肺通气。根据患侧肺萎陷方法不同按照随机数字表法分为两组(每组14例):Arndt支气管内阻断器组(A组)和CO 2人工气胸组(C组)。观察记录患儿插管前(T 1)、插管后(T 2)、单肺通气开始时(T 3)、单肺通气结束时(T 4)、拔管时(T 5)MAP、心率、气道压力(airway pressure,Paw)变化及术中重要时间点血气分析中PaO 2、PaCO 2情况。记录、肺萎陷程度、单肺通气时间、拔管时间及术中低氧情况(SpO 2低于90%)。结果:所有患儿均顺利完成手术。A组T 2、T 4、T 5时MAP及T 4、T 5时Paw高于C组(P<0.05),T 3时点的Paw低于C组(P<0.05)。A组肺萎陷即刻评分、肺萎陷20 min评分高于C组(P<0.05)。两组患儿心率、PaCO 2、PaO 2、单肺通气时间、拔管时间及低氧发生率差异无统计学意义(P>0.05)。A组患儿有1例导管移位导致低氧,C组有2例患儿由于长时间胸腔压力过大导致低氧发生,均未导致严重不良后果。结论:气管导管外放置Arndt支气管内阻断器相比CO 2人工气胸应用于婴幼儿单肺通气时,患侧肺萎陷效果更佳,血流动力学更稳定。     

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.