不同潮气量机械通气诱发的肺损伤大鼠肺组织中CXCR2表达

目的探讨不同潮气量机械通气大鼠肺组织中巨噬细胞炎性蛋白2(MIP-2)及CXCR2蛋白的表达。方法清洁级Wistar大鼠30只,雄雌不拘,体重200～250g,随机均分为三组。实验前12h禁食,自由饮水。对照组,仅作气管切开插管,不行机械通气;小潮气量组潮气量VT7ml/kg,大潮气量组VT40ml/kg,两组气管切开插管后接小动物呼吸机控制呼吸,调节RR40次/分,吸呼比1∶2,空气吸入,通气4h,建立机械通气诱发肺损伤大鼠动物模型。对照组在气管插管后即刻,余两组在机械通气结束后,立即剖胸,取大鼠肺组织,收集支气管肺泡灌洗液(BALF)。RT-PCR法测定肺组织中CXCR2的mRNA表达、免疫组化测定肺组织CXCR2的蛋白表达和HE染色观察肺组织病理学变化,ELISA法测定肺组织匀浆中MIP-2蛋白水平,测定BALF中PMN计数。结果与对照组和小潮气量组比较,大潮气量组MIP-2蛋白及其受体CXCR2蛋白和mRNA表达增加(P<0.05),灌洗液中PMN计数增加(P<0.05),肺炎症反应明显加重;与对照组比较,小潮气量组上述指标无明显变化。结论大潮气量机械通气引起肺组织中炎症因子MIP-2及其受体CXCR2表达增加,肺组织炎症反应明显,损伤加重,是机械通气相关肺损伤的发生机制之一。     

鸢尾素对呼吸机相关性肺损伤大鼠细胞焦亡的影响

目的探讨鸢尾素对呼吸机相关性肺损伤大鼠细胞焦亡的影响。方法健康清洁级雄性SD大鼠36只, 体重200～250 g, 6～8周龄, 采用随机数字表法分为3组(n=12):对照组(C组)、呼吸机相关性肺损伤组(V组)和呼吸机相关性肺损伤+鸢尾素组(V+I组)。V+I组机械通气前尾静脉注射鸢尾素1 μg/kg。机械通气(潮气量40 ml/kg, 通气频率60次/min, 吸呼比设为1∶2, PEEP 0, FiO2 21%)4 h后采集股动脉血样, 进行动脉血气分析, 记录PaO2, 计算氧合指数(OI);收集支气管肺泡灌洗液(BALF), 测定总蛋白浓度, 采用ELISA法测定BALF和血清IL-1β、IL-18浓度。取肺组织, HE染色后行肺损伤评分, 测定肺组织湿重/干重(W/D)比值;分别采用Western blot法和RT-PCR法检测焦亡相关蛋白消皮素D-N端(GSDMD-N)、caspase-1及其mRNA的表达水平。结果与C组比较, V组肺损伤评分和W/D比值升高, PaO2和OI降低, BALF总蛋白浓度、BALF和血清IL-1β、IL-18浓度升高, 肺组织caspase...     

血管紧张素Ⅱ受体在大鼠机械通气所致肺损伤中的作用

【摘要】目的研究血管紧张素Ⅱ受体（AT1型）在机械通气所致肺损伤中的作用。方法40只健康SD大鼠随机分成4组（n=10）：对照组（A组）、正常潮气量机械通气组（B组）、大潮气量机械通气组（C组）和大潮气量机械通气加洛沙坦预处理组（D组）。A组不行机械通气，B组潮气量（VT）为10ml／kg，C组VT为40ml／kg，D组实验前1周每天用血管紧张素Ⅱ受体（AT1型）特异性阻滞剂洛沙坦溶液100mg灌胃后，行大潮气量机械通气，VT为40ml／kg。机械通气2h后处死大鼠，收集肺组织和支所管肺泡灌洗液，光镜下观察肺组织病理改变，RT-PCR法检测A组、B组和C组肺组织中AT。受体mRNA的表达，同时测定支气管肺泡灌洗液总蛋白、白细胞计数、肺湿，干重比（W／D）和中性粒细胞髓过氧化物酶（MPO）、巨噬细胞炎症蛋白-2（MIP-2）的水平。结果C组和D组肺泡间隔明显增厚，肺泡腔内有渗出物，可见较多的炎性细胞浸润，其病理损伤程度较A组和B组重。与A组和B组比较，C组和D组AT1受体mRNA表达、支气管肺泡灌洗液中总蛋白浓度、白细胞计数、MIP-2浓度和肺组织中MPO活性、W／D均增高（P〈0．01）；与C组比较，D组上述各项指标均降低（P〈0．05或0．01）。结论AT1受体参与了大鼠机械通气所致肺损伤。     

肥胖因素对大鼠呼吸机相关性肺损伤的影响

目的评价肥胖因素对大鼠呼吸机相关性肺损伤(VILI)的影响。方法清洁级雄性SD大鼠45只,6～8周龄,按照体重分为3组(n=15):正常体重对照组(C组)、正常体重VILI组(CV组)和肥胖VILI组(FV组)。C组和CV组体重为233～267 g,FV组体重为288～332 g。C组潮气量VT 10 ml/kg,CV组和FV组潮气量VT 40 ml/kg,通气频率40次/min,吸呼比1∶ 2,PEEP 0 mmHg,FiO2 21%,机械通气4 h,制备大鼠VILI模型。分别于气管插管前即刻和机械通气4 h时采集动脉血样行血气分析,记录PaO2;剩余血样收集血浆。机械通气4 h时采血后处死大鼠,分离两侧肺组织,收集支气管肺泡灌洗液(BALF)。采用ELISA法检测血浆瘦素浓度、血浆及BALF中TNF-α、IL-1β、IL-6的浓度。测定肺组织湿重/干重(W/D)比值,HE染色后观察肺组织病理结果并进行肺损伤评分,采用Western blot法检测肺组织NF-κB p65表达水平。结果与C组和CV组比较,FV组血浆瘦素浓度升高(P<0.01)。与C组比较,CV组和FV组机械通气...     

不同剂量瘦素对大鼠机械通气肺损伤的影响

目的评价不同剂量瘦素对大鼠机械通气肺损伤的影响。方法健康清洁级SD雄性大鼠48只,6～8周龄,采用随机数字表法分为四组:气管切开保留自主呼吸的假手术组(A组)、机械通气模型组(B组)、瘦素10μg/kg组(C组)和瘦素50μg/kg组(D组),每组12只。采用10%水合氯醛3.5 ml/kg麻醉大鼠,疼痛反射消失后C组腹腔注射瘦素10μg/kg,D组腹腔注射瘦素50μg/kg,A、B组腹腔注射等容量生理盐水,注射后即刻进行气管切开,插管机械通气。A组气管插管后保留自主呼吸,B、C、D组机械通气建立VILI模型,参数设置:V_T 20 ml/kg,RR 80次/分,I∶E 1∶1,FiO_2 21%,PEEP 0 mmHg,通气时间4 h。分别于基础状态、通气结束时抽取股动脉血进行血气分析。通气结束后放血处死大鼠,在4℃下取肺组织并收集支气管肺泡灌洗液(bronchoalveolar lavage fluid, BALF),光镜下进行中性粒细胞计数,采用ELISA法测定TNF-α、IL-6、IL-1β浓度;取肺组织称重,计算肺湿干重比(W/D);观察肺组织病理改变并进行病理评分;采用Western blot检测肺组织研磨液中NF-κB p65含量。结果与A组比较,B、C、D组W/D、肺损伤评分、BALF中性粒细胞计数、TNF-α、IL-6、IL-1β浓度及肺组织NF-κB p65含量明显升高(P0.01)。与B组比较,C、D组BALF中性粒细胞计数、TNF-α、IL-6、IL-1β浓度及肺组织肺损伤评分、NF-κB p65含量明显降低(P0.05)。与C组比较,D组BALF中性粒细胞计数、TNF-α、IL-6、IL-1β浓度及肺组织肺损伤评分、NF-κB p65含量明显降低(P0.05)。结论瘦素可降低大鼠机械通气肺损伤中炎性因子的表达水平,减轻肺损伤,50μg/kg较10μg/kg作用明显。     

机械通气致肺损伤大鼠肺组织基质金属蛋白酶的表达

目的探讨机械通气致肺损伤大鼠肺组织基质金属蛋白酶(MMP-2和MMP-9)及其组织抑制因子(TIMP-1和TIMP-2)的表达。方法30只健康雄性SD大鼠随机分为3组,麻醉和气管切开及气管内插管后,进行三种方式通气,A组(对照组):保留自主呼吸;B组(小潮气量组):Vr 7ml/kg, 呼吸频率(RR)40次/min;C组(大潮气量组):Vr 40ml/kg,RR 20次/min;B、C组大鼠通气时间均为4 h。测定实验前及通气4 h后PaO2/FiO2、通气4 h后支气管肺泡灌洗液(BALF)中白细胞计数、总蛋白水平及左肺湿重/干重(W/D)比值,并行肺组织病理学检查,RT-PCR检测肺组织MMP-2、MMP-9、TIMP-1和TIMP-2 mRNA的表达;酶谱法分析BALF中MMP-2和MMP-9的活性。结果通气4 h后,与A、B组比较,C组PaO2/FiO2下降,BALF中总蛋白含量、白细胞计数、W/D比值以及MMP-2、MMP-9活性增高,肺组织MMP-2、MMP-9 mRNA表达水平增高,TIMP-1、TIMP-2 mRNA表达水平无明显变化,肺组织有更多的白细胞浸润和肺泡壁结构的破坏。结论大潮气量通气可致大鼠急性肺损伤,MMP-2和MMP-9及TIMP-1和TIMP-2的失衡在其中发挥重要作用。     

氟比洛芬酯对大鼠机械通气所致肺损伤的影响

目的 探讨氟比洛芬酯对大鼠机械通气所致肺损伤的影响.方法 健康成年雄性SD大鼠40只,体重300～350 g,随机分为4组(n=10),常规潮气量通气组(TV组,潮气量8 ml/ks)、大潮气量通气组(HV组,潮气量40 ml/ks)、大潮气量通气+氟比洛芬酯5 ms/kg组(HV+F1组)和大潮气量通气+氟比洛芬酯10 mg/kg组(HV+F2组).HV+F1组和HV+F2组于机械通气前15 min时分别静脉注射氟比洛芬酯5、10 mg/ks.于机械通气4 h时处死大鼠,测定支气管肺泡灌洗液(BALF)肿瘤坏死因子α(TNF-α)、白细胞介素6(IL-6)、血栓素B2(TXB2)和总蛋白浓度,计数白细胞及计算肺组织湿/干重比(W/D),光镜下观察肺组织病理学结果.结果 与TV组相比,HV组BALF TNF-α、IL-6、TXB2、总蛋白浓度、白细胞计数和肺组织W/D升高(P<0.05),肺组织发生病理学损伤;与HV组相比,HV+F1组和HV+F2组BALF TNF-α、IL-6、TXB2、总蛋白浓度、白细胞计数和肺组织W/D降低(P<0.05),肺组织病理学损伤减轻;HV+F2组BALF TNF-α和TXB2浓度低于HV+F1组(P<0.05),其余指标差异均无统计学意义(P>0.05).结论 氟比洛芬酯可通过抑制炎性反应减轻大鼠机械通气所致肺损伤.     

Rho/Rock 信号通路在大鼠呼吸机相关性肺损伤中的作用

目的评价Rho/Rock信号通路在大鼠呼吸机相关性肺损伤(ventilator-induced lung injury,VILI)中的作用。方法选择健康雄性SD大鼠96只,12~15周龄,体重300~350g,采用随机数字表法将大鼠随机分为四组:空白对照组(C组)、Rho激酶抑制药法舒地尔组(F组)、高潮气量组(H组)和高潮气量+Rho激酶抑制药法舒地尔组(HF组),每组24只。C组和F组不行机械通气,H组和HF组行高潮气量40ml/kg机械通气4h。F组和HF组在机械通气前1h给予腹腔注射法舒地尔10mg/kg。分别于通气前(T0)、通气后4h(T1)、8h(T2)和24h(T3)每组随机取6只大鼠,采集血样,测定血清TNF-α、IL-6及IL-10浓度;采血结束后处死大鼠,收集支气管肺泡灌洗液(BALF),采用考马斯亮兰法检测BALF总蛋白;测定肺组织湿/干重比(W/D);光镜下行肺组织病理学损伤评分;采用分光光度法检测肺组织髓过氧化物酶(MPO)活性;采用Western blot和RT-PCR法分别检测肺组织RhoA、Rock2蛋白含量和mRNA表达水平。结果与C组比较,T1~T3时H组和HF组大鼠血清TNF-α、IL-6及IL-10浓度、BALF总蛋白含量、肺组织W/D、病理学损伤评分、MPO活性、RhoA、Rock2蛋白含量和mRNA表达水平明显升高(P0.05);与H组比较,T1~T3时HF组大鼠血清TNF-α、IL-6浓度、BALF总蛋白含量、肺组织W/D、病理学损伤评分、MPO活性、RhoA、Rock2蛋白含量和mRNA表达水平明显下降,血清IL-10浓度明显升高(P0.05)。结论Rho激酶抑制药法舒地尔可减轻大鼠呼吸机相关性肺损伤,其机制可能与其抑制Rho/Rock信号通路,降低肺组织内炎性反应有关。     

金雀异黄素预先给药对大鼠机械通气所致肺损伤的作用

目的 研究特异性蛋白酪氨酸激酶抑制剂金雀异黄素预先给药对大鼠机械通气所致肺损伤（VILI）的作用。方法 30只健康SD大鼠，随机分为3组，每组10只，A组采用8ml／kg潮气量机械通气；B组采用40ml／kg潮气量机械通气；C组采用40ml／kg潮气量机械通气，并在机械通气前30min腹腔注射金雀异黄素50mg／kg。3组呼吸频率均为80次／min，吸／呼比（I：E）为1：1，PEEP为0，吸人气体为室内空气。机械通气2h后处死大鼠，取肺组织，光镜下观察病理学，测定髓过氧化物酶（MPO）活性、磷酸化p38（p-p38）、p38水平；收集支气管肺泡灌洗液，测定总蛋白、肿瘤坏死因子-α（TNF-α）水平，并进行白细胞（WBC）计数。结果与A组比较，B组支气管肺泡灌洗液总蛋白、WBC计数、TNF-α及肺组织MPO、P—p38／p38水平升高（P〈0．05或0．01），肺组织病理学改变严重；与B组比较，C组上述指标降低（P〈0．01或0．05），肺组织病理学改变明显减轻。结论 金雀异黄素50mg／kg预先给药可减轻大鼠VILI，其机制与抑制了p38通路的激活有关。     

大鼠机械通气相关性肺损伤时蛋白激酶Cδ与细胞焦亡的关系

目的评价大鼠机械通气相关性肺损伤时蛋白激酶Cδ(PKCδ)与细胞焦亡的关系。方法清洁级健康成年雄性SD大鼠36只,体重200～250 g,采用随机数字表法分为3组(n=12):对照组(C组)、机械通气相关性肺损伤组(VILI组)和PKCδ特异性抑制剂KAI 9803组(K组)。气管插管术后VILI组气管内注射200 μl磷酸缓冲盐溶液,K组气管内注射KAI 9803 200 μg/kg,行机械通气4 h(潮气量40 ml/kg、通气频率60次/min,吸呼比1∶1,吸入氧浓度21%,呼气末正压为0)。于机械通气结束时采集股动脉血样,进行动脉血气分析,记录PaO2。通气结束后麻醉处死大鼠,取肺组织,制备支气管肺泡灌洗液(BALF),光镜下观察肺组织病理学结果并行肺损伤评分,计算肺组织湿重/干重(W/D)比值,采用考马斯亮蓝法测定BALF总蛋白浓度,采用ELISA法测定BALF IL-18和IL-1β浓度,分别采用Western blot法和qRT-PCR法测定肺组织PKCδ、gasdermin D N端片段(GSDMD-N)及其mRNA的表达。结果与C组比较,VILI组和K组肺损伤评分和...     

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.