吸入一氧化氮对犬感染性ARDS时肺表面活性物质及肺形态学的影响

目的研究吸入一氧化氮(NO)对感染性ARDS时肺表面物质和组织形态学的影响.方法犬感染性ARDS建立后,随机分成两组,单纯机械通气组(对照组,n=6),机械通气+吸入NO组(干预组,n=6),NO吸入浓度分别为10、20、40、80 ppm各1h,然后降至10ppm持续吸入6h.待实验结束后,取左下叶肺组织标本进行组织学检查及肺组织湿/干重比值(W/D).右肺用0.9%NaCI溶液15～20 ml/kg进行支气管肺灌洗,测定灌洗液(BALF)中总磷脂(TPL),饱和磷脂(DSPC)及总蛋白(TP)含量.结果(1)单纯机械通气组BALF中DSPC/TP及DSPC/TPL明显降低,NO吸入组BALF中DSPC/TP、DSPC/TPL降低程度减轻,两组相比有明显差异(P＜0.05);(2)肺W/D在NO吸入组为3.42±1.56,单纯机械通气组为4.89±0.52(P＜0.05);(3)光镜、电镜可见毛细血管淤血,血管内PMN聚集,内皮细胞及肺泡上皮细胞肿张,空泡变性.肺间质及肺泡水肿,内充满大量红细胞及白细胞,并可见透明膜形成,肺泡上皮变性、坏死,NO吸入组上述变化程度减轻.结论感染性ARDS时吸入一氧化氮可减轻肺表面物质受损程度;对其肺组织形态改变不明显.     

JNK信号转导通路在大潮气量机械通气诱发兔肺泡巨噬细胞分泌IL-8和TNF-α中的作用

目的 评价c-Jun氨基末端激酶(JNK)在大潮气量机械通气诱发兔肺泡巨噬细胞分泌IL-8和TNF-α中的作用.方法 清洁级雄性新西兰白兔30只,体重210～260 g,随机分为3组(n=10):正常对照组(C组)不予任何刺激;机械通气组(V组)大潮气量机械通气3 d,VT 15 ml/kg,I∶E 1∶2,RR 30～40次/min,PEEP 0;SB203580干预组(S组)大潮气量机械通气3 d,同时每天机械通气时静脉注射JNK特异性抑制剂(SB203580)6 mg/kg,通气参数同V组.采用ELISA法检测支气管肺泡灌洗液中IL-8和TNF-α浓度,同时收集肺泡巨噬细胞,体外培养2 h后应用RT-PCR法检测IL-8 mRNA和TNF-α mRNA水平.结果 与C组比较,V组TNF-α、TNF-α mRNA、IL-8、IL-8 mRNA水平升高(P＜0.05).与V组比较,S组TNF-α和TNF-α mRNA水平降低(P＜0.01),IL-8和IL-8 mRNA水平差异无统计学意义(P＞0.05).结论 JNK信号转导通路在大潮气量机械通气诱发兔肺泡巨噬细胞分泌TNF-α过程中起重要作用,而不参与分泌IL-8的过程.     

吸入一氧化氮对犬感染性ARDS的效应

目的研究吸入不同浓度一氧化氮(NO)对犬感染性急性呼吸窘迫综合征(ARDS)的效应。方法 感染性ARDS建立后,12只纯处毕格犬随机分成两组,单纯机械通气组(对照组,n=6),机械通气+吸入NO组(NO组,n=6)。NO吸人浓度分别为10、20、40、80 ppm,各浓度吸1 h,然后降至10 ppm吸6 h。通过以下指标变化分析判断吸入NO对ARDS的影响:体、肺循环血液动力学参数;氧合指数(PaO2/FiO2)、分流率(Qs/Qt)、肺动态顺应性(cdyn)、死腔量(VD/VT)及气道阻力(Rrs);外周血中性粒细胞计数;血、尿中亚硝酸根/硝酸根浓度(NO2-/NO3-);血正铁血红蛋白含量及动物存活时间。结果 吸人10、20、40、80 ppm.NO,PaO2/FiO2增加超过50％,Qs/Qt下降<25％,VD/VT下降至0.36,PVRI下降近50％,一定程度改善Cdyn,与单纯机械通气组相应时相点比,差异有显著性(P均<0.01),动物存活时间为(10.2±1.7)h显著高于对照组(4.4±1.2)h(P<0.01);NO浓度由80 ppm降至10 ppm时,改善的Qs/Qt,PaO2/FiO2,PVRI,VD/VT及Cdyn等指标又回落,实验最后阶段,随病程发展,肺部情况恶化;吸入NO可减轻外周血白细胞下降程度,与对照组相比差异有显著性(P<0.01)。结论 吸入10～80 ppm NO可明显降低犬感染性ARDS时肺血管阻力,改善通气,血流比例,对ARDS产生一定的治疗作用。     

结直肠癌微环境中细胞因子的表达及其与CD16a mRNA表达的相关性研究

目的探讨结直肠癌肿瘤微环境中细胞因子的表达及其与CD16a mRNA表达的关系。方法分别采用实时荧光定量PCR法和流式细胞术微球阵列法(CBA法)检测42例结直肠癌组织及其癌旁组织中CD16a mRNA和8种细胞因子[包括白细胞介素(IL)-2、IL-4、IL-6、IL-10、IL-12、肿瘤坏死因子-α(TNF-α)、γ-干扰素(IFN-γ)和血管内皮生长因子(VEGF)]的表达水平,分析两者之间的相关性。结果结直肠癌组织中IL-6、TNF-α和VEGF的表达水平高于癌旁组织(P<0.05),而IL-2、IL-4、IL-10、IL-12和IFN-γ在2种组织中的表达水平比较差异均无统计学意义(P>0.05)。术前CEA正常组的IL-6和VEGF的表达水平高于术前CEA升高组(P<0.05)。相关性分析结果显示:结直肠癌组中IL-6的相对表达水平与CD16a mRNA的表达水平呈负相关(P<0.05)。结论结直肠癌组织中IL-6、TNF-α和VEGF的表达水平较癌旁组织明显升高,提示促血管生成作用及免疫抑制增强。此外,结直肠癌肿瘤微环境中CD16a mRNA的表达与IL-6的表达呈负相关。     

中度低温对内毒素性急性呼吸窘迫综合征大鼠肺细胞因子表达的影响

目的 研究中度低温对内毒素性急性呼吸窘迫综合征(ARDS)大鼠模型肺细胞因子表达的影响,探讨其用于防治ARDS的可能性。方法 腹腔注射内毒素(LPS)1 ml/kg(0.3 ml),16 h后在机械通气下气管内滴注1 mg(0.5 ml)LPS建立大鼠内毒素性ARDS模型。32只大鼠随机分为ARDS常温组(AN组)、ARDS低温组(AH组)、生理盐水常温组(NN组)及生理盐水低温组(NH组),每组8只。建模成功后3 h处死大鼠,用酶联免疫吸附法测定4组动物支气管肺泡灌洗液(BALF)中肿瘤坏死因子(TNF-α)、白细胞介素-6(IL-6)的浓度。结果 气管内滴注LPS后成功建立大鼠内毒素性ARDS模型。AH组BALF中TNF-α、IL-6的浓度显著低于AN组(P<0.01)。NH组与NN组比较,TNF-α、IL-6的含量差异无显著性(P>0.01)。结论 低温有显著抑制内毒素性ARDS大鼠模型肺表达TNF-α、IL-6的作用,提示中度低温可能成为防治ARDS的辅助方法。     

盐酸戊乙奎醚对脓毒症大鼠肺组织炎性反应的影响

目的 探讨盐酸戊乙奎醚对脓毒症大鼠肺组织炎性反应的影响.方法 雄性SD大鼠96只,随机分为4组(n=24):假手术组(S组)、盲肠结扎穿孔组(CLP组)、小剂量盐酸戊乙奎醚组(PH1组)和大剂量盐酸戊乙奎醚组(PH2组).PH1组和PH2组于CLP后即刻分别经尾静脉注射盐酸戊乙奎醚0.1、0.3 mg/kg(用生理盐水稀释至1 ml/kg),S组和CLP组分别给予等容量生理盐水.分别于CLP后3、6、12和24 h(每个时点6只大鼠)经左心室采血,测定血浆中性粒细胞CD11b表达,采血后处死大鼠,观察肺组织中性粒细胞浸润及病理学结果,测定肺组织肿瘤坏死因子-α(TNF-α)含量,CLP后6 h时测定肺组织NF-κB表达及肺血管内皮细胞(PVEC)ICAM-1表达.结果 与S组比较,CLP组、PH1组和PH2组肺组织中性粒细胞计数、TNF-α含量、NF-κB和PVEC ICAM-1表达升高,CLP组及PH1组血浆中性粒细胞CD11b表达升高(P＜0.05或0.01);与CLP组比较,PH1组和PH2组肺组织中性粒细胞计数、TNF-α含量、NF-κB及PVEC ICAM-1表达及血浆中性粒细胞CD11b表达降低(P＜0.05或0.01);与PH1组比较,PH2组肺组织NF-κB、PVEC ICAM-1表达及血浆中性粒细胞CD11b表达降低(P＜0.05或0.01).结论 盐酸戊乙奎醚可通过降低肺组织NF-κB、TNF-α和PVEC ICAM-1水平,下调血浆中性粒细胞CD11b表达,减少肺组织中性粒细胞的浸润,减轻了脓毒症大鼠肺损伤.     

一氧化氮吸入时段对大鼠肺缺血-再灌注损伤的影响

目的通过建立在体大鼠肺缺血-再灌注(I-R)损伤模型,观察不同时段吸入20ppm一氧化氮(NO)对大鼠肺I-R损伤的作用。方法40只SD大鼠随机分为五组,I组为假手术组,即左侧开胸,游离肺门,但不夹闭肺门;Ⅱ组为I-R组,夹闭左肺门60min后松开,再灌注3h;Ⅲ组为NO预处理组,即在夹闭前,先吸入20ppmNO30min;Ⅳ组为再灌注即刻NO吸入组,即再灌注即刻吸入20ppmNO30min;V组为再灌注30minNO吸入组,即再灌注30min后吸入20ppmNO30min。检测肺组织白细胞介素-10(IL-10)、IL-1β、肿瘤坏死因子α(TNF-α)以及细胞间黏附分子-1(ICAM-1)表达,丙二醛(MDA)和髓过氧化物酶(MPO)含量和肺组织湿干重比。结果吸入NO可在一定程度上抑制肺I-R后IL-1β和TNF-α的生成,降低ICAM-1的上调,减少MDA和MPO生成,同时抑制IL-10生成。其中Ⅳ组MDA、MPO与Ⅲ、Ⅴ组相比增高,但差异无统计学意义。结论不同时段NO吸入对大鼠肺I-R损伤保护作用不同,与再灌注即刻吸入NO相比,NO预处理以及再灌注30min后NO吸入组的保护作用更加完善,为较佳NO吸入时段。     

吸入异氟烷对大鼠血浆和肺脏IL-1β和IL-10水平的影响

目的 通过观察吸入异氟烷大鼠血浆和肺脏IL-1β和IL-10水平的变化,探讨异氟烷对肺组织局部和全身炎性反应的影响.方法 雄性Wiser大鼠32只,随机分为4组(n=8):对照组(C组)、异氟烷4 h组(Iso-4 h组)、8 h组(Iso-8 h组)和恢复组(R组).C组仅吸入空气;Iso-4 h组、Iso-8 h组分别吸入40% O2+1.5%异氟烷4、8 h;R组吸入40%O2+1.5%异氟烷8 h后停止吸入异氟烷,继续吸入40%O2 2 h.采集股动脉血样检测血浆白细胞介素-1β(IL-1β)和IL-10浓度;处死大鼠后行支气管肺泡灌洗,收集支气管肺泡灌洗液(BALF),测定IL-1β和IL-10浓度;取右肺组织测定IL-1β mRNA和IL-10 mRNA表达.结果 与C组比较,Iso-4 h组BALF IL-1β浓度升高,肺组织IL-1β mRNA表达上调,Iso-8 h组BALF和血浆IL-1β、IL-10浓度升高,肺组织IL-1β mRNA和IL-10 mRNA表达上调(P<0.05),R组BALF和血浆IL-1β、IL-10浓度、肺组织IL-1β mRNA、IL-10 mRNA表达差异无统计学意义(P>0.05);与Iso-4 h组比较,Iso-8 h组BALF和血浆IL-10浓度升高,肺组织IL-10 mRNA表达上调(P<0.05);与Iso-8 h组比较,R组BALF和血浆IL-1β、IL-10浓度降低,肺组织IL-1β mRNA和IL-10 mRNA表达下调(P<0.05).结论 吸入异氟烷可诱发大鼠一过性肺组织局部和全身炎性反应.     

术前雾化吸入布地奈德对开胸手术患者单肺通气时炎性反应的影响

目的 评价术前雾化吸入布地奈德对开胸手术患者单肺通气时炎性反应的影响.方法 肺叶切除术患者50例,年龄20 ～ 60岁,体重50 ～ 80 kg,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将其分为2组(n=25):对照组(C组)和布地奈德组(B组).术前C组雾化吸入生理盐水20 min;B组雾化吸入布地奈德1 mg 20 min.分别于单肺通气前(T1)、单肺通气结束后30 min(T2)、术后24 h(T3)和48 h(T4)时采集动脉血样,进行血气分析；采集静脉血样,采用ELISA法测定血清TNF-α、IL-1、IL-6、IL-8和IL-10的浓度.分别于T1和T2时,记录气道峰压、气道平台压和肺顺应性,采用ELISA测定支气管肺泡灌洗液TNF-α、IL-1、IL-6、IL-8和IL-10浓度.结果 与C组比较,B组T1和T2时气道峰压和气道平台压降低,肺顺应性升高,T2时支气管肺泡灌洗液中TNF-α、IL-1、IL-6和IL-8的浓度降低,T2-4时氧合指数升高,血清TNF-α、IL-1、IL-6和IL-8的浓度降低(P＜0.05),各时点PaCO2比较差异无统计学意义(P＞0.05).结论 术前雾化吸入布地奈德可抑制开胸手术患者单肺通气时的炎性反应,有助于改善肺功能.     

急性坏死性胰腺炎肺组织炎性介质mRNA表达与肺损伤的关系

目的 探讨急性坏死性胰腺炎(ANP)大鼠肺组织白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)及细胞间黏附分子(ICAM-1)等炎性介质mRNA表达与肺损伤的关系.方法 33只Wistar大鼠随机分为正常对照和胰腺炎不同时间点(1、4、12和24 h)各组,应用3.5%牛磺胆酸钠逆行胰胆管注射制备ANP模型.采用RT-PCR法检测ANP肺组织IL-6、TNF-α及ICAM-1 mRNA表达,同时观察血淀粉酶及脂肪酶、胰腺和肺组织湿/干重比率及病理改变.结果 造模ANP 1 h后肺组织IL-6、TNF-α及ICAM-1 mRNA水平(1.25±0.16、0.33±0.09及082±0.03)较正常对照组(0.07±0.02、0.06±0.02及0.41±0.04)表达增高(P<0.05),并持续升高至12及24 h(分别为1.674±0.14、0.99±0.11、1.17士0.05及1.87±0.05、0.96士0.06、1.11士0.04),同时伴有肺组织病理损害,其严重程度与肺TNF-α及ICAM-1 mRNA表达、肺组织湿/干重比率与TNF-α、IL-6、ICAM-1 mRNA表达的相关系数分别为0.93及0.70(P<0.05).结论 大鼠ANP早期肺组织IL-6、TNF-α及ICAM-1mRNA即过度表达,肺IL-6、TNF-α及ICAM-1mRNA过度表达是ANP肺损害发生的原因之一,肺损伤严重程度与IL-6、TNF-α及ICAM-1mRNA表达的高低有关.     

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 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.     

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.     

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.     

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.     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

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.