自由基对缺血游离皮瓣的损伤和超氧化物歧化酶抗损伤…

采用兔下腹部游离皮瓣模型，通过结扎股动脉造成皮瓣缺血１２小时，在吻合血管恢复血运之前，分别用生理盐水和超氧化物歧化酶（ＳＯＤ）灌注皮瓣，分别测定正常、缺血、用药物灌注后和血液再灌注后皮肤中ＳＯＤ的活性和丙二醛的含量，并记录各组皮瓣成活面积，结果表明，游离皮瓣缺血再灌注时有自由基产生，自由基对皮瓣有损伤作用，ＳＯＤ局部灌注可提高缺血游离皮瓣的成活率。     

热应激预处理对皮瓣缺血再灌注损伤的影响及机制

目的　探索减轻皮瓣缺血再灌注损伤的有效措施。方法　采用大鼠腹部岛状皮瓣,制作活体原位热缺血模型,观察热缺血再灌注后皮瓣的成活率、皮瓣组织形态学改变,检测皮瓣超氧化物歧化酶（ Ｓ Ｏ Ｄ） 活性、丙二醛（ Ｍ Ｄ Ａ） 含量、 Ｈ Ｓ Ｐ７ ０ 表达。结果　缺血８ｈ 后再灌注,实验组皮瓣存活率明显高于对照组;与对照组相比,实验组皮瓣组织中 Ｓ Ｏ Ｄ 活性较高而 Ｍ Ｄ Ａ 水平较低;电镜显示,实验组皮瓣毛细血管内膜较完整,细胞肿胀轻,线粒体结构较稳定。结论　热应激预处理,能减轻缺血再灌注对皮瓣的损伤,对缺血再灌注皮瓣具有保护作用,其机制可能与热应激预处理抗自由基损害作用及维护细胞膜结构稳定有关。     

大鼠皮瓣缺血再灌注损伤的电子顺磁共振观察

为了研究大鼠皮瓣在缺血再灌注时氧自由基的变化，我们应用电子顺磁共振技术，对缺血再灌注后的ＳＤ大鼠腹壁岛状皮瓣进行了直接检测。结果表明大鼠腹壁皮瓣在缺血再灌注以后产生大量的超氧阴离子自由基；Ｏ２变化十分活跃，大鼠腹壁皮瓣是ＥＰＲ研究氧自由基的较理想的模型。     

大鼠皮瓣缺血再灌注损伤的电子顺磁共振观察

为了研究大鼠皮瓣在缺血再灌注时氧自由基的变化，我们应用电子顺磁共振（ＥＰＲ）技术，对缺血再灌注后的ＳＤ大鼠腹壁岛状皮瓣进行了直接检测。结果表明大鼠腹壁皮瓣在缺血再灌注以后产生大量的超氧阴离子自由基（Ｏ－·２）；Ｏ－·２变化十分活跃；大鼠腹壁皮瓣是ＥＰＲ研究氧自由基的较理想的模型。     

丹参酮防治心肌再灌注损伤的实验研究

采用家兔心肌缺血再灌注模型，观察了缺血和再灌注后心肌ＭＤＡ生成、ＳＯＤ活性、血清ＣＫ活性的变化以及ＤＳ－２０１对上述指标的影响。结果表明：缺血再灌注后，心肌ＭＤＡ含量显著升高，ＳＯＤ活性明显降低，同时血清ＣＫ活性显著增高。缺血和再灌注前给ＤＳ－２０１（５ｍｇ／ｋｇ）能显著降低心肌中ＭＤＡ的生成和减少心肌ＣＫ的释放。用化学发光法显示ＤＳ－２０１对超氧阴离子、羟基自由基和过氧化氢有清除作用。由此推测Ｄ     

氧自由基对肌皮瓣缺血再灌注的损伤及维生素C对损伤的防护

目的探讨氧自由基对肌皮瓣的损伤及机体对自由基的清除过程，以及维生素Ｃ等抗氧化剂的作用规律。方法以大白兔为动物模型，形成缺血再灌注肌皮瓣，动态测定缺血、再灌注不同时间内超氧化物歧化酶（ＳＯＤ）、谷胱甘肽过氧化物酶（ＧＳＨ－Ｐｘ）、丙二醛（ＭＤＡ）变化及静脉滴注维生素Ｃ对其影响。结果缺血再灌注损伤在缺血期已经开始，随着缺血时间的延长而加重，再灌注时损伤进一步加重，超氧阴离子自由基（Ｏ－２）、羟自由基（·ＯＨ）于再灌注后不久即被清除，脂质过氧化物的清除需要较长时间，维生素Ｃ对缺血再灌注损伤有一定的保护作用。结论在组织移植中应争取最短的缺血、最快的再灌注，应用药物抗氧化时应于缺血前用药并持续至再灌注后数天。     

氧自由基对肌皮瓣缺血再灌注的损伤及维生素C对损伤的防护

目的 探讨自由基对肌皮瓣的损伤及机体对自由基的清除过程，以及维生素Ｃ等抗氧化剂的作用规律。方法 以大白兔为动物模型，形成缺血再灌注肌皮瓣，动态测定缺血、再灌注不同时间内超氧化物歧化酶（ＳＯＤ）、谷胱甘肽过氧化物酶（ＧＳＨ－Ｐｘ）、丙二醛（ＭＤＡ）变化及静脉滴注维生素Ｃ对其影响。结果 缺血再灌注损伤在缺血期已经开始，随着缺血时间的延长而加重，再灌注时损伤进一步加重，超氧阴离子自由基（Ｏ２＾－）、羟自     

尼群地平对缺血再灌注肺脂质过氧化反应的影响

目的探讨肺缺血再灌注损伤的发病机理，观察尼群地平的防治效果。方法７２只大鼠随机分成假手术组、缺血再灌注组和治疗组，采用肺在体温缺血再灌注损伤模型，于缺血４５分钟、再灌注后１小时、２小时、４小时取损伤肺组织测丙二醛（ＭＤＡ）、超氧化物歧化酶（ＳＯＤ）和总钙含量。结果缺血再灌注组各时相肺组织ＭＤＡ含量上升（Ｐ＜０．０５），ＳＯＤ含量显著下降（Ｐ＜０．０５），总钙含量显著升高（Ｐ＜０．０５），尼群地平可减轻肺组织ＭＤＡ和组织总钙含量的升高（Ｐ＜０．０５）。结论钙超载和自由基反应共同参与了肺缺血再灌注损伤，二者可能相互影响，相互促进；尼群地平通过阻滞钙通道，影响自由基系统而对缺血再灌注肺起保护作用     

高压氧与水飞蓟联合应用对肢体缺血再灌注损伤的防治及其机制

２８只健康标准新西兰兔分成假手术组、对照组、水飞蓟宾组、高压氧组、高压氧水飞蓟宾联合组，以一侧后肢造成缺血再灌注损伤模型，缺血６ｈ，再灌注１ｈ，分别取实验侧胫前肌标本测定ＭＤＡ．ＳＯＤ、ＡＴＰ，ＰＣｒ，Ｃａ＾＋＋－ＡＴＰａｓｅ及进行超微结构检查，取心、肺、肾组织进行ＭＤＡ．ＳＯＤ检查。结果显示高压氧水飞蓟宾联合治疗肢体缺血再灌注损伤具有明显减轻脂质过氧化损害的作用，增高ＳＯＤ活力及ＡＴＰ，ＰＣｒ水     

联合应用超氧化物歧化酶,阿魏酸钠抗肝缺血再灌注损伤

目的研究联合应用外源性超氧化物歧化酶（ＳＯＤ）与阿魏酸钠（ＳＦ）对肝缺血再灌损伤的保护作用。方法将３２只成年雄性ＳＤ大鼠随机分为对照组、ＳＦ保护组、ＳＯＤ保护组和ＳＦ与ＳＯＤ联合保护组。通过阻断大鼠肝门１ｈ后再开放建立肝缺血再灌注损伤模型,在肝缺血前及肝再灌注２ｈ时测肝组织丙二醛（ＭＤＡ）,ＳＯＤ和测血谷丙转氨酶（ＡＬＴ）,谷草转氨酶（ＡＳＴ）。并取肝组织作光镜及电镜观察。结果再灌注２ｈ时ＳＦ保护组与ＳＯＤ保护组的肝组织ＭＤＡ生成,ＳＯＤ消耗,血清ＡＬＴ,ＡＳＴ升高值均高于ＳＦ与ＳＯＤ联合保护组（Ｐ＜０．０１或Ｐ＜０．０５）,且ＳＦ和ＳＯＤ联合保护组的肝细胞显微、超微结构损害的改变较ＳＯＤ或ＳＦ保护组轻。结论ＳＦ与ＳＯＤ联合保护组清除氧自由基（ＯＦＲ）的作用强于ＳＯＤ或ＳＦ保护组,对鼠肝缺血再灌注所致肝细胞的结构和功能损伤的保护作用比单独使用ＳＯＤ或ＳＦ强。     

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.