几丁糖膜预防椎板切除术后硬膜周围粘连的实验研究

目的：观察几丁糖膜对预防椎板切除术后硬膜周围粘连的作用。方法：２４只成年新西兰白兔Ｌ３、Ｌ５水平切除椎板１０×０５ｃｍ,Ｌ３硬膜外放置几丁糖膜（Ａ点）,Ｌ５作为空白对照（Ｂ点）。分别于术后３周、６周、１２周进行大体形态、组织学观察。结果：Ａ点硬膜与瘢痕无明显粘连,硬膜外有空隙,未见明显异物、炎症反应;Ｂ点硬膜与瘢痕紧密粘连,瘢痕侵入椎管内,对硬膜有压迫。结论：几丁糖膜具有明显的预防硬膜周围粘连的作用。     

椎板切除术后预防硬膜外瘢痕粘连的实验研究

为了寻找预防椎板切除后硬膜粘连的材料，选用家兔３０只，随机分为三组，每组１０只。每只作Ｌ３、Ｌ５椎板切除，形成两个大小１ｃｍ×０．５ｃｍ的缺损，一个缺损无任何覆盖，作空白对照；另一个缺损分别在硬膜外覆盖几丁糖、聚乳酸（ＰＬＡ）膜及明胶海绵，即为几丁糖组、ＰＬＡ膜组及明胶海绵组。术后２，４，６，８及１０周处死动物，通过肉眼、光镜及透射电镜，观察瘢痕生长及硬膜外粘连情况。结果表明，几丁糖组和ＰＬＡ膜组硬膜外均光滑、无增厚，硬膜外腔隙未见纤维组织增生或粘连；几丁糖具有明显抑制成纤维细胞生长和促进表皮细胞生长的作用，切口愈合快。而各组空白对照和明胶海绵组硬膜外纤维组织增生或粘连明显，硬膜外腔隙基本消失。认为，可生物降解吸收的几丁糖、ＰＬＡ膜能有效地预防椎板切除术后瘢痕粘连。     

选择性脊神经后根切除术椎板切除后硬膜外防粘连的实验研究

目的观察选择性脊神经后根切除术（ＳＰＲ）椎板切除后硬膜外几种防瘢痕粘连物质的作用并探讨其机制。方法用４８只ＳＤ大鼠制作硬膜外周围粘连模型,在损伤的硬膜表面分别涂布透明质酸钠、自体游离脂肪、几丁糖、生理盐水,分别于４、８、１２周观察瘢痕形成情况并测定胶原纤维含量。结果生理盐水组大鼠硬膜外瘢痕自第４周开始形成,于第８周达高峰,１２周时开始软化、收缩;透明质酸钠与几丁糖预防瘢痕形成均有明显效果,其中几丁糖明显优于透明质酸钠;组织相容性以自体游离脂肪最好,其次是几丁糖、透明质酸钠。结论几丁糖对硬膜外周围瘢痕形成、粘连有明显预防作用     

几丁糖联合聚乳酸薄膜预防硬膜外粘连的研究

目的 观察几丁糖加聚乳酸薄膜联合运用对椎板切除术后预防硬膜外瘢痕粘连的效果.方法 80只成年家兔[体质量(2.0±0.2)kg]制作椎板切除模型,在椎板缺损处分别覆盖等渗盐水(A组)、聚乳酸薄膜(B组)、几丁糖(C组)及几丁糖加聚乳酸薄膜(D组),术后12周对椎板切除部位进行大体观察、组织学观察及透射电镜比较各组间瘢痕形成和粘连情况.结果 B、C、D组的Rydell-Balazs粘连度评分、Nussvaum组织学评分均优于A组(P<0.01),D组优于B组和C组(P<0.01),B组与C组间差异无统计学意义(P>0.05).结论 联合应用几丁糖加聚乳酸薄膜能有效预防硬膜外瘢痕粘连,比单独应用几丁糖或聚乳酸薄膜效果好.     

几丁糖联合聚乳酸薄膜预防硬膜外粘连的研究

目的 观察几丁糖加聚乳酸薄膜联合运用对椎板切除术后预防硬膜外瘢痕粘连的效果.方法 80只成年家兔[体质量(2.0±0.2)kg]制作椎板切除模型,在椎板缺损处分别覆盖等渗盐水(A组)、聚乳酸薄膜(B组)、几丁糖(C组)及几丁糖加聚乳酸薄膜(D组),术后12周对椎板切除部位进行大体观察、组织学观察及透射电镜比较各组间瘢痕形成和粘连情况.结果 B、C、D组的Rydell-Balazs粘连度评分、Nussvaum组织学评分均优于A组(P<0.01),D组优于B组和C组(P<0.01),B组与C组间差异无统计学意义(P>0.05).结论 联合应用几丁糖加聚乳酸薄膜能有效预防硬膜外瘢痕粘连,比单独应用几丁糖或聚乳酸薄膜效果好.     

几丁糖联合聚乳酸薄膜预防硬膜外粘连的研究

目的 观察几丁糖加聚乳酸薄膜联合运用对椎板切除术后预防硬膜外瘢痕粘连的效果.方法 80只成年家兔[体质量(2.0±0.2)kg]制作椎板切除模型,在椎板缺损处分别覆盖等渗盐水(A组)、聚乳酸薄膜(B组)、几丁糖(C组)及几丁糖加聚乳酸薄膜(D组),术后12周对椎板切除部位进行大体观察、组织学观察及透射电镜比较各组间瘢痕形成和粘连情况.结果 B、C、D组的Rydell-Balazs粘连度评分、Nussvaum组织学评分均优于A组(P<0.01),D组优于B组和C组(P<0.01),B组与C组间差异无统计学意义(P>0.05).结论 联合应用几丁糖加聚乳酸薄膜能有效预防硬膜外瘢痕粘连,比单独应用几丁糖或聚乳酸薄膜效果好.     

几丁糖联合聚乳酸薄膜预防硬膜外粘连的研究

目的 观察几丁糖加聚乳酸薄膜联合运用对椎板切除术后预防硬膜外瘢痕粘连的效果.方法 80只成年家兔[体质量(2.0±0.2)kg]制作椎板切除模型,在椎板缺损处分别覆盖等渗盐水(A组)、聚乳酸薄膜(B组)、几丁糖(C组)及几丁糖加聚乳酸薄膜(D组),术后12周对椎板切除部位进行大体观察、组织学观察及透射电镜比较各组间瘢痕形成和粘连情况.结果 B、C、D组的Rydell-Balazs粘连度评分、Nussvaum组织学评分均优于A组(P<0.01),D组优于B组和C组(P<0.01),B组与C组间差异无统计学意义(P>0.05).结论 联合应用几丁糖加聚乳酸薄膜能有效预防硬膜外瘢痕粘连,比单独应用几丁糖或聚乳酸薄膜效果好.     

高分子透明质酸钠预防椎板切除术后硬膜外粘连的实验研究

[目的]通过动物实验观察高分子透明质酸钠和几丁糖对预防椎板切除术后硬膜外瘢痕粘连的作用。[方法]45只纯种日本大耳白兔,随机分成A、B、C、三组,制作L3、4椎板损伤模型,A组硬膜外涂布生理盐水,B组硬膜外涂布几丁糖,C组硬膜外涂布高分子透明质酸钠。于术后12周分别对椎板切除部位进行大体形态、组织学观察及生化检查,比较各组间瘢痕形成和粘连情况。[结果]C组改良Rydell-Balazs、胶原含量及改良Nussvaum组织学评分均优于A组和B组(P0.05),A组与B组比较差异无统计学意义(P0.05)。[结论]高分子透明质酸钠可以减轻或者预防椎板切除术后硬膜外瘢痕粘连的形成。     

几丁糖联合聚乳酸薄膜预防硬膜外粘连的研究

目的 观察几丁糖加聚乳酸薄膜联合运用对椎板切除术后预防硬膜外瘢痕粘连的效果.方法 80只成年家兔[体质量(2.0±0.2)kg]制作椎板切除模型,在椎板缺损处分别覆盖等渗盐水(A组)、聚乳酸薄膜(B组)、几丁糖(C组)及几丁糖加聚乳酸薄膜(D组),术后12周对椎板切除部位进行大体观察、组织学观察及透射电镜比较各组间瘢痕形成和粘连情况.结果 B、C、D组的Rydell-Balazs粘连度评分、Nussvaum组织学评分均优于A组(P<0.01),D组优于B组和C组(P<0.01),B组与C组间差异无统计学意义(P>0.05).结论 联合应用几丁糖加聚乳酸薄膜能有效预防硬膜外瘢痕粘连,比单独应用几丁糖或聚乳酸薄膜效果好.     

几丁糖联合聚乳酸薄膜预防硬膜外粘连的研究

目的 观察几丁糖加聚乳酸薄膜联合运用对椎板切除术后预防硬膜外瘢痕粘连的效果.方法 80只成年家兔[体质量(2.0±0.2)kg]制作椎板切除模型,在椎板缺损处分别覆盖等渗盐水(A组)、聚乳酸薄膜(B组)、几丁糖(C组)及几丁糖加聚乳酸薄膜(D组),术后12周对椎板切除部位进行大体观察、组织学观察及透射电镜比较各组间瘢痕形成和粘连情况.结果 B、C、D组的Rydell-Balazs粘连度评分、Nussvaum组织学评分均优于A组(P<0.01),D组优于B组和C组(P<0.01),B组与C组间差异无统计学意义(P>0.05).结论 联合应用几丁糖加聚乳酸薄膜能有效预防硬膜外瘢痕粘连,比单独应用几丁糖或聚乳酸薄膜效果好.     

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.     

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.     

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.     

Dilemma of Membrane Biocompatibility and Reuse

Abstract: Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation. leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.