后中路椎间盘镜治疗腰椎间盘突出症

目的　探讨后中路椎间盘镜手术系统治疗腰椎间盘突出症的适应证、操作要点以及并发症处理。方法　采用后中路椎间盘镜椎间盘摘除术 (MicroendoscopicDiscectomy ,MED)对椎间盘突出症患者行髓核摘除和神经根管扩大术。结果　本组 46例 ,随访 3～ 12个月 ,按Nakai分级 :优 40例 ,良 5例 ,可 1例。结论　MED具有创伤小、恢复快、手术效果好的优点 ,适用于大多数椎间盘突出症或合并侧隐窝狭窄患者     

显微椎间盘镜治疗合并神经根管狭窄的腰椎间盘突出症

目的分析内镜下后路椎间盘髓核摘除，神经根减压、松解术冶疗合并腰椎管狭窄的椎间盘突出症的临床疗效。方法对合并侧隐窝及神经根管狭窄的腰椎间盘突出症58例，采用后路显微内镜（MED）下髓核摘除、神经根管扩大术治疗。结果术后58例症状均明显改善，未出现损伤椎体前方大血管、神经症状加重、脑脊液外漏和感染等近期并发症和复发、腰椎失稳等远期并发症。结论内镜下后路髓核摘除术是外科治疗椎间盘突出症的一种优良方法，对合并神经根管狭窄病例，正确把握手术适应证，发挥微创技术的优越性，同样可以取得满意疗效。     

后中路椎间盘镜治疗腰椎间盘突出症

目的：探讨后中路椎间盘镜手术系统治疗腰椎间盘突出症的适应证、操作要点以及并发症处理。方法：采用后中路椎间盘镜椎间盘摘除术（Microendoscopic Discectomy,MED)对椎间盘突出症患者行髓核摘除和神经根管扩大术。结果：本组46例,随访3-12个月,按Nakai分级：优40例,良5例,可1例。结论：MED具有创伤小、恢复快、手术效果好的优点,适用于大多数椎间盘突出症或合并侧隐窝狭窄患者。     

后路椎间盘镜髓核摘除治疗腰椎间盘突出症

目的探讨椎间盘镜下髓核摘除治疗腰椎间盘突出症的方法。方法经后路椎间盘镜下髓核摘除治疗腰椎间盘突出症72例。结果全部病例经5个月～2年的随访，按Macnab评分，优51例，良15例，可6例，无症状及体征加重病例，优良率93％。结论经后路椎间盘镜下髓核摘除治疗腰椎间盘突出症能够取得满意效果。     

椎间盘镜下腰椎间盘髓核摘除术的疗效

目的 探讨椎间盘镜下腰椎间盘髓核摘除术的手术要点和早期疗效。方法 在椎间盘镜直视下对50例单间隙腰椎间盘突出症患者行突出髓核摘除术，并进行疗效分析。结果 患者均在术后10天出院，平均随访9.34个月，临床疗效优良率96%，无严重手术并发症，术后CT检查显示突出椎间盘已摘除，脊髓及神经根已获得充分减压。结论 椎间盘镜下腰椎间盘髓核摘除术创伤小，患者术后恢复快，疗效肯定，是治疗腰椎间盘突出症的有效方法之一。     

椎板间隙入路椎间盘镜治疗腰椎间盘突出症

目的　探讨椎板间隙入路椎间盘镜手术系统治疗腰椎间盘突出症的适应症、操作要点以及并发症处理。方法　采用椎板间隙入路椎间盘镜椎间盘摘除术 (MicroendoscopicDiscectomy ,MEDⅡ )对腰椎间盘突出症患者行髓核摘除和神经根管扩大术。结果　本组 55例 ,随访 3～ 1 2个月 ,根据中华骨科学会脊柱学组腰背痛手术评定标准 :优 49例 ,良 6例 ,差 0例。结论　MED具有创伤小、恢复快、手术效果好的优点 ,适用于大多数椎间盘突出症     

ETRX手术系统治疗腰椎间盘突出症早期疗效观察

报道应用METRX椎间盘镜手术系统治疗腰椎间盘突出症 6 4例 ,行髓核摘除和神经根管扩大术。随访 3月～ 19月 ,平均 11个月。按Nakai分级 :优 5 6例 ,良 6例 ,可 2例。并发症 5例 ,其中硬脊膜损伤 3例 ,神经根牵拉伤 1例 ,髓核残留 1例。     

坐俯卧位显微椎间盘镜治疗腰椎间盘突出症及腰椎侧隐窝狭窄症

目的探讨后路显微椎间盘镜治疗腰椎间盘突出症及腰椎侧隐窝狭窄症的临床效果：方法手术均取坐俯卧位,经椎板间隙只切除黄韧带不切除椎板及其它结构,应用椎间盘镜及显微外科的技术摘除突出之髓核和／或神经根减压术：临床应用649例。结果术后所有病例均获随访,随访最长时间24个月,最短6个月,平均12个月,按Nakai标准评定,其中优594例,良45例。结论侧卧位经椎板间隙入路行椎间盘镜治疗腰椎间盘突出症及腰椎侧隐窝狭窄症的手术损伤小、出血少,术后不影响脊柱稳定性,临床疗效可靠。     

椎间盘镜手术治疗腰椎间盘突出症

目的：评价椎间盘镜手术治疗腰椎间盘突出症的临床疗效。方法：腰椎间盘突出症患者15例，男11例，女4例；平均年龄39．8岁。在椎间盘镜下行腰椎间盘髓核切除、椎板减压及神经根管扩大术。术前在X线机下，分别于病变节段上位棘突下缘、上位椎板下缘中点定位，置人内窥镜头。在椎间盘镜配套的监视器下咬除部分椎板下缘及黄韧带，扩大椎板间隙，清除椎间盘髓核组织，扩大神经根管。结果：本组除1例患者因术中硬膜囊破裂改为开放手术，其余14例平均手术出血量60ml，平均手术时问86min。本组平均随访时间13．2个月，按照Nakai评级，优11例，良3例，可1例。结论：椎间盘镜手术治疗腰椎间盘突出症比常规手术方法视野清晰、创伤小、恢复快，基本保持了脊柱后柱完整。     

显微内窥镜治疗合并腰椎管狭窄症的椎间盘突出症

目的 探讨后路显微内窥镜经椎板间隙入路行椎间盘摘除术及神经根管扩大术治疗腰椎间盘突出症合并腰椎管狭窄的技术特点和效果分析.方法 对68例腰椎间盘突出症合并腰椎管狭窄应用后路显微内窥镜系统行髓核摘除及神经根管减压手术治疗.结果 60例随访3～48个月,按Nakai标准评定:优43例,良13例,可3例,差1例,优良率93....     

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.     

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.