影响骨质疏松患者椎弓根螺钉固定强度的相关技术进展

<正>20世纪50年代,Boucher率先使用椎弓根螺钉固定行脊柱融合术;60年代Roy-Camille推广了该技术。此后椎弓根螺钉内固定被广泛用于胸椎和腰椎手术,其经过椎弓根进入椎体,对脊柱"三柱"均有稳定作用。随着人口的老龄化,越来越多的人罹患骨质疏松,骨质疏松人群的脊柱手术也常需采用椎弓根螺钉固定。然而椎弓根螺钉的抗拔出力与骨密度密切相关,扩大的骨小梁网状结构会降低对椎弓根螺钉的把持力,导致内固定松动~[1、2]。为了改善骨     

改进螺钉设计提高骨质疏松条件下椎弓根螺钉稳定性的研究进展

椎弓根螺钉内固定系统是脊柱外科常用的后路内固定技术之一。骨质疏松患者由于椎体骨密度（bone mineraldensity,BMD）降低,骨小梁变薄,常导致螺钉松动甚至断裂。有研究表明：BMD与轴向拔出力呈正相关,BMD的降低会严重影响螺钉的稳定性。为了提高椎弓根螺钉在体内的稳定性,国内外学者在通过改进螺钉的设计提高螺钉的把持力方面做了大量的研究,笔者对近年来这方面的研究进展作一综述。     

PMMA骨水泥强化椎弓根钉在骨质疏松性脊柱疾病治疗中的应用进展

正椎弓根钉内固定技术已经被广泛地应用于脊柱外科~([1-2]),但对于骨质疏松性椎体,由于螺钉对椎体的把持力不足,常出现螺钉松动、断裂甚至脱出。有研究通过对骨质疏松患者术后随访发现,椎弓根钉松动率高达60%~([3])。如何增加椎弓根钉的把持力成为脊柱外科医师需要关注的热点问题之一,目前有学者尝试了不同方式解决这一问题:(1)增加椎弓根钉的长度和直径~([4-5]);(2)改进螺钉设计~([6]);(3)使用可膨胀式椎弓根钉~([7]);(4)骨     

胸椎椎弓根螺钉置入技术的研究现状与展望

自20世纪50年代末,椎弓根螺钉被应用于脊柱后路内固定以来,经椎弓根固定技术已成为脊柱外科中发展最为迅速的内固定技术之一[1]。椎弓根是三柱理论中较强的固定点,经椎弓根螺钉固定具有强大的把持力和三维控制力,能提高固定的稳定性,从而减少固定和融合节段,并     

皮质骨轨迹螺钉在脊柱外科中的应用进展

<正>椎弓根螺钉(pedicle screw,PS)因能够固定脊柱三柱达到稳定的三维固定效果,自其发明以来一直广泛应用于各种脊柱外科手术。然而螺钉松动、断裂、拔出等各种并发症往往导致固定失败,尤其对于骨质疏松的患者,螺钉松动是最为常见的并发症~([1、2])。因此,对于骨量下降的患者,如何提高PS的把持力及稳定性是一个亟待解决的问题。临床医师往往通过延长脊柱固定节段或结合骨水泥强化钉道等方法提高骨质疏松患者脊柱内固定的稳定性~([3、4])。然而     

骨水泥强化骨质疏松性椎体椎弓根螺钉的研究进展

目前椎弓根螺钉固定技术作为脊柱后路稳定的"金标准",已被广泛应用于临床.如果病人合并骨质疏松症,其内固定失败的风险将大大增加.骨水泥强化技术不仅能够显著提高骨质疏松性椎体术后骨质疏松椎体的稳定性,还能明显改善固定节段的周期性抗屈能力,为骨质疏松性椎体提供坚强、持久的内固定,从而有效重建脊柱的稳定性.但骨水泥强化技术也存在并发症,如骨水泥渗漏、加快邻近节段退变、增加骨折风险等.本文通过对骨水泥强化椎弓根螺钉固定的力学特性、骨水泥的选择、强化方式及近远期并发症等方面对骨水泥强化椎弓根螺钉固定技术进行综述.     

空心侧孔椎弓根螺钉的研究进展

目的对空心侧孔椎弓根螺钉(fenestrated pedicle screw,FPS)的研发背景、生物力学特征及临床应用进行综述。方法查阅近年国内外有关FPS的文献并进行综述。结果与传统椎弓根螺钉钉道强化相比,FPS能够通过中空孔及侧边孔实现聚甲基丙烯酸甲酯(polymethyl methacrylate,PMMA)强化,术中操作更简便。强化后的FPS能够在骨质疏松椎体牢固锚定,同时能降低PMMA渗漏风险。结论 FPS是脊柱内固定技术的一大创新,有望提高PMMA强化椎弓根螺钉固定骨质疏松椎体的疗效。     

增强椎弓根螺钉系统对脊柱固定稳定性的研究进展

椎弓根螺钉固定系统是目前临床上应用最多的脊柱后路内固定方法[1] 。它通过椎弓根这个“力核”达到三维固定[2 ] 。然而对于骨质疏松患者 ,因其脊柱的骨质状况较差 ,故很难获得稳固的内固定 ,给脊柱外科手术带来极大困难 ,如何提高椎弓根螺钉系统对骨质疏松患者脊柱固定的稳定性 ,是当前脊柱外科亟待解决的难题。本文就近年来对加强椎弓根螺钉系统稳定性的研究进展作一综述。1　增加螺钉直径直径大的螺钉能增强螺钉的稳定性 ,其抗拔出力亦增强。Mclain等[3] 用直径 7.0mm椎弓根螺钉替换 6 .0mm螺钉 ,其拔出强度变化较小 ,而改用 8.0mm螺钉…     

皮质骨轨迹螺钉在腰椎融合术中的初步应用

正腰椎椎弓根螺钉置入是目前腰椎融合手术中常用的固定方法。从后方结构经椎弓根直至椎体内贯穿"三柱"的螺钉可以为固定提供充足的把持力。然而,对于骨质疏松患者,由于骨密度降低,骨松质薄弱、稀疏,使得椎弓根螺钉固定的强度减弱,以致出现松动、切割、拔出等并发症,影响腰椎融合术的手术效果。为此,有学者通过改进螺纹设计、改良置钉方法以及应用骨水泥强化等方法提高骨质     

胸椎椎弓根螺钉置入技术研究进展

椎弓根螺钉（pedicle screw，PS）固定技术是脊柱后路内固定方法最显著的进展。近年来，椎弓根螺钉内固定系统已广泛应用于脊柱畸形、脊柱骨折脱位、脊椎滑脱和退变性椎间盘病变等多种疾病的治疗，极大地推进了脊柱外科的进展。胸椎作为脊柱的重要组成部分，其位置和解剖结构都有较大的特殊性，椎弓根矢状径、横向宽度及矢状面角度变化较大，而且其周围有较多重要的血管和神经。胸椎椎弓根螺钉固定失败后极易造成严重后果。因此，对胸椎椎弓根螺钉固定技术的研究显得尤为重要。笔者就胸椎解剖特点及胸椎椎弓根螺钉置人方法和相关的辅助技术进行综述。     

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.