唇腭裂上颌复合体在不同类型上颌截骨内置式牵引下生物力学研究

目的 探讨唇腭裂继发上颌发育不全应用不同类型截骨内置式牵引的生物力学变化特点.方法 采用三维有限元方法,建立唇腭裂上颌复合体Le Fort Ⅰ、Ⅱ、Ⅲ型截骨骨块及相应软组织有限元模型,分别模拟临床上新型内置牵引方式,使截骨块上牵引器固位点沿牵引方向前移10mm,比较分析其生物力学变化情况.结果 唇腭裂上颌复合体不同类型截骨内置式牵引下,Le FortⅠ型截骨腭部出现压缩现象,而Le Fort Ⅱ、Ⅲ型截骨腭部压缩现象不明显.矢向位移比较,Le FortⅢ型截骨内置式牵引可以整体前移截骨体,Le Fort Ⅰ、Ⅱ型截骨存在不同程度的旋转.垂直向位移比较Le FortⅡ型截骨出现较多的逆向旋转.结论 三维有限元仿真研究应用于内置式牵引成骨手术,可以较好地反映颌骨位移情况,为手术计划提供理论依据.     

唇腭裂上颌复合体不同类型上颌截骨外置式牵引下生物力学研究

目的 探讨唇腭裂继发上颌发育不足应用不同类型截骨外置式牵引的生物力学变化特点.方法 采用三维有限元方法,在已建立的唇腭裂上颌复合体Le Fort Ⅰ、Ⅱ、Ⅲ型截骨骨块有限元模型上,分别模拟坚固外固定牵引器(RED系统,rigid external distraction device)外置牵引方式,于牙列承力前下30°牵引截骨块,比较分析其生物力学变化特点.结果 在不同类型截骨RED外置式牵引下,Le Fort Ⅰ型截骨裂隙两侧截骨块后份向内缩窄明显,而前份向裂隙区缩窄不明显.截骨块存在顺时针的旋转,而Le FortⅡ、Ⅲ型截骨腭部压缩现象不明显.截骨块存在逆时针的旋转.结论 外置式牵引成骨三维有限元仿真研究,可以为手术计划提供良好参考.     

唇腭裂上颌复合体不同类型截骨块的抗力中心

目的 探讨唇腭裂上颌复合体不同类型截骨块的抗力中心,以便为临床牵引截骨提供理论指导.方法 采用螺旋CT扫描与三维有限元方法相结合,建立唇腭裂上颌复合体LeFort Ⅰ、Ⅱ、Ⅲ型截骨骨块及相应软组织有限元模型,分别在5个不同垂直高度加载水平向力和4个不同水平距离加载垂直向力,力值均为9.8 N,根据骨块不同观察点位移情况确定不同截骨块的抗力中心.结果 唇腭裂上颌复合体LeFort Ⅱ型截骨骨块的抗力中心前后位置在尖牙与第1双尖牙后缘之间,高度为鼻底与梨状孔中点间.LeFort Ⅲ型截骨骨块的抗力中心前后位置在第1双尖牙后缘与第1磨牙后缘之间,高度为梨状孔中点与鼻前点间.结论 唇腭裂上颌复合体不同截骨块抗力中心的确定,为唇腭裂颅面复合体牵引成骨生物力学研究奠定了基础.     

上颌骨Le Fort-Ⅰ型截骨术坚强内固定的有限元研究

目的 研究不同接骨板在上颌骨Le Fort-Ⅰ型截骨正颌手术中固定的生物力学特性,以期找出最佳固定方法.方法 建立正颌Le Fort-Ⅰ型截骨9种内固定方式的三维有限元模型,并分为3组,计算不同固定方法在3种咬合情况下上颌骨的应力及截骨段的位移,对比不同内固定系统,不同形状接骨板,以及接骨板不同放置位置的固定效果.结果 前牙咬合时,颅、上颌复合体中应力主要循双侧鼻上颌支柱向上传递,前磨牙和磨牙咬合时,应力先自咬合处向牙槽突两侧传递,再分别循颈上颌支柱和鼻上颌支柱传递;内固定系统中螺钉与接骨板交接处及接骨板近截骨线处,为应力集中部位.前磨牙咬合时,不同固定方法截骨段位移从大到小依次为:组1 生物可吸收小型板系统(0.396 509 mm)、微型钛板(0.148 393 mm)、小型钛板(0.078 436 mm);组2 单纯鼻上颌支柱固定(0.188 791 mm)、颧上颌支柱固定(0.12l 718 mm)、双支柱固定(0.078 436 mm);组3 直形板(0.091 023 mm)、L形板(0.078 436 mm)、Y形板(0.072 450 mm)、T形板(O.065 617 ram).结论 正颌Le Fort-Ⅰ型截骨术生物可吸收接骨板固定的稳定性和强度相对钛板较小;颧上颌支柱固定效果好于鼻上颌支柱固定;不同形状的钛板在鼻上颌支柱固定的稳定性有差异.     

下颌骨牵引成骨配合正颌手术矫治成人半侧颜面短小畸形

目的 探讨下颌骨牵引成骨配合正颌手术治疗成人严重半侧颜面短小畸形的方法.方法 将患者三维CT重建数据导入Mimics软件进行手术模拟设计,确定截骨线的位置、牵引向量以及拟牵引的长度并制作手术导板.一期手术行口外入路内置式牵引器置入术,术后5～7d开始骨牵引,延长速度为1 mm/d,牵引结束后,牵引器保留3～6个月.二期手术采用上颌骨Le Fort Ⅰ型截骨,将上颌骨旋转、下降,关闭患侧开颌,采用下颌骨外板植入到上颌截骨下降后的间隙并妥善固定,以保证骨质愈合、维持上颌截骨下降后的稳定性、增加患侧上颌骨的骨体积以增加患侧的丰满度.颏部仍遗留偏斜或形态位置不佳者,同时行颏成形术予以调整.结果 2009年9月至2012年3月,采用上述方法矫治9例半侧颜面短小畸形患者,术后面部对称性、咬合关系趋近正常,效果满意.8例未出现任何并发症,1例上颌切口感染,经清创换药后延迟愈合,未影响面部形态及咬合关系.结论 下颌骨牵引成骨配合正颌手术是矫治成人半侧颜面短小畸形的有效方法.     

中位前牵引颅面骨骼的三维有限元研究

目的探讨中位骨骼前牵引和以牙齿承力前牵引的生物力学变化特点。方法在三维有限元颅面复合体模型上,分别以单个牙齿承力,牙列承力前牵引和中位骨骼前牵引,比较分析其生物力学变化。结果以梨状孔底承力的中位前牵引,矢向位移面中上1/2前移比牙齿或牙列承力的前牵引多,面中下1/2位移相对较少,垂直向及侧向位移值均小于牙齿或牙列承力的前牵引。中位前牵引颅面复合体,鼻根区压应力减少明显。结论与传统的牙体或牙列承力的前牵引比较,上颌中位前牵引可整体前移上颌,从而减少上颌的逆向旋转及硬腭前部压缩现象。     

唇腭裂术后颌骨畸形的正颌外科治疗

目的 探讨正颌外科手术联合术前或术后正畸治疗矫正唇腭裂术后颌骨畸形的效果.方法 自2006年9月至2013年4月,共矫治畸形21例.手术采用LeFortⅠ型截骨＋BSSRO术13例;采用同期骨移植牙槽裂整复＋LeFortⅠ型截骨＋BSSRO术5例;采用LeFortⅠ型截骨＋BSSRO术＋颏成形术3例.行术前、术后正畸治疗18例,其中术后正畸治疗3例.结果 21例手术效果满意,面形良好,术后平均随访10.6个月,无明显复发.结论 正颌外科治疗成年期唇腭裂术后颌骨畸形可取得满意效果.     

牵引成骨技术治疗颌面畸形

目的 探讨应用口外颌骨牵引成骨装置治疗颌面畸形。方法 使用自行设计制作的口外颌骨牵引成骨装置和上颌杠杆式牵引支架分别水平延长下颌骨，水平快速前移上颌骨，垂直延长下颌骨升支，水平延长下颌骨颏部，用以矫正小下颌畸形，下颌骨颏部外伤性骨缺损，小颌偏颌畸形，半侧前面肥大畸形，咬合平面倾余和唇腭裂术后上颌后缩等，共11例。结果 4例不同类型下颌骨牵引成骨，其中有1例在牵引过程中1根克氏针发生松动，旋转，最终将克氏针取出。1例下颌升支垂直牵引4根克氏针发生轻度弯曲，7例唇腭裂上颌后缩行Le Fort Ⅰ型截骨快速牵引成骨中有1例固定期后1个月出现对刃合并有轻度开咬合。最终11例治疗效果满意。结论 口外颌骨牵引成骨装置治疗下颌骨复杂畸形。Le Fort Ⅰ型截骨快速牵引成骨治疗唇腭裂术后上颌后缩是一种安全简便效果可靠的有效方法。     

有限元分析用于水平截骨颏成形术固定方式的生物力学研究

目的应用三维重建和有限元分析的方法探究不同内固定方式对水平截骨颏成形术的影响, 寻找生物力学最佳的固定方式。方法采集1例小颏畸形患者头颅螺旋CT数据, 通过Mimics、Geomagic Studio、Solidworks、Ansys Workbench等软件重建下颌骨三维模型和内固定装置, 模拟手术截骨, 并分别采用4种内固定方法(单纯H形钛板固定、3根拉力螺钉固定、H形钛板联合双侧直形钛板固定、H形钛板联合双侧拉力螺钉固定)进行固定, 通过有限元分析测试在相同载荷条件下各固定方式的形变和应力分布差异。结果 H形钛板联合双侧拉力螺钉固定的效果最均衡, 整体位移小(0.033 2 mm), 内固定材料和游离骨段应力集中小(分别为59.79 MPa和4.69 MPa), 区域应力小[内固定材料等效应力组间比较时, 除与3根拉力螺钉固定方式相近(P>0.05)外, 明显小于另2种固定方式(P<0.01);游离骨段等效应力组间比较时, 除与单纯H形钛板固定方式相近(P>0.05)外, 明显小于另2种固定方式(P<0.05)]。结论水平截骨颏成形术使用H形钛板联合双侧拉...     

下颌角截骨移植隆颏术

目的探讨利用自体下颌角截骨块同期移植隆颏的手术方法。方法经口腔入路,利用下颌角肥大截骨术的下颌角骨块,塑形为适合颏部的形状,Ⅰ期移植于颏部,且以钛钉坚强内固定。结果本组35例患者行双侧下颌角截骨+下颌骨外板磨削术+自体下颌角移植隆颏术,术后移植骨愈合良好,颏部形态符合美学标准。结论下颌角截骨Ⅰ期移植隆颏术,操作方法简单,预期效果可靠,移植骨块与颏部解剖结合,无排异反应。     

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.     

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.     

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.