Mechanical Accuracy of a New Stereotactic Guide

Summary ? Objective. A new stereotactic guide using a navigational computer is developed for stereotactic procedures. In order to compare the mechanical accuracy of the guide to frame based systems, an error analysis study was designed.  Methods. A biopsy procedure was simulated using a phantom model. Targets with known co-ordinates in a three-dimensional Cartesian co-ordinate system were positioned inside the skull model. A biopsy needle was inserted along computer set trajectories from three different entry points. The position of the biopsy needle in the co-ordinate system was measured. Distance from needle tip to target was calculated and defined as the error of the system for each trial. The results were statistically analyzed for precision and biasedness.  Results. A total of 242 accuracy measurements (182 on two MRI scans, 60 on one CT scan) were carried out. Mean incision length along the trajectories was 59 mm. Mean error using MRI scans was 3.8 mm and for the CT scan 2.9 mm. The error of the stereotactic computer was found to be 1.0 mm with both MR and CT imaging. The main cause of error for the MRI based trials was distortion of the magnetic field.  Conclusion. The results indicate a stereotactic system with high degree of accuracy. This is confirmed by a clinical study of 39 biopsies where all tumours were reached. MRI affected the mechanical accuracy significantly due to distortion of the magnetic field. The accuracy is comparable to other studies performed on both stereotactic computers and frame based systems.     

呼吸机治疗新生儿肺透明膜病预后多因素分析

目的分析呼吸机治疗新生儿肺透明膜病(HMD)的疗效及影响预后的因素。方法对2000年1月~2002年12月在我科NICU呼吸机治疗的54例HMD患儿进行总结,分析其疗效,比较治愈组与病死组胎龄、出生体重、上机日龄、上机前血气及吸气峰压(PIP)、呼吸未正压(PEEP)、各种并发症的差异。结果呼吸机治疗新生儿HMD的治愈率为68.4％;病死组胎龄、出生体重均明显低于治愈组(P<0.05),病死组上机时的日龄及上机前的血pH值均明显小于治愈组(P<0.01),病死组呼吸机参数PIP、PEEP均明显高于治愈组(P<0.05),两组间各种并发症的比较差异无显著性。结论呼吸机是治疗新生儿HMD的主要手段;HMD患儿胎龄越小,体重越低,则病变发生越早,上机前酸中毒越明显,病死率就越高。     

新生儿机械通气后远期肺功能随访

目的　了解新生儿机械通气对远期肺功能及反复呼吸道疾病影响。方法　新生儿期用呼吸机治疗16例患儿 ,8年后对其进行随访 ,并作肺功能检测。结果　 5 0 %患儿有反复呼吸道疾病症状 ,75 %患儿肺功能异常 ,其中残气量 /肺总量 (RV/TLC)为 5 6 .2 5 %、肺活量 2 5 %时最大呼气流量 (Vmax 2 5 )为 4 3.7%、特殊呼吸道阻力 (sRaw)及特殊呼吸道传导 (sGaw)均为 5 0 %。吸气峰压 (PIP) >2 5cmH2 O组用力肺活量中期平均呼气流速 (FEF 2 5 %～ 75 % )及 5 0 %用力肺活量时的最大呼气流速 (Vmax 5 0 )低于PIP <2 5cmH2 O组。呼气末正压 (PEEP)≤ 4cmH2 O组sRaw >4cmH2 O组。结论　新生儿机械通气可影响远期肺功能。较高PIP或过低PEEP可引起肺损伤 ,从而引起呼吸道阻力增加 ,呼吸道高反应。而儿童期反复呼吸道疾病可能与肺损伤后支气管反应性增高有关     

早产儿肺出血机械通气治疗探讨

目的:探讨低机械通气参数治疗早产儿肺出血的疗效及应用价值。方法:将96例肺出血早产儿随机分为较低机械通气参数(IPPV+PEEP)治疗组和常频机械通气参数(IPPV+PEEP)对照组,并对结果进行统计学分析。结果:治疗组52例肺出血早产儿中存活45例,死亡6例,放弃治疗1例;对照组44例肺出血早产儿中存活27例,死亡11例,放弃治疗6例。存活者平均机械通气治疗时间79h(最短10h,最长120h)。结论:采用机械通气能显著提高早产儿肺出血治愈率,可大大降低早产儿肺出血的死亡率。低机械通气参数比常频机械通气参数优越。     

老年机械通气患者气管内导管生物被膜形成状况的研究

目的：探讨老年机械通气患者气管内导管生物被膜的形成状况,明确相关性和危险因素.方法：分析22例老年患者的25个气管导管各留置时间段与细菌培养结果.结果：25个气管导管细菌培养阳性22个,占88%,培养阴性的3个,占12%.结论：细菌密度与气管插管时间密切相关,随着插管时间的延长,细菌计量明显增加.     

红外遥控式可升降医疗病床的设计

介绍了一种基于红外遥控技术的可升降医疗病床。论述了病床机械结构的设计及其工作原理、红外遥控电路的设计及其工作原理。该病床具有成本低廉、使用方便、运行可靠、能持久连续使用等优点。     

Stretch of mammalian nerve in vitro: effect on compound action potentials

Stretch of nerve has been reported to decrease the amplitude of the compound action potential (CAP) with a complete block appearing in approximately 30 minutes. But for the most part, those experiments were carried out in vivo, and it is generally accepted that the failure of responses was due to a closure of vessels supplying the nerve with a resulting ischemia and anoxia. These studies were undertaken to determine if stretch of nerve has effects that are independent of interference with its vascular supply. In the studies, lengths of rat sciatic and dog peroneal nerves were removed and placed in a chamber supplied with oxygen in which their CAPs were continuously elicited and recorded. This in vitro preparation obviated interference with the nerve's metabolism on stretching. We have previously shown that the form change termed 'beading,' appearing within 10 seconds and reversing as quickly on relaxation, can be elicited with tensions of only several grams. We wished to determine if stretch adequate to produce beading could alter CAPs with the same rapidity. Tensions below 2 g had little effect. On applying tensions of 10-100 g, levels well above those needed to bead the fibers, both increases and decreases of CAP amplitude were seen. The changes occurred within 10 seconds of stretch application, the time at which beading arises with stretch. Although the decreases of CAP amplitudes could be accounted for by beading, the degree of CAP change did not correspond to the amount of tension applied. We hypothesize that the constrictions in the beaded fibers increase axial resistivity and diminish local currents so as to block conduction. The lack of an increasing degree of decreased CAP amplitude with increases in tension is ascribed to the inhibition of elongation offered by the collagen fibrils present in nerve. Collagenase applied to nerves allowed a further increase in length, producing a 'hyperbeading,' showing much longer lengths of beading constrictions on stretch. This would further increase axial resistance and is taken to account for the greater decreases of CAP amplitudes seen following collagenase treatment. To account for those cases where increases of CAP amplitude were seen on stretch, we hypothesize that stretch can also cause an increase in the excitability of the nodes. The outcome of stretch in any given nerve would be the resultant of two opposing actions; beading of the internodes causes a decrease of local currents leading to block of CAPs, while an increased excitability of the nodes acts to augment the responses.     

白内障超声乳化联合机械性房角分离治疗闭角型青光眼

目的：观察前房角镜辅助下的机械性房角分离术联合超声乳化白内障摘除和IOL植入治疗原发性闭角型青光眼(PACG)合并白内障的疗效。

方法：选取45例52眼房角镜下粘连性房角关闭≥180°的PACG合并白内障患者,接受前房角镜辅助下的机械性房角分离术联合超声乳化白内障摘除。术后随访6mo,观察并记录患者术前和术后1、2、3、6mo的最佳矫正视力、眼压、房角粘连范围,以及术中和术后并发症。

结果：术前眼压为33.92±5.45mmHg,术后1、2、3、6mo眼压分别为15.40±2.67、15.65±2.65、15.57±2.50、16.17±2.65mmHg,术后眼压较术前均明显降低(均P<0.01)。

结论：超声乳化白内障摘除联合前房角镜辅助下房角分离术对于PACG疗效确切。     

机械通气治疗有机磷中毒IMS的调查及护理对策

目的 了解有机磷中毒IMS患者机械通气期间的需求,主动提供适合患者需要的人性化护理服务。方法 对32例呼吸机辅助呼吸患者进行回顾性调查。结果 患者的需求是多方面的。结论 针对品德的不同需求提出相应的护理对策取得了良好的效果。     

Estimation of Nanoporous Au Young’s Modulus from Serial Block Face-SEM 3D-Characterisation

Nanoporous Au has been subjected to serial block face-scanning electron microscopy (SBF-SEM) 3D-characterisation. Corresponding sections have been digitalized and used to evaluate the associated mechanical properties. Our investigation demonstrates that the sample is homogeneous and isotropic. The effective Young’s modulus estimated by an analytical multiscale approach agrees remarkably well with the values stated in the literature.