Natural frequency/damping coefficient relationship of the catheter-manometer system required for high-fidelity measurement of the pulmonary arterial pressure

Using a digital simulation method, we analyzed the relationship between natural frequency (f _n ) and damping coefficient () of the catheter-manometer system required for high-fidelity measurement of the pulmonary arterial pressure. The pulmonary artery pressure waveform was obtained with a catheter-tip transducer and it was fed into a dynamic simulator programmed on a computer. The original waveform and the output of the simulator were compared and judged visually for the fidelity. From this analysis, the combination of f _n and was obtained and was plotted on a f _n – diagram. It showed as an area, which was convex on the left side and open on the right side. The left-convex endpoint was located at a damping coefficient of about 0.7. At a lower heart rate, this area was extended to the lower frequency side, while, at a higher heart rate, this area was limited to the higher frequency side. The f _n – diagram was also constructed theoretically by calculating the relations between natural frequencies and damping coefficients of a second order system with the amplitude and phase error tolerance set at +/–5% respectively.(Kinefuchi Y, Suzuki T, Takiguchi M, et al.: Natural frequency/Damping coefficient relationship of the catheter-manometer system required for high-fidelity measurement of the pulmonary arterial pressure. J Anesth 7: 419--426, 1993)     

The human motion onset VEP as a function of stimulation area for foveal and peripheral vision

We studied amplitude of the wave N200 of the motion-onset VEP by varying the side length of a square stimulation field between 0.5 and 7 degrees. A significant increase in amplitude was obtained between 0.5 and 1 degree of side length in central stimulation and between 0.5 and 5 degrees in 10-degree peripheral stimulation. Variations of spatial frequency between 0.34 and 6.8 c/deg did not modify the amplitude size, ie, no tuning effect could be found. The results of simultaneous and separate stimulation of foveal and parafoveal regions support the observation that the stimulation field size is a minor influence. Features of motion-sensitive cortical neurons, such as those found in monkeys, could account for this behavior.     

Variability of the steady-state visually evoked potential: Interindividual variance and intraindividual reproducibility of spatial frequency tuning

At low contrast levels there is good agreement between the psychophysical contrast sensitivity function and the tuning curve of the visually evoked potential (i.e., VEP amplitude vs spatial frequency). At high contrast, however, some researchers have found bimodal VEP tuning curves whereas others have not. We studied the VEP in 22 subjects in a short-term cross-sectional study and in 13 subjects in a longitudinal study over 8 sessions covering 28 days. Grating stimuli with 60% contrast were square-wave modulated in time (7.8 reversals/s) and space (0.06–16 cycles/degree). We found large interindividual variance in the shape of the tuning curves; about half of the subjects showed a unimodal shape, while the other half showed a bimodal one (with a notch between 1 and 2 cycles/degree). These features turned out to be stable in the longitudinal study, where variability could mainly be ascribed to a multiplicative influence common to all spatial frequencies. The marked interindividual differences in the shape of the tuning curve, which seem to be intraindividually stable, may explain previous discrepancies. It is not yet clear why the notch exists in about half of our subjects.     

Determination of trace selenium in human body by anodic stripping voltammetry at gold-disc electrode

Summary For determination of trace Se we used high-pressure wet digester to pretreat the specimens obtained from the human body. This method is very effective in preventing loss of Se by volatilization which often occurs in the sample pretreatment. We studied the method of using anodic stripping voltammetry at gold-disc electrode to measure the trace Se present in the human body and found it to be the optimal procedure. The detection limitation was about 2x10⁻⁸ g/L, the recovery rate of Se about 96.6±6,7 % , and the coefficient of variation CV = 7.0%.     

Therapeutic effects of radio frequency ablation in lung tumor treatment

Radiofrequencyablation(RFA)isarecentlyde-velopedsystemthatprovidesanewapproachforthetreatmentofpatientswithunresectablemalignanttu-mor.Aninsulatedneedleelectrodethatcontains10fineneedleswithinentersthetumortissueunderCTguidanceandthe10fineneedlesstretchasanumbrel-lacoveringanareaapproximately3.5cmindiameter,beforearadiofrequencygeneratortransmitshigh-en-ergyradiofrequencypulsesthroughthewiretothefineneedles.Theenergyreleasedattheneedlepointcantriggerionicagitationandfrictionalheattopro-ducea…     

14例中小肝癌射频消融治疗的近期疗效分析

目的 探讨射频消融治疗中小肝癌（直径≤5cm）的疗效。方法 应用可扩张的集束电极对14例中小肝癌共18个病灶进行射频消融治疗,观察其治疗过程中的反应、治疗时间、治疗次数、影像学表现以及治疗前后的肝穿刺病理结果,并随访观察其复发和生存情况等。结果 14例中小肝癌的治疗次数为1～2次,平均治疗时间为50min;治疗后的反应包括伤口自限性出血、转氨酶升高、肝区疼痛及发热等;治疗后对9例病灶行多点穿刺活检均为凝固性坏死及纤维组织;CT扫描显示治疗后病灶扩大,但无明显强化,3个月后病灶开始缩小,病灶完全坏死率为93%;经12～18个月的随访,全部病例存活。结论 射频消融治疗中小肝癌具有创伤小、并发症少、效果确切等优点,可望成为治疗中小肝癌的有效方法之一。     

广西汉族人群DIS80位点基因频率分布调查

采用PCR技术结合聚丙烯酰胺凝胶电泳及银染检测法 ,对 15 0名广西地区汉族无关个体进行DIS80位点的VNTR扩增片段长度多态性分析。结果检出 2 1个等位基因 ,6 3个基因型 ,杂合度、个体识别力和基因频率分布为 0 .873、0 .973、0 .0 0 3～ 0 .190。其基因频率分布符合Hardy -weinberg定律 ,对 3个家系相关个体分析符合孟德尔定律。提示DIS80位点为高度多态的遗传标记 ,在个体识别、群体遗传等方面均有重要的应用价值     

穴位体表电刺激对术后PCEA的强化效应

目的　观察穴位体表电刺激对术后患者硬膜外自控镇痛（PCEA）效果、镇痛药用量、血清皮质醇浓度和不良反应的影响。方法　 选择经腹全宫切除术患者40例（ASAⅠ～Ⅱ级）,随机分成二组,每组20例。A组：于术后第4,8小时 Han's各刺激30 min,术后行PCEA。B组：单纯行术后PCEA（对照组）。术后随访镇痛效果、镇静评分、布氏舒适评分（BCS）,分段记录24 h镇痛药用量及总按压次数/实进次数（D1/D2）比值,血清皮质醇含量,肛门恢复排气时间和不良反应情况。结果　两组镇痛效果满意,A组BCS评分高于B组（P＜0.05）。A组镇痛药用量为（31.7±1.9）ml,与对照组（34.2±2.1）ml相比差异有显著性（P＜0.01）。血清皮质醇浓度两组均较术前下降,但A组术后8 h的下降幅度大于对照组。A组恢复肛门排气时间快于B组,而且恶心、呕吐与对照组相比有所减少。结论　术后患者硬膜外腔自控镇痛（PCEA）复合应用穴位体表电刺激,可增强镇痛效果,减少用药量,降低不良反应,是安全有效的复合镇痛方法。     

计算机辅助的心血管信号检测和处理系统的研究

【目的】研制一个计算机辅助的心血管信号检测和处理系统。【方法】本系统的硬件设计采用奔腾 Ⅱ / 2 33多媒体微机系统 ,多路模 /数转换器和心电电极、心音传感器、脉搏波传感器及由运算放大器等构成相关的放大器及滤波器。本系统采用可视化编程环境构建系统结构和功能模块设计的方法 ,基于多媒体技术和小波变换原理 ,在 32位Windows平台下 ,利用可视化编程语言VisualC 6 0和多媒体著作工具Authorware等进行系统的软件设计。【结果】本系统能完成心电、心音、脉搏波信号检测和处理 ,并将结果以图、文、声并茂的形式显示、打印或播放 ,还具有病案管理和心音听诊多媒体计算机辅助教学功能。【结论】它是一个新型的多功能心血管信号检测和处理系统。     

短声作为刺激声进行同侧声反射阈测定之临床价值

目的 :确定短声可代替纯音作为刺激声作同侧声反射阈测定 ,并了解探测音频率对声反射阈的影响。方法 :应用 GSI33 型中耳分析仪 ,对正常志愿者 2 3例 46耳作不同探测音频率的纯音及短声刺激率 10 0次 / s及180次 / s的同侧声反射阈测定。结果 :声反射阈 2 2 6 Hz探测音时 5 0 0 Hz、10 0 0 Hz、2 0 0 0 Hz分别为 ( 84.35±6 .96 ) d B、( 84.6 5± 5 .93) d B、( 87.96± 6 .36 ) d B;6 78Hz探测音时分别为 ( 93.13± 6 .5 4) d B、( 92 .70± 6 .33) d B、( 93.35± 5 .99) d B;10 0 0 Hz探测音时分别为 ( 86 .5 2± 4.72 ) d B、( 87.48± 5 .0 0 ) d B、( 88.30± 6 .16 ) d B。短声刺激率 10 0次 / s及 180次 / s同侧声反射阈 2 2 6 Hz探测音时分别为 ( 89.78± 6 .83) d B、( 92 .0 7± 7.42 ) d B;6 78Hz探测音时为 ( 90 .44± 6 .76 ) d B、( 90 .6 5± 6 .38) d B;10 0 0 Hz探测音时为 ( 88.0 4± 6 .87) d B、( 88.6 9± 7.49) d B。 6 78Hz探测音 ,声反射阈高于 2 2 6 Hz及 10 0 0 Hz。结论 :低刺激率的短声作为刺激声并未出现赝象 ,可作为进行同侧声反射阈测试的刺激声