听觉诱发电位指数、脑电双频指数及心血管反应评估"过浅麻醉"的价值

目的通过研究丙泊酚诱导过程中,听觉诱发电位指数(AAI)、脑电双频指数(BIS)及心血管反应与插管体动的关系,探讨上述监测手段是否能够反映“过浅麻醉”。方法35例ASAⅠ~Ⅱ级妇科择期手术患者,以丙泊酚进行诱导,患者入睡后,用压力袖带隔离一侧前臂,静注维库溴铵0·1mg/kg。当丙泊酚靶控输注(TCI)达到设定血浆靶浓度(3·5μg/ml)后行气管内插管。记录隔离侧手臂运动(体动)情况,并以是否发生体动反应为准将患者分为体动组与非体动组。记录患者诱导前、插管前的SBP、DBP、HR、BIS、AAI及插管后2min内上述指标的最大值。结果体动组AAI插管后明显高于插管前(P<0·01),而非体动组插管前、后的差异无显著意义;两组患者BIS插管前、后组内及组间的差异均无显著意义;插管引起的DBP、SBP增高体动组明显大于非体动组(P<0·01),但HR变化两组相似。结论BIS仅是衡量睡眠深度的指标,AAI及BP反映“过浅麻醉”,反映机体对伤害性刺激的反应较BIS敏感。     

Five-year mortality in patients with diabetic foot ulcer during 2009–2010 was lower than expected

AimMortality rates are decreasing in patients with diabetes. However, as this observation also concerns patients with diabetic foot ulcer (DFU), additional data are needed. For this reason, our study evaluated the 5-year mortality rate in patients with DFU during 2009–2010 and identified risk factors associated with mortality.MethodsConsecutive patients who attended a clinic for new DFU during 2009–2010 were followed until healing and at 1 year. Data on mortality were collected at year 5. Multivariate Cox proportional-hazards model was used to identify mortality risk factors.ResultsA total of 347 patients were included: mean age was 65 ± 12 years, diabetes duration was 16 [10; 27] years; 13% were on dialysis; and 7% had an organ transplant. At 5 years, 49 patients (14%) were considered lost to follow-up. Total mortality rate at 5 years was 35%, and 16% in patients with neuropathy. On multivariate analyses, mortality was positively associated with: age [hazard ratio (HR): 1.05 (1.03–1.07), P < 0.0001]; duration of diabetes [HR: 1.02 (1.001–1.03], P = 0.03]; PEDIS perfusion grade 2 vs. 1 [HR: 2.35 (1.28–4.29), P = 0.006)]; PEDIS perfusion grade 3 vs. 1 [HR: 3.14 (1.58–6.24), P = 0.001); and ulcer duration at year 1 [HR 2.09 (1.35–3.22), P = 0.0009].ConclusionMortality rates were not as high as expected despite the large number of comorbidities, suggesting that progress has been made in the health management of these patients. In particular, patients with neuropathic foot ulcer had a survival rate of 84% at 5 years.     

异氟醚麻醉深度的多指标微机实时判断

目的：编制一套多指标监测、微机统计和评分程序，用于术中随时判断麻醉深度。方法：手术病人３２例，１５项指标同时监测，当需要判断麻醉深度时，输入全部指标值，微机计算出总分值（Ｍ），根据Ｍ的增减来判断麻醉深度的相对变化。为验证Ｍ的可靠性，测定血浆环磷酸腺苷浓度，计算二者的相关性。结果：其中２２例的Ｍ与ｃＡＭＰ的个体相关系数（ｒ）的均值为０．８１±０．０８，有显著意义（Ｐ＜０．０５）。结论：本研究拟订的评分法能在７０％的病人中较准确地判断麻醉深度，尤其显示微机判断的实时性。     

Quantitative perceived depth from sequential monocular decamouflage

We present a novel binocular stimulus without conventional disparity cues whose presence and depth are revealed by sequential monocular stimulation (delay > or = 80 ms). Vertical white lines were occluded as they passed behind an otherwise camouflaged black rectangular target. The location (and instant) of the occlusion event, decamouflaging the target's edges, differed in the two eyes. Probe settings to match the depth of the black rectangular target showed a monotonic increase with simulated depth. Control tests discounted the possibility of subjects integrating retinal disparities over an extended temporal window or using temporal disparity. Sequential monocular decamouflage was found to be as precise and accurate as conventional simultaneous stereopsis with equivalent depths and exposure durations.     

The visual perception of plane tilt from motion in small field and large field: psychophysics and theory

Subjects indicated the tilt of dotted planes rotating in depth, in monocular viewing, under perspective projection. The responses depended on the FOV (field of view) and on the angle W between the tilt and frontal translation (orthogonal to the rotation axis). Response accuracy increased with the FOV, and decreased with W. Our results support the processing of the second-order optic flow in all cases, but indicate that this flow is quantitatively small in small-field, leading to tilt ambiguities. We examine computational models based on the affine components of the optic flow to interpret our results.     

Neural correlates of monocular and binocular depth cues based on natural images: a LORETA analysis

Functional imaging studies investigating perception of depth rely solely on one type of depth cue based on non-natural stimulus material. To overcome these limitations and to provide a more realistic and complete set of depth cues natural stereoscopic images were used in this study. Using slow cortical potentials and source localization we aimed to identify the neural correlates of monocular and binocular depth cues. This study confirms and extends functional imaging studies, showing that natural images provide a good, reliable, and more realistic alternative to artificial stimuli, and demonstrates the possibility to separate the processing of different depth cues.     

Evidence for elongated receptive field structure for mechanisms subserving stereopsis

To study the spatial extent and shape of the binocular disparity mechanisms subserving depth perception, we employ the spatial summation paradigm of contrast threshold for front/back depth discrimination at a fixed binocular disparity. The stimuli were Gabor patches with disparity set at either 4 or 8 arcmin and spatial frequency set at an optimal value of 4 cy/deg. Contrast threshold was measured as a function of length and width of the Gabor patches to determine the aspect ratio of greatest efficiency. The space constant of the Gaussian envelope varied between 0.0375 degrees and 0.9 degrees in either vertical or horizontal directions, or both simultaneously. For vertical elongation of the Gabor patches, discrimination sensitivity improved by 4-6 dB for a doubling of the length of the Gabor patches, then reduced more slowly as the length further increased. However, extending the Gabor patches horizontally across cycles produced little or no sensitivity improvement. Instead, discrimination performance collapsed in a fashion that is incompatible with many models of disparity processing. The results imply that the main mechanisms subserving stereoscopic depth discrimination are vertically elongated for vertical-bar Gabors and encounter special difficulties integrating horizontal disparity information. Disparity discrimination sensitivity for very small targets was also much greater than predicted by the single-mechanism fit, implying the presence of a second, independent mechanism with a very small summation field, which may underlie the fine stereoscopic processing system.     

Stereoscopic depth discrimination with contrast windowed stimuli

Depth discrimination with a shifted contrast window was compared to that with a fixed contrast window. Stereoscopic performance with the fixed window was limited to small disparities and varied with spatial frequency. Performance with the shifted window extended to larger disparities and was more similar for low and high spatial frequencies. The results depended upon window shape, indicating that edge blur is an important factor. Stereoscopic performance with shifted patterns was supported at disparities larger than a phase disparity model might predict, suggesting that a combination of position and phase disparity computations are used for the perception of stereoscopic depth.     

3D shape discrimination using relative disparity derivatives

Three-dimensional (3D) shape discrimination could be achieved using relative disparity signals or it could be achieved using a higher-order disparity derivative detector. Two 3D shape discrimination tasks were used to distinguish between these possibilities: a within-shape task and a between-shape task. Disparity thresholds were larger when discriminating within the same shape than when discriminating between shapes. More importantly, within-shape discriminations were dependent on the pedestal disparity (distance from fixation) whereas between-shape discriminations were not. The results suggest that a mechanism sensitive to higher-order disparity derivatives can achieve discrimination between different 3D shapes.     

Differential localization in dorsal funiculus of fibres originating from different receptors

Summary The cervical part of the dorsal funiculus in the cat was investigated by recording from single fibres and by recording of mass activity in dissected fascicles. It is demonstrated that large myelinated fibres originating from different receptors ascend at different depths of the funiculus. Fibres from hair and claw receptors occupy the superficial part of the funiculus and fibres from touch and vibration receptors the deep part. Fibres from muscle receptors occur at an intermediate depth of the funiculus. A large number of synaptically activated fibres ascend in the deep part.