基于非接触式测量的极短时心率变异性分析

目的实现基于成像式光电容积描记技术(iPPG)的心率变异性非接触式测量,并探讨极短时分析的可行性。方法使用高速摄像机拍摄12名男性受试者人脸视频,通过感兴趣区域提取,独立成分分析等方法得到与脉搏相关的iPPG信号,并进行了心率变异性的极短时分析。结果与心电信号相比,心率变异性的部分时域和频域特征具有较高的准确性和相关性:NNVGR和RMSSD的相关性最好,均在0.98以上,SDNN相关性在0.9左右;频域特征中,VLF、LF、HF的相关性均在0.8以上,pLF、pHF、LFHFRatio的相关性较低,且个体差异较大。结论iPPG技术可用于心率变异性的准确测量和监测,对于非接触条件下生理信号监测具有重要意义。     

基于FastICA与ICEEMDAN的人脸视频心率检测

现有的非接触式心率检测方法存在噪声干扰、准确率低等问题。针对这些问题,提出一种基于FastICA与改进的自适应噪声完全集合经验模态分解(ICEEMDAN)相结合的算法,采用人脸视频进行心率检测。用摄像头采集人脸视频,并从视频中提取R、G、B通道源信号,即皮肤颜色变化信号,分别求出RGB这3个颜色通道的像素平均值;然后利用 FastICA对RGB这3组像素平均值进行解混,得到3组独立源信号,再用ICEEMDAN将其中一组独立源信号进行模态分解,并选取合适频段内的固有模式函数(IMF)估计心率的信号,最后用频谱分析计算得到心率。设计实验对8名人员进行了人脸视频检测,将检测结果与多参数监护仪进行对比分析。实验结果表明,该方法与多参数监护仪测量结果的平均误差与均方根误差均小于1 beat/min,因此基于FastICA与ICEEMDAN的人脸视频心率检测对人体心率检测具有良好的稳定性和准确性。     

The effect of pain-related fear on sexual arousal in women with superficial dyspareunia.

The role of pain-related fear in the etiology and/or maintenance of superficial dyspareunia is still unclear. The objective of this experiment was to investigate the effects of pain-related fear on sexual arousal in women with superficial dyspareunia (n=48) and women without sexual complaints (n=48). To induce pain-related fear, participants were told that they had a 60% chance of receiving painful stimuli while being exposed to one of two erotic film clips. Genital arousal was assessed using vaginal photoplethysmography. Self-reported ratings of genital sensations and affect were collected after both erotic stimulus presentations. Elevated levels of skin conductance and higher ratings of experienced threat during the pain threat condition indicated that fear was successfully elicited. Pain-related fear impeded genital arousal in all women. Women of both groups reported significantly less positive affect and more negative affect when threatened. Although women with dyspareunia did not differ in their genital responsiveness from women without sexual complaints, they experienced overall significantly more negative affect than the control group. The present results indicate that pain-related fear reduces genital and subjective sexual responding in women with and without sexual problems.We conclude that emotional appraisal of the sexual situation determines genital responsiveness in both sexually dysfunctional and functional women.     

A comparison of non-invasive continuous finger blood pressure measurement (Finapres) with intra-arterial pressure during prolonged head-up tilt

Simultaneous intra-radial and non-invasive (Finapres, Ohmeda)blood pressures were compared during prolonged head-up tilt,in eight patients (mean age 49 years) with malignant vasovagalsyncope. Twelve tilts were performed, of which eight resultedin vasovagal syncope. The mean bias (difference between Finapresand intra-arterial pressures) for systolic pressure was +0.7mmHg (standard deviation 11.3 mmHg) and for diastolic pressurewas +5.4 mmHg (standard deviation 7 mmHg). The within-tilt precision(standard deviation of the bias) of the non-invasive measurementsvaried between 2.9–12.4 mmHg (median 4.5 mmHg) for systoliccomparisons, and 1.6–8.4 mmHg (median 4.4 mmHg) for diastoliccomparisons. In all but one tilt highly significant positiveincreases in both systolic (median 7.1 mmHg) and diastolic bias(median 81 mmHg) occurred on tilt with respect to resting pre-tiltlevels. Independent of the absolute level of agreement, thenon-invasive measurements followed changes in intra-arterialpressure closely, with 89% of beat-to-beat changes in systolicpressure, and 95% of beat-to-beat changes in diastolic pressurefollowed to within ±2 mmHg. This study suggests thatthe Finapres is well suited for use during diagnostic tilt testing,demonstrating an acceptable within-tilt precision and closelyfollowing pressure changes during vasovagal syncope.     

Non‐invasive monitoring of muscle blood perfusion by photoplethysmography: evaluation of a new application

Aim: To evaluate a specially developed photoplethysmographic (PPG) technique, using green and near‐infrared light sources, for simultaneous non‐invasive monitoring of skin and muscle perfusion. Methods: Evaluation was based on assessments of changes in blood perfusion to various provocations, such as post‐exercise hyperaemia and hyperaemia following the application of liniment. The deep penetrating feature of PPG was investigated by measurement of optical radiation inside the muscle. Simultaneous measurements using ultrasound Doppler and the new PPG application were performed to elucidate differences between the two methods. Specific problems related to the influence of skin temperature on blood flow were highlightened, as well. Results: Following static and dynamic contractions an immediate increase in muscle perfusion was shown, without increase in skin perfusion. Liniment application to the skin induced a rapid increase in skin perfusion, but not in muscle. Both similarities and differences in blood flow measured by Ultrasound Doppler and PPG were demonstrated. The radiant power measured inside the muscle, by use of an optical fibre, showed that the near‐infrared light penetrates down to the vascular depth inside the muscle. Conclusions: The results of this study indicate the potentiality of the method for non‐invasive measurement of local muscle perfusion, although some considerations still have to be accounted for, such as influence of temperature on blood perfusion.     

数字式脉搏血氧饱和度检测系统的研制

目的 研制脉搏血氧饱和度检测模块，可实时地对动脉血氧饱和度及心率进行连续无创地监测。方法 改变传统的以模拟技术为主要手段的处理方法，主要利用数字信号处理技术来完成一系列工作，使系统结构数字化，结果 经实验测试证明脉搏血氧饱和度检测模块结构简单，性能稳定，抗干扰性好，具有较高的准确性和重复性等特点。结论 该设计方案可行，它为脉搏血氧仪系统的数字化设计提供了一条新思路。