Medical progress through technology最新文献

Unlabelled: Acceleration plethysmography (APG) uses the second derivative of the waveform of the digital photoplethysmography to stabilize the baseline and to separate components of the waveform more clearly than the first derivative. The purposes of this study were 1) to investigate the association between APG and aging, using our new criteria of four patterns and 2) to test the clinical usefulness of APG for the prediction of the level of atherosclerosis. The examined subjects were 82 males and 308 females aged 30-69 years. Plethysmograms were recorded in the sitting position. We compared the distribution of four patterns of APG by age group and analyzed the predictor of changing waveforms. We also analyzed the association between wave patterns and the risk factors, i.e. total cholesterol (TC), high density lipoprotein cholesterol, systolic blood pressure, diastolic blood pressure, body mass index, and current smoking status.

The results: -categorized four wave patterns were significantly associated with aging; -pulse pressure (PP), body height and sex influenced waveforms of APG independently of age; and -categorized wave patterns were associated with high serum TC among risk factors for atherosclerosis. Those results suggest that APG reflects the arterial wall properties which change with age and might predict the level of atherosclerosis. To provide further guidance for determining appropriate clinical interpretations of APG, it is required to consider the effects of PP, body height and sex. We conclude that simply categorized wave patterns of APG could be a useful noninvasive tool to evaluate aging in cardiovascular system.

We examined a large population of patients undergoing temporomandibular joint (TMJ) surgery and provide a documentation of the average patient population, frequency of procedures, frequency of repeat procedures, and trends in open (arthrotomy) versus closed (arthroscopy) TMJ surgery. Data on 194 TMJ surgical procedures was extracted from line item claims information collected by Trigon Blue Cross/Blue Shield of Virginia. The frequency of arthroscopy increased during the study, while the incidence of arthrotomies remained relatively low. Approximately half of the hospitals statewide did not perform either procedure. There was a low frequency (3%) of repeat procedures. In the Commonwealth of Virginia, since the advent of TMJ arthroscopy, it has become the preferred surgical technique for treatment of internal derangement. There is a low incidence of repeat procedures for both types of treatment. Analysis of insurance carrier computer records is a valid technique for evaluating trends in surgical care.

The sonogram outputs of autoregressive (AR) based spectral analysis of a 20 MHz pulsed ultrasonic Doppler blood flowmeter are presented. The data obtained from coronary and iliac arteries were processed using AR-based spectral analysis technique, and then the interpretable sonograms by the surgeons were constructed. When the sonogram outputs were compared to other sonograms which were analysed using the other techniques such as fast Fourier transform (FFT), it was observed that AR-based sonograms for 20 MHz pulsed Doppler data have provided better results. Therefore, the technique is strongly recommended in the examining of small vessels which are 1 to 2 mm in diameter.

Stroke is unique among neurological diseases since it has a high incidence rate, severe burden of illness, high economic cost, and it may be preventable [1]. Described here is a system for screening the cerebral and vascular status of individuals to detect the initial stages of vascular disorders. The computer based polygraphic system (CERBERUS) questions subjects about risk factors, stresses, neurologic symptoms and monitors impedance pulse waves of the head and extremities, EEG, and ECG. The system has been tested in 691 cases. Doppler control studies were carried out on approximately 300 of these cases. Additional somatic measures and psychological tests related to stroke risk factors were carried out for wide biological basis of possible correlation of CERBERUS data base. The high incidence of cerebrovascular disturbance was established by CERBERUS data, further confirmed by additional data gathered, and moreover was compared by traditional medical records. The polygraphic system is more sensitive at detecting physiological asymmetries of blood flow than even a Doppler measurements. This suggests that it may be a significantly improved means for the differential diagnosis of neurological disease and the screening of subjects for arteriosclerosis, transient ischemic attack and stroke prevention to be offered at the lowest level of medical service.

Tactile stimulation is a means of transferring information to visually handicapped individuals. A study of the power delivered by the driving waveform to a transducer used for tactile stimulation as a function of the parameters of the waveform is presented. The power delivered within the region of maximum tactile skin sensitivity, Qfw, is compared to the total power delivered by the waveform in one cycle, PT, as a function of the waveform parameters with the objective of finding the parameters that would maximize the ratio Qfw/PT. In this study, the driving waveform is composed of an excitatory period followed by a recovery time. The excitatory period is formed by a burst of rectangular pulses modulated in amplitude by different waveforms. After a Fourier decomposition of the excitatory waveform, the contribution of each harmonic was added to compute the power delivered within the frequency region of interest. Additionally, to take in account the contribution of each harmonic in the overall tactile sensation, the power delivered within the region of maximum tactile skin sensitivity was weighed by the skin tactile sensitivity function and then linearly summed. The results show that the ratio Qfw/PT has a maximum for pulse widths between 0.8 and 1.2 ms for all pulse frequencies in the range 50-700 Hz when the tactile sensitivity function was not considered. The optimum pulse width, when the tactile sensitivity weighing function is considered in the computations, was in the range between 0.7 and 1.7 ms for pulse frequencies between 50-700 Hz. The ratio Qfw/PT is invariant to changes in the number of pulses per burst and the length of the recovery time. Once the tactile system frequency response is identified, all the waveform parameters can be specified for maximum power targeted to the region of maximum tactile sensitivity.

To prepare the long-life and stable glucose sensor, we developed the ferrocene-mediated needle-type glucose sensor covered with newly designed biocompatible membrane, 2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate (MPC-co-BMA) membrane. In this membrane, the hydrophilic phosphorylcholine chains were grafted on the hydrophobic polymer surface. 1. The poly(MPC-co-BMA) membrane inhibited platelet activation and protein adhesion on the surface, showing excellent biocompatibility. These results suggested that the hydrophilic phospholipids chains might have the potential for suppressing activation and adsorption of biochemical molecules. 2. The ferrocene-mediated needle-type glucose sensor covered with poly(MPC-co-BMA) membrane achieved excellent results in vitro. Subcutaneous tissue glucose concentrations were measured in a wide range from 1.7 to more than 16.7 mmol/l. The correlation between subcutaneous tissue (Y) and blood (X) glucose concentrations was Y = 1.04X + 0.12 (r = 0.98). The subcutaneous tissue glucose concentrations could be monitored precisely for 7 days without any in vivo calibrations, and for 14 days by introducing in vivo calibrations. We therefore conclude that this sensor is stable and reliable, as compared to any other glucose sensors we developed.

We have studied skilled human locomotions in sports gymnastics by measurement and analysis of ground reaction force and myoelectric signals. Assuming the quality of performance to be a skill level criterion acquired signals were mathematically analyzed via basic signal processing and cross-correlation methods. The study of backward somersault yielded quantitative criteria of performance, proposing an original measure-an inter-muscular cross-correlation function. Besides motor learning, the quantification of movement skill introduced here also relates to possible applications in biocybernetics, robotics and rehabilitation medicine.

This is the largest retrospective analysis of biliary tract surgery ever reported involving 6,378 patients operated on during a three year period, 1990-1992. During this time interval, the frequency of laparoscopic procedures has increased dramatically. The use of laparoscopic procedures was associated with a significant decrease in the total length of hospital stay and total charges as compared to the open procedures. Because of laparoscopic surgery's increased acceptance, we propose that the frequency of laparoscopic surgery of the biliary tract should be used as a quality control measure.

The complex permittivity of dehydrated bovine femoral bone has been studied in vitro, in the three orthogonal directions from 1 kHz to 3 MHz, as part of an analysis of the various factors involved in the dielectric behavior of fluid-saturated cortical bone. In this study the bone's physical structure reveals its anisotropic nature by its dependence on both the real and imaginary parts of permittivity on the orientation of the applied electric field. The real permittivity and the total conductivity are generally higher in the longitudinal direction than in the other two transverse directions, with the tangential direction presenting values between those of the longitudinal and radial directions and closer to the former. The high frequency limit of the real part of the permittivity was found to be around 10 and its low frequency limit is of the order of 1000. The dispersion parameters of relaxation time show values of about 0.4 and the corresponding mean relaxation frequencies are below 100 Hz.