The SmartDrive console represents an important advance in small bone surgery because it monitors and coordinates the operation of its handpieces. The SmartDrive console has the following unique features: 1) a handpiece recognition system; 2) an instrument speed display; 3) a handpiece display and monitoring system; 4) a torque instrument control system; 5) a temperature monitoring system; 6) and an irrigation system. Mechanical performance studies have been undertaken that have validated the accuracy of the monitoring systems of the consoles. The consoles provided reliable recordings of the rotational speeds of their hi-speed drills. The MicroAire console automatically shuts off its power as the temperature increased to 110 degrees F (43 degrees C). In contrast, the Stryker Command 2 console has a limited monitoring system that can not alter the operation of the handpieces.
Knowledge about the viscoelastic behaviour of the arterial wall has been proved to have physiological importance and clinical usage. Our purpose was to study the changes of the systemic arterial wall's elastic properties non-invasively, in patients with established essential and with borderline hypertension, and to evaluate its possible determinants. Three groups of normotensive, borderline and established essential hypertensive patients were evaluated. Arterial pulse wave velocity (PWV) was measured and arterial compliance (Cm) was derived in all patients. Pulse wave velocity was obtained from the pressure values of digitized carotid and radial arteries. Arterial compliance (Cm = dD/dP with P pressure and D diameter) was calculated using a formula derived from the Bramwell and Hill equation: Cm = (1,334 x D)/(2 rho x PWV2), where for D humeral diameter was used as measured by high resolution echograph, and rho is the blood density (rho = 1.06). Pulse wave velocity was significantly higher in established essential hypertensive patients with respect to normotensive patients (p < 0.05). Arterial compliance was significantly diminished in established and in borderline hypertensive patients with respect to normotensive patients (p < 0.05), which implies early alterations in hypertensive cardiovascular disease. Multiple regression analysis of the cofactors showed that age and diastolic pressure are independent determinants of Cm. Impairment of the arterial wall's intrinsic elastic properties was demonstrated in established essential hypertension, independent of age and diastolic pressure.
The electrically evoked potential in the auditory nerve is measured when the cochlear is stimulated with a high density electrode array whose microcontacts (20 x 160 microns) are placed close to the nerve cells. Threshold range from 8 to 35 microA with the stimulating electrodes near the spiral ganglion cells. A multi-pole technique for restricting the spread of current with electrical stimulation of the cochlea is tested using neural recording in deafened guinea pigs. The ground based quadrupolar electrode driving configuration has thresholds for neural activation only slightly greater than monopolar stimulation when the electrode contacts are placed less than 50 microns from the neurons. During simultaneous stimulation the monopole and the ground based quadrupolar modes tend to generate similar growth functions (magnitude and latency). The electrode interactions are generally factorial, which means that the algebraic sum of the responses (magnitude growth functions) produced by 2 distinct electrodes is less than when the same 2 electrodes are stimulated simultaneously.
The human body is a medium which consists of various tissues such as skin, fat, muscle and bone. Each of the tissues has their own biomechanical properties. We have measured biomechanical impedances by applying a random vibration (30-1000 Hz) to the layered model of human tissues to study the occurring mechanism of impedances measured at the skin surface. The data showed that the top tissue layer and the underlying layer both contribute to the impedance depending on the thickness of the top layer. The contribution of the underlying layer was clearer over the frequency range from 30 to 400 Hz. Quantitatively we found the following: The impedance measured at the surface was roughly expressed as the model which is connected in series by the impedances of the top and underlying tissues. The contribution of the underlying tissue decreased according to the increase of the thickness of the top tissue, and disappeared over a certain thickness (18 mm in this paper).
A reasoning method to explicate the conclusions - a posteriori - and to prospect for the next test - a priori applied to medical expert systems based on fuzzy analog ganglionar lattices is presented. This method is founded on the sensitivity criterion of the consequent respect to the antecedents. It proves to be suited for problems of any complexity specially when they are formulated on well-established intermediate concepts, such as syndromes, clinical finding, laboratory procedures, etc., as is usually the case in medical procedures. This type of expert system uses the structural properties of the ganglionar lattice to produce explications for its conclusions at different levels of abstraction, and to an arbitrary, but fixed, explicative degree. A measure to evaluate the consequent's achieved preciseness (certainty) is also supplied. A full example of application in the diagnosis of cardiac insufficiency with hypertensive myocardiopathy is shown, and a computational implementation of this analog procedure is described. Finally, the reasoning methods for explicating and prospecting are discussed.
UNLABELLEDAcceleration 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.
The purpose of this study was to perform a biomechanical performance study and a clinical trial on a new external condom catheter system. The biomechanical performance study demonstrated that the vented connector failed following exposure to urine for 14 days. In addition, angulation of the inlet adapter of anti-reflux valve of the urinary leg bag to an angle of 35 degrees (+/-5 degrees) caused complete obstruction of urinary flow. A clinical trial of the new condom catheter with its inner flap revealed twisting of the catheter that interrupted urinary flow in four of ten patients. This catheter twisting was not observed in condom catheters without inner flaps. Furthermore, this new system is not easily applied or removed by patients with neurosensory deficits or musculoskeletal weakness. Design modifications of the vent within the connection tubing, the anti-reflux valve in the collection bag, the condom catheter with its inner flap, as well as the leg bag attachments should remarkably improve the performance of this new urinary drainage 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 lack of depth perception hampers the surgeon during laparoscopic operation. Laparoscopes usually are monocular, but binocular ones are currently available. Depth perception, however, does not exclusively rely on binocular disparity. An observer, with only one eye, who is able to move that eye, obtains the same information as an observer who has two eyes. This principle of movement parallax can be applied to laparoscopy by coupling the head movements of the surgeon to the motions of the tip of the laparoscope. In an experiment we investigated if this principle is applicable to laparoscopy. Two groups of testees with no background in surgery were used. The first group was assisted by movement parallax, the second group was viewing a static image. Both groups of testees had to perform an exploration and a manipulation task. Since the amount of space for camera motion within the laparoscope is limited, implementation potential depends on the amount of movements that will be made by the observer. Therefore the movements of the observer performing the exploration task were registered and analysed. Results of the experiment indicate the advantage of movement parallax for the exploration task (performance increases by factor 2 while using only 30% more time) but not for the manipulation task. The analysis of the movements indicates that small movements are sufficient for implementation. Based on these results we concluded that movement parallax is applicable to laparoscopy.
NiTi alloy specimens were plasma cleaned and then coated with a thin film of plasma-polymerized tetrafluoroethylene (TFE) in a Radio-Frequency reactor. The corrosion protection provided by these films was studied by potentiodynamic tests performed in Hank's physiological solution. Surface properties which determine biocompatibility were characterized by X-ray photoelectron spectroscopy (XPS). The results showed that the surface of untreated NiTi was mostly composed by oxygen, carbon, titanium oxide (TiO2) with traces of nickel oxides (NiO and Ni2O3) and metallic Ni. The passivity of untreated NiTi was found to be unstable in the simulated human body media. After plasma treatment, the NiTi surface contained only carbon and fluor. The plasma-polymerized thin film was found to stabilize the NiTi passivity and to increase its pitting potential. This treatment provides a good protection against dissolution of nickel from NiTi alloys.
The accuracy of the radiology vocabulary domain of the IBM VoiceType Dictation for Windows speech recognition system for use in a clinical setting was evaluated. Six men and one woman dictated a case report under several conditions. The impact of vocabulary domain, microphone position, personal enrollment, and background noise were assessed. The dictations were exported to Microsoft Word 6.0, printed, and graded for accuracy. The data were expressed as a percentage correct. The enrollment and training processes took an average of 5 hours to complete. The accuracy of VoiceType Dictation was significantly reduced by speech volume and background noise level so that it could not be used to dictate clinical information accurately in a hospital setting. Although IBM's VoiceType Dictation with the radiology vocabulary domain has improved speech recognition, it is not a reliable dictation system for accurate and efficient clinical dictation in a hospital setting.
A new communication channel for severely handicapped people could be opened with a direct brain to computer interface (BCI). Such a system classifies electrical brain signals online. In a series of training sessions, where electroencephalograph (EEG) signals are recorded on the intact scalp, a classifier is trained to discriminate a limited number of different brain states. In a subsequent series of feedback sessions, where the subject is confronted with the classification results, the subject tries to reduce the number of misclassifications. In this study the relevance of different spectral components is analyzed: 1) on the training sessions to select optimal frequency bands for the feedback sessions and 2) on the feedback sessions to monitor changes.
This is the largest retrospective analysis of sinus surgery ever reported involving 5,860 surgical as well as 6,769 diagnostic sinus procedures during a six year period, 1988-1993. During this time interval, the frequency of endoscopic procedures has increased dramatically. Because of the increased frequency of this procedure, we see the need for strict definition of the clinical indications for surgery for patients with chronic or acute sinusitis. In addition, the number of open procedures, namely the Caldwell-Luc procedure, as a treatment for sinusitis remained relatively constant despite the frequent use of endoscopic technique. Because of the endoscopic surgery's increased acceptance and advantages over the open surgical technique, we emphasize the need for continuing educational programs to train surgeons to perform the endoscopic procedure or referral of the patient to an otolaryngologist experienced in this technique.
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.
This study deals with methods focused on estimating blood velocity. The estimation of the linear trend function of a non-stationary signal based on the adaptive recursive estimation of the mean value function is used for the determination of the time delay of two indicator dilution curves. The filter property of this trend operator depends on the choice of a constant parameter c, the so-called adaptation factor. The functional connection between the filter property and the adaptation factor is considered in such a way that an objective calculation of arterial blood velocity in retinal vessels is possible.
Electric field plethysmography (EFPG) signals of the human thorax consist of a baseline component, a respiratory component and a cardiac component. This paper investigates to what extent a two-dimensional finite-element model of the human thorax can serve as a tool for signal prediction allowing for both optimisation of electrode position and effective signal interpretation. In the model inspiration is taken into account by decreasing lung conductivity. Modelling of cardiac activity involves heart geometry changes and lung conductivity increase. Comparison with experiments shows that the model is more effective for strip than spot electrodes for current injection. Modelling results suggest that the thorax behaves approximately as a homogeneous structure with an inspiratory conductivity increase of about 5%. Two electrode pairs are preferable for monitoring respiration in general. As cardiac activity involves two counter-acting signal sources in the thorax, optimum electrode position is obtained using four separated electrodes. However, recommendable positions for two electrode pairs are on the left sternal and right parasternal line. The investigation shows that in providing a proper modelling of respiration and cardiac activity, a 2-D model provides a practical tool for modelling EFPG signals with the cost of a few structural and systematical restrictions.
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.
Colors in video representations of angioscopic images are up until now described by an human observer. Differences in settings of the monitor and the inherent poor ability of the human eye to classify colors objectively results in a very poor intraobserver as well as interobserver variability. A PC-based method is described to measure colors in a video image and to present the results in a novel C-diagram. Results with this method for standard calibrated colors are given. Possible sources of error are discussed and methods to minimize these errors are presented.
This work presents an Expert System based on fuzzy analog ganglionar lattices. Its reasoning scheme is designed analogously to the expert's mental organization and it is realized on an (analog) operator called the ganglionar lattice. It is a connectionist system that uses the medical knowledge to define its architecture. The operator evokes some similarities to higher order neural networks and performs as the knowledge base and inference engine of the expert system, in a unified manner. A main feature of this operator is that it exhibits the variables corresponding to all intermediate concepts identified by the expert; this characteristic is shown to be most valuable for assessing, explicating and prospecting in medical applications. Further, it is capable of (i) evaluating a consequent for a variety of non-approximate reasonings with multiple antecendents of different relative importance under limited uncertainty; (ii) explicating the conclusions at different levels of abstraction to suit the user; and (iii) prospecting for the best 'a priori' sequence of unevaluated antecedents, from which to choose following tests. These procedures are based on the objective criterion of the consequent's uncertainty decrease (entropy). All results are produced in numerical form and may be translated into restricted natural language. A simple example of this technology is fully developed. Finally the method's potentials are discussed for future applications.
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.
