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PubMed2004

Enhanced quality and quantity of retrieval of Critically Appraised Topics using the CAT Crawler.

As healthcare moves towards the implementation of Evidence-Based Medicine (EBM), Critically Appraised Topics (CATs) become useful in helping physicians to make clinical decisions. A number of academic and healthcare organizations have set up web-based CAT libraries. The primary objective of the presented work is to provide a one-stop search and download site that allows access to multiple CAT libraries. A web-based application, namely the CAT Crawler, was developed to serve physicians with an adequate access to available appraised topics on the Internet. Important information is extracted automatically and regularly from CAT websites, and consolidated by checking the uniqueness and availability. The principle of meta-search is incorporated into the implementation of the search engine, which finds relevant topics following keyword input. The retrieved result directs the physician to the original resource page. A full-text article of a particular topic can be converted into a proper format for downloading to Personal Digital Assistant (PDA) devices. In summary, the application provides physicians with a common interface to retrieve relevant CATs on particular clinical topics from multiple resources, and thus speeds up the decision making process.

Algorithms↗

PubMed2005

High capacity implantable data recorders: system design and experience in canines and Denning black bears.

BACKGROUND: Implantable medical devices have increasingly large capacities for storing patient data as a diagnostic aid and to allow patient monitoring. Although these devices can store a significant amount of data, an increased ability for data storage was required for chronic monitoring in recent physiological studies. METHOD OF APPROACH: Novel high capacity implantable data recorders were designed for use in advanced physiological studies of canines and free-ranging black bears. These hermitically sealed titanium encased recorders were chronically implanted and programmed to record intrabody broadband electrical activity to monitor electrocardiograms and electromyograms, and single-axis acceleration to document relative activities. RESULTS: Changes in cardiac T-wave morphology were characterized in the canines over a 6 month period, providing new physiological data for the design of algorithms and filtering schemes that could be employed to avoid inappropriate implantable defibrillator shocks. Unique characteristics of bear hibernation physiology were successfully identified in the black bears, including: heart rate, respiratory rate, gross body movement, and shiver An unanticipated high rejection rate of these devices occurred in the bears, with five of six being externalized during the overwintering period, including two devices implanted in the peritoneal cavity. CONCLUSIONS: High capacity implantable data recorders were designed and utilized for the collection of long-term physiological data in both laboratory and extreme field environments. The devices described were programmable to accommodate the diverse research protocols. Additionally, we have described substantial differences in the response of two species to a common device. Variations in the foreign body response of different mammals must be identified and taken into consideration when choosing tissue-contacting materials in the application of biomedical technology to physiologic research.

Acceleration↗

PubMed2003

A robust, real-time control scheme for multifunction myoelectric control.

This paper represents an ongoing investigation of dexterous and natural control of upper extremity prostheses using the myoelectric signal (MES). The scheme described within uses pattern recognition to process four channels of MES, with the task of discriminating multiple classes of limb movement. The method does not require segmentation of the MES data, allowing a continuous stream of class decisions to be delivered to a prosthetic device. It is shown in this paper that, by exploiting the processing power inherent in current computing systems, substantial gains in classifier accuracy and response time are possible. Other important characteristics for prosthetic control systems are met as well. Due to the fact that the classifier learns the muscle activation patterns for each desired class for each individual, a natural control actuation results. The continuous decision stream allows complex sequences of manipulation involving multiple joints to be performed without interruption. Finally, minimal storage capacity is required, which is an important factor in embedded control systems.

Action Potentials↗

PubMed2005

Probabilistic finite-state machines--part I.

Probabilistic finite-state machines are used today in a variety of areas in pattern recognition, or in fields to which pattern recognition is linked: computational linguistics, machine learning, time series analysis, circuit testing, computational biology, speech recognition, and machine translation are some of them. In Part I of this paper, we survey these generative objects and study their definitions and properties. In Part II, we will study the relation of probabilistic finite-state automata with other well-known devices that generate strings as hidden Markov models and n-grams and provide theorems, algorithms, and properties that represent a current state of the art of these objects.

Algorithms↗

PubMed2005

Probabilistic finite-state machines--part II.

Probabilistic finite-state machines are used today in a variety of areas in pattern recognition or in fields to which pattern recognition is linked. In Part I of this paper, we surveyed these objects and studied their properties. In this Part II, we study the relations between probabilistic finite-state automata and other well-known devices that generate strings like hidden Markov models and n-grams and provide theorems, algorithms, and properties that represent a current state of the art of these objects.

Algorithms↗

PubMedDate not supplied

A new instrument for continuous recording of the evoked compound electromyogram in the clinical setting.

To study neuromuscular transmission, observation of the evoked compound electromyogram (EMG) has important advantages over observation of the evoked mechanical muscle contraction. Technically, however, recording of the evoked compound EMG, especially in continuous study of several hours duration, has been difficult. Investigators have employed various complicated systems, including tape recording, photorecording, and photographing for such purposes. The authors have applied modern computer technology to construction of an EMG analyzer which enables handling the evoked EMG even more easily than the evoked mechanical contraction. The principle involves digital dissection, storage with memory, readout with time expansion, and analog reconstruction of the compound EMG. The signal can be recorded with ease by use of any suitable hot-stylus or ink-writing oscillographic recorder. Both the waveform and the amplitutde of the EMG can be on-line recorded. The cost compares favorably with comparable devices for similar studies.

Electromyography↗

PubMed1990

[Video technique for documentation of endoscopic findings].

We present a method for recording medical findings using a single chip camera, monitor, storage device and a graphic printer. Statistical and functional findings can quickly be determined and recorded by instant graphics. These screen prints are repeatedly accessible at any time for medical records. This simplifies the diagnostic counselling of the patient as well as aiding the pre-operative discussion amongst the medical team.

Adult↗

PubMed2000

A centralized dose calculation system for radiation therapy.

Centralization of treatment planning in a radiation therapy department is a realistic strategy to achieve an integrated and quality-controlled planning system, especially for institutions with numerous affiliations. The rapid evolution of computer hardware and software technology makes this a distinct possibility. However, the procedure of three-dimensional treatment planning involves a number of steps, such as: (1) input of patient computed tomography (CT) images and contour information; (2) interactions with local devices such as a film digitizer; and (3) output of beam information to be integrated with the record and verify the system. A full-fledged realization of the web-based centralized three-dimensional treatment planning system will require an extensive commercial development effort. We have developed and incorporated a web-based Timer/Monitor Unit (MU) program as a first step towards the full implementation of a centralized treatment planning system. The software application was developed in JAVA language. It uses the internet server and client technology. With one server that can handle multiple threads, it is a simple process to access the application anywhere on the network with an internet browser. Both the essential data needed for the calculation and the results are stored on the server, which centralizes the maintenance of the software and the storage of patient information.

Computer Systems↗

PubMed1999

Seamless multiresolution display of portable wavelet-compressed images.

Image storage, display, and distribution have been difficult problems in radiology for many years. As improvements in technology have changed the nature of the storage and display media, demand for image portability, faster image acquisition, and flexible image distribution is driving the development of responsive systems. Technology, such as the wavelet-based multiresolution seamless image database (MrSID) portable image format (PIF), is enabling image management solutions that address the shifting "point-of-care." The MrSID PIF employs seamless, multiresolution technology, which allows the viewer to determine the size of the image to be viewed, as well as the position of the viewing area within the image dataset. In addition the MrSID PIF allows control of the compression ratio of decompressed images. This capability offers the advantage of very rapid image recall from storage devices and portability for rapid transmission and distribution using the internet or wide-area networks. For example, in teleradiology, the radiologist or other physician desiring to view images at a remote location has full flexibility in being able to choose a quick display of an overview image, a complete display of a full diagnostic quality image, or both without compromising communication bandwidth. The MrSID algorithm will satisfy Joint Photographic Experts Group (JPEG) 2000 standards, thereby being compatible with future versions of the Digital Imaging and Communications in Medicine (DICOM) standard for image data compression.

Algorithms↗

PubMedDate not supplied

Dermatoscopy of "dysplastic nevi": a beacon in diagnostic darkness.

The sequential progression model for melanocytic tumours from common nevus to malignant melanoma was proposed by Clark almost 30 years ago. The "dysplastic nevus" has frequently been considered a logical offspring of this concept and as a direct precursor of melanoma, analogous to the epithelial dysplasia-carcinoma sequence. Despite the use of modern molecular methods, there is no consensus as to if the dysplastic nevus represents a true precursor lesion of melanoma, a separate distinct type of nevus, or a diagnostic dilemma. Currently, the concept of melanocytic dysplasia remains subject to confusing definitions at all levels of the diagnostic process, i.e. clinical appearance, dermatohistopathology, and molecular biology. In this review, we collect evidence that nevi fulfilling Clark and Elder's classic histological criteria mostly represent "endpoints" of nevocytic evolution, whereas a minority of "dysplastic nevi" represent true melanoma precursors. The unsolved dilemma is that neither clinical, histopathological nor molecular criteria exist to make a distinction between dysplastic nevi and early melanomas. Our analysis of the current knowledge on dysplastic nevi shows that dermatoscopy remains the only quantifiable, easily applicable and reproducible diagnostic tool to approach the problem. Due to a "quantum leap" in optical resolution, objective scores can be established, e.g. the total dermatoscopy score (TDS) according to the ABCD rule, and documentation of changes over time are possible by digital image storage devices. Although dermatoscopy does not solve the dilemma of discriminating early, basically feature-less melanomas from dysplastic nevi, and it does not prove that dysplastic nevus is a distinct entity, it helps make melanocytic tumours with unclear malignant potential a manageable disease.

Dermatology↗

PubMed1994

A direct computer control concept for mammalian cell fermentation processes.

In the last 10 years, new assignments and the special demands of mammalian cells to the culture conditions caused the development of complex small scale fermentation setups. The use of continuous fermentation and cell retention devices requires appropriate process control systems. An arrangement for control and data-acquisition of complex laboratory-scale bioreactors is presented. The fundamental idea was the usage of a standard personal computer, which is connected to pumps, valves and sensors via ADA-transformation. The possibility of free programming allowed the development of user-oriented software, especially designed for the far-reaching requirements of a university laboratory in the field of animal cell culture. Control of aeration, pumps, data-acquisition and data-storage are combined within one program, which allows the automation of standard operations like measurement of kLa- or OTR-values. Pump control algorithms for all common fermentation strategies (batch, fed batch, chemostat, perfusion) are included and can be selected any time during cultivation. Oxygen partial pressure and pH are controlled via direct digital control (ddc), providing simple adaption of control parameters and set points to current fermentation conditions.

Animals↗

PubMed2000

Fred Hollows lecture: digital screening for eye disease.

The purpose of this study was to explore progress, in the adaptation to community screening for blinding eye disease, of digital imaging devices and technology for storage and transmission. Available imaging systems were compared to gold standard clinical photography in terms of sensitivity and specificity for diagnosis of common blinding eye conditions. Since the use of expensive non-portable imaging devices is likely to be limited for widespread community screening purposes, a portable fundus camera (Nidek, Chiyoda-ku, Japan) and a prototype monocular digital indirect ophthalmoscope constructed at the Lions Eye Institute (LEI) were selected for comparative trials for the screening of optic disc cupping, glaucoma and clinical signs of diabetic retinopathy. Fifty-one eyes of 27 consecutive patients being assessed at the LEI clinic for glaucoma were dilated and photographed with a Zeiss retinal camera, and digital images were taken with the portable Nidek NM100 fundus camera (Carl Zeiss, Oberkochen, Germany) or with a prototype digital monocular indirect ophthalmoscope. Vertical cup: disc ratios (VCDR) were measured on the disc photographs by one ophthalmologist while three other clinicians were presented with compressed digital images in random order to estimate VCDR. Field trials were also carried out to demonstrate the practicality of compression, local storage and then transmission by mobile telephone ISDN lines and satellite, of optic discs and fundus images of patients with diabetes in either rural Western Australia or Surabaya, Indonesia. Kappa values of correlations of measurement of agreement between measured and estimated VCDR were 0.87, 0.45 and 0.84, respectively, for the three observers, corresponding to a specificity of 79-97% and a sensitivity of 70-95%. The portable Nidek fundus camera was also assessed for specificity and sensitivity in the diagnosis of diabetic retinopathy in comparison to standard Zeiss fundus camera photographs. Of 49 eyes in 25 consecutive patients attending the LEI clinic for assessment of diabetic retinopathy, three ophthalmologists assessed photographs and images in random order. When used for screening diabetic retinopathy, the digital images of the Nidek camera were graded as adequate quality in only 56% of eyes compared to 93% of the photographs. The kappa value of agreement in analysis of diabetic retinopathy was only 0.30. The prototype digital monocular indirect ophthalmoscope compared favourably with the Nidek camera. At 1:5 compression, images of size 36 kB transmitted from Surabaya to Perth took 29 s on the mobile telephone, while uncompressed images took 170 s. Images compressed 1:5 were transmitted in 60 s using the satellite telephone, while the uncompressed images took 240 s. Satellite transmission was more expensive but the lines were more stable than telephone connections from Indonesia. Digital imaging is becoming a powerful tool for ophthalmology in clinical records, teaching and research, and interoffice diagnostic opinions. It also has enormous potential for community screening for blinding eye diseases, such as glaucoma and diabetic retinopathy. Inexpensive portable imaging devices that are easy to use, and on which local health workers might be trained, must be developed and validated in terms of sensitivity and specificity of performance. The technology of image capture, image compression, transmission, data base storage and analysis is rapidly evolving and becoming less expensive.

Diabetic Retinopathy↗

PubMed1997

Band-limited morphometric analysis of the intracardiac signal: implications for antitachycardia devices.

Inappropriate electrical therapy and power efficiency play a major role in algorithm implementation for antitachycardia devices (ATD) that capture, store, and analyze the patient electrogram as an adjunct to rate determination. Morphologically based algorithms have been demonstrated to improve specificity, thereby decreasing occurrences of inappropriate electrical therapy. However, morphologically based algorithms are power demanding. Optimization of power efficiency can be achieved by eliminating unnecessary algorithmic computation, but must not compromise the effectiveness of algorithms, which perform direct analysis on raw signals. Significant reductions can be achieved by reduced sampling rates, which allow for increased overall ATD efficiency via concomitant decreases in computation and data storage. This investigation determined the upper and lower bounds for filter cut-off frequency beyond which detection precision by an established morphometric method for arrhythmia classification, correlation waveform analysis (CWA), was unfavorable. Four measurement statistics were used. In ten patients with inducible VT and VF, all bipolar intraventricular electrograms were classified correctly with a minimum passband of 10-50 Hz using any of the four measurement statistics. There was > or = 80% correct classification using all four measurement statistics with passbands having low frequency cutoffs < or = 15 Hz and high frequency cutoffs > or = 50 Hz. Correct classification of > or = 90% of unipolar electrograms during NSR, VT, and VF occurred using all four measurement statistics with a passband of 1-50 Hz. There was > or = 80% correct classification with passbands 1, 10, 15, or 20-500 Hz and 10-50 Hz. The classification of NSR, VT, and VF was most accurate on an intrapatient basis. Accuracy decreased using an interpatient rhythm classification. Optimum filter settings of 1-50 Hz and 10-50 Hz were determined for unipolar and bipolar electrograms, respectively. Sampling data at 120 Hz was found to be sufficient. Bipolar electrode configuration statistically outperformed unipolar data. In conclusion, morphometric analysis of bipolar and unipolar intraventricular electrograms appears to be achievable using band limited data and reduced sampling rates.

Algorithms↗

PubMed1990

Versatile digital data logger: storage of gastrointestinal motility data.

An inexpensive four-channel data logger for recording gastrointestinal potentials is described. A 512 K bytes memory and a sampling speed of 1.25 Hz per channel is adequate for these potentials and permits recordings for up to 27 hours. The small size and light weight allow the device to be carried in a pocket so that recordings can be made while the subject is freely ambulatory. A separate replay unit allows the data stored in the data logger to be presented to a chart recorder or to an interface card in a PC AT. This interface, a Microsoft C vers 5.0 program and the computer display the data as single frames or scrolled, expanded or condensed on either the time or amplitude axis. From the computer the data can be written to a printer and displayed as a chart or to an ASCII format file which can be used for analysis with statistical packages. Examples of recordings from both man and dog are illustrated and the analogue recorded data are compared with data digitally recorded. It is suggested that the data logger has many applications where long-term slow potential changes must be recorded under specially difficult conditions.

Action Potentials↗

PubMed1993

Implantable cardioverter-defibrillator therapy in the absence of significant symptoms. Rhythm diagnosis and management aided by stored electrogram analysis.

BACKGROUND: This report describes the value of stored ventricular electrogram analysis in the diagnosis and management of patients experiencing minimal or no symptoms before implantable cardioverter-defibrillator (ICD) therapy. METHODS AND RESULTS: The study population included 48 patients who received the Cadence Tiered Therapy Defibrillator System, an investigational third-generation ICD with ventricular electrogram storage capabilities. Criteria for arrhythmia diagnosis were based on analysis of the electrogram rate, RR interval variability, and morphology. Twenty-nine of the 48 patients (60%) experienced at least one episode of antitachycardia pacing or shock (one shock or more in 25 of 29 patients) that was preceded by minimal or no symptoms during a mean follow-up of 15.1 +/- 7.8 months. There were 194 tachycardia episodes registered by the device, including 101 for which ventricular electrograms were stored and available for analysis. Of the 101 stored electrograms, 74 were classified as ventricular tachycardia (VT), 24 as non-VT rhythms (atrial fibrillation, 13; supraventricular tachycardia, six; rate-sensing lead disruption, four; T wave oversensing, one), and only three as indeterminate rhythms. Based on the electrogram analysis, changes in tachycardia detection criteria and/or antiarrhythmic drug regimens were implemented and were associated with a reduction in the number of device responses for non-VT rhythms from 24 during the initial study period to three during 11.0 +/- 7.2 months of additional follow-up. CONCLUSIONS: ICD responses in the absence of symptoms are relatively common in third-generation devices with antitachycardia pacing capabilities. Despite potential limitations such as the effect of bundle branch block on the electrogram morphology during supraventricular tachycardia, the availability of electrogram storage capabilities allowed a presumptive diagnosis of the events precipitating asymptomatic device responses. Device reprogramming based on analysis of stored electrograms was associated with a dramatic reduction in the incidence of ICD responses for non-VT rhythms.

Atrial Fibrillation↗

PubMed2004

The impact of information technology on haemophilia care.

The past decade has seen an explosion in the use of computers, data programs, hand-held electronic devices and the Internet. How these advances impact on haemophilia management both now and in the future are discussed from the perspective of haemophilia registries, Internet-based electronic haemophilia treatment records, and the potential for haemophilia telehealth.

Computer Systems↗

PubMed1993

A sampling and storage system for arbitrary biomedical waveforms.

This paper describes a microcontroller based system which can sample, monitor and store, and generate biomedical waveforms. The frequency of the output waveform is controllable. The inherent advantage of this system is the programming flexibility offered by the microcontroller. Applications include patient monitoring, test signal generator for repair and maintenance of EEG or ECG monitoring equipment, and a laboratory simulation device for student educational use.

Computer Simulation↗

PubMed1987

[Computerized data storage of antibiograms obtained by various methods (automatic reading by 2 different systems or manual processing by the disk method) and retrieval of antibiograms and cytobacteriological data using microcomputers].

This software is composed of different programmes. It works on Apple IIe computers. It enables to capture all the data information concerning bacteriological tests to store them and to edit either personnel reports or global lists made out according to different criteria and to study them under both the statistical or the epidemiological aspects. The results of the antibiotic sensitivity test are notified either by an automatic reader (ABAC or API system) when carried out in a liquid environment or by an original computerized device (compass or enlarger) when manually carried out by the disc method. The informations are directly transmitted to the computer. It's possible to make up a common data file that can be exploited as a whole.

Bacteriological Techniques↗