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Results for “Analog-Digital Conversion”

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PubMedDate not supplied

A comparison of gel-to-gel and skin measurements of electrode impedance.

Utilizing an automated test system, measurements of the 10-Hz impedance were made with electrode pairs joined gel-to-gel and electrode quartets on the skin of the backs of human volunteers. Two skin preparation procedures were examined. As a minimum skin preparation, the electrodes were applied to clean, dry skin from which body hair had been shaved if necessary. As a maximal preparation, the electrodes were applied after mild abrasion of the skin with fine emery cloth. Although the impedances measured for electrodes applied to mildly abraded skin correlated well with measurements made with electrodes of the same brand joined gel-to-gel, virtually no correlation was found if the electrodes were affixed to clean, dry skin.

Adult↗
PubMedDate not supplied

Automated measurement and frequency analysis of the pneumocardiogram.

The flow pneumocardiogram (PnCG), ie, measurement of cardiogenic gas movement in and out of the lung during apnea, was transduced by an in-line, high-gain pneumotachograph. A portion of the differentiated PnCG, the dPn/dt IJ wave, has been shown previously to correlate closely with left ventricular function. A simple analog device was designed and tested to measure the dPn/dt IJ amplitude on a practical beat-to-beat basis. Frequency-power spectral analysis showed the PnCG to be a low frequency phenomenon with the systolic component in the 9-to-10-Hz range. Appropriate band-pass filtering of the PnCG and its applicability as an intraoperative monitoring device are presented.

Analog-Digital Conversion↗
PubMed1978

A method for continuous electrocardiodynamic monitoring.

A new method is presented for the monitoring of cardiac time intervals, e.g. in clinical and industrial work investigation. The methods yields 'on-line' the electrocardiodynamic time profile during rest as well as effort, and has applications in health care, sports and occupational medicine. By means of analog processing of an electrocardiographic signal, ear densitogram and beat-by-beat display of the measured cardiac time intervals as amplitude-modulated pulses, an 'electrocardiodynamic time profile' is obtained. In order to estimate the accuracy and the limitations of the method, a comparison with computerized methods was performed. In an ergonomic experiment carried out by a Romanian-Swedish research team, analog and digital methods for the detection of cardiac time intervals showed good agreement.

Adolescent↗
PubMed1979

Apperceptive signals demonstrating the dynamic disturbance of myocardial ischemia.

Analog pressure signals (catheter-tip manometers) from the left atrium, left ventricle, and aorta and a flow signal from the arota were obtained in 25, open-chest, anesthetized dogs in which 115 episodes of ischemia were produced in an area of the left ventricle subtended by the distal left anterior descending coronary artery and its last major diagonal branch. The left ventricular pressure and its first derivative (dP/dt) were displayed as an X-Y loop. The character of this loop went through a unique series of dynamic changes in 110 of the 115 ischemic episodes, indicating that this is a useful tool for monitoring myocardial ischemia. Spectrum pairs of the above signals were analyzed with digital computational transfer functions in 14 ischemic episodes of three experiments and preliminary assessment reveals unique pole and zero changes in many pairs during each episode which also may prove to be a useful indicator of the hemodynamic disturbance incurred during myocardial ischemia.

Analog-Digital Conversion↗
PubMed1976

International standard (C.C.I.T.T.) for transmitting biomedical analogue and digital data on the public telephone network.

Analogue transmission of biomedical signals over the public telephone network has advantages from the economic point of view over digitalized transmission. This paper deals with the special problems encountered with the transmission of biomedical signals. Furthermore, the new international transmission standard C.C.I.T.T. recommendation V. 16 is introduced. This standard has recently been adopted by the relevant study group and has been presented to the Plenary Assembly of the C.C.I.T.T. for final approval. This standard is compatible with the existing public telephone networks. The technical specifications of this standard allow the transmission of the three-channel ECG for diagnostic purposes, e.g., remote processing and computer-assisted evaluation, as well as the transmission of the one-channel ECG with acoustic coupling, e.g., in emergency cases and for pace maker monitoring.

Analog-Digital Conversion↗
PubMed1975

[A hybrid system for documentation of pathological findings (author's transl)].

Considerations on the theory of communication point to the importance of "redundant" data in medicine. These usually arise from texts such as catamneses, descriptions of findings etc., and escape digital data pooling and storage on organizational and financial grounds. Here, microfilm is available as an economical storage medium taking little room. Developments in recent years enable integration of automatic analog storage into digital information systems. The use of such a hybrid system in the field of pathology is described.

Analog-Digital Conversion↗