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Biomedical subjects

D C Jeutter

Publications and source records attributed to D C Jeutter.

9 recordsLinked to original sources
PubMed1987

A multichannel PWM telemetry system for kinematic gait analysis.

A multichannel biotelemetry system using pulse-width modulation-frequency modulation (PWM-FM) is described in detail for laboratory construction. Its application in a kinematic gait-analysis system is demonstrated, employing minimally encumbering electrogoniometry and foot-contact switches. The triaxial electrogoniometers sense rotational joint motion, and four foot-switches under the sole of each foot provide information on placement and temporal contact. Signals from the multiple sensors are amplified, encoded by pulse-width modulation, and transmitted at an FM radio frequency of 107 MHz. Received data are decoded and then sampled by a minicomputer for analysis. Results from a comparative study of kinematic gait in five normal subjects and five children with cerebral palsy demonstrate system effectiveness in providing quantitative data and various intrasubject and intersubject gait differences. Factors reviewed in the analysis include swing and stance times; cadence; hip-joint motion in sagittal, coronal, and transverse planes; and sequence of foot placement.

Analog-Digital Conversion↗
PubMed1985

Determination of cardiac output using ensemble-averaged impedance cardiograms.

Although impedance cardiography provides safe and reliable noninvasive estimates of stroke volume in humans, its usefulness is limited by the necessity for subjects to be apneic and motionless. In an effort to circumvent this restriction we studied the validity of ensemble-averaging of impedance data in exercising normal subjects and in intensive-care patients. The correlation coefficient (r value) between 128 ensemble-averaged and standard hand-digitized determinations of stroke volume index from the same records taken during rest and exercise in six normal male subjects was +0.97 (P less than 0.001). The r value for ensemble-averaged stroke volume indices during free breathing and breath hold in the same subjects was +0.92 (P less than 0.001), suggesting that breath hold did not significantly affect the stroke volume estimation. In 14 freely breathing hospital intensive-care patients the r value between simultaneous thermodilution cardiac output readings and ensemble-averaged impedance determinations was +0.87 (P less than 0.01). The results indicate that ensemble-averaging of transthoracic impedance data provides waveforms from which reliable estimates of cardiac output can be made during normal respiration in healthy human subjects at rest and exercise and in critically ill patients.

Adult↗
PubMed1982

Biomedical telemetry techniques.

The landmarks and important state-of-the-art work in biomedical telemetry are reviewed. The advantages provided by transmission of physiologic data from minimally restrained to completely unencumbered subjects with biomedical telemetry systems is discussed both from the standpoint of the wide variety of physiologic parameters and subjects that can be monitored and in terms of the various proven electronic techniques for implementing this mode of physiologic data transmission and recovery. Monitored parameter capabilities now include biopotentials (ECG, EMG, EEG), temperature, mechanical events (muscle force, limb motion), pH, pressure (ICP, blood pressure), and others. The system developments in biomedical telemetry have had the aims of minimizing size, weight, and volume while extending the operating capabilities of the systems in terms of minimum required power, multiplicity of data channels, and reliable operation in the intended operating environment. These developments have progressed from discrete transistor to integrated microcircuit implementations in systems which can encode the physiologic data as FM, PAM, PWM, or PCM. Biotelemeters can be utilized as external (backpack) or completely implantable devices and today may be found in the research laboratory, the intensive care unit, portable patient care units, and in the freely ranging animal in the field usually employing a radio link. Also discussed are considerations for power sources and power source recharging through the tissues of implanted subjects. There are advantages and disadvantages to using biomedical telemetry, to using implanted or external biotelemeters, and to each of the various encoding techniques. These are considered, and the future of biomedical telemetry is projected.

Animals↗
PubMed1976

The effect of an extraluminal transducer on the reproductive capability of the rabbit.

An extraluminally attached microminiature force transducer, designed for reproductive tract contractility measurements, was investigated in terms of its effects on the physiology of the uterotubal junction in the rabbit. The presence or attachment process of the extraluminal force transducer (EFT) did not affect the rate of pregnancy or the number of embryonic implantation sites whether the attached device was silicone rubber or polyethylene-encased. The uterotubal junction was able to retain the blastocyst for the required time after mating, while an examination of postembryonic mortality revealed a rate of one resorption in some experimental groups. The gestation period was unaffected by the EFT, ranging from 30 to 40 days with a mode of 32, while histologic examinations revealed formation of a thin fibroblastic layer, some increased vascularity, and no abnormal leukocytic accumulation.

Animals↗
PubMed1976

Studies of rabbit ovarian contractility using chronically implanted transducers.

A chronically implanted, highly sensitive force transducer was used to study ovarian contractions in the rabbit. The transducer is implanted into the medulla of the ovary through its long axis. The leads are then drawn through the abdominal wall and directed subcutaneously to the back of the neck. The miniature pin connector is fixed into place beneath the skin to facilitate accessibility for repeated recordings, obviating the necessity for anesthesia or serial laparotomies. Intraovarian transducers were implanted in isolated rabbits. Serial recordings of ovarian contractions were made at weekly intervals for 3 weeks, following which ovulation was induced with 100 IU of human chorionic gonadotropin (HCG). Extended recordings were made from 3 through 13 hours after HCG administration to six animals. Recordings revealed increased ovarian contractile activity beginning just before the anticipated time of ovulation. The observations support those of previous acute experiments and demonstrate a relationship between ovarian contractile activity and the process of follicle rupture.

Animals↗