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This thesis is about a new technology of program-controlled telemetry for pacemakers. The system utilizes digital logic circuit design, and the program-controlled part uses single chip to control for display and debug. PWM and reflectance telemetry may improve the preciseness and correctness of signal transmission, and reduce the power consumption of pacemakers and prolong the lifetime.
The diagnosis of epilepsy is sometimes difficult in childhood. The events witnessed in children may be atypical and the interictal electroencephalogram (EEG) may be normal or contain non-specific abnormalities. The problems may be overcome by recording events on video-EEG telemetry. Over the first 18 months of this service, 82 patients were monitored--42 males and 40 females. Forty-two were daytime studies, 37 day and night, and 3 night only. Surface electrodes only were used. The system used was the 24-channel la Mont Video-telemetry unit from Medical Systems International. Parents served as observers. Events and a sample of interictal data were analysed. The commonest reason for referral was to determine whether an event was ictal. Other reasons included seizure frequency, classification or localization of onset. Presenting events were unusual motor activity, staring, change of behaviour, distressing visceral sensations, combinations of the above and miscellaneous phenomena. Events occurred during the recording in 66 of 82 subjects. Of these, 23 were judged to be ictal. These were complex partial seizures, absence seizures, myoclonic jerks, generalized tonic seizures, gelastic seizures and mixed seizure disorders. The non-ictal events were commonly habit tics or normal sleep phenomena, although pertussis, pallid syncopal attacks and extrapyramidal movements occurred. In 76% of cases the management of the child's condition was influenced by the telemetric study.
An inexpensive but reliable telemetry system for long-term, sequential monitoring of body temperature in up to 20 laboratory animals is described. The system consists of frequency-modulated (FM) temperature transmitters, remote-controlled power switches to extend battery life, a multi-channel telemetry receiver, and a frequency counter interfaced with a personal computer to record data. Analysis of body temperature data obtained from four New Zealand White rabbits confirms the reliability and value of this system.
A new pH capsule telemetry technique was used to measure the pH fluxes in the upper part of the gastrointestinal tract in normal volunteers, symptomatic patients and in those with hiatal herniorrhaphy during the preoperative and postoperative period. The Darvon-sized pH capsule is swallowed with ease and with minimal discomfort by a fasting patient. The pH of the surrounding media activates an FM radio transmitter within the capsule to emit a continuous radio signal which is converted by a receiver to a linear graph on a strip chart recorder. This pH capsule telemetry test is easy to perform on an ambulatory basis and allows an accurate and reproducible determination of the presence or absence of esophageal reflux in patients with and without a hiatal hernia. Its correlation with symptomatic reflux is higher than that found with a conventional gastrointestinal series examination. The technique allows a much clearer distinction to be made between those patients with real symptomatic esophagitis secondary to actual reflux and those with other esophageal, cardiac or pulmonary symptoms existing withour reflux. This study also reveals a consistently lower fasting gastric pH in patients with signs and symptoms of reflux than in normal individuals without reflux. The technique enabled a more accurate assessment of the efficacy of hiatal hernia repair and revealed a reduced degree of esophageal reflux in those patients who had undergone successful repair with fundic plication.
A new passive telemeter for the intracranial pressure monitoring have been developed. The completely implantable pressure sensor used in this system consists of a crystal, a coil and a ferrite rod attached on a diaphragm. The pressure on the diaphragm alters the volume of air in the receptacle and then the ferrite rod moves in and out of the coil and alters the resonance frequency of the sensor. Although the sensor doesn't have a battery or other energy storer, for example, a capacitor, the resonance frequency can be measured without contact. Therefore, at any time, we can measure the intracranial pressure with this sensor implanted under the scalp beforehand. However, not only pressure but also temperature alters the resonance frequency of the sensor, because the volume of air alters in proportion to temperature. Hence, we have developed a new passive telemetry pressure sensor which contains a passive telemetry temperature sensor. The temperature sensor consists of a coil and a special crystal whose resonance frequency varies with ambient temperature and its resonance frequency can be measured in the same way that we measure the resonance frequency of pressure sensor from outside of the body. With this system, we can measure the intracranial pressure about 60 times per second and the intracranial temperature every 8 seconds. The measured value of the pressure was automatically corrected by analog temperature correcting electric circuits. In animal experiment, the output of this system was similar to one of the catheter-tip type pressure transducer and we could observe the intracranial pressure altered synchronizing with respiration and with heart beat.
The fetal electrocardiogram (ECG) in 23 ambulatory women in labor was monitored successfully with a single-channel FM telemetry unit with a 0.5-100-Hz wideband receiver to improve the quality of the ECG complex. An inverted QRS complex was seen in a patient with a deceleration and an inverted T wave during a deceleration in a patient confined to bed. A maternal artifact was transmitted in a third. The ECG complex was identical when wired patients were switched to telemetry. Thus, fetal heart rate and ECG configuration can be monitored accurately in ambulatory pregnant women.
A radiotelemetry system for the direct monitoring of fetal heart rate and intrauterine pressure during labor has been evaluated at 5 different institutions. A conventional fetal scalp electrode and a special intrauterine pressure sensor are connected to a radio transmitter placed on the patient's thigh. The receiver can be located up to 50 feet away from the transmitter and is either a self-contained monitor or a unit that converts a conventional fetal monitor to a telemetric one. The telemetry recordings are of similar quality to those obtained from conventional monitors. Telemetry allows for greater patient comfort and mobility as well as greater convenience to the clinical staff. Continuous data can be obtained from patients while they are ambulatory or sitting in a chair as well as while they are in bed.
Data transmitters and power/source controllers are common elements in all totally implantable instrumentation systems. Two custom-designed integrated circuits have been developed for these elements and have significant impact on the realization of compact reliable telemetry packages. The first is an elapsed-time power switch that can remotely turn on implanted battery-powered systems with a short RF burst; to prevent accidental battery drainage, it will automatically turn off after a preprogrammed time (1-5 min). The second is a precision RF transmitter capable of operation up to 125 MHz in either FM or pulse-coded format and requires only two nonintegrated inductors. These IC systems are basic building blocks for a large number of totally implantable telemetry applications.
The motivation for the development of advanced totally implantable telemetry systems is to improve the quality of medical care through a more detailed understanding of basic physiological processes. Three research protocols in electrophysiology, hepatic hemodynamics, and cardiac pharmacology are described which rely on new implantable instrumentation; these devices allow chronic measurements in the conscious animal of such diverse parameters as aortic and ventricular pressures; atrial, ventricular, and bundle of HIS electrograms; aortic and coronary blood flow, and total hepatic blood flow by measuring velocity profiles in the portal vein and the hepatic artery. The compact size and high reliability now achievable with these telemetry systems provides new tools to the researcher for the study of the body in health and disease.
A long-range and long-life telemetry system for heart rate and multiple body temperatures from free-ranging animals is described. This system includes an implantable transmitter, external receiver-retransmitter collar, and a signal conditioner interface circuit to assist in demodulation of receiver tone outputs before data processing. The size of the implant is suitable for animals with body weights of a few kilograms or more; further size reduction of the implant is possible. The ECG is sensed by electrodes designed for internal telemetry and to reduce movement artifacts. The R-wave characteristics are then specifically selected to trigger a short radio frequency pulse. Temperatures are sensed at desired locations by thermistors and then, based on a heart-beat counter, transmitted intermittently via pulse interval modulation. This modulation scheme includes first and last calibration intervals for a reference by ratios with the temperature intervals for as much as a range of 0-50 degrees C with a resolution of 0.1 degrees C. Pulse duration and pulse sequencing are used to discriminate between heart rate and temperature pulses as well as radio frequency interference. The implanted transmitter might be used alone for experiments on animals that frequent particular locations within a large territory, on animals in virtually any laboratory situation, or on animals in moderate-sized enclosures, such as those in a zoological garden. The implanted transmitter is otherwise interfaced with the receiver-retransmitter collar that employs commercial tracking equipment to achieve the long-range transmission. The objective of the design was to achieve a high degree of experimental flexibility and overall high quality in performance. The system was tested in prototype form on a dog.
To use staff more effectively on a medical telemetry unit, nurses collaborated with clinical engineers to incorporate a commercially available pocket pager with a dysrhythmia detection system. Nurses carry a pocket pager which beeps and displays the patient's room number when a dysrhythmia is detected. This system eliminates the need for a telemetry monitor watcher and provides nurses with ongoing information about their patients. It also created an annual savings of approximately $130,000.
A commercially available adult telemetry unit was adapted for use in fetal heart rate monitoring. Advantages included permitting the mother to ambulate during labor, monitoring the fetus while the mother was in transit from the labor to the delivery area and reducing electrical noise levels. Patient as well as physician acceptance has been uniformly excellent. Patients who normally would not have accepted monitoring acceded to the use of the telemetry system when informed that they could move about while in labor. The equipment is easy to adapt, widely available, relatively inexpensive and simple to use.
We investigated the effect of an acute stressor on body temperature and heart rate in cows. Both parameters were recorded by active telemetry. For the experiments, five cyclic Brown Swiss cows were used, each of them exposed to an acute stressor during estrus and the luteal phase of the cycle. The stressor consisted in restraining the cows in a crush for hoof treatments. During the 2-hour stress period and for additional 6 hours, body temperature and heart rate were measured every 10 minutes. Control animals remained in their accustomed environment during the whole experiment of 8 hours. The course of body temperature and heart rate was clearly influenced by the stressor. While heart rate was maximal already at the beginning of the stress period, the body temperature showed highest values only one hour after stress and then continuously decreased. Changes in body temperature and heart rate under stress differed significantly from the values of control animals. Both parameters are reliable indicators of stress in the bovine species. The transmitters used in this investigation allowed us to register exact data without manipulation of the animal, which could possibly falsify the results. This advantage as well as the functional longevity of the transmitters (ca. 6 months) make active telemetry a useful tool for stress research in farm animals.
Remote thermal telemetry was performed on North American river otters (Lutra canadensis) during the 1995 North Carolina Wildlife Resources Commission Otter Restoration Project. Otters were anesthetized with either ketamine-midazolam (n = 11) or tiletamine-zolazepam (n = 9) combinations. Based upon initial rectal temperatures, mild to moderate hyperthermia (39.4-40.5 degrees C) developed in five otters given ketamine-midazolam and three otters given tiletamine-zolazepam. Following anesthetic induction, each otter received an ingestible temperature transmitter. Dependent upon gastrointestinal transit time and transmitter battery life, core body temperature was monitored for up to 13.75 hr postanesthesia. Thermal telemetry revealed a gradual decline in core temperature in all otters after anesthetic recovery (30-60 min). Median core temperature stabilized subsequently within 0.3 degrees C of resting temperature (38.4 degrees C) 1.75 hr after initial injection in otters given tiletamine-zolazepam and 2.75 hr in otters given ketamine-midazolam. Minor fluctuations in body temperature (less than 1 degree C) occurred in most otters from 6 to 13.75 hr and were attributed to variations in physical activity.
OBJECTIVE: This study aimed to compare recordings of the electrically evoked whole nerve action potential (EAP) made using the reverse telemetry system of the Nucleus CI24M device with those recorded from individuals who use the Ineraid cochlear implant system. STUDY DESIGN: Data were collected in a prospective fashion from Nucleus CI24M cochlear implant users and compared with retrospective data collected from patients who use the Ineraid device. SETTING: All data were collected at the Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics. PATIENTS: Data are reported from 8 patients who use the Nucleus CI24M cochlear implant and 20 patients who use the Ineraid cochlear implant system. INTERVENTIONS: The interventions described in this study were diagnostic in nature. MAIN OUTCOME MEASURES: EAP growth and refractory recovery data are reported. EAP thresholds recorded from patients who use the Nucleus CI24M device also are compared with behavioral thresholds for the stimulus used to evoke the EAP as well as the stimulation levels needed to program the speech processor. RESULTS: EAP morphology, growth, and refractory recovery functions recorded using the Nucleus CI24M reverse telemetry system compared favorably with similar measures recorded from Ineraid cochlear implant users. CONCLUSIONS: Reasonable EAP responses can be recorded using the Nucleus CI24M device. More data are needed to determine whether the information about neural responsiveness available with this device will be clinically useful.
Space missions currently on the drawing boards are expected to gather data at rates exceeding the transmission capabilities of today's telemetry systems by many orders of magnitude. Even on current missions, onboard data compression techniques are being implemented to compensate for lack of transmission speed. But while data compression can minimize the loss of data, it is no substitute for transmitting all of the data through a faster communications link. The transmission problem will soon reach crisis proportions and will affect astronomical, Earth resources, geophysical, meteorological, planetary and other space science missions. To overcome this communications bottleneck, the authors advocate the implementation of telemetry systems based on near-infrared laser transmission techniques. The fiber-optics communications industry has developed most of the basic components required for signal transmission in this wavelength band, which should make such a system affordable on scales relevant to the cost of anticipated space science missions.
This action changes rules in the Special Emergency Radio Service to permit the limited use of bio-medical telemetry systems on certain medical services VHF frequencies. The operation is to be allowed only beyond fifty miles from the center of urbanized areas of 600,000 or more population (U.S. Census of 1970). The bio-medical telemetry system is used to send electrocardiograms from patients to hospitals.
Desethylamiodarone (DEA), the major active metabolite of amiodarone (AMD), plays a significant role in the electrophysiological effects observed during AMD therapy. The pharmacokinetics and pharmacodynamics of DEA were studied in rats. Animals were administered DEA (20 or 40 mg kg-1) and blood samples were collected. The heart rate, PQ, QR, QS, QT, RR intervals, and P,R,S, and T amplitudes were also measured after dosing using telemetry. DEA followed a biexponential decline with a t1/2beta of 54 center dot 8 and 46 center dot 2 h after the 20 and 40 mg kg-1 doses, respectively. The relationship between DEA and the QT interval or T amplitude was best described by a sigmoid Emax model. The mean (+/- SD) Emax for QT and T amplitude was 32 center dot 23 (+/- 2 center dot 47)% and 0 center dot 12(+/- 00 center dot 9) mV, respectively. The mean (+/- SD) EC50 value was 297 center dot 5 (+/- 22 center dot 80) ng ml-1 for QT and 139 center dot 8 (+/- 28 center dot 69) ng mL-1 for the T amplitude. The electrophysiological changes observed with DEA are similar to those with AMD. These results further support the contribution of DEA to the efficacy noted during AMD therapy and provide and viable animal for continued description of this relationship.