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At least 181 records · Page 10Linked to original sources
PubMed1988

Development of a telemetry system for measuring oxygen uptake during sports activities.

A new system for continuous measurement of oxygen uptake by means of a telemeter has been developed. Oxygen uptake and pulmonary ventilation during rest and exercise were determined using a portable oxygen consumption meter (Oxylog). A small interface circuit between the Oxylog and the transmitter of a frequency modulated bio-telemeter system was designed and installed inside the Oxylog. Data from the transmitter were passed to a receiver and were fed into a microcomputer system. The microcomputer system displayed and printed out minute values of ventilation and oxygen uptake. The accuracy and reliability of the new system were checked by comparison with the traditional (Douglas bag) method. In the range less than 80 l.min-1 of ventilation and less than 2 l.min-1 of oxygen uptake, the system was not inferior to the Douglas bag method. The new system was applied for field continuous measurement of oxygen uptake during a doubles tennis game. The results of the application indicate that the telemetry system developed here is a very practical and useful way of measuring oxygen uptake during sports activities.

Adult↗
PubMed1981

Telemetry of several biological signals from behaving animals.

A telemetry device is described for recording ECG, EMG, EEG, multiple and single unit activity from central nervous system. It implies the use of a FET input operational amplifier and an FM oscillator. It can be used with different electrodes and in many animal species when behavioral studies and completely unrestrained subjects are requested.

Animals↗
PubMed1993

Changes in cardiac rhythm in man during underwater submersion and swimming studied by ECG telemetry.

A previously reported method for electrocardiographic (ECG) telemetry in water using frequency-modulated current was improved to obtain more stable ECGs. The ECGs of seven healthy men were monitored using the improved method during and after whole-body submersion or underwater swimming. Bradycardia and arrhythmias were observed during the submersion, and transient tachycardia was detected after the start of underwater swimming, followed by bradycardia with arrhythmias. Three different types of arrhythmias were observed: sinus arrhythmia (SA), supraventricular extrasystole (SE) and ventricular extrasystole (VE). SA and SE tended to develop during the latter half of the period of submersion or underwater swimming, and especially after the restart of breathing. VEs were detected in only one subject during submersion, whereas they occurred in most subjects during and after underwater swimming. Individual variations were found in development of arrhythmias, one subject showing no arrhythmia. Bradycardia, SA and SE could depend on vagal suppression in underwater conditions, and VE may be related to the effect of muscular movement on cardiac function in addition to vagal inhibition.

Adult↗
PubMed2005

[ICD: to replace or not to replace, this is the question. the ICD-downgrade + telemetry-upgrade-trial].

Implantable defibrillators (ICDs) have to be replaced after 4-6 years due to battery depletion. Therefore, 195-267 ICDs may be necessary for 100 ICD patients, if device longevity is 6 and 4 years, respectively. In Germany, 35% of all ICDs were replacements in 2003. The percentage of replacements will probably increase to > 50% in the next years. With fixed budgets, a de novo implantation may therefore compete with an exchange ICD in the future. The explantation of an ICD is currently only possible under special circumstances, even in patients without adequate therapies during recent years, since data on the risk of a sudden cardiac death after an explantation are rare and contradictory. However, a downgrading of the ICD in patients without any therapies in recent years may be feasible, i. e., the ICD may be programmed to a shock-only device with a therapy delay of 15 s. This may even result in an increased longevity of the devices. This concept will be prospectively tested in the randomized ICD-Downgrade + Telemetry-Upgrade study.

Defibrillators, Implantable↗
PubMed2005

Using stable isotope analysis with telemetry or mark-recapture data to identify fish movement and foraging.

Information about animal movements has often been inferred from stable isotope analysis (SIA), but is dependent on animals assimilating site-specific isotopic signatures via diet. This potential weakness in ecological interpretation can be overcome by using other investigative tools that provide precise information about individual movement patterns. In this paper, we demonstrate the value of combining SIA with telemetry or mark-recapture data from trapping, electrofishing and remote detection of individuals to study the movement and feeding ecology of fishes in different habitats. In a fjord lake system in Newfoundland, Canada, juvenile Atlantic salmon delayed downstream migration (smolts) or actively moved into a large lake (parr) where they foraged for periods reflecting different life history strategies. In the Miramichi River (New Brunswick, Canada), SIA provided evidence of distinct foraging habitats (tributary versus large river). By tracking fish implanted with passive integrated transponder (PIT) tags, we distinguished between movements related to foraging versus seeking cool water refugia during high temperature events. Finally, site fidelity and limited mobility of slimy sculpin, a small benthic fish, was established where delta13C in muscle tissue showed a progressive enrichment downstream and where a median displacement of <10 m was estimated for sculpin tagged with PIT tags. Technological improvements have permitted non-destructive tissue sampling of wild fishes for SIA, and the tagging and remote detection of animals smaller than was previously possible. These advancements and the combination of investigative tools promise new insights into animal ecology.

Animals↗
PubMed1984

Telemetry of electrophysiologic variables from conscious dogs: system design, validation, and serial studies.

The necessity for conscious animal models in the study of cardiac physiology has been established for hemodynamics. The characterization of the electrophysiologic properties of the heart has not been performed in a serial fashion in a conscious animal model. Implanted telemetry sensing devices for recording atrial, ventricular, and His electrograms and stimulation systems for both atrium and ventricle allowed serial evaluation of eight dogs for up to 4 months. There were significant fluctuations in some electrophysiologic variables with time, particularly heart rate, sinus node recovery time, and pacing rate for induction of Wenckebach block. This variability did not appear to deviate with time after implantation, and no significant differences in the basal electrophysiologic state were found between the period early after surgery (0 to 2 1/2 weeks) and later (3 to 8 weeks).

Animals↗
PubMed1991

128-channel cable-telemetry EEG recording system for long-term invasive monitoring.

A 128-channel cable-telemetry EEG monitoring system has been developed for use on patients undergoing intensive neurodiagnostic monitoring with invasive intracranial electrodes. A unique head mounted preamplifier/multiplexor design allows continuous recording from any combination of intracerebral, subdural, epidural or surface electrodes. A computer is used to delay or buffer all 128 channels by 2 min or more. This computer is connected to a fileserver via a local area network and is used exclusively for data acquisition. Seizure files created by the activation of the seizure/event push button or detected by a second computer containing on-line seizure/spike detection algorithms are written directly on to the fileserver by the acquisition computer. The 128 channels of EEG recorded on the fileserver can then be remotely reviewed on a high resolution graphics terminal, printed out on a laser jet printer, archived or played out on paper, 16 channels at a time on any EEG machine. A time of day signal is also generated by the computer to permit time correlation with a continuous audio/video VCR unit which permits comparison of the EEG and clinical events. This system allows continuous EEG monitoring of extensive multichannel arrays not previously possible with conventional 16-, 32- or even 64-channel systems.

Electroencephalography↗
PubMed1994

Prevalence of bilateral partial seizure foci and implications for electroencephalographic telemetry monitoring and epilepsy surgery.

Most patients with partial seizures of temporolimbic onset have predominantly unilateral seizure foci, which partly accounts for the success of unilateral temporal lobectomy. The prevalence of bilateral foci is not known. "Discordant" seizures are those which arise from the contralateral side from the usual focus. "Concordance" is the fraction of seizures which arise from the majority side, ranging from 0.5 to 1.0. From observations of seizures recorded in an epilepsy monitoring unit, a model of the patient population can be determined by non-linear least squares methods. Six hundred and five seizures from 57 consecutive patients with non-lesional temporolimbic epilepsy were studied. In the model population, 15% of patients have concordance of less than 70%, and 80% have concordance > 90%. Using Bayes' theorem, the observation of 5 concordant seizures implies a 95% chance of the patient having a concordance of at least 90%. If one discordant seizure is recorded, then to reach the 95% confidence level of 90% concordance requires a total of 11 concordant seizures. For the smaller group of patients with strictly unilateral interictal spikes, only 4 concordant seizures need to be recorded to achieve the same level of confidence of unilaterality. Interpretation of telemetry studies requires knowledge of the patient population.

Brain↗
PubMed1991

Four-channel telemetry system for in vivo measurement of hip joint forces.

The long-term loosening of artificial hip joints remains a serious clinical problem. Optimization of implant design and material will improve the fixation, but it requires a detailed knowledge of the forces which act on the implant. A four-channel telemetric transmitter was developed and arranged completely inside a hermetically closed artificial hip joint. This permits long term in vivo measurements of the three-dimensional forces without endangering the patient. The external telemetry system consists of an inductive power supply, an RF receiver, a microcomputer with hardware extension and a VHS video system. The personal computer offers real-time data processing of three orthogonal force components as well as slow motion analysis of recorded measurements. After several years of animal tests, two instrumented prostheses were implanted in the first patient (male) in May and August of 1988. In March 1990 a third prosthesis was implanted in a second patient (female). Joint force measurements have regularly been performed from the first post-operative day until now for several kinds of activity.

Biomechanical Phenomena↗
PubMed1993

Seven-channel digital telemetry system for monitoring and direct computer capturing of biological data.

A seven-channel telemetry system for collection and display of biological data is presented. The system can amplify bioelectrical signals in the range of 2 microV to 200 mV and has a bandwidth of 0.1-80 Hz. After multiplexing, the signals are digitized with a resolution of 8 bits. The data are frequency modulated directly on a VHF transmitter. After receiving the data on a VHF receiver, they are routed directly to the RS232 input connector on the PC. Thereby the advantage of direct communication between the transmitter and the PC can be utilized. Expensive analog equipment is avoided and display of the signals on the PC screen as well as signal analysis can be performed. The system has been tested and was found to be stable and highly reliable.

Amplifiers, Electronic↗
PubMedDate not supplied

A telemetry study on the chronic effects of microdialysis probe implantation on the activity pattern and temperature rhythm of the rat.

The present study describes the effects of implantation of microdialysis probes on temperature and activity rhythms of the rat, measured with a telemetry system. For comparison two widely used types of microdialysis probes were investigated, a transcerebral probe, inserted into the pineal gland and a set of two I-shaped concentric probes, implanted bilateral into the striatum. Starting from 5 days before the operation until 8 days after surgery, activity and temperature recordings were carried out continuously with the help of previously implanted transmitters. In separate experiments the effects of two different types of anaesthesia (chloralhydrate and Hypnorm) were determined. The results show that there is a pronounced effect of surgery on amplitude and rhythmicity of the temperature and activity patterns which is still detectable 6-7 days after operation. Few differences were noticed between the transverse probe and the I-shaped probes. Anaesthesia alone induced much smaller changes, most of which had disappeared within 2 or 3 days after the treatment. The duration of action of chloralhydrate is somewhat longer compared to Hypnorm. The conclusion is that when microdialysis is used in behavioural experiments, the effects of the surgical procedure should be taken into account. If these effects are serious, the use of previously implanted guide cannulae might be necessary.

Animals↗
PubMed1993

Power spectrum analysis of cardiovascular variability monitored by telemetry in conscious unrestrained rats.

Beat-to-beat variability of arterial pressure and heart period (R-R) was studied in eight conscious freely-moving adult male rats in which telemetric recordings of arterial pressure, ECG and respiratory movements were obtained under unrestrained and unstressed conditions. The beat-to-beat time series of these signals (systolic arterial pressure, diastolic arterial pressure and R-R) were analyzed, in the frequency domain, using autoregressive spectral analysis in order to detect and quantify the rhythmic components. In basal conditions, the systolic arterial pressure variability spectrum was characterized by three major spectral components which had central frequencies respectively of 0.08 +/- 0.03 Hz (very low frequency), 0.43 +/- 0.02 Hz (low frequency) and 1.36 +/- 0.19 Hz (high frequency). Similar rhythmic components were found in R-R signal variability. The very low frequency component included a higher percentage of total power in R-R variability spectrum (75.3%) than in systolic arterial pressure variability spectrum (58.4%). The low frequency component was more pronounced in both systolic and diastolic arterial pressure variability spectra. The high frequency component of R-R, systolic and diastolic arterial pressure was synchronous with respiration. Cross-spectral analysis revealed a high statistical coherence between R-R and arterial pressure variabilities in all the three frequency bands. An alpha-adrenergic blocker (phentolamine) specifically abolished the low frequency components of systolic and diastolic arterial pressure variability spectra, thus suggesting that low frequency is a marker of sympathetic modulation of vasomotor activity. The low frequency component of R-R variability spectrum was also markedly blunted. We suggest that cardiovascular variability signals, (R-R, systolic and diastolic arterial pressure) are composed almost of two main rhythms linked to respiration and vasomotor activity. These rhythms can be quantified in conscious unrestrained rats by using telemetry and spectral analysis. This approach seems to offer a new powerful tool for pharmacological studies in conscious small animals.

Animals↗
PubMed1995

Circadian and short-term variabilities in blood pressure and heart rate measured by telemetry in rabbits and rats.

Blood pressure (BP) and heart rate (HR) were measured by telemetry in conscious unrestrained rabbits to clarify the profile of their variabilities. The variabilities were assessed for two periods, 24 h (circadian rhythm) and 1 h (short-term variability), and compared with those in rats. BP and HR in rabbits were lower than those in rats but the circadian rhythms in rabbits showed nocturnal patterns as is the case in rats. In contrast, short-term variabilities in BP in rabbits were considerably larger than those in rats. The short-term variability in BP in rabbits was suppressed by alpha-adrenergic blocking without changes in basal values but not by beta-adrenergic blocking or angiotensin converting enzyme inhibition. These results demonstrate the need to take the unique characteristics of short-term variability in BP in rabbit into consideration when the circadian rhythm is focused on and that the short-term variability in BP in rabbits is caused mainly by activation of alpha-adrenergic receptors.

Animals↗
PubMed1994

Diver monitoring by ultrasonic digital data telemetry.

A through-water ultrasonic data telemetry system using burst-mode frequency shift keying (FSK) is described. The system can be adapted for the transmission of data from various sensors, but it has been designed principally for monitoring the respiratory rate, heart rate, temperature and depth of a free-swimming diver over a range of up to 300 metres. This application requires the transmission of low rate digital signals through water from a moving source to a receiver that is either stationary or moving.

Amplifiers, Electronic↗
PubMed1995

Fading characteristics of a 2.3 GHz radio telemetry channel in a hospital building.

This paper reports on radio path attenuation measurements made in a hospital complex at a spot frequency of 2.340 GHz. Power loss figures for fixed path propagation in a variety of building types have been determined for proposed telemetry use in operational ward situations. Throughout the hospital, the radio paths assessed all exhibited a loss in excess of that calculated for free-space communications. Modern buildings had external wall losses of 10-25 dB, with dividing walls in wards contributing an additional 5 dB. Received signal strength levels indicated a Rayleigh distribution for obstructed paths. Temporal testing was used to find the rate and depth of signal fades caused by the movement of personnel and equipment during normal ward usage; signal level reductions of greater than 35 dB were common during busy periods.

Biomedical Engineering↗
PubMed2005

First experience with a Mobile Cardiac Outpatient Telemetry (MCOT) system for the diagnosis and management of cardiac arrhythmia.

Recently, a mobile cardiac outpatient telemetry (MCOT) system has become available that monitors the electrocardiogram continuously, recognizes arrhythmias automatically, and transmits abnormal rhythms instantaneously. MCOT does not require activation by the patient. We report data from the first 100 consecutive patients monitored by this new technology.

Adolescent↗
PubMed2004

Behavioural and cardiovascular responses during latent inhibition of conditioned fear: measurement by telemetry and conditioned freezing.

This study assessed freezing behaviour and cardiovascular responses during the expression of latent inhibition of conditioned fear. Animals that were either repeatedly preexposed (PE) to a tone conditioned stimulus (CS) or naive to the tone (non-preexposed; NPE) subsequently experienced three presentations of the tone paired with footshock. Animals were tested 24 h later in the context of the footshock chamber, and on the following day, in the presence of the tone CS. Changes in heart rate and blood pressure were recorded by radio-telemetry. The PE rats spent more time freezing to the conditioned contextual cues and exhibited higher blood pressures during the last half of the context test session than did the NPE animals. During the tone test, the PE rats exhibited less conditioned freezing to the tone CS compared with the NPE animals, i.e. expression of the latent inhibition. This behavioural effect was associated with a significant increase in heart rate, but not blood pressure, in the PE but not the NPE animals. Our results suggest that the increased blood pressures of the PE rats during the context test directly reflect their greater fear of the conditioning context. In contrast, the increased heart rate response but decreased freezing shown by PE rats in response to the tone CS may be due to the fact that lower stress levels (e.g. PE condition) elicit sympathetically-mediated increases in heart rate, whereas higher stress levels (e.g. NPE condition) activate both sympathetic and parasympathetic systems, thus eliminating any CS-induced increase in heart rate in the NPE rats.

Animals↗