Biotelemetry System Research Articles

Twenty-four-hour pattern of ventricular excitation rhythm in resting normal human subjects.

Using a biotelemetry system, the electrocardiogram (ECG) was continuously measured over 24 hr in a given environmental condition in 8 normal human subjects. The frequency of ventricular excitation rhythm (VER) was obtained from inverse of R-R interval of ECG. This study was undertaken to be informed of the variation of VER over 24 hr in resting normal subjects with different ages. The averaged frequency of VER per day (VERd) and its relative coefficient of variation (CV) ranged from 1.44 to 1.01 Hz (mean: 1.24 Hz) and 26 to 10% (mean: 20%) with age of 10 to 73 years (mean: 42 years). VERd and CV showed a tendency to decrease with age. The VERd histogram showed not a normal distribution but a multimodal distribution. Two or three large positive deviations, denoted as L, N, and H modal components, from the normal distribution curve were detected. The mode of L and H modal components was 1.01 and 1.37 Hz, respectively. The frequency distribution of L and H modal components changed with relation to a circadian rhythm and sleep-wakefulness cycles. An hourly histogram of ventricular excitation rhythm (VERh) frequently showed an unimodal distribution and the relative coefficient of variation of VERh ranged from 7.9 to 13.3% which was smaller than that of CV. The mode of VERh histogram changed in association with the circadian rhythm, the sleep-wakefulness cycles and a fluctuation period of 2 to 3 hr.

Hybrid Circuit for Stimulated Bone Regrowth

A hybrid circuit using a custom-designed I2L IC for a four-channel implantable biotelemetry system together with a HF transmitter has been designed. It realises a high-performance and economical device.

Circadian rhythms in monkeys: Variability and behavioral correlations

Heart rate (HR) and body temperature (BT) data were collected for a total of eighty 24-hour days from 5 infant pigtailed ( M. nemestrina) monkeys using totally implantable multichannel biotelemetry systems. Best fit (least squares) cosine functions were fit to each 24-hour block of HR and BT data providing estimates of circadian cosine level, amplitude and phase. Within animal correlations were computed among 6 cosine variables and these correlations were then pooled using Fisher's transformation. The relation between circadian variables and 26 daytime behavioral variables were also assessed. We found relatively large long term day to day changes in circadian HR and BT measures, especially HR level. BT level and HR level were correlated, and BT phase and HR phase covaried. Several measures of activity were found to have significant correlations with HR amplitude, while one measure of the nature of the mother-infant relationship was significantly correlated with HR level. It is hypothesized that variability in HR level may reflect long term alterations in autonomic nervous system balance.

An ultrasonic biotelemetry system for the continuous monitoring of tail‐beat rate from free‐swimming fish

A telemetry system for the continuous monitoring of tail beats, and hence swimming activity, from loch‐dwelling brown trout, Salmo trutta L., is described. Tail beats are detected by electromyography and are transmitted using a specially‐developed miniature ultrasonic transmitter. The output from the transmitter is relayed to a remote recording station using a radio‐transponder buoy. Data analysed to date show that on average fish are active for only 9% of the time. Tail beat rates rarely exceeded 2.5 tail‐beats per second (TB/s) corresponding to a velocity of 1 body length per second. The fish showed a ‘preferred’ tail‐beat rate of 1.0–2.0 TB/s and consequently they rarely swam at speeds which would incur oxygen debt.

A modular expandable implantable temperature biotelemeter.

An implantable biotelemetry system is described for multisite temperature measurements with ease of expansion by use of different master circuit boards to accommodate additional channels. Modular construction of the multichannel FM-FM system allows addition or deletion of channels as the experiment requires. The radio frequency carrer osciUlator is tunable to a "quiet" frequency in the 90-105 MHz range prior to implantation. The telemeter may incorporate enclosed or remote temperature probes which allow deep body temperature measurements in the range of 30-42 °C with an available resolution of ±0.015°C. Transmitters have been utilized in monitoring ovarian and subcutaneous temperatures, and also as an aid in detection of ovulation in the Macaca mulatta.

A biobehavioral developmental profile (BDP) for the pigtailed monkey.

AbstractBehavioral development during the 1st 5 months of life was observed in 21 group‐living mother‐reared pigtailed (M. nernestrina) monkey infants. Periodic behavioral observation sessions provided monthly mean scores for 28 different behavioral items. Infants appeared to be separable on several behavioral continua, including their general level of activity and the nature of the mother‐infant relationship. Individual differences were prominent, appeared early and persisted. Patterns of behavior were examined and found to be stable across time.Physiological data (heart rate, body temperature, sleep patterns EEG activity) were collected from 15 of the infants at a mean age of 23 weeks using totally implantable multichannel biotelemetry systems. Group mean values and measures of individual variability were obtained for 23 physiological variables. Physiological variables were correlated with each other and measures of concurrent behavior; the following relationships emerged: Animals with higher body temperatures, both day and night, also tended to have higher heart rates. EEG alpha frequency and alpha ratio (a measure of alpha organization) were positively correlated, meaning animals with higher‐frequency alpha activity tended to have better organized alpha, with less background slowing. Animals with higher alpha frequencies and alpha ratios had more cardiac arrhythmias. Animals with lower body temperatures had longer REM periods and had more Drowsy and less Stage 2 sleep periods, with more frequent awakenings. More active animals had higher body temperatures and heart rates both day and night; animals who rested more had lower body temperatures. Infants that spent more time away from the mother (not in physical contact) appeared to have more cardiac arrhythmias. Infants that were carried more or cradled more by the mother tended to have lower alpha ratios (more slow activity intermixed). More active infants tended to have more Stage 3 4 sleep, less REM sleep, and shorter REM periods than did less active infants. The behavioral data collected during the 1st 4 months of life in the subset of 15 infants were correlated with the subsequent physiological data, and several different types of correlational patterns emerged. Certain physiological variables were highly correlated with behavior during all months, others were highly correlated only with early behavior (e.g., Months 2 and 3) or with lnter behavior (e.g., Months 3 and 4).

QRS wave detection.

A QRS complex detector based on optimum predetection with a matched filter is described. In order to improve the accuracy of the QRS complex recognition under conditions of Gaussian noise and variable QRS amplitude, the first derivative of the e.c.g. was used with zero threshold detection. In addition, two nonlinear circuits cut off low amplitude noise and all spikes which appear for a fixed time after QRS detection. Calculation of errors shows that differentiation reduces Gaussian error by √6 and errors caused by variable QRS amplitudes are close to zero. This detector is especially useful with biotelemetry systems since it reduces many interferences due to patient movement and communication channel distortion.

Nocturnal Sleep in Separated Monkey Infants

Nocturnal sleep was recorded from ten unrestrained, group-living Macaca nemestrina (pigtail) monkey infants, using implantable multichannel biotelemetry systems, during the agitation-depression behavioral reaction that follows maternal separation. Sleep disturbances during the four nights of separation were characterized by decreases in rapid eye movement (REM) time and in the number of REM periods, and increases in REM latency. Time awake and number of arousals were increased. Slow-wave sleep was not significantly affected. Sleep pattern changes were most pronounced the first separation night, and tended to decrease as separation continued, whereas behavioral measures of depression tended to increase as separation continued (up to four days). Sleep patterns returned to normal following reunion with the mother. Those infants who had the most severe sleep disturbances the first separation night (more time awake, less total sleep, less REM) also tended to become most depressed behaviorally later in the separation period.

Physiological correlates of maternal separation in surrogate-reared infants: a study in altered attachment bonds.

Three pigtail infant monkeys (Macaca nemestrina) were separated from their mothers shortly after birth and raised in social isolation on cloth surrogates. At about 24 weeks of age they were surgically implanted with multichannel biotelemetry systems. Following the collection of baseline behavioral and physiological data, the cloth surrogates were removed for 4 days, then returned. The behavioral and physiological (heart rate, body temperature, sleep patterns) reaction to separation from the surrogate was much less intense than is the case in group-living pigtail infants that are separated from their mothers, suggesting that the attachment bond to a cloth surrogate may be different than the bond to a living mother in a social group. Heart rate mean values and variability were similar in surrogate-reared and mother-reared infants, suggesting a degree of environmental independence in heart rate regulation.

Telephone Biotelemetry

This paper is concerned with telephone biotelemetry, such as in the transmission of ECGs or EEGs through telephone networks. It briefly describes the applications of biotelemetry and some research activities in the field. Spectral characteristics and bandwidths of ECG and EEG, and some methods for transmitting these physiological signals through telephone lines are discussed. Shortcomings in the existing telephone biotelemetry systems are identified and some possible solutions to these problems are investigated. The paper is written as a tutorial article directed primarily at clinical engineers, biomedical equipment technicians and other health-care professionals who are interested in the subject.

Nocturnal sleep in isolation‐reared monkeys: Evidence for environmental independence

Thirteen all-night recordings were obtained from 3 infant pigtailed (Macaca nemestrina) monkeys raised on a cloth surrogate mother and under conditions of social isolation. Totally implantable biotelemetry systems were used to record the sleep physiology from the unrestrained animals. Sleep stages and night-to-night variability were virtually identical to values previously found in 8 mother-reared group-living infants. Sustained alterations in the early rearing enviroment, even though considerably modifying the organism's development, did not appear to result in differences in sleep organization.

Design for a micropowered multichannel PAM/FM biotelemetry system for brain research.

A design for a 12-channel pulse amplitude-modulated/FM biotelemetry system is described. The biotelemeter mounts on an animal's head close to the electrode probes to record and transmit brain electrical data. The size of the unit is 4.5 x 6.5 x 2 cm and it weighs about 60 g. It is designed to acquire EEG and other physiological data where the requirement is to obtain bioelectrical activity without cable encumbrance or confining behavioral restrictions. The telemeter consumes about 800 muW of power and operates for approximately 3 continous days before it is necessary to exchange the utilization of complementary metal oxide semiconductor (CMOS) integrated circuits. Transmission range is typically about 10 m.

Multichannel subcarrier ECG, respiration, and temperature biotelemetry system.

A three-channel biotelemetry system measuring ECG, respiration, and body temperature is described. The transmitter employs a 6-kHz subcarrier oscillator and is small enough for surgical implantation in animals the size of rats or larger. The frequency modulated 6-kHz tone from the reciver can be demodulated directly or recorded on an inexpensive cassette tape recorder for future analysis. The transmitter cost is approximately $35.00 and measures 3 times 1 cm. A battery life of several weeks and transmitter range of 10-100 m is typical. Transmission is on the FM broadcast band (88-108 MHz) and reception from an inexpensive FM portable receiver is possible.

An implantable multi-channel biotelemetry system

This paper describes a totally implantable multichannel biotelemetry system developed for recording physiological information from a 20-week-old 800–1000 g monkey infant living unrestrained in its social group. The FM carrier (88–108 Mc/sec) is modulated by a pulse amplitude modulated subcarrier, and transmits EOG, EMG, heart rate, body temperature, and three channels of EEG. The system is constructed by hand from discrete components and commercially available integrated circuits. The total weight of the encapsulated system, including batteries, is 35 g. The effective transmission range using a simple dipole antenna is 10 m, and the transmitter life is 50 days continuous operation. Although designed for use in the infant monkey, the telemetry system would be equally useful in any situation where a requirement exists to record multivariable physiological data from a completely unrestrained and unhampered experimental subject.

Normal physiological patterns and physiological-behavioral correlations in unrestrained monkey infants

Utilizing a totally implantable biotelemetry system, we have recorded normal physiological data simultaneously with behavior in 4 unrestrained M. nemestrina monkey infants, ages 24, 24, 26, and 35 weeks, living with their mothers in their social group. Circadian body temperature rhythms, waking EEG rhythms, sleep patterns, and heart rate measurements were obtained, and were correlated with behavior. Sleep stage values and body temperature circadian rhythms showed relatively little intersubject variability. Heart rate and EEG patterns were more individually characteristic of a given monkey infant. Using both physiological and behavioral data collected in this manner, a bio-behavioral developmental profile for the monkey infant can be constructed. By comparing the infants position with respect to normative physiological and behavioral developmental indices for its chronological age, infants showing bio-behavioral developmental retardation or acceleration in one or several areas can be identified, and the underlying mechanisms investigated. We believe this capability will greatly enhance the value of the infant monkey as an animal model system of value to psychiatry and the behavioral sciences.

A Windowless Si Radiation Detector and Biomedical Telemetry System for Studying the Function of Organs of Free-Ranging Animals

A windowless silicon radiation detector and biotelemetry system has been developed and used in the study of the function of organs of free ranging animals. The system consists of an implantable silicon radiation probe, a transmitter package, an FM receiver, and a data handling unit. The intensity of radioisotopes (RI) taken in the organs is measured continuously with an implantable probe with a 5 mm diameter sensitive area. The transmitter package is composed of an RI signal conditioner, and a transmitter. The prototype transmitter package is made of aluminum, and 2 × 6 × 9.5 cm in size. With electronic components included, it weighs 170 gm. The power consumption of the transmitter is about 100 mW, and is furnished from three 5 V mercury batteries. Two of them are used as the detector bias supply. The system was made of discrete electronic components because of their more reliability, lower operating voltage, and lower power consumption. The fundamental characteristics and field performance of the system were carried out using several dogs with the aid of radioisotopes. The application of the system like the study of liver metabolism of dog is discussed.

Present Status and Resarch Topics of Bio-Telemetry Systems

Present Status and Resarch Topics of Bio-Telemetry Systems

Validity of the Palpation Technique of Heart Rate Determination and its Estimation of Training Heart Rate

Abstract The ability of adult men accurately to count their postexercise heart rate in the course of actual training was determined, and postexercise heart rate estimation with values determined during running were compared. Subjects were 37 men (30–45 years of age), who practiced the palpation technique of counting the carotid or apical pulse prior to data collection. Subjects then ran at a steady heart rate of 80% or 90% of maximum. Heart rates were counted after a 1/2- to 2-mile run. Heart rates were also monitored via biotelemetry and EKG recording systems, and recorded to the nearest 1/2 beat. Care was taken to insure that subjects and investigators had no knowledge of the others' results until after data were recorded. In 252 trials, the difference in estimating running heart rate biotelemetry (171.0 beats/min.) vs. postexercise count by subjects (169.4 beats/min.) was 2.0%. Postexercise values via biotelemetry and subject count (170.1 vs. 169.4 beats/min.) showed a 1% difference. When trials at 90%...

Multichannel Telemetry System for Measuring Body Temperature: Circadian Rhythms of Body Temperature, Locomotor Activity and Oviposition in Chickens

INTRODUCTIONTHE use of biotelemetry systems permits the measurement of physiological information from unrestrained subjects. In addition, if the system is automated, then diurnal records may be taken in the absence of an investigator whose very presence will alter the results (Cain and Abbott, 1970; Cain and Wilson, 1971). The importance of telemetry for physiological rhythm studies has been reported by Miles (1962) and Essler and Folk (1961). Telemetry with birds has included respiration of a flying duck (Lord et al., 1962) and the diurnal heart rate pattern of a chicken (Sturkie, 1963). An implanted telemetry system has also been used to relate time of oviposition and ovulation to changes in body temperature in the chicken (Winget et al., 1965). Many applications of telemetry are described in reviews by Mackay (1968), Ko and Neumann (1967) and Slater (1963). A multichannel AM telemetry and multiplexing system for measuring body temperature circadian…

Biotelemetry as a Technique in Disease Ecology Studies

Disease ecology studies frequently demand a detailed knowledge of movements and activity patterns of infected animals, base-line data from apparently healthy individuals and/or inter-action rates between hosts. Additionally, some investigations require periodic examinations of hosts and the recovery of dead animals for necropsy. Until quite recently these data have been obtained primarily by live trapping and marking animals, systematic collections of specimens, or, as in the case of rabies, reports of state public health or veterinary diagnostic laboratories. All of these approaches present difficulties which may limit the quality or quantity of the information gained. For example, the technique of live trapping requires the assump- tion that movement and activity parameters are not affected by the experimental procedures. Balph ( 1968 ) , however, has shown that ground squirrels may become trap happy in response to a ready source of food or trap shy as a result of the noxious experience of being captured and handled. Similarly information obtained from systematic collections of specimens and from laboratory diagnostic reports frequentlyprove to be of limitedvalue in unravelingthe ecologicalrelationships of disease complexes. The technique of attaching miniature radio transmitters to free ranging wild animals, or biotelemetry, may prove to be quite useful in disease investigations by reducing or eliminating the above limitations and by providing more data per unit effort than are provided by current techniques. A properly designed biotelemetry system enables the investigator to determine, with minimal disturbance, behavior patterns of unconfined wild animals. It also provides for determination of the time of death of radio-marked animals and thus permits immediate collection of the remains for necropsy. Houseknecht (1969) used this technique to determine the denning habits of striped skunks (Mephitis mephitis) and the resulting exposure potential for disease. By quickly retrieving carcasses of succumbed radio-marked fawns (Odocoileus virginianus), Cook et a!. (1967) determined the cause of death in 49 of 58 cases. The capability of continuously monitoring the location of radio-marked animals also permits examination of hosts or the collection of specimens at will. Montgomery (1968) attached radio collars to a white-tail deer fawn then recaptured the animal at predetermined intervals in order to investigate the rate of tick attachment. Simi- larly one could recapture radio-marked striped skunks for monthly bladder traps for an investigation into the ecology of leptospirosis. The technique of biotelemetry has been employed in animal movement studies since 1959. These first transmitter packages (Le Munyan et a!., 1959) measured 7.5 x 4.0 x 1.4 cm, weighed 122.5 gm and were designed for implantation into the