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At least 973 records · Page 54Linked to original sources

PubMed2006

Diurnal variations of blood pressure in cats.

Blood pressure (BP) was analyzed invasively using the telemetry system in unanesthetized, unrestrained healthy adult mongrel cats. After surgical implantation of a telemetry transmitter, BP was transiently elevated due to the invasive nature of the surgery, but it was gradually decreased. BP was largely stabilized seven to ten days postsurgery. Once BP was settled, systolic, diastolic and mean BPs(2) were obtained at 5-min intervals in individual cats. Hourly averages of these BP values revealed a diurnal variation with two peaks at 8:00 and 19:00. We also found that BP was significantly higher when cats were active compared to when they were sleeping or at rest (p<0.05). The average 24-hr BP in 20 healthy cats was 118.4+/-11.0 (systolic), 78.0+/-8.7 (diastolic) and 94.8+/-9.5 mmHg (mean) by the telemetry system.

Animals↗

PubMed1994

[Telemetric transmission system for in vivo measurement of the stress load of an internal spinal fixator].

For stabilizing fractures of the spine, a number of implantable devices are available. However, not much is known about the loads acting on these devices. In order to measure the forces and moments within the implant, the Dick internal fixation device was modified and fitted out with a hermetically sealed inductively powered telemetry unit. An integrated 8-channel telemetry chip was specially developed to measure the signals of six strain gauge sensors, the temperature of the implant and the supply voltage. Since the internal fixation devices are always implanted in pairs, two telemetry units are operated at the same time. This article details the function of the implanted electronic circuit and the external system components.

Adult↗

PubMedDate not supplied

Physiologic monitoring systems.

Physiologic monitoring systems, which monitor vital physiologic parameters so that clinicians can be informed of changes in a patient's condition, typically consist of several distinct components, including a central station, bedside monitors, and ambulatory telemetry transmitters and receivers. For this study, rather than focusing on how each component performs individually, we evaluated how the entire system functions as a whole to better parallel the acquisition practices followed by most hospitals. We evaluated systems from eight suppliers, focusing primarily on adaptability, alarm implementation, and human factors design. We included only systems that offer (1) a central station that can concurrently receive information from bedside monitors and ambulatory telemetry transmitters, (2) one or more bedside monitors that can be used in critical care and intermediate care areas, as well as during transport, and (3) ambulatory telemetry monitoring. We rated the evaluated systems based on their capabilities for each of six applications: critical care unit, emergency department, intermediate care unit and general medical/surgical floor, operating room, postanesthesia care unit, and transport. We found that many of the systems are suitable for some applications, but are unable to meet the requirements for others.

Computer Systems↗

PubMed1975

Telemetered renal responses in dogs during detection of explosives.

The primary objectove of this work was to develop and test a method of measuring and characterizing renal hemodynamic responses in unrestrained dogs. Recordings of left kidney blood flow and abdominal aortic pressure were obtained from unrestrained dogs through the use of a two-channel implanted telemetry system during episodes of search and detection of simulated explosives. In each of a number of sequences, the dog was first given a start signal, and after locating the hidden device, was rewarded with food. Data were assessed at the start, find, and recovery segments. The dynamic flow and pressure, together with a hydraulic renal model, were used to derive the total preglomerular and postglomerular vascular resistances and the mean level of glomerular hydrostatic pressure. Data from three dogs obtained by telemetry and analyzed through the use of the model have shown that compared to the start of the test, the location of hidden explosives results in a decrease in both the level of mean aortic blood pressure and the preglomerular resistance; whereas, the reward results in an elevation of mean blood pressure and preglomerular resistance. The postglomerular resistance varied less than the preglomerular resistance, and mean flow did not vary significantly. This work has shown that the stimulation of a reward and the successful performance of a task lead to significant renal responses in dogs. It has further shown that telemetry, when employed with improved data analysis techniques, permits renal hemodynamics to be assessed in unrestrained animal subjects.

Animals↗

PubMed1992

Video EEG analysis of non-ictal events in children.

Over a 3 year period 186 children aged 3 weeks to 17 years were studied by telemetry (prolonged video and EEG monitoring) at the Prince of Wales Children's Hospital: 74 had events considered at referral to possibly represent seizures but which were shown by clinical analysis and telemetry to be non-ictal. Nine such patients were developmentally delayed, one was neurologically impaired and 16 were both developmentally delayed and neurologically impaired. A specific diagnosis of the non-ictal events was reached in 24 subjects-postures of spasticity in children with neurological impairment (6), Münchausen-by-proxy (5), pseudoseizures (3), breathholding (2), masturbation (2), reflux (2), shudder (1), movement disorder (1), motor tic (1) and pertussis (1). Specific descriptive patterns were assigned to the remaining 51 events. These included staring (20) and jerks (16) or unusual behaviour (15). 49 inter-event EEGs were normal; 7 displayed abnormal background rhythms and 19 showed epileptiform activity. We discourage use of the term 'pseudoseizure' for the majority of the events described and prefer that a specific diagnosis be made or a descriptive analysis be provided. The events seen illustrate the wide spectrum of childhood behaviour and on occasions suggest the need for telemetry to determine their true nature.

Adolescent↗

PubMed2004

Electrophysiologic and objective monitoring of the cochlear implant during surgery: implementation, audit and outcomes.

Electrophysiologic and objective measures are reviewed with respect to their implementation as monitoring tools for cochlear implants in the operating room and their value in the management of children. The current intraoperative test protocol in Nottingham consists of back-telemetry (BT) diagnostic testing of implant function, including impedance telemetry (ImpT), integrity testing (IT), electrical stapedius reflex response (ESR), electrical auditory brainstem response (EABR) and Neural Response Telemetry (NRT). Of 427 cases of implantation in the period 1990-2003, 303 (71%) were completely normal for all components of the protocol. In the remaining cases, some results were either simply anomalous, with no direct impact on management during surgery, and some were more significant, resulting in actions such as the use of the back-up device or repositioning of the electrode array. Normal intraoperative findings provided immediate reassurance to the implant team and parents of young children that the implant was fully functioning and that electrical stimulation was activating the auditory pathways These objective measures also identified potentially challenging cases, such as those with low levels of sensitivity to electrical stimulation and susceptibility to facial nerve stimulation. An audit showed that intraoperative measures provided valuable assistance in the initial fitting of the device.

Action Potentials↗

PubMed1979

Totally implantable directional Doppler flowmeters.

Two totally implantable Doppler blood flowmeters have been developed for the chronic measurement of deep-body flows; made possibly by two custom-integrated circuits. The CW and pulsed Doppler instruments are small (less than 2.5 cm3), use little power (less than 30 mW), and have excellent baseline stability. The pulsed Doppler flowmeter is applied principally when velocity-profile information or a nonencircling transducer assembly is required but where minimal restraint of the animal for inductive telemetry is permissible. Using a circumferential cuff, the CW Doppler flowmeter monitors Doppler data over a at least a 3-meter range by means of RF telemetry and produces a single velocity estimate. These instruments compliment each other and other telemetry systems by proving the researcher with alternatives for the long-term measurement of deep-body flow without percutaneous leads.

Animals↗

PubMed1992

Heart rate monitoring of physical activity in children and adolescents: the Muscatine Study.

To assess the usefulness of whole-day heart rate monitoring as a quantitative measure of physical activity in children, the activity of 76 children and adolescents (ages 6 to 17 years), randomly selected from a school population, was measured during a typical summer day using a light-weight, nonrestrictive heart rate telemetry unit. A 12-hour recall and a simple self-rating of usual activity questionnaire were also administered on the same day. An additional 12-hour recall questionnaire was administered on another day. Within 1 month of the heart rate monitoring, the skinfold measures, peak aerobic capacity, and sexual maturation were assessed. Data analysis indicated that activity as measured by telemetry was related to questionnaire recall on the monitored day (r = .50), nonmonitored day (r = .32), and self-rating (r = .35); level of activity as measured by telemetry was related to peak aerobic capacity in girls (r = .36) but not in boys (r = -.06); body fat was related inversely to activity (r = -.32); and prepubescent children were more active than post- and pubescent children (P less than .003). No difference was found in activity level between boys and girls (P greater than .05). This study suggests that for children whole-day heart rate monitoring is an objective, nonobtrusive method for measuring physical activity; and maturation, but not gender, is an influential mediating factor for activity.

Adolescent↗

PubMed1991

Theory and application of diffuse infrared biotelemetry.

For biomedical applications the most significant is diffuse indoor infrared telemetry. The advantages and disadvantages of infrared diffuse biotelemetry in comparison to RF biotelemetry are presented. Design of the transmitter-receiver link is described and it is shown how efficiency coefficient of the link can be optimized. The whole room can be covered with infrared radiation because of room wall reflections. The distribution and reflections of infrared radiation are analyzed to calculate their most significant parameters and compare them with measured data. One very efficient infrared telemetry system is described and its characteristics are given. To realize a multichannel system inside one room, an asynchronous and a synchronous mode are feasible. The asynchronous mode is characterized with simplicity but the number of channels is very limited. However, the synchronous mode is more sophisticated and complex but acts as a multichannel system without any interference between channels. The realization of both systems is described. In the case that the infrared radiation in some part of the room is not sufficient, an infrared relay can be applied. At the end, a survey of the infrared telemetry application in medicine is given.

Electronics↗

PubMed1985

Amplification and transmission of the EEG.

In long-term monitoring of the EEG in epilepsy, the recording conditions are usually such that a technique must be used which allows EEG recording from patients who are engaged in behavioral activities. The technique employed basically consists of the use of a miniaturized EEG amplifier at the site of the patient and the transmission of the amplified EEG to the recording apparatus. As regards the quality of the recording, the use of miniaturized amplifiers involves various problems, particularly those related to the choice of the fixed amplifier characteristics. Depending on the recording conditions, the transmission is commonly carried out whether by cable telemetry or by radio telemetry. Various techniques for multi-channel data transmission can be used for both telemetry methods. The choice of any particular transmission technique will mainly depend on the characteristics of the EEG data transmitted and on specific requirements on the quality of the recording.

Amplifiers, Electronic↗

PubMed1985

Monitoring at the Instituut voor Epilepsiebestrijding Meer en Bosch.

A requirement for intensive epilepsy monitoring arose from a demand for ictal EEG registration for diagnostic purposes and in the context of pharmacokinetic research. The monitoring facility developed gradually: first conventional EEG equipment was used on the wards, later miniaturized pre-amplifiers were introduced to allow the patient greater freedom, finally a comprehensive specialized monitoring facility was created with its own accommodation. For most clinical and research applications arising in the Institute intensive observation and video monitoring are necessary. The greater reliability, channel capacity and bandwidth of cable telemetry offer considerable advantages over alternative monitoring techniques as radio telemetry. For recording from patients in locations outside the monitoring unit but where restricted mobility is acceptable a combination of telephone telemetry with a local radio link is used. Synchronization of EEG and video images is achieved by various means, depending on the application: split-screen technique, superimposition of EEG on video images or annotating the paper EEG chart with digital time information derived from the video time-date generator. Buffering of EEG signals is also available by means of a computer disk or a shift register. During the development of the system evaluation studies have been performed showing a progressively increasing yield of clinically useful information. At the most recent assessment, 79% of the investigations answered the clinical question addressed, in 65% of instances the findings had consequences for management and in over 25% the decisions resulting from monitoring had long-term therapeutic benefits for the patient.

Automation↗

PubMedDate not supplied

A completely implanted left ventricular assist device. Chronic in vivo testing.

A completely implantable left ventricular assist device (LVAD) designed for permanent circulatory support has recently been tested in animals without the use of percutaneous leads, using transcutaneous energy transmission and wireless telemetry. The LVAD consists of a brushless DC motor and rollerscrew energy converter, a pusher plate actuated blood pump with a seamless segmented polyurethane blood sac, Bjork-Shiley Delrin disk monostrut valves, an implanted compliance chamber, an implanted electronic controller and battery, and a transcutaneous energy transmission system. The blood pump/energy converter assembly weighs 565 g and displaces 295 cc. The dynamic stroke volume is 60 ml, and the maximum output is 9 L/min. Pump output is automatically controlled to maintain full stroke volume as preload varies. Hall effect sensors for detecting rotary position of the motor are the only sensors used. Six bovine implants were performed, with durations of 84, 208, 244, 130, 70 (ongoing), and 15 (ongoing) days. Four animals used two-way telemetry, whereas the remaining two used one-way (outgoing) telemetry. These first chronic in vivo tests with the Penn State completely implanted LVAD system have demonstrated that it is a feasible solution to long-term ventricular support.

Animals↗

PubMedDate not supplied

[Comparative analysis of the effects of clonidine preparations depending on methods of arterial pressure recording].

Changes in hemodynamic parameters in intravenous infusion of drugs of the clonidine group were studied in Wistar rats by means of the radio-telemetry and catheter systems of arterial pressure (AP) recording. Clonidine (5 micrograms/kg), rilmenidine (300 micrograms/kg), and moxonidine (100 micrograms/kg) were found to cause significant decrease in AD and bradycardia whatever the method of AD measurement used. However, the degree of the hypotensive and negative cardiochronotropic effects of the central action drugs was higher in rats with radio-telemetry transmitters. The results provide evidence that the radio-telemetry system of monitoring of the hemodynamic parameters is more sensitive and accurate for evaluating the effect of the drugs under study.

Animals↗

PubMed2000

Treatment of underlying atrial fibrillation: paced rhythm obscures recognition.

OBJECTIVES: The purpose of this study was to evaluate the rate of recognition of atrial fibrillation (AF), use of warfarin and prevalence of cerebrovascular accident (CVA) in paced versus unpaced patients during admission to a tertiary care teaching hospital. BACKGROUND: The presence of AF underlying a continuously paced rhythm may be under recognized and result in a lower rate of anticoagulation and higher incidence of CVA. METHODS: The identification of AF on 12 lead electrocardiogram (ECG) and telemetry, "optimal use" of anticoagulants that is, warfarin or aspirin, when warfarin is contraindicated and history of prior CVA was studied in three groups: 1) group A with continuously paced rhythm on ECG and telemetry (n = 30), 2) group B with intermittently paced rhythm on ECG and telemetry (n = 59), and 3) group C with persistent AF and no permanent pacemaker (n = 50). RESULTS: The identification and documentation of AF was significantly lower in the continuously paced group A (20%) versus the intermittently paced group B (44%). Both groups A and B were substantially lower than unpaced controls. "Optimal use" of anticoagulants was significantly lower in group A (40%) compared with groups B (78%) and C (72%) but was not different between groups B and C. The prevalence of prior CVA was not significantly different between the three groups. CONCLUSIONS: All ECGs in patients with paced rhythm should be examined closely for underlying AF to prevent under-recognition and under-treatment with anticoagulants.

Aged↗

PubMed2005

Wireless sensors powered by microbial fuel cells.

Monitoring parameters characterizing water quality, such as temperature, pH, and concentrations of heavy metals in natural waters, is often followed by transmitting the data to remote receivers using telemetry systems. Such systems are commonly powered by batteries, which can be inconvenient at times because batteries have a limited lifetime and must be recharged or replaced periodically to ensure that sufficient energy is available to power the electronics. To avoid these inconveniences, a microbial fuel cell was designed to power electrochemical sensors and small telemetry systems to transmit the data acquired by the sensors to remote receivers. The microbial fuel cell was combined with low-power, high-efficiency electronic circuitry providing a stable power source for wireless data transmission. To generate enough power for the telemetry system, energy produced by the microbial fuel cell was stored in a capacitor and used in short bursts when needed. Since commercial electronic circuits require a minimum 3.3 V input and our cell was able to deliver a maximum of 2.1 V, a DC-DC converter was used to boost the potential. The DC-DC converter powered a transmitter, which gathered the data from the sensor and transmitted it wirelessly to a remote receiver. To demonstrate the utility of the system, temporal variations in temperature were measured, and the data were wirelessly transmitted to a remote receiver.

Bioelectric Energy Sources↗

PubMed2003

Measuring energy expenditure in habitually active and sedentary pregnant women.

PURPOSE: To describe patterns of energy expenditure (EE) during pregnancy and to assess the convergent validity of three methods of estimating EE. METHODS: We administered heart rate (HR) telemetry, accelerometry, and a physical activity record (PAR) over two consecutive days at weeks 20 and 32 of pregnancy and 12 wk postpartum to 28 habitually active and 28 habitually sedentary women. RESULTS: Mean daily waking-time EE at 20 wk by HR telemetry was 1814 (SD 443) kcal in active women and 1738 (448) kcal in sedentary women (P > 0.50), and did not change over the period of study (for active women P > 0.40; for sedentary women P > 0.70). Compared with HR telemetry, accelerometry underestimated EE by approximately 400 kcal x d-1, and the PAR overestimated EE by a similar amount, at all time periods in both active and sedentary women. EE, expressed per unit body weight, was consistently higher for active than for sedentary women during pregnancy. Pairwise correlations between methods ranged from 0.37 to 0.90 across time periods in both active and sedentary women. Correlations were lower (range 0.07-0.81) when adjusted for the length of the recording day. CONCLUSIONS: All methods were sensitive to variation in both the rate of EE and the duration over which activity was monitored. Accelerometry and PAR are useful methods for categorizing EE in epidemiologic studies among pregnant women but absolute estimates are biased relative to HR.

Adult↗

PubMed2003

Effects of irradiation on the components of implantable pacemakers.

The purpose of this study was to examine the effects of irradiation on implantable pacemaker components. The pacemaker was divided into three components: lead wire and electrode, battery, and electrical circuit, and each component was irradiated by X-ray and electron beams, respectively. The pacemaker parameters were measured by both telemetry data of the programmer and directly measured data from the output terminal. The following results were obtained. For the lead wire and electrode, there was no effect on the pacemaker function due to irradiation by X-ray and electron beams. In the case of battery irradiation, there was no change in battery voltage or current up to 236Gy X-ray dose. In the electrical circuit, the pacemaker reverted to the regular beating rate (fixed-rate mode) immediately after the start of X-ray irradiation, and it continued in this mode during irradiation. In patients with their own heartbeat rhythm, changing to the fixed-rate mode may cause dangerous conditions such as ventricular fibrillation. When the accumulated irradiation dose is increased, another failure can be seen in the output voltage of the pacemaker. The pacing output voltage dropped rapidly by about 40 % at 30-88Gy. Decreasing the output voltage results in pacing disorders, and heart failure may occur. In the telemetry data of the programmer, no change in output voltage could be detected, highlighting the difference between telemetry data and actual pacing data.

Electrodes, Implanted↗

PubMed2002

Naturally occurring variation in cardiovascular traits among inbred mouse strains.

The objective of this study was to characterize genetic variation in complex cardiovascular traits in two commonly used inbred mouse strains. We performed echocardiography, graded treadmill exercise, tail cuff plethysmography, and telemetry (heart rate, activity, temperature) in age- ( approximately 9 weeks) and sex-matched A/J and C57BL/6J (B6) inbred mice. B6 mice had significantly larger end-diastolic dimension (3.31+/-0.42 mm versus 2.83+/-0.31 mm) and left ventricle mass (46.2+/-14.1 versus 32.7+/-11.5 g) than A/J mice. This relative hypertrophy was eccentric (relative wall thickness ratios: 0.30+/-0.01 versus 0.32+/-0.01) and was not associated with a difference in systolic blood pressure (122.0+/-13.2 versus 123.1+/-20.8 mmHg). Left ventricle fractional shortening (39.1+/-6.2 versus 47.1+/-6.9%) and heart rate (433+/-55 versus 524+/-45 beats per minute) were significantly lower in B6 versus A/J, respectively, resulting in similar resting echocardiographic cardiac indices (0.58+/-0.19 versus 0.50+/-0.17 ml/min/g). Maximum exercise time on a treadmill was significantly greater in B6 than in A/J mice (9.6+/-3.4 versus 4.4+/-1.9 minutes). Telemetry showed that body temperature was generally greater and heart rate lower in B6 than A/J; the relation with activity was more complex. These data suggest that relative to A/J, B6 mice have a phenotype characteristic of the "athlete's heart," that is, eccentric, physiologic hypertrophy, slower heart rates, and increased exercise endurance. This systematic characterization of functionally related cardiovascular traits in A/J and C57BL/6J mice revealed numerous differences whose genetic bases can be dissected with recombinant inbred, recombinant congenic, and chromosome substitution strains.

Animals↗