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At least 109 records · Page 6Linked to original sources

Computerized home telemetry of maternal blood pressure in hypertensive pregnancy.

We have developed a telemetric technique whereby maternal blood pressure, which is self-measured by pregnant women in their own homes using a Dinamap 1846 automated blood pressure recorder, can then be transmitted over the commercial telephone network into the Rosie Maternity Hospital in Cambridge, where it is computer-processed. The maternal blood pressure is then reviewed by the obstetrician as part of the clinical management protocol. We have used this telemetric technique on 90 occasions, from the homes of 10 pregnant hypertensive women. On almost every occasion, the blood pressure measured at home was lower than that previously measured in the hospital antenatal clinic. This technique offers great promise, both in terms of health economics and also in terms of reducing pregnant women's unhappiness about their being admitted to hospital whenever they exhibit moderate to severe hypertension in the antenatal clinic. Indeed, in the antenatal period, home telemetry should allow the vast majority of hypertensive pregnancies to be managed just as safely at home as in hospital. In the management of high risk pregnancy, home telemetry of maternal blood pressure complements three other home telemetric techniques which have already been described: fetal heart rate, maternal blood glucose and uterine contractions.

Adult↗

Longterm heartrate telemetry in small mammals: a comprehensive approach as a prerequisite for valid results.

This paper describes a miniature telemetry system which is capable of precise, reliable longterm registration of heartrate (HR) in animals as small as laboratory mice. The ECG-transmitters have a weight of 0.9-1.5 g and a respective lifetime of 3-6 months depending on battery size. With suitable receiving antennas, transmitting range is sufficient for continuous reception in 200 m2 enclosures. The radio signals are demodulated in a signal processor and the ECG is converted to HR on the base of single interbeat intervals. General technical problems of telemetry like miniaturization, performance control, HR acquisition and artifact distinction are discussed. The experimental approach emphasizes the necessity of continuous registration of HR as a reference for experimental responses. Longterm shifts of HR due to social and nonsocial influences as well as experimental feedback effects are demonstrated and discussed.

Animals↗

Circadian rhythms of blood pressure, heart rate, and locomotor activity in spontaneously hypertensive rats as measured with radio-telemetry.

Circadian rhythms of blood pressure, heart rate, and locomotor activity were measured with implanted radio-telemetry transmitters in conscious, unrestrained spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). During the light period (0600 to 1800 h) systolic, diastolic, and mean blood pressure, heart rate, and locomotor activity were lower than during the dark period (1800 to 0600 h). During the first and the last hour of the dark period, all parameters showed a relative peak when compared to values during the rest of the night. The pattern of circadian changes in blood pressure, heart rate, or behavior was essentially similar in SHR and WKY. Blood pressure values were always higher in SHR than in WKY, but there was no general strain difference in heart rate or locomotor activity values. The administration of hydralazine in the drinking water resulted in a significant decrease in blood pressure in SHR and WKY, and a suppression of the difference between light-phase values and dark-phase values. By contrast, heart rate showed an overall increase in both strains, whereas locomotor activity was largely unaffected. These data show the validity of telemetry as a means of measuring circadian rhythms of blood pressure, heart rate, and behavior in freely moving rats. Apart from their characteristic hypertension, SHR show few differences with WKY with respect to other parameters, such as circadian rhythmicity, baseline heart rate values, or behavior. Some of the previously published differences between SHR and WKY may have been influenced by the stress of the experimental procedures used.

Animals↗

Monitoring guinea pig core temperature by telemetry during inhalation exposures.

A temperature telemetry system was incorporated into an existing animal model for inhalation toxicology. This system facilitated continuous monitoring of guinea pig temperature during inhalation exposures. Components of the system included Mini-Mitter temperature-controlled oscillators, AM receivers, and an IBM microcomputer. Software was developed to perform signal processing and filtering. Transmitters were calibrated and then sterilized and surgically implanted in the guinea pig peritoneum. Monitoring the baseline temperature of nine animals indicated a mean temperature of 38.6 +/- 0.3 degrees C. Guinea pigs were treated with agents to induce transient hypo- or hyperthermia. For the former, exposure for 3 hr to 7.8 ppm diphenylmethane-4,4'-diisocyanate resulted in a 3 degrees C temperature decrease. The temperature was determined from 230 readings per animal per hour. Inhalation of 9 or 44 micrograms/m3 endotoxin for 6 hr induced hyperthermia with a 1.5 degrees C maximum increase in core temperature at 4.8 hr. With endotoxin, an increase in respiratory rate was also noted and followed the same pattern as temperature with a maximal increase of 52% occurring at 4.2 hr. The temperature telemetry system enabled continuous long-term monitoring of toxicant-induced hypothermia and pyrexia without interruption of inhalation exposure or measurements of respiratory parameters.

Administration, Inhalation↗

Changes in the serotonergic system during the sleep-wake cycle: simultaneous polygraphic and voltammetric recordings in hypothalamus using a telemetry system.

Changes in the serotonergic system in the posterior hypothalamus of freely moving rats were related to sleep and wakefulness using in vivo voltammetry (with carbon fiber microelectrodes) and polygraphic recordings. By using an optoelectronic telemetry system for the voltammetric signals, electrical cross-talk between the two settings was avoided and simultaneous neurochemical and electro-physiological recordings could be made so that a detailed time course of events could be obtained. Extracellular levels of the serotonin metabolite, 5-hydroxy-indoleacetic acid, measured every 2 min, increased with wakefulness and decreased with sleep: levels were significantly lower during desynchronized sleep than slow wave sleep. In vivo voltammetry associated with the optoelectronic telemetry system appears to be a useful tool for studying the relationship between neurochemical changes and electrophysiological events.

Animals↗

Prehospital care telemetry--how essential?

The telemeterized ECG, once a necessary and important part of prehospital care, may now be an unnecessary, expensive luxury. Paramedic training now produces a professional capable of diagnosing ECG rhythms as accurately as emergency physicians. ECG telemetry may, however, have utility for esprit de corps, training, evaluation, and supervision of new or less trained paramedics. Recommendations for establishing or renewing community telemetry systems are made.

Arrhythmias, Cardiac↗

Evaluation of a new method using telemetry for monitoring the left ventricular pressure in free-moving rats.

Left ventricular pressure (LVP) in free-moving rats was continuously measured for 2 weeks by a telemetry blood pressure measurement system. Prior to LVP measurement, a dummy transmitter was used to determine whether organ weights, including that of the heart and the lungs, or the stiffness of the left ventricular chamber were affected by the catheterization of the LV chamber. Organ weights did not increase, and no functional abnormalities were observed in the left ventricular pressure-volume relationship. The LVP transmitter was implanted in the left ventricle, and systolic LVP, end-diastolic LVP, LV dP/dt max, and heart rate were measured. All parameters were essentially stable during the 2-week observation period after implantation, and the values, especially the heart rate, in the dark phase tended to be higher than those in the light phase. Microscopic examination of the left ventricular wall revealed that implantation of the dummy or LVP transmitter caused no histological damage. We confirmed that LVP in free-moving rats can be measured continuously for 2 weeks without any harmful effect on cardiac function and that this telemetry system should be useful in pharmacological and toxicological studies.

Animals↗

Vaginal temperature sensing using UHF radio telemetry.

User-induced errors are common when women repetitively employ conventional probe type thermometers to chart their basal body temperatures in an effort to indicate ovulation. An alternative technique employing a two-part telemetric thermometer is proposed, with low-power, SAWR-controlled UHF radio as the transmission medium. Worn overnight in the vagina, the 1 microW erp telemetry transmitter sends pulse modulated data continuously to a microcontroller in a nearby receiver; a real time clock enables programmable sampling and storage of the subject's temperature to 0.1 degrees C resolution. Initial clinical results indicate an enhanced performance compared to oral and axillary temperature trends taken by a mercury-in-glass thermometer. Polar plots of both the isolated and body-worn telemetry transmitter are presented; body induced attenuations of up to 30 dB were measured.

Biomedical Engineering↗

Prevalence of life-threatening arrhythmias in ED patients transported to the radiology suite while monitored by telemetry.

OBJECTIVE: The aim of this study was to determine the prevalence of life-threatening arrhythmias in monitored ED patients while in the radiology suite. METHODS: This is a retrospective analysis at a tertiary care hospital with an ED census of 52,000 visits. The patient population consisted of 3,051 adult ED patients with a chief complaint of chest pain, who were monitored with telemetry while they were sent to the radiology suite, and who were ultimately admitted to the hospital. RESULTS: Of a total of 3,051 consecutive patients with a cardiac presentation who received a nonportable chest x-ray, no patients were found to have incurred a life-threatening arrhythmia while in the radiology suite. CONCLUSION: The prevalence of a cardiac arrhythmia occurring during transport or while within the radiology suite in our study was zero. We conclude that stable patients can probably be transported to radiology safely without the use of bedside telemetry.

Arrhythmias, Cardiac↗

Impact of stress testing on 30-day cardiovascular outcomes for low-risk patients with chest pain admitted to floor telemetry beds.

The role of immediate stress testing in low-risk patients with a potential acute coronary syndrome has not been rigorously evaluated with respect to impact on 30-day cardiovascular events. We evaluated the impact of inpatient, outpatient, or no stress testing (ETT) on 30-day cardiovascular outcomes. We performed a prospective cohort study in which consecutive patients with chest pain were admitted to a non-intensive-care telemetry bed over 16 months. Patients were identified in the ED, followed daily through hospitalization, and contacted by telephone at 30 days. Patients were excluded if they were admitted to the coronary care unit, died during hospitalization, sustained an acute myocardial infarction (AMI), or received cardiac catheterization before ETT. Patients were stratified according to whether they received an ETT as an inpatient, outpatient, or no ETT. Main outcomes were 30-day cardiac death, AMI, percutaneous interventions (PCI), and coronary artery bypass graft surgery (CABG). Data are presented as percentages with 95% confidence intervals (CI) for main outcomes. A total of 832 patients were admitted 962 times. A total of 205 patients (21%) received an in-house ETT. Seventy-four patients (10%) without an inpatient ETT received an outpatient ETT. At baseline, the groups were similar with respect to likelihood of ischemia based on mean ACI-TIPI score and Goldman risk score. A total of 98% of patients had 30-day follow-up. The cardiovascular outcomes (with 95% confidence interval) for patients with inpatient ETT versus outpatient ETT versus no ETT were as follows: death, 0% (0-1.5%) vs 0% (0-4.1%) vs 1% (0.3-1.7%); AMI, 1% (0.1-2.4%) vs 1.4% (0.1-4.1%) vs 0.3% (0.1-0.7%); PCI, 0.5% (0.1-1.5%) vs 1.3% (0.1-4.1%) vs 0% (0-0.4%); and CABG, 0.5% (0.1-1.5%) vs 0% (0-4.1%) vs 0.2% (0.1-0.4%). There was no statistical difference in 30-day cardiovascular outcomes among patients who received inpatient, outpatient, or no ETT within 30 days. This suggests that patients with chest pain who are admitted to non-intensive-care telemetry (or observation unit) beds might not need stress testing before hospital release.

Chest Pain↗

Effects of rhIGF-I and insulin-induced hypoglycaemia on cardiovascular parameters recorded with telemetry in the conscious dog.

Using telemetry, the effects on cardiovascular parameters after single intravenous administration (0.5 mg/kg) of recombinant human insulin-like growth factor-I (rhIGF-I) were studied in conscious and unrestrained dogs. Insulin (1.1 IU/kg) was used as a reference compound. Telemetry transmitters were implanted subcutaneously with a pressure catheter in the femoral artery and electrodes for ECG subcutaneously. Cardiovascular effects and changes in blood glucose levels induced with rhlGF-I were similar to those induced with insulin. Heart rate increased continuously for about 90 min. after treatment, regardless of compound. Thereafter, heart rate slowly decreased but did not fully reach predose values 4 hr after treatment. Both systolic and diastolic blood pressure decreased continuously for about 90 min. and remained low for up to 4 hr after treatment. Treatment with rhIGF-I or insulin did not influence dp/dt values. Treatment with glucose intravenously to abolish the rhIGF-I-induced hypoglycaemia reduced the heart rate, but caused a substantial increase in dp/dt and a slight increase in blood pressure. RhIGF-I and insulin induced an almost identical onset and degree of hypoglycaemia. Blood glucose reached a minimum level 1 hr after treatment and was almost returned to normal 4 hr after treatment. There was an increase in the amplitude of the T-waves, though this effect occurred earlier and was longer lasting with insulin than with rhIGF-I. After 4 hr, the T-wave amplitude was normal with rhIGF-I but remained high with insulin. These T-wave effects were probably due to an increase in the transport of potassium or calcium since they decreased in plasma. This suggests that the effects of rhIGF-I and insulin are highly comparable and that the cardiovascular changes induced by rhIGF-I are likely caused by its insulin-like activity. As shown by the recorded cardiovascular responses induced by rhIGF-1 and insulin, the telemetric recording system makes it possible to evaluate the effects of different drugs in a continuous way that is not possible with conventional techniques. This new telemetric technique can be of significant importance in the process of future drug development.

Animals↗

The effects of triiodothyronine (T3) on heart rate, temperature and ECG measured with telemetry in freely moving mice.

We have set up a telemetry system and recorded heart rate, electrocardiogram (ECG), body temperature and the locomotor activity in awake freely moving mice. The telemetry system (DATA Sciences, St Paul, MN, USA) comprises a transmitter implanted in the peritoneal cavity and a receiver (RA1010) placed underneath the home cage. The signal from the transmitter includes the electrical activity of the heart and the body temperature. The results show that four days after the surgical procedure the mice have recovered and regained a clear circadian rhythm. The heart rate varied under baseline conditions between 432 and 618 beats min-1 and the body temperature between 35.1 and 37.7 degrees C (based on 60 min mean values). A clear time correlation between heart rate, body temperature and locomotor activity was found. As an evaluation of the method we injected T3 s.c. during a period of 4 days. Further, we were interested in whether it was possible to measure an integrated physiological response to T3 and further investigate the time course for the effect. After one day of treatment with triiodothyronine there was a significant increase in body temperature and locomotor activity. The increase in heart rate was seen after 2 days. The ECG recording revealed a significantly shortened QTend- and QRS-time. No significant difference in the PQ-time was found. This method may be of great importance in studies of genetically manipulated mice.

Animals↗

Incidence of occlusal contacts with complete dentures during mastication using a 6-channel telemetry system: preliminary measurements.

The purpose of this study was to observe the incidence of occlusal contact with complete dentures during mastication using a 6-channel telemetry system whose accuracy had been improved. The telemetry system consisted of the transmitter unit and the receiver unit. The transmitter unit was embedded in the lower complete denture. This system detects occlusal contacts by the shift of frequency in 100 kHz. The transmitter allowed 6 channels for the occlusal contacts. The data was telemetered by a time division multiplex communication method. A special switch was designed to measure excursive movement on the occlusal surface. After careful occlusal adjustment, the special switches were inserted in the lower first molars. On the basis of preliminary measurements on a 64-year-old edentulous male, it appears that the width of the gliding on the occlusal surface at the lower first molar was mostly 0.2-1.2 mm and the majority of the excursive movements ended at the centric occlusal position.

Dental Occlusion↗

Continuous real-time ambulatory urodynamic monitoring in infants and young children using infrared telemetry.

OBJECTIVE: To assess the feasibility of continuous real-time ambulatory bladder monitoring in infants and young children using a specially developed ambulatory urodynamic data logger with built-in infrared telemetric on-line facilities. PATIENTS AND METHODS: Twenty-nine infants and young children (mean age 3.9 years, range 7 weeks to 9.5 years) with various types of bladder dysfunction underwent urodynamic studies performed using an ambulatory urodynamic recorder with a specially developed integral transmitter that converts digital pressure signals to modulated infrared waves (935 nm). A receiver mounted on the ceiling of the room receives the signals emitted from the recorder. During the investigation, the infant can conduct normal activities, be totally mobile and be accompanied by the mother undisturbed in a private cubicle. The urodynamicist in the next room can observe all the patient's activities through a one-way mirror while continuous real-time on-line pressure signal displays are recorded and monitored using a computer, with event markers placed as necessary. For security, the data recorded during ambulatory investigation are stored in the internal memory of the ambulatory recorder. RESULTS: All 29 infants and young children completed the urodynamic studies using the new system; the results were satisfactory and reliable, with no data lost during ambulatory recording. The results obtained using infrared telemetry were not significantly different from conventional natural-filling urodynamic studies performed with a cabled on-line urodynamic recorder. CONCLUSION: The infrared telemetry system provides a reliable and effective way of performing continuous real-time ambulatory urodynamic monitoring in infants and young children. With the development of more powerful telemetric data transmission technologies, such a method could be extended in the near future to a truly ambulatory urodynamic recording with real-time on-line facilities, either at home or in the clinic, both for adults and for children.

Ambulatory Care↗

Implantable control, telemetry, and solar energy system in the moving actuator type total artificial heart.

The moving actuator type total artificial heart (TAH) developed in the Seoul National University has numerous design improvements based upon the digital signal processor (DSP). These improvements include the implantability of all electronics, an automatic control algorithm, and extension of the battery run-time in connection with an amorphous silicon solar system (SS). The implantable electronics consist of the motor drive, main processor, intelligent Li ion battery management (LIBM) based upon the DSP, telemetry system, and transcutaneous energy transmission (TET) system. Major changes in the implantable electronics include decreasing the temperature rise by over 21 degrees C on the motor drive, volume reduction (40 x 55 x 33 mm, 7 cell assembly) of the battery pack using a Li ion (3.6 V/cell, 900 mA.h), and improvement of the battery run-time (over 40 min) while providing the cardiac output (CO) of 5 L/min at 100 mm Hg afterload when the external battery for testing is connected with the SS (2.5 W, 192.192, 1 kg) for the external battery recharge or the partial TAH drive. The phase locked loop (PLL) based telemetry system was implemented to improve stability and the error correction DSP algorithm programmed to achieve high accuracy. A field focused light emitting diode (LED) was used to obtain low light scattering along the propagation path, similar to the optical property of the laser and miniature sized, mounted on the pancake type TET coils. The TET operating resonance frequency was self tuned in a range of 360 to 410 kHz to provide enough power even at high afterloads. An automatic cardiac output regulation algorithm was developed based on interventricular pressure analysis and carried out in several animal experiments successfully. All electronics have been evaluated in vitro and in vivo and prepared for implantation of the TAH. Substantial progress has been made in designing a completely implantable TAH at the preclinical stage.

Algorithms↗

A custom designed chip to control an implantable stimulator and telemetry system for control of paralyzed muscles.

A custom designed chip has been developed for the control of paralyzed muscles. The system is capable of fulfilling the stimulus and telemetry needs of advanced functional neuromuscular stimulation (FNS) applications requiring multiple channels of stimulation and multiple channels for sensor or biopotential sensing. An inductive radiofrequency link provides power to the implant device as well as 2 way transcutaneous communication. An application specific integrated circuit (ASIC) decodes the commands and provides functional control within the implant, and modular circuitry provides specific implant functions. The ASIC chip provides up to 32 independent channels of stimulation with independent control of stimulus pulse duration, pulse amplitude, interphase delay, recharge phase duration, and pulse interval. It can also control up to 8 independent back telemetry analog channels with independent control of sampling rate and pulse powering parameters (amplitude and duration). The mixed analog digital chip has been fabricated in 1.2 microm n-well CMOS technology.

Analog-Digital Conversion↗

[Experiences with telemetry-supported pacemaker controls in patients with VVI pacemakers].

Investigations on telemetry-supported pacemaker control were carried out in 55 patients with the VVI-pacemaker Quantum (Intermedics). The investigations were done at least once during the 6-24 month period after implantation. The telemetry function was utilised for pacemaker programming, for clarifying pacemaker defects and for characterising the type of pacemaker electrode used. It could be shown that the Osypka spiral electrode VY (Dr. Osypka) had a lower impedance, and greater pulse width and charge threshold in comparison with the two other electrodes used (Encor, Cordis; Polyflex, Intermedics). In 38 of the 55 patients (69%) a pulse amplitude of 2.7 V could be chosen, whereas an amplitude of 5.4 V was programmed in the rest. Pacemaker sensing threshold was set to values between 2.4 and 3.0 mV. Pacemaker problems appeared in three patients; in one patient due to programming too economically and in the other two due to pacemaker defects.

Adult↗

A wireless telemetry system for training users of upper limb prostheses.

Telemetry from prosthetic systems is useful in aiding the users and clinical team in setting up and training and monitoring in the use of a prosthesis. The different forms are discussed and a new radio frequency based telemetry system is described. This system uses a computer to display the data and a video mixer to place the information on the same screen as the image of the user so that their actions and control signals can be simultaneously recorded for later study.

Amputation, Surgical↗