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At least 325 records · Page 18Linked to original sources

PubMed1995

Telemetry monitoring of hemodynamic effects induced over time by adenosine agonists in spontaneously hypertensive rats.

Using the telemetry system in spontaneously hypertensive rats (SHR), we evaluated the hemodynamic effects of four adenosine analogs having different selectivity for A1 and A2a adenosine receptor subtypes. The selective A2a agonists, 2-hexynyl-5'-N-ethylcarboxamidoadenosine (2HE-NECA) and 2-[4-(2-carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamidoaden osi ne (CGS 21680), the selective A1 agonist, 2-chloro-N6-cyclopentyl-adenosine (CCPA) and the nonselective agonist, 5'-N-ethyl-carboxamidoadenosine (NECA), were administered i.p. to conscious spontaneously hypertensive rats. For comparison, the calcium channel blocker, felodipine, was included. CCPA and 2HE-NECA were tested also by the oral route. Systolic and diastolic blood pressure and heart rate were recorded every 5 min for 24 hr after drug administration. Data were analyzed using the curve fitting model recently elaborated. All compounds caused dose-dependent antihypertensive effects. The i.p. dose inducing a decrease of 50 mm Hg (ED50) was calculated for both systolic and diastolic blood pressure. As regards diastolic blood pressure, ED50 values were: CCPA, 0.019 (0.013-0.027) mg/kg, 2HE-NECA, 0.009 (0.002-0.03) mg/kg, CGS 21680, 0.155 (0.084-0.246) mg/kg, NECA, 0.008 (0.004-0.016) mg/kg and felodipine, 5.16 (4.18-7.18) mg/kg. At equiactive doses, the antihypertensive effects of adenosine agonists were shorter lasting [t1/2 for DBP were: CCPA, 54 (44-76) min, 2HE-NECA, 57 (46-71) min, CGS 21680, 45 (21-94) min, NECA, 61(38-97) min] than those of felodipine [t1/2 = 233 (182-274) min]. After oral administration (0.3, 1 and 3 mg/kg), hypotension induced by 2HE-NECA was longer lasting than that of CCPA. 2HE-NECA, CGS 21680 and felodipine caused tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗

PubMed1995

The use of telemetry to record electrocardiogram and heart rate in freely swimming rats.

Measurement of parameters from the circulatory system of laboratory animals can play an important role in pharmacological or toxicological research. To study the mutual interaction between physical exercise and antioxidant systems in rats, we selected swimming as a model for exercise performance. Swimming belongs to the natural behavior of the rat, and under proper experimental conditions, it primarily involves physical exercise with little emotional arousal. Therefore, we developed a swimming basin in which the intensity of exercise could be manipulated through speed and duration of swimming. A laser beam interruption system enables the rat to be followed during each swimming session. A motor-controlled following device, consisting of a rail and sledge connected to a position sensor, contains an antenna mounted in a receiver board. In this way, we can record the electrocardiogram (ECG) and heart rate (HR) with a commercially available telemetry transmitter implanted in the peritoneal cavity of freely swimming rats and evaluate the physical fitness (condition) of the swim-trained rats.

Animals↗

PubMed1994

Robust estimates of wildlife location using telemetry data.

The location of wildlife is frequently determined using telemetry data gathered at short intervals. If radio transmissions are reflected, as often occurs in mountainous regions, then existing location estimation techniques re unreliable. We explore the effects of gross observation errors upon current analyses and suggest an alternative analysis based on robust state-space time-series modeling. We determine location estimates and their precisions, both for simulated and real mule-deer data, using current and robust procedures. Implementation and specification of filter parameters are also discussed. We conclude that the proposed filter-smoother is similar to the Gaussian filter-smoother when data are not greatly contaminated and that the robust version improves upon location estimates when contamination is large.

Animal Identification Systems↗

PubMed1977

Radio telemetry of intraocular pressure in vitro.

A guard ring pressure transensor, using the principles of surface applanation, was used to transmit intraocular pressure (IOP) from a cadaver canine eye. The transensor consisted of a passive resonant coil/capacitor combination, made pressure sensitive by the movement of a small ferrite plate which acted as its applanating surface. Oscillation induced in the transensor by a remote grid dip oscillator (GDO) was monitored by a digital frequency counter (DFC). The resonant frequency of oscillation in the transensor bore a linear relationship to the in vitro IOP in three separate experiments (coefficient of determination for linear regression, r2 equals 0.90). These data indicate that radio telemetry is feasible, using a miniature applanating passive radio telemetric device for continual monitoring of IOP.

Animals↗

PubMed1993

Step-down units and telemetry monitoring: optimizing utilization.

In this article, we address the issue of patient-flow problems in the hospital, which often occur because of improper utilization of step-down (intermediate care) unit resources. Utilization is often adversely affected by the inappropriate use of telemetry monitoring (traditionally offered in step-down units) as a rationale for placing patients in step-down areas, even when they would benefit from other types of monitoring or just the proper level of nursing care. We also discuss the other types of patient monitoring available, as well as other monitoring issues (see "Communicating Alarm Event").

Electrocardiography↗

PubMed1993

Oxygen consumption using the K2 telemetry system and a metabolic cart.

The purpose of this study was to compare measurements of oxygen consumption (VO2), ventilation (VE), and respiratory rate (RR) between a relatively new portable, telemetry system (K2) and a system that has been shown to be valid and reliable. Duplicate measurements were made at rest and during four levels of exercise in 10 subjects. Heart rate values were comparable for exercise at the same work level during gas collection using the two systems, indicating that the metabolic stresses were similar. Oxygen consumption measurements were significantly lower using the K2 system compared with a metabolic measurement cart (MMC). There was no significant difference in VE, but RR was lower for measurements made with the MMC. Compared with the MMC, the K2 system uses a slightly different formula to calculate VO2 because the content of carbon dioxide in expired air is not measured. To determine differences resulting from the method of calculating VO2, MMC measurements were applied to the formula used by the K2 system, and K2 values were adjusted using the RER values obtained from the MMC. There were no differences between these calculated values and the values obtained directly from either the MMC or the K2 system. Consequently, we concluded that the lower VO2 values obtained with the K2 system were attributed to the method of collecting and analyzing expired air, rather than to the method of calculating VO2.

Adult↗

PubMed1999

Estimating temporal independence of radio-telemetry data on animal activity

Radio-telemetry is an excellent tool for gathering data on the biology of animals and their interactions with the environment they inhabit. Many methods have been developed for analyses of spatial information, on home range size and utilization density. Activity patterns are often described using radio-tracking data, but no generally accepted method is currently available specifically for determining the temporal independence of this type of data for statistical inference. Activity rhythms have generally been analysed by ecologists with the assumption that data are temporally independent, or by subjectively fixing an independence interval, based on attributes of their ranging behaviour. Although some good approximations of activity patterns can be obtained in these ways, we underline the need for a functionally correct method of estimating independence interval. Here we use semi-variograms to estimate the minimum interval required for the readings to be sequentially independent. This geostatistical tool is applied to the analysis of data on activity of Chilean foxes (Pseudalopex culpaeus) and Chacoan peccaries (Catagonus wagneri). Data were collected in the field by radio-tracking over 24-hr periods, with readings on activity state taken every 15 min. The spatial dimension in which the theory of geostatistics lies has been transferred into the time dimension, so that the correlation interval is expressed in time units (min). Time of independence as estimated by the variogram was 110 min for foxes, while data on peccaries indicated that they have long periods of activity, more suitable for time-series analysis. Copyright 1999 Academic Press.

Journal Article↗

PubMed2000

Digital electromagnetic telemetry system for studying behaviour of decapod crustaceans.

1 year and the receiving system batteries are replaced by divers at intervals of up to 4 weeks. In field tests, crab (Cancer pagurus L.) and lobster (Homarus gammarus (L.)) activity was monitored at an artificial reef for 14 months. Examples of the type of information acquired are presented to illustrate the capabilities of the system and potential applications are discussed. Limitations of digital electromagnetic telemetry stem mainly from the short range of detection, the need for cables on the seabed and the size and shape of the transmitting tag.

Journal Article↗

PubMed1999

Development of an acoustic telemetry tag for monitoring electromyograms in free-swimming fish

We report the development of an acoustic telemetry tag used to monitor electromyograms (EMGs) remotely from free-swimming marine fish. The device described amplifies and filters the EMG and then converts the electrical waveform into a frequency-modulated acoustic signal that is transmitted through water. The signal is then received, demodulated and recorded by the receiving system. The EMG tag described has been tested on a range of species, including toadfish Opsanus &tgr;, spiny dogfish Squalus acanthias, yellowfin tuna Thunnus albacares and eastern Pacific bonito Sarda chiliensis, in different tank environments. In certain tanks the fidelity with which the system replicates the EMG is sufficient to quantify accurately the onset, offset, duration, the integrated area under the absolute value of the signal and the number of signal zero crossings. This EMG tag will expand the scope of questions that can be addressed about the behavior and physiology of free-swimming fish.

Journal Article↗

PubMed1996

Severe syncope due to the application of a pacemaker telemetry wand.

We report a case of a transient defective anodal contact between pacemaker ground plate and patient's tissues (the so-called dry pocket). During unipolar-DDD pacing, mild compression of the pocket with the telemetry head caused a severe syncope, due to asystole and secondary to complete loss of ventricular capture. Normal pacemaker function resumed with bipolar pacing configuration.

Equipment Failure↗

PubMed1997

Care and safety of pacemaker electrodes in intensive care and telemetry nursing units.

BACKGROUND: Temporary pacing leads with electrodes are a potential risk, because microshock inadvertently transmitted across the catheter or wire can paradoxically cause lethal dysrhythmias. Much attention has been paid to this complication in clinical guidelines, but little is known about actual practices used to protect patients. OBJECTIVES: A national survey was done to describe current practices related to the care of patients with temporary epicardial or transvenous pacing catheters. The survey focused on environmental factors that affect generation of static electricity, equipment used with temporary pacing, and nursing practices used when handling temporary pacing electrodes. METHODS: The Pacemaker Electrical Care and Safety Survey was developed, validated, and pilot tested before it was mailed to all 895 hospitals that perform cardiac surgery. Surveys were sent to the coronary care unit, cardiac surgical ICU, and telemetry units of each hospital. RESULTS: Responses were received from 476 units representing 388 (43%) of the 895 institutions. Most respondents reported using gloves, although few hospitals had policies mandating this practice. The insulating materials used most often, in order, were a glove or finger cot, tape, and gauze. Few units (25%) use any measure to reduce static electricity generated by movement over carpeting. Little attention was paid to insulating exposed epicardial temporary pacing electrodes at the generator. CONCLUSIONS: Temporary pacing electrodes were usually handled in an electrically safe manner; however, little attention was paid to environmental sources of microshock or connections between the generator and the cable. Although the respondents reported using a variety of insulating materials, the ideal cover for the exposed tips of the electrodes has not yet been determined.

Cardiac Pacing, Artificial↗

PubMed1964