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At least 541 records · Page 30Linked to original sources
PubMed2005

Wireless multichannel biopotential recording using an integrated FM telemetry circuit.

This paper presents a four-channel telemetric microsystem featuring on-chip alternating current amplification, direct current baseline stabilization, clock generation, time-division multiplexing, and wireless frequency-modulation transmission of microvolt- and millivolt-range input biopotentials in the very high frequency band of 94-98 MHz over a distance of approximately 0.5 m. It consists of a 4.84-mm2 integrated circuit, fabricated using a 1.5-microm double-poly double-metal n-well standard complementary metal-oxide semiconductor process, interfaced with only three off-chip components on a custom-designed printed-circuit board that measures 1.7 x 1.2 x 0.16 cm3, and weighs 1.1 g including two miniature 1.5-V batteries. We characterize the microsystem performance, operating in a truly wireless fashion in single-channel and multichannel operation modes, via extensive benchtop and in vitro tests in saline utilizing two different micromachined neural recording microelectrodes, while dissipating approximately 2.2 mW from a 3-V power supply. Moreover, we demonstrate successful wireless in vivo recording of spontaneous neural activity at 96.2 MHz from the auditory cortex of an awake marmoset monkey at several transmission distances ranging from 10 to 50 cm with signal-to-noise ratios in the range of 8.4-9.5 dB.

Action Potentials↗
PubMed2003

Persistence and heterogeneity in habitat selection studies using radio telemetry.

Biologists attach radio transmitters to animals so that the animals' movements through their preferred habitats can be followed. To analyze the resulting sequences of visited habitat classes, McCracken, Manly, and Vander Heyden (1998, Journal of Agricultural, Biological, and Environmental Statistics 3(3), 268-279) proposed an independent multinomial selections (IMS) model. Two issues that arise when using this approach are: (i) serial dependence possibly affects measures of uncertainty; and (ii) individual animals from the population studied may exhibit heterogeneity in their selection patterns. We develop two single-parameter extensions of the IMS model to address these issues. A Markov chain model allows for persistence in the habitat class previously visited. Heterogeneity is modeled by assuming the population of animal selection patterns follows a Dirichlet distribution, from which the study animals are a random sample. We show that these persistence and heterogeneity characteristics are present in the study by McCracken et al. (1998) of bear movements. Simulations demonstrate that failure to account for persistence or heterogeneity when either is present can seriously misrepresent measures of uncertainty.

Animals↗
PubMed1976

ECG telemetry for pacemaker check-up.

Experience from 1 000 ECG transmissions by telephone for check-up of pacemaker patients is reported. The method and its indications are described. The quality of the ECG is usually good, but sometimes there are unsuccessful transmissions, and the technical problems are discussed. An adequate analysis of cardiac pacing function could always be made. Furthermore, valuable information of different types of arrhythmia was gained on several occasions.

Arrhythmias, Cardiac↗
PubMed1996

Measurement of oxygen consumption in disabled children by the Cosmed K2 portable telemetry system.

Measurement of the energy cost of walking in children with cerebral palsy or spina bifida is difficult due to the cumbersome nature of equipment used to assess oxygen consumption. Such information collected with a lightweight telemetric system, the Cosmed K2, correlated well with that from a non-portable breath-by-breath system associated with a treadmill. The K2 did not significantly affect regular gait pattern as measured by gait analysis, and repeatability was satisfactory. Measurement of the energy cost of walking in the individual is unreliable in detecting differences of less than 10%; comparison between groups is more useful.

Adolescent↗
PubMed1983

Falsely localizing ictal onsets with depth EEG telemetry during anticonvulsant withdrawal.

A patient with partial complex seizures evaluated for surgery with chronic depth electrode recordings demonstrated falsely localizing ictal onsets during anticonvulsant drug withdrawal. When phenytoin was being reduced, more seizures appeared to originate from the left temporal lobe than from the right. Right anterior temporal lobectomy, performed on the basis of other findings, revealed a small unsuspected tumor in the resected specimen, and the patient has remained seizure free for 3 years. The seizures that originated from the left temporal lobe were different from the patient's habitual attacks and appeared to be the result of anticonvulsant withdrawal and, perhaps, electrode irritation. Four other patients who received anterior temporal lobectomies at UCLA between 1977 and 1980 had at least one stereotaxic EEG (SEEG)-recorded contralateral seizure onset, and all have benefited from surgery. Although multifocal SEEG-recorded ictal onsets should be considered a poor prognostic sign, distant sites that give rise to atypical seizures during drug withdrawal may not generate spontaneous seizures postoperatively. Consequently, this finding should not be used as a sole criterion against the recommendation of surgical therapy.

Adult↗
PubMed1999

Time trends in the intracardiac potential recorded by pacemaker telemetry: comparison between steroid-eluting small area electrodes.

We assessed the time course of electrograms sensed both in the atrium and ventricle by two different steroid-eluting electrodes: Medtronic Capsure SP (with an area of 5.5 mm2) and Z (with an area of 1.2 mm2). We considered 68 unipolar electrodes: 31 atrial (19 Capsure SP 4523 and 12 Capsure Z 4533) and 37 ventricular (24 Capsure SP 4023 and 13 Capsure Z 4033) implanted in 47 consecutive patients (30 men and 17 women, with an age of 72 +/- 9.4 years). The pacemaker model was Medtronic Elite 7077-7086 (DDD-DDDR) in 25 patients and Medtronic Legend 8419-8424 (VVIR-AAIR) in 22 patients. The endocavitary signal (all patients had spontaneous rhythm) was telemetrically obtained by a Medtronic 9790 device and acquired on a personal computer at implantation and 7, 30, and 180 days thereafter. The signal was studied both in the time domain and in the frequency domain by spectral analysis. The following parameters were calculated: amplitude (A): peak-to-peak value of the complex; slew rate (SR) peak negative first derivative; F0: frequency at which the power spectrum reaches its maximum value; and bandwidth (Bw): expressed as the distance between the -3 dB points and statistically analyzed by a two-way analysis of variance with factors "time" (four measurements) and "electrode" (Capsure SP and Z) and repeated measurements on the former. Ventricular sensing: no time or electrode effect (P > 0.1 in all comparisons) was found for F0, Bw, or SR, while a time effect (P < 0.04) not dependent on the type of electrode was found for the amplitude of the signal. In particular, a significant increase was found between the measurement at 6 months and that at implantation (P < 0.004). Atrial sensing: A, F0, and bandwidth were not affected by time or electrode (P > 0.09), while SR behaved differently over time (P < 0.05) in the two electrodes (the Capsure Z showed an increase at sixth month [P < 0.04] compared to implantation). In conclusion, the Medtronic Capsure SP and Z electrodes proved to be valid and substantially equivalent as far as concerns the measurement of the intracardiac potential despite the difference between their surface areas. Further studies should be devised to assess whether transitory decreases of atrial Bw in the first month of follow-up observed in a few patients for both electrodes could be responsible for clinical episodes of sensing deficit.

Aged↗