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PubMedDate not supplied

Effects of a wireless local area network (LAN) system, a telemetry system, and electrosurgical devices on medical devices in a hospital environment.

Concerns have been raised about interference of wireless local area network (LAN) systems and telemetry systems with medical devices in hospitals. The authors have investigated the susceptibility of 65 electromedical devices to a wireless LAN system and a telemetry system in preselected areas of a hospital. Testing was based on the American National Standards Institute Standard C63.18. The wireless LAN system operated at 2.42 GHz with an output power of 100 mW. The telemetry system operated at 466 MHz with an output power of 4 mW. Of the 65 devices tested, only two hand-held Doppler units, a Mini Doppler Model D900 (Huntleigh Healthcare Ltd) and a Ultrasonic Doppler Model 811 (Parks Medical Electronics, Inc.), were affected by the LAN system. Placed within 10 cm of the LAN system in standby mode, both units emitted periodic high-pitched beating sounds, which could be misinterpreted as normal beating sounds from the patient. These changed to random static noise during data transmission by the LAN. Under normal conditions of use, a LAN system would never be placed this close to a medical device. The quality of data transmission from the LAN system changed from "good" to "acceptable" in the colonoscopy room. This deterioration in transmission quality could have been caused by the lead shielding in the room. Electrosurgical devices operating at 0.5 to 1 MHz did not affect the LAN system at distances up to 3 m. None of the devices was affected by the telemetry system. These findings suggest that wireless LAN systems and telemetry systems can be acceptable for use in hospitals. Nevertheless, other systems should be tested on potentially susceptible devices by the hospital before use.

Artifacts↗
PubMed2002

Medical telemetry is on the move. Is it time for you to change frequencies?

Medical telemetry in the United States is in the midst of a transformation. The VHF and UHF transmission bands traditionally used for most medical telemetry have become increasingly crowded. In response, the U.S. Federal Communications Commission (FCC) is making new frequency bands available exclusively for medical telemetry. Many users of the traditional bands will need to migrate out of them--but how soon will this become necessary? And what's involved in making the switch? In our September 2000 article "New Frequencies for Medical Telemetry: FCC's Plan Is Final--Now What?" we discussed some of the changes affecting telemetry. In the article that follows, we review those changes and explain what your facility needs to do in response.

Humans↗
PubMed1982

Biomedical telemetry techniques.

The landmarks and important state-of-the-art work in biomedical telemetry are reviewed. The advantages provided by transmission of physiologic data from minimally restrained to completely unencumbered subjects with biomedical telemetry systems is discussed both from the standpoint of the wide variety of physiologic parameters and subjects that can be monitored and in terms of the various proven electronic techniques for implementing this mode of physiologic data transmission and recovery. Monitored parameter capabilities now include biopotentials (ECG, EMG, EEG), temperature, mechanical events (muscle force, limb motion), pH, pressure (ICP, blood pressure), and others. The system developments in biomedical telemetry have had the aims of minimizing size, weight, and volume while extending the operating capabilities of the systems in terms of minimum required power, multiplicity of data channels, and reliable operation in the intended operating environment. These developments have progressed from discrete transistor to integrated microcircuit implementations in systems which can encode the physiologic data as FM, PAM, PWM, or PCM. Biotelemeters can be utilized as external (backpack) or completely implantable devices and today may be found in the research laboratory, the intensive care unit, portable patient care units, and in the freely ranging animal in the field usually employing a radio link. Also discussed are considerations for power sources and power source recharging through the tissues of implanted subjects. There are advantages and disadvantages to using biomedical telemetry, to using implanted or external biotelemeters, and to each of the various encoding techniques. These are considered, and the future of biomedical telemetry is projected.

Animals↗
PubMed1994

The role of telemetry in perinatal monitoring.

In the field of transmission and exchange of clinical information particularly good results are foreseen with the development of data telemetry. In perinatal medicine the telemetric technologies are being employed in several situations. It is possible to subdivide the telemetric technologies into short and long distance systems. Short distance telemetry employs devices which utilize radiowaves or laser techniques to transmit data from the original source to centralized equipment; the main application is the transmission of the cardiotocographic signal to permit ambulation of the patient during recording. It may allow fetal heart rate testing to be performed in a setting more acceptable to patients telemetric not be physically confined to a bed or a chair. The telemetric transmission of the cardiotocogram (CTG) may solve problems of organization when the ratio of parturient to midwife exceeds 1:1. Long distance telemetry consists of the telephone transmission of data obtained from distant source to a consultation center where the data can be evaluated, stored and where hospital staff may suggest appropriate decision related to clinical course. In prenatal medicine, the system can offer the monitoring of maternal blood pressure, automatic urine and glucose analyses, surveillance of fetal heart rate and uterine contractions. CTG telemetry has been used with good results for the prevention of preterm labor while blood pressure control by telemetry may be useful for the prevention and management of gestational hypertension. Knowledge by the pregnant woman that it is possible to continuously monitor by telemetric technology her health and the health of her fetus provides reassurance during a delicate period.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1993

Use of telemetry to record electrocardiogram and heart rate in freely moving mice.

This paper describes for the first time the possibility to record the electrocardiogram (ECG) and heart rate (HR) with a commercially available telemetry and data acquisition system in freely moving mice. The system comprises a telemetry transmitter implanted in the peritoneal cavity and a receiver, placed underneath the home cage, an A/D converter (MacLab) and a Macintosh LC II 4/80 computer with software (MacLab, Chart/Scope). The raw analog ECG data are digitized within the MacLab and can be converted to HR data additionally. The effects of surgery for implanting the transmitter, handling and anesthesia by either Nembutal or a mixture of Hypnorm, Dormicum, and water, on the changes in ECG and HR were examined. The telemetry system for recording the ECG and HR provides an accurate and reliable method for monitoring the direct effects of handling on HR. By using this telemetry system, we maintain that measurements in freely moving animals are more efficient, reliable, and less labor-intensive than the measurement techniques described in the literature thus far.

Animals↗
PubMed2006

Methodological validation of an existing telemetry system for QT evaluation in conscious guinea pigs.

INTRODUCTION: Guinea pigs are suitable for in vivo QT assessment of newly discovered drugs at the pre-clinical stage because of the ease with which these animals can be handled, the lower amount of compound required for testing, and the similarity of the ion channels between the guinea pig heart and the human. Our purpose was to provide detailed methodological information on an existing telemetry recording system for use in evaluating QT interval prolongation in guinea pigs. METHODS: Hartley guinea pigs weighing 400-700 g were used to investigate the appropriate configuration of electrodes to record defined T-waves and the influence of the surgical implantation of a transmitter on the QT interval, as well as to determine the appropriate formula for QT correction. In addition, the validity of using telemetry-monitored guinea pigs was tested by using compounds with (positive references) or without (vehicles) a QT-prolonging effect. RESULTS: A lead with the negative pole placed between the scapulas and the positive pole positioned close to the sternum was found to be the most appropriate to obtain well-defined T-waves. The period for recovery from transmitter implantation was estimated to be at least 1 week. The best-fit formula for our telemetry guinea pig model was a modified Bazett's formula. QTc was prolonged significantly in guinea pigs given positive references, and the QTc was unaffected when the animals were given vehicles. DISCUSSION: We believe that the information provided herein will be a quite helpful guide for researchers to evaluate the QT interval reliably and reproducibly in this telemetry guinea pig model.

Animals↗
PubMed2000

Continuous telemetry from a chronic canine model of sudden cardiac death.

INTRODUCTION: We sought to develop a continuously telemetered animal model of sudden cardiac death (SCD) to study the role of existing infarcts and acute ischemia in fatal arrhythmias. METHODS AND RESULTS: A telemetry system capable of recording eight channels of electrophysiologic data continuously and chronically has been developed. To demonstrate the use of this technology in an animal model of sudden death, 12 anesthetized dogs were instrumented with eight electrodes located in endocardium of the right side of the heart, epicardium of the left ventricle (LV), or in the subcutaneous tissues. The left anterior descending (LAD) coronary artery was occluded for 90 minutes and reperfused to produce LV infarction. A copper wire was placed in the left circumflex (LCX) coronary artery to cause intimal injury in a second arterial bed. The telemetry unit recorded deaths in seven animals between 19 to 64 hours after surgery. Five animals that did not experience SCD by the fifth postoperative day served as controls. There were three modes of SCD: complex ventricular ectopy that degenerated into ventricular fibrillation (VF, n = 4); normal sinus rhythm that suddenly degenerated into VF (n = 1); and bradycardia (RR intervals >1,000 msec) that lasted >3 minutes and preceded VF (n = 2). ST segment changes were significantly greater in the LCX-bed electrograms for tachyarrhythmic compared to bradyarrhythmic deaths (mean +/- SD; 4.0 +/- 3.4 mV and 0.2 +/- 0.8 mV, respectively). Fast Fourier transform showed the peak frequency of VF 10 seconds after onset was significantly higher in the five dogs with initial tachyarrhythmias compared with the VF that followed profound bradycardia (6.5 +/- 3.1 Hz and 3.7 +/- 0.6 Hz, respectively). Computer-assisted planimetry of postmortem heart slices revealed that infarcts in the two dogs with bradycardic events were larger (19.7% +/- 2.2% of the LV and septal mass) than in the five dogs with tachyarrhythmias (7.7% +/- 2.4%) or in the five control dogs (11.9% +/- 8.1%). CONCLUSION: It is possible to record via telemetry the events leading to SCD in an animal model. Continuous telemetry monitoring demonstrated that both tachyarrhythmias and bradyarrhythmias ultimately resulted in VF in an animal model of SCD. Animals with tachyarrhythmic deaths had greate ischemia in the LCX bed, smaller preexisting infarcts, and higher VF peak frequency than animals with bradyarrhythmic deaths.

Animals↗
PubMed2005

Inpatient telemetry does not need to be used in the management of older patients hospitalized with chest pain at low risk for in-hospital coronary events and mortality.

BACKGROUND: Little is known about patients admitted with chest pain to inpatient telemetry units directly from an emergency department. METHODS: We analyzed data from 105 consecutive patients who presented with chest pain to an emergency department and who were hospitalized in an inpatient telemetry unit but who were at low risk for a coronary event. RESULTS: Telemetry yielded no information which was used to manage any patient. None of the 105 patients (0%) developed a myocardial infarction or died during hospitalization. At 4.8-year follow-up, 8 of 105 patients (8%) died. Significant risk factors for long-term mortality were age (p < .001), prior coronary artery disease (p < .05), and diabetes (p < .02). CONCLUSIONS: Inpatient telemetry was of no value in predicting short-term coronary events or mortality or long-term mortality in low-risk patients hospitalized with chest pain.

Age Factors↗
PubMed2002

Internal carotid-inferior petrosal sinus fistula complicating foramen ovale telemetry: successful treatment with detachable coils: case report and review.

OBJECTIVE AND IMPORTANCE: Iatrogenic internal carotid artery-cavernous sinus fistula complicating percutaneous foramen ovale (FO) instrumentation (e.g., retrogasserian rhizotomy for trigeminal neuralgia) has been reported in only four patients to date. To our knowledge, no case of fistula has previously been reported either to complicate FO telemetry or to involve the inferior petrosal sinus (IPS); moreover, most patients have presented within 48 hours. We present a case of internal carotid artery-IPS fistula that complicated FO telemetry in which the clinical syndrome was delayed by 4 weeks. CLINICAL PRESENTATION: Four weeks after undergoing bilateral FO telemetry during Phase 2 investigations for surgery for epilepsy, a 37-year-old man suddenly developed a painful bilateral pupil-sparing oculomotor palsy, poor visual acuity, proptosis, conjunctival suffusion, and an audible bruit over the right frontotemporal region. INTERVENTION: Cerebral angiography demonstrated a high-flow arteriovenous fistula between the junction of the petrous and laceral portions of the right internal carotid artery and right IPS, with rapid filling of both cavernous sinuses. Successful obliteration was obtained with Guglielmi detachable coils, followed by complete resolution of the bilateral ocular abnormality. CONCLUSION: This is the first reported case of iatrogenic fistula formation to either involve the IPS or to complicate FO telemetry. In addition, symptomatology was anomalously delayed. This case highlights the importance of noting FO anatomic asymmetries before FO instrumentation and of routinely inquiring for "swooshing" noises after electrode withdrawal.

Adult↗
PubMed2005

Neural response telemetry results with the nucleus 24 contour in a perimodiolar position.

OBJECTIVE: The purpose of the study was to analyze changes in neural response telemetry using the Cochlear Nucleus 24 Contour before and after stylet removal in a human model. STUDY DESIGN: Prospective study. SETTING: Tertiary referral center. PATIENTS: Twelve patients (23-72 years old) undergoing cochlear implantation, using the Nucleus 24 Contour implant, secondary to congenital and age-related hearing loss. INTERVENTION: Cochlear implantation with Cochlear Nucleus 24 Contour implant. MAIN OUTCOME MEASURE: Neural response telemetry thresholds were recorded initially with the stylet in and then with the stylet out during the implant procedure. RESULTS: Stimulus levels to obtain neural response telemetry threshold after stylet removal were statistically lower after the stylet was removed. CONCLUSION: The Nucleus 24 Contour achieves a perimodiolar position once the stylet is removed, and this leads to reduction in the current required to elicit a threshold neural response telemetry response.

Action Potentials↗
PubMed1993

Measurement of blood pressure and heart rate by telemetry in conscious, unrestrained marmosets.

A system is described for the continuous measurement of blood pressure, heart rate, and motor activity by telemetry in conscious marmosets freely moving in their home cages. Consistent diurnal variations in these parameters were observed under standard conditions, although these parameters were sensitive to changes in the environment. Blood pressure values were similar to those measured by nontelemetric methods in conscious, restrained marmosets. However, heart rate was lower, indicating that telemetry is less stressful. The suitability of this system for assessing the effects of blood pressure-lowering drugs was evaluated. An acute or a prolonged treatment with a converting enzyme inhibitor of marmosets maintained on a low-sodium diet induced a fall in blood pressure as previously observed using nontelemetric methods. With telemetry, however, more accurate information on the duration of response and the effects of the treatment on the diurnal rhythms was obtained. These observations demonstrate the advantages of telemetry for evaluating the hemodynamic effects of drug treatments under physiological conditions.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2005

QT PRODACT: sensitivity and specificity of the canine telemetry assay for detecting drug-induced QT interval prolongation.

The purpose of this investigation was to define the sensitivity and specificity of the canine telemetry assay for detecting drug-induced QT interval prolongation. Data from twelve studies generated in the QT PRODACT project were used in this investigation. The study design was a 4x4 Latin square cross-over design and included the following drugs: MK-499, E-4031, terfenadine, haloperidol, cisapride, bepridil, propranolol, diphenhydramine, captopril, verapamil, amoxicillin, and ciprofloxacin. The estimated root squared error of the model, which estimated the slope of the QT-RR relationships for each animal, for all dogs during the pre-dosing period was 5.45%. Using the QT-RR model, the sensitivity and specificity in each cutoff value that judges QT prolongation were estimated based on the experiment errors and measurement errors in the 12 studies. When the cutoff value was 5%, the sensitivity in 10% prolongation was 0.978 and the specificity in 0% was 0.996. In conclusion, it was judged that a 5% cutoff value for changes in heart rate corrected QT interval using the canine telemetry assay is practical, and the sensitivity and specificity of the telemetry assay are very high when using the analytical method presented here. Based upon this information, the canine telemetry assay using the individual subject heart rate correction model is recommended as a sensitive test system for the in vivo assessment of risk for QT interval prolongation.

Animals↗
PubMed2002

Is telemetry monitoring necessary in low-risk suspected acute chest pain syndromes?

BACKGROUND: Non-ICU telemetry monitoring has proven to be a valuable resource for patients suspected of having an acute myocardial infarction. While a significant number of patients are admitted to these units, the actual incidence of events or interventions is low. OBJECTIVE: To identify a subset of patients in whom telemetry monitoring does not alter management. DESIGN: Prospective observational study. SETTING: Large tertiary care facility. PATIENTS: A total of 414 patients consecutively admitted from the emergency department for suspected acute coronary syndromes were studied. Patients were excluded if they presented with ST-segment elevations, were revascularized on hospital admission, were admitted to a surgical service, were transferred from another floor or unit, or remained in the emergency department for the course of the stay. OUTCOMES: Events were defined as development of myocardial infarction, episodes of chest pain, new or rapid atrial arrhythmias, ventricular arrhythmias, any form of AV nodal block, and asystole. Intervention or change in management was any increase, decrease, or change in medication, cardioversion, electrophysiology study, or transfer to the ICU. RESULTS: Patients who had atypical chest pain and normal ECG findings were significantly less likely to have both intervention and events (4 interventions vs 23 interventions [p < 0.0001], 12 events vs 45 events [p < 0.0001]), compared to those with typical chest pain and abnormal ECG findings. When normal laboratory values were added, only four telemetry events were observed. CONCLUSION: Patients with atypical chest pain and normal ECG findings represent a subset of patients with low risk for life-threatening arrhythmia. Use of telemetry monitoring in this subset of patients should be reevaluated.

Acute Disease↗
PubMed1991

Centralized telemetry monitoring: implementation and management.

Baptist Memorial Hospital in Memphis, Tennessee has implemented a newly designed cardiac arrhythmia monitoring system. Management engineers worked closely with nurses and physicians in the design process which led to development and implementation of a centralized telemetry monitoring system. Changes in the work distribution, improvement of the work environment, efficient use of nursing personnel and upgrades of monitoring equipment are several of the objectives addressed by this new centralized monitoring system. The backbone of the centralized telemetry monitoring system is an effective communication system that fully addresses staff needs during emergency situations. This paper presents the communication system features as well as the operational, functional and technical considerations necessary to support a centralized telemetry monitoring system. Some topics covered in detail include communication system selection, staff scheduling, selection, training, and supervision of staff members, ergonomic workstation design parameters and centralized telemetry monitoring system benefits. One benefit observed was that an additional 35 minutes per nurse per shift was made available to provide additional patient care activities.

Arrhythmias, Cardiac↗
PubMed1979

A general-purpose implantable multichannel telemetry system for physiological research.

The majority of physiologically significant parameters can be accurately measured with relatively simple transducers and with a minimum of sophisticated electronics; such parameters include temperature, pressure, and electrical activity and generally require less than a 200 Hz bandwidth. In most experiments, however, measurements at multiple sites are needed to characterize fully a particular response, and the use of totally implantable telemetry systems becomes attractive as the problems of percutaneous leads in conscious animals are compounded in proportion to the number of sensors. These systems have been produced in limited quantities because a large number of components and long assembly times are necessary to provide simple amplifications and signal processing in a small implantable package. A new six-channel system incorporates all signal processing on a single integrated circuit, and only one CMOS divider chain and an integrated telemetry transmitter are required for support. This high level of integration accelerates assembly time and increases reliability by minimizing the interconnections. Such advancements are essential before the full potential of implantable telemetry can be realized. This paper details the performance of this system during initial applications requiring pressure, bioelectrical, or temperature telemetry.

Animals↗
PubMed1981

An implantable micropower command receiver for telemetry battery power switching.

Command receivers that control the functioning of additional implanted circuitry can be useful in many medical telemetry applications. The authors have designed and constructed a thick-film hybrid command receiver system that directly interfaces with the second-generation ICP telemetry system. This command receiver controls telemetry on/off state through enabling/disabling the telemetry pulse generator stage. Lithium battery powering of the implant is made practical through use of this command receiver. An automatic power shutdown feature is incorporated to guard against accidental battery drain. The unit uses two commercial CMOS integrated circuits, a transistor, a resistor and an RF coil.

Electric Power Supplies↗
PubMed1976

Telemetry in health care.

This article reviews the use of telemetry in health care. Monitoring of biological signals of medical importance such as the EKG, EEG, and EOG are described. Employment of telemetry in critical medical and surgical environs such as the delivery and operating suites is covered. The enormous importance of telemetry compatible with public communication systems such as voice grade telephone lines for remote medical care is discussed. The article does not enter into strictly engineering systems aspects in any detail; this was not the intent of the author. Nor is there any pretence to a completeness obviously not possible within its confines. It does concentrate on radio (wireless) telemetry transmissions over relatively great distances with freedom of patient movement.

Cardiac Output↗
PubMed1998

Telemetry system for monitoring anterior cruciate ligament graft forces in vivo.

Quantifying changes in the tension of an anterior cruciate ligament (ACL) graft in vivo during rehabilitative exercises is useful for developing the optimum rehabilitation for patients who have had reconstructive surgery. The purpose of the work reported is to design, build and test a telemetry system that can measure the in vivo ACL graft tension post-operatively. A commercially available fixation device is modified to sense the graft tension, house electronic components, transmit an output signal and pass the power generating signal. A transcutaneous inductive link is used to power the implanted telemetry electronics. The current difference technique is used to measure changes in two resistance strain gauges that monitor shear strain developed on the femoral fixation device by the ACL graft. This current regulates a frequency-modulated output signal that is transmitted using a new technique. Harnessing the ionic and volume conduction properties of the body fluids, the new technique involves injecting current subcutaneously into the tissue and then sensing the potential developed on the skin by surface electrodes. The waveform shape, amount of charge injected, charge density and current density are regulated to avoid tissue damage, pain and unwanted muscular stimulation. A signal conditioning board detects and converts the output to an analogue voltage for collection by a computer data-acquisition system. A performance evaluation demonstrates that the telemetry system either meets or exceeds all of the criteria necessary for the application.

Anterior Cruciate Ligament↗