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PubMed1980

Surgical aspects of temporal lobe epilepsy. Results and problems.

The Montreal Neurological Institute's experience with cortical resection for medically refractory temporal lobe epilepsy had grown to 1,102 patients as of the end of 1978, 932 in the non-tumoral category and 170 patients with tumors, including a few major vascular malformations. Follow-up data, (complete to date or to the patients' death in over 80% of the patients) shows that 70% of those with 2 or more years of adequate follow-up data (median period 11 years) have experienced a complete or nearly complete reduction of the seizure tendency. Since the attack pattern frequently does not give evidence as to the lateralization of the epileptogenic area, special EEG techniques are often required to select those patients apt to benefit from temporal lobectomy. Sphenoidal recordings with chronically implanted fine wire electrodes have been particularly useful. Telemetry has enhanced the capability of recording a large number of epileptic spikes during sleep and various daytime activities and of recording spontaneous attacks. An automatic spike detection gadget gives promise of major help in analyzing these lengthy records. The addition of a video tape system, correlated with the EEG telemetry system, aids in determining the side of origin of the seizures. A small number of patients in whom this could not be determined with these various EEG techniques, were studied with stereotactically implanted chronic depth electrodes employing a modification of the Talairach-Bancaud technique. Over 3/4 of these patients were shown to have the onset of their seizures to be sufficiently well lateralized to warrant temporal lobectomy.

Adolescent↗

PubMed1990

[Radiotelemetric studies of the body temperature of white-tufted monkeys (Callithrix jacchus)].

A newly developed telemetry system was used to study deep body temperature (BT) of two adult male common marmosets (Callithrix jacchus). The BT-curves of both monkeys showed a similar clear circadian rhythm with a range up to 3.5 degrees C. At environmental temperature of 28 degrees C (ET) the BT of the monkeys varied in the daytime dependent on their spontaneous activity, with little individual differences between 37.5 degrees C and 39.3 degrees C; at night the BT of the remarkably deeply-sleeping animals decreased to an average at 35.8 degrees C. Elevating ET up to 30 degrees C effected an increase of BT by 0.6 degrees C, both during day and night. On the contrary, reducing ET to 24 degrees C the BT increased only at night, by 0.2 degrees C at ad libitum food intake and 1.0 degrees C at fasting. Measurements of BT by inserted rectal thermometer caused, compared with telemetry, an average at 0.4 degrees C higher values.

Animals↗

PubMed2000

Radio-telemetric evidence of migration in the gregarious but not the solitary morph of the Mormon cricket (Anabrus simplex: Orthoptera: Tettigoniidae).

The Mormon cricket, Anabrus simplex, is one of just a few species of katydids (or bushcrickets, Orthoptera: Tettigoniidae) that, like migratory locusts, appear to have solitary and migratory morphs. Using radio telemetry we studied movements of individuals of two morphs of this flightless species. Individuals within each migratory band had similar rates of movements along similar directional headings whereas solitary individuals moved little and showed little evidence of directionality in movement. Our results also add to other recent radio-telemetry studies showing that flightless insects of 1-2 g in mass can be tracked successfully using these methods.

Animals↗

PubMed2001

Free-ranging heart rate, body temperature and energy metabolism in eastern grey kangaroos (Macropus giganteus) and red kangaroos (Macropus rufus) in the arid regions of South East Australia.

Eastern grey kangaroos (Macropus giganteus) are generally regarded as mesic inhabitants. Even though access to drinking water in permanent stock watering troughs is commonly available, these animals are still found in only low densities in arid pastoral areas. We hypothesised that the differential success of red and grey kangaroos in the arid zone may be due to higher energy requirements of M. giganteus with a concomitant need for increased food, rather than limitations imposed by inadequate water access. We set out to test this by indirectly measuring energy expenditure through the monitoring of heart rate by radio telemetry in semi-free-ranging eastern grey and red kangaroos (Macropus rufus). Radio telemetry measurements of heart rate were calibrated against oxygen consumption and were used in the assessment of energy expenditure of animals maintained in an 8-ha enclosure in the arid zone of southeast Australia. Heart rate provided a reliable estimate of oxygen consumption. This well-correlated relationship was curvilinear and was established for each individual. Behavioural observations revealed that both kangaroo species spent most of the day in low energy demanding activities. M. rufus were more active at night whilst M. giganteus were more active in the early mornings and late afternoons. Like other marsupials, both species had low field metabolic rates (FMRs). However, M. giganteus in keeping with their mesic history had higher FMRs than the more arid-adapted M. rufus, particularly during water restriction. Body temperature telemeters revealed a further species difference in that under hot conditions when water is freely available, M. rufus exhibits a higher and more labile daytime body temperature than M. giganteus. During the hottest part of the day M. giganteus maintain body temperature, relying upon increased evaporative cooling mechanisms, such as licking. Indeed, only when access to drinking water was restricted was thermolability evident in M. giganteus. Differences in behaviour and concomitant energy expenditure may thus contribute substantially to the divergent distribution and abundance of these two kangaroo species.

Adaptation, Physiological↗

PubMed1984

Value of radiotelemetry in a community hospital.

The use of radiotelemetry for continuous electrocardiographic monitoring of patients outside of special care units, although common practice in many community hospitals, has not been adequately studied. Two-hundred five consecutive patients placed on telemetry over a 3-month period were prospectively studied to determine the benefits of radiotelemetry. Fourteen episodes of significant arrhythmias in 12 patients who required specific intervention were detected over 608 patient-days of monitoring. Significant arrhythmias occurred only in patients with known or suspected coronary artery disease or in those with previously documented arrhythmias. Radiotelemetry in a community hospital, when available at a moderate daily fee and observed by trained personnel, appears to be a cost-effective and safe method of monitoring patients at moderate risk for life-threatening arrhythmias. Although the overall cost of the system appears justifiable because of better utilization of special care unit beds and the seriousness of the arrhythmias detected, there is no evidence showing an increase in either in-hospital or postdischarge survival in monitored patients. Any potential benefit is probably restricted to patients with definite or suspected coronary artery disease or previously documented arrhythmias. Telemetry in a community hospital can provide a valuable alternative to special care unit monitoring in selected cases, but its value in the assessment of syncope and palpitations in the absence of high clinical suspicion of arrhythmia is limited.

Arrhythmias, Cardiac↗

PubMed1989

Early hospital discharge after percutaneous transluminal coronary angioplasty.

To determine the safety and efficacy of early hospital discharge after percutaneous transluminal coronary angioplasty (PTCA), 100 patients were studied prospectively. A telemetry observation unit was established to monitor patients having uncomplicated procedures. A total of 170 lesions were dilated, with a procedural success rate of 96% and a clinical success rate of 91%. There were no deaths or patients who required emergency bypass surgery. Four patients developed abrupt vessel closure in the catheterization laboratory. No major complications developed in the telemetry observation unit or after discharge. Patients with high-risk lesion morphology, based on the American College of Cardiology/American Heart Association Task Force guidelines, tended to have a lower success rate and more procedural complications. Coronary dissections were angiographically detected in 33 patients and stratified into 6 types. To reduce possible adverse sequelae, all patients with complex dissections were triaged in the catheterization laboratory to an in-patient monitored unit for additional management. Accordingly, 20 patients were admitted to an in-patient unit for extended observation. Excluding 4 patients with myocardial infarction, 75% (12 of 16) were discharged the next day. Initial experience with early discharge suggests that under proper conditions the procedure is safe and effective. Patients with complex coronary dissections who are at high risk for abrupt vessel closure can be promptly identified after dilatation and triaged to an appropriate monitoring area. Early discharge after PTCA offers more efficient use of hospital facilities and the opportunity to reduce hospital costs.

Angioplasty, Balloon, Coronary↗

PubMed1983

Improved telemetric EEG monitoring in epileptic patients.

A 20-channel EEG telemetry system provides EEG monitoring with standard EEG recording performance for use in epileptic patients. The EEG activities of 20 electrodes are separately amplified and transmitted employing PCM cable telemetry. A standard EEG apparatus is used, allowing montages to be freely selected and changed during recording.

Electroencephalography↗

PubMed2005

Heart rate and heart rate variability of healthy cats in home and hospital environments.

To investigate heart rate and its variability, a telemetry device was affixed to 16 healthy, young cats. Prior to inclusion in the study, cats were subject to echocardiographic examination. The heart rate (HR) when cats were restrained for echocardiography (HR(r)) was calculated from 4-5 consecutive RR intervals obtained from a simultaneously recorded electrocardiogram. Electrocardiographic data were then acquired by telemetry in a quiet room in the veterinary hospital (VTH) and later, in the owner's home (home). The ambulatory data were digitally sampled and the RR interval tachogram from a 4 min epoch subject to Fast Fourier Transform to yield measures of heart rate variability (HRV). Sinus arrhythmia was often observed in resting cats. Heart rates (bpm) expressed as mean (+/-SD) were: HRr: 187 (+/-25), HRVTH: 150 (+/-23), HR(home): 132 (+/-19); each of these rates was significantly different from the others. Significant differences in profiles of HRV suggested that sympathetic tone was higher (and parasympathetic tone lower) when cats were in the hospital.

Animals↗

PubMed2005

Long-term monitoring of pulmonary arterial pressure in conscious, unrestrained mice.

INTRODUCTION: The ability to genetically engineer specific gene 'knock-out' mice has provided a powerful tool for investigating the various mechanisms that contribute to the pathogenesis of pulmonary arterial hypertension (PAH). Yet, so far there have been no reports describing the measurement of pulmonary arterial pressure (PAP) in the conscious wild type mouse-an essential requirement for monitoring dynamic changes associated with the pathogenesis of PAH. Therefore, in this study we describe a new technique for long-term measurement of PAP in conscious unrestrained mice using telemetry. METHODS: In five male C57BL/6 mice (B.W. 25-30 g), the sensing catheter of a telemetric transmitter was inserted into the right ventricle and advanced into the pulmonary artery. The transmitter body was positioned either within the abdominal cavity or subcutaneously on the back. During recovery from surgery, mean PAP was recorded daily for 1 week. Subsequently, the PAP responses to acute hypoxia (8% O2 for 10 min) and L-NAME (50 mg/kg, s.c.) were tested in three mice. RESULTS: By 1-week post surgery, all mice had fully recovered from surgery and baseline MPAP was stable at 14.9+/-0.7 mm Hg. Additionally, the pulmonary vascular stimulants acute hypoxia and L-NAME provoked a 63% and 86% increase MPAP, respectively. DISCUSSION: In summary, this study has demonstrated the ability to accurately measure PAP by telemetry in conscious, unrestrained mice. One important application of this technique for future studies is the possibility to assess the relative contribution of specific genes (using 'knock-out' mice) during the chronic development of pulmonary pathological conditions.

Animals↗

PubMed2004

Risk of aspiration pneumonia after an epileptic seizure: a retrospective analysis of 1634 adult patients.

We reviewed the incidence of aspiration pneumonia secondary to seizures in three populations of patients with chronic epilepsy: 733 outpatients seen in an Epilepsy Foundation clinic; 806 adult patients admitted to two university video telemetry units; and 95 institutionalized, profoundly retarded adult patients with chronic epilepsy. Two of the 733 adults who had seizures in the outpatient setting and 2 of the 806 patients who had one or more epileptic seizures in the telemetry units developed aspiration pneumonia. In the 95 institutionalized patients, there were 17 instances of aspiration pneumonia after a generalized seizure and 32 instances of aspiration unrelated to seizures over a 12-month period. Our findings suggest that aspiration pneumonia is not a common complication of seizures in otherwise healthy adults. The increased incidence of aspiration in developmentally delayed individuals seems to derive from a combination of factors. Increased oral secretions, impaired swallowing mechanisms, and difficulty in attaining adequate patient positioning significantly increased the risk of aspiration.

Adult↗

PubMed2003

Prulifloxacin: in vitro (HERG current) and in vivo (conscious dog) assessment of cardiac risk.

Prulifloxacin, a new thiazeto-quinoline derivative with antibiotic properties, was evaluated for cardiac risk both in vitro on the ether-à-go-go-related gene (HERG) K+ channel, and in vivo in the conscious dog monitored by telemetry. HERG current was measured from stably transfected human embryonic kidney (HEK) 293 cells by means of the patch-clamp technique. Application of AF 3013, the active metabolite of prulifloxacin, produced only minor reduction of HERG current amplitude (tail current=-40 mV), producing a maximum blockade of 12.3 +/- 3.3% at the highest concentration tested (335 microM). In comparison, ciprofloxacin also failed to produce a 50% inhibition of HERG current amplitude, although the maximum blockade was greater than that observed with prulifloxacin (47.6 +/- 1.9% at the highest concentration tested (335 microM). In contrast, moxifloxacin blocked HERG current amplitude with an IC50 value of 74.7 microM. Prulifloxacin had no effect on the QTc interval (Fridericia's) following 5 days of repeated oral administration (150 mg/kg/day) in the conscious dog monitored by telemetry. These findings suggest that prulifloxacin is not likely to prolong the QT interval.

Administration, Oral↗

PubMed1979

Unusual artifacts in electrocardiographic monitoring.

Three unusual artifacts noted during Holter and telemetry monitoring, not previously described, are presented. Recognition of the artifacts prevented misinterpretation and wrong treatment. The clues to the identification of the artifacts and the need for avoiding wrong interpretation and inappropriate treatment are discussed. The cause of the telemetry artifact is discussed.

Adult↗

PubMed2002

Age-related changes in sleep-wake rhythm in dog.

To investigate a sleep-wake rhythm in aged dogs, a radio-telemetry monitoring was carried out for 24 h. Electrodes and telemetry device were surgically implanted in four aged dogs (16-18 years old) and four young dogs (3-4 years old). Electroencephalogram (EEG), electromyogram (EMG) and electrocardiogram (ECG) were recorded simultaneously as parameters to determine vigilance states and an autonomic nervous function. Wakefulness, slow wave sleep (SWS) and paradoxical sleep (PS) were identified according to the EEG and EMG pattern. We also examined whether absolute powers and the low frequency-to-high frequency ratio (LF/HF) derived from the heart rate variability power spectrum could detect shifts in autonomic balance correlated with aging. The aged dogs showed a marked reduction of PS and a fragmentation of wakefulness in the daytime and a sleep disruption in the night. The pattern of 24 h sleep and waking was dramatically altered in the aged dog. It was characterized by an increase in the total amount of time spent in SWS during the daytime followed by an increasing of time spent in wakefulness during the night. Furthermore, LF/HF ratio showed a very low amplitude of variance throughout the day in the aged dog. These results suggest that the aged dog is a useful model to investigate sleep disorders in human such as daytime drowsiness, difficulties in sleep maintenance. The abnormality in sleep-wake cycle might be reflected by the altered autonomic balance in the aged dogs.

Aging↗

PubMed1990

The diagnostic impact of prehospital 12-lead electrocardiography.

STUDY HYPOTHESIS: It is feasible to apply prehospital 12-lead electrocardiography to most stable prehospital chest pain patients. Prehospital diagnostic accuracy is improved compared with single-lead telemetry. POPULATION: One-hundred sixty-six stable adult patients who sought paramedic evaluation for a chief complaint of nontraumatic chest pain. METHODS: One-hundred fifty-one prehospital 12-lead ECGs of diagnostic quality were obtained by paramedics on 166 adult patients presenting with nontraumatic chest pain. Paramedics and base station physicians were blinded to the information on acquired prehospital 12-lead ECGs and treated patients according to current standard of care-clinical diagnosis and single-lead telemetry. Final hospital diagnoses were classified into three groups: acute myocardial infarction (24); suspected angina or ischemia (61); and nonischemic chest pain (66). Paramedics and base station physicians' clinical diagnoses and prehospital and emergency department ECGs were similarly classified and compared. Prehospital and ED 12-lead ECGs were read retrospectively by two cardiologists. RESULTS: Paramedics achieved a high success rate (98.7%) in obtaining diagnostic quality prehospital 12-lead ECGs in 94.6% of eligible prehospital patients. For patients with acute myocardial infarction, prehospital ECG alone had significantly higher specificity than did the paramedic clinical diagnosis (99.2% vs 70.9%; P less than .001), and significantly higher positive predictive value (92.9% vs 32.7%; P less than .001). For patients with angina, combining the paramedic clinical diagnosis and the prehospital ECG significantly improved sensitivity (90.2% vs 62.3%; P less than .001) and increased negative predictive value (88.9% vs 71.3%; P less than .02) compared with paramedic clinical diagnosis alone. There was a high concordance between prehospital and ED ECG diagnosis (99.3% for acute myocardial infarction and 92.8% for angina). Furthermore, ten patients whose prehospital ECGs demonstrated ischemia and who had final hospital diagnoses of angina or acute myocardial infarction were mistriaged by paramedics and/or received no base station physician-directed therapy. CONCLUSION: It is feasible to apply prehospital 12-lead electrocardiography to most stable prehospital chest pain patients. Prehospital 12-lead ECGs have the potential to significantly increase the diagnostic accuracy in chest pain patients, approach congruity with ED 12-lead ECG diagnoses, and may allow for consideration of altering and improving prehospital and hospital-based management in this patient population.

Aged↗

PubMed1989

Evaluation of patients for the need of thrombolytic therapy in the prehospital setting.

Maximum benefit from thrombolytic therapy in acute myocardial infarction is obtained with early therapy. The earliest possible time to treat is during the initial evaluation of the patient in the home or ambulance, which requires accurate diagnosis of acute myocardial infarction in the prehospital setting. In our study, paramedics evaluated patients who had chest pain with a 12-lead ECG transmitted by cellular telephone and a checklist for inclusion and exclusion criteria for thrombolytic therapy. This information was transmitted to a hospital-based telemetry physician who diagnosed or excluded acute myocardial infarction and made a mock decision to withhold or administer a thrombolytic agent. Forty-eight patients with chest pain were evaluated. Six were diagnosed as having overt acute myocardial infarction by the hospital-based telemetry physician. All six patients had the diagnosis substantiated by both ECG and enzyme studies on hospital admission. Based on the data supplied by paramedics, two of these six patients were considered eligible for thrombolytic therapy by the physician. Hospital evaluation confirmed the prehospital decision to treat with a thrombolytic agent. In addition, all other patients were appropriately diagnosed as ineligible. Prehospital ECG diagnosis resulted in two patients going directly to the catheterization lab, thereby bypassing the emergency department. Overt acute myocardial infarction can be accurately identified by a prehospital-acquired 12-lead ECG transmitted to a hospital-based physician. Our study demonstrates that in conjunction with specially trained paramedics, the hospital physician can decide whether to administer thrombolytic therapy to such patients in the prehospital setting.

Adult↗

PubMed1997

Tolerance to the hypothermic and hyperthermic effects of chlorpyrifos.

Hypothermia is a commonly reported thermoregulatory response in rodents acutely exposed to organophosphates (OP); however, our laboratory has recently found a delayed hyperthermic response following the initial hypothermia when exposed to the OP, chlorpyrifos. It is well known that rodents display tolerance to OP-induced hypothermia but little is known about tolerance to OP-induced hyperthermia. Twenty female rats of the Long-Evans strain were made tolerant to chlorpyrifos by administering 0 or 10 mg/g chlorpyrifos by gavage daily for four days. Core temperature (T[c]) and motor activity (MA) were monitored continuously by telemetry. Twenty-four hours after the fourth 10 mg/kg injection, the animals were administered a challenge dose of 25 mg/kg chlorpyrifos or corn oil while the telemetry data were monitored for the next 72 h. Non-tolerant rats displayed an initial hypothermic response with reduced MA followed by a delayed increase in T(c) 24 h after exposure. The tolerant animals displayed a blunted hypothermic response with virtually no change in MA, but a delayed increase in T(c) similar to that of non-tolerant animals. The hyperthermic response of the non-tolerant animals persisted for two days, whereas the tolerant animals recovered by the second day. The data indicate that tolerance to the hypothermic and hyperthermic effects of chlorpyrifos involve separate neurochemical pathways.

Administration, Oral↗

PubMed2003

Telemetric animal model to evaluate visceral pain in the freely moving rat.

Several research groups have measured the visceromotor response to visceral distension by electromyography (EMG) in the conscious restraint, wrapped or lightly anaesthetized rat. Our aim was to develop a more physiological and stress-free technique that enables the simultaneous measurement of duodenal distension-induced visceromotor and cardiovascular responses in the conscious, freely moving rat. A telemetry transmitter, consisting of a bipolar electrode pair and arterial catheter, was chronically implanted into the rat to measure abdominal EMG, mean arterial pressure (MAP) and heart rate (HR). Furthermore, a balloon catheter was chronically implanted in the duodenum to deliver volume-fixed staircase (0.1-0.6 ml) or phasic (0.1, 0.3, 0.5 ml) distensions. The area under the curve (AUC; mVs) and maximal amplitude (EMG(max); mV) during distension were analyzed. The model was validated by pre-treatment with morphine (0.3, 1.5 and 3 mg/kg, intraperitoneally). Staircase and phasic distension produced a volume-dependent increase in AUC and EMG(max), HR and MAP. Pre-treatment with morphine inhibited the distension-induced visceromotor response, i.e. abdominal contractions, increase in AUC and EMG(max). These findings indicate that telemetry is an adequate tool to measure visceromotor and cardiovascular responses to averse, noxious duodenal distension continuously and simultaneously in the rats home cage, without additional handling-related or restraint-induced stress. The presented animal visceral model is intended for studying acute and chronic analgesic properties of new pharmaceutical compounds.

Analgesics, Opioid↗

PubMed2002

The effects of beta-endorphin (beta-END) on cardiovascular and behavioral dynamics in conscious rats.

Beta-endorphin (beta-END) a product of the proopiomelanocortin (POMC) has been demonstrated to play a role in the regulation of metabolic and autonomic responses. Recent studies have suggested the involvement of the endogenous opioid system in cardiovascular control. Previous studies conducted in our laboratory using anesthetized animals investigated the actions of beta-END and other POMC derived peptides on sympathetic and cardiovascular dynamics. In this study, we determined both the acute and chronic effects of beta-END on cardiovascular and behavioral dynamics in conscious unrestrained rats using radio-telemetry. Animals were instrumented with a radio-telemetry transmitter in the abdominal cavity and the attached catheter inserted into the femoral artery for recording of cardiovascular dynamics and activity. They were subsequently implanted with intracerebroventricular (ICV) cannulas. The acute ICV administration of beta-END significantly increased the mean arterial pressure (MAP) and heart rate (HR) compared to controls. The cardiovascular responses returned toward control levels after 2 h. In contrast, the chronic infusion of beta-END significantly decreased the MAP and HR during both the active and inactive phase. Chronic beta-END administration also decreased physical activity. Food intake was increased initially and later declined and water consumption followed a similar pattern. We conclude that in the conscious unrestrained animal the acute administration of beta-END increases MAP and HR while the chronic infusion of beta-END decreases MAP, HR, physical activity, and stimulate a short-term increase in food and water intake.

Animals↗