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PubMed1998

Development of an analysis system for 24-hour blood pressure and heart rate variability in the rat.

We have developed a system to evaluate 24-h changes of heart rate (HR) and blood pressure variability (BPV) in free moving rat. As a sensor to monitor electrocardiogram, we used the telemetry system. Analog data were sent to an analog to digital converter directly. The data were digitized at a sampling frequency of 1250 Hz and digitally stored on a computer. RR-intervals (difference of successive RR in electrocardiogram) were calculated using custom designed programs. Circadian change of the blood pressure and heart rate variability were calculated. We suggest that the system is a powerful tool in the evaluation of circadian changes of hemodynamics and autonomic nervous function in free moving rats.

Algorithms↗

PubMed2005

Nursing time allocation and other considerations for staffing.

The purpose of this project was to evaluate how nursing staff on the telemetry unit at Merle West Medical Center, a rural Pacific northwest community medical center in the USA, spend their time on selected nursing tasks, and how they believed staffing and patient acuity levels could best be determined. A self-report survey tool was developed, piloted and administered. Of the tasks that were listed in the survey, registered nurses (RNs) reported spending 39% of their time performing tasks that RNs only can perform. RNs reported spending 12% of their time performing activities that certified nursing assistants (CNAs) could perform alone and 49% of their time was spent on tasks that both RNs and CNAs must perform. Results from the quantitative portion of the survey indicated that RNs may not be used efficiently due to task overlap. Administering a modified survey which includes a balance of direct and indirect patient care tasks, as well as only those tasks that are truly performed frequently, will increase the relevance of the results.

Activities of Daily Living↗

PubMed2005

Changes in cutaneous and body temperature during and after conditioned fear to context in the rat.

Infrared thermography was used to image changes in cutaneous temperature during a conditioned fear response to context. Changes in heart rate, arterial pressure, activity and body (i.p.) temperature were recorded at the same time by radio-telemetry, in addition to freezing immobility. A marked drop in tail and paws temperature (-5.3 and -7.5 degrees C, respectively, down to room temperature), which lasted for the entire duration of the response (30 min), was observed in fear-conditioned rats. In sham-conditioned rats, the drop was on average half the magnitude and duration. In contrast, temperature of the eye, head and back increased (between + 0.8 and + 1.5 degrees C), with no difference between the two groups of rats. There was a similar increase in body temperature although it was slightly higher and delayed in the fear-conditioned animals. Finally, ending of the fear response was associated with a gradual decrease in body temperature and a rebound increase in the temperature of the tail (+ 3.3 degrees C above baseline). This study shows that fear, and to some extent arousal, evokes a strong cutaneous vasoconstriction that is restricted to the tail and paws. This regionally specific reduction in blood flow may be part of a preparatory response to a possible fight and flight to reduce blood loss in the most exposed parts of the rat's body in case of injury. The data also show that the tail is the main part of the body used for dissipating internal heat accumulated during fear once the animal has returned to a safe environment.

Animals↗

PubMed2005

Fibre-type composition of rabbit jaw muscles is related to their daily activity.

Skeletal muscles contain a mixture of fibres with different contractile properties, such as maximum force, contraction velocity and fatigability. Muscles adapt to altered functional demands, for example, by changing their fibre-type composition. This fibre-type composition can be changed by the frequency, duration and presumably the intensity of activation. The aim of this study was to analyse the relationship between the spontaneous daily muscle activation and fibre-type composition in rabbit jaw muscles. Using radio-telemetry combined with electromyography, the daily activity of five jaw muscles was characterized in terms of the total duration of muscle activity (duty time) and the number of activity bursts. Fibre-type composition of the muscles was classified by analysing the myosin heavy chain content of the fibres. The amount of slow-type fibres was positively correlated to the duty time and the number of bursts only for activations exceeding 20-30% of the maximum activity per day. Furthermore, cross-sectional areas of the slow-type fibres were positively correlated to the duty time for activations exceeding 30% of the maximum activity. The present data indicate that the amount of activation above a threshold (> 30% peak activity) is important for determining the fibre-type composition and cross-sectional area of slow-type fibres of a muscle. Activation above this threshold occurred only around 2% of the time in the jaw muscles, suggesting that contractile properties of muscle fibres are maintained by a relatively small number of powerful contractions per day.

Animals↗

PubMed2006

Acquired long QT syndrome and elective anesthesia in children.

We present the case of a child who had had a previous episode of torsades de pointes (TdP) and who was scheduled for elective surgery under general anesthesia. The pathophysiology of this condition and the anesthesia concerns are discussed. An 8-year-old male with a history of osteogenic sarcoma had undergone an uneventful limb salvage procedure 2 years earlier. During a subsequent admission to the hospital, he had had a cardiopulmonary arrest with complete recovery. Telemetry electrocardiogram (ECG) rhythm recordings obtained during the event showed TdP that degenerated into ventricular fibrillation, which then terminated spontaneously. On a subsequent ECG, the QTc interval was 694 ms. The prolonged QT interval was attributed to homeopathic use of cesium chloride supplements and the QT interval normalized after cesium was stopped. He presented for an elective procedure and, with an anesthetic plan that emphasized medications without known effect on the QT interval, had an uneventful perioperative course. The optimal anesthesia plan for patients with prolonged QT or those suspected to be at risk for prolongation of the QT interval has not been well described. Available evidence suggests that using total intravenous anesthesia with propofol may be the safest and was used uneventfully in this case. Additionally, this case emphasizes the need to inquire about the use of supplements and naturopathic medications, even in children, that may have life-threatening side effects or interactions with anesthetic agents.

Anesthesia, General↗

PubMed1983

A telemetric technique for studies of venous pressure in the human leg during different positions and activities.

The pressure in the saphenous vein of the lower leg was monitored by ordinary ECG telemetry equipment supplied with a pressure transducer, a chopper and an extra filter. In eight healthy volunteers venous pressure averaged 80 +/- 5 (SD) mmHg in the standing position and 21 +/- 10 (SD) mmHg during slow walking. When the subjects were occupied with laboratory work in upright position the mean venous pressure was 40-50 mmHg, similar to that obtained sitting at a desk: 48 +/- 5 (SD) mmHg.

Adult↗

PubMed1979

Fetal heart rate monitoring during ambulant labour using a modified adult radiotelemetry system.

A commercially available adult radiotelemetry system has been adapted successfully to allow continuous fetal heart rate monitoring during labour in ambulant patients. The modifications necessary to the adult equipment and its routine use in a large maternity unit are described. High quality recordings were obtained from 90% of the patients studied, with minimal inconvenience to the patient. The telemetry system combined the benefits of intrapartum fetal heart rate monitoring with those of ambulation during labour, decreasing the patient anxiety often associated with visible fetal monitoring.

Ambulatory Care↗

PubMed1997

Wireless control of functional electrical stimulation systems.

With the assistance of crutches and functional electrical stimulation (FES), we are able to restore standing and simple gait in some spinal cord injured (SCI) patients. In present rehabilitative systems, the patient divides the gait cycle into stance and swing phases via pushbuttons mounted on the handles of the crutches, which are hardwired to the functional electrical stimulator. The surface-mount technology based telemetry system, which makes use of the radiofrequency medium at 40 MHz, was developed to provide wireless control of the FES system. Signals from crutch pushbuttons were coded and transferred from the transmitter to the receiver. The receiver was firmly attached to the patient's waist and was connected to the stimulator.

Crutches↗

PubMedDate not supplied

Complex partial seizures in young children.

We retrospectively analyzed the clinical manifestations of complex partial seizures (CPS) in children aged < or = 10 years using video and EEG telemetry and evaluated their course, investigations, management, and seizure status at follow-up. Seventeen patients with CPS were studied at the Prince of Wales Children's Hospital (POWCH) and Prince Henry Hospital (PHH) between 1987 and 1992. Because 15 of the 17 patients had intractable seizures, the population was selective. Mean age was 6.5 years; 4 patients were aged < or = 2 years. Clinical features were normal or mild intellectual handicap (13); hemiplegia (5); and infantile spasms preceding CPS (4); of these, 2 also had simple partial motor seizures. Structural abnormalities were noted on scanning in 9 patients. Eighty-seven seizures were reviewed. Mean duration of each clinical seizure was 59.7 s (total population), 108 s (subgroup 1, aged < or = 2 years), and 48.5 s (subgroup 2, aged > 2 years). Major ictal manifestations were auras (9), staring (9), autonomic changes (6), and automatisms (17). In subgroup 1, automatisms were simple and mainly oroalimentary and gestural. Two patients had no change in surface ictal recordings, and 2 had normal interictal EEGs. At follow-up, 8 patients were seizure-free for 6 months, 1 was partially controlled (more than two seizures a month), and 8 had intractable seizures (two or more seizures a month). Seven patients underwent operation for intractable epilepsy, and 4 achieved a class 1A outcome (Engel classification).

Automatism↗

PubMed1997

FDG-positron emission tomography and invasive EEG: seizure focus detection and surgical outcome.

PURPOSE: To study the value of [18F]2-deoxyglucose (FDG)-positron emission tomography when surface ictal EEG is nonlocalizing. METHODS: FDG-PET scans were performed in 46 patients with complex partial seizures (CPS) not localized by ictal surface-sphenoidal video-EEG (VEEG) telemetry. Interictal PET was performed with continuous EEG monitoring, and images were analyzed with a standard template. Forty patients subsequently had subdural and 6 had depth electrodes (invasive EEG, IEEG); 22 had bilateral implants. A focus was detected in 40, and 35 had temporal lobectomy based on IEEG localization. RESULTS: There was a close association between IEEG and PET localization (p < 0.01): 26 patients had relative unilateral temporal FDG-PET hypometabolism, all had congruent IEEG, and 18 of 23 were seizure-free after temporal lobectomy. Five patients had unilateral frontotemporal hypometabolism (3 of 5 were seizure-free), 1 had frontal hypometabolism, and 14 had no lateralized PET abnormality (4 of 7 were seizure-free). Patients who became seizure-free had significantly higher lateral temporal asymmetry index (AI). PET showed > or = 15% relative temporal hypometabolism (AI) in 12 of 22 patients with nonlateralized surface ictal VEEG and was capable of distinguishing between frontal and temporal foci in 16 of 24 patients with lateralized, but not localized, surface ictal video-EEG. CONCLUSIONS: FDG-PET provides valuable data in patients with unlocalized surface ictal EEG and can reduce the number of patients who require IEEG studies. Quantitation is necessary for optimal PET interpretation.

Brain↗

PubMed1998

Semiology of temporal lobe seizures: value in lateralizing the seizure focus.

PURPOSE: To determine the lateralizing value of the clinical manifestations of seizures in patients with temporal lobe epilepsy (TLE), we made a retrospective videotape analysis of complex partial seizures (CPS) in 55 patients who underwent temporal lobectomy and were seizure-free postoperatively for >2 years. METHODS: Blinded to clinical details, we reviewed videotapes from video-EEG telemetry monitoring with attention paid to seizure semiology. RESULTS: Useful lateralizing features included unilateral clonic activity (with the seizure focus contralateral in all patients), unilateral dystonic or tonic posturing (with the seizure focus contralateral in 90 and 86%, respectively), unilateral automatisms (with the seizure focus ipsilateral in 80%), and ictal speech preservation (with the seizure focus contralateral to the language-dominant hemisphere in 80%). Versive head rotation occurring < or = 10 s before seizures secondarily generalized consistently predicted a contralateral focus. Seizure manifestations less predictive but suggestive of lateralization included ictal speech arrest and postictal speech status, with predictive values of 67%. Seizure manifestations not providing reliable lateralizing information included eye deviation, type of aura, and versive head movements occurring at times other than immediately before seizures secondarily generalized. CONCLUSIONS: In TLE, several clinical seizure manifestations are useful in lateralizing the seizure focus, although some provide no reliable information. Therefore, ictal semiology can assist in the evaluation of patients for seizure surgery, providing additional information in the lateralization of TLE.

Adolescent↗

PubMed1998

When should induction protocols be used in the diagnostic evaluation of patients with paroxysmal events?

PURPOSE: To determine the timing of spontaneous psychogenic nonepileptic events (PNEE) during video-EEG telemetry (VEEG), and the need to use induction protocols (IP). METHODS: We studied 100 consecutive patients (75 females, 25 males) admitted to our inpatient VEEG unit from July 1994 to June 1996 for differential diagnosis of paroxysmal events. We recorded the time to the first diagnostic spontaneous event, identified by the patient or a family member as typical. Episodes were classified as PNEE, physiologic nonepileptic events (PhysNEE), and epileptic seizures (ES). RESULTS: The mean duration of VEEG was 74+/-SD 54.1 h. In 82 patients, a diagnostic event occurred spontaneously. The first event was an ES in 22 patients, a PNEE in 53, and a PhysNEE in 7. The time to first diagnostic event was significantly shorter for PNEE than for ES [15.0+/-SD 16.3 h (range 5 min to 58 h) vs. 28.6+/-SD 34.0 h (range 1-110 h) F=15.621, p < 0.0001]. In the first 24 h, 77.4% of the patients with PNEE had an event. By 48 h, all but 2 (96.2%) had had diagnostic events. After the first 58 h of monitoring, all patients with PNEE experienced a spontaneous diagnostic event. CONCLUSION: Spontaneous events can be expected to occur within 48 h in most patients with PNEE. Therefore, if IP are to be used as a diagnostic tool, we suggest that they be withheld during the initial 48 h of VEEG monitoring.

Adolescent↗

PubMed1999

Depression in temporal lobe epilepsy before epilepsy surgery.

PURPOSE: This study examined the association of depression with laterality of epilepsy surgery in patients with temporal lobe epilepsy before standard lobectomy. METHODS: Forty-nine patients presented for EEG telemetry for localization of epilepsy and eventual temporal lobectomy. Patients underwent routine neuropsychiatric evaluation blinded for epileptic focus, including ratings on depression. Patients were grouped according to right (n = 25, M = 10/F = 15) and left (n = 24, M = 13/F = 11) temporal lobectomy. Analysis of variance included side of surgery as grouping variable and sex, general depressive, cognitive depressive, and vegetative depressive symptoms as dependent variables. Chi2 analyses included categoric variables of sex, handedness, education, neuropathologic findings, and current affective disorders. t Tests were performed on variables of age, epilepsy duration, and cognitive function. RESULTS: Right and left temporal epilepsy groups did not differ with regard to sex, handedness, age, duration of epilepsy, education, cognitive function, and neuropathology. Patients with right temporal epilepsy rated higher on general, cognitive. and vegetative depression scores. Women scored higher on general, cognitive, and vegetative depression scores. Current affective disorders were more common in the right temporal epilepsy group. CONCLUSIONS: Depression ratings and diagnoses were more prominent in patients with right temporal lobe epilepsy and in women in particular. The strength of this laterality finding lies in the selection of patients, as all underwent epilepsy surgery. The finding on gender difference partly reflects the higher incidence of depression in women and needs further exploration. The laterality finding contrasts with recent findings in epilepsy, stroke, and trauma that associate depression with left hemispheric lesions. However, our results are consistent with findings in electrically hyperactive lesions such as gelastic and dacrystic epilepsy.

Adolescent↗

PubMed1999

Electrophysiologic analysis of a chronic seizure model after unilateral hippocampal KA injection.

PURPOSE: Unilateral intrahippocampal injections of kainic acid (KA) in rats produce spontaneous recurrent limbic seizures and morphologic changes in hippocampus that resemble hippocampal sclerosis in patients with medically refractory mesial temporal lobe epilepsy (MTLE), that form of temporal lobe epilepsy (TLE) associated with hippocampal sclerosis. Interictal in vivo electrophysiologic studies have revealed high-frequency (250-500 Hz) oscillations, termed fast ripples (FRs). These oscillations may uniquely occur in or adjacent to the site of hippocampal KA injection, in areas that generate spontaneous seizures. Similar field potentials also have been demonstrated in the epileptogenic region of patients with TLE. We have now characterized ictal electrographic patterns in this rat model for comparison with those in human TLE and begun to evaluate the role of FRs in the transition to ictus in the KA-treated rat. METHODS: Rats received unilateral intrahippocampal injections of KA and, after the development of spontaneous seizures, were implanted with multiple fixed and moveable microelectrodes for single unit, field potential, and EEG recording. They were then monitored by using video-EEG telemetry for several weeks to capture and evaluate electrographic and behavioral seizure types. Results were correlated with Timm's stain demonstration of mossy fiber sprouting. RESULTS: Low-voltage fast (LVF) and hypersynchronous electrographic ictal-onset patterns were seen in the KA-treated rat that resembled similar ictal-onset patterns in patients with TLE. Hypersynchronous, but not LVF, ictal discharges were associated with recurrent FRs. As in the human, hypersynchronous ictal onsets originated predominantly in hippocampus, whereas LVF ictal onsets more often involved extrahippocampal structures. LVF ictal onsets occurred during wakefulness or paradoxical sleep and were usually associated with motor behavior, whereas hypersynchronous ictal onsets occurred during slow-wave sleep or periods of immobility and were not associated with motor behavior unless there was transition to another ictal electrographic pattern. Mossy fiber sprouting did not correlate with the frequency of ictal EEG discharges exhibited by each rat but was greater in those rats that demonstrated frequent behavioral seizures. CONCLUSIONS: The electrographic features of spontaneous seizures in the KA-treated rat resemble those of patients with medically refractory TLE with respect to EEG pattern and localization. Our data suggest that hypersynchronous ictal onsets represent epileptogenic disturbances in hippocampal circuits, whereas LVF ictal onsets may involve extrahippocampal areas having more direct connections to the motor system. Hypersynchronous seizures may involve the same neuronal mechanisms that generate interictal FRs.

Animals↗

PubMed2000

Twenty years of ictal EEG-EMG.

This study aimed to evaluate the use of ictal EEG recordings combined with simultaneous surface EMG in the diagnosis and analysis of motor events, both epileptic and nonepileptic. All ictal registrations were performed utilizing radio/cable telemetry. Routine recordings consisted of 18-channel EEG plus 8-channels bipolar surface EMG in freely moving patients. Combined ictal EEG-EMG recordings in freely moving patients enabled us to identify and define the following pathomechanisms of epileptic drop seizures, epileptic axial spasms, atonic, myoclonic-atonic, and akinetic seizures. Precise differentiation could be made between tonic and nontonic postural seizures and between startle-induced reflex seizures and hyperekplexia. The findings from telemetered ictal recordings in freely moving patients with combined EEG and surface EMG offer the only means of identifying, defining, and differentiating motor events, both epileptic and nonepileptic, of a short duration that cannot be properly differentiated by clinical examination alone.

Diagnosis, Differential↗

PubMed2000

Design of an intensive epilepsy monitoring unit.

Video-electroencephalography (EEG) telemetry is a crucial component in the comprehensive evaluation of patients with epilepsy. The reasons for patients needing to be monitored fall broadly into three groups: presurgical assessment (36% of our patients), diagnostic assessment (52%), and sleep disorders (12%). Video EEG can be used to differentiate unusual epilepsies from pseudo seizures or other causes of paroxysmal neurological events. The design of a unit depends on the case mix of patients expected to be referred. The key elements to a successful unit are a reliable, flexible, easy-to-use recording system and a team of dedicated, experienced staff, both nursing and technical. The unit at the National Hospital is a six-bed ward with 7 nurses to provide 24-hour coverage, 5 technicians working in shifts, and physics support. A minimum of two staff are on duty at all times. It operates on a five-day week with a throughput of approximately 500 patients per year. It is vital that investigations are performed as efficiently and effectively as possible, and the patient's safety and wellbeing is paramount at all times. Drug reduction is likely to be used to precipitate seizures, especially in those being considered for epilepsy surgery, and this poses a risk of provoked secondary generalized seizures. Continuous supervision of patients, and the ability to respond rapidly to a seizure, are therefore essential. We adopt a standardized easy-to-follow drug-reduction protocol, similar to that used by other centers.

Anticonvulsants↗

PubMed2006

Absence of seizures despite high prevalence of epileptiform EEG abnormalities in children with autism monitored in a tertiary care center.

PURPOSE: Children with autism are commonly referred for video-EEG monitoring to determine the precise nature of their seizure-like events. METHODS: We studied 32 children with autism by using continuous video-EEG telemetry (VEEG) monitoring at a tertiary care referral center. RESULTS: Of the 32 total patients, 22 were primarily referred for seizure evaluation and 10 for 24-h interictal EEG recording. Studies in two additional patients were prematurely terminated because of intolerance (they are not included in the analyses). The median monitoring duration was 1 day (range, 1-7 days). Of 22 patients referred for seizure evaluation, 15 had recorded events, but none was an epileptic seizure; the other seven patients had no recorded events. Interictal epileptiform EEG abnormalities were detected in 19 (59%) of 32 patients. These abnormalities included focal sharp waves (in eight patients), multifocal sharp waves (in six patients), generalized spike-wave complexes (in 11 patients), and generalized paroxysmal fast activity/polyspikes (in two patients). Focal/multifocal and generalized epileptiform abnormalities coexisted in six patients. Notably, 11 (73%) of the 15 patients with nonepileptic events had interictal epileptiform EEG abnormalities. CONCLUSIONS: Video-EEG evaluation of children with autism reveals epileptiform EEG abnormalities in the majority. However, many recorded seizure-like events are not epileptic, even in children with epileptiform EEG abnormalities.

Adolescent↗

PubMed1984

The marker channel: a telemetric diagnostic aid.

Interpretation of ECG records from patients who have sophisticated pacemakers is often difficult. To address this problem, radiofrequency telemetry of diagnostic data is now being provided in varying forms from such pacemakers. A particularly useful aid to ECG analysis is offered by transmission of a Marker Channel which provides detailed information regarding occurrence and timing of pacing and sensing events. Use of the Marker Channel in combination with an appropriate programmer makes it possible to obtain ECGs with fully diagrammed pacemaker operation in minutes, with sufficient detail to free the user from the need to memorize unique pacemaker characteristics. This system is described and sample records are discussed.

Arrhythmias, Cardiac↗