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PubMed1981

Evaluation of Corometrics 315 telemetry system for fetal monitoring.

The Corometrics 315 telemetry system is a commercially available unit which can transmit both fetal heart rate (FHR) and intrauterine or external pressure data to a standard fetal monitor. This system was evaluated in 40 patients, ten of whom were monitored simultaneously by telemetry and direct-wire fetal monitoring. Because of some differences in electronic engineering between the telemetry and direct fetal monitoring systems, the following differences were found: Comparison of the simultaneously obtained FHR recordings revealed that the telemetry system rejected most of the motion artifacts while maintaining true variability. There were no differences as regards readability, FHR, and beat-to-beat variability. The intrauterine pressure values were the same, although the telemetry system gave a smoother waveform with less motion artifact. The main advantages of the telemetry system were found to be: (1) The patient was free to move about and ambulate during labor. (2) It was possible to obtain uninterrupted monitoring while the patient was moved from the labor room to the delivery room and throughout the second stage of labor.

Evaluation Studies as Topic↗
PubMed2000

Evaluation of guidelines for the use of telemetry in the non-intensive-care setting.

To determine if the American College of Cardiology (ACC) cardiac monitoring guidelines accurately stratify patients according to their risks for developing clinically significant arrhythmias in non-intensive-care settings, we conducted a prospective cohort study of 2,240 consecutive patients admitted to a non-intensive-care telemetry unit over 7 months. Sixty-one percent of patients were assigned to ACC class I (telemetry indicated in most patients), 38% to class II (telemetry indicated in some), and 1% to class III (telemetry not indicated). Arrhythmias were detected in 13.5% of the class I patients, 40.7% of the class II patients, and 12% of the class III patients (p <.001). Telemetry detected an arrhythmia resulting in transfer to an intensive care unit in 0.4% of the class I patients, 1.6% of the class II patients, and none of the class III patients (p =.006). Telemetry led to a change in management for 3.4% of the class I patients, 12.7% of the class II patients, and 4% of the class III patients (p <.001). When patients with chest pain as the reason for admission were moved from class I to class II and patients with arrhythmias as the reason for admission were moved from class II to class I, more arrhythmias and more clinically significant arrhythmias occurred in class I patients and the trends from class I to class III were more consistent with the purpose of the guidelines. These findings indicate that when the ACC guidelines are reexamined, consideration should be given to changing them so they are more useful in non-intensive-care settings.

Arrhythmias, Cardiac↗
PubMedDate not supplied

Transient myocardial ischemia is an independent predictor of adverse in-hospital outcomes in patients with acute coronary syndromes treated in the telemetry unit.

OBJECTIVE: The purpose of this study was to determine whether transient myocardial ischemia (TMI) is predictive of adverse in-hospital outcomes among patients admitted to a telemetry unit with acute coronary syndrome (ACS). DESIGN AND SETTING: The study was designed as a prospective clinical trial in a telemetry unit of a large, urban, university medical center. SAMPLE: The sample was comprised of adult patients admitted to the telemetry unit for treatment of acute myocardial infarction, unstable angina, or coronary artery disease warranting cardiac catheterization or percutaneous coronary intervention. METHODS: Continuous 12-lead electrocardiographic (ECG) ST-segment monitoring was initiated in patients admitted to the telemetry unit. TMI was defined as a change in ST amplitude of > or = 100 microV (elevation or depression) in > or = 1 ECG lead lasting > or = 60 seconds, comparing a baseline 12-lead ECG with an event ECG. Frequencies, measurements of central tendency, t test, chi(2) test, and logistic regression analysis were used for data analysis. A P value of <.05 was adopted as the critical value to determine statistical significance. RESULTS: In 237 telemetry unit patients, 39 patients (17%) had ischemia. Overall, 46% of the patients with ischemia had in-hospital complications compared with 10% of the group without ischemia (P <.001). After controlling for other predictors of adverse outcomes (eg, age, gender, Norris prognostic indicator), patients with TMI were 8.5 times more likely to have in-hospital complications (95% CI, 3.71 to 19.71). CONCLUSION: TMI is an independent predictor of in-hospital complications among patients with ACS treated in the telemetry unit setting. Continuous 12-lead ECG ST-segment monitoring provides prognostic information for risk stratification of patients admitted to the hospital for treatment of ACS.

Adult↗
PubMed2006

Are the American College of Cardiology/Emergency Cardiac Care (ACC/ECC) guidelines useful in triaging patients to telemetry units?

PURPOSE: To determine if the ACC/ECC guidelines (1991) properly stratify patients according to risk of arrhythmia, defined as a single event on cardiac monitoring, and benefit, defined as a subsequent management change from a recorded telemetry event. SUBJECTS AND METHODS: In 2003, a prospective study of 217 consecutive patients admitted to a 24-bed telemetry unit was conducted for 25 days at a major academic hospital. Patients were categorized per ACC/ECC guidelines as appropriate (class I & II) or inappropriate (class III) based on a non-cardiologist admission diagnosis. A cardiologist-led group then reclassified patients at the time of admission using a brief interview. Continuous telemetry-recorded arrhythmias and resultant management changes were reviewed and recorded daily. Subgroup analysis of patients admitted with a chief complaint of chest pain was also performed. In 2004, after this trial was performed, the American Heart Association released a scientific statement updating practice standards for ECG monitor; however, this paper is based upon the original 1991 ACC/ECC guidelines. RESULTS: Reclassification significantly decreased the percentage of all class I & II patients from 91% to 71% (P<0.001) and the percentage of class I & II patients with chest pain from 100% to 58% (P<0.001) without increasing the percentage of arrhythmias occurring in class III patients. Class II patients had a statistically significant higher percentage of arrhythmias than class I and III patients before and after reclassification (P<0.001 and P<0.001, respectively). Management changes occurring as a direct result of telemetry events were higher in class II than class I or III patients before and after reclassification (P = 0.01 and P = 0.03). Life-threatening arrhythmias (sustained ventricular tachycardia or ventricular fibrillation) occurred in 1% of the 216 patients enrolled in this study. CONCLUSIONS: (1) Cardiology input using ACC/ECC guidelines and a brief interview at admission safely reduced total admissions primarily by identifying low risk chest pain admissions inappropriate for inpatient telemetry monitoring. (2) Life threatening arrhythmias occurring in patients admitted to telemetry are rare.

Arrhythmias, Cardiac↗
PubMed2003

Patient and nurse-related implications of remote cardiac telemetry.

The purposes of this study were (a) to determine the frequency of rhythm disturbance events among patients on remote cardiac telemetry, (b) to identify how many of these events were detected by the telemetry nurses, and (c) to explore the impact of managing telemetry on nurses' workload This prospective observational study took place in a nine-bed Coronary Respiratory Care Unit (CRCU) in a tertiary Canadian University Hospital. No lethal arrhythmias were detected during 420 hours of observation. There were a high number of remote telemetry warning arrhythmias, the vast majority of which were artifact (80.2%). A warning alarm occurred every 2.1 to 6.2 minutes. Nurses detected between 60% to 100% of valid warning alarms. Remote cardiac telemetry without a dedicated monitor-watcher places unnecessary demand on CRCU nurses' time because the vast majority of arrhythmia alarms are inconsequential. The addition of monitoring remote telemetry to the CRCU nurse's workload has the potential to negatively influence the care provided to CRCU patients.

Arrhythmias, Cardiac↗
PubMed2005

Telemetry monitoring during transport of low-risk chest pain patients from the emergency department: is it necessary?

BACKGROUND: Low-risk emergency department (ED) patients with chest pain (CP) are often transported by nurses to monitored beds on telemetry monitoring, diverting valuable resources from the ED and delaying transport. OBJECTIVES: To test the hypothesis that transporting low-risk CP patients off telemetry monitoring is safe. METHODS: This was a secondary analysis of a prospective, observational cohort of ED patients with low-risk chest pain (no active chest pain, normal or nondiagnostic electrocardiogram, normal initial troponin I) admitted to a non-intensive care unit monitored bed who were transported off telemetry monitor by nonclinical personnel. A protocol allowing transportation of low-risk CP patients off telemetry monitoring to a monitored bed was developed, and an ongoing daily log of patients transported off telemetry was maintained for the occurrence of any adverse events en route to the floor. Adverse events requiring treatment included dysrhythmias, hypotension, syncope, and cardiac arrest. The study population included patients who presented during September-October 2004, whose data were abstracted from the medical records using standardized methodology. A subset of 10% of the medical records were reviewed by a second investigator for interrater reliability. Death, syncope, resuscitation, and dysrhythmias during transport or immediately on arrival to the floor were the outcomes measured. Descriptive statistics and confidence intervals (CIs) were used in data analysis. RESULTS: During the study period, 425 patients had CP of potentially ischemic origin, of whom 322 (75.8%) were low risk and met the inclusion criteria and were transported off monitors. Their mean (+/-standard deviation) age was 58.3 (+/-16.0) years; 48.1% were female. During transport from the ED, there was no patient with any adverse events requiring treatment and there was no death (95% CI = 0% to 0.93%). CONCLUSIONS: Transportation of low-risk ED chest pain patients off telemetry monitoring by nonclinical personnel to the floor appears safe. This may reduce diversion of ED nurses from the ED, helping to alleviate nursing shortages.

Cardiac Catheterization↗
PubMedDate not supplied

[Study of patients admitted to a telemetry unit].

The current situation of the telemetry unit of Vigil de Quiñones Hospital was studied. Telemetry indications, results, and problems observed since the unit was inaugurated were studied to determine the usefulness of telemetric heart rate monitoring and centralized surveillance in an intensive care unit (ICU) in detecting severe arrhythmias, controlling antiarrhythmic treatment, and evaluating why and to what extent telemetry is clinically useful. In our center, telemetry is used to monitor patients with well-established needs. In most cases, arrhythmias are monitored, most frequently premature ventricular complexes, sinus bradycardia and supraventricular tachycardia. Telemetry was useful in arrhythmia treatment and the follow-up of patients with temporary or permanent pacemakers. In a significant percentage of patients (8.62%), telemetry was the key to their ICU admission and, possibly, their survival. There were generally few problems with signal transmission.

Age Distribution↗
PubMed2000

New frequencies for medical telemetry. FCC's plan is final--now what?

The frequency bands used by wireless medical telemetry in the United States are getting crowded. More and more competing users are occupying those frequencies, putting medical telemetry at an ever-greater risk for harmful interference. In our May 2000 Evaluation of physiologic monitoring systems, we discussed the U.S. Federal Communications Commission's (FCC) proposal to allocate new frequency bands in which medical telemetry could operate in the United States as a primary user. (Being a primary user means that medical telemetry is protected against interference from other sources in the specified frequency bands.) On June 12, 2000, FCC released a Report and Order (FCC No. 00-211) making new frequencies available for medical telemetry use on a primary basis. These new frequencies, called the Wireless Medical Telemetry Service, will be administered by a frequency coordinator and should help alleviate the crowding of available frequencies. The final rules presented in the Report and Order will go into effect on October 16, 2000. In this article, we discuss why these new frequencies are needed and what you should do about them.

Government Agencies↗
PubMed2002

Association of transient myocardial ischemia with adverse in-hospital outcomes for angina patients treated in a telemetry unit or a coronary care unit.

BACKGROUND: Little is known about the frequency or consequences of transient myocardial ischemia in patients admitted to a telemetry unit for treatment of angina. OBJECTIVES: To compare the rate of transient myocardial ischemia in a group of patients with angina treated in a telemetry unit with the rate in a similar group treated in a coronary care unit and to determine if transient myocardial ischemia is associated with adverse in-hospital outcomes. METHODS: Continuous 12-lead electrocardiography was used to monitor changes in the ST segment in 186 patients in the coronary care unit (1994-1996) and 186 patients in the telemetry unit (1997-2000). Transient myocardial ischemia was defined as a change from baseline of 100 microV or more in the ST segment in 1 or more leads lasting 60 seconds or longer RESULTS: The rate of transient myocardial ischemia was 15% for patients in the telemetry unit and 19% for patients in the coronary care unit. Regardless of hospital unit, patients with transient myocardial ischemia were more likely than those without this complication to experience death or acute myocardial infarction after hospital admission. Most patients did not experience signs or symptoms during transient myocardial ischemia: 71% of patients in the telemetry unit versus 58% of patients in the coronary care unit (P =.28). CONCLUSIONS: Transient myocardial ischemia is common among patients with angina treated in a telemetry unit. ST-segment monitoring may be useful for detecting patients with ischemia who may benefit from more aggressive therapies aimed at abolishing ongoing ischemia.

Aged↗
PubMed2003

[Effects of ocular hypotensive agents on the circadian rhythm in intraocular pressure in rabbits as measured by telemetry].

PURPOSE: To establish a telemetry system for measuring intraocular pressure (IOP) in rabbits and to evaluate the effects of topical application of ocular hypotensive agents on the circadian rhythm of IOP. SUBJECTS AND METHODS: We developed a telemetry system in rabbits housed under a 12-hour light-dark cycle (light and dark phases: 7:00-19:00, 19:00-7:00, respectively). The IOP resulting from a single topical application of ocular hypotensive agents was measured by telemetry during the light phase and the dark phase. RESULTS: The values measured by the telemetry were positively correlated to the value of the anterior chamber pressure measured by a transducer in range from 5 to 50 mmHg (r = 0.987). A single topical application of timolol maleate (0.5%), dorzolamide hydrochloride (1%), and dipivefrine hydrochloride (0.1%) caused no significant reduction in IOP in the light phase, but they did in the dark phase. A single topical application of bunazosin hydrochloride (0.01% or 0.1%) had significant ocular hypotensive effects in both phases. CONCLUSION: These findings indicate that the different effects of ocular hypotensive agents on circadian rhythms of IOP can be measured by the telemetry. Telemetry may be useful for evaluation of ocular hypotensive agents and the circadian rhythm of IOP.

Animals↗
PubMed1982

Plaque sampling and telemetry for monitoring acid production on human buccal tooth surfaces.

The plaque sampling method and wire telemetry using miniature, glass pH electrodes on the buccal surface of mandibular first permanent molars, compared human dental plaque pH responses to a 10 per cent solution of sucrose. Nine subjects abstained from oral hygiene and were tested in morning sessions on 5 consecutive days. The mean resting plaque pH value for all sessions by plaque sampling was 6.60 +/- 0.18 (mean +/- SD) and by telemetry was 6.56 +/- 0.19. After a 1 min sucrose rinse, 1-day-old plaque showed a decrease in pH approx. 5.5 by both methods. The 2-, 3-, 4- and 5-day-old plaque, the mean minimum pH achieved was 4.69 +/- 0.28 as measured by sampling and 3.94 +/- 0.49 as determined by telemetry. The times taken to reach minimum pH as determined by the two methods were almost identical. The electrode calibration data showed that all the telemetry electrodes responded consistently for all 5 days of study. Scanning electron microscopy and microbiological analysis of electrode tips and enamel replicas revealed that plaque accumulated on glass at the same rate with a similar bacterial composition to plaque formed on clean enamel. It is proposed that glass microelectrodes and wire telemetry are a reasonable means for continuously monitoring plaque pH in situ. Comparison with plaque sampling suggested that telemetric responses reflect the type of plaque which accumulates at particular sites on the dentition.

Adult↗
PubMed2004

Lack of utility of telemetry monitoring for identification of cardiac death and life-threatening ventricular dysrhythmias in low-risk patients with chest pain.

STUDY OBJECTIVE: Low-risk patients with chest pain are often admitted to monitored beds; however, the use of telemetry beds in this cohort is not evidence based. We tested the hypothesis that monitoring admitted low-risk patients with chest pain for dysrhythmia is low yield (<1% detection of life-threatening dysrhythmias requiring treatment). METHODS: We conducted a prospective cohort study of emergency department (ED) patients with chest pain with a Goldman risk score of less than 8%, a normal initial creatine kinase-MB level, and a negative initial troponin I level admitted to non-ICU monitored beds. Investigators followed the hospital course daily. The main outcome was cardiovascular death and life-threatening ventricular dysrhythmia during telemetry. RESULTS: Of 3,681 patients with chest pain who presented to the ED, 1,750 patients were admitted to non-ICU monitored beds. Of these, 1,029 patients had a Goldman risk score of less than 8%, a troponin I level of less than 0.3 ng/mL, and a creatine kinase-MB level of less than 5 ng/mL (accounting for 59% of all chest pain telemetry admissions). During hospitalization, there were no patients with sustained ventricular tachycardia/ventricular fibrillation requiring treatment on the telemetry service (0%; 95% confidence interval [CI] 0% to 0.3%). There were 2 deaths: neither was cardiovascular in nature or preventable by monitoring (cardiovascular preventable death rate=0%; 95% CI 0.0% to 0.3%). CONCLUSION: The routine use of telemetry monitoring for low-risk patients with chest pain is of limited utility. Admission to nonmonitored beds might help alleviate ED crowding without increasing risk of adverse events caused by dysrhythmia in patients with a Goldman risk of less than 8%, an initial troponin I level of less than 0.3 ng/mL, and a creatine kinase-MB level of less than 5 ng/mL.

Arrhythmias, Cardiac↗
PubMed2002

Continuous Holter telemetry of atrial electrograms and marker annotations using a common Holter recording system: impact on Holter electrocardiogram interpretation in patients with dual chamber pacemakers.

The impact of continuous telemetry of atrial electrogram and marker annotations on Holter ECG interpretation was assessed in 98 patients with bipolar dual chamber pacemakers (VDD pacemakers n = 29, DDD(R) systems n = 69). Atrial electrogram and marker annotations were continuously sampled by a telemetry coil that was externally positioned on the pacemaker pocket, amplified, and transduced to a three-channel Holter ECG recorder in addition to an ECG recording. Holter tapes were analyzed by two experienced investigators for quality of P wave recognition and episodes suspicious of pacemaker dysfunction. Initially, only the ECG channel was analyzed. Thereafter, results were compared to those achieved on the basis of the complete recording including atrial electrogram and marker annotations. Recognition of atrial rhythm was markedly improved by Holter telemetry. During 99.3% of recording time telemetry showed a satisfying quality, whereas ECG alone allowed a reliable P wave recognition only during 84.4% of recording time (P < 0.001). One hundred twenty-nine episodes suspicious of pacemaker malfunction occurred in 17 of 98 patients. By analysis of ECG, only 78.3% of episodes were concordantly classified by the investigators. However, 98.4% of all episodes were properly identified when atrial electrogram and marker annotations were added to the analysis (P < 0.001). In particular, discrimination between atrial undersensing, sinus bradycardia, and atrial sensed events within the refractory periods was facilitated. Holter telemetry of atrial electrogram and marker annotations facilitates the analysis of Holter ECGs in pacemaker recipients and improves the detection of pacemaker dysfunctions.

Aged↗
PubMedDate not supplied

Problems with telemetry monitoring systems.

The purchaser of telemetry monitoring systems for operating and recovery rooms has little information available on the practical aspects of ownership and usage. To explore this problem, we recorded 76 telemetry failures (both operator and machine failure) occurring over six months among 18 telemetry channels located in operating and recovery rooms. We experienced approximately one telemetry failure every three days or every 60 surgical procedures. Factory repairs were required on 29 transmitters and 19 receivers during a two-year period. We observed that 28% of the failures were attributable to lead and electrode problems, 25% to battery depletion, 22% to mechanical or electronic component failures, 12% to inappropriate control settings and frequency mismatching, and 13% to miscellaneous difficulties. The following problems were observed. Transmitters were dropped frequently and occasionally immersed in liquids. Thus, waterproofing is recommended for OR use, and lead-failure warning circuitry is mandatory. Inappropriate control settings and frequency mismatching led to a previously unrecognized hazard: that is, it is possible to receive and display ECG data from the wrong patient located in a distant room. (Stethoscopic monitoring can be used to confirm that the data being displayed are from the correct patient.) Battery failure can occur at inopportune times, e.g., during cardiac arrest. Transmitters are frequently "lost" because of their small size and high mobility. This study indicated to us that, in the operating room, telemetry is not desirable because of its high cost compared to hard wired systems, poor reliability, and the possible hazard of displaying data from the wrong patient if improperly used.

Biomedical Engineering↗
PubMed1997

Telemetry augments the validity of the rat as a model for heat acclimation.

Repeated exposure to heat stress results in physiological adaptations which increase tolerance to heat stress. Core temperature (Tc) and heart rate (HR), two indices of successful heat acclimation, are both increased by the handling and restraint usually required to measure these variables in the rat. This study compares measurement of these variables in telemetry- and nontelemetry-equipped heat-acclimated rats. Four groups of male Sprague-Dawley rats were used: CAC (24, control for acclimated), HAC (24, heat acclimated), TCAC (3, telemetry implanted control for acclimation), and THAC (3, telemetry implanted, heat acclimated). The CAC and TCAC rats were maintained at 26 degrees C for 2 weeks; HAC and THAC groups were maintained at 32-33 degrees C for 2 weeks. The telemetry rats were surgically implanted with transmitters which measured activity, temperature, blood pressure (BP), and ECG. Following acclimation, the rats were subjected to a heat-stress test as follows: animals were placed in a chamber maintained at 41.5 degrees C until a Tc of 41.5 degrees C was reached, when the animals were removed to a 26 degrees C chamber to recover. The Tc of the CAC and HAC rats was manually measured with a rectal probe every 15 min. The TCAC and THAC rats had Tc, HR, and BP monitored electronically every 2.5 min from 30 min prior to heat stress through 30 min after heat. The THAC rats maintained lower Tc, HR, and BP than the TCAC rats throughout the heat stress. The CAC and HAC rats had higher Tc and slower rates of cooling after heat than either of the telemetry groups. Simultaneous measurement of HR, BP, and Tc has not previously been reported in unrestrained heat-acclimated rats. Measurement of these variables without the confounding effects of restraint or handling has increased the validity of the rat as a model for human heat acclimation.

Animals↗
PubMed2005

Limited benefits of ambulance telemetry in delivering early thrombolysis: a randomised controlled trial.

OBJECTIVES: To evaluate the potential of a continuous telemetry system linking rural ambulances to a coronary care unit to reduce call to thrombolysis times. METHODS: This prospective randomised controlled trial recruited patients using the 999 ambulance service in a rural area of the UK with signs or symptoms of coronary heart disease. Subjects were assigned to receive either standard paramedic treatment or transmission of 12 lead ECG, blood pressure, pulse oximetry, and relevant medical history to a general hospital coronary care unit. Cardiology senior house officers then determined each patient's suitability for pre-hospital thrombolysis time, and transmitted this decision back to the ambulance. This was documented as the potential thrombolysis, although no thrombolytic agents were administered by paramedics. The between groups difference in time to potential thrombolysis (intervention group) and actual thrombolysis (controls) was compared. The proportion of intervention group subjects ultimately receiving thrombolysis in hospital was compared with that recommended for pre-hospital thrombolysis. RESULTS: The potential reduction in call to treatment time for telemetry patients recommended for pre-hospital thrombolysis was 55 minutes (p = 0.022). Following hospital admission,21/213 of the telemetry patients were thrombolysed (10%, 95% confidence interval (CI) 6% to 15%). Of these patients, 3/21 received a recommendation for thrombolysis in the ambulance (14%, 95% CI 3.1% to 36.3%). The sensitivity and specificity of the telemetry system in detecting patients requiring thrombolysis was 13.6 and 99.5% respectively. Errors were made in the pre-hospital treatment recommendations for two patients. CONCLUSIONS: Continuous telemetry systems may significantly reduce call to treatment times for patients recommended for pre-hospital thrombolysis in a rural setting. However, this benefit must be balanced against the very small proportion of eligible patients identified as suitable for pre-hospital thrombolysis. This limitation may be due to communications problems, the criteria used to identify eligible patients, or the seniority of physicians tasked with making treatment decisions.

Aged↗
PubMed2004

A self-calibrating telemetry system for measurement of ventricular pressure-volume relations in conscious, freely moving rats.

Using Bluetooth wireless technology, we developed an implantable telemetry system for measurement of the left ventricular pressure-volume relation in conscious, freely moving rats. The telemetry system consisted of a pressure-conductance catheter (1.8-Fr) connected to a small (14-g) fully implantable signal transmitter. To make the system fully telemetric, calibrations such as blood resistivity and parallel conductance were also conducted telemetrically. To estimate blood resistivity, we used four electrodes arranged 0.2 mm apart on the pressure-conductance catheter. To estimate parallel conductance, we used a dual-frequency method. We examined the accuracy of calibrations, stroke volume (SV) measurements, and the reproducibility of the telemetry. The blood resistivity estimated telemetrically agreed with that measured using an ex vivo cuvette method (y=1.09x - 11.9, r2= 0.88, n=10). Parallel conductance estimated by the dual-frequency (2 and 20 kHz) method correlated well with that measured by a conventional saline injection method (y=1.59x - 1.77, r2= 0.87, n=13). The telemetric SV closely correlated with the flowmetric SV during inferior vena cava occlusions (y=0.96x + 7.5, r2=0.96, n=4). In six conscious rats, differences between the repeated telemetries on different days (3 days apart on average) were reasonably small: 13% for end-diastolic volume, 20% for end-systolic volume, 28% for end-diastolic pressure, and 6% for end-systolic pressure. We conclude that the developed telemetry system enables us to estimate the pressure-volume relation with reasonable accuracy and reproducibility in conscious, untethered rats.

Animals↗
PubMed1996

Telemetry monitoring of pulmonary arterial pressure in freely moving rats.

Several rat models of pulmonary hypertension have been developed. However, up until now it has been difficult to monitor pulmonary arterial pressure for long periods of time. The goal of the present study was to develop a telemetry system allowing chronic monitoring of pulmonary arterial pressure in freely moving rats. For this purpose, while animals were under anesthesia, a sensing catheter was implanted into the pulmonary arterial trunk through the right ventricle. This catheter was connected to an emitter implanted in the abdomen. Validation of the system was performed in three steps. First, acutely, we controlled that the pressure signal transmitted by the telemetry system was accurate and corresponded to a signal obtained with a high-fidelity Millar catheter. Second, we evaluated the chronic consequences of implantation of the system. Third, we used the system to monitor pulmonary arterial pressure in a model of monocrotaline-induced hypertension in which the effects of bosentan, an endothelin-receptor antagonist, were evaluated. The telemetry system was reliable and did not lead to damage of the right ventricle and/or to chronic pulmonary embolism. After a recovery period of 8-10 days, mean pulmonary arterial pressure was stable. With the use of this telemetry system, it was possible to follow the increase of pulmonary arterial pressure induced by monocrotaline. In this model, bosentan decreased mean pulmonary arterial pressure by 13% (P = 0.07), suggesting a role of endothelin in this model of pulmonary hypertension. We conclude that it is possible to use this telemetry system to monitor pulmonary arterial pressure in freely moving conscious rats.

Animals↗