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PubMed2003

Chronic experiences with a single lead dual chamber implantable cardioverter defibrillator system.

Monitoring of atrial rhythm in patients implanted with ICDs may improve accuracy in identifying supraventricular arrhythmias and, therefore, prevent inappropriate therapies. Since difficulties were found in dual chamber ICDs with separate leads, a new designed single lead dual chamber ICD system was tested. Twenty-five patients implanted with a Deikos A+ (single coil defibrillation lead with two atrial sensing rings combined with a dual chamber ICD with a high amplifying atrial channel) were tested. Atrial and ventricular signals were analyzed during sinus rhythm (SR) and sinus tachycardias (STs), atrial flutter and AF, and VT or VF. Follow-ups were performed after 1, 3, 6, 9, and 12 months after implantation. Analysis of EGM amplitudes of stored episodes revealed that atrial signals during atrial flutter (2.1 +/- 0.51 mV) were comparable to those of ST (2.2 +/- 0.5 mV). Atrial amplitudes during AF were significantly lower (0.81 +/- 0.5 mV, P<0.01). During VF atrial "sinus" signals (2 +/- 0.8 mV) were stable. Ventricular parameters did not differ from a standard ICD lead; defibrillation threshold was 11.4 +/- 4.5 J (16 patients). During intraoperative and prehospital discharge measurements, 97.1% of SR-P waves and 99.2% of atrial flutter waves were detected correctly. In AF 91.11% of atrial signals were detected. Analysis of 505 stored episodes showed that 96.8% of ST and 100% of atrial flutter and 100% of AF episodes have been classified correctly and no underdetection of VT/VF was found. The first experiences with the new VDD-ICD system show an increase of the specificity to detect ventricular tachycardias to a level comparable to dual chamber ICDs with two leads. The reliability of this system has to be proven in a prospective randomized study.

Defibrillators, Implantable↗
PubMed1994

EMIT cyclosporine assay: development of an application protocol for Technicon AXON System.

Monitoring parent drug cyclosporine (CsA) concentrations in whole blood has been facilitated by the introduction of automated nonisotopic immunoassays [fluorescence polarization monoclonal whole blood assay (FPIA), EMIT Cyclosporine Assay]. The latter assay currently has a defined application only for Cobas Mira Chemistry Systems. The purpose of our work was to develop an application for this assay on the Technicon AXON. Instrument settings were optimized to arrive at the following assay performance characteristics. Limit of sensitivity was 50 micrograms/L. Interassay coefficients of variation (CV) were 11.2% (n = 16; mean = 81 micrograms/L) and 9.4% (n = 16; mean = 418 micrograms/L). Recoveries of 102, 112, and 117% were obtained by spiking aliquots of 10 whole blood patient pools of known CsA concentrations with 50, 100, and 200 micrograms/L CsA, respectively. Serial dilutions of two patient specimens demonstrated a linear relationship between expected and actual CsA concentrations (r = 0.996, 0.998; regression lines; y = 0.989x + 11.7; y = 0.979x + 9.5). Carryover and interference (lipemia) were not evident. Instrument calibration stability is at least 1 month. Comparison with CsA concentrations analyzed in renal transplant patients by the FPIA assay produced a linear regression equation of EMIT = 1.113x - 44.5, r = 0.968, Sy/x = 20.8, n = 32. Comparison with high-performance liquid chromatography (HPLC)-derived values in the same patient population produced a linear regression equation of EMIT = 1.114x - 16.4, r = 0.970, Sy/x = 20.2. FPIA-derived CsA concentrations averaged 14.2% more than those obtained with the EMIT method with the latter averaging 1.3% more than HPLC values.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1999

A noninvasive radiotelemetry system to monitor heart rate for assessing stress responses of bovines.

A noninvasive radiotelemetry system was developed to monitor heart rates of cows and to view and analyze data. The system was validated by comparing heart rate data of two restrained heifers collected simultaneously using telemetric and direct electrocardiogram measurements and by acquiring data over 72 h from two dry cows housed in an experimental handling facility consisting of a free-stall pen, a holding pen, a pass-through stall, and a second holding pen. Telemetric and direct measurements in response to pharmacological elevation of heart rates were essentially identical. For cows in the experimental facility, peristimulus-time histograms indexed to standing or lying showed that average heart rates for cows increased 4.0 +/- 1.4 beats/min after cows stood and decreased 4.8 +/- 1.0 beats/min after cows lay. Similarly, the average heart rate for the cow naive to the facility increased from 60 to 86 beats/min and remained elevated for 6.3 min when heart rate was indexed to maximal heart rate within +/- 3 min of entry into the pass-through stall. Heart rate for the naive cow increased consistently from around 60 to over 160 beats/min during repeated agonistic encounters between animals. Heart rate for the other cow was not affected by the encounters. These results show clearly that heart rate can be used to monitor animal anxiety.

Animals↗
PubMedDate not supplied

A portable system for monitoring physiological responses to hypoglycaemia.

Hypoglycaemia is the most common complication affecting people with Type 1 insulin dependent diabetes mellitus. Its onset is characterized by symptoms which include sweating, tremor, palpitations, loss of concentration and tiredness. As part of a research project to investigate the mechanisms of hypoglycaemia we have developed an ambulatory system to monitor and record pulsatile changes in blood flow, pulse interval, body temperature and skin impedance. The system uses a pocket computer (Atari Portfolio) to collect and store the data on a memory card. The analogue system consists of two thermocouples, an infrared photoplethysmograph and skin impedance monitoring circuit. To conserve power the system is programmed to make measurements for 2 min every 10 min: using this regimen over 16 h of data can be stored. Data collected during a spontaneous overnight hypoglycaemic episode are presented and also a comparison between continuous and intermittent data collection during a period of induced hypoglycaemia. The system is being used to investigate the physiological responses to hypoglycaemia but could easily be adapted for monitoring other physiological signals.

Arrhythmias, Cardiac↗
PubMed2003

Communication monitoring: shaping CDC's emergency risk communication efforts.

CDC develops and delivers health messages for a variety of audiences, including the public, health care professionals, public health researchers and practitioners, and policy makers. News media outlets--because of their broad reach and potential to influence knowledge, attitudes, and behaviors--are major channels for disseminating messages to these audiences. CDC has routinely monitored news outlets to identify message/information gaps and opportunities. The 9/11 terrorist attacks and the anthrax incidents that followed required CDC to transform its media monitoring system into a broader communication monitoring system, with both listening and telling functions, to support CDC's public health emergency response.

Anthrax↗
PubMed1996

Dose monitoring for boron neutron capture therapy using a reactor-based epithermal neutron beam.

The aims of this study were (i) to determine the variation with time of the relevant beam parameters of a clinical reactor-based epithermal neutron beam for boron neutron capture therapy (BNCT) and (ii) to test a monitoring system for its applicability to monitor the dose delivered to the dose specification point in a patient treated with BNCT. For this purpose two fission chambers covered with Cd and two GM counters were positioned in the beam-shaping collimator assembly of the epithermal neutron beam. The monitor count rates were compared with in-phanton reference measurements of the thermal neutron fluence rate, the gamma-ray dose rate and the fast neutron dose rate, at a constant reactor power, over a period of 2 years. Differences in beam output, defined as the thermal neutron fluence rate at 2 cm depth in a phantom, of up to 15% were observed between various reactor cycles. A decrease in beam output of about 5% was observed in each reactor cycle. An unacceptable decrease of 50% in beam output due to malfunctioning of the beam filter assembly was detected. For safe and accurate treatment of patients, on-line monitoring of the beam is essential. Using the calibrated monitor system, the standard uncertainty in the total dose at depth due to variations with time of the beam output parameters has been reduced to a clinically acceptable value of 1% (one standard deviation).

Boron Neutron Capture Therapy↗
PubMed2004

Development of a new experimental system for monitoring biomembrane reactions: combination of laser spectroscopic techniques and biomembrane models formed at an oil/water interface.

We present a new experimental system to observe reactions in biomembranes by combining laser spectroscopic techniques with phospholipid monolayers formed at oil/water interfaces. The system can monitor reactions through changes in interfacial tension at oil/water interfaces induced by the reactions under non-destructive and non-contact conditions. In addition, oil/water interfaces with defined areas can define the composition of different kinds of phospholipids. Furthermore, the system allows using, as an oil phase, alkanes whose number of carbon atoms is close to the number of the alkyl chains of phospholipids in biomembranes (C > or = 16). We demonstrated the hydrolysis reaction in DPPC (dipalmitoyl phosphatidylcholine)/DPPS (dipalmitoyl phosphatidylserine)-mixed monolayers by phospholipase A2 by using the system.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2002

A system for rapid large-area monitoring of gamma dose rates in the environment based on MCP-N (LiF:Mg,Cu,P) TL detectors.

One lesson learned from the Chernobyl accident was that the spatial distribution of far-field contamination was strongly non-uniform due to local variation of atmospheric conditions, such as wind direction, rain etc. An environmental monitoring system using highly sensitive thermoluminescent LiF:Mg,Cu,P (MCP-N) detectors has been completed and field-tested. The system consists of 3000 MCP-N detectors in 1000 TLD cards (three TLDs per card), two Mikrolab automatic TL readers, heating ovens, and specially developed software which includes a database for rapid evaluation of results. The main dosimetric parameters of MCP-N dosemeters, such as thermally-induced fading, light sensitivity, minimum detectable dose, self-dose, zero-dose, energy response up to 6-7 MeV, influence of annealing and readout conditions on detector stability, have been tested. About 100 locations over an area of about 15,000 km2 in the south of Poland were selected for measurements lasting from 4 days to 3 months. The kerma rates measured over a 4 day screening period agree well with kerma rates determined over a 75 day monitoring period. Results from short- and long-term exposure periods agree well with those performed using MTS-N (LiF:Mg,Ti) over southern Poland in 1985, before the Chernobyl accident. Thus, using the system based on MCP-N detectors, one is able simultaneously to monitor environmental radiation kerma rates at a large number of locations over periods of four days or less. Provided natural background kerma rates at selected monitoring points are available prior to the accident, the system can be applied to assess kerma rates rapidly in the environment, following a nuclear accident.

Calcium↗
PubMedDate not supplied

[Criteria of the accuracy of measurement of cardiocycle duration in systems for monitoring of cardiac rhythm variability parameters].

The use of the criteria of the accuracy of measurement of cardiocycle duration in systems for monitoring of cardiac rhythm variability parameters based on no more than 10% deviation of diagnostic characteristics was shown to provide the measuring error of no more than 4 msec at histogram grouping interval 10 msec. An increase in the grouping interval duration causes a decrease in the sensitivity of diagnostic parameters to patient state and diagnostic mistakes.

Heart↗
PubMed1994

Automated imunoanalysis systems for monitoring mammalian cell cultivation processes.

Two different automated immunoanalysis systems are presented. Both are based on the principles of flow-injection analysis and were developed to provide reliable, rapid monitoring of relevant proteins in animal cell cultivation processes. One system uses a turbidimetric analysis, and the other employs a heterogeneous chemistry with immobilized immunocomponents. For both systems, the analysis time is in the range of a few minutes, and a complete analysis cycle, including triplicate analyses and various washing steps, is in the range of 20-30 minutes. Samples from cultivation processes can be analyzed directly without dilution. Quantitation of proteins such as rt-PA or monoclonal antibodies can be performed over an analyte concentration range of 1-1000 mg/L. Both systems were compared to conventional ELISA assays on microtiter plates. The turbidimetric analysis system also included a biosensor for simultaneous glucose determination.

Animals↗
PubMedDate not supplied

Oncology/quality assurance: a quality system for oncology nursing.

The benefits of three quality monitoring systems, Monitor, Qualpacs and the Dynamic Standards Setting System are explored in relation to oncology nursing. The author concludes that the flexibility provided by the 'bottom-up' design of the Dynamic Standards Setting System is admirably suited to the needs of nurses working with cancer patients.

Humans↗
PubMedDate not supplied

Monitoring expert system performance using continuous user feedback.

OBJECTIVE: To evaluate the applicability of metrics collected during routine use to monitor the performance of a deployed expert system. METHODS: Two extensive formal evaluations of the GermWatcher (Washington University School of Medicine) expert system were performed approximately six months apart. Deficiencies noted during the first evaluation were corrected via a series of interim changes to the expert system rules, even though the expert system was in routine use. As part of their daily work routine, infection control nurses reviewed expert system output and changed the output results with which they disagreed. The rate of nurse disagreement with expert system output was used as an indirect or surrogate metric of expert system performance between formal evaluations. The results of the second evaluation were used to validate the disagreement rate as an indirect performance measure. Based on continued monitoring of user feedback, expert system changes incorporated after the second formal evaluation have resulted in additional improvements in performance. RESULTS: The rate of nurse disagreement with GermWatcher output decreased consistently after each change to the program. The second formal evaluation confirmed a marked improvement in the program's performance, justifying the use of the nurses' disagreement rate as an indirect performance metric. CONCLUSIONS: Metrics collected during the routine use of the GermWatcher expert system can be used to monitor the performance of the expert system. The impact of improvements to the program can be followed using continuous user feedback without requiring extensive formal evaluations after each modification. When possible, the design of an expert system should incorporate measures of system performance that can be collected and monitored during the routine use of the system.

Expert Systems↗
PubMed2005

Electroactive fabrics for distributed, comfortable and interactive systems.

Monitoring body kinematics has fundamental relevance in several biological and technical disciplines. In particular the possibility to know the posture exactly may furnish a main aid in rehabilitation topics. In the present work a collection of innovative and unobtrusive garments able to detect the posture and the movement of the human body are introduced. This paper deals with the design, the development and the realization of sensing garments, from the characterization of innovative comfortable and spreadable sensors to the methodologies employed to gather information on the posture and movement. Several new algorithms devoted to the device operation are presented and tested. Data derived from the sensing garment are analyzed and compared with the data derived from a traditional movement tracking system.

Biomechanical Phenomena↗
PubMed2005

A modified, dual reporter TOXCAT system for monitoring homodimerization of transmembrane segments of proteins.

The TOXCAT assay system developed by Russ and Engelman [TOXCAT: a measure of transmembrane helix association in a biological membrane, Proc. Natl. Acad. Sci. USA 96 (1999) 863-868] provides an in vivo means of selecting for and evaluating the strength of interaction between identical transmembrane alpha-helices. In the course of utilizing TOXCAT to study the architecture of a sodium channel hNa(V)1.5, an apparently strong dimerization of two of its putative transmembrane segments was revealed. Following random mutagenesis of these regions, several amino acids critical for the observed dimerizations were identified. In order to develop a more efficient means of isolating mutations which specifically disrupt dimerization of these transmembrane segments without affecting their membrane-targeting properties, we developed a modification to the original TOXCAT design in which the C-terminal maltose binding protein moiety is replaced by the beta-lactamase. We show that this assay system is capable of simultaneously monitoring the integrity of the chimeric protein, its membrane insertion activity, and the ability of the transmembrane segment under study to dimerize.

Amino Acid Sequence↗
PubMed1998

Clinical evaluation of a new in-line continuous blood gas monitor.

Two methodologies for obtaining accurate blood gas and electrolyte values during cardiopulmonary bypass (CPB) are traditional laboratory analyzers, which use an electrochemical technology, and continuous in-line monitoring systems, which use a fluorometric and/or spectrophotometric technology. The purpose of the present study was to evaluate the accuracy of a new continuous in-line monitor, the 3M CDI Blood Parameter Monitoring System 500, which provides continuous in-line measurements of pH, PCO2, PO2, potassium (K+), oxygen saturation, hematocrit, hemoglobin, and temperature, during partial or complete CPB. Study parameters included arterial pH, PCO2, PO2, and K+ values. Overall performance was analyzed by calculating the mean difference (expressed as the bias) between the CDI system 500 and the laboratory analyzer for each parameter. The accuracy of the arterial pH, PCO2, and K+ values provided by the CDI system 500 was then evaluated using target values established in the acceptable performance standards for laboratory analyzers from the Clinical Laboratory Improvement Act of 1988 (CLIA '88). The accuracy of the PO2 value provided by the CDI system 500 was evaluated using a target value of +/- 10% of the reference, or laboratory analyzer, value. A prospective multi-center trial was conducted following Institutional Review Board approval. A total of 75 cases was included in the analyses, with over 200 data points from 4 clinical locations. Results for pH, PCO2, and K+ were within the target values established by CLIA '88. pH bias was 0.00 +/- 0.02 pH units. PCO2 bias was -0.3 +/- 3.3 mm Hg. K+ bias was approximately +0.12 +/- 0.31 mmole/l. Results for PO2 were within 10% of the reference value. PO2 bias was 7.5 +/- 13.8 mm Hg. The results of this clinical trial show that the CDI System 500 continuous in-line monitoring system provides values that meet the accuracy standards for laboratory analyzers for arterial pH, PCO2, PO2, and K+.

Bias↗
PubMedDate not supplied

Design of a data-acquisition system for monitoring sleep organization in preterm infants.

A portable data-acquisition system suitable for long-term noninvasive monitoring of physiologic and behavioral variables in preterm infants is described. The system includes two video cameras, a video screen-splitter and amplifier, a time-lapse video recorder, a microphone, a force-responsive transducer, an analog signal conditioner, and two microcomputers. One microcomputer, located in the neonatal intensive care unit (NICU) acquires electrophysiologic signals and preprocesses data in real time, during a continuous 48-hour session. After each session, the data file is transferred by telephone line to the other microcomputer, located in a laboratory, for editing, reduction, display, and final analysis. This arrangement enables noninvasive and nonintrusive monitoring, which is crucial for long-term recording of sleep-wake state organization of preterm infants.

Computer Systems↗
PubMed1989

Intricacies of blood pressure measurement: reexamining the rituals.

Critical care clinicians are often frustrated when blood pressure values derived via direct monitoring methods (i.e., arterial lines) do not "correlate" with values obtained via indirect methods (e.g., auscultatory). Precious time has been spent attempting to troubleshoot monitoring systems and ascertain why these discrepancies exist. Greater insight into the intricacies of blood pressure monitoring reveals that both direct and indirect methods are subject to many external and physiologic influences that have the ability to significantly affect the value ultimately accepted as the "true" blood pressure. Direct blood pressure monitoring is influenced by normal physiologic changes in the pressure pulse configuration as it travels to the periphery, as well as by properties of the external monitoring system. Indirect monitoring is also influenced by a variety of factors, and may be unreliable in the very clinical situations where it is used the most. Finally, the relationship between blood pressure and blood flow, particularly in critically ill patients, suggests that it is unreasonable to expect that pressures obtained by direct monitoring methods will be the same as those derived by indirect methods that are flow dependent.

Blood Flow Velocity↗
PubMed2002

Development of a remote electrode system for monitoring the water content of materials inside a glass vial.

PURPOSE: This article explores the use of a remote electrode dielectric measurement system to monitor the water content of hydrated ovalbumin inside a glass vial. METHODS: The intrinsic dielectric properties of hydrated ovalbumin were characterized first using conventional parallel plate electrodes. The second stage was to simulate a remote electrode measurement by placing nonconductive, nondispersive polyethylene films between the sample and electrodes. Finally, a study on the dielectric measurement of ovalbumin contained in a 10 ml glass vial was undertaken with the electrodes external to the glass vial. RESULTS: The dielectric behavior of hydrated ovalbumin was characterized by charge transfer (i.e., protons) in the hydrogen bonded network of water molecules in the bulk sample. The mechanism was identified as an anomalous low-frequency dispersion and a dielectric loss peak (epsilon3). The dielectric relaxation time, tau3, of the epsilon3 dispersion was especially sensitive to water content. Moreover, a good correlation (R2 = 93%) was observed between relaxation times tau3 obtained from measurements using conventional parallel plate electrodes and the remote electrode system. CONCLUSIONS: Dielectric measurements using remote electrodes attached to a glass vial are therefore applicable for the in situ measurement of water content in materials. The application of this technology to the determination of the lyophilization end point is suggested.

Electrodes↗