Continuous Monitoring Technology Research Articles

Using Continuous Motion Monitoring Technology to Determine Patient’s Risk for Development of Pressure Ulcers

To perform initial validation of a continuous motion monitoring technology that can potentially be used as a risk assessment tool to determine risk for developing pressure ulcers (PUs). We have used the EverOn system (Earlysense LTD, Ramat Gan, Israel) as a bed movement and activity monitor. The EverOn is a contactless continuous measurement system based on a piezoelectric sensor that is placed under the patient's mattress. The study was a noninterventional study performed in 2 medical departments in 2 medical centers. Recorded movement data from enrolled patients were retrospectively analyzed, and patients were assigned a motion level score. Motion scores for the first night of hospitalization were correlated with the Norton scale as calculated per patient on admission. Overall, 116 patients were included in the study from the 2 sites. Motion score was significantly different between the PU risk groups as determined by the Norton scale (10.7 ± 6.2 for low, 5.4 ± 4.9 for intermediate, and 1.6 ± 3.2 for high risk; P < 0.001). Using the Norton scale as a gold standard to define high risk for developing PU (≤14), the sensitivity of the motion score was 85%, and the specificity was 93%. With regard to individual risk components, we found that activity, mobility, physical condition, and incontinence correlated highly with motion level. The high correlation between the EverOn motion score and the calculated Norton scale indicates the potential of this technology to serve as a risk assessment tool for the development of PUs.

Comparison of Leak-Detection Technologies for Continuous Monitoring of Subsea-Production Templates

Summary Subsea leakages from underwater production facilities may have significant environmental and economical consequences. There is a wide range of different technologies available for detection of subsea leakages, depending on the type of application and approach to leak detection. The two most common approaches to direct subsea-leak detection are inspection/surveying, where sensors are attached to mobile units such as remotely operated vehicles (ROVs), and continuous monitoring, where the sensors are permanently installed at the seabed. For the latter case, there are several different types of leak-detection technologies, depending on whether templates or pipelines are to be monitored. While most subsea facilities are monitored by flow-measurement devices that can typically detect leaks that are greater than a few percent of overall flow, this paper addresses direct methods of leak detection suitable for smaller leaks. The Norwegian Oil Industry Association (OLF) has initiated a series of projects on subsea-leak detection to obtain an overview of the different types of leak-detection systems available and to determine the practical applicability and functionality of these systems. An important issue in this regard is to test the leak-detection systems experimentally with both gas and oil leakages under realistic conditions. This paper presents results from comparative, experimental tests of five different leak-detection systems that are suitable for continuous monitoring of subsea templates with the goal of elucidating the strengths and limitations of the different detection principles.

Evaluation of artificial pancreas technology for continuous blood glucose monitoring in dogs

Artificial pancreas technology, involving "closed-loop" controls with real-time blood glucose monitoring, has been increasing in reliability as its potential for clinical use and application grows. One such device, based on this technology, is the STG-22 (Nikkiso Co., Ltd., Tokyo, Japan) artificial pancreas apparatus. In order to assess the reliability and accuracy of the device for measuring blood glucose, it is important to compare its readings to those obtained using a 'gold standard' method, such as the hexokinase method. Therefore, in the present study, canine blood [glucose] measurements using the STG-22 were compared to those obtained using a previously established commercial reagent, Quickauto-Neo GLU-HK. Furthermore, two different sample types (whole blood versus plasma constituent) were compared to determine which sample type results in more accurate and optimal readings with the STG-22. Given that the STG-22 was not primarily designed for canine blood samples, results for canine blood samples were not accurate. Measurements performed by the STG-22 with whole blood were significantly lower than reference [glucose] counterparts. Alternatively, an opposite trend was observed with plasma measurements that were significantly higher. A conversion format using the following formula, Hexokinase [glucose]=STG-22 [glucose]×1.407+1.532, was observed with canine samples in our study.

Multi-day pre-clinical demonstration of glucose/galactose binding protein-based fiber optic sensor

We report here the first pre-clinical demonstration of continuous glucose tracking by fluorophore-labeled and genetically engineered glucose/galactose binding protein (GGBP). Acrylodan-labeled GGBP was immobilized in a hydrogel matrix at the tip of a small diameter optical fiber contained in a stainless steel needle. The fiber optic biosensors were inserted subcutaneously into Yucatan and Yorkshire swine, and the sensor response to changing glucose levels was monitored at intervals over a 7-day period. Sensor mean percent error on day 7 was 16.4 ± 5.0% using a single daily reference blood glucose value to calibrate the sensor. The GGBP sensor's susceptibility to common interferents was tested in a well-plate system using human sera. No significant interference was observed from the tested interferents except for tetracycline at the drug's maximum plasma concentration. The robust performance of the GGBP-based fiber optic sensor in swine models and resistance to interferents indicates the potential of this technology for continuous glucose monitoring in humans.

Suboptimal H∞ hyperglycemia control on T1DM accounting biosignals of exercise and nocturnal hypoglycemia

AbstractThe availability of novel technologies for exogenous insulin release and continuous glucose monitoring have increased the possibilities of developing an artificial pancreas. This contribution tackles the design of a H∞‐based controller to manage glycemia in Type 1 diabetes mellitus (T1DM) under two scenarios: exercise and nocturnal hypoglycemia. Two biosignals are integrated to the blood glucose control problem: lactate is used in exercise scenario, while adrenaline releasing is used for nocturnal hypoglycemia. The effects of each scenario are represented by weighting transfer functions at the control design. Each weighting function accounts the effect of hepatic glucose production and defines separately the following relations: (a) from plasmatic glucose to lactate during exercise and (b) from plasmatic glucose to adrenaline during nocturnal hypoglycemia. Also, the controller is designed by adding a frequency restriction in control signal to incorporate frequency components by the pancreatic insulin release pattern in a healthy subject. A nonlinear physiological model, including Glucose–Insulin–Glucagon dynamics and counter‐regulatory effects, is used to show the time‐response of the closed‐loop including actuator dynamics and parametric changes. Copyright © 2011 John Wiley &amp; Sons, Ltd.

A fluorescence lifetime-based fibre-optic glucose sensor using glucose/galactose-binding protein

Alternative, non-electrochemistry-based technologies for continuous glucose monitoring are needed for eventual use in diabetes mellitus. As part of a programme investigating fluorescent glucose sensors, we have developed fibre-optic biosensors using glucose/galactose binding protein (GBP) labelled with the environmentally sensitive fluorophore, Badan. GBP-Badan was attached via an oligohistidine-tag to the surface of Ni-nitrilotriacetic acid (NTA)-functionalized agarose or polystyrene beads. Fluorescence lifetime increased in response to glucose, observed by fluorescence lifetime imaging microscopy of the GBP-Badan-beads. Either GBP-Badan agarose or polystyrene beads were loaded into a porous chamber at the end of a multimode optical fibre. Fluorescence lifetime responses were recorded using pulsed laser excitation, high speed photodiode detection and time-correlated single-photon counting. The maximal response was at 100 mM glucose with an apparent K(d) of 13 mM (agarose) and 20 mM (polystyrene), and good working-day stability was demonstrated. We conclude that fluorescence lifetime fibre-optic glucose sensors based on GBP-Badan are suitable for development as clinical glucose monitors.

Technologies for Continuous Glucose Monitoring: Current Problems and Future Promises

Devices for continuous glucose monitoring (CGM) are currently a major focus of research in the area of diabetes management. It is envisioned that such devices will have the ability to alert a diabetes patient (or the parent or medical care giver of a diabetes patient) of impending hypoglycemic/hyperglycemic events and thereby enable the patient to avoid extreme hypoglycemic/hyperglycemic excursions as well as minimize deviations outside the normal glucose range, thus preventing both life-threatening events and the debilitating complications associated with diabetes. It is anticipated that CGM devices will utilize constant feedback of analytical information from a glucose sensor to activate an insulin delivery pump, thereby ultimately realizing the concept of an artificial pancreas. Depending on whether the CGM device penetrates/breaks the skin and/or the sample is measured extracorporeally, these devices can be categorized as totally invasive, minimally invasive, and noninvasive. In addition, CGM devices are further classified according to the transduction mechanisms used for glucose sensing (i.e., electrochemical, optical, and piezoelectric). However, at present, most of these technologies are plagued by a variety of issues that affect their accuracy and long-term performance. This article presents a critical comparison of existing CGM technologies, highlighting critical issues of device accuracy, foreign body response, calibration, and miniaturization. An outlook on future developments with an emphasis on long-term reliability and performance is also presented.

ICalm: Wearable Sensor and Network Architecture for Wirelessly Communicating and Logging Autonomic Activity

Widespread use of affective sensing in healthcare applications has been limited due to several practical factors, such as lack of comfortable wearable sensors, lack of wireless standards, and lack of low-power affordable hardware. In this paper, we present a new low-cost, low-power wireless sensor platform implemented using the IEEE 802.15.4 wireless standard, and describe the design of compact wearable sensors for long-term measurement of electrodermal activity, temperature, motor activity, and photoplethysmography. We also illustrate the use of this new technology for continuous long-term monitoring of autonomic nervous system and motion data from active infants, children, and adults. We describe several new applications enabled by this system, discuss two specific wearable designs for the wrist and foot, and present sample data.

Bio-inspired self powered nervous system for civil structures

Globally, civil infrastructures are deteriorating at an alarming rate caused by overuse, overloading, aging, damage or failure due to natural or man-made hazards. With such a vast network of deteriorating infrastructure, there is a growing interest in continuous monitoring technologies. In order to provide a true distributed sensor and control system for civil structures, we are developing a Structural Nervous System that mimics key attributes of a human nervous system. This nervous system is made up of building blocks that are designed based on mechanoreceptors as a fundamentally new approach for the development of a structural health monitoring and diagnostic system that utilizes the recently developed piezo-fibers capable of sensing and actuation. In particular, our research has been focused on producing a sensory nervous system for civil structures by using piezo-fibers as sensory receptors, nerve fibers, neuronal pools, and spinocervical tract to the nodal and central processing units. This paper presents up to date results of our research, including the design and analysis of the structural nervous system.

Physiological and Medical Monitoring for En Route Care of Combat Casualties

Most prehospital medical interventions during civilian and military trauma casualty transport fail to utilize advanced decision-support systems for treatment and delivery of medical interventions, particularly intravenous fluids and oxygen. Current treatment protocols are usually based on standard vital signs (eg, blood pressure, arterial oxygen saturation) which have proven to be of limited value in detecting the need to implement an intervention before cardiovascular collapse. A primary objective of the US Army combat casualty care research program is to reduce mortality and morbidity during casualty transport from the battlefield through advanced development of a semiautomated decision-support capability for closed-loop resuscitation and oxygen delivery. To accomplish this goal, the Trauma Informatics Research Team at the US Army Institute of Surgical Research has developed two models for evidence-based decision support 1) a trauma patient database for capture and analysis of prehospital vital signs for identification of early, novel physiologic measurements that could improve the control of closed-loop systems in trauma patients; and, 2) a human experimental model of central hypovolemia using lower body negative pressure to improve the understanding and identification of physiologic signals for advancing closed-loop capabilities with simulated hemodynamic responses to hemorrhage. In the trauma patient database and lower body negative pressure studies, traditional vital sign measurements such as systolic blood pressure and oxygen saturation fail to predict mortality or indicate the need for life saving interventions or reductions in central blood volume until after the onset of cardiovascular collapse. We have evidence from preliminary analyses, however, that indicators of reduced central blood volume in the presence of stable vital signs include 1) reductions in pulse pressure; 2) changes in indices of autonomic balance derived from calculation of heart period variability (ie, linear and non-linear analyses of R-R intervals); and 3) reductions in tissue oxygenation. We propose that derived indices based on currently available technology for continuous monitoring of specific hemodynamic, autonomic, and/or metabolic responses could provide earlier recognition of hemorrhage than current standard vital signs and allow intervention before the onset of circulatory shock. Because of this, such indices could provide improved feedback for closed-loop control of patient resuscitation and oxygen delivery. These technological advances could prove instrumental in advancing decision-support capabilities for prehospital trauma care during transport to higher levels of care in both the military and civilian environments.

Acute normovolemic hemodilution, intraoperative cell salvage and PulseCO hemodynamic monitoring in a Jehovah’s Witness with placenta percreta

A Jehovah's Witness who had had four previous cesarean deliveries was referred to our institution for management of a complete placenta previa at 34 weeks of gestation. A subsequent ultrasound scan was suggestive of placenta percreta with bladder involvement. After erythropoietin and iron supplementation, cesarean hysterectomy was performed. Using PulseCO technology for continuous hemodynamic monitoring, preoperative acute normovolemic hemodilution and intraoperative cell salvage were used resulting in a successful cesarean hysterectomy with a 5500-mL estimated blood loss. The PulseCO system provides continuous, real-time hemodynamic data by applying pulse power analysis to the arterial pressure waveform. A bolus of oxytocin given after delivery produced profound hypotension, the hemodynamics of which were elucidated with the PulseCO system. To our knowledge, the combined use of acute normovolemic hemodilution, intraoperative cell salvage and PulseCO hemodynamic monitoring for cesarean hysterectomy has not been reported previously. These techniques may be particularly useful in managing patients who refuse blood products and/or in whom the baseline hemoglobin is suboptimal.

Implementation of an electronic nose for continuous odour monitoring in a poultry shed

Continuous odour monitoring technologies are necessary to understand the complex odour-generating mechanisms within poultry housing as well as to identify strategies to reduce the impact of odour emissions on local communities. To evaluate electronic nose (EN) technologies for continuously assessing odour concentration in poultry housing, a mobile laboratory containing an electronic nose and an associated sample delivery system was deployed to a commercial poultry farm and tested over a broiler production cycle. The results demonstrated that it was possible to develop a model to allow an electronic nose to provide a semi-continuous measurement of odour concentrations. The electronic nose was also able to demonstrate the influence of shed conditions on odour emissions.

Novel Online Sensor Technology for Continuous Monitoring of Milk Coagulation and Whey Separation in Cheesemaking

The cheese industry has continually sought a robust method to monitor milk coagulation. Measurement of whey separation is also critical to control cheese moisture content, which affects quality. The objective of this study was to demonstrate that an online optical sensor detecting light backscatter in a vat could be applied to monitor both coagulation and syneresis during cheesemaking. A prototype sensor having a large field of view (LFV) relative to curd particle size was constructed. Temperature, cutting time, and calcium chloride addition were varied to evaluate the response of the sensor over a wide range of coagulation and syneresis rates. The LFV sensor response was related to casein micelle aggregation and curd firming during coagulation and to changes in curd moisture and whey fat contents during syneresis. The LFV sensor has potential as an online, continuous sensor technology for monitoring both coagulation and syneresis during cheesemaking.

Lab-on-a-Chip Technology for Continuous Glucose Monitoring

The demand for continuous glucose monitoring systems is greater than ever. The microelectromechanical systems (MEMS) approach has the advantage of being relatively easy to upscale to a commercial level; the preferred MEMS technique would be to run several detectors at once and, through the improved statistics, get a both more accurate and more reliable device than is currently available. Lab-on-a-chip technology may be seen as a further development of MEMS technology for analytical sensors. Lab-on-a-chip systems may be used to obtain improvements on several important characteristics of a sensor system: remove or decrease cross-sensitivity, improve sensor stability, improve accuracy, and/or improve response time compared to similar laboratory-equipment methods.

Characterising phosphorus transfers in rural catchments using a continuous bank-side analyser

Abstract. A six-month series of high-resolution synchronous stream discharge and total phosphorus (TP) concentration data is presented from a 5 km2 agricultural catchment in the Lough Neagh basin, Northern Ireland. The data are hourly averages of 10-minute measurements using a new bankside, automatic, continuous monitoring technology. Three TP transfer "event-types" occur in this catchment: (1) chronic, storm independent transfers; (2) acute, storm dependent transfers; (3) acute, storm independent transfers. Event-type 2 transferred over 90% of the total 279 kg TP load in 39% of the total period; it corresponded to diffuse transfers from agricultural soils. Event-types 1 and 3, however, maintained the river in a highly eutrophic state between storm events and were characteristic of point source pollution, despite there being no major industrial or municipal point sources. Managing P transfers at the catchment scale requires a robust monitoring technology to differentiate between dynamic, multiple sources and associated event types and so enable a reliable assessment of the performance of mitigation measures, monitored at catchment outlets. The synchronous and continuous TP and discharge data series generated in this study demonstrate how this is possible.

Design of a biomimetic-based monitoring and diagnostic system for civil structures

Recent high intensity natural events such as hurricanes, tsunamis, and earthquakes have introduced new challenges for the design, maintenance, and sustainability of civil structures. Globally, civil infrastructures are deteriorating at an alarming rate caused by overuse, overloading, aging, damage or failure due to natural or man-made hazards. With such a vast network of deteriorating infrastructure, there is a growing interest in continuous monitoring technologies. In order to provide an information data transfer mechanism that integrates output of an embedded, distributed sensory network and the control system in civil structures, this paper describes design and development of a Structural Nervous System that mimics key attributes of the human nervous system. This biomimetic-based innovative idea for the design of a self-powered structural monitoring and diagnostic system utilises a novel, non-living plant protein (forisome) for sensing and information transfer. The overall nervous system design and preliminary experimental data on forisomes are presented in this paper.

Improved Glycemic Control in Poorly Controlled Patients with Type 1 Diabetes Using Real-Time Continuous Glucose Monitoring

Intensive self-management with frequent self-monitoring of blood glucose (SMBG) is important in type 1 diabetes to achieve good metabolic control (1–3). Nevertheless, many patients still experience episodes of unrecognized hypo- and hyperglycemia (4). Novel technologies for continuous glucose monitoring (CGM) that provide information about glucose excursions are now available. Previous studies reported the benefits of retrospective evaluation of CGM data (5–11), but few assessed effects on glycemic control (5,12–14), and only one showed improvements compared with SMBG (14). We evaluated the effect of a new real-time glucose monitor on glycemic control in patients with poorly controlled type 1 diabetes. The device, Guardian RT (Medtronic MiniMed, Northridge, CA), allows users to see glucose readings and set hypo- and hyperglycemic alarms and provides trend information on changing glucose values. The study included 81 children (median age 14.4 years [range 8.0–18.9]) and 81 adults (age 39.1 years [19.0–59.5]) with stable type 1 diabetes. All had adhered to intensified insulin treatment (continuous subcutaneous insulin infusion, n = 78; multiple daily injection, n = 84) but had HbA1c (A1C) levels ≥8.1%. Informed consent was obtained from patients regularly attending the eight participating centers. Subjects were randomly assigned 1:1:1 for 3 months to Guardian RT continuously (arm 1) or biweekly for 3-day periods every 2 weeks (arm 2) or to continue conventional SMBG (control). Treatment adjustments made by physicians and patients were based on SMBG profiles in control subjects and on real-time glucose profiles in arms 1 and 2. Patients were instructed to perform confirmatory SMBG measurements before therapeutical interventions or corrective action if hypo- or hyperglycemic alarms or symptoms occurred. …

The Development of Minimally Invasive Continuous Metabolic Monitoring Technologies in the U.S. Army TMM Research Program

The Technologies for Metabolic Monitoring and Julia Weaver Fund Research Program (TMM) promotes the development of minimally invasive, innovative technologies for the monitoring and assessment of metabolic changes that are important to the management of diabetes. This program also promotes the advancement of biological monitoring technologies for healthy individuals operating in extreme environments, such as soldiers and astronauts. These technologies have focused on measurements of analytes in interstitial fluids and functional outcomes related to glucose regulation. TMM investigators have advanced new sensing methods and are working to overcome technological barriers to long-term implants. This paper reviews the current goals, research areas, and future direction of the program.

Continuous monitoring of water loading of trees and canopy rainfall interception using the strain gauge method

A non-destructive continuous monitoring technology was developed for documenting diurnal changes in branch weight using resistance strain gauges. The capacity of rainfall interception by the canopy can be directly measured by attaching strain gauges to the branch. The amount of water loaded in tree reaches a maximum in the early morning, and a minimum in the afternoon. Thus, the branch is the heaviest in the early morning, and the lightest in the afternoon. Differences between the weight in the morning and in the afternoon can represent as the daily change in water loading of the branch. The branch can be considered as an elastic cantilever in response to the changes in weight of water carried by the branchlets and leaves, and the changes in strain are caused by the change in the bending stress of branch. Thus, the branch increases its weight when rainfall interception occurs, that also changes the stress of branch. The technique reported in this paper will provide an effective approach to investigating biological biometrics.

Ophthalmic glucose sensing: a novel monosaccharide sensing disposable and colorless contact lens.

We have developed a technology for continuous tear glucose monitoring, and therefore potentially blood glucose monitoring, using a daily use, disposable contact lens embedded with sugar-sensing boronic acid containing fluorophores. The novelty of our approach is two fold. Firstly, the notion of sensing extremely low glucose concentrations in tears by our approach, and secondly, the unique compatibility of our new probes with the internal environment of the disposable, off-the-shelf, contact lenses, chosen because the physiological compatibility of disposable plastic contact lenses has already been assessed and optimized with regard to vision correction, size and oxygen/analyte permeability. Our findings show that our approach is indeed suitable for the continuous monitoring of tear glucose levels in the concentration range (50-500 microM), which track blood glucose levels which are approximately 5-10 fold higher. We believe our approach offers unique opportunities for non-invasive continuous glucose monitoring for diabetics, especially since many have eye disorders and require vision correction by either contact lenses or glasses, which is thought to be due to glycation of protein in blood vessels.