The need for continuous blood glucose monitoring in the intensive care unit

Development and clinical trial of a smartphone-based colorimetric detection system for self-monitoring of blood glucose

Blood glucose measurements help to guide insulin therapy, thus reducing disease severities, secondary complications, and related mortalities. Efforts are underway to allow diabetes patients to experience a more convenient way to measure blood glucose and consequently increase their adherence to regular self-monitoring of blood glucose (SMBG). This study demonstrated a new SMBG system that integrated all components of a glucometer via a smartphone's optical sensing module to detect the colorimetric blood strip and obtains the blood glucose concentration with calculations performed by an application install in the smartphone. To validate the accuracy and applicability of the new SMBG system regarding the ISO15197:2013 accuracy criteria and patient requirements, a clinical trial and usability survey involving participants from different age groups were conducted in collaboration with the China Medical University, where enrolled 120 diabetic patients were asked to operate the new SMBG system to measure their blood glucose concentration, and feedback was obtained from their user experience. The results showed that three different reagent system lots fulfilled the accuracy requirements with values of 97.4-97.5% , and all of the data were within zones A and B of the consensus error grid, which satisfies the ISO 15197:2013 requirement. The usability survey showed that 97.5% of the participants found the operations convenient, and 100% found the design easy for carrying. This new system could lead to improvements in blood glucose monitoring by people with diabetes, and thus, better management of the disease.

Insulin-Based Infusion System: Preliminary Study

BACKGROUND

Optimal glucose control has been shown to be useful in critical care as well as in other settings. Glucose concentrations in patients admitted to critical care are characterized by marked variability and hypoglycemia due to inadequate sensing and treatment technologies.

METHODS

The insulin balanced infusion system (IBIS) is a closed-loop system that uses a system controller, two syringe pumps, and capillary glucose sensor intravenously infusing regular insulin and/or dextrose. The IBIS performance was evaluated in terms of glucose stability in response to various conditions in subjects with type 1 and insulin requiring type 2 diabetes mellitus (n = 15) with frequent intermittent capillary measurements, entered into the system and an adaptive algorithm adjusting the treatment modalities without other nursing intervention.

RESULTS

Target glucose concentrations (80-125 mg/dl) were achieved from hyperglycemic levels in 2.49 hours in the first study with mean and standard deviation of 105.2 mg/dl and 11.5 mg/dl, respectively.

CONCLUSION

Preliminary studies using a prototype closed-loop glucose control system for critical care produced noticeable results. Improvements were initiated within the system and further studies performed.

Insulin-Based Infusion System: Advancing the Development

BACKGROUND

Deviations in glucose control in critical care have been shown to increase mortality and morbidity. However, optimal glucose control through present technologies has shown to be a challenge. The insulin balanced infusion system (IBIS) is a new and emerging technology.

METHODS

The closed loop system was tested in a stress trial to evaluate glucose stability in response to various conditions in nonrandomized people with type 1 diabetes mellitus (n=12). The prototype used in this trial was based on intermittent capillary measurements.

RESULTS

Induced stresses in the study using unpredicted stimuli of intravenous or oral glucose and intravenous insulin boluses, was contained with glucose remaining in target 43.8% of the time. Mean increase in glucose concentration after glucose load was 17.4 mg/dl; after insulin bolus, no hypoglycemia (blood glucose less than 70 mg/dl) occurred.

CONCLUSION

The use of IBIS proved safe and feasible under a wide range of conditions. The sensing and stress response of the IBIS demonstrated noticeable features.

Design, fabrication, and feasibility analysis of a colorimetric detection system with a smartphone for self-monitoring blood glucose

Maintaining appropriate insulin levels is very important for diabetes patients. Effective monitoring of blood glucose can aid in maintaining the body's insulin level, and thus reduce disease severities, secondary complications, and related mortalities. However, existing blood glucose measurement devices are inconvenient to carry and involve complex procedures, reducing the willingness of diabetes patients to regularly measure blood glucose. We aim to provide a rapid, convenient, and portable meter for diabetes patients. We introduce an integrated blood glucose detection device (IBGDD) that has no electronic component and uses the optical sensing module of a smartphone to inspect colorimetric blood strips. To demonstrate accuracy conformance of the developed device to the ISO 15197:2013 standard for blood glucose measurement, 20 diabetes mellitus patients used the IBGDD with smartphones to measure their blood glucose level. The measurement results revealed an accuracy of 100%, completely satisfying the requirements of the ISO 15197:2013 standard. Overall, our specially designed IBGDD with a smartphone could achieve high accuracy and convenient usage for the measurement of blood glucose concentration. Furthermore, the device is highly portable and simple to operate. This contributes toward achieving self-monitoring of blood glucose by diabetes patients and improved mobile health in the future.

Vascular Glucose Sensor Symposium: Continuous Glucose Monitoring Systems (CGMS) for Hospitalized and Ambulatory Patients at Risk for Hyperglycemia, Hypoglycemia, and Glycemic Variability

Hyperglycemia, hypoglycemia, and glycemic variability have been associated with increased morbidity, mortality, length of stay, and cost in a variety of critical care and non-critical care patient populations in the hospital. The results from prospective randomized clinical trials designed to determine the risks and benefits of intensive insulin therapy and tight glycemic control have been confusing; and at times conflicting. The limitations of point-of-care blood glucose (BG) monitoring in the hospital highlight the great clinical need for an automated real-time continuous glucose monitoring system (CGMS) that can accurately measure the concentration of glucose every few minutes. Automation and standardization of the glucose measurement process have the potential to significantly improve BG control, clinical outcome, safety and cost.

Current state of glycemic control in critically ill subjects in a general intensive care unit

Critically ill patients are predisposed to stress-induced hyperglycemia. Recent evidence suggests that uncontrolled hyperglycemia is associated with poor outcomes within the population of surgical and medical intensive care units. We retrospectively audited our practice in the management of hyperglycemia in the critically ill, in order to identify reasons and periods of time that deviations in blood glucose control are most likely, and to make recommendations on how to improve this. Our study showed poor compliance with the current recommendations for glycemic control in the critically ill and highlighted the need for a successful protocol for glycemic control in our institution. That should be carefully coordinated with the level of nutritional support and metabolic status of the acutely ill patient.

Prediction of glucose concentration in post-cardiothoracic surgery patients using continuous glucose monitoring

OBJECTIVE

This study evaluated the predictive capability of simple linear extrapolation of continuous glucose data in postsurgical patients undergoing intensive care.

METHODS

Twenty patients, both with or without an established diagnosis of diabetes mellitus, scheduled to undergo cardiothoracic surgery were included. Glucose was continuously monitored in the intensive care unit with a microdialysis-based subcutaneous glucose monitoring system. The prediction horizon (PH) with respect to a given glucose reading was calculated by extrapolating the linear trend of the glucose signal and subjected to both analytical and clinical assessment (by calculation of the average duration of consecutive positive and negative glucose signal trends, the root mean squared error [RMSE], and by insulin titration error grid [ITEG] analysis, respectively).

RESULTS

In total, 609 h of continuous glucose data from 17 patients were analyzed. The average duration of consecutive positive and negative glucose signal trends was 7.97 (3.99-19.98) min (median, interquartile range). An increase in the RMSE of 0.5 mmol/L (9 mg/dL) was associated with a PH of 37 min. A strong increase in the number of data points in the unacceptable violation zone of the ITEG was associated with a PH of approximately 20 min.

CONCLUSIONS

Our data provide evidence that simple linear extrapolation of glucose trend information obtained by continuous glucose monitoring can be used to predict the course of glycemia in critically ill patients for up to 20-30 min. This "glimpse into the future" can be used to proactively prevent the occurrence of adverse events.

Automated blood sampling and glucose sensing in critical care settings

BACKGROUND

Tight glycemic control (TGC) studies in intensive care units (ICU) have shown substantial improvements in clinical outcomes. However, implementation of TGC in ICU practice is partly constrained by the lack of automated continuous blood glucose monitoring systems that can facilitate clinically accurate feedback of glycemic data. The aim of this work is to develop a portable automated blood sampling system for integration with a glucose sensor for use in critical care settings.

METHODS

clinical prototypes for glucose sensing in blood were developed based on two distinct technologies: mid-infrared laser absorption spectroscopy and electrochemistry. Concurrently, an automated peripheral venous blood sampling system was developed for integration with the glucose sensing system.

RESULTS

The glucose sensing prototypes were validated clinically with various biological samples in a continuous mode. A customized micropump was employed in conjunction with a novel peripheral venous catheter system to automatically sample blood from the subject's forearm. Microvolumes of blood were sampled in continuous and intermittent modes at clinically relevant user-defined frequencies. The clinical feasibility of blood sampling, along with continuous glucose sensing, was demonstrated.

CONCLUSION

Cascade's automated peripheral venous blood sampling system, in combination with a flow-through glucose sensor system, offers several advantages over current state-of-the-art systems. This includes the potential for significantly improved workflow in the ICU, minimal discomfort to the patient, and accurate glucose measurement in whole blood, thus helping achieve tight glycemic control.

An analysis: hyperglycemic intensive care patients need continuous glucose monitoring-easier said than done

Experts and agencies increasingly advocate tight glycemic control (TGC) using intensive intravenous insulin therapy in critically ill patients. Questions remain about the "best" glucose goal, the universal benefit of TGC in the heterogeneous adult intensive care unit (ICU) population, and concerns about the underrecognized incidence of hypoglycemia and its neuropsychological sequelae. TGC is time-consuming for ICU staff, and pathophysiologic, technical, and personnel factors impact the accuracy of point-of-care glucose monitoring. TGC in the ICU requires safe, accurate, robust, rapid, and continuous glucose measurements (CGM) that lack interference from drugs or other substances. Establishment of reliable CGM may provide the foundation for a closed loop, microprocessed system resulting in an artificial islet cell. This commentary focuses on reports from two respected groups on the potential use of CGM devices in the critically ill. It emphasizes the challenges of applying this technology in the ICU and looks to future refinements to address them.

Analysis of algorithms for intensive care unit blood glucose control

Intensive care unit (ICU) blood glucose control algorithms were reviewed and analyzed in the context of linear systems theory and classical feedback control algorithms. Closed-loop performance was illustrated by applying the algorithms in simulation studies using an in silico model of an ICU patient. Steady-state and dynamic input-output analysis was used to provide insight about controller design and potential closed-loop performance. The proportional-integral-derivative, columnar insulin dosing (CID, Glucommander-like), and glucose regulation for intensive care patients (GRIP) algorithms were shown to have similar features and performance. The CID strategy is a time-varying proportional-only controller (no integral action), whereas the GRIP algorithm is a nonlinear controller with integral action. A minor modification to the GRIP algorithm was suggested to improve the closed-loop performance. Recommendations were made to guide control theorists on important ICU control topics worthy of further study.