Microcirculation and its relation to continuous subcutaneous glucose sensor accuracy in cardiac surgery patients in the intensive care unit

[Position statement: surgery and diabetes mellitus (Update 2023)]

This position statement reflects the perspective of the Austrian Diabetes Association concerning the perioperative management of people with diabetes mellitus based on the available scientific evidence. The paper covers necessary preoperative examinations from an internal/diabetological point of view as well as the perioperative metabolic control by means of oral antihyperglycemic and/or insulin therapy.

Changes in Accuracy of Continuous Glucose Monitoring Using Dexcom G4 Platinum Over the Course of Moderate Intensity Aerobic Exercise in Type 1 Diabetes

Continuous glucose monitoring (CGM) systems help diabetes management in patients with type 1 diabetes (T1D) but could have lower accuracy during exercise. We aim to evaluate the dynamics of CGM accuracy during exercise in patients with T1D. Secondary analysis of data was carried out on 22 patients with T1D (glycated hemoglobin [HbA_1c]: 7.3% ± 1.0%, diabetes duration: 23 ± 13 years), who did three exercise sessions (45 min at 60% VO_2max on an ergocycle, 3 h postmeal) with paired Dexcom G4 Platinum, and capillary glucose values that were collected every 5 min. Dexcom accuracy was evaluated using sensor bias (SB) and absolute relative difference (ARD). For dynamics of SB analysis, data pairs following hypoglycemia correction were excluded. The analyzed data included 792 pairs (594 during 66 exercise sessions, 198 at rest before exercise). Median ARD was 8.44 (5.35-12.13)% at rest and increased to 16.77 (10.75-26.72)% during exercise (P < 0.001). During exercise, mean SB values evolved from T0 minutes = 5.95 ± 16.04 mg/dL (exercise start); T5 = 9.55 ± 16.40; T10 = 13.51 ± 18.02; T15 = 15.32 ± 20.36; T20 = 17.30 ± 18.92; T25 = 19.46 ± 17.48; T30 = 21.08 ± 19.64; T35 = 19.10 ± 20.36; T40 = 19.82 ± 20.18; and T45 = 18.02 ± 20.90 (exercise end). CGM overestimated capillary at a mean SB of 14.23 ± 16.76 mg/dL over the whole exercise session. CGM accuracy decreased during moderate aerobic exercise as previously described. However, the trend to overestimate capillary glucose was maintained at relatively stable values within 15 min of exercise initiation, which could help patients in their clinical decisions. Similar analyses would be needed for other types of exercise.

Perioperative Characteristics of the Accuracy of Subcutaneous Continuous Glucose Monitoring: Pilot Study in Neurosurgery and Cardiac Surgery

BACKGROUND

The aim of this study was to elucidate the characteristics of accuracy of subcutaneous continuous glucose monitoring (SCGM) in the perioperative period for neurosurgical and cardiac surgery patients.

METHODS

Forty-five subjects, including healthy volunteers (n = 15), neurosurgical patients (n = 15), and cardiac surgery patients (n = 15), were enrolled. A subcutaneous sensor of the MiniMed™ 620G SCGM system was inserted into the upper arm. On the day after sensor insertion, SCGM data and blood glucose data were collected simultaneously and compared. In cardiac surgery patients, data were continuously collected on postoperative day (POD) 1 and POD 3. Clarke error grid analysis and Bland-Altman analysis were performed to assess the accuracy of SCGM.

RESULTS

Clarke error grid analysis showed clinical acceptance of the SCGM system with 82.7% and 86.8% of the data being within zone A for healthy volunteers and neurosurgical patients, respectively. Mean biases were -2.1 mg/dL in healthy volunteers and -8.3 mg/dL in neurosurgical patients. In cardiac surgery, although Clarke error grid analysis showed clinical acceptance, 65.3% of the data were within zone A and mean bias was -23.5 mg/dL. Changes in accuracy of SCGM in individuals occurred during cardiopulmonary bypass (CPB), and SCGM tended to show a lower glucose level. On POD 1 and POD 3, the accuracy improved, and 85.0% and 86.3% of the data were within zone A.

CONCLUSIONS

Although the accuracy of the SCGM system was clinically acceptable in the perioperative period, sensor accuracy was affected by CPB and showed lower glucose levels.

Glucose Management during Insulinoma Resection Using Real-Time Subcutaneous Continuous Glucose Monitoring

Insulinoma is a rare neuroendocrine tumor that causes hypoglycemia due to unregulated insulin secretion. Blood glucose management during insulinoma resection is therefore challenging. We present a case in which real-time subcutaneous continuous glucose monitoring (SCGM) in combination with intermittent blood glucose measurement was used for glycemic control during surgery for insulinoma resection. The SCGM system showed the trends and peak of interstitial glucose in response to glucose loading and the change of interstitial glucose before and after insulinoma resection. These data were helpful for adjusting the glucose infusion; therefore, we think that an SCGM system as a supportive device for glucose monitoring may be useful for glucose management during surgery.

A prolonged run-in period of standard subcutaneous microdialysis ameliorates quality of interstitial glucose signal in patients after major cardiac surgery

We evaluated a standard subcutaneous microdialysis technique for glucose monitoring in two critically ill patient populations and tested whether a prolonged run-in period improves the quality of the interstitial glucose signal. 20 surgical patients after major cardiac surgery (APACHE II score: 10.1 ± 3.2) and 10 medical patients with severe sepsis (APACHE II score: 31.1 ± 4.3) were included in this investigation. A microdialysis catheter was inserted in the subcutaneous adipose tissue of the abdominal region. Interstitial fluid and arterial blood were sampled in hourly intervals to analyse glucose concentrations. Subcutaneous adipose tissue glucose was prospectively calibrated to reference arterial blood either at hour 1 or at hour 6. Median absolute relative difference of glucose (MARD), calibrated at hour 6 (6.2 (2.6; 12.4) %) versus hour 1 (9.9 (4.2; 17.9) %) after catheter insertion indicated a significant improvement in signal quality in patients after major cardiac surgery (p < 0.001). Prolonged run-in period revealed no significant improvement in patients with severe sepsis, but the number of extreme deviations from the blood plasma values could be reduced. Improved concurrence of glucose readings via a 6-hour run-in period could only be achieved in patients after major cardiac surgery.

Accuracy and reliability of a subcutaneous continuous glucose monitoring device in critically ill patients

Subcutaneous continuous glucose monitoring (CGM) may have benefits in achieving glycemic control in critically ill patients. The aim of this study was to assess the accuracy and reliability of the FreeStyle Navigator I in critically ill patients and to assess patient related factors influencing the accuracy and reliability. This study is a retrospective analysis of data from a randomized controlled trial conducted in a 20-bed mixed intensive care unit. Analytical accuracy, clinical accuracy and reliability were assessed against arterial blood glucose samples as reference. Assessment was according to recent consensus recommendations with median absolute relative difference (median ARD), Bland-Altman plots, the ISO system accuracy standards (ISO 15197:2013) and Clarke error grid analysis (CEG). We analyzed 2840 paired measurements from 155 critically ill patients. The median ARD of all paired values was 13.3 [6.9-22.1]%. The median ARD was significantly higher in both the hypoglycemic and the hyperglycemic range (32.4 [12.1-53.4]% and 18.7 [10.7-28.3]% respectively, p < 0.001). The Bland-Altman analysis showed a mean bias of - 0.82 mmol/L with a lower limit of agreement (LOA) of - 3.88 mmol/L and an upper LOA of 2.24 mmol/L. A total of 1626 (57.3%) values met the ISO-2013, standards and 1,334 (47%) CGM values were within 12.5% from the reference value. CEG: 71.0% zone A, 25.8% zone B, 0.5% zone C, 2.5% zone D, 0.3% zone E. The median overall real-time data display time was 94.0 ± 14.9% and in 23% of the patients, the sensor measured < 95% of the time. Additionally, data gaps longer than 30 min were found in 48% of the patients. The analytical accuracy of the FreeStyle Navigator I in critically ill patients was suboptimal. Furthermore, the clinical accuracy, did not meet the required standards. The reliability was satisfactory, however, in almost a quarter of the patients the realtime data display was < 95%. The accuracy was considerably and significantly lower in hyper- and hypoglycemic ranges.

Glucose Variability Based on Continuous Glucose Monitoring Assessment Is Associated with Postoperative Complications after Cardiovascular Surgery

PURPOSE

This purpose of this prospective study was to use a continuous glucose monitoring (CGM) system to evaluate the suitability of our institution's glucose management protocol after cardiovascular surgery and to clarify the impact of glycemic variability on postoperative complications.

METHODS

In all, 76 patients who underwent elective cardiovascular surgery and were monitored perioperatively using a CGM system were evaluated. Postoperative glucose management consisted of continuous intravenous insulin infusion (CIII) in the intensive care unit, and subcutaneous insulin injections (SQII) after oral food intake started. CIII and subcutaneous injections were initiated when blood glucose level exceeded 150 mg/dL. CGM data were used to analyze perioperative glycemic variability and association with postoperative complications.

RESULTS

Target glucose levels (71-180 mg/dL) were achieved during 97.1 ± 5.5% and 86.4 ± 19.0% of the continuous insulin infusion and subcutaneous injection periods, respectively. Major postoperative complications were surgical site infections, found in 6.6% of total patients, and atrial fibrillation, found in 44% of patients with off-pump coronary artery bypass grafting. High glycemic variability during SQII was associated with increased risk for both complications.

CONCLUSION

Data analysis revealed that our glucose management protocol during CIII was adequate. However, the management protocol during SQII required improvement.

Safety of using real-time sensor glucose values for treatment decisions in adolescents with poorly controlled type 1 diabetes mellitus: a pilot study

BACKGROUND

This study explored the safety of using real-time sensor glucose (SG) data for treatment decisions in adolescents with poorly controlled type 1 diabetes.

METHODS

Ten adolescents with type 1 diabetes, HbA1c ≥9% on insulin pumps were admitted to the clinical research center and a continuous glucose sensor was inserted. Plasma glucose was measured at least hourly using Yellow Springs Instrument's (YSI) glucose analyzer. Starting at dinner, SG rather than YSI was used for treatment decisions unless YSI was <70 mg/dL (<3.9 mmol/L) or specific criteria indicating SG and YSI were very discordant were met. Participants were discharged after lunch the next day.

RESULTS

Ten participants (seven males; 15.2-17.8 year old) completed the study. The range of differences between high glucose correction doses using SG vs YSI for calculations was -2 (SG < YSI dose) to +1 (SG > YSI dose); this difference was two units in only 2 of 23 correction doses given (all SG < YSI dose). There were five episodes of mild hypoglycemia in two patients, two of which occurred after using SG for dose calculations. There was no severe hypoglycemia and no YSI glucose >350 mg/dL (19.4 mmol/L). Mean (±SE) pre- and postmeal YSI glucose were 163 ± 11 and 183 ± 12 mg/dL (9.1 ± 0.6 and 10.2 ± 0.7 mmol/L), respectively.

CONCLUSION

Use of real-time continuous glucose monitoring for treatment decisions was safe and did not result in significant over- or undertreatment. Use of SG for treatment decisions under supervised inpatient conditions is a suitable alternative to repeated fingerstick glucose monitoring. Outpatient studies using SG in real-time are needed.

The Clinical Benefits and Accuracy of Continuous Glucose Monitoring Systems in Critically Ill Patients-A Systematic Scoping Review

Continuous Glucose Monitoring (CGM) systems could improve glycemic control in critically ill patients. We aimed to identify the evidence on the clinical benefits and accuracy of CGM systems in these patients. For this, we performed a systematic search in Ovid MEDLINE, from inception to 26 July 2016. Outcomes were efficacy, accuracy, safety, workload and costs. Our search retrieved 356 articles, of which 37 were included. Randomized controlled trials on efficacy were scarce (n = 5) and show methodological limitations. CGM with automated insulin infusion improved time in target and mean glucose in one trial and two trials showed a decrease in hypoglycemic episodes and time in hypoglycemia. Thirty-two articles assessed accuracy, which was overall moderate to good, the latter mainly with intravascular devices. Accuracy in critically ill children seemed lower than in adults. Adverse events were rare. One study investigated the effect on workload and cost, and showed a significant reduction in both. In conclusion, studies on the efficacy and accuracy were heterogeneous and difficult to compare. There was no consistent clinical benefit in the small number of studies available. Overall accuracy was moderate to good with some intravascular devices. CGM systems seemed however safe, and might positively affect workload and costs.

Accuracy of 2 Different Continuous Glucose Monitoring Systems in Patients Undergoing Cardiac Surgery

BACKGROUND

Continuous glucose monitoring (CGM) is today provided by various techniques. This study aims to compare two different CGM-systems: the FreeStyle Libre subcutaneous continuous glucose monitoring system (SC-CGM) and the Eirus intravascular microdialysis continuous glucose monitoring system (MD-CGM) in patients undergoing cardiac surgery.

METHODS

A total of 26 patients were equipped with both the SC-CGM and the MD-CGM systems. The SC-CGM system was placed subcutaneously in the left upper-arm and the MD-CGM system was placed in the superior vena cava. Reference blood glucose values were obtained by analyzing arterial blood in a blood gas analyzer. Reference glucose values were then paired with glucose values from both CGM-systems and analyzed for accuracy.

RESULTS

In all, 514 paired MD-CGM/arterial blood gas glucose values and 578 paired SC-CGM/arterial blood gas glucose values were obtained. Mean difference (SD) for the MD-CGM system was 0.9 (15.1) mg/dl and for the SC-CGM system -43.4 (20) mg/dl. ISO criteria (ISO15197:2013) were not met by either CGM system. In the Clarke error grid, all paired samples were within the zones AB for the MD-CGM system, and 94% in zone A. For the SC-CGM system, 99.1% of the paired samples were within zones AB, and 18.9% in zone A. Both the MD-CGM and the SC-CGM systems were reliable and used without complications.

CONCLUSIONS

These results indicate that the Eirus intravascular microdialysis system monitors glucose continuously with superior accuracy compared to the FreeStyle Libre subcutaneous glucose monitoring system, which repeatedly measured a glucose value that was lower than the reference method.

Accuracy, reliability, feasibility and nurse acceptance of a subcutaneous continuous glucose management system in critically ill patients: a prospective clinical trial

BACKGROUND

Continuous glucose monitoring (CGM) has not yet been implemented in the intensive care unit (ICU) setting. The purpose of this study was to evaluate reliability, feasibility, nurse acceptance and accuracy of the Medtronic Sentrino(®) CGM system in critically ill patients.

METHODS

Sensors were inserted into the subcutaneous tissue of the patient's thigh, quantifying interstitial glucose concentration for up to 72 h per sensor. Reliability and feasibility analysis included frequency of data display, data gaps and reasons for sensor removal. We surveyed nurse acceptance in a questionnaire. For the accuracy analysis, we compared sensor values to glucose values obtained via blood gas analysis. Potential benefits of CGM were investigated in intra-individual analyses of factors, such as glycemic variability or time in target range achieved with CGM compared to that achieved with intermittent glucose monitoring.

RESULTS

The device generated 68,655 real-time values from 31 sensors in 20 critically ill patients. 532 comparative blood glucose values were collected. Data were displayed during 32.5 h [16.0/62.4] per sensor, which is 45.1 % of the expected time of 72 h and 84.8 % of 37.9 h actual monitoring time. 21 out of 31 sensors were removed prematurely. 79.1 % of the nursing staff rated the device as not beneficial; the response rate was one-third. Mean absolute relative difference was 15.3 % (CI 13.5-17.0 %). Clarke error grid: 76.9 % zone A, 21.6 % zone B, 0.2 % zone C, 0.9 % zone D, 0.4 % zone E. Bland-Altman plot: mean bias +0.53 mg/dl, limits of agreement +64.6 and -63.5 mg/dl. Accuracy deteriorated during elevated glycemic variability and in the hyperglycemic range. There was no reduction in dysglycemic events during CGM compared to 72 h before and after CGM. If CGM was measuring accurately, it identified more hyperglycemic events when compared to intermittent measurements. This study was not designed to evaluate potential benefits of CGM on glucose control.

CONCLUSIONS

The subcutaneous CGM system did not perform with satisfactory accuracy, feasibility, or nursing acceptance when evaluated in 20 medical-surgical ICU patients. Low point accuracy and prolonged data gaps significantly limited the potential clinical usefulness of the CGM trend data. Accurate continuous data display, with a MARD < 14 %, showed potential benefits in a subgroup of our patients. Trial registration NCT02296372; Ethic vote Charité EA2/095/14.

Accuracy of Continuous Glucose Monitoring in Patients After Total Pancreatectomy with Islet Autotransplantation

BACKGROUND

Among postsurgical and critically ill patients, malglycemia is associated with increased complications. Continuous glucose monitoring (CGM) in the inpatient population may enhance glycemic control. CGM reliability may be compromised by postsurgical complications such as edema or vascular changes. We utilized Clarke Error Grid (CEG) and Surveillance Error Grid (SEG) analysis to evaluate CGM performance after total pancreatectomy with islet autotransplantation.

MATERIALS AND METHODS

This subanalysis evaluated Medtronic Enlite 2 CGM values against YSI serum glucose in seven post-transplant patients (86% female; 38.6 ± 9.4 years) on artificial pancreas for 72 h at transition from intravenous to subcutaneous insulin. Sensor recalibration occurred for absolute relative difference (ARD) ≥20% x2, ≥30% x1, or by investigator discretion based on trend.

RESULTS

Sensor analysis showed mean absolute relative difference (MARD) of 11.0% ± 11.5%. The sensors were recalibrated 8.3 times/day; active sensor was switched 1.4 times/day. Calibration factor was 7.692 ± 3.786 mg/nA·dL (target = 1.5-20 mg/nA·dL). CEG analysis showed 86.1% of pairs in Zone A (clinically accurate zone) and 99.4% of pairs in Zones A + B (low risk of error). SEG analysis of hypoglycemia/hyperglycemia risk showed 92.22% of pairs in the "no risk" zone, 5.96% of pairs in the "slight lower" risk zone, 1.01% of pairs in the "slight higher" risk zone, and only 0.81% of pairs in the "moderate lower" risk zone.

CONCLUSIONS

Overall performance of the Medtronic Enlite 2 CGM in the post-transplant population was reasonably good with "no risk" or "slight lower" risk by SEG analysis and high CGM-YSI agreement by CEG analysis; however, frequent recalibrations were required in this intensive care population.

Randomized Evaluation of Glycemic Control in the Medical Intensive Care Unit Using Real-Time Continuous Glucose Monitoring (REGIMEN Trial)

BACKGROUND AND OBJECTIVE

Hyperglycemia occurs commonly in patients admitted to medical intensive care units (MICUs). Whether real-time (RT) continuous glucose monitoring (CGM) improves glycemic control and variability and reduces hypoglycemia in severely ill MICU patients with an Acute Physiology and Chronic Health Evaluation II (APACHE-II) score of ≥20 has not been studied.

SUBJECTS AND METHODS

Thirty-five patients (66 ± 10 years of age; APACHE-II score, 28 ± 6) were randomly assigned to RT-CGM (n = 16) using the GlucoDay(®)S (A. Menarini Diagnostics, Florence, Italy) device or to blinded CGM. Insulin was infused using a modified Yale protocol targeting a blood glucose level between 80 and 120 mg/dL. Outcome measures were percentage of time in normoglycemia (80-110 mg/dL) and in hypoglycemia (<60 mg/dL), glycemic variability (SD, coefficient of variation, mean amplitude of glucose excursions, and mean of daily differences), and CGM accuracy (error grid analyses, Bland-Altman bias plot, and mean absolute relative deviation).

RESULTS

During 96 h of monitoring, glycemia reached target (80-110 mg/dL) in 37 ± 15%, was between 70 and 180 mg/dL in 91 ± 10%, and <60 mg/dL in 2 ± 2% of the time. In the RT-CGM group glycemia averaged 119 ± 17 mg/dL versus 122 ± 11 mg/dL in the control group. Parameters of glucose variability and percentages of time at target glycemia and in hypoglycemia were similar between groups. GlucoDayS values and arterial glycemia correlated well, with 98.6% of data falling in Zones A and B of the error grid analysis. Mean absolute relative devation was 11.2%.

CONCLUSIONS

RT-CGM did not ameliorate glucose control or variability; neither did it reduce the number of hypoglycemic events, but our insulin infusion protocol led to overall good glucose control without a significant hypoglycemia risk, making further improvement difficult.

Accuracy of Intra-arterial and Subcutaneous Continuous Glucose Monitoring in Postoperative Cardiac Surgery Patients in the ICU

BACKGROUND

The GluCath® intra-arterial continuous glucose monitoring (IA-CGM) system uses a novel quenched chemical fluorescence sensing mechanism to optically measure blood glucose when deployed in the radial artery. The aim of this study was to compare the accuracy of the IA-CGM and the FreeStyle Navigator® subcutaneous continuous glucose monitoring (SC-CGM) system with standard care.

METHODS

After admission to the intensive care unit (ICU), the IA-CGM was inserted via a 20 gauge radial arterial study catheter and the SC-CGM was placed at the abdominal wall of postoperative cardiac surgery patients with an expected ICU length of stay > 24 hours. Each device was calibrated according to manufacturer instructions. Glucose values of both CGM systems were blinded for the clinical staff. Reference blood glucose samples were collected from the study catheter every 1-2 hours for at least 24 hours and analyzed on a Radiometer ABL blood gas analyzer.

RESULTS

The IA-CGM and SC-CGM sensors were successfully inserted in 8 subjects. Accuracy assessment was performed with 183 paired points: 85.8% of the IA-CGM measurements and 84.2% of the SC-CGM measurements met ISO 15197:2003 glucometer criteria (within 20%) across a 79-248 mg/dl (4.4-13.8 mmol/L) glucose range. Overall ± SD mean absolute relative difference was 12.3 ± 11.3% for IA-CGM and 11.1 ± 8.3% for SC-CGM (difference -1.2%, 95% CI -3.3 to 0.8; P = .24).

CONCLUSIONS

The IA-CGM system directly measured arterial blood glucose and did not interfere with clinical care. However, accuracy was similar to that of the less invasive SC-CGM device.

Point accuracy and reliability of an interstitial continuous glucose-monitoring device in critically ill patients: a prospective study

Introduction

There is a need for continuous glucose monitoring in critically ill patients. The objective of this trial was to determine the point accuracy and reliability of a device designed for continuous monitoring of interstitial glucose levels in intensive care unit patients.

Methods

We evaluated point accuracy by comparing device readings with glucose measurements in arterial blood by using blood gas analyzers. Analytical and clinical accuracy was expressed in Bland-Altman plots, glucose prediction errors, and Clarke error grids. We used a linear mixed model to determine which factors affect the point accuracy. In addition, we determined the reliability, including duration of device start-up and calibration, skips in data acquisition, and premature disconnections of sensors.

Results

We included 50 patients in whom we used 105 sensors. Five patients from whom we could not collect the predefined minimum number of four consecutive comparative blood draws were excluded from the point accuracy analysis. Therefore, we had 929 comparative samples from 100 sensors in 45 patients (11 (7 to 28) samples per patient) during 4,639 hours (46 (27 to 134) hours per patient and 46 (21 to 69) hours per sensor) for the accuracy analysis. Point accuracy did not meet the International Organization for Standardization (ISO) 14971 standard for insulin dosing accuracy but did improve with increasing numbers of calibrations and was better in patients who did not have a history of diabetes. Out of 105 sensors, 60 were removed prematurely for a variety of reasons. The device start-up time was 49 (43 to 58) minutes. The number of skips in data acquisition was low, resulting in availability of real-time data during 95% (89% to 98%) of the connection time per sensor.

Conclusions

The point accuracy of a device designed for continuous real-time monitoring of interstitial glucose levels was relatively low in critically ill patients. The device had few downtimes, but one third of the sensors were removed prematurely because of unresolved sensor- or device-related problems.

Trial registration

Netherlands Trial Registry number: NTR3827. Registered 30 January 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0757-4) contains supplementary material, which is available to authorized users.

Glucose control in the ICU: is there a time for more ambitious targets again?

During the last 2 decades, the treatment of hyperglycemia in critically ill patients has become one of the most discussed topics in the intensive medicine field. The initial data suggesting significant benefit of normalization of blood glucose levels in critically ill patients using intensive intravenous insulin therapy have been challenged or even neglected by some later studies. At the moment, the need for glucose control in critically ill patients is generally accepted yet the target glucose values are still the subject of ongoing debates. In this review, we summarize the current data on the benefits and risks of tight glucose control in critically ill patients focusing on the novel technological approaches including continuous glucose monitoring and its combination with computer-based algorithms that might help to overcome some of the hurdles of tight glucose control. Since increased risk of hypoglycemia appears to be the major obstacle of tight glucose control, we try to put forward novel approaches that may help to achieve optimal glucose control with low risk of hypoglycemia. If such approaches can be implemented in real-world practice the entire concept of tight glucose control may need to be revisited.

Performance of the Medtronic Sentrino continuous glucose management (CGM) system in the cardiac intensive care unit

BACKGROUND

Maintaining glucose in the target range, while avoiding hypoglycemia, is challenging in critically ill patients. We investigated the performance and safety of Medtronic Sentrino, a newly developed continuous glucose management (CGM) system for critically ill adults.

METHODS

This was a prospective, single-center, single-arm, open-label study in adult patients with cardiac ICU admission. Sentrino subcutaneous glucose sensors were inserted into patients' thigh with planned study participation of 72 h. Sensor glucose results were displayed, and the system's alerts and alarms fully enabled. Reference blood glucose was collected from central venous catheter and analyzed with a blood gas analyzer. Treatment decisions were made independently of sensor glucose values, according to the existing standard of care.

RESULTS

A total of 21 patients were enrolled; all successfully completed the study. Sensor glucose values were displayed 96% of the time, and 870 paired blood glucose-sensor glucose points were analyzed. Overall mean absolute relative difference (MARD) was 12.8% (95% CI 11.9% to 13.6%). No clinically significant differences in accuracy were seen within subgroups of hemodynamic status (MARD 12.3% and 13.1% for compromised vs stable hemodynamics). Consensus grid analysis showed >99% of sensor glucose values within A/B zones. No device or study-related adverse events were reported. 100% of clinicians found Sentrino easy to use after two patients.

CONCLUSIONS

In our single-center experience, Sentrino CGM system demonstrated good accuracy and reliability, with no device-related adverse events in critically ill cardiac patients, and was easy to use and integrate in the cardiac ICU.

TRIAL REGISTRATION NUMBER

NCT01763567.