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Abstract

Introduction: Stress hyperglycemia is a common result of critical illness, severe trauma, or major surgery, and is often directly correlated with increased morbidity and mortality. Control of blood glucose (BG) levels during critical illness results in improved outcomes but intermittent measurement of blood glucose (BG) may miss episodes of hyper- and hypoglycemia that a continuous monitor can quickly identify to facilitate improved glycemic control. The Symphony® Transdermal Continuous Glucose Monitor (tCGM) is a non-invasive system designed to address this need, using the Prelude® SkinPrep System to prepare the skin, providing interstitial fluid (ISF) access at the measurement site. Hypothesis: The Symphony tCGM system is able to continuously monitor glucose non-invasively on sites prepared with Prelude SkinPrep in the surgical intensive care unit. Methods: Fifteen adult patients undergoing cardiac surgery were evaluated. Prelude was used to prepare the skin and a tCGM sensor was applied to each of two test sites. Frequent venous reference blood samples were taken from IV lines at 30-60 minute intervals. The reference BG values were measured with a YSI 2300 Stat+ glucose analyzer. At the conclusion of the study, the skin at the test sites was inspected for redness or any other effects. Accuracy of the tCGM data relative to the reference BG values was determined using Continuous Glucose Error Grid Analysis (CG-EGA) and mean absolute relative difference (MARD). Results: Using over 600 Symphony tCGM glucose readings paired with reference BG measurements, CG-EGA showed that 99.6% of the readings were clinically accurate. The MARD was 12.3%. Values for BG measurements ranged from 73 to 251 mg/dL. No unanticipated adverse device effects were reported for the Prelude skin permeation or the Symphony tCGM. Conclusions: The Symphony tCGM system is able to continuously monitor glucose in cardiac surgery intensive care patients by transdermally measuring glucose in ISF. This non-invasive approach represents a simple, convenient, needle-free solution for continuous glucose monitoring in critically ill patients.