Initial experience with continuous intra-arterial fluorescent glucose monitoring in patients in the ICU following cardiac surgery

Abstract

Introduction Continuous glucose monitoring (CGM) in ICUs has the potential to improve patient safety and outcomes. The GluCath Intravascular CGM System uses a novel quenched chemical fluorescence sensing mechanism to measure glucose concentration (BG) in venous or arterial blood. This is the first report of its use in cardiac surgery patients. Methods This ongoing clinical study is evaluating the system deployed via a standard 20G radial artery catheter inserted for routine care in 20 patients undergoing cardiac surgery. Data are presented from five run-in patients. Outcome measures are qualitative (ease-of-use, workflow fit) and quantitative (accuracy vs. reference analyzer). Sensors were inserted shortly after ICU admission with placement confirmed by ultrasound and in vivo calibration 30 minutes later. Clinical staff managed blood glucose according to usual protocols. Glucose values were recorded each minute for 24 hours; hourly reference samples from the same arterial catheter were analyzed on a Radiometer ABL Blood Gas Analyzer. Results The sensor was successfully deployed in all five patients and did not interfere with clinical care, blood pressure monitoring or sampling. One patient suffered a cardiopulmonary arrest; the sensor functioned successfully during resuscitation and urgent return to the operating room. One hundred and twenty reference samples ranging from 5.9 to 13.4 mmol/l were collected; 107/120 (89.2%) of GluCath measurements met ISO 15197 criteria (within +/-20% of reference when BG >4.2 mmol/l; Figure 1). In Subject 1 the sensor was inadvertently retracted into the arterial catheter during the study, leading to measurement error from arterial flush solution contamination. In a sensitivity analysis excluding this patient, 89/95 (93.7%) of measurements met ISO 15197 with a mean absolute relative difference of 9.4%. Conclusion The GluCath System measured glucose concentration continuously in a cardiac surgery ICU without compromising arterial line function or patient care. In all patients the sensor operated without interruption for 24 hours following a single in vivo calibration. (Figure presented).