Accuracy and stability of an arterial sensor for glucose monitoring in a porcine model using glucose clamp technique

Abstract

Intravascular glucose sensors have the potential to improve and facilitate glycemic control in critically ill patients and might overcome measurement delay and accuracy issues. This study investigated the accuracy and stability of a biosensor for arterial glucose monitoring tested in a hypo- and hyperglycemic clamp experiment in pigs. 12 sensors were tested over 5 consecutive days in 6 different pigs. Samples of sensor and reference measurement pairs were obtained every 15 minutes. 1337 pairs of glucose values (range 37-458 mg/dl) were available for analysis. The systems met ISO 15197:2013 criteria in 99.2% in total, 100% for glucose <100 mg/dl (n = 414) and 98.8% for glucose ≥100 mg/dl (n = 923). The mean absolute relative difference (MARD) during the entire glycemic range of all sensors was 4.3%. The MARDs within the hypoglycemic (<70 mg/dl), euglycemic (≥70-180 mg/dl) and hyperglycemic glucose ranges (≥180 mg/dl) were 6.1%, 3.6% and 4.7%, respectively. Sensors indicated comparable performance on all days investigated (day 1, 3 and 5). None of the systems showed premature failures. In a porcine model, the performance of the biosensor revealed a promising performance. The transfer of these results into a human setting is the logical next step.

Figure 1

B. Braun SGC^PLUS blood glucose measurement system. The left picture indicates the reusable part of the sensor as attached to the patient arm (symbolic picture), responsible for optical activation and read-out of the sensor chemistry, and the disposable part (black/green) hosting the sensor chemistry and being connected to the arterial line. The right column of pictures indicates the principle functionality of the optical measurement technology as described in more detail in the document.

Figure 2

A Glucose clamp scheme for each study day. The Bins are illustrating different glucose areas B Percentual distribution of samples according to ISO 15197:2013.

Figure 3

1337 sensor-reference pairs displayed in the adjusted Bland-Altman plot including indication of fulfilment of ISO 15197:2013 criteria (15 mg/dl for glucose values <100 mg/dl and 15% for glucose values ≥100 mg/dl, bold black line). On the x-axis the reference glucose values are indicated. On the y-axis the deviation in mg/dl from sensor of 1337 sensor-reference pairs.

Figure 4

Parkes Error Grid for 1337 sensor-reference value pairs: On the y-axis sensor glucose is displayed, on the x-axis reference glucose is indicated. The grid is divided into zones displaying the degree of potential risk caused by erroneous measurements: values in zone A do not alter clinical action; zone B indicates altered clinical action with small or no significant effect on clinical outcome; zone C shows altered clinical action with probable effect on clinical outcome; zone D results in altered clinical action which could be associated with significant medical risk; and zone E causes altered clinical action which could have dangerous consequences.