Continuous glucose and exhaled breath analysis in the Intensive Care Unit

This thesis covers several topics including studies on the accuracy of continuous glucose measurement (CGM) devices in the Intensive Care Unit (ICU). In addition, it is investigated whether an electronic nose (eNose) can be used to predict blood glucose levels in mechanically ventilated ICU patients. To investigate these topics, the thesis is divided into three parts. The first part contains studies on comparing and testing different CGM methods and devices. The second part contains studies on predicting blood glucose levels by analysis of exhaled breath in intubated and ventilated ICU patients. In the third and final part of this thesis, we focus on further development of exhaled breath analysis techniques and data analysis methods. The tested CGM devices in part I of this thesis had varying accuracy and low reliability due to problems with sensors and other disposables. Therefore, it cannot be recommended that any of the tested devices is used in clinical practice before these practical problems are overcome. In our systematic review in the second part of this thesis, we found that there is a possible association between volatile organic compounds in exhaled breath and blood glucose levels. Trying to get similar results in critically ill ICU patients using a continuous eNose however, was not successful. This means that currently, continuous exhaled breath analysis using an eNose cannot be used to accurately predict blood glucose levels in intubated, mechanically ventilated patients.