Real-Time Monitoring of Blood Parameters in the Intensive Care Unit: State-of-the-Art and Perspectives

Abstract

The number of patients in intensive care units has increased over the past years. Critically ill patients are treated with a real time support of the instruments that offer monitoring of relevant blood parameters. These parameters include blood gases, lactate, and glucose, as well as pH and temperature. Considering the COVID-19 pandemic, continuous management of dynamic deteriorating parameters in patients is more relevant than ever before. This narrative review aims to summarize the currently available literature regarding real-time monitoring of blood parameters in intensive care. Both, invasive and non-invasive methods are described in detail and discussed in terms of general advantages and disadvantages particularly in context of their use in different medical fields but especially in critical care. The objective is to explicate both, well-known and frequently used as well as relatively unknown devices. Furtehrmore, potential future direction in research and development of realtime sensor systems are discussed. Therefore, the discussion section provides a brief description of current developments in biosensing with special emphasis on their technical implementation. In connection with these developments, the authors focus on different electrochemical approaches to invasive and non-invasive measurements in vivo.

Keywords: blood parameters; critical care; electrochemistry; intensive care; monitoring.

Figure 1

Literature search method used in this review article.

Figure 2

Implantable devices for blood-glucose monitoring. (a) Hydrogel-modified fibre with fluorescence responsivity operating in the ears of mice and responding to blood-glucose levels. Adapted with permission from Yun Jung Heo et al. [73], (b) Subcutaneous device with boronic acid-based glucose responsive fluorescent dye protected within a hydrogel doped by antioxidant enzymes. Adapted with permission from Sawayama et al. [74].

Figure 3

Electrochemical blood parameter measurement techniques. (a) Cocaine detection using aptamer-based electrochemical sensor with a reference redox-reporter for signal drift correction. Adapted with permission from Li et al. [83], (b) In vivo kanamycin measurement with aptamer-based electrochemical sensor protected with agarose hydrogel. Adapted with permission from Li et al. [85], (c) Skin-like electrodes for the measurement of blood glucose by refiltration to the interstitial fluid. Adapted with permission from Chen et al. [88].