Development of smart sensors for continuous monitoring of blood gases and key laboratory parameters for extracorporeal membrane oxygenation (ECMO)

Critical ill patients often experience rapid changes in their clinical conditions, which require frequent blood tests. While cardiovascular and respiratory data are commonly available at the bedside using standard monitoring systems for hemodynamics and mechanical ventilation, laboratory parameters are often delayed by some hours. In contrast, the continuous measurement of some parameters at the bedside (e.g. glucose and lactate levels) would allow direct monitoring and therapeutic response in critical and dynamic situations. Glucose plays a central role when monitoring liver function in patients with multi-organ failure or acute diabetic states e.g. after total pancreatectomy. Lactate is one of the best established markers representing adequate tissue (micro-) perfusion, frequently used in different states of shock, especially for guiding fluid resuscitation and differentiated catecholaminergic support. Frequent blood gas analysis are crucial for adjustment of mechanical ventilation or extracorporeal membrane oxygenation (ECMO) systems as well as interpreting respiratory or metabolic causes of acid-base disturbances. Although point-of-care devices are available at the bedside for certain parameters, e.g., blood gases and some coagulation tests, certain variables could significantly improve patient care and safety when measured continuously and in real-time at the bedside. Furthermore, a considerable amount of blood is used when laboratory or conventional point of care tests are applied frequently, where the amount of blood used for testing can be up to 40 milliliters in 24h. Given an average ICU length of stay of 10 days this results in approximately 400 ml blood loss only for laboratory analysis which is equivalent to 1 unit packed red blood cells. Notably, transfusion of blood products is associated with worse outcome in critical ill patients. Current available ECMO-devices are able to measure blood flow and pressures in the ECMO circuit, as well as oxygen saturation and hemoglobin/ hematocrit concentration in real-time by means of pressure, flow and optical sensors. However, none of those sensors is able to perform blood-based tests such as blood gas analysis or lactate levels. These measurements may improve ECMO therapy and allows earlier identification of oxygenator circuit failure. One of the main goals of differentiated lung support concepts is to find the optimal balance between the invasiveness of mechanical ventilation and ECMO settings. Therefore, online measurements of key laboratory values such as blood gases would certainly improve quality of care towards more individualized care.