The Neurochemical Signature of Cardiac Arrest: A Multianalyte Online Microdialysis Study

This work describes the use of high resolution online microdialysis coupled with a wireless microfluidic electrochemical sensing platform for continuous monitoring of the effect of cardiac arrest and resuscitation methods on brain glucose and other key neurochemicals in a porcine model. The integrated portable device incorporates low-volume three-dimensional (3D) printed microfluidic flow cells containing enzyme-based biosensors for glucose, lactate and glutamate measurement and a complementary metal-oxide semiconductor (CMOS)-based ion-sensitive field effect transistor (ISFET) for potassium measurement. Both analysis systems incorporate wireless electronics forming a complete compact system that is ideal for use in a crowded clinical environment. Using this integrated system we were able to build a signature of the neurochemical impact of cardiac arrest and resuscitation. Our results demonstrate the almost complete depletion of brain glucose following cardiac arrest and the subsequent increase in lactate, highlighting the vulnerability of the brain while the blood flow is compromised. Following a return of spontaneous circulation, glucose levels increased again and remained higher than baseline levels. These trends were correlated with simultaneous blood measurements to provide further explanation of the metabolic changes occurring in the brain. In addition, the onset of cardiac arrest corresponded to a transient increase in potassium. In most cases glutamate levels remained unchanged after cardiac arrest, while in some cases a transient increase was detected. We were also able to validate the trends seen using online microdialysis with traditional discontinuous methods; the two methods showed good agreement although online microdialysis was able to capture dynamic changes that were not seen in the discontinuous data.