Thermometric analysis of blood metabolites in ICU patients

Abstract

Real-time monitoring of patient’s blood metabolites, such as glucose and lactate, could potentially improve surgery and recovery outcomes for patients in surgical and intensive care units. Our enzyme thermometric biosensor which is based on flow injected calorimetric determination of immobilized enzyme reaction is capable of performing continuous, fast, and quantitative analysis of metabolites using whole blood. A key technical advantage the assay affords is the ability to use unpretreated whole blood. In this article, the enzyme thermometric biosensor was used, for the first time, to determine glucose and lactate concentrations in the blood of ICU patients. The linear detection range for glucose was 0.5–30 mM and 0.25–12 mM for lactate, using a 20 μL sample volume. A maximum sampling rate of 15 measurements per hour was achieved using venous blood samples, which corresponds to a 4-min measurement interval. In order to validate the accuracy of the results, a comparative analysis between the thermometric biosensor and the clinically applied instrument (LifeScan’s OneTouch®) which is based on disposable dry chemical reaction was performed using samples from 33 patients. The results showed a good correlation between the two methods for both glucose (r = 0.843, p < 0.0001) and lactate (r = 0.78, p = 0.0105). The ability to monitor metabolite levels and trends on a clinically relevant timescale of 5 min is critical for intensive monitoring of ICP and operative patients.