Testing of a novel automated point-of-care analyzer for blood ammonium monitoring in a clinical setting.

Abstract

Certain diseases are marked by elevated ammonium levels in the blood, a condition known as hyperammonemia. Prompt detection and medical intervention are crucial to prevent potentially fatal outcomes. Therefore, ammonium levels should be monitored regularly, typically in referral hospitals where specialized and costly equipment is available. Although compact commercial devices are available for this purpose, none of them meet all the technical and analytical requirements needed for direct blood analysis, and current reported strategies have not been validated with enough samples to confirm results reliably. We present a robust and reliable automated point-of-care (POC) analyzer for the potentiometric determination of ammonium in blood. Comprising three computer-controlled modules-fluid management, detection, and data acquisition and transmission-this system combines portability, ease of use, and affordability. It can directly measure untreated blood samples, significantly reducing analysis time. Fully automated, it operates unsupervised with minimal lab personnel intervention. Analytical quality parameters include 5% RSD repeatability (n = 8), a limit of detection of 24 μM, a working range of 30-1000 µM and a sample volume of 215 µL. Successfully implemented in a hospital for 2 months, it analyzed 238 blood samples in parallel with the hospital's reference method showing comparable results (paired t-test, Passing-Bablok regression and Bland-Altman Plot) and randomly distributed errors, with a 4% accuracy calculated as mean error. Results indicate the POC analyzer effectiveness and reliability in a clinical setting compared to currently reported or commercially available equipment, being suitable for bedside monitoring of conditions associated with hyperammonemia in healthcare centers, including emergency rooms and clinics in developing countries.