Nitric Oxide and its Metabolites in the Critical Phase of Illness: Rapid Biomarkers in the Making

The potential of nitric oxide (NO) as a rapid assay biomarker, one that could provide a quantum leap in acute care, remains largely untapped. NO plays a crucial role as bronchodilator, vasodilator and inflammatory mediator. The main objective of this review is to demonstrate how NO is a molecule of heavy interest in various acute disease states along the emergency department and critical care spectrum: respiratory infections, central nervous system infections, asthma, acute kidney injury, sepsis, septic shock, and myocardial ischemia, to name just a few. We discuss how NO and its oxidative metabolites, nitrite and nitrate, are readily detectable in several body compartments and fluids, and as such they are associated with many of the pathophysiological processes mentioned above. With methods such as high performance liquid chromatography and chemiluminescence these entities are relatively easy and inexpensive to analyze. Emphasis is placed on diagnostic rapidity, as this relates directly to quality of care in acute care situations. Further, a rationale is provided for more bench, translational and clinical research in the field of NO biomarkers for such settings. Developing standard protocols for the aforementioned disease states, centered on concentrations of NO and its metabolites, can prove to revolutionize diagnostics and prognostication along a spectrum of clinical care. We present a strong case for developing these biomarkers more as point-of-care assays with potential of color gradient test strips for rapid screening of disease entities in acute care and beyond. This will be relevant to global health.