Advances in the Diagnosis of Sepsis: Hydrogen Sulfide as a Prognostic Marker of Septic Shock Severity

Hydrogen sulfide (H(2)S) is a third known gasotransmitter. Most of the time it was knows as a poisonous gas. In last 30 years, we are seeing change in its perception. Scientists have discovered its major role in different organ systems. It is endogenously produced in various tissues and its production is influenced by many factors. In normal, physiological conditions only 20% of H(2)S is in its free form. The role of H(2)S is very wide. It acts as a signaling molecule, has influence on vascular tone, inflammatory response, scavenges reactive oxygen species, can be cytoprotective and can even reduce the extent of myocardial ischemia. Different studies have shown H(2)S has considerable influence in pathology of sepsis and its outcome. High free plasma levels of H(2)S are predictor of unfavorable outcome. Findings show that moderate free plasma levels of H(2)S have protective effect. Paradoxical very low free plasma levels of H(2)S, seen in patients with chronic heart failure, are also predictor of severity of disease and poor outcome. We presume that relationship between morbidity/mortality and concentration of H(2)S has a wide U-shape curve dependence. New researches with discovery of H(2)S agonists and antagonists could open new ways in understanding different pathologies and ability to treat them. Recent advances in the identification of H(2)S agonists and antagonists may help in forwarding our understanding of pathomechanisms and hence their treatment.