Application of Hydrogen in Hemodialysis: A Brief Review with Emphasis on the Quantification of Dissolved H2

Chronic kidney disease patients frequently manifest signs of oxidative and inflammatory stress associated with the lifesaving haemodialysis therapy itself. Lately, hydrogen has gained traction as an antioxidant with a deluge of reports bearing evidence of its potential in treating a plethora of medical conditions. Among the various animal models and clinical studies communicated, a novel hydrogen administration method revolving around H2-rich dialysate stands out. Over the past decade, hydrogen enriched haemodialysis (E-HD) has steadily been gaining ground thanks to its ameliorating effect on oxidative and inflammatory complications arising during haemodialysis. To complement this modality, a hydrogen water monitoring system (HWMS) has been developed by Pureron Japan Co., Ltd to assist in determining the levels of dissolved hydrogen in liquids. Preliminary investigations have validated the sensitivity and accuracy of the contactless hydrogen sensor and its applicability in various clinical settings. Nevertheless, a few setbacks such as the long response time, and range-specific accuracy prompted further examination and in-depth analysis of its capabilities. To achieve that, three such sensors have been integrated in an in vitro haemodialysis circuit to monitor H2 concentration at the dialyzer’s inlet–outlet. Moreover, experiments have been conducted using a regular dialyzer as well as a modified one with a purely diffusive coating, in order to discern the nature of hydrogen transfer through the capillary membrane and distinguish between ultrafiltration and diffusion.