Low-Flow Nasal Cannula Hydrogen Therapy

BACKGROUND: Molecular hydrogen (H(2)) is a biologically active gas that is widely used in the healthcare sector. In recent years, on-site H(2) gas generators, which produce high-purity H(2) by water electrolysis, have begun to be introduced in hospitals, clinics, beauty salons, and fitness clubs because of their ease of use. In general, these generators produce H(2) at a low-flow rate, so physicians are concerned that an effective blood concentration of H(2) may not be ensured when the gas is delivered through a nasal cannula. Therefore, this study aimed to evaluate blood concentrations of H(2) delivered from an H(2) gas generator via a nasal cannula. METHODS: We administered 100% H(2), produced by an H(2) gas generator, at a low-flow rate of 250 mL/min via a nasal cannula to three spontaneously breathing micro miniature pigs. An oxygen mask was placed over the nasal cannula to administer oxygen while minimizing H(2) leakage, and a catheter was inserted into the carotid artery to monitor the arterial blood H(2) concentration. RESULTS: During the first hour of H(2) inhalation, the mean (standard error (SE)) H(2) concentrations and saturations in the arterial blood of the three pigs were 1,560 (413) nL/mL and 8.85% (2.34%); 1,190 (102) nL/mL and 6.74% (0.58%); and 1,740 (181) nL/mL and 9.88% (1.03%), respectively. These values are comparable to the concentration one would expect if 100% of the H(2) released from the H(2) gas generator is taken up by the body. CONCLUSIONS: Inhalation of 100% H(2) produced by an H(2) gas generator, even at low-flow rates, can increase blood H(2) concentrations to levels that previous non-clinical and clinical studies demonstrated to be therapeutically effective. The combination of a nasal cannula and an oxygen mask is a convenient way to reduce H(2) leakage while maintaining oxygenation.