低流量鼻カニューレを用いた水素ガス吸入における動脈血中水素濃度の検討
This animal study examined whether low-flow delivery of 100% hydrogen gas via nasal cannula could achieve meaningful arterial blood concentrations. Three spontaneously breathing micro miniature pigs received hydrogen at 250 mL/min through a nasal cannula, with an overlying oxygen mask to limit gas leakage while preserving oxygenation. Arterial hydrogen concentrations measured via carotid catheter during the first hour averaged 1,560, 1,190, and 1,740 nL/mL, corresponding to saturations of approximately 8.85%, 6.74%, and 9.88%, respectively. These concentrations were consistent with near-complete uptake of the hydrogen released by the generator. The findings indicate that even at low flow rates, electrolysis-based hydrogen generators can raise blood hydrogen to levels reported as biologically active in prior non-clinical and clinical investigations. The nasal cannula plus oxygen mask combination was identified as a practical approach for clinical settings.
Hydrogen gas produced by water electrolysis is inhaled via nasal cannula, absorbed across the pulmonary epithelium, and dissolved into arterial blood, achieving saturation levels comparable to full uptake of the delivered gas volume even at low flow rates.
For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.
See also:
https://h2-papers.org/en/papers/33029275