人工心肺下心臓手術における分子状水素吸入が酸化ストレスマーカーに与える影響
This prospective study examined the influence of inhaled molecular hydrogen on lipid peroxidation during cardiac valve surgery performed under cardiopulmonary bypass (CPB). Twenty patients were divided into a hydrogen inhalation group (n=11; 1.5–2.0% H2 delivered via ventilator circuit from intubation through surgery) and a control group (n=9; no H2). Blood samples were collected at four time points: after anesthesia induction, before CPB, after CPB termination, and 24 hours postoperatively. Lipid peroxidation was assessed via diene conjugates (DC), triene conjugates (TC), and Schiff bases (SB). In the hydrogen group, arterial TC and SB levels declined relative to baseline before CPB initiation and at 24 hours postoperatively, while venous DC elevation before CPB normalized by the post-CPB stage. The control group showed progressive increases in arterial SB and elevated venous TC and SB at 24 hours. The most pronounced reduction in oxidative stress markers in the hydrogen group occurred on postoperative day one, supporting the potential of intraoperative H2 inhalation as a safe antioxidant adjunct in cardiac surgery.
Inhaled molecular hydrogen is proposed to scavenge reactive oxygen species generated during cardiopulmonary bypass, thereby reducing lipid peroxidation end-products such as triene conjugates and Schiff bases in both arterial and venous blood.
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/34513069