Six Hours of Hydrogen Gas Inhalation Has a Neuroprotective Effect Even in Piglets with Delayed Functional Recovery

Combined therapeutic hypothermia (TH) and 24-h hydrogen (H₂) gas inhalation reduces seizure burden in piglets in the latent phase of hypoxic-ischemic (HI) injury versus TH alone. Nevertheless, the effects of H₂ gas in the earliest phase following resuscitation were unclear.

After HI insult, 17 piglets ≤24 h old were divided into a HI insult group (HI, n = 8) and a HI and H₂ gas group (HI-H₂, 2.1%-2.7% H₂ gas, 6 h, n = 9). Time to recovery to a normal amplitude-integrated electroencephalogram background (RT-aEEG) was examined for 6 h after HI insult and undamaged neurons were counted.

The duration of low-amplitude (<5 μV) EEG after insult was not different between the two groups. Undamaged neuron numbers were significantly higher in the HI-H₂ group than in the HI group (p < 0.01), although RT-aEEG was not different.

Six hours of H₂ gas inhalation initiated from resuscitation significantly increased the number of undamaged neurons compared to the untreated group, although there was no difference in RT-aEEG. Six hours of hydrogen gas inhalation exerts a neuroprotective effect even in piglets with delayed functional recovery.