Front. Neurol.
Sec. Neurocritical and Neurohospitalist Care
doi: 10.3389/fneur.2022.996112

Influence of oxygen concentration on the neuroprotective effect of hydrogen inhalation in a rat model of cardiac arrest

Jianjie Wang1, Yiming Shen2, Jingru Li1, Bihua Chen1, Changlin Yin1 and  Yongqin Li1*
  • 1Army Medical University, China
  • 2Chongqing Emergency Medical Center, China
Provisionally accepted:
The final, formatted version of the article will be published soon.

Background: Post-cardiac arrest brain injury is the main cause of death in patients resuscitated from cardiac arrest. Previous studies demonstrated that hydrogen inhalation mitigate post-cardiac arrest brain injury. However, factors affecting the efficacy of hydrogen remain unknown. In the present study, we investigated the influence of oxygen concentration and targeted temperature on neuroprotective effect in a cardiac arrest rat model of ventricular fibrillation (VF).
Methods: Cardiopulmonary resuscitation (CPR) was initiated after 7 min of untreated VF in adult male Sprague-Dawley rats. Immediately following successful resuscitation, animals were randomized to be ventilated with 21% oxygen (21%O2), 2% hydrogen and 21% oxygen (2%H2+21%O2), 2% hydrogen and 50% oxygen (2%H2+50%O2), or 2% hydrogen and 98% oxygen (2%H2+98%O2) for 3 h. For each group, the target temperature was 37.5°C for half of the animals and was 35.0°C for the other half.
Results: No statistical differences in baseline measurements and CPR characteristics were observed among groups. For animals with normothermia, 2%H2+50%O2 (123[369] vs. 500[393], p=0.041) and 2%H2+98%O2 (73[66] vs. 500[393], p=0.002) groups had significantly lower neurological deficit scores (NDS) at 96-h and significantly higher survival (75.0% vs. 37.5%, p=0.033 and 81.3% vs. 37.5%, p=0.012) than 21%O2 group. For animals with hypothermia, no statistical difference in NDS among groups but 2%H2+98%O2 has significantly higher survival than 21%O2 group (93.8% vs. 56.3%, p=0.014).
Conclusions: In this cardiac arrest rat model, inhaling 2% hydrogen combined with high concentration of oxygen improved 96-h survival, either under normothermia or under hypothermia.

Keywords: Cardiac arrest and brain injuries, hydrogen inhalation, neurological outcome, Oxygen concentration, Targeted temperature management

Received: 17 Jul 2022; Accepted: 16 Aug 2022.

Copyright: © 2022 Wang, Shen, Li, Chen, Yin and Li. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Yongqin Li, Army Medical University, Chongqing, 400038, China