Inhalation of high-concentration hydrogen gas attenuates cognitive deficits in a rat model of asphyxia induced-cardiac arrest
Huang L, Applegate RL II, Applegate PM, Gong L, Ocak U, Boling W, Zhang JH. · Medical Gas Research. 2019;9(3):122–126.
Study at a glance
Preclinical
44 nine-month-old male Sprague-Dawley rats assigned to sham, cardiac arrest, post-arrest H₂/O₂ or pre- and post-arrest H₂/O₂ groups.
One hour before plus one hour after resuscitation, or two hours beginning one hour after resuscitation, in a treatment chamber. · The gas composition and generator model were reported, but total chamber flow was absent; component mL/min values therefore cannot be calculated.
One-hour pre- and post-treatment or two-hour post-treatment; cognitive and neuronal outcomes through day 18.
Both H₂/O₂ schedules improved selected water-maze measures and reduced CA1 neuronal degeneration at day 18. Day-7 T-maze differences versus untreated arrest were not significant, swimming speed did not differ, and treatment did not materially alter reported hemodynamic parameters.
Small male-rat groups, pre-treatment arm has limited clinical realism, no matched chamber-gas comparator described, follow-up only 18 days, multiple cognitive endpoints and mechanism not established. Authors reported no financial support and no conflicts; the commercial generator and manufacturer were identified.
What kind of evidence is this?
Preclinical
Four-group rat asphyxial-cardiac-arrest experiment comparing post-treatment with pre-plus-post treatment
Critical care and ischemia-reperfusion
Inhaled H₂
Information not yet classified
Some editorial classification fields are still pending. The source-reported outcomes and result are shown below; Hydrogenology does not infer a positive or negative signal from prose automatically.
Methods
44 nine-month-old male Sprague-Dawley rats assigned to sham, cardiac arrest, post-arrest H₂/O₂ or pre- and post-arrest H₂/O₂ groups.
44 rats: sham n=6, cardiac arrest n=13, post-treatment n=13 and pre-plus-post treatment n=12; cognitive/histology time-point analyses generally used n=6 per group.
One-hour pre- and post-treatment or two-hour post-treatment; cognitive and neuronal outcomes through day 18.
One hour before plus one hour after resuscitation, or two hours beginning one hour after resuscitation, in a treatment chamber.
Brown's gas / oxyhydrogen generated by water electrolysis at 67% H₂ and 33% O₂.
The gas composition and generator model were reported, but total chamber flow was absent; component mL/min values therefore cannot be calculated.
Not reported — total gas flow is absent.
33% O₂; mL/min flow not reported because total gas flow is absent.
Sham surgery and cardiac arrest without H₂/O₂ treatment; the article does not describe a matched chamber-gas exposure for untreated arrest animals.
Outcomes and reported result
Hemodynamics, day-7 T-maze, days 14–18 Morris water maze and hippocampal CA1 Fluoro-Jade neuronal degeneration.
Both H₂/O₂ schedules improved selected water-maze measures and reduced CA1 neuronal degeneration at day 18. Day-7 T-maze differences versus untreated arrest were not significant, swimming speed did not differ, and treatment did not materially alter reported hemodynamic parameters.
The complete free PMC article and figures were checked for group counts, schedule/composition, absent flow, positive and null cognitive/physiological findings, histology, limitations, support and conflicts.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Small male-rat groups, pre-treatment arm has limited clinical realism, no matched chamber-gas comparator described, follow-up only 18 days, multiple cognitive endpoints and mechanism not established. Authors reported no financial support and no conflicts; the commercial generator and manufacturer were identified.
Experimental asphyxial cardiac arrest in older rats; it does not establish cognitive benefit after human cardiac arrest.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 31552874 · DOI: 10.4103/2045-9912.266986
Free full article in PubMed Central.
Complete PMC article and PubMed metadata; full-text extraction checked 9 August 2026.
10 August 2026
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