Hydrogen gas therapy improves survival rate and neurological deficits in subarachnoid hemorrhage rats: a pilot study
Camara R, Matei N, Camara J, Enkhjargal B, Tang J, Zhang JH. · Medical Gas Research. 2019;9(2):74–79.
Study at a glance
Preclinical
35 adult male Sprague-Dawley rats randomized to sham, subarachnoid hemorrhage plus room air or subarachnoid hemorrhage plus H₂/O₂.
Two-hour chamber inhalation beginning 0.5 hours after hemorrhage and repeated at 8 and 18 hours. · The article reports 66% H₂ at a total flow of 3 L/min and explains an intended stoichiometric H₂:O₂ ratio of 2:1.
Three two-hour sessions within the first 20 hours after hemorrhage; outcomes at 24 and 72 hours.
Left-forelimb placement improved at 24 hours and 72-hour survival was 8/8 with H₂/O₂ versus 4/6 with air. Hemorrhage grade did not differ between treated and air groups, and neurological function did not differ significantly at 72 hours.
Pilot-sized groups, only male rats, short 72-hour follow-up, early deaths can bias neurological scores among survivors, one simple behavioral test and no experimental mechanism testing. NIH funded the work; authors declared no conflict, while the commercial generator and manufacturer were identified.
What kind of evidence is this?
Preclinical
Randomized blinded pilot study in a rat endovascular-perforation subarachnoid-hemorrhage model
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
35 adult male Sprague-Dawley rats randomized to sham, subarachnoid hemorrhage plus room air or subarachnoid hemorrhage plus H₂/O₂.
35 rats overall. Outcome-specific groups at 24 hours were sham n=6, air n=5 and H₂/O₂ n=4; 72-hour survival compared air n=6 with H₂/O₂ n=8.
Three two-hour sessions within the first 20 hours after hemorrhage; outcomes at 24 and 72 hours.
Two-hour chamber inhalation beginning 0.5 hours after hemorrhage and repeated at 8 and 18 hours.
Brown's gas / oxyhydrogen generated by water electrolysis at approximately 66.6% H₂ and 33.3% O₂.
The article reports 66% H₂ at a total flow of 3 L/min and explains an intended stoichiometric H₂:O₂ ratio of 2:1.
Approximately 2,000 mL/min, calculated directly from the reported 2:1 mixture at 3 L/min.
Approximately 1,000 mL/min, calculated directly from the reported 2:1 mixture at 3 L/min.
The same chamber schedule with room air; sham animals underwent surgery without arterial perforation.
Outcomes and reported result
Subarachnoid-hemorrhage grade, blinded forelimb-placement testing and 72-hour survival.
Left-forelimb placement improved at 24 hours and 72-hour survival was 8/8 with H₂/O₂ versus 4/6 with air. Hemorrhage grade did not differ between treated and air groups, and neurological function did not differ significantly at 72 hours.
The complete free PMC article and figures were checked for randomization/blinding, exact gas composition and flow, outcome-specific samples, survival, short- and later neurological findings, limitations, funding and conflicts.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Pilot-sized groups, only male rats, short 72-hour follow-up, early deaths can bias neurological scores among survivors, one simple behavioral test and no experimental mechanism testing. NIH funded the work; authors declared no conflict, while the commercial generator and manufacturer were identified.
Experimental aneurysmal-hemorrhage model in rats; it does not establish survival or neurological benefit in people with subarachnoid hemorrhage.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 31249255 · DOI: 10.4103/2045-9912.260648
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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