Hydrogen/oxygen mixed gas inhalation improves disease severity and dyspnea in patients with Coronavirus disease 2019 in a recent multicenter, open-label clinical trial
Guan WJ, Wei CH, Chen AL, Sun XC, Guo GY, Zou X, Shi JD, Lai PZ, Zheng ZG, Zhong NS. · Journal of Thoracic Disease. 2020;12(6):3448.
Study at a glance
Human
Hospitalized patients with COVID-19 and dyspnea at enrollment during the early 2020 outbreak in China.
H₂/O₂ inhalation by nasal cannula daily until discharge in addition to standard care. · Total flow was 6 L/min. Based on the intended 2:1 Brown's-gas ratio, component flows are approximately 4,000 mL/min H₂ and 2,000 mL/min O₂; the printed 66%/33% values are rounded and sum to 99%.
Until discharge; median total H₂/O₂ exposure 64 hours and median 7.7 hours/day, versus 24 hours/day conventional oxygen in controls.
More H₂/O₂ participants improved on the disease-severity scale at days 2 and 3 and end of treatment, with improvements in several symptoms and oxygen saturation. No serious adverse events were reported. The treatment and comparator differed substantially in daily gas-exposure duration.
Methods explicitly state there was no randomization, despite the article calling the work a trial and the discussion calling it randomized; open-label clinician assignment creates major selection/confounding risk. Small selected sample, no propensity matching, unequal exposure time, early-pandemic supportive-care variability and outcomes mostly symptom scales. Shanghai Asclepius provided the generator; funding was reported as none, one author was the journal's unpaid editor-in-chief and other authors declared no conflicts.
What kind of evidence is this?
Human
Multicentre open-label nonrandomized concurrent-control study
Respiratory health
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
Hospitalized patients with COVID-19 and dyspnea at enrollment during the early 2020 outbreak in China.
90 analyzed participants: H₂/O₂ n=44 and standard care with oxygen n=46, selected after screening 633 records.
Until discharge; median total H₂/O₂ exposure 64 hours and median 7.7 hours/day, versus 24 hours/day conventional oxygen in controls.
H₂/O₂ inhalation by nasal cannula daily until discharge in addition to standard care.
Brown's gas / oxyhydrogen; the article reports rounded composition of 66% H₂ and 33% O₂, consistent with an approximately 2:1 mixture.
Total flow was 6 L/min. Based on the intended 2:1 Brown's-gas ratio, component flows are approximately 4,000 mL/min H₂ and 2,000 mL/min O₂; the printed 66%/33% values are rounded and sum to 99%.
Approximately 4,000 mL/min, calculated from the reported 2:1 mixture at 6 L/min.
Approximately 2,000 mL/min, calculated from the reported 2:1 mixture at 6 L/min.
Standard care with conventional oxygen therapy; allocation was chosen by attending clinicians, not randomized.
Outcomes and reported result
Five-category disease severity, dyspnea, cough, chest distress, chest pain, resting oxygen saturation and adverse events at days 2, 3 and end of treatment.
More H₂/O₂ participants improved on the disease-severity scale at days 2 and 3 and end of treatment, with improvements in several symptoms and oxygen saturation. No serious adverse events were reported. The treatment and comparator differed substantially in daily gas-exposure duration.
The complete free PMC article and supplement-linked methods were checked for clinician-directed allocation, gas composition/flow, exposure duration, outcomes, adverse events, commercial device provision, funding and conflicts.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Methods explicitly state there was no randomization, despite the article calling the work a trial and the discussion calling it randomized; open-label clinician assignment creates major selection/confounding risk. Small selected sample, no propensity matching, unequal exposure time, early-pandemic supportive-care variability and outcomes mostly symptom scales. Shanghai Asclepius provided the generator; funding was reported as none, one author was the journal's unpaid editor-in-chief and other authors declared no conflicts.
Early-pandemic hospitalized COVID-19 patients with dyspnea; it does not establish benefit against current variants, vaccination-era care or mortality.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 32642277 · DOI: 10.21037/jtd-2020-057
Free full article in PubMed Central.
Complete PMC article, supplement-linked study details and PubMed metadata; full-text extraction checked 9 August 2026.
10 August 2026
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