Hydrogenology
Hydrogenology editorial study record

Hydrogen gas (XEN) inhalation ameliorates airway inflammation in asthma and COPD patients

Wang ST et al. · QJM. 2020;113(12):870–875.

HumanInhaled H₂Published 2020
Study record, not medical adviceThis page reports one source and Hydrogenology’s source-text extraction. It does not establish that molecular hydrogen is effective, safe or appropriate for any person. Human, animal and laboratory evidence must not be treated as equivalent.
Source and classification

What kind of evidence is this?

Evidence stream

Human

Reported design

Prospective uncontrolled before-and-after study

Research topic

Respiratory health

Administration classification

Inhaled H₂

Study result signal

Not reported in this record.

Outcome type

Not reported in this record.

Reported in the source

Methods at a glance

Population or model

Adults with asthma or chronic obstructive pulmonary disease

Sample

20 participants: asthma n=10, COPD n=10

Duration

One 45-minute inhalation session

Intervention

A hydrogen-containing steam/air mixture inhaled once for 45 minutes

Hydrogen form

H₂ in steam/air after device oxygen removal — not Brown’s gas at the point of delivery.

H₂ specification

The generator initially produced 67% H₂/33% O₂, but an oxygen-adsorption cartridge removed O₂ before inhalation. Device gas was about 2.4% H₂ and nasal-cannula concentration about 0.1–0.3%.

H₂ flow

Not reported. Total outlet flow was not provided, so H₂ flow in mL/min cannot be calculated.

O₂ delivered with H₂

O₂ was generated upstream but reportedly removed by a cartridge before inhalation; delivered O₂ flow was not reported.

Comparator

No concurrent comparator

Reported, not endorsed

Outcomes and reported result

Outcomes measured

Blood and exhaled-breath-condensate cytokines

Reported result

Some cytokines decreased, others did not, and one marker increased. No symptom, lung-function or longer-term clinical outcome was tested.

Results-extraction completeness

Gas pathway, concentration, main biomarker results, funding and conflict statement checked in the free full text; flow remains unreported.

A reported association, difference or mechanism is not automatically a clinical benefit. Null findings, outcome type, study design and precision all matter.

Interpretation limits

Cautions and applicability

Design and reporting cautions

Acute uncontrolled study with 10 people per condition and many biomarkers. It cannot establish clinical benefit. Chinese public programs funded the study; authors declared no conflict.

Applies directly to

Adults with asthma or COPD under a single short inhalation protocol.

Preliminary appraisal framework

Not reported in this record.

Preliminary risk-of-bias status

Not reported in this record.

Appraisal rationale

Not reported in this record.

No single-study GRADE certainty rating is assigned. Certainty is assessed by important outcome across a complete eligible evidence set, not by attaching a final grade to one source.

Provenance

Sources and record status

Identifiers

PMID: 32407476 · DOI: 10.1093/qjmed/hcaa164

Publisher access

Open-access article.

Extraction basis

Free full text on PMC and Oxford Academic; identifiers cross-checked in PubMed.

Record revision

2026-08-10

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