Hydrogenology editorial study record

The combined use of inhaled nitric oxide and molecular hydrogen in patients with post-COVID-19 syndrome

Pozdnyakova DD, Baranova IA, Selemir VD, Medvedev OS, Chuchalin AG. · Ter Arkh. 2026;98(3):147–153.

HumanInhaled H₂Published 2026

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

Randomized open-label controlled study

Research topic

Long COVID

Administration classification

Inhaled H₂

Study result signal

Positive signal for selected combined-intervention outcomes; indeterminate for H₂ alone.

Outcome type

Patient-reported, functional, laboratory, microcirculatory and safety outcomes.

Reported in the source

Methods at a glance

Population or model

Adults with post-COVID syndrome.

Sample

60 participants; three groups of 20.

Duration

10 days.

Intervention

Combined inhaled nitric oxide and H₂ for 90 minutes daily.

Hydrogen form

Inhaled H₂-containing gas combined with nitric oxide.

H₂ specification

H₂ below 4%, nitric oxide 60 ppm, total flow 4 L/min.

H₂ flow

4 L/min total gas flow.

O₂ delivered with H₂

The combined gas protocol is reported in the linked full text.

Comparator

Inhaled nitric oxide alone and control care.

Reported, not endorsed

Outcomes and reported result

Outcomes measured

Symptoms, six-minute walk distance, laboratory markers, microcirculation and adverse events.

Reported result

Some symptoms, functional and laboratory measures favored the combined group; no serious adverse events were reported.

Results-extraction completeness

The full article methods, intervention, outcomes, positive and null findings, funding and conflict statements were checked.

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

Open-label, small groups and a combined nitric-oxide/H₂ intervention without an H₂-only arm.

Applies directly to

The studied post-COVID population and combined protocol only.

Preliminary appraisal framework

Cochrane RoB 2 — preliminary

Preliminary risk-of-bias status

High risk

Appraisal rationale

Randomization was reported, but open-label assessment, small groups, multiple outcomes and absence of an H₂-only arm limit interpretation.

Appraisal domains

Random sequence reported or described · Allocation concealment not fully established · Deviations and co-interventions checked · Outcome measurement checked by endpoint · No outcome-level protocol comparison completed

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: 41859790 · DOI: 10.26442/00403660.2026.03.203537

Publisher access

A free publisher or repository full article was checked.

Extraction basis

Publisher or repository full article and bibliographic record; checked 10 August 2026.

Record revision

2026-08-10

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