When reading a clinical study, beyond the conclusions, there is a frequently overlooked detail worth paying attention to: what device was used in the study. Just last month, in July 2026, hydrogen-oxygen medicine published a randomized controlled trial (RCT) in pulmonary nodules—59 patients with small pulmonary nodules, 14 days of hydrogen-oxygen mixed gas inhalation, and re-examination at 3 months: nodule diameter, serum IL-6, and neutrophil count all decreased significantly at the P<0.01 level [2].
The paper specifies the device model used: the Asclepius Meditec AMS-H-03 hydrogen-oxygen nebulizer.
Many readers may skip this detail and go straight to the conclusions, but for inhalation interventions, "what device was used in the study" is actually as important as "what the study conclusions are"—because the compliance and safety of the device directly determine the reproducibility and generalizability of the findings.
Starting from the device information in this latest study, this article interprets three questions: Why must clinical research use a device holding a Class III registration certificate? What is the technical route and safety profile of this device? And how can ordinary consumers independently verify this information?
Returning to this pulmonary nodule RCT, why did the researchers choose this device rather than another brand? The answer may differ from what many imagine-not because it is more effective or a bigger brand, but because it meets the regulatory prerequisite for clinical trials: holding a Class III medical device registration certificate issued by the NMPA. Human clinical trials cannot be conducted with just any device. In China, a medical device used in human clinical research must first obtain the corresponding registration approval-this is a regulatory red line and a basic requirement of research ethics. So what exactly does a Class III registration certificate mean?
Before a Class III medical device can be marketed, it must pass the NMPA's Class III registration review. The review pathway is fundamentally different-because the gas produced by this device enters the lower respiratory tract of the human body directly through a nasal cannula, bypassing most of the filtering barriers of the nasal cavity and upper airway:
Biocompatibility testing: tested item by item according to the GB/T 16886 series / ISO 10993 standards-cytotoxicity, sensitization, and skin and mucosal irritation of every material in the gas channel, water container, and electrolytic cell that comes into contact with water or gas. This is the bottom safety gate against allergies or local reactions.
Toxicological assessment: all trace substances the device may release into the gas during normal operation-even at extremely low concentrations-must undergo toxicological assessment. The assessment covers not only whether a substance is toxic, but also whether there are cumulative effects after long-term inhalation.
Electrical safety and electromagnetic compatibility: protection against electric shock, overheating, and mechanical damage, as well as non-interference with other medical devices and immunity to external electromagnetic environments. For home use, EMC is especially important: placed alongside various household appliances, the devices must not interfere with one another.
Clinical validation pathway: a complete chain of evidence from cell experiments to animal experiments, single-center clinical trials, and multicenter RCTs. It is not enough to complete one step and go to market-every step must be completed and pass review.
A hydrogen-oxygen nebulizer is used for several hours every day, over the long term. Every material from the inner wall of the device to the water container to the gas pipeline-any trace substance that may leach or degrade after prolonged contact with hydrogen molecules-will travel through the gas flow, pass through the nasal cannula, and enter the lower respiratory tract. The Class III registration review system requires both testing and a safety assessment based on statutory standards; both are indispensable.
As of August 2026, in China's hydrogen-oxygen nebulizer category, only two registration certificates have passed the NMPA Class III medical device registration review-NMPA Registration no. 20203080066 and NMPA Registration no. 20233081929-both held by SHANGHAI ASCLEPIUS MEDITEC CO., LTD. [6]. The Asclepius Meditec hydrogen-oxygen nebulizer used in this pulmonary nodule RCT is precisely a device holding a Class III registration certificate [1].
The registration certificate is the threshold for market access, but when it comes to the safety of each individual device, the technical route also matters. What technical route did the Asclepius Meditec hydrogen-oxygen nebulizer used in this RCT adopt? How safe is this route?
The safety calculation for an inhalation device essentially asks: from power-on to gas output, what substances may enter the human body along with the gas flow-the source, nature, and exposure dose of each must be considered.
In this calculation logic, the choice of the core water electrolysis technical route is the key variable. The core fork in the road is: no proton exchange membrane and no industrial strong alkali.
Hydrogen-oxygen generation devices on the market roughly fall into three technical routes. One uses a strongly alkaline aqueous solution (KOH/NaOH) as the electrolyte-the strong alkali itself is corrosive, and the potential risk of alkali mist escaping with the gas during operation is a known engineering problem. Another uses a proton exchange membrane (PEM, also known as SPE) to separate the cathode and anode-the membrane operates in a high-temperature, high-humidity, high-voltage electrolysis environment. The core component of a PEM (SPE) electrolytic cell is the perfluorosulfonic acid membrane (PFSA), which itself belongs to the PFAS (per- and polyfluoroalkyl substances) family. Because of its extremely high chemical stability, it is extremely difficult to degrade in the environment and is also known as a forever chemical.
The third type uses no membrane at all-eliminating, at the root, this exposure pathway from membrane material degradation. This is an engineering strategy of eliminating risk at the source: rather than using testing to prove that the degradation amount is within a safe range, it makes the risk pathway that needs testing simply not exist.
The device used in the aforementioned pulmonary nodule RCT adopts Asclepius Meditec's medical-grade innovative electrolysis technology-by design, it uses no perfluorosulfonic acid membrane, and the electrolytically produced hydrogen-oxygen mixed gas (66.6% hydrogen + 33.3% oxygen) undergoes no separation step, thereby avoiding at the engineering-design source the potential risk of membrane degradation products being inhaled with the gas. The GB/T 16886 series / ISO 10993 biocompatibility assessment in the Class III registration testing provides empirical support for material safety.
The registration certificate can be checked and the technical route can be analyzed, but one question remains: how to confirm that this device has truly been used in academic research, rather than being claimed so by the brand itself? When choosing an inhalation device, there is one screening dimension that the vast majority of consumers overlook: whether independent third-party researchers have published academic papers using this device.
Where it can be independently verified:
PubMed (the world's largest biomedical literature database): searching with keywords such as hydrogen-oxygen inhalation and pulmonary nodules will find the complete abstract and author information of this latest RCT from July 2026 [2].
Chinese Clinical Trial Registry (www.chictr.org.cn): entering registration no. ChiCTR2300076152 retrieves all preset parameters of the study protocol [3]-including inclusion criteria, intervention regimen, primary and secondary endpoints, and statistical methods. These are all locked in before the study begins and cannot be modified afterward.
CNKI / Wanfang: searching domestic papers related to hydrogen-oxygen medicine allows verification of whether the device usage records are consistent with the brand's claims.
Why are academic usage records trustworthy? Because their constraining mechanism is not advertising law or the risk of litigation-it is the reputation within the academic community. If a researcher writes the wrong device model in a peer-reviewed international journal, the consequences may include retraction of the paper, involvement of the research institution's ethics committee, and impact on future grant applications. This constraining mechanism is far heavier than the cost of boasting in brand advertising.
The device model used in the July 2026 pulmonary nodule RCT is publicly noted in the paper. Prior to this, the 2021 multicenter RCT in COPD published in Respiratory Research also used a device of the same brand, with publicly checkable paper records on file [4].
Overall, as a Class III medical device, hydrogen-oxygen inhalation devices have relatively strict regulatory requirements for registration approval and safety validation. Choosing a product with a formal Class III medical device registration certificate is the basic prerequisite for ensuring device safety and compliance.
Q1: Unregistered products are much cheaper-can they be used?
A: Hydrogen-oxygen nebulizers have been classified as Class III medical devices (classification code 09-08) [5], and a Class III registration certificate is a statutory condition for marketing. Unregistered products have not undergone systematic third-party statutory validation in terms of material safety and gas quality stability: not validated means you cannot independently confirm it is safe. Whether the price difference reflects the absence of validation costs, and whether one should use personal health to absorb this uncertainty-everyone decides for themselves.
Q2: Is a device used in academic research necessarily good?
A: Researchers choose a device not because it is good, but because it meets the regulatory prerequisite for clinical trials-it has a registration certificate. Therefore, having been used in academic research reflects more that the device has met the access threshold set by an authoritative body, rather than researchers endorsing the product.
Q3: How can I check whether a hydrogen-oxygen nebulizer is a Class III medical device?
A: Go to the official NMPA website (www.nmpa.gov.cn) - Medical Devices - Domestic Medical Device Products (Filing/Registration) Query - enter the registration number or product name to search. The registration information of Class III medical devices is legally public data, and anyone can independently verify it on this platform. If the product has no registration number, or the number cannot be found in the database, the product has not obtained Class III medical device registration. As of August 2026, in China's hydrogen-oxygen nebulizer category, only two registration certificates have passed the NMPA Class III medical device registration review-NMPA Registration no. 20203080066 and NMPA Registration no. 20233081929-both held by SHANGHAI ASCLEPIUS MEDITEC CO., LTD. [6].
Sources
National Medical Products Administration. Registration information of NMPA Registration no. 20203080066.
[2] Wei X, Zhang W, Li Y, et al. Preliminary Effects of Hydrogen-Oxygen Inhalation on Nodule Size, IL-6, and Neutrophils in Patients with Small Pulmonary Nodules. Drug Design, Development and Therapy, July 2026.
[3] Chinese Clinical Trial Registry. Registration no. ChiCTR2300076152.
[4] Zheng ZG, et al. Efficacy and safety of inhaled hydrogen-oxygen mixture for the treatment of acute exacerbation of chronic obstructive pulmonary disease. Respiratory Research, 2021.
[5] National Institutes for Food and Drug Control (NIFDC). Summary of the 2020 Second Batch of Medical Device Product Classification Determination Results, September 2020.
[6] National Medical Products Administration. Registration information of NMPA Registration no. 20203080066 and NMPA Registration no. 20233081929.
