Medical Gases: An Overview

What are Medical Gases?

Medical gases generally refer to any gases or mixtures of gases intended for medicinal uses. Common examples are oxygen, nitrogen, nitrous oxide (commonly known as “laughing gas”), nitric oxide, carbon dioxide, helium, medical air and mixture of some of the above gases. They can be stored in gas cylinders, gas tankers, stationary cryogenic storage tanks or transportable cryogenic tanks.

How are Medical Gases Used?

Medical gases are used for a number clinical applications with their therapeutic, prophylactic or diagnostic properties. Below are examples of their clinical uses.

1. Medical oxygen: Used for the treatment of acute severe asthma, pulmonary thrombo-embolism, pneumonia and fibrosing alveolitis by inhalation;
2. Medical carbon dioxide: Used for the prevention of hypocapnia during hyperventilation by inhalation;
3. Mixture of carbon dioxide and oxygen: Used for physiological investigations by inhalation.

Where Medical Gases are used?

The majority of medical gases are being used in Hospital Authority, private hospitals and day procedure centres. Other premises, including clinics, veterinary clinics, nursing homes, residential care homes for the elderly and some households with home-bound patients are also having medical gases for their patients’ use. In addition, Fire Services Department also uses oxygen in cylinders for life saving and daily operation.

Regulations of Medical Gases outside Hong Kong

To ensure the safety, quality and efficacy of medical gases when they reach the patients, international guidelines for regulating gases intended for medical use have been formulated by organisations, such as the European Union (EU) and the Pharmaceutical Inspection Co-operation Scheme (PIC/S).

Some gases intended for medical use are regulated as medicines in the Mainland China and some of the overseas countries, such as Australia, Canada, EU, the United Kingdom and the United States. Regulatory controls cover the requirements for marketing authorisation of the medical gas products, and through adopting the Good Manufacturing Practice (GMP) to control their manufacture. Furthermore, sales restrictions are imposed on these medical gases in accordance with their intended use, ranging from those products available “over-the-counter” to those supplied only under prescription.

In view of increasing demand for medical gases, in particular the use of oxygen in the treatment of patients with Coronavirus disease (COVID-19), the World Health Organization (WHO) has also called attention to the standards on production, control, storage and distribution of medical gas products, and published a guidance for GMP for medicinal gases in 2022.

Controls of Medical Gases in Hong Kong

In Hong Kong, the existing statutory regulations focus on the safety regulation of the manufacture, storage and conveyance of gases which are not specific to medical gases. The Office for Regulation of Private Healthcare Facilities (“ORPHF”) of the Department of Health (“DH”) has issued a Code of Practice for Private Hospitals and a Code of Practice for Day Procedure Centres (“the Codes”) to provide practical guidelines on the installation and operational management of medical gas supplies in private healthcare facilities. The Codes also specify requirements of the medical gas pipeline systems, as well as the operational management of medical gases supplied in compressed gas cylinders and liquid gas containers.

With an aging population and increase use of medical gases, especially during the COVID-19 pandemic, enhancing the control of medical gases in terms of manufacturing, storage, sales and distribution is essential to ensure the medical gas products administered to patients are of suitable quality and with a positive benefit-risk balance.

In June 2024, the Pharmacy and Poisons Board of Hong Kong (the Board) has endorsed to regulate medical gases as pharmaceutical products under the Pharmacy and Poisons Ordinance (Cap. 138) (the Ordinance). The new regulatory control will come into effect on 14 June 2026.

The scope of the regulatory control of medical gases covers any gases or mixtures of gases in cylinder that fulfil the definition of pharmaceutical products as stipulated under section 2 of the Ordinance, which may cover medical gases including oxygen, nitrogen, nitrous oxide, nitric oxide, carbon dioxide, helium, medical air and mixture of some of the above gases, except:

1. Gases that do not achieve their mode of action by pharmacological, immunological or metabolic action in human beings or animals;
2. Gases that are produced in situ in healthcare facilities, i.e. manufactured, mixed and handled in hospitals or day procedure centres for their patients’ own use;
3. Bulk liquefied gases in tankers or vessels (e.g. Vacuum Insulated Evaporator) (Note: Manufacture and supply of such gases are subject to the requirements of Good Manufacturing Practice (“GMP”) Guides issued by the Board. Please refer to the website of the Board (www.ppbhk.org.hk) for the current version of the GMP Guides);
4. The equipment attached later to the gas container at the time of use (e.g. pressure regulator and pipe network);
5. Gases specified for non-medicinal use such as in laboratories (e.g. for calibration), oxygen mixtures for smoke-helmeted firemen, oxygen mixtures for divers during normal diving and ascent, etc.;
6. Oxygen that is produced via generator or concentrator to be used at patient’s bedside; and
7. Gases that are used in pulmonary function tests to measure gas transfer in the lung.

When the new regulatory control takes effect, the pharmaceutical products of medical gases have to be registered with the Board before they can be legally sold or supplied in Hong Kong. In addition, traders of the pharmaceutical products must obtain relevant licence(s) from the Board before conducting manufacture and wholesale (including import and export) of pharmaceutical products, and retail sale of pharmaceutical products containing poisons.

For more information on the registration of pharmaceutical products and licensing of traders, please visit the website of the DH’s Drug Office (https://www.drugoffice.gov.hk/eps/do/en/pharmaceutical_trade/guidelines_forms/useful_guidelines_forms.html).