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Hong Kong has published a document dedicated to the Medical Device Administrative Classification System (MDACS). The document provides an overview of the applicable regulatory requirements, as well as additional clarifications to be taken into consideration by medical device manufacturers and other parties involved in order to ensure compliance.
At the same time, the document could be subject to changes, should such changes be reasonably necessary to reflect corresponding amendments to the applicable classification rules.
Determination of Device Class
The process of determining the appropriate classification for a medical device is a crucial step for manufacturers. This involves a series of decisions and considerations to ensure that the device is properly categorized according to its intended use, design, and any special features that might place it in different risk classes.
The classification directly impacts the regulatory scrutiny and conformity assessment that the device must undergo before it can be marketed.
Is the Product a Medical Device?
The first step in determining the classification is to establish whether the product in question qualifies as a medical device according to the relevant definitions (as outlined in Clause 3 of the document). It is important to note that devices used for in vitro examination of specimens derived from the human body are not covered by the classification rules described in this document.
Documenting the Intended Use
Once it is confirmed that the product is a medical device, the manufacturer must clearly document its intended use. This documentation forms the basis for applying the classification rules, as the intended use directly influences the level of risk associated with the device.
Applying Classification Rules
The manufacturer must then review all applicable classification rules to determine the appropriate class for the device. If a medical device possesses features that could place it into more than one class, the device should be classified according to the highest class indicated.
This approach ensures that the device undergoes the most stringent regulatory scrutiny applicable to its features and intended use.
Considering Special Rules
Finally, the manufacturer should determine if the device is subject to any special rules that could influence its classification. These rules may address specific types of devices or particular aspects of device use that require additional considerations.
Classification Rules for General Medical Devices
The classification of general medical devices is not a straightforward process and depends on the specific claims made by the manufacturer and the device’s intended use. It is important to mention that while examples are provided within the document to help interpret each rule, the actual classification must be considered on a case-by-case basis, taking into account the device’s design, intended use, and any special features.
Classification Based on Non-Invasive Devices
Rule 1: Non-Invasive Devices Contacting Injured Skin
Non-invasive devices that come into contact with injured skin are classified based on their intended purpose:
- Class I: Devices intended to be used as a mechanical barrier, for compression, or for absorption of exudates, facilitating healing by primary intent (e.g., simple wound dressings, cotton wool).
- Class II: Devices primarily intended for wounds that have breached the dermis and are used to manage the microenvironment of a wound (e.g., non-medicated impregnated gauze dressings).
- Class III: Devices intended for wounds where the subcutaneous tissue is exposed and healing occurs by secondary intent, requiring new tissue formation before closure (e.g., dressings for chronic ulcerated wounds, severe burns).
Rule 2: Devices for Channeling or Storing Substances
Non-invasive devices intended for channeling or storing body liquids, tissues, or gases are classified based on their connection to active medical devices.
- Class I: Devices used for simple channeling or storage (e.g., administration sets for gravity infusion, syringes without needles).
- Class II: Devices connected to an active medical device in Class II or higher, or intended for use with blood or other body liquids (e.g., syringes for infusion pumps, blood bags).
Rule 3: Devices Modifying Biological or Chemical Composition
Devices that modify the biological or chemical composition of blood or other body liquids intended for infusion into the body are classified based on their complexity:
- Class III: Devices performing significant modifications (e.g., haemodialyzers, devices to remove white blood cells).
- Class II: Devices performing simpler modifications like filtration or centrifugation (e.g., particulate filters in extracorporeal circulation systems).
Rule 4: Other Non-Invasive Devices
Non-invasive devices that do not fall into the above categories and either do not contact the patient or only contact intact skin are classified as Class I (e.g., urine collection bottles, compression hosiery).
Classification Based on Invasive Devices
Rule 5: Invasive Devices for Body Orifices
Invasive devices that interact with body orifices, excluding surgically invasive devices, are classified based on their connection to active medical devices and duration of use:
- Class I: Devices intended for transient use (e.g., examination gloves, enema devices).
- Class II: Devices intended for short-term use (e.g., urinary catheters, tracheal tubes).
- Class III: Devices intended for long-term use (e.g., urethral stents, long-term contact lenses).
- Class IV: Devices specifically intended for use in direct contact with the central nervous system (e.g., neurological catheters).
Rule 6: Surgically Invasive Devices for Transient Use
Surgically invasive devices intended for transient use, such as surgical instruments and various catheters, are generally classified as Class II.
However, special considerations may place them in higher classes:
- Class I: Reusable surgical instruments.
- Class III: Devices that administer energy in the form of ionizing radiation, or those with a biological effect (e.g., brachytherapy devices, absorbable sutures).
Classification Based on Active Devices
Rule 9: Active Therapeutic Devices
Active therapeutic devices intended to administer or exchange energy are classified based on the potential hazard:
- Class II: Devices like muscle stimulators and neonatal phototherapy equipment.
- Class III: Devices that may administer energy in a potentially hazardous way (e.g., lung ventilators, surgical lasers).
Special Classification Rules
It is also important to mention that certain devices, such as those incorporating medicinal substances or manufactured from animal or human tissues, are subject to special classification rules, typically placing them in Class IV. These include devices like antibiotic bone cement, heparin-coated catheters, and porcine heart valves.
Conclusion
In summary, the classification of medical devices under the MDACS is a detailed and nuanced process that requires careful consideration of the device’s intended use, design, and any special features that could affect its risk level.
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