Medical Device Classification- Q&As

By Dr William Brambley, Lead Medical Writer, Mantra Systems Ltd

Below we have selected a few common questions which cover a variety of different Annex VIII rules and how they are applied.?

Why are variations of the same device given different classifications??

The classification of medical devices is based not just on the physical characteristics, but also on intended use. A useful example of this is the different types of urinary catheters. Rule 5 governs devices that are invasive with respect to body orifices, dividing devices affected by this rule by their intended duration of use.??

Intermittent catheters that are inserted into the bladder and removed once it is empty would be intended for transient use, and therefore classified as class I.?

Indwelling catheters used for a brief period of time e.g. inserted to monitor fluid balance in an acutely unwell patient would be intended for short term use, and therefore classified as class IIa.?

Long-term catheters such as those for patients with urinary incontinence would be intended for long-term use, and therefore classified as class IIb.?

In addition, devices that are similar may be used in different areas of the body which can lead to different classifications. ?

For example, a removable dental prosthesis would be considered a short-term use device, but as it is only used in the oral cavity is classed as a class I device, not class IIa. Similarly, a fixed dental prosthesis would be considered a long-term use class IIb device, but as it is only used in the oral cavity is classed as a class IIa device. ?

How can body anatomy affect medical device classification??

Some similar medical devices can have different classifications depending on the specific anatomical area used. There are a number of rules with exceptions to this, most commonly involving the heart and central nervous system.?

• Rule 6: Generally, surgically invasive devices intended for transient use are class IIa. However, devices intended for use in the heart or central circulatory system class III. This would mean that a peripheral arterial line would be a class IIa device while an angioplasty catheter would be a class III device. Any device intended for use with direct contact with the central nervous system is a class III. This would mean that a typical venepuncture needle would be a class IIa device whereas a spinal needle would be a class III device.?

• Rule 8: Long-term surgically invasive devices and implantable devices are often class IIb. An exception exists for devices intended for use in the heart or circulatory system (class III). This would mean that although peripheral vascular grafts and stents are class IIb devices, prosthetic heart valves or devices such as intra-aortic balloon pumps would be class III.

What kinds of active devices are there and how does that affect their classification??

Rule 9 governs certain types of active devices. Devices intended to administer or exchange energy are classified as IIa, unless they administer or exchange energy in a hazardous way in which case they are class IIb. The table below gives some examples of such devices.???

How is software as a medical device classified??

Rule 11 is applied to software intended for diagnoses, therapy or the monitoring of physiological processes. These devices are divided into classes based on the potential impact of their function as detailed in the table below.?

It is important to note that if software does not belong to either of those subgroups, it is class I. An example of this could be a statistical algorithm that calculates fertility status based on various health data parameters.?

Are all radiological devices classified the same??

Rule 10 governs active devices intended for diagnosis or monitoring including radiology. As almost all diagnostic radiological devices use some sort of energy that can be absorbed by the human body, they are class IIa devices. Perhaps the most important exception to this is devices which emit ionising radiation which are class IIb.??

This means that CT and X-ray machines would be class IIb devices whereas an MRI machine would be class IIa.??

What classification best fits my wound dressing??

Several different classifications could apply to a wound dressing. Rule 4 governs non-invasive devices which come into contact with injured skin or mucous membranes. Logically these would most commonly apply to wound dressings. The intended use for class I devices under this rule should be “a mechanical barrier, for compression or for the absorption of exudates”.??

Exceptions to this rule are dressings intended for use on severe wounds (typically burns or ulcers) which heal through secondary intent. These would be class IIb. New types of dressings claim to manage the micro-environment of a wound to enhance the natural healing process. These would be class IIa.?

Are all inhaled medication devices classified the same??

Rule 20 governs invasive devices intended to administer medication via inhalation. While most devices fitting this description are class IIa, if their intended use is in life-threatening conditions they are class IIb. An example of an IIb device under this rule would be a nebuliser intended for use in acute exacerbations of COPD, whereas a nicotine replacement inhaler would be class IIa.?

Further Information?

The Medical Device Coordination Group (MDCG) document “MDCG 2021-24 – Guidance on classification of medical devices” is a fantastic resource with further detail and examples relating to the classification of medical devices.?