Excluded Subject Matter (8) - Methods of operating medical devices

As covered in our previous articles on excluded subject matter, the European Patent Convention prohibits the grant of patents to "methods for treatment of the human or animal body by surgery or therapy". For this reason, methods performed by, or using, a medical device are typically excluded from patentability. However, there is an important exception to this for methods of operating a medical device, which can be patentable under the correct circumstances. 

The medical method exclusion only applies where there is a step of treatment or surgery covered by the claim. It is perfectly permissible to claim a method performed by a medical device, provided there is no step of treatment or surgery. For this reason, the Boards of Appeal of the EPO have consistently held that a method which is only concerned with operating a medical device, without there being any functional link between the claimed method and effects produced by the device on the body, does not qualify as a method for treatment by therapy or surgery, and is thus not excluded from patentability. 

For example, a method of measuring flow in an insulin pump implanted in a patient has been found by case law to not be a method of treatment by therapy, because there was no functional link between the method claimed and the dosing of the drug administered by means of the device. It was considered that a functional link to the therapeutic effect would only apply where the claim defines a control mechanism in full technical detail which, when embodied in an implanted device for controlled drug administration, clearly determines when and in what volume drug is fed to the body within a specific period. Only then would the controlling action claimed have a functional connection with the quality and quantity of the drug dose and a direct causal influence on the therapeutic effect produced, thus hindering the doctor in the exercise of their professional skill and necessitating the exclusion from patentability. 

In order to identify where a functional link to a therapeutic or surgical effect exists, it can sometimes be helpful to consider what problem the claim addresses. In the above example, the Board of Appeal was satisfied that the problem objectively inferable from the application documents was addressed solely to an engineer designing the device for controlled drug administration and not to a doctor using the finished product. 

The fact that therapy may be happening in parallel to the claimed method is irrelevant. Another example from the case law concerns a method of automatically detecting an occlusion in a downstream fluid line of a medical pumping system, where the downstream fluid line is configured to carry fluid under pressure between a fluid source and a patient. The claimed method comprised steps defined "during a pumping sequence" pumping medicine into the patient. Yet, the claimed method was found allowable and not excluded from patentability, because it only concerned the operation of the device. The Board of Appeal explained that "Of course, during a pumping sequence the patient will receive the medicine and after initiation of the pumping sequence he will receive the medicine as well. However, the experimental and mathematical determination of a possible occlusion in the fluid line has no effect on this steady or initial pumping and does not give the medical doctor any clue as to what should be done in the then ongoing particular therapeutic treatment in the event that the possible presence of an occlusion is indicated, i.e. as to the therapy." 

Claiming methods of operating a medical device can therefore be a useful form of protection in Europe. However, they will require the correct factual circumstances, such that it is clear there is no functional link between the claimed method and the effects produced by the device on the body; which may be challenging to establish. Therefore, when drafting new patent applications, it can be useful to include examples explaining how a method of operating the device can be conducted without any functional link to a therapeutic or surgical effect, even if these are not the primary area of interest for the application. 

This article is a part of our EPO Practice and Peculiarities series. Click here to explore