Clinical Engineering Role During Device Development
A course requirement for BME 274, Regulatory, Clinical & Manufacturing Aspects of Medical Devices taught by Professor Folarin Erogbogbo (Prof.Eros). Please feel free to provide any feedback.
The primary function of the clinical engineer is to relay information between the engineering team and clinicians who will later use the device. They ensure that the customer feedback is incorporated into the device design. The clinical engineer must also aid the design process by acting as the product expert within the company. Clinical engineers are involved with the ideation, concept development, product development, verification and validation, and market introduction phases of the device development process, and can be referred to as product development engineers or clinical development engineers.
Ideation
The Food and Drug Administration (FDA) promotes a device design process called the waterfall. The figure below outlines the steps in this process. The first step in the waterfall design process is the identification of user needs. The main goal of the clinical engineer during this phase is to gather and record all relevant user needs and customer requirements. Sources for this information can be user feedback from patients, physicians, or other hospital staff. They can also perform a market needs assessment to quantify the gap or problem the device is solving. A clinical engineer should also conduct discussions with Key Opinion Leaders (KOLs), which are people that have expert knowledge in the appropriate field. They are recognized as an authority and can make claims about the particular field of study.
Once the user needs and customer requirements have been identified, it is now the job of the clinical engineer to concisely document all of the information. The user needs will be compiled in a list format and every item should be:
- Necessary
A user need is necessary if the system becomes deficient following the removal of the requirement.
- Verifiable
They should be verifiable because it allows for passing criteria during inspection, analysis, or demonstration throughout the verification stage.
- Unique
User specifications should be unique to prevent any redundancy in the specification document.
- Achievable
The factors that contribute to a user need being achievable are cost, time, and other constraints such as available manufacturing techniques.
- Traceable
The user needs should be traceable throughout the specification, design, and testing process to ensure the user need is not lost during device development.
- Clear
Clearly written requirements are essential because the need cannot be taken into consideration if nobody on the engineering team understands what it is.
The endpoint of collecting user needs is that the device should provide user gains and reduce user pains, while not creating any negative impacts to the user operating procedure.
Concept Development
The concept development stage includes the evaluation of different scenarios that the device could be used and the creation of multiple prototypes.
During this stage the clinical engineer should assist in the creation of design requirements, which are based on the user needs. Multiple design requirements can be created to address one user need, as long as they are not redundant. The testing of design requirements are considered as part of the verification phase.
Clinical engineers spend extensive hours learning about the device by talking to KOLs and watching the current procedure methods. They are knowledgeable about the user interface, the technology, and the use environment. They are also responsible for being up-to-date with any advances or changes within the field or market. These engineers will use this information as subject matter experts (SME) to help guide the design requirements. While creating the design requirements, the clinical engineer can also ensure that the device will be versatile enough to handle different use cases that are most possible.
Product Development
The two main areas of product development are function testing and human factors testing.
Functional testing evaluates how the device will operate in potential use scenarios and includes:
- Bench test models
- Cadaver models
- Animal models
- System/Device use workflow
- Setup and teardown procedures
The decision between bench, cadaver, or animal tests depends mainly on the variable being studied. If the team only wants to evaluate how the device fits within human anatomy, a bench test can be performed with a model of the body region. If something like visibility through human tissues will be studied, the team can use a cadaver. A cadaver test does not have to include the entire body and can use only a portion. Animal models can be used to test variables like biocompatibility or thrombogenicity. Biocompatibility is how the device interacts with living tissues. Thrombogenicity is the likelihood that the device will cause the blood to clot.
The level of involvement of the clinical engineer with each test type is dependant on the structure of the company. However, the clinical engineer has the most knowledge about factors that would affect user workflow and setup/teardown procedures. Some examples of these are how much equipment can fit in the user environment and any necessary protocols that must be performed before or after the device. The clinical engineer must also update the user needs based on the results of these tests.
Another factor of product development that the clinical engineer helps perform is human factors testing. It is equally important to prove that the device uses human factors and that the device functions properly. Human factors testing consists of identifying intended users, device use environment, user interfaces, critical tasks, and known issues.
Defining the intended users of the device is important because the level of medical knowledge and previous biases is beneficial to understanding how the device will be received.
The device use environment may include factors such as available lighting, level of distractions, and background noises. These may all affect the ease of the use of the device and, in some cases, alter the effectiveness.
A user interface is any point of interaction between the user and the device through touch, sound, sight, etc. The ideal device would have minimal user interfaces to reduce the amount of user training and minimize the chance of user confusion. Formative evaluations use preliminary analyses concerning safety to improve the user interface design.
A critical task is defined as a task that if it was not performed or performed incorrectly, it would result in harm to the patient.
Known issues with predicate devices can be found through an FDA database, published literature, of user feedback. The FDA database that stores all reported events is called the Manufacturing and User Facility Device Experience (MAUDE) database, and can be specified to a product problem, product class, or event type for a certain time period. The period of time to search for adverse events depends on how often the device is used. Sutures are used very frequently and would only need a short time period, as compared to an artificial eye, which would require a much longer search period. Published literature may provide entire studies for problems that arise with certain device. User feedback is crucial because it fills in any missing perspectives that are missing from online databases or literature.
An important concept to keep in mind when performing human factors testing is that “use errors” are acts that result in a medical device response that is either not expected by the user or unintended by the manufacturer. This terminology helps to remove blame from the user if the device does not perform as expected.
Verification & Validation
Verification is the confirmation by objective evidence that the design output meets the design input. It is the job of the clinical engineer to create procedures for design verification that confirm test results through measurable means and to record all information and data in the Design History File (DHF).
Validation refers to establishing objective evidence that specifications meet the user needs and intended uses. Validation procedures created by clinical engineers should include defined operating conditions, batches to be tests, and simulated use conditions.
Clinical engineers contribute most to validation because it concerns user needs. They ensure that validation testing is performed in user conditions and generates a risk analysis. The risk analysis is a necessary step in the design process and also provides a possible comparison between the newly developed device and its predicates.
As mentioned previously, the clinical engineer is also involved in designing the validation plan. This includes defining the regulatory strategy, how each requirement will be tested, test models, justification for chosen test models, handling of failures during the test, acceptance criteria, and labeling.
Market Introduction
Once the device design is finalized and successfully tested, the clinical engineers help provide marketing claims. This is mainly objective performance results that prove that the device is better than predicate devices.
Following the device launch, clinical engineers work directly with users to improve their experience. Clinical engineers may travel to sites to ensure that users are operating the device correctly. They may also determine areas of improvement for the device based on an analytical understanding of the needs of the users. Then, the clinical engineer can go through the stages of development for the next version or generation of the device.
References
- Sarika, P. (2019) Clinical engineering role & responsibilities in DDP [Powerpoint slides].
- Key Opinion Leaders - What are KOL's and Why Should You Care? (2019, February 21). Retrieved December 12, 2019, from https://influencermarketinghub.com/key-opinion-leaders-what-are-they-and-why-should-you-care/.
- Reh, F. J. (2019, June 1). What Is a Subject Matter Expert and What Do They Do? Retrieved December 12, 2019, from https://www.thebalancecareers.com/subject-matter-expert-2275099.
