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Implementing Human Factors Engineering (HFE) Into Medical Device Design

Human Factors Engineering is applying science to improve the user-device interface.   Consideration of the interaction between user and device is essential in the design phase of the development process. 

Preventing Error and Promoting Ease of Use

The goal in any good HFE design is to limit the likelihood of error, enhancing the ease of use of the device and preventing any tampering against safeguards.  As the manufacturer you design your device to operate in a specified manner.  If given the opportunity it is likely that a user will operate the device (either knowingly or unknowingly) in a manner not consistent with the design.  The manufacturer can anticipate user intention and in effect implement “protection” against misuse.  Another inherent reason for misuse is complexity.  Opportunities for mistakes will increase with increasing complexity of device use.  Complexity encourages users to take “short cuts” whenever possible.

Is it a regulatory requirement?

Yes, Human Factors Engineering is stated in the quality system regulation and is something that firms (selling products in the US) must comply with.  The QSR indirectly uses catch all phrases that makes HFE consideration unavoidable.

 "maintain procedures to control and verify the design of the device in order to ensure that specified design requirements are met. Manufacturers are required to establish and maintain procedures:

q       To ensure that the design requirements are appropriate and address the intended use of the device, including the needs of the user and patient, and

q       For verifying and validating the device design, to ensure that devices conform to the users needs and intended uses."

Building your HFE file

In addition to in-house brainstorming, other sources of information are useful for input into your HFE program.  For instance FDA’s MDR database has an inexhaustible supply of incidents related to device-human interaction failures.

Other sources of information that may be useful include FDA’s MAUDE database as well as other hospital incident reporting systems. There are also published standards, scientific technical data, usability tests employing typical users (and perhaps untypical users), clinical evidence, as well as expert advice.

Using Risk Management for Human Factors Engineering

Risk management is an essential element for any Quality Management System.  Applying it systematically helps identify,  understand, control and mitigate potential HFE related hazards.

The following is a step by step analysis of how your HFE program should be implemented.

q       The steps to managing HFE risks begins with identifying and describe use-related hazards related to user-device interactions (see below for recommendations on where to get information).  A list should be compiled of known risks as well as any foreseeable misuse of the device.

q       The next step is to estimate the risk associated with each hazard.  This evaluation can be either quantitative or qualitative, but should stem from the method used in your risk management plan.  This can be a time saver step since some hazards may result in very low risks.  This will effectively direct you to the more likelihood hazards that will require more in-dept analysis and mitigation.  The decision whether the risk requires mitigation or not should be made and recorded.

q       After estimating risk and determining that risk mitigation is required, the next step is to develop strategies and controls to reduce the likelihood or mitigate the consequences of use-related hazard scenarios.  Strategies should consider simplifying product use as well as safe-guarding against alarm tampering.  In essence you are “fool-proofing” use of your product.

q       After estimating various methods of risk control (there may be more than one way to mitigate a risk) select and implement the control strategy. Sometimes the risk can not be mitigated any further than is reasonably possible.  This is the time to determine if the risk is reasonably acceptable and outweighs the benefit of the device.

q       The next step is to ensure that no other risks were inadvertently introduced as a result of implementing the control.  If this is the case, then the new risk needs to be evaluated as we did for each identified hazard.

q       The product specifications (operational and function requirements) need to be re-evaluated to ensure the control measures didn’t change anything.  This step should follow after all hazards have been mitigated – including those that resulted from control measures.  In essence you have thoroughly evaluated your device for risks and have completed implementation of all control measures.

q       The final step is to test and validate the design use – to ensure safe and effectiveness.

Conclusion

Human Factors Engineering is an effective way to systematically test potential user-product interfaces.  It is an off shoot from your Quality Management System’s Risk Management policy. 

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