On August 5, 2014, the FDA published guidance regarding the design of medical devices intended for use in the home . I have written on many occasions how medical devices initially designed for use in hospitals and clinics are now being used in the home. Following is a summary of the most important points contained in the FDA’s guidance.
The guidance focuses on three specific areas to consider when designing medical devices that will be used in a home or other non-clinical setting: the user, the environment and the device.
The objective of the guidance is to help designers develop home-use devices that are safe and minimize the likelihood that an adverse event will occur. The most effective way of doing that is to “design risk out of the device”. The manufacturer has to demonstrate in their premarket submission to the FDA what they did to consider and address relevant hazards and risks.
For purposes of the guidance, home-use is considered to be any environment outside a professional health care facility. Home use could be extended to include use in a school/office/retail environment, on a train/plane/car, etc. The designer should analyze use scenarios in all the environments in which the device could be used, and identify and mitigate risks. Consideration also needs to be given to conditions in which the device could be stored. Questions of heat, humidity, water/fluid/dust ingress and other factors associated with storage and use in a non-sterile environment should be considered.
Specific questions to answer:
- If the device requires a water supply, is well water or treated water permissible?
- Over what temperature ranges will the device be subject to?
- Have variability in dampness and humidity been considered?
- Have atmospheric pressure changes been considered, e.g., for operation in the mountains or during air travel?
- Does the device provide for adequate air flow in the environments in which it could be used?
- Do any provisions need to be made for travel and use internationally, such as electrical adaptors/converters, protection from effects from security screening systems, etc.?
- Is the device interface visible under varying lighting conditions?
Home users have a broad range of physical, sensory, and cognitive abilities. Emotional differences should also be considered, especially with devices designed for users who could be dealing with a new diagnosis or condition and the resultant anxiety.
- Could the user population have visual or other impairments that need to be considered in the design of the device interface?
- What are the cognitive abilities of the user population? Do literacy levels need to be considered? Could users have any type of cognitive impairment?
Design to prevent reasonably-foreseeable misuse. Consider that both children and adults could interact with the device in inappropriate ways. Premarket submission should identify characteristics of the intended user population and how the design was developed to accommodate any physical, sensory and cognitive limitations.
Home-use devices are exposed to more hazards than are present in professional health care facilities and present greater potential for harm caused by user error. The designer should develop a process for identifying potential hazards, estimating and evaluating the risks, controlling the risks and monitoring the effectiveness of the controls. Labelling alone should not be relied on to prevent misuse. Specific items that should be considered in the device design:
- Home-use devices should not rely solely on lock-out mechanisms to prevent harm to the user. Other design solutions should also be considered.
- Minimize the requirements for maintenance to the extent possible.
- Minimize the requirements for calibration of the device. Provide a means to trace calibrated values.
- Design for structural and operational integrity should the device impact the ground or other objects.
- Take into account that environments outside professional health care facilities could have poor electrical grounding and unreliable sources of electricity.
- Outlets in the home could be controlled by wall switches. The user should be warned of this if AC power is required.
- Do provisions need to be made for potential power outages?
- Outside of controlled environments like professional health care facilities, the potential for electromagnetic interference cannot be predicted. To what extent does the device need to be shielded?
- If the device has radio frequency wireless capability it should be tested against common RF wireless technologies expected to be present in the environment of use.
- Alarm systems should be designed with consideration that the home can be a noisy, distracting environment. Users could also have hearing impairment. If a device requires an alarm, the FDA recommends that the alarm signal be provided in at least two of the visual, auditory, and tactile modes.
Human Factors Testing
Usability testing early in the design process and several more times as the design evolves will head off problems that are difficult and expensive to solve at later stages. The FDA recommends that manufacturers conduct a human factors validation study following the “formative” stage of design development.
It is important to recognize that home users might not pay attention to supplied training materials on how to operate the device. They might not understand warnings or the need to calibrate, clean and maintain the device. The guidance suggests that the manufacturer minimize the use complexity of the device and validate the effectiveness of training programs/materials. It is especially important that the manufacturer provide instructions to users on emergency procedures.
Labeling on devices should be able to withstand defacement or wear. Consideration should also be given to situations in which the device could become separated from the labeling.
Home use devices should be designed to be cleaned, disinfected, or sterilized using readily available supplies and simple techniques.
Most of the points in the FDA’s guidance will already be part of manufacturers’ design processes, but the guidance does serve as a useful checklist for ensuring that relevant issues are addressed. The guidance points out what the FDA will expect to be included in premarket submissions. From a high-level perspective, the guidance suggests that devices intended for home use should consider how the context of use differs from that of professional care facilities. The designer needs to consider the device itself, the user, and the varied environments in which the device could be used.