By Tommy Cooper, Cooper Consulting Service
A common dilemma for early stage medical device companies is their lack of expertise in medical device development. As expected, the development team is busy establishing the company itself while still trying to define the product and answer questions like:
While trying to respond to these questions, the company is being advised of the significant effect documentation, regulatory strategy, and quality management have on company value. This article addresses documentation the company should prepare while dealing with other project startup questions and issues.
Many startups focus on designing proof-of-concept prototypes and operate without a formal quality management system (QMS). They do not have standard operating procedures (SOPs) or formal documentation systems. Even so, they should prioritize the following planning and high-level requirements documents:
These documents define a project’s scope and improve communication between the development team, outside vendors, management, potential users, and investors. They also organize the project and address some issues that may arise as the project begins. Finally, these documents enhance the development team's effectiveness and should not be considered a distraction.
User Requirement Specification (URS) / Product Requirement Specification (PRS)
Depending on the type of product and individual preference, these requirements may be separated into two documents: one focused on the user, and the other centered on the device. Or, they can be integrated into a combined URS/PRS document. This segment of the article describes sections of the URS/PRS.
The scope defines which devices are covered by the specification document. For example, an extracorporeal blood filtering system may consist of three separate assemblies: the flow control unit, the disposable tubing kit, and the blood filtration cartridge. A wireless ECG/respiratory monitoring system may consist of a patient module, a disposable electrode set, and a software application (app) on a mobile device to display the data.
Reference documents should include the list of applicable standards, along with any other feasibility reports and the user requirements overview. The list of applicable standards — to be covered in a later article in this series — should be maintained as a separate document. For now, here is a quick overview of some sources for the list of applicable standards:
A list of any abbreviations should also be included in the reference documents section.
Intended use is specifically referenced in FDA regulatory applications and determines how the device will be classified and treated by regulatory agencies. A good way to draft the intended use statement is to use the FDA 510(k)/De Novo/PMA summary from a similar product. The associated databases for the summaries — the 510k Database, the De Novo Database, and the PMA Database — are available online.
A good initial approach is to select predicate devices similar to the product and to incorporate their intended use into your requirements document. In submitting a 510(k), the goal is to match the predicate device’s intended use as closely as possible. For the De Novo route, it will be necessary to prove why your device is not substantially equivalent to other similar devices, and to indicate why your device is not Class III. A PMA (Class III) submission will require knowledge of any alternative practices or procedures for diagnosing, treating, preventing, curing, or mitigating the disease or condition for which the device is intended, since there is not a substantially equivalent device.
Before talking with investors or making external presentations, it may be helpful to discuss the product with a few regulatory professionals to make sure your early regulatory strategies are plausible. If the product is designated for non-510(k) pathways, the regulatory process will be more expensive and will require additional submission material. However, this could offer a unique market advantage, in that 510(k) devices already have "substantially equivalent" competitors, while De Novo and PMA devices do not.
Note: When you are identifying similar devices, make sure to save a copy of their submission summary, their FDA classification product code, and their regulation number.
The classification of the medical device per IEC/EN/ES 60601-1 — the basic safety and essential performance standard — is identified in this section. The primary categories are:
These classifications relate to how the equipment is used and to safety testing requirements. Some medical device standards may require specific classifications; for instance, a Type CF applied part with defibrillation protection is designated in the ECG standards. Knowing these classifications early in the development process assists with device design decisions.
Devices need specifications for operating conditions and storage/transport conditions, based on the intended use environment. Below is a standard set of operating, storage, and transport conditions that would cover a range of use environments.
The operating environment is based on factors including the ratings for selected components, the specifications for competitive devices and, most importantly, the actual environment for your device. For example, if you expect to sell the unit worldwide, some countries may have significant populations in higher altitudes, requiring more stringent dielectric withstand specifications.
Remember, these are system operating requirements and the temperature inside your device enclosure may be much higher than the ambient temperature due to heat dissipation in internal components. A higher upper operating temperature may be necessary for EMS use outdoors, or for use in hospitals without air conditioning. Batteries are particularly sensitive to high temperatures — which can reduce battery life and cause battery swelling/leaks — and to low temperatures, which can reduce battery capacity.
Additionally, specialized storage and transport requirements may lead to special handling procedures for carriers; a wide temperature range covers conditions that might be encountered when a device is in a shipping truck during a hot summer day or a cold winter day. If the device cannot withstand a range of temperature or humidity conditions during shipping, it may require special packaging and physical indicators, or special handling instructions, resulting in higher shipping costs.
Likewise, some devices may be affected by shock or vibration and need special protective packaging to ensure that shock limits have not been exceeded. Batteries may require special handling, too, as certain batteries cannot be shipped by air (due to the changes in pressure) or may be damaged by high temperature. For example, a biological absorptive material may be less efficacious if exposed to conditions outside a specific, narrow range.
Defining use environment means answering the following questions:
Different user group profiles for the medical device must be defined to indicate users’ mental, physical, and demographic traits, as well as any special characteristics, such as occupational skills, job requirements, and working conditions. User groups may be separated as patients, physicians, nurses, medical technicians, service technicians, biomedical technicians, home caregivers, and others.
The attributes by which these user groups are separated — such as age, culture, expertise, or type of interaction with the device — may influence device design requirements. Key user group parameters that must be defined include:
This section presents the device usage and major components at a high level and includes a block diagram of the system’s major components (Fig. 1). If the device features different configurations or different use modes, they can be diagramed and explained in this section. This section should make the device operation and components understandable to non-technical individuals, such as investors, executives, and regulatory personnel.
General Design Requirements
In this section, general requirements for the system’s design, operational phases, and usability requirements are described. General design requirements cover a range of system features. For example:
System Operational and Usability Requirements
These requirements usually focus on phases of system usage, such as power-on test, setup and initialization, therapy delivery, post-therapy, and storage. Here are example requirements:
Note: There can be overlap between general design requirements and system operation requirements. It is not a black-and-white divide, but two different ways of thinking through high-level requirements.
Performance requirements define quantifiable specifications that are testable. A particular sub-component or sub-system that will not have separate component requirements may be specified in this section. Here are some examples:
User Interface Requirements
User interface (UI) requirements should specify all UIs on the device to guide the usability plan’s outline. UI requirements can include things like hard keys, indicators, graphical user interface, and transport/wear interfaces. Here are some examples:
Labeling, Packaging, Transport, and Storage
Labeling requirements will vary depending on potential markets. Here is the basic information included on device labeling:
Depending on risk management mitigations, usability studies, EU MDR requirements, FDA guidance, and other (i.e., country specific) standards, additional labeling may be required. The product labeling material must withstand durability and environmental testing, and the text must be “clearly legible,” according to standard definition.
In addition to device labeling, device packaging requires labeling. This labeling contains similar information to the device labeling but includes transportation-specific information:
Depending on the transport environmental specification, rough handling limits, and device components, packaging may require features like humidity protection or sensors to detect whether a force limit has been exceeded. If the device is sterile, the packaging will have to pass standards testing and have a specified shelf life for sterilization. If a device requires limitations on transportation environment, it may require special handling for storage and transport, such as temperature-controlled storage, ground/sea transport only, and/or flammability precautions.
These requirements usually are focused on manuals that will be needed (e.g., operator and service/install), whether the manual will be paper-based only or both paper-based and electronic (on the device), and languages into which the manual will be translated. Depending on the user’s education level and UI complexity, the user manual may require videos. Note that EU MDR requires electronic manuals.
These requirements indicate how the company will train users and service personnel. For example, service staff and application specialists will be required to attend training courses at the company, while medical staff may be trained by the application specialists. This documentation also identifies what training materials need to be developed.
Depending on the device’s target market(s), disposal requirements may differ significantly. A common theme for specialty disposal is that local regulations should be followed for batteries. It also is common that materials used in the machine should be recycled if possible.
If the device will be marketed in the EU, disposal requirements will include compliance to the Restrictions on Hazardous Substances (RoHS) and the Waste Electrical and Electronic Equipment (WEEE) directives. ROHS also applies to devices that will eventually be marketed in China and other countries.
The URS/PRS is a key document in the product development process and should be prepared and released during the product’s initial development phase. For simple projects, this documentation may be prepared in the first few months. For complex products with several subsystems, it may take up to a year to draft and approve the URS/PRS.
The effort to prepare this document will clarify device features and key performance characteristics. Having this document, along with the others listed at the beginning of this article, will add value and organize the product development process, an important factor in the success of any startup.
About The Author
Tommy Cooper, PE has a BSEE ’74 and MSEE ’81 from University of Houston. He has worked in the medical device industry for over 40 years. He served 12 years as the co-chairman of the AAMI Blood Pressure Transducer Committee, holds 22 patents in the field of medical devices, and has published more than 16 articles in professional journals. He has developed numerous medical devices from concept phase to regulatory approval and production. Tommy founded Cooper Consulting Service (CCS) — an engineering design and development company with a focus on medical devices located in Friendswood, TX — in 1986.