Medical devices have a direct impact on the lives of patients. To deliver superior and safe experience to patients, medical device manufacturers are continuously innovating their devices using software. However, software come at the risk of defects and bugs.
Medical devices have a direct impact on the lives of patients and a single functional failure can mean the difference between life and death. To reduce unacceptable risk to patients, the medical industry is continuously innovating devices that enable better communication and performance. The World Health Organization has recommended to all governments worldwide to make national regulations for medical devices to provide assurance that devices will offer necessary risk reduction required to minimise harm in the event of a malfunction.
Medical devices’ testing is required to detect the risks and effects of various environmental conditions. Safety assessment focuses on the reliability of products to function correctly and safely in response to inputs. It focuses on potential hazards from mechanical, electrical and environmental aspects of a design occurring during usage. Lifecycle, performance, compliance, interoperability and reliability testing are conducted to verify and validate medical systems and their applications.
Medical device testing strategy
Medical devices are continuously regulated by multiple regulatory bodies for compliance to ensure their better performance and effectiveness. It is better to ensure compliance and conduct technical tests throughout the development cycle, starting from concept and design phase to production stage.
An effective medical device test strategy includes product and technical testing of components, sub-assemblies and the finished product. It correlates defects to optimise overall performance of the device and desired output for each stage. The system is divided into small blocks to test specified requirements for each block in the system. A risk-based approach validates hardware, software and peripheral devices’ testing associated with the intended use of the system.
Cigniti Technologies, a software testing company, follows a five-step testing approach (Fig. 1), which is aligned with the development of product lifecycle, enabling a better understanding of test requirements.
Software validation and verification
End-to-end testing, certification and evaluation help ensure the conformity of the electrical or electronic equipment’s safety and other essential performance requirements for global product approvals. Lynne A. Dunbrack, research vice president, IDC Health Insights, says, “If not properly secured, medical devices, such as bedside telemetry or implantable devices like pacemakers and insulin pumps, can introduce malware to the network.” To mitigate these problems, software validation testing is required, which includes the following:
Interoperability of devices
There is a need for rigorous testing of devices and applications that interoperate and connect to deliver the required experience to the user. This ensures data security and privacy through a quality assurance plan. Tests are recorded and repeated for audit and compliance purposes. For example, if a wearable and its applications do not work in sync, it might not show accurate results. With innovations around Internet of Things (IoT) and smart devices, a need arises for devices, software control and application to integrate with the core software.
Functional validation of software
An application that helps patients or doctors to generate or access reports with a secure log-in must be functional all the time to deliver the required service accurately.
Security of applications
Security testing helps make applications hack-proof and sustainable in the challenging digital scenario. Validation and authentication of user log-ins, testing against firewalls and encrypting user data are some key measures. Healthcare applications or products need to adhere to the stringent Health Insurance Portability and Accountability Act requirements that ensure protection of patient health information.
Regulatory requirements for medical equipment
IEC 60601-xx standard family is the base for the approval procedure of medical electrical equipment in most regulatory frameworks worldwide. Product safety requirements for electrical active medical devices are documented and internationally harmonised under this standard. It is a series of technical standards that ensure the safety of medical electrical equipment.
IEC 60601-1 edition 3 is the internationally-harmonised safety standard used for all electronic medical devices’ safety evaluation. According to this, medical devices are evaluated against electrical shocks, mechanical hazards, unwanted and excessive radiation, ignition hazards, abnormal operation, and faults and constructional defects.
IEC 60601-1 edition 3.1 ensures that electrical, mechanical or functional failures shall not pose any risk to patients and operators. It is recognised as a prerequisite for the commercialisation of electrical medical equipment in many countries. It is the newest published general standard with around 1500 single specific requirements.
IEC 60601-1 edition 2.0 includes requirements for the construction of transformers. Lithium batteries must comply with IEC 60086-4 for primary cells and IEC 62133 for secondary cells. IEC 60601-1 edition 2.0 also includes humidity testing requirements.
IEC 60601-1-2 defines essential performance parameters for medical equipment with regards to emissions and immunity to electromagnetic interference (EMI) emitted by medical equipment and systems. IEC 60601-1-2 edition 4 introduced significant technical revisions such as risk analysis and management. Now, it includes specifications for immunity test levels according to the environments of intended use, that too dependent on locations that are harmonised with IEC 60601-1-11: hospital and home healthcare facility environment, and special environments.
IEC 17025 includes environmental testing for different climatic conditions and mechanical stress that products are exposed to during their lifetime. This exposes weaknesses in product design or performance that could occur during operation, particularly at extreme levels. It also helps with compliance of products with international regulations, for easier to access global markets.
ISO 14708-3 verifies that electrical and environmental impacts do not affect implantable devices. It includes electrical safety and electromagnetic compatibility (EMC) testing for active implantable medical devices, implants for surgery and implantable neurostimulators.
ISO 14971 checks the compliance of risk management of medical devices. It is meant to identify, quantify and mitigate risks that may be present in all settings of intended use. It foresees misuse and conditions of products or systems. Manufacturers are responsible for planning, performing and documenting the risk management process. They must estimate each applicable risk, probability of occurrence and severity of the risk both before and after risk mitigation measures have been applied. Each aspect of a risk management system should be thoroughly documented to control risk throughout the entire life of a given medical device.
Manufacturers must also ensure that their medical devices are free from bacteria and other substances that could transmit infectious diseases to patients and healthcare workers. This requires development, validation and routine control of sterilisation processes for medical devices and other healthcare products, as described in ISO 11135 for ethylene oxide, in ISO 11137 for gamma radiation and in ISO 17665 for moist heat.
Medical devices are subject to biological evaluation and biocompatibility testing to assess the interaction between a medical device or material that comes in contact with the patient’s body. ISO 10993-1 specific testing is dependent on the type of medical device or material and its intended use. It also depends on the nature and duration of contact between the medical device and the body.
Medical devices must undergo solid electronic testing to carry out testing of microprocessor chips before these are installed on a PCB. Tests for ICs consider their logic gate functions and interconnections between them. After attaching all components to the PCB, testing of mounting and interconnection process needs to be done.
Companies providing testing solutions for medical devices
Rigel Medical offers UniPulse 400, which is an easy-to-use defibrillator analyser with a pacer.
Compliant with IEC 60601-2-2, Uni-Therm electrosurgical analyser by Rigel Medical verifies and calibrates all major electrosurgical generators.
Rigel Medical’s multi-flo infusion pump analyser meets the requirements of IEC 60601-2-24.
Eurofins Met Labs
This company provides a full range of electrical products as per 60601-1 series of standards. EMC and RFID susceptibility to verify compliance with major standards includes 60601, ISO 14708 and other international regulations. It is recognised by OSHA, which indicates compliance to standards required for workplace safety like hospitals, clinics, therapy centres and similar facilities.
It provides implantable device testing for contact lenses, heart pacemakers, ocular implants and stents. Testing systems are configured with BioBath 250 N submersible pneumatic grips for contact lens testing.
Instron 5900 series test systems with Bluehill Universal software and TestProfiler module are used for heart pacemaker testing.
Fluke Biomedical It offers INCU II incubator tester to ensure quality assurance and patient safety by complying with all global standards.
Its IDA-5 infusion pump tester and analyser provides quick preventive maintenance and repair with high accuracy.
The company offers IEC 60601-1-2 compliance EMC testing, EMC edition 3 and EMC edition 4 testing for medical electrostatic discharge (ESD), EMC pre-compliance scans, radiated emissions, radiated immunity, MRI scanners, CT scanners and X-ray equipment, battery safety for medical devices to requirements of IEC 62133, and devices with non-rechargeable lithium batteries to IEC 60086-4.
It provides a wide array of services for electrical and mechanical testing including biocompatibility, electrical safety, current leak, radiated immunity, EMI and ESD, mechanical reliability, environmental exposure, high-altitude, impact, shelf-life, vibration and IEC 60068-2.
It provides pulsatile flow pumps designed to create advanced cardiac or vascular flow loop systems for device testing. Its heart valve pulse duplicator system is designed to assess heart valve prosthesis performance under simulated cardiac conditions.
Whereas, HiCycle determines the durability or fatigue of replacement heart valves and other cardiac devices under physiological loading for R&D and regulatory submissions.
To sum up
Testing of different functional blocks—such as operating system, instruments, hardware and so on—is validated for their intended use. It includes validation of specifications, testing and verification of performance of individual blocks to document results, which can be reviewed later.
While testing medical devices, accuracy within test results is crucial. Only high-quality testing in accordance with relevant standards can assure that products meet the specific requirements and do the job that these are designed for, in an approved and safe way.