Safety of electrical medical equipment
All types of electrical medical equipment can present a range of hazards to the user, the patient and to service personnel
Most design engineers recognise that conformance and verification of medical devices to BS EN IEC 60601-1 will meet the safety standards required for such an item. Here, Steve Hughes, managing director of medical power specialist REO UK, explores the EN 60601-1 standard and how it helps keep both patients and caregivers safe.
EN 60101-1 is part one in a group of standards that encompasses the essential performance, electromagnetic compatibility and safety of medical equipment and systems that have an applied part of transferring energy in a patient’s care or detecting that energy. This includes a wide range of devices including patient monitors, infant incubators and cardiac defibrillators.
While EN 60101-1 is the basic general standard of devices that will always apply if the device falls under the general scope, it is up to design engineers to understand which collateral and particular standards apply.
EN 60601-1-x is the collateral standard — the primary standard that has several specific standards directly related to the safety of medical equipment. For example, 60601-1-3 relates to the collateral standard of radiation protection in diagnostic X-ray equipment, ensuring that the irradiation of the patient, operator and staff can be kept as low as reasonably achievable, without jeopardising the benefit of the radiological procedure.
There is also the new EN 60601-1-2 collateral standard, described as the basic safety and essential performance of medical equipment and systems in the presence of electromagnetic disturbances and electromagnetic disturbances emitted by that equipment and systems. This standard addresses a concern affecting both the medical device in question and other devices in the vicinity. The reason for introducing this new standard is due to the growing use of devices that connect wirelessly using a cellular network, like smartphones or laptops.
EN 60101-2-x is the set of standards specific to different types of medical equipment, providing additional information to the collateral standards. EN 60601-2-8, for example, encompasses the particular requirements for the basic safety and essential performance of therapeutic X-ray equipment operating in the range of 10kV to MV.
When these standards are not followed, the use of mains-powered diagnostic, measurement and treatment equipment — as well as the presence of electrically-conductive bodily fluids, gels, and other solutions used in a patient’s care — potentially exposes the patient or caregiver to the risk of injury directly due to leakage current resulting from improper grounding and electrical isolation.
This means that virtually every piece of equipment destined for use in a medical environment needs isolation from the mains. Most medical equipment is manufactured and tested to incorporate an isolation transformer — dependant on the class of the equipment (Class 1 or 2) — offering improved safety, noise reduction and better power quality. To ensure this for more medical manufacturers, REO has focussed attention on developing a range of isolation transformers that are specially designed to meet the exacting requirements of the medical sector.
REOMED II is the latest generation of medical isolation transformers to allow most Class 1 equipment to pass the ‘electrical’ side of the medical standard EN 60601-1, using polyurethane coated toroidal cores, which are more efficient and less likely to radiate an electromagnetic field than other designs.
Electrical safety testing of electronic devices remains a crucial part of the overall validation of medical equipment. The EN 60601-1 standard is complex — the related collateral and particular standard often present additional requirements and considerations for medical design engineers, but partnering with a supplier that offers compliant components is the first step in the way to assurance that the product is reliable and safe.