The Coronavirus pandemic has brought the medical electronics industry into sharp focus and resulted in sharp demand for life saving medical equipment all across the world. These include defibrillators, ventilators, pacemakers, intravenous drug-dosing pumps, glucose monitors, ECG machines, BP monitors, anaesthesia machines, ultrasound machines, suction machines, ventricular assist devices, dialysis machines, patient monitoring systems. The devices may be for home use, installed in hospitals, used in diagnostic centres or test laboratories.

We bring to you a series of articles on the severe impact of Electromagnetic Interference (EMI)/Radio Frequency Interference (RFI) on such medical equipment. We also discuss how to mitigate the harmful effects of EMI using appropriate EMI filters and shielding solutions. In this article, we deal with medical ventilators with special emphasis.

A ventilator (also called a respiratory or breathing machine) is a life support equipment that helps people breathe when they can’t breathe on their own. This machine gets oxygen into the lungs and the body and helps to get rid of carbon dioxide through the lungs.

Ventilator machines are usually installed in the ICUs of hospitals in the presence of several other medical equipment in close proximity. There is very high likelihood of all these medical devices emitting EMI noise and affecting the working of the devices nearby. Ventilators especially perform a critical life-saving operation and they need to work in perfect condition 24X7. So it is important to ensure the ventilator device does not emit any EMI to impact nearby devices. At the same time, we need to safeguard the ventilator from ambient EMI emissions.

Medical devices at labs and homes also need to be protected from external EMI that could be generated from a whole host of domestic equipment like mobile phones, Wi-Fi routers, and Bluetooth speakers.

EMI Safety and compliance standards

Efficient handling of EMI/EMC is critical to the Medical industry. Since the impact of EMI related disturbance/damage can cost human lives, the standards of compliance and testing for medical applications are very stringent.

The Food and Drug Administration (FDA) in the US is the governing body that regulates electromagnetic compatibility (EMC) between various devices in the premises – both medical and non-medical. There are different compliance standards in various other countries.

Extensive EMI/EMC Testing, especially onsite testing is carried out to certify the compliance levels to EMI/EMC. The primary standard required by the CDRH/ FDA in the US is IEC 60601-1-2: International Electro-technical Commission – Medical Electrical Equipment – Part 1-2: General Requirements for Safety – Collateral standard: Electromagnetic Compatibility – Requirements and Tests.

Read more about: EMI/EMC Compliance standards and Specifications

 

What are the impacts of EMI/EMC on Medical Equipment?

During the normal functioning of most electrical equipment, some amount of current flows along the earth conductor towards the earth. Known as leakage current, it can cause harm to humans who come in contact with this current. With medical devices such as ventilators placed in physical contact on a patient’s body, this becomes a serious problem.

Product safety standards are very stringent when it comes to limitations on leakage current. For medical equipment, very low leakage current is an important specification that they need to comply with.

Use of EMI or Power Line Filters within Medical Devices becomes an additional source of leakage current. That is because EMI filters may use capacitors against the earth. With the increasing prevalence of EMI filters in medical equipment, tackling leakage current is a serious consideration.

Minimising the Leakage Current from electrical equipment used in healthcare, especially devices which come in direct contact with patients (such as ventilators, lasers, syringe pumps) is of critical importance. Filters used must have adequate clearance and basic insulation for this purpose. Most filter manufacturers specify the maximum expected leakage current so that it is easier to select the most suitable filter.

 

A non-compliant ventilator (with emissions over the prescribed limit) could cause many undesirable outcomes for other medical devices:

• Equipment shutdown – Worst case scenario if the device unexpectedly shuts down when you need it to run 24X7.
• Intermittent failure – Can interrupt normal operation and can be time consuming to troubleshoot. It is quite difficult to trace the source of EMI disturbances, so such failures are tough to rectify. Intermittent failures could cause some features (alarms, lights, motors, display, LED indicators) to fail at critical moments.
• Metastable logic – Caused by a logic gate being stuck between 0 and 1, causing a firmware error which requires a manual restart of the machine.

Immunity threats such as radiated immunity, power disturbances and electrostatic discharge (ESD) need to be taken care of.

 

EMI Shielding solutions

EMI/RFI shielding protects key components in medical devices (like ventilators) from electromagnetic interference and radio frequency interference.

The ISO 13485 standard includes additional requirements for medical device manufacturers to demonstrate their intent to comply with applicable regulatory and statutory shielding requirements.

 

Medical Grade EMI Filters from EMIS INDIA

EMISINDIA is a leading and trusted EMI/EMC solutions provider across several countries the world over. EMIS products and services cater to various industry sectors such as defence, automotive, consumer appliances, power supply and telecommunication sectors.

EMIS specialises in Medical Grade EMI filters and EMI/EMC solutions, with special focus on the needs of the medical industry. These products guarantee high accuracy and comply with the highest international safety standards.

We have a wide range of input filters to reduce conducted and radiated EMI. Our product range also meets requirements concerning EMI susceptibility which support the entire frequency spectrum. We also trade in associated products for adequate grounding, shielding and cabling to manage radiated emissions. Our facility filters comply with the highest international standards of conducted emission tests.

Our Single phase filters series guarantee to limit the leakage currents below 0.5 mA in order to meet the requirements of the medical standards IEC/EN 60601 for equipment with patient contact or other medical environments.

Generally as part of EMI filter design, capacitors from all conductors are wired to ground. However EMIS Medical grade filters are designed in such a way that there are no capacitors connected between lines to ground. Therefore EMIS filters emit very minimum leakage current.

EMIS Medical Grade Filters comes in a wide range which gives the customer many options to choose in terms of Leakage current and different circuit configuration to fulfil the EMC requirements as per relevant CISPR standards. The product series is available in different mounting styles.

Medical Grade Filters from EMIS are tested and approved as per the Standards UL 60939-3.

The applications for EMIS medical grade filters include various medical devices such as Patient Monitoring Systems, Diagnostic Equipment and scanners. These high accuracy filters with stringent safety and compliance standards are also used in various IT Systems and other electronics systems.

 

Product Features (Medical Grade EMI Filters):

• Very low Leakage Current
• Fully compliant to the requirements of the standard IEC 60601
• Available in different mounting style and termination
• Available in different circuit configuration
• Supports up-to 125A
• All product series have UR approval as per UL 60939-3 Standard

 

EMIS INDIA Medical Grade Filters Product Series

The Medical Grade filters, especially suitable for ventilators, X-Ray machines and other diagnostic equipment are listed below:

Our series range of IEC Inlet type filters are designed to suppress undesirable electrical disturbances in Power Lines. They limit the amplitude of interfering voltages on AC power lines and prevent them from propagating into or out of the filtered equipment.

Our series range of Single and dual stage high performance filters are also suitable for low leakage requirements such as in the medical industry. They give superior performance with low impedance loads controlling pulsed, continuous and intermittent interference noise and where high levels of mains borne interference is present.

Depending on the installation site and application, several components are available for EMI protection. EMIS has a wide range of high end filters for applications up to 15 GHz frequency range for medical applications. These filters are available up to 2500 Amps rated current.

 

To further explore our product offerings for the healthcare domain, visit our webpage https://emisglobal.com/markets/industries/medical-and-healthcare/

 

EMI Solutions Pvt Ltd is an ISO 9001-2015 and 14001-2015 certified company that exclusively caters to EMI related requirements. We deliver both standard manufactured and custom designed EMI filters and components. We are one of the largest EMI/RFI Filter manufacturers in India. In addition, our state-of-the art EMI/EMC test facility and technical consultancy services give our customers the convenience of TOTAL SOLUTIONS TO EMI under one roof.