Prof. Pecht Presents Keynotes in China and Taiwan

Professor Pecht recently traveled to China and Taiwan to attend several conferences and present keynotes at at the National Chiao Tung University and Nanjing University of Aeronautics and Astronautics.

In China, Prof. Pecht attended the 30th Anniversary of Chinese Journal of Aeronautics. While in Taiwan, Prof. Pecht offered a keynote at the Taiwan ESD and Reliability Conference (TESDC2018) from Nov. 7 – 9 at the National Chiao Tung University in Hsinchu. The extended abstract for his lecture, titled ‘The U.S. and Drug Administration’s Database of Medical Device Adverse Events: A Case Study of ESD Failures,’ can be found below. While at the university, he also visited the Biomedical Electronics Translational Research Center.

Sponsored by Taiwan ESD Association (T-ESDA), the event aims to improve the research and development capabilities of electrostatic discharge (ESD) protection technology and reliability technology. TESDC2018 is a forum for leaders in academia and industry experts to share reliability-related technical examples and research to fuel the practical discussions, advancements, and solutions to improve device safety and quality.

During his time in Taiwan, Prof. Pecht also spoke at Nanjing University of Aeronautics and Astronautics’ International Symposium on Aircraft Airworthiness Technology. His presentation discussed the advances of PHM in the aerospace industry.

The International Symposium on Aircraft Airworthiness Technology serves as an academic exchange platform between global agencies, industries and universities for the sharing of research achievements, improvement of aircraft airworthiness technical abilities, and to promote discussion and exploration of aircraft science and technology.

Abstract: The U.S. and Drug Administration’s Database of Medical Device Adverse Events: A Case Study of ESD Failures

A medical device is defined as any instrument, apparatus or machine, which is intended for use in diagnosis, monitoring, cure or treatment of disease [1]. Medical electrical equipment is a type of medical device which transfers and/or detects energy to or from the patient [2]. Safety and effectiveness are general requirements for medical electrical equipment, as suggested in IEC 60601-1-2 standard.

A medical electrical equipment is considered to be electromagnetically compatible if the device is incapable of interfering or being interfered with by any form of electromagnetic energy in the environment of intended use [3]. One form of electro-magnetic energy, called electrostatic discharge (ESD), involves the rapid transfer of static charge between two materials at different electrical potentials [4]. The most common mechanism of electrostatic charge buildup is through contact and separation of two objects, which is known as triboelectric charging [4]. The discharge, through air or contact, may cause damage to various electronic devices, including integrated circuits.

The Food and Drug Administration (FDA) recognizes the IEC 60601-1-2 [5] as a consensus standard for electromagnetic compatibility of medical electrical equipment, especially as they pertain to safety [6]. This standard provides general immunity requirements against electromagnetic disturbances in the environment of intended use, such as ESD, radiated radiofrequency and electrical transients. The maximum ESD immunity test levels specified in the 4th edition f IEC 60601-1-2 is 8kV levels during contact discharge and 15kV levels during air discharge. In the contact discharge mode, a physical contact is established between the ESD testing simulator and the equipment under test, whereas in the air discharge mode, the discharge occurs through the air. The second (2001) and third (2007) editions of the IEC 60601-1-2 standard required 6kV contact and 8kV air discharge immunity. These requirements in the first edition (1993) were 4kV contact and 8kV air discharge.

Environmental conditions such as ambient relative humidity (RH), are important factors that affect the intensity of an ESD event. It is widely known that ESD is more common in low relative humidity conditions [7] and lowering relative humidity, decreases the surface conductivity, and increases the accumulation of static charges [8]. Previous studies have shown that very high voltages (up to 35kV) can develop at low RH levels, during common everyday actions such as walking on a carpet [4]. If the triboelectric voltages exceed the maximum ESD immunity level of medical electrical equipment, failure of the device due to ESD occurs. Thus, static charge buildup at low RH conditions, pose a significant threat to safe operation of several life-sustaining medical electrical equipment [9], [10], in healthcare facilities and may result in patient injury or death. Maintaining the minimum RH level of a facility above a certain limit, helps to minimize the risk of ESD failures of sensitive electrical devices.

Traditionally, the RH of anesthetizing locations, such as critical care rooms, was maintained above a minimum limit, in order to prevent ignition of flammable anesthetics due to ESD [11]. Nowadays that flammable anesthetics are no longer used, the relevant guidelines provide a minimum RH limit, solely to prevent hypothermia and infection transmission [12]. In fact, current guidelines have completely ignored the impact of the minimum RH on ESD-related failures of electronic devices that are used in anesthetizing locations.

In 2008, the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) published Standard 170, titled ”ventilation of healthcare facilities” that provided RH requirement for anesthetizing locations. Since 2010, there have been changes made to the minimum requirement for relative humidity. Addendum D to the standard, lowered the minimum RH requirement for anesthetizing locations from 30% to 20%. Following this change, some organizations and federal agencies, including Facilities Guidelines Institute (FGI), National Fire Protection Association (NFPA), the Department of Veterans Affairs (VA) and the Centers for Medicare and Medicaid Services (CMS), adopted the new minimum RH requirement proposed by the addendum D to ASHRAE 170 standard.

The ASHRAE 170 Standard Committee made the change particularly based on the result of a review article titled “Literature review of the effect of temperature and humidity on viruses “ by Farhad Memarzadeh [12], the director of technical resources of the National Institute of Health (NIH) and also a member of the ASHRAE 170 Standard Committee (Although the paper was published in 2012, the Committee members had access to the working manuscript in June 2010, when addendum D was approved). The author claimed, after performing an extensive review on the effects of lowering relative humidity on infection transmission and device malfunction due to ESD, “there have been no reported or documented cases of static electricity being an issue in providing safe environments for patients”. Regarding electrostatic discharge issues and equipment malfunction, the article claims that: “Databases from FDA’s Manufacturer and User Facility Device Experience (MAUDE) report (FDA 2011) and Emergency Care Research Institute (ECRI) have been reviewed with no incidence of equipment malfunction or fire due to static discharge”.

This presentation overviews FDA’s device recall and malfunction databases and identifies several documented reports of equipment failure, due to ESD. It is found that the conclusion of the review article and the decisions made by ASHRAE Standard 170 Committee and other organizations and federal agencies that adopted the new RH requirement, were all made based on wrong assumptions regarding the risk of medical equipment malfunction due to ESD. The specifications of the failed devices for their operating RH condition and maximum ESD immunity levels, were also examined, to assess the effects of lowering minimum RH on the performance of the devices that are currently operating in anesthetizing locations. Finally, an estimate of the risk of ESD-related failures after lowering RH is provided. The reader is referred to the paper by Mehdi Kohani and Michael Pecht [13], which provides all the details of this presentation.

References:

[1] “ISO 13485: Medical devices - Quality management systems - Requirements for regulatory purposes.” ISO, 2003.

[2] IEC 60601-1, “Medical electrical equipment – Part 1: General requirements for basic safety and essential performance, Terminology and Definitions.” International Electrotechnical Commission, Genova, 2005.

[3] Food and Drug Administration, “Electromagnetic compatibility aspects of medical device quality systems,” Electromagnetic Compatibility. [Online]. Available: http://www.fda.gov/ICECI/Inspections/InspectionGuides/ucm090595.htm. [Accessed: 03-Jun-2015].

[4] T. Dangelmayer, “Fundamentals of electrostatics,” in ESD Program Management: A Realistic Approach to Continuous Measurable Improvement in Static Control, Springer Science & Business Media, 2012.

[5] IEC 60601-1-2, “Medical electrical equipment — Part 1-2: General requirements for basic safety and essential performance — Collateral standard: Electromagnetic compatibility — Requirements and tests.” International Electrotechnical Commission, Genova, 2014.

[6] U. S. Food and drug administration, Center for Devices and Radiological Health, “Radio Frequency Wireless Technology in Medical Devices - Guidance for Industry and Food and Drug Administration Staff.” [Online]. Available: http://www.fda.gov/RegulatoryInformation/Guidances/ucm077210.htm. [Accessed: 08-Jun-2015].

[7] J. Dai, D. Das, and M. Pecht, “Prognostics-based risk mitigation for telecom equipment under free air cooling conditions,” Appl. Energy, vol. 99, pp. 423–429, Nov. 2012.

[8] J. Paasi, S. Nurmi, R. Vuorinen, S. Strengell, and P. Maijala, “Performance of ESD protective materials at low relative humidity,” J. Electrost., vol. 51–52, pp. 429–434, May 2001.

[9] T.-H. Tan, C.-S. Chang, Y.-F. Huang, Y.-F. Chen, and C. Lee, “Development of a Portable Linux-Based ECG Measurement and Monitoring System,” J. Med. Syst., vol. 35, no. 4, pp. 559–569, Nov. 2009.

[10] J.-W. Lee, K.-H. Lee, Y.-J. Lee, L.-Y. Hong, D.-J. Kim, K.-S. Kim, B. Lee, and M. Lee, “Reusable electrical activity of the heart monitoring patch for mobile/ubiquitous healthcare,” J. Med. Syst., vol. 33, no. 1, pp. 41–46, Feb. 2009.

[11] G. J. Thomas, “Fire and Explosion Hazards with Flammable Anesthetics and Their Control,” J. Natl. Med. Assoc., vol. 52, no. 6, pp. 397–403, Nov. 1960.

[12] F. Memarzadeh, “Literature review of the effect of temperature and humidity on viruses,” ASHRAE Trans., vol. 117, no. 2, 2011.

[13] Mehdi Kohani and Michael Pecht, “New Minimum Relative Humidity Requirements Are Expected to Lead to More Medical Device Failures”, J. Medical Systems, Vol. 40, No. 3, pp. 1–6, Dec. 2015.

Published November 15, 2018