452. More on mobile phones and medical devices
Since the beginning of the nineties there have been warnings not to sue mobile phones in the vicinity of medical devices. Functional failures of dialysis machines, respirators and defibrillators prompted the banning of their use (mobile phones – Editor) in many hospitals in Scandinavia, and then in other countries. Since we believe that a general ban in hospitals is problematic, we decided to investigate the influence of mobile telephone on life-saving
and/or life-support systems, with the aim of establishing rules for its use in hospitals.
A total of 224 devices classified into 23 types of devices were examined. Nine different sets of transmission conditions were applied, giving a total of 2016 tests.
We would therefore recommend that all life-saving and life-support systems that can be used outside the hospital should be made mobile phone proof (this implies testing at the relevant frequencies, with the relevant modulations, at polarisations and levels – probably at 50V/m at least – Editor). When apnoea monitors and respirators are protected from such interference, hazardous situations could be avoided by establishing the rule: “No portables, and mobile phones only at a distance of at least 1 metre from medical devices”. With regard to emergency telephones, the minimum distance to medical devices should be at least 1.5 metres.
(Taken from a translated abstract of “Effect of mobile phone on life-saving and life‑sustaining systems,” Irnich W, Tobisch R, Biomed. Techn. (Berl) 43(6):164-173, 1998.)
453. Evidence of the dangers of mobile phone use in hospitals
- Electrocardiogram traces–interference caused baseline noise (generally not severe enough to be clinically relevant) [5]
- Electrocardiogram traces–interference caused baseline noise (generally not severe enough to be clinically relevant) [5]
- Defibrillators–affected by screen judder; with more powerful phones the units switched off, changed input selection, dumped their stored energy, and displayed asystole incorrectly [4]
- Anaesthetics machines–displayed incorrect oxygen values when mobile phones were used 1 m or less away [4]
- External pacemakers–incorrectly sensed pulses and consequently failed to deliver paced output [4]
- Infusion pumps–prone to alarms and error messages and even reversal in pump direction when phones were less than 1 m away [4]
- Medical monitors–61% had changes to readings, severe judder, buzzing, and system crash when phones were further than 1m away [4]
- Dialysis machines–at 0 m, readings were distorted by phones [4]
- The maximum distance at which any phone caused interference was 2 m; phones closer than 88 cm caused the most severe interference [5]
[4] Medical Devices Agency. Electromagnetic compatibility of medical devices with mobile communications. London: Medical Devices Agency, 1997. (MDA DB 9702.)
[5] Ri JL, Hayes DL, Smith TT, Severson RP. Cellular phone interference with external cardiopulmonary monitoring devices. Mayo Clin Proc 2001;76:11-5.
(Extracted from “Using mobile phones in hospitals: what’s the worst that could happen?” by Layla McCay and Andy Smith, BMJ 2003;326:030352)
The regular “Banana Skins” column was published in the EMC Journal, starting in January 1998. Alan E. Hutley, a prominent member of the electronics community, distinguished publisher of the EMC Journal, founder of the EMCIA EMC Industry Association and the EMCUK Exhibition & Conference, has graciously given his permission for In Compliance to republish this reader-favorite column. The Banana Skin columns were compiled by Keith Armstrong, of Cherry Clough Consultants Ltd, from items he found in various publications, and anecdotes and links sent in by the many fans of the column. All of the EMC Journal columns are available at: https://www.emcstandards.co.uk/emi‑stories, indexed both by application and type of EM disturbance, and new ones have recently begun being added. Keith has also given his permission for these stories to be shared through In Compliance as a service to the worldwide EMC community. We are proud to carry on the tradition of sharing Banana Skins for the purpose of promoting education for EMI/EMC engineers.
