G Model RESUS-5874; No. of Pages 2
ARTICLE IN PRESS Resuscitation xxx (2014) xxx.e1–xxx.e2
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Letter to the Editor Defibrillators can be susceptible to electromagnetic fields from adjacent portable suction units Sir, It has been known for some time that Philips HeartStart MRx defibrillators can fail without warning during battery power operation if it is subject to significant electromagnetic interference (EMI). In such circumstances, the charge capacity of the onboard smart battery can be reduced to an inoperable level.1 The failure mechanism was not fully described by the manufacturers in their advisory letter. The exact level of EMI which can cause the malfunction was also not disclosed. Medical professionals or the equipment users have the responsibility for avoiding exposing their equipment to high levels of EMI, in order to prevent equipment malfunction.2 An investigation was initiated to determine if any Philips MRx defibrillators on resuscitation trolleys at the Royal United Hospital (RUH) Bath were exposed to excessive EMI.
The survey results proved that all the trolley locations within the RUH maintained a low level of EMI, with acceptably low radio frequency (RF) and magnetic interferences. However, it was found that the Laerdal LSU 4000 portable suction unit present on many trolleys emits a high level of EMI, with field strengths up to 180 V/m. This is approximately 90 times that are emitted by a typical modern mobile telephone. Emergency medical devices such as defibrillators are only required to be immune to 10 V/m interference levels.2 The field strength will drop to an acceptable level at 1 m away from the unit. There are 35 suction units of the same model deployed onsite and an identical emission pattern was found on all units. Hence, within 1 m distance from this suction unit, any electrical medical equipment can be susceptible to EMI which can lead to malfunction or in the worst case, irreversible damage.2 Portable suction units are commonly located adjacent to defibrillators, and they are often used at the same time during resuscitation. As the Philips MRx defibrillator battery can be affected by high levels of EMI, although the exact level is
Fig. 1. The location where the highest measurements were registered; and the preferred position when Laerdal LSU 4000 portable suction unit is placed adjacent to Philips MRx Defibrillator on resuscitation trolley. 0300-9572/$ – see front matter © 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.resuscitation.2014.01.026
Please cite this article in press as: Lee SM, et al. Defibrillators can be susceptible to electromagnetic fields from adjacent portable suction units. Resuscitation (2014), http://dx.doi.org/10.1016/j.resuscitation.2014.01.026
G Model RESUS-5874; No. of Pages 2 xxx.e2
ARTICLE IN PRESS Letter to the Editor / Resuscitation xxx (2014) xxx.e1–xxx.e2
unknown, users should avoid subjecting the defibrillator to such conditions. The high emissions were measured on the top front right hand corner of the suction unit where a power rectifying circuit is located (Fig. 1). An immediate remedial action can be made to ensure that any medical equipment is relocated to the left hand side of the portable suction unit on the trolleys (Fig. 1). In addition, all medical equipments should also be placed 1 m away from the LSU 4000 suction unit to avoid the exposure of high level EMI. At the RUH, 55% of Philips MRx defibrillators are on trolleys equipped with LSU 4000 portable suction units. It was found that 54% of them required the defibrillator to be relocated to the left of the portable suction unit. The manufacturer and the Medicines and Healthcare products Regulatory Agency, UK, have been notified about these findings. A long-term remedial action may be implemented in the future by the manufacturer. In the meantime, it is strongly recommended that the positions of the Philips Defibrillator and LSU suction unit be checked, and the devices are relocated if necessary.
Conflicts of interest statement The authors have no conflicts of interest to declare. References 1. Customer Information Letter CIL86100122A. Philips Healthcare; 2013. 2. BS EN 6060601-1-2:2007, Medical electrical Equipment, Part 1–2: general requirements for safety – collateral standard: electromagnetic compatibility – requirements and tests.
S.M. Lee ∗ D. Hyde A. Dimunge L.J. Grant Department of Medical Physics & Bioengineering, Royal United Hospital Bath, UK ∗ Corresponding author. E-mail address: [email protected] (S.M. Lee)
Available online xxx
Please cite this article in press as: Lee SM, et al. Defibrillators can be susceptible to electromagnetic fields from adjacent portable suction units. Resuscitation (2014), http://dx.doi.org/10.1016/j.resuscitation.2014.01.026
ARTICLE IN PRESS Resuscitation xxx (2014) xxx.e1–xxx.e2
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Letter to the Editor Defibrillators can be susceptible to electromagnetic fields from adjacent portable suction units Sir, It has been known for some time that Philips HeartStart MRx defibrillators can fail without warning during battery power operation if it is subject to significant electromagnetic interference (EMI). In such circumstances, the charge capacity of the onboard smart battery can be reduced to an inoperable level.1 The failure mechanism was not fully described by the manufacturers in their advisory letter. The exact level of EMI which can cause the malfunction was also not disclosed. Medical professionals or the equipment users have the responsibility for avoiding exposing their equipment to high levels of EMI, in order to prevent equipment malfunction.2 An investigation was initiated to determine if any Philips MRx defibrillators on resuscitation trolleys at the Royal United Hospital (RUH) Bath were exposed to excessive EMI.
The survey results proved that all the trolley locations within the RUH maintained a low level of EMI, with acceptably low radio frequency (RF) and magnetic interferences. However, it was found that the Laerdal LSU 4000 portable suction unit present on many trolleys emits a high level of EMI, with field strengths up to 180 V/m. This is approximately 90 times that are emitted by a typical modern mobile telephone. Emergency medical devices such as defibrillators are only required to be immune to 10 V/m interference levels.2 The field strength will drop to an acceptable level at 1 m away from the unit. There are 35 suction units of the same model deployed onsite and an identical emission pattern was found on all units. Hence, within 1 m distance from this suction unit, any electrical medical equipment can be susceptible to EMI which can lead to malfunction or in the worst case, irreversible damage.2 Portable suction units are commonly located adjacent to defibrillators, and they are often used at the same time during resuscitation. As the Philips MRx defibrillator battery can be affected by high levels of EMI, although the exact level is
Fig. 1. The location where the highest measurements were registered; and the preferred position when Laerdal LSU 4000 portable suction unit is placed adjacent to Philips MRx Defibrillator on resuscitation trolley. 0300-9572/$ – see front matter © 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.resuscitation.2014.01.026
Please cite this article in press as: Lee SM, et al. Defibrillators can be susceptible to electromagnetic fields from adjacent portable suction units. Resuscitation (2014), http://dx.doi.org/10.1016/j.resuscitation.2014.01.026
G Model RESUS-5874; No. of Pages 2 xxx.e2
ARTICLE IN PRESS Letter to the Editor / Resuscitation xxx (2014) xxx.e1–xxx.e2
unknown, users should avoid subjecting the defibrillator to such conditions. The high emissions were measured on the top front right hand corner of the suction unit where a power rectifying circuit is located (Fig. 1). An immediate remedial action can be made to ensure that any medical equipment is relocated to the left hand side of the portable suction unit on the trolleys (Fig. 1). In addition, all medical equipments should also be placed 1 m away from the LSU 4000 suction unit to avoid the exposure of high level EMI. At the RUH, 55% of Philips MRx defibrillators are on trolleys equipped with LSU 4000 portable suction units. It was found that 54% of them required the defibrillator to be relocated to the left of the portable suction unit. The manufacturer and the Medicines and Healthcare products Regulatory Agency, UK, have been notified about these findings. A long-term remedial action may be implemented in the future by the manufacturer. In the meantime, it is strongly recommended that the positions of the Philips Defibrillator and LSU suction unit be checked, and the devices are relocated if necessary.
Conflicts of interest statement The authors have no conflicts of interest to declare. References 1. Customer Information Letter CIL86100122A. Philips Healthcare; 2013. 2. BS EN 6060601-1-2:2007, Medical electrical Equipment, Part 1–2: general requirements for safety – collateral standard: electromagnetic compatibility – requirements and tests.
S.M. Lee ∗ D. Hyde A. Dimunge L.J. Grant Department of Medical Physics & Bioengineering, Royal United Hospital Bath, UK ∗ Corresponding author. E-mail address: [email protected] (S.M. Lee)
Available online xxx
Please cite this article in press as: Lee SM, et al. Defibrillators can be susceptible to electromagnetic fields from adjacent portable suction units. Resuscitation (2014), http://dx.doi.org/10.1016/j.resuscitation.2014.01.026
