Bonjour everyone;
I recently published an article in the CANNT journal on the use of portable phones in hemodilaysis units. A very good friend suggested that I post the article here to invite more Canadian technologists to write for the different journals and as well as this website.
I hope you will find it interesting and let's get writing !
Cheers,
Gil
This article Portable phones in hemodialysis units: Are we interfering? by Gil Grenier was first published in the CANNT Journal 2005 Volume 15 Number 2 pages 48-49. Copyright 2005 Canadian Association of Nephrology Nurses and Technologists (CANNT ). Reprinted with permission.
Portable phones in the hemodialysis units:
Are we interfering ?
Abstract
Are portable and/or cell phones too risky to use in the hemodialysis units ? How can electromagnetic interference affect the equipment ? Is there a real concern for the health care workers and the patients ? This article offers answers to the above questions as well as reviews the different recommendations and guidelines from the Canadian Standards Association (CSA) and the U.S. Food and Drug Administration (FDA) in order to formalize recommendations and help us make a decision.
Key words: portable telephones; electromagnetic interference; hemodialysis equipment
Introduction
On a cold winter night, my wife and I drove to the National Arts Centre for a classic holiday treat, The Nutcracker highlighted by Tchaikovskys memorable music. After finding our way to the theatre, we sat down in our seats with excitement. While everybody else was busy getting comfortable as well, the Matre de Crmonie walked in front of the gigantic red curtain requesting our attention as we were reminded to turn our Star Trek equipment off. Immediately following this short introduction, the lights started to dim in the theatre. I rapidly looked at my wife with panic since I was still trying to turn my equipment off without much success.
This may sound funny at first, but how many times have we been disturbed by this new technology used by all the Captain Kirks of this world including ourselves ? The new generations need to communicate more, and they need to communicate everywhere. This is reality. We all understand how this new technology affects our daily life. Lets discuss the impact, if any, on our hemodialysis equipment used in centre or in a home setting.
Electromagnetic Interference
Portable phones are basically two-way radios that communicate with land-based radios, or cell sites. These are connected to phone networks. There are mainly two (2) types of portable phones, analog and digital. Analog phones have been around for many years and are ready for retirement. Digital phones are relatively new. Digital service providers can offer additional features on digital phones such as caller ID, display window and extended battery life, features that make this newer technology much more attractive to the general public.
The real concern with portable phones in the medical field is the possible radio frequency interference, often called electromagnetic interference (EMI). What is this ? It is simply any electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronics/electrical equipment (Wikipdia LEncyclopdie Libre, fr.wikipedia.org). Generally, electromagnetic interference is very difficult to avoid and most Research and Development (R&D) engineers regularly adapt their equipment through design and operational changes as the wireless revolution is well underway in our society.
There are two (2) different possible sources of interference, intentional and unintentional.
Intentional: signals from TV transmitters, remote controls, wireless phones, cellular phones, taxi radios and microwave ovens are examples of intentional interference.
Unintentional: defective fluorescent lights and lightning are good examples of possible sources of interference.
Electromagnetic signals can travel through space in two different ways, in the air from one location to the next (transmitter to antenna or receiver) or through hardware cables and wires (coaxial TV cable for example). The intensity of electromagnetic signals is measured in volt/meter (V/m). The closer to the antenna, the stronger the signal is.
The other aspect of electromagnetic signals that must be considered is the frequency. The frequency is measured in Hertz (Hz). The low frequency signals do not react in the same manner as the high frequency signals. Higher frequency signals and light signals travel in a very similar way, where as low frequency signals tend to travel at the surface of the earth and even below the surface to some degree.
The problem
All mobile phones emit radiofrequency waves in standby mode as well as when in use (Klein and Djaiani 2002). As electromagnetic signals can travel through space or through wires and cables, it is then easy to accept that a signal from a cellular phone travelling through the air looking for a receiver antenna can be accidentally picked-up by wires found in any other piece of electronic equipment and therefore be the source of interference. Such interference can possibly create false alarms or even the equipment to lock and therefore requiring a reboot sequence. A recent study (Morrissey et al. 2002) conducted in cooperation with Canadian and American hospitals confirmed that the majority of dialysis machines were not critically affected by cellular phones. However, on one model it was noted that the blood pump slowed down even though the speed indication remained constant when exposed to cell phone signals at 0.5 m from the back. The closer the phone is to the medical equipment, the greater the chances of creating interference. Other observations noted with different models of hemodialysis machines in this study were variations (increase or decrease) of the arterial and/or venous pressure readings as well as the triggering of the air bubble alarm system.
In 2004, different suppliers have published the information through bulletins and letters to users. It is not the purpose of this manuscript to review these recommendations in details as they can be obtained directly from the suppliers. Manufacturers that were contacted have confirmed their equipment meet the requirements regarding electromagnetic compatibility. They have performed extensive testing and found that their equipment is most likely not affected by digital cell phones if at all. One manufacturer confirmed that analog cell phones should be avoided as they can affect the operation of the equipment by creating false pressures alarms when held close to the monitor. Some manufacturers are willing to provide very specific information as far as frequencies of operation and radiation levels (V/m) of portable phones used for their performance tests. General manufacturer recommendations are to only use cellular phones when not within 0.5 meters from the dialysis delivery systems and to use them conditionally. In a systematic review published last August (Lawrentschuk and Bolton 2004) it was concluded that all studies recommended some type of restriction of mobile phone use in hospitals, with use greater than 1 m from equipment and restrictions in clinical areas being the most common. The manufacturer of your equipment may recommend not to use cellular phones in areas where patient care is carried out.
The Canadian Standards Associations recommendation is to use cellular phones in a location where medical equipment is not in patient use such as waiting area, hallway or lounge (Electrical Safety and Essential Electrical Systems in Health Care Facilities standards CAN/CSA-Z32-99).
The U.S. Food and Drug Administration (FDA) maintains an informational web site where we can find reference articles, documents related to safety alerts and very specific recommendations. It is recognized that radiofrequency energy (RF) from wireless phones can interact with some electronic devices (fda.gov/cdrh/emc/index.html). Standards are continually being developed and updated to help manufacturers in the design of their medical equipment.
Conclusion
Although it would be very desirable for patients, visitors or staff to use cellular phone near dialysis delivery systems, one should proceed with caution. The newer technology dialysis delivery systems are more resistant to electromagnetic interference but still not 100 % (EMI) proof as indicated by Morrissey, Swicord and Balzano (2002) in their study.
Recommendations
The very first step in ensuring a safe environment for the patients should be to discontinue using portable phones immediately should any interference be noted. Analog type cellular phone should definitely be avoided. If not already done so, providing specific information regarding the model in use (brand name, model number and frequency) to your equipment supplier in order to obtain specific performance test data, should be seriously considered. Last but not least, ensuring adequate grounding and proper shielding on preventive maintenance will contribute positively toward ensuring the safety of the equipment.
In the Nephrology Program of The Ottawa Hospital, cellular phones are not allowed in the treatment areas. Wireless phones (non cellular) are provided for the patients while receiving the hemodialysis treatments. We have not noticed any interference or disturbance since their introduction two (2) years ago at the Riverside Campus, a thirty (30) stations unit.
As the number of Canadian studies and/or published papers is still somewhat limited, it would be very valuable for the Canadian dialysis community to received feedback from the different units. We invite nephrology nurses and technologists from across Canada to submit letters to the CANNT Journal outlining how you are managing this problem in your dialysis facility.
Remember, if you can not use your portable phone near your equipment, you can always pick up the messages in Captain Kirks mailbox later !
Please contact me directly with letters for the CANNT Journal on this topic:
Gil Grenier e-mail: gigrenier@ottawahospital.on.ca
References
Canadian Standards Association. (2003, Jan.). Electrical Safety and Essential Electrical Systems in Health Care Facilities. CAN/CSA-Z32-99
Klein, A.A. & Djaiani, G.N. (2003). Mobile phones in the hospital past, present and future. Anaesthesia 58: 353357
Lawrentschuk, N. & Bolton, D.M. (2004). Mobile phone interference with medical equipment and its clinical revelance: a systematic review. Medical Journal of Australia (MJA), 181 (3), 145-149.
Morrissey, J.J., Swicord, M. & Balzano, Q. (2002). Characterization of electromagnetic interference of medical devices in the hospital due to cell phones. Health Physics, Volume 82 (1), 45-51
U.S. Food and Drug Administration. (2003). Interference with medical devices. Retrieved April 24, 2005, from www.fda.gov/cdrh/emc/index.html
Wikipdia LEncyclopdie Libre fr.wikipedia.org
I recently published an article in the CANNT journal on the use of portable phones in hemodilaysis units. A very good friend suggested that I post the article here to invite more Canadian technologists to write for the different journals and as well as this website.
I hope you will find it interesting and let's get writing !
Cheers,
Gil
This article Portable phones in hemodialysis units: Are we interfering? by Gil Grenier was first published in the CANNT Journal 2005 Volume 15 Number 2 pages 48-49. Copyright 2005 Canadian Association of Nephrology Nurses and Technologists (CANNT ). Reprinted with permission.
Portable phones in the hemodialysis units:
Are we interfering ?
Abstract
Are portable and/or cell phones too risky to use in the hemodialysis units ? How can electromagnetic interference affect the equipment ? Is there a real concern for the health care workers and the patients ? This article offers answers to the above questions as well as reviews the different recommendations and guidelines from the Canadian Standards Association (CSA) and the U.S. Food and Drug Administration (FDA) in order to formalize recommendations and help us make a decision.
Key words: portable telephones; electromagnetic interference; hemodialysis equipment
Introduction
On a cold winter night, my wife and I drove to the National Arts Centre for a classic holiday treat, The Nutcracker highlighted by Tchaikovskys memorable music. After finding our way to the theatre, we sat down in our seats with excitement. While everybody else was busy getting comfortable as well, the Matre de Crmonie walked in front of the gigantic red curtain requesting our attention as we were reminded to turn our Star Trek equipment off. Immediately following this short introduction, the lights started to dim in the theatre. I rapidly looked at my wife with panic since I was still trying to turn my equipment off without much success.
This may sound funny at first, but how many times have we been disturbed by this new technology used by all the Captain Kirks of this world including ourselves ? The new generations need to communicate more, and they need to communicate everywhere. This is reality. We all understand how this new technology affects our daily life. Lets discuss the impact, if any, on our hemodialysis equipment used in centre or in a home setting.
Electromagnetic Interference
Portable phones are basically two-way radios that communicate with land-based radios, or cell sites. These are connected to phone networks. There are mainly two (2) types of portable phones, analog and digital. Analog phones have been around for many years and are ready for retirement. Digital phones are relatively new. Digital service providers can offer additional features on digital phones such as caller ID, display window and extended battery life, features that make this newer technology much more attractive to the general public.
The real concern with portable phones in the medical field is the possible radio frequency interference, often called electromagnetic interference (EMI). What is this ? It is simply any electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronics/electrical equipment (Wikipdia LEncyclopdie Libre, fr.wikipedia.org). Generally, electromagnetic interference is very difficult to avoid and most Research and Development (R&D) engineers regularly adapt their equipment through design and operational changes as the wireless revolution is well underway in our society.
There are two (2) different possible sources of interference, intentional and unintentional.
Intentional: signals from TV transmitters, remote controls, wireless phones, cellular phones, taxi radios and microwave ovens are examples of intentional interference.
Unintentional: defective fluorescent lights and lightning are good examples of possible sources of interference.
Electromagnetic signals can travel through space in two different ways, in the air from one location to the next (transmitter to antenna or receiver) or through hardware cables and wires (coaxial TV cable for example). The intensity of electromagnetic signals is measured in volt/meter (V/m). The closer to the antenna, the stronger the signal is.
The other aspect of electromagnetic signals that must be considered is the frequency. The frequency is measured in Hertz (Hz). The low frequency signals do not react in the same manner as the high frequency signals. Higher frequency signals and light signals travel in a very similar way, where as low frequency signals tend to travel at the surface of the earth and even below the surface to some degree.
The problem
All mobile phones emit radiofrequency waves in standby mode as well as when in use (Klein and Djaiani 2002). As electromagnetic signals can travel through space or through wires and cables, it is then easy to accept that a signal from a cellular phone travelling through the air looking for a receiver antenna can be accidentally picked-up by wires found in any other piece of electronic equipment and therefore be the source of interference. Such interference can possibly create false alarms or even the equipment to lock and therefore requiring a reboot sequence. A recent study (Morrissey et al. 2002) conducted in cooperation with Canadian and American hospitals confirmed that the majority of dialysis machines were not critically affected by cellular phones. However, on one model it was noted that the blood pump slowed down even though the speed indication remained constant when exposed to cell phone signals at 0.5 m from the back. The closer the phone is to the medical equipment, the greater the chances of creating interference. Other observations noted with different models of hemodialysis machines in this study were variations (increase or decrease) of the arterial and/or venous pressure readings as well as the triggering of the air bubble alarm system.
In 2004, different suppliers have published the information through bulletins and letters to users. It is not the purpose of this manuscript to review these recommendations in details as they can be obtained directly from the suppliers. Manufacturers that were contacted have confirmed their equipment meet the requirements regarding electromagnetic compatibility. They have performed extensive testing and found that their equipment is most likely not affected by digital cell phones if at all. One manufacturer confirmed that analog cell phones should be avoided as they can affect the operation of the equipment by creating false pressures alarms when held close to the monitor. Some manufacturers are willing to provide very specific information as far as frequencies of operation and radiation levels (V/m) of portable phones used for their performance tests. General manufacturer recommendations are to only use cellular phones when not within 0.5 meters from the dialysis delivery systems and to use them conditionally. In a systematic review published last August (Lawrentschuk and Bolton 2004) it was concluded that all studies recommended some type of restriction of mobile phone use in hospitals, with use greater than 1 m from equipment and restrictions in clinical areas being the most common. The manufacturer of your equipment may recommend not to use cellular phones in areas where patient care is carried out.
The Canadian Standards Associations recommendation is to use cellular phones in a location where medical equipment is not in patient use such as waiting area, hallway or lounge (Electrical Safety and Essential Electrical Systems in Health Care Facilities standards CAN/CSA-Z32-99).
The U.S. Food and Drug Administration (FDA) maintains an informational web site where we can find reference articles, documents related to safety alerts and very specific recommendations. It is recognized that radiofrequency energy (RF) from wireless phones can interact with some electronic devices (fda.gov/cdrh/emc/index.html). Standards are continually being developed and updated to help manufacturers in the design of their medical equipment.
Conclusion
Although it would be very desirable for patients, visitors or staff to use cellular phone near dialysis delivery systems, one should proceed with caution. The newer technology dialysis delivery systems are more resistant to electromagnetic interference but still not 100 % (EMI) proof as indicated by Morrissey, Swicord and Balzano (2002) in their study.
Recommendations
The very first step in ensuring a safe environment for the patients should be to discontinue using portable phones immediately should any interference be noted. Analog type cellular phone should definitely be avoided. If not already done so, providing specific information regarding the model in use (brand name, model number and frequency) to your equipment supplier in order to obtain specific performance test data, should be seriously considered. Last but not least, ensuring adequate grounding and proper shielding on preventive maintenance will contribute positively toward ensuring the safety of the equipment.
In the Nephrology Program of The Ottawa Hospital, cellular phones are not allowed in the treatment areas. Wireless phones (non cellular) are provided for the patients while receiving the hemodialysis treatments. We have not noticed any interference or disturbance since their introduction two (2) years ago at the Riverside Campus, a thirty (30) stations unit.
As the number of Canadian studies and/or published papers is still somewhat limited, it would be very valuable for the Canadian dialysis community to received feedback from the different units. We invite nephrology nurses and technologists from across Canada to submit letters to the CANNT Journal outlining how you are managing this problem in your dialysis facility.
Remember, if you can not use your portable phone near your equipment, you can always pick up the messages in Captain Kirks mailbox later !
Please contact me directly with letters for the CANNT Journal on this topic:
Gil Grenier e-mail: gigrenier@ottawahospital.on.ca
References
Canadian Standards Association. (2003, Jan.). Electrical Safety and Essential Electrical Systems in Health Care Facilities. CAN/CSA-Z32-99
Klein, A.A. & Djaiani, G.N. (2003). Mobile phones in the hospital past, present and future. Anaesthesia 58: 353357
Lawrentschuk, N. & Bolton, D.M. (2004). Mobile phone interference with medical equipment and its clinical revelance: a systematic review. Medical Journal of Australia (MJA), 181 (3), 145-149.
Morrissey, J.J., Swicord, M. & Balzano, Q. (2002). Characterization of electromagnetic interference of medical devices in the hospital due to cell phones. Health Physics, Volume 82 (1), 45-51
U.S. Food and Drug Administration. (2003). Interference with medical devices. Retrieved April 24, 2005, from www.fda.gov/cdrh/emc/index.html
Wikipdia LEncyclopdie Libre fr.wikipedia.org
