Gary R. Olhoeft, PhD Professor of Geophysics Colorado...
Transcript of Gary R. Olhoeft, PhD Professor of Geophysics Colorado...
Electromagnetic Interference with Medical Implants
Gary R. Olhoeft, PhD
Professor of Geophysics
Colorado School of Mines
8 November 2009
Professor of Geophysics
I make very sensitive electrical, magnetic and electromagnetic measurements to study the roots of earthquakes and volcanoes,
What are EMI and RFI?
• Interference is any unwanted effect such as music playing too loud for you to hear a phone conversation (signal to music listener but noise to phone user)
• EMI: Electromagnetic interference is electric or magnetic fields producing an unwanted effect (typically at low frequency by induction)
• RFI: Radiofrequency interference is electro-magnetic fields producing an unwanted effect (typically at high frequency by radiation)
EMI/RFI Interfere with Geophysics
• Cell phones, radio, TV and power lines are all sources of signal to users and of noise and interference to geophysics
• Natural fields from the earth and sun are both sources of noise and interference,and also signal
• What is a desirable signal and what is an unwanted noise depends on the problemand perspective (like the music and phone)
Medical Implants
• Cardiac pacemakers/defibrillators• Neurostimulators (Deep Brain Stimulators)
for Parkinson’s DiseaseObsessive Compulsive DisorderDepression
• Infusion pumps (diabetes)• Artificial Hearts• Metal rods to support broken bones• Spinal stimulators• Hearing aids
Medical Implants
One definition of implants is as having a minimum lifespan of 3 months, as penetrating living tissue, as having a physiologic interaction, and as being retrievable.
There is no tracking for medical implant devices (MIDs), but NIH says they have been used widely for more than 40 years, and it is estimated that 8 percent to 10 percent of Americans (20-25 million people) currently have such a device.
Interference with Medical Implants
• Interference can:
– Prevent normal therapeutic function
– Reset or reprogram the device
– Bring damaging energy into the device or body
– Cause injury including death
EMI/RFI
• Any metal object can act as antenna
• If the metal is not the right size, shape and orientation, it will not be very efficient, but still an antenna
• A metal tooth filling can be a radio receiver
Medtronics Kinetra DBS Patient Manual
• Lists more than 16 pages of EMI warnings:
– Cardiac Defibrillators (1 kV), Diathermy and MRI
– Theft detectors and security gates(airports, schools, courts, libraries and retail stores)
– CB or ham radios, TV & radio transmitting towers
– Electric arc welding equipment
– Induction heaters and Industrial blast furnaces
– Power lines, electric substations and generators
– Cell phones
DBS and Diathermy EMI
• Shortwave, Microwave, or Ultrasonic Diathermy (deep heat treatment)
• “Energy from diathermy can be transferred through your implanted system, can cause tissue damage and can result in severe injury or death.” – Medtronics Kinetra neurostimulator patient manual
DBS and MRI RFI
• “Performing MRI with this equipment can cause tissue lesions … resulting in serious and permanent injury including coma, paralysis, or death.” – Medtronics Kinetra patient manual
Security Gates
• Walk through metal detectors up to 374,100 nT at 100-3,500 Hz (FDA)
• DBS programmer 80,000 nT at 130-185 Hz
• Airports, museums, courts,hospitals, schools, more…
FDA Aware of Problem
Electro-Magnetic Interference from Security Systems
“In the late 1990s, CDRH identified over 100 reports of injuries to patients with critical active implanted medical devices such as pacemakers/defibrillators and nerve stimulators. Injuries often occurred when patients walked through some electromagnetic security devices like metal detectors.”
Retail & Library Theft Detection
• Electronic Article Surveillance (EAS) Systems
• Up to 220,000 nT at 219 Hz (FDA)
• DBS programmer 80,000 nT at 130-185 Hz
• FDA has found 28 cardiac pacemakers, automatic implantable cardiac defibrillators (AICD), spinal stimulators, hearing aids and ambulatory infusion pumps have failed or malfunctioned in the presence of EAS systems
DBS Interference
• Not cited by Medtronics:
-Wireless Inductive Chargers
-Roadside Microwave Traffic Sensors
-Electric Car Chargers
-TASER (Neuro-musculature Incapacitation)
-Active Denial System (Nonlethal Beam Weapon) (CSI:NY 28 Oct 2009)
-Lightning
Active Denial Systemaka “Silent Guardian”
Developed by DoD for “nonlethal” crowd control
On CSI:NY 28 Oct 2009 episodekilled a man with a cardiac pacemaker
In demand for ship antipiracyand by law enforcementpersonnel
Lightning
• Huge transient currents and magnetic fields
• NWS says only flash floods kill more people than lightning
• Literature reports lightning has reset DBS
FDA
“FDA's Center for Devices and Radiological Health (CDRH) is responsible for regulating firms who manufacture, repackage, relabel, and/or import medical devices sold in the United States. In addition, CDRH regulates radiation-emitting electronic products (medical and non-medical) such as lasers, x-ray systems, ultrasound equipment, microwave ovens and color televisions.” - FDA
FDA CDRH
“FDA regulates radiation emitting electronic products. The purpose is to prevent unnecessary exposure to radiation due to the use of these products. There are specific requirements that apply to all radiation emitting electronic products in order to comply with the provisions of the Food, Drug and Cosmetic Act. If the product is also a medical device, the product must also comply with the medical device regulations.”
FDA CDRH
The term "electronic product radiation" means any ionizing or non-ionizing electromagneticor particulate radiation, or any sonic, infrasonic, or ultrasonic wave…
FDA Aware of Problem
• 1996 FDA Science Forum Poster Abstract: A-46 From the 1996 FDA Science Forum. Abstract # A-46. Survey of Several Electronic Article Surveillance Systems for the Potential for Electromagnetic Interference. ...www.accessdata.fda.gov/ScienceForums/forum96/A-46.htm - 3k - Cached
• 2002 FDA Science Forum Poster Abstract: U-03 Board U-03. Medical Device Malfunctions Due to Electromagnetic Interference from Metal Detectors: FDA Concerns and Work Toward Solutions ...www.accessdata.fda.gov/ScienceForums/forum02/U-03.htm - 3k - Cached
• 2005 FDA Science Forum Poster Abstract: L-06 ... Background: FDA is concerned that the emissions from some wireless PDAs may causeelectromagnetic interference (EMI) in nearby active medical devices. ...www.accessdata.fda.gov/ScienceForums/forum05/L-06.htm - 3k - 2008-12-23 –Cached
• Interference with Pacemakers and Other Medical Devices ... Radiofrequency energy (RF) from cell phones can interact with some electronic devices.This type of interference is called electromagnetic interference (EMI). ...www.fda.gov/.../HomeBusinessandEntertainment/CellPhones/ucm116311.htm -32k - Cached