Study: Surgical magnets may affect iPads in the shunt valve settings
Exposure to tablet devices may alter programmable shunt valve settings, based on the results of research published June 26 in the Journal of Neurosurgery: Pediatrics.
Jennifer Strahle, MD, department of neurosurgery ay the University of Michigan in Ann Arbor, and colleagues investigated the effect of a tablet computer on performance-level settings of a programmable shunt valve using magnetic field strength near the tablet with and without a cover; recorded at distances between 0 mm and 100 mm.
“Normally, external magnetic programming tools can change valve settings by interacting with a magnetic rotor inside the valve,” wrote the authors. “There have been multiple reports of environmental magnetic field exposures changing adjustable valve settings.”
The researchers used the iPad 2 and the iPad 2 Smart Cover to determine the effect of this tablet on magnetically programmable shunt valves. Programmable valves were exposed to the tablet device at distances of less than 1 cm, 1–2.5 cm, 2.5–5 cm, 5–10 cm and greater than 10 cm. For each distance tested, the valves were exposed 100 times to the tablet with the cover, resulting in 500 total valve exposures. The tablet alone, without the cover, was also tested at distances of less than 1 cm for 30 valve exposures. Changes in valve performance-level settings were recorded.
The maximum recorded magnetic flux density of a tablet with a cover was 17.0 mT, and the maximum recorded magnetic flux density of the tablet alone was 7.6 mT. In 100 exposures at distances between 0 and 1 cm, 58 percent of valves had different settings following exposure, the authors found.
At distances greater than 1 cm but less than 2.5 cm, 5 percent of valves in 100 exposures had setting changes. Only a single setting change was noted in 100 exposures at distances greater than 2.5 cm but less than 5 cm. “No setting changes were noted at distances greater than 5 cm, including 100 exposures between 5 and 10 cm, and 100 exposures of more than 10 cm. For the 30 valve exposures to the tablet without a cover, 20 valve performance-level changes (67 percent) were noted.”
“While our data do not support any significant interaction between the tablet computer and the programmable shunt valve at distances greater than several centimeters, patients and their caregivers should be warned of the potential for this interaction when the iPad 2 is in very close proximity to the magnetically programmable shunt valve,” the authors concluded. “With proper precautions to keep a tablet device away from close proximity to the valve, the continued use of these devices, even in the general vicinity of patients with programmable shunt valves, appears to be safe. Finally, it should be noted that magnetic field strength of the iPad 2 is within the range of other household magnets. General precautions taken with the iPad 2 should reflect common precautions taken with other household magnets.”
Jennifer Strahle, MD, department of neurosurgery ay the University of Michigan in Ann Arbor, and colleagues investigated the effect of a tablet computer on performance-level settings of a programmable shunt valve using magnetic field strength near the tablet with and without a cover; recorded at distances between 0 mm and 100 mm.
“Normally, external magnetic programming tools can change valve settings by interacting with a magnetic rotor inside the valve,” wrote the authors. “There have been multiple reports of environmental magnetic field exposures changing adjustable valve settings.”
The researchers used the iPad 2 and the iPad 2 Smart Cover to determine the effect of this tablet on magnetically programmable shunt valves. Programmable valves were exposed to the tablet device at distances of less than 1 cm, 1–2.5 cm, 2.5–5 cm, 5–10 cm and greater than 10 cm. For each distance tested, the valves were exposed 100 times to the tablet with the cover, resulting in 500 total valve exposures. The tablet alone, without the cover, was also tested at distances of less than 1 cm for 30 valve exposures. Changes in valve performance-level settings were recorded.
The maximum recorded magnetic flux density of a tablet with a cover was 17.0 mT, and the maximum recorded magnetic flux density of the tablet alone was 7.6 mT. In 100 exposures at distances between 0 and 1 cm, 58 percent of valves had different settings following exposure, the authors found.
At distances greater than 1 cm but less than 2.5 cm, 5 percent of valves in 100 exposures had setting changes. Only a single setting change was noted in 100 exposures at distances greater than 2.5 cm but less than 5 cm. “No setting changes were noted at distances greater than 5 cm, including 100 exposures between 5 and 10 cm, and 100 exposures of more than 10 cm. For the 30 valve exposures to the tablet without a cover, 20 valve performance-level changes (67 percent) were noted.”
“While our data do not support any significant interaction between the tablet computer and the programmable shunt valve at distances greater than several centimeters, patients and their caregivers should be warned of the potential for this interaction when the iPad 2 is in very close proximity to the magnetically programmable shunt valve,” the authors concluded. “With proper precautions to keep a tablet device away from close proximity to the valve, the continued use of these devices, even in the general vicinity of patients with programmable shunt valves, appears to be safe. Finally, it should be noted that magnetic field strength of the iPad 2 is within the range of other household magnets. General precautions taken with the iPad 2 should reflect common precautions taken with other household magnets.”