Do hospital IT departments plan and deploy WLANs without considering
impacts on medical devices? Rumblings that I've heard suggest that some
do. I'd love to hear your perspectives on that question, via comments
below or email.
The obvious concern is the risk of radio frequency (RF) interference on
medical devices. The good news is that the risk of interference is
negligible - the low transmit power of 802.11 radios minimizes
interference risks. Coexistence with medical devices and other wireless
devices is a clear risk, but an issue for another time.
This post focuses on a more important consideration in WLAN
planning: plans for future wireless medical devices. Planning
issues discussed include selecting wireless bands, private vs. shared
infrastructure, coverage, security, and some of the risks of inadequate
In the patient monitoring market, WMTS predominates. Exceptions include Welch Allyn who uses 802.11FH (frequency hopping), and GE who uses the same for their multi parameter patient monitors. Draeger uses whatever flavor of 802.11 the hospital wants to use. Philips uses their new DECT-based WMTS for telemetry and patient monitors (excluding the M70).
All the smart pump vendors are using 802.11b. You can expect wireless spot vital signs monitors, like Stinger's, to all use 802.11. I know of a number of medical device vendors who are developing next generation radios that use 802.11a.
The other big issue is private vs. shared infrastructure. Many of the
monitor vendors insist on private subnets for their wireless devices
(although they will relent if pressed). Draeger has leapfrogged the
competition with a patient monitor network that runs on the hospital's
infrastructure. I believe Draeger's approach will eventually become the
industry standard for all medical devices, including telemetry.
When it comes to coverage, plan on covering patient care and diagnostic
areas 100 percent. Even if you're starting with meds administration and
only need to cover hallways, it won't be long before applications
extend into patient rooms, bathrooms, waiting rooms, and beyond.
Traditionally, wireless medical devices have depended heavily on
obscurity to provide security. The new digital WMTS implementations
from GE and Philips have implemented more robust security. The recent
approval and commercial availability of products using 802.11i,
combined with 802.11x authentication provide health care with an
industry standard that can support interoperability and multi vendor
(i.e., medical devices from different vendors) deployments. Sure, some
applications like updating formularies on smart pumps don't require
security, but it won't be long before applications like alarm
notification will dominate, so plan ahead. I know of at least one pump
vendor who's developing a replacement radio because security
requirements changed with the advent of applications using patient
Finally there is the question of how to coordinate WLAN requirements
and planning with those that can be impacted -- nursing and biomedical
The risk in not considering the impact of medical devices is not that
things won't work (or will stop working), but that you'll have to
replace or duplicate expensive infrastructure in 2 to 4 years -- way
before its time. Going into ceilings and just touching APs, let alone
installing, moving or replacing them can be very expensive on a house
wide basis. (A potential alternative to ceiling mounted APs is Innerwireless.)
For more info, you can use the Google search box in the right column
near the bottom of this page for more posts on these topics. You might
want to try "WMTS", "ISM", and "802.11" as search terms. In the left
hand column try the Networking and Flexible Monitoring categories.