An electronic key for a body-fluid-removal device “knows” whether or not the tubing and filter have been used, and tracks their period of use. Medical-device manufacturer CHF Solutions, Brooklyn Park, Minnesota, (chfsolutions.com) builds the Aquadex Flexflow system for removing excess fluid from a patient's lungs and lower limbs.

Previous treatments included IV diuretic drugs that could take up to six days to do what the FlexFlow does in eight hours. This can reduce a patient's hospital stay and treatment.

The key, developed by Datakey Electronics Inc. Savage, Minn. (datakeyelectronics.com), must be in place for the unit to function. A detent mechanism on the pump tells when the key is properly inserted. The tubing, filter, and key are tethered together and disposable. The key contains a nonvolatile eeprom memory with data that defines an appropriate treatment to the console. For one thing, the key identifies a lot number of the tubing and filter. If the device recognizes the lot number, it starts treatment. The eeprom also tracks when treatment starts and how long the tube and filter are used. The key prevents from using the tubing and filter more than once.

Each tube and filter set is programmed for eight hours of use. An attending nurse is notified after that period and makes the clinical decision to end or continue.