The Medicines and Healthcare Products Regulatory Agency (MHRA), United Kingdom posted a medical device safety alert concerning System One S Cycler, manufactured by NxStage.

The manufacturer has identified a software error in the NxStage System One S Cycler Model NX1000-3 or NX1000-3-A, with software versions 4.9 and 4.10. If specific conditions are met and a software error does occur, the ultrafiltration (UF) volume target will not decrease during the treatment even if the UF pump is running. If the software error occurs and remains undetected by the user for a prolonged time, the UF pump may continue to run and remove fluid even after the target UF volume has been removed. Consequently, the patient is at risk for excess fluid removal. If too much fluid is removed, then the patient may develop low blood pressure (hypotension) and experience symptoms such as cramping, nausea, dizziness, blurry vision, or lightheadedness.

The manufacturer is developing a software update to correct the error. Until the software update is implemented, the manufacturer recommends the following:

• Do not turn off the Cycler after priming the cartridge. Only prime the cartridge when ready to start treatment.
• If users experience loss of power or a red alarm greater than "99" during a treatment, end treatment and perform rinseback.
• If users experience a yellow caution 53 Low Fluid Temperature during treatment, either resolve the caution promptly or end treatment and perform rinseback.
• Users should contact healthcare professionals for instructions on restarting the treatment or changing their treatment schedule.

Users can also check the following indications for software error:

• While the number 53 is displayed in the yellow caution window, the software error is occurring.
• If the UF volume target does not change from the original volume target set by the user as treatment progresses, then the Cycler is not performing correctly.

The manufacturer will also be replacing all cyclers for nocturnal patients.

For details, please refer to the MHRA website:
https://www.gov.uk/government/publications/safety-information-from-manufacturers-field-safety-notices/field-safety-notices-2-to-6-october-2015

If you are in possession of the affected products, please contact your supplier for necessary actions.

Posted on 10 November 2015