U-RHYTHM 4.0 Technical Frequently Asked Questions & Troubleshooting

SET UP ISsueS

1. I do not have the U-RHYTHM program or correct drivers. Download the latest software and drivers from: https://www.dynamic-tx.co.uk/downloads

2. I am having trouble installing the program on my computer/laptop. Right-click the installer and select “Run as administrator”. If unresolved, contact your internal IT support to complete installation.

3. Which time zone is the device synced to? U-RHYTHM is supplied in UK time (UTC). Once synced to your computer, it changes to local time. Sync U-RHYTHM before every use to avoid timestamp confusion. Important: Check settings around daylight saving changes.

4. I do not have the sample log for spool processing. Download it from: https://www.dynamictx.co.uk/resources File name: Microdialysis sample log.pdf

5. What should I do if U-RHYTHM has been inactive for a more than a few weeks? Clean the device and fully charge it (charging can take up to 2.5 hours). Confirm you have the latest software and drivers. If it does not sync, unplug it, close the software, reopen the software, and reconnect. Run a bench test before participant use.

6. The U-RHYTHM LED is blue rather than green. Charge the device. Sync the device with the software.

STARTING TO SAMPLE

1. I used 70% ethanol for soaking MAB connectors instead of 90%. Continue if the MAB connectors attached successfully. 90% ethanol is recommended because it softens MAB connectors more effectively.

2. There is no fluid coming out of the line set adapter, just before I’m ready to connect URHYTHM. Open the pump lid and check the syringe is fitted properly. Close the lid and to start the flush sequence again. Wipe the end of the tubing with gauze or cotton wool.

3. The fluid coming out of the line set adapter is bloodstained. Remove the catheter. Insert a new catheter about 1 cm from the previous site, or on the other side of the umbillicus.

4. The microdialysis membrane was damaged during insertion. Start again with a new catheter. Insert it about 1 cm from the previous site, or on the other side of the umbilicus.

5. The microdialysis membrane is not entirely under the skin, the white membrane is visible. If less than 2mm is exposed, you may continue, but interpret samples with caution. If more than 2 mm is outside the skin, start again with a new catheter.

6. I forgot to wait the 5 minutes for the pump flush sequence to finish before connecting the line set adapter to U-RHYTHM.

If recognised early: Stop the U-RHYTHM device. Disconnect the line set from the U-RHYTHM device. Flush with air for 3 minutes. You may re-sync to the computer, or continue without re-sync (U-RHYTHM can store up to two sampling sessions). Reconnect the line set, ensuring the 5 minute flush sequence has completed.

If not recognised early: This will not damage U-RHYTHM internals. The internals of U-RHYTHM will fill quicker as the flush sequence is 15µl/min. The first sample will be longer and more dilute. The LED will turn green earlier, indicating the session is underway. Data interpretation will be more difficult as sample time stamps will be affected.

7. How quickly should I press the USER button after connecting the line set adapter? Press it as quickly as possible. You can loosely attach the HEX fitting, press USER, then fully tighten.

8. After connecting the line set adapter and pressing the USER button to start the session, the LED shows a single blue flash. How long until a double blue flash? The single blue flash indicates waiting to detect fluid. Double blue flash and low-volume buzzing can appear in a few seconds, or take up to 3 minutes. Double blue flash means the session has started and the device is priming (fluid has started to flow into the device).

9. Why does the time to fill the U-RHYTHM internals vary between sessions? Small manufacturing tolerances across device and pump combinations cause slight variation. Using the same device and pump together should give similar fill time across participant runs.

10. Can I swap the spool outside the official spool swap time window? Yes, but this should be carefully considered in the study protocol. Avoid spool changes around participant interventions or periods when major hormonal changes are expected. Suspend the session directly after bubble insertion to maintain timing consistency. Best practice is to change the spool between 26-30 hours while the LED is flashing blue/green. This uses consumables efficiently by using almost the whole spool.

11. Can I swap the spool without pressing the bubble button? No. Without pressing the bubble-button to enter suspend mode, U-RHYTHM continues for a maximum of 30 hours. After 30 hours, one continuous fluid column will appear as no more bubbles will be inserted. When looking at your data, you can see when the bubble button was pressed as there will be a break in the time stamp log to reflect this.

12. The spool swap process was not finished within 20 minutes. There will be a longer air gap between samples, and the first sample after the spool swap will be shorter. Record this in notes and take extra photos for documentation.

13. Why is sampling limited to 72 hours? The U-RHYTHM device is programmed to accommodate two spool swaps, allowing a maximum of 72 hours of sampling. This limit is set by device battery life.

14. A line has disconnected when the participant returns. End the session. Take photos before removal of the membrane and equipment to see the failure point.

Possible causes: Line tension or pulling, possibly during clothing adjustment; membrane displacement from under the skin (often painless, may go unnoticed) due to excessive tension.

Prevention: Remind participants to keep the wearable positioned at the front of the body; ensure wearable fit is secure but not overly tight; teach participants how to adjust equipment after sleep and during toilet use; keep photos and notes for team learning.

15. I dropped a spool. Dropping can introduce bubbles and sample separation. Take additional care when unrolling the spool, and mark the affected samples. Take extra photos of effected areas. Analyse data with caution.

ENDING A U-RHYTHM SESSION

1. There is a concern about participant discomfort. You can end a session at any time. Press the USER button, cut the tubing with clean surgical scissors, then pull the membrane out in the same direction as insertion.

2. I want to finish sampling early, outside of the spool swap window. Examine the spool in the device. If the fluid is near the black HEX end, press the bubble button to move the fluid along and create space to attach the two haemostat forceps. Press and hold the USER button until U-RHYTHM beeps and the LED turns off.

SAMPLE RETRIEVAL

1. Samples are of varying lengths and/or have air bubbles. This is caused by a range of factors including the participant’s movements and lifestyle, BMI, procedure set up, tiny air bubbles in the perfusion fluid, etc. Document observations in detail to support interpretation. If issue persists, contact DTx: support@dtx.med

2. Bubble lengths between samples vary within the spool. This can occur and may be related to participant activity. Document findings during retrieval. If issue persists, contact DTx: support@dtx.med.

CLEANING U-RHYTHM

1. Can I clean U-RHYTHM device whilst on the charging station? Yes. Note: Pumping fluid into a device that is off may damage it.

2. One of my cleaning lines is stuck in the device. Carefully ease the line out with fine forceps, applying gentle lateral force. Replace cleaning lines after about 10 uses to reduce this risk. If this does not work, contact DTx: support@dtx.med

DOWNLOADING DATA

1. There are error codes at the bottom of the log and I do not know what they mean. These codes are primarily for internal monitoring of device performance. Day to day users should report codes to DTx if U-RHYTHM is not operating as expected.

DISPOSAL OF U-RHYTHM

1. How do I safely dispose of the U-RHYTHM device? Return the device and all accessories to DTx.