2025-10-10 – Weekly Medical Equipment News : Pressure sensor drift mystery

Last week, our community engaged in some thought-provoking discussions. A key focus was the unexpected drift in pressure sensors when used with saline, sparking a technical exchange on troubleshooting methods. There was also significant interest in the value of certification programs for biomedical equipment professionals, as members weighed the benefits against the costs. Many shared their career journeys, offering insights into first jobs and essential tools for medical equipment technicians.


This Week’s Hot Topics

Unexpected pressure sensor drift in saline
The discussion delves into troubleshooting techniques for pressure sensors that show drift when used with saline, a topic crucial for maintaining equipment accuracy.
Read more here

Are Biomedical Equipment Certification Programs Worth It?
A lively debate on whether certification programs provide a significant career boost or if experience holds more value.
Read more here

Best Forums and Communities for Equipment Professionals
Members shared their favorite online spaces for connecting with peers, a great resource for anyone looking to expand their network.
Read more here

What Was Your First Job in the Medical Equipment Field?
An engaging thread where professionals reminisce about their early career roles, providing both nostalgia and advice for newcomers.
Read more here

What’s the Most Widely Used Medical Device in the U.S.?
This topic explores the prevalence of different medical devices, sparking curiosity about which ones are most common.
Read more here

Do You Know the Inventor Behind the MRI Machine?
A fascinating dive into the history of the MRI machine and the inventor’s contributions to medical technology.
Read more here

What’s In Your Toolkit as a Medical Equipment Technician?
Professionals share the must-have tools in their kits, a handy reference for anyone in the field.
Read more here

FAQ/Guidelines
A useful thread for understanding the forum’s guidelines and frequently asked questions.
Read more here

Admin Guide: Getting Started
Essential reading for new administrators looking to get up to speed with forum management.
Read more here

Curious About a Career in Medical Equipment? Here’s Where to Start
An invaluable resource for anyone considering entering the field of medical equipment, offering tips and guidance.
Read more here


Looking forward to another week of engaging discussions. Keep sharing your expertise and questions!

We chased the same “saline drift” last week and found micro‑wicking into the reference port; adding a hydrophobic 0.2 µm vent filter plus a small drip loop and giving it 5–10 minutes to thermally settle before zeroing stopped it… If it’s a media‑isolated gel sensor that won’t help — check the datasheet’s saline/chloride note and tempco; TE’s overview is solid: https://www.te.com/usa-en/industries/sensors/insights/media-compatibility-pressure-sensors.html.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​​​⁠​‌​⁠​​​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌​⁠‌‌⁠​⁠‌⁠‍​‌‍‌⁠‌​​‌‌​⁠⁠‌‍​‍‌⁠‌​‌‌⁠⁠‌‍‌​‌​‌​‌‌​​‌​‌⁠‌​‌‌​⁠​‌‌‌​‍​‍​‍‌⁠⁠‌

On our anesthesia carts, the ‘saline drift’ mostly vanished after we started degassing the bag for 60–90 seconds with a [redacted] syringe before priming. Microbubbles were creeping into the sensor and mimicking baseline shift; a warm bag helps, but the quick syringe pull has been more reliable. If you can’t do that in the field, let the line warm and run a slow 1–[redacted]/min flush for a minute before zeroing.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​​​⁠​‌​⁠​‍​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍​⁠‌​‌⁠​‌‌⁠‌​‌⁠‌‍‌​‌⁠​⁠‍​‌​⁠‍‌‍‌​‌​‍‍‌‍‍‍‌‌‌​‌⁠‍​‌​‍​‌‍‍​‌​‍‍‌‍⁠‌​‍​‍‌⁠⁠‌

Noticed our offsets dropped a lot after we stopped taping the transducer to a warmer — moving it off the heat and giving it 3–5 minutes to thermally settle fixed it; if relocating isn’t practical, a small foam sleeve buffered the swings, @m_reyes203.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​​​⁠​‌​⁠​⁠​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌⁠‌‍​⁠​⁠‌​​⁠‌​‍‌‌​‍‍‌​⁠⁠‌⁠‌​​⁠‌‍​⁠​‍​⁠‌‍‌‌​​​⁠‍‌‌​‌⁠​⁠​‌​⁠‌⁠‌​​‍​‍​‍‌⁠⁠‌

Last week we traced ours to the pressure bag creeping past “300 mmHg” during long cases, which preloaded the dome and let the reading wander. We standardized to 250–275 and swapped out two sketchy bag gauges; a quick A/B with a known‑good bag nailed it. If that’s not it, a barely‑seated monitor connector can look like drift.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​​​⁠​‌​⁠‌‌​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍​⁠​‍‌‌​⁠​⁠​⁠‌‍‌​‌⁠​‍‌‌‌​‌‍‍​‌​​⁠‌⁠‍​‌‍​‍‌⁠‍‍‌​‍‍‌​⁠‍‌‍‌⁠‌​‍‍‌​‍⁠​‍​‍‌⁠⁠‌

We chased a similar wander and it turned out we were over‑tightening the disposable dome on the reusable transducer; switching to the IFU torque (“hand‑tight plus a quarter turn”) stopped the offset from creeping during cases. If your kit is a fixed‑dome type this won’t apply, but on mixed fleets I put a small paint mark on the ring as a visual torque cue, @JennaC.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​​​⁠​‌​⁠‌‍​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌‍​‍‌⁠​​‌‍‌⁠‌‌‌​‌‌‌​​⁠​​‌​‍⁠‌​‍‍‌‍‍⁠​‍⁠‌‌​⁠⁠‌‌​‌‌‌​‌​⁠​‌‌​‍​‌‌​​​‍​‍‌⁠⁠‌

Quick find for us: the “mystery drift” was a wet vent filter on the reference port — splash during priming meant the transducer equalized painfully slow and the baseline crept 10–15 minutes. We now zero only after confirming the vent is dry and uncovered, and if the filter looks foggy we swap the dome; otherwise you chase ghosts. Edwards’ TruWave IFU even flags this: https://www.edwards.com/devices/pressure-monitoring/truwave.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​​​⁠​‌​⁠‌⁠​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌⁠​​‌​‍‍​⁠​⁠‌⁠‍‍‌‍⁠‍‌⁠‌​‌⁠‍‍​⁠​​‌⁠​​‌⁠‌⁠​⁠‌⁠​⁠‌​‌‍‌⁠‌​⁠‌‌‌‌​‌⁠​​​‍​‍‌⁠⁠‌

And noticed saline drift when IV pole height changed; re-zero at ‘mid-axillary’ fixed most, microbubbles sometimes mimic it.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​​​⁠​‌​⁠‍​​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍​⁠‌‍​‍⁠‌​⁠‌‌‌​‍​​⁠‌‌‌​⁠‌‌⁠‌‍‌⁠‍​‌‍⁠‍‌‍​⁠‌‌⁠⁠‌⁠​⁠‌⁠​​‌‌‌‍‌‍‌⁠‌‍‌​​‍​‍‌⁠⁠‌

Saw “unexpected drift” with saline when the flush bag and transducer came straight from a cold storeroom — . Letting it sit 5–10 minutes to warm up before zeroing fixed it consistently; if that doesn’t help, make sure the pressure bag’s really at 300 mmHg and not bleeding off. Have you tried a short warm-up before zero?

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​​​⁠​‌​⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌⁠‍‌‌‌‍​​‍⁠‌‌‌​​‌⁠‌‌‌​‌​‌⁠‍‍​⁠‌​‌‍​⁠‌​⁠⁠​⁠‌‌‌​‌‍​⁠‌⁠‌‍‌⁠‌​‍⁠​‍​‍‌⁠⁠‌

Had one case where the ‘drift’ wasn’t fluid at all — wrong transducer/cable family, so the monitor read the ID resistor wrong and the baseline wandered; swapping to the correct cable fixed it. Quick sanity check: match the transducer part number to the monitor’s setting and keep the reference truly vented as @d_roberts78 flagged. the wrong phone charger problem for pressure lines.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​​​⁠​‍​⁠​‌​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌​⁠​‌‍‌​‌‌​⁠‌​​‌‌‌‍​‌‌​‍​‍⁠‌​⁠​⁠‌‍‍‍‌‌‍‌‌⁠‍​‌‍​‍​⁠‍​‌‌‌​‌​⁠‌‌‌‌‍​‍​‍‌⁠⁠‌

Saw the pressure bag creep bite us — gauge looked fine at setup but sagged to about 180 mmHg over an hour, and the saline line showed a slow baseline crawl. Pumping it back to a firm 300 and doing a quick square-wave/fast flush made the “unexpected drift” disappear. If that’s not it, a slightly sticky stopcock can mimic it.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​​​⁠​‍​⁠‌⁠​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌⁠‌‌‌‍⁠‍​⁠‌​‌‌‍‌‌⁠‌​‌⁠​‍‌‌‍‌‌​​⁠‌⁠‍‌‌⁠​​​⁠​‌‌‍⁠⁠​‍⁠‌‌‌‌⁠​⁠​‌‌‍⁠‌​‍​‍‌⁠⁠‌

We chased a slow baseline wander to the transducer holder gradually slipping a few millimeters on the pole as the tubing tugged; a tiny zip tie on the bracket and re-leveling after line or bed moves stopped it. @d_gibson22 ever see clamp creep masquerade as “drift”?

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​​​⁠​‍​⁠‍​​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍​⁠​​‌⁠​‌‌​‍‌‌​⁠⁠‌​‍‌‌‍​‌​⁠‌⁠‌‍⁠‌‌​​⁠‌‍‍‍‌⁠‌‌‌‍‍‌‌​‌‍‌‌‍​‌‍⁠​‌⁠​​​‍​‍‌⁠⁠‌

In my shop, that “drift in pressure sensors when used with saline” turned out to be a wet hydrophobic vent on the zeroing stopcock; once the filter wicked saline, the baseline drifted until we swapped the cap and re-zeroed. I flick the vent and make sure it’s dry before zero, and replace the transducer if the vent looks contaminated — small caveat: frequent flushes or fluid warmers make this more likely, so watch the vent during setup.

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍‌‌‌‍‌​‌‍‍‌‌‍​⁠‌‍​‌‌‍⁠​‌‍‌‌‌⁠​‌‌⁠‌‌‌‍‍‌‌⁠​​‌‍⁠‌‌‍‌‌‌‍⁠‍‌⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌⁠​‍‌‍‌‌‌⁠​​‌‍⁠​‌⁠‍‌​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​⁠​‌​⁠​‍​⁠​​​⁠‌⁠​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​‌​⁠​​​⁠​⁠​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌‍⁠‌‌‍⁠​‌​‌​‌‍⁠⁠‌‌​‍‌​⁠​‌​⁠‍‌‌​​‌​⁠‌‌⁠​⁠‌‌‌‍‌​‍‍​⁠‌‍‌‍​‌‌​⁠​‌‍‍‌​‍​‍‌⁠⁠‌