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What This Guide Helps With
Use this guide when arterial or venous pressure appears inaccurate, unstable, absent, or inconsistent due to tubing, transducer interfaces, setup, or sensing faults.
Step-by-Step Troubleshooting
1. Protect the Patient From Unreliable Pressure Monitoring
Do not continue treatment when arterial or venous pressure monitoring is unreliable and the cause cannot be immediately identified. Move the patient to another verified machine when necessary before technical troubleshooting.
Do not defeat pressure alarms or alter limits to conceal an abnormal reading.
Expected outcome: The patient is not dependent on unreliable pressure monitoring.
2. Confirm Which Reading Is Affected
Determine whether the arterial pressure, venous pressure, or both are affected. Establish whether the reading is absent, fixed, fluctuating, offset, or simply inconsistent with the clinical situation.
Record the displayed values and any associated alarm message.
Expected outcome: The specific measurement problem is clearly defined.
3. Inspect the Bloodline and Pressure Tubing
With the machine out of patient use, inspect the applicable pressure line and bloodline for kinks, clamps, occlusions, loose fittings, leaks, fluid intrusion, collapsed tubing, or incorrect routing.
Expected outcome: Tubing and pressure pathways are correctly routed, open where intended, and securely connected.
4. Check the Pressure Interface
Inspect the external pressure connection or interface for proper seating and physical damage. Confirm the applicable line is fully connected and not partially detached.
Do not access or adjust internal pressure sensors.
Expected outcome: The external pressure interface is correctly assembled. If reconnecting it restores a plausible stable reading, continue to verification and stop troubleshooting.
5. Verify Disposable Installation
Confirm the approved disposable bloodline set is installed correctly and that pressure monitoring components are in their intended positions.
Compare with a properly configured known-good machine if uncertainty exists.
Expected outcome: Disposable setup matches normal configuration and no installation error is present.
6. Replace Questionable External Components
When appropriate, repeat testing with a known-good compatible bloodline or pressure monitoring component. Do not reuse components suspected of leakage, contamination, or deformation.
Expected outcome: The problem either follows the disposable component or remains with the machine. If a known-good component restores normal pressure measurement, replace the affected disposable and stop troubleshooting after verification.
7. Check for Mechanical Causes During Simulated Operation
Using an approved nonpatient test setup, observe whether the reading responds logically to expected changes in the circuit. Ensure clamps, pumps, tubing, and circuit routing are not creating an artificial pressure condition.
Expected outcome: Pressure readings respond in a stable and plausible manner to changes in the test setup.
8. Perform Final Functional Verification
Verify the arterial and venous pressure channels display stable, plausible values and associated alarms or protective responses function as required by approved testing.
Do not return the device to clinical service if a pressure channel intermittently freezes, drifts, or behaves unpredictably.
Expected outcome: Both pressure measurements operate consistently through final testing. Troubleshooting can stop.
If the Problem Persists
If bloodline routing, pressure tubing, disposable installation, external connections, and known-good substitutions have been ruled out, the problem may involve an internal pressure sensor, pneumatic pathway, signal-processing circuit, calibration, or control function.
The device should be:
- Removed from service.
- Labeled Out of Service.
- Sent for repair or bench evaluation.
- Evaluated using approved test equipment and Fresenius Medical Care documentation.
- Calibrated or repaired only by qualified personnel.
- Subjected to applicable pressure-monitoring and alarm verification before return to service.
Reliable arterial and venous pressure monitoring is essential; unresolved inaccuracy requires escalation.
Clinical Use Tip
A pressure value that looks believable but does not respond normally to circuit changes should still be treated as unreliable until verified.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Dialysis staff reported the venous pressure reading on the 5008S CorDiax was intermittently low and unstable during setup."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found the external pressure line connection was loose and intermittently venting."
Resolution
What action was taken.
Example:
"The connection was secured, pressure response was verified with a nonpatient functional test, and the machine was returned to service."
Helpful Details to Include (If Known)
- Arterial, venous, or both channels affected.
- Displayed values and alarm messages.
- Bloodline routing.
- Pressure tubing condition.
- Connection condition.
- Fluid intrusion or leakage.
- Known-good disposable substitution.
- Response during nonpatient testing.
- Final device status.
Final Thought
Pressure-monitoring problems should be worked from the disposable circuit inward, verifying tubing and connections before suspecting a sensor and escalating any unresolved or intermittent measurement problem.
That is successful troubleshooting.