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Manufacturer
Model
What This Guide Helps With
Helps isolate sensor installation, contamination, connection, circuit, calibration-condition, or external accessory problems when flow measurement is absent or calibration will not complete.
Step-by-Step Troubleshooting
1. Protect the Patient
Do not troubleshoot an unreliable flow measurement system while a patient depends on the affected monitoring or ventilation function. Use an alternate verified anesthesia machine or monitoring method as clinically appropriate.
Expected outcome: Patient care continues safely while the Fabius is evaluated.
2. Confirm the Exact Failure
Determine whether the flow value is absent, fixed, erratic, obviously incorrect, or whether a calibration attempt fails.
Reproduce the problem off-patient under an approved test configuration.
Expected outcome: The specific flow-sensor symptom is confirmed.
3. Inspect Sensor Installation
Inspect the externally accessible flow sensor and associated breathing-system components. Confirm correct orientation, seating, and assembly.
Look for:
- Loose installation
- Reversed placement
- Damaged housing
- Improperly fitted connections
- Missing components
Expected outcome: The flow sensor is installed correctly. If reseating restores a stable reading, proceed to verification.
4. Check for Moisture or Contamination
Inspect the accessible sensor pathway for condensation, fluid, debris, or contamination that could interfere with measurement.
Handle and clean only in accordance with approved manufacturer procedures. Do not improvise cleaning methods.
Expected outcome: The sensor pathway is clean and dry enough for valid operation. If correcting an approved external contamination issue restores measurement, continue to final testing.
5. Inspect External Sensor Connections
Check associated electrical connectors, pneumatic tubing, or accessible sensor interfaces as applicable. Look for looseness, bent contacts, strain, or visible damage.
Expected outcome: All external sensor connections are secure and undamaged.
6. Verify Calibration Conditions
Confirm the breathing system is assembled correctly and placed in the proper non-patient condition required for the approved calibration process.
Do not use undocumented calibration sequences or service menus.
Expected outcome: Calibration is attempted only under valid conditions. If calibration succeeds, proceed to functional verification.
7. Substitute a Known-Good Compatible Sensor
If permitted and available, test with a compatible known-good flow sensor or approved external component.
Expected outcome: If the known-good component calibrates and measures correctly, the original sensor or associated external component is identified as defective and can be replaced.
8. Compare Flow With Test Equipment
Use approved anesthesia or ventilator test equipment to confirm whether gas flow is actually present and whether displayed flow follows expected changes.
Expected outcome: The distinction between a true flow-delivery problem and a measurement problem is established.
9. Perform Final Verification
After correction, complete the applicable calibration and functional checks. Verify stable flow readings, tidal-volume behavior, ventilation, and alarm response with a test lung.
Expected outcome: Flow measurement is stable and appropriate throughout testing. If so, troubleshooting is complete.
10. Escalate if Calibration Still Fails
If the sensor is correctly installed, external connections are intact, known-good components do not resolve the issue, and calibration still fails, stop external troubleshooting.
Expected outcome: The machine is removed from service and escalated for internal diagnostic evaluation.
If the Problem Persists
External installation, contamination, sensor, circuit, and calibration-condition causes have been ruled out. Remaining possibilities may involve internal signal processing, pneumatic sensing, calibration storage, interface electronics, or other service-level functions.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using appropriate manufacturer documentation and approved test equipment
- Repaired or calibrated only by qualified personnel
Complete applicable ventilation, flow, volume, alarm, and safety checks before return to service.
Clinical Use Tip
Do not rely on displayed tidal volume when the flow-measurement system is known to be unreliable; move the patient to a verified monitoring and ventilation system first.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Anesthesia staff reported no flow reading and an unsuccessful flow-sensor calibration during setup."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found the external flow sensor was not fully seated in the breathing-system assembly."
Resolution
What action was taken.
Example:
"The sensor was correctly reseated, calibration completed successfully, and flow and ventilation performance were verified with approved test equipment."
Helpful Details to Include (If Known)
- Exact flow symptom
- Calibration result
- Sensor orientation
- Moisture or contamination observed
- Connector condition
- Known-good sensor result
- Analyzer comparison
- Ventilation behavior
- Alarm behavior
- Final device status
- Exact flow symptom
- Calibration result
- Sensor orientation
- Moisture or contamination observed
- Connector condition
- Known-good sensor result
- Analyzer comparison
- Ventilation behavior
- Alarm behavior
- Final device status
Final Thought
A failed flow calibration does not automatically indicate an internal fault. Confirm installation, cleanliness, connections, calibration conditions, and known-good external components first, then escalate with objective test results when the problem remains.
That is successful troubleshooting.