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What This Guide Helps With
Troubleshooting failed oxygen-sensor calibration, inaccurate inspired-oxygen readings, unstable FiO2 values, or oxygen-monitoring errors caused by setup, gas supply, sampling, or sensor issues.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not calibrate or troubleshoot the oxygen-monitoring system while the Avance is supporting an active patient.
If the displayed FiO2 is missing, unstable, or inconsistent with the selected gas mixture:
- Notify the anesthesia provider immediately.
- Use an approved independent oxygen analyzer.
- Transfer the patient to another verified anesthesia machine when reliable oxygen monitoring cannot be confirmed.
- Follow the facility’s anesthesia-machine failure procedure.
Expected: Patient care no longer depends on equipment with questionable oxygen measurement.
If the patient is safely supported elsewhere, continue troubleshooting in a controlled Clinical Engineering setting.
2. Confirm the Exact Failure
Review the reported message and determine whether the problem involves:
- O2 sensor calibration failure
- Calibration required
- FiO2 reading higher or lower than expected
- FiO2 value drifting or fluctuating
- Missing oxygen reading
- Reading that does not respond to changes in oxygen concentration
Record the complete displayed message and the conditions present when it occurred.
Expected: The failure is clearly identified before components or settings are changed.
3. Allow the System to Complete Startup
Power the Avance on using a verified electrical outlet and allow it to complete its normal startup sequence.
Do not attempt calibration while the system is still initializing or displaying unresolved startup alarms.
Expected: The machine completes startup without unrelated power, gas-supply, or system-check errors.
If a broader startup or system failure is present, troubleshoot that condition before evaluating the oxygen sensor.
4. Verify the Medical-Gas Supplies
Confirm that:
- The oxygen pipeline hose is securely connected.
- The wall outlet is supplying oxygen.
- The pipeline-pressure indication is within the facility’s acceptable range.
- Backup oxygen-cylinder pressure is adequate.
- Air and nitrous-oxide hoses are connected to the correct indexed outlets.
- No gas-supply alarms are active.
Use an approved independent method to verify the gas source when the pipeline supply is questionable.
Expected: The Avance has stable and correctly connected medical-gas supplies.
If correcting the supply resolves the FiO2 error, complete an operational check and stop.
5. Inspect the Breathing System
Check the accessible breathing-system components for:
- Loose inspiratory or expiratory connections
- Incorrectly installed breathing circuit
- Open sampling ports
- Disconnected reservoir bag
- Improperly seated absorber canister
- Damaged hoses or fittings
- Excessive leakage
- Incorrect auxiliary gas outlet configuration
A significant leak or incorrect circuit configuration can prevent a stable oxygen concentration from reaching the measurement system.
Expected: The breathing system is correctly assembled and free of obvious external leaks.
If correcting the circuit resolves the reading, complete the required system test and stop.
6. Check the Gas-Sampling Path
Inspect the external sampling components, when equipped, including:
- Sample line connections
- Water trap installation
- Water trap fill level
- Kinked or occluded tubing
- Moisture or contamination
- Loose connections at the patient circuit and gas module
- Exhaust or scavenging tubing that may be restricted
Replace suspect disposable sampling components with compatible, known-good items.
Expected: Gas can travel through the sampling path without leakage, moisture blockage, or restriction.
If the FiO2 reading becomes stable after replacing a sampling component, verify operation and stop.
7. Inspect the Accessible O2 Sensor Components
With the machine removed from clinical use, inspect the externally accessible oxygen-sensor location and connections.
Check for:
- Loose or partially seated sensor
- Damaged connector or cable
- Moisture around the sensor
- Contamination
- Cracked housing
- Bent or damaged contacts
- Incorrect or incompatible replacement sensor
- Sensor installation that does not match the device configuration
Do not open sealed sensor assemblies or perform internal board-level work.
Expected: The oxygen sensor and its accessible connections are clean, dry, compatible, and securely installed.
If reseating an approved accessible connection resolves the problem, repeat the operational check and stop.
8. Confirm Calibration Conditions
Place the machine in the required nonclinical operating condition and ensure the sensor is exposed to the correct calibration gas environment.
Before starting calibration:
- Remove the machine from patient use.
- Confirm stable gas supplies.
- Allow the oxygen reading to stabilize.
- Ensure the breathing and sampling systems are correctly configured.
- Prevent residual high-oxygen mixtures or anesthetic gas from affecting the calibration environment.
- Follow the facility-approved procedure and the applicable GE Healthcare instructions for the installed software and sensor configuration.
Expected: Calibration is attempted only after the measurement environment is stable and known.
The Avance uses oxygen monitoring as part of its gas-measurement system, so inaccurate calibration conditions can produce an incorrect displayed value.
9. Perform the Approved O2 Sensor Calibration
Run the user-accessible oxygen-sensor calibration from the normal calibration or checkout menu.
Observe whether the calibration:
- Completes successfully
- Times out
- Produces an unstable-value message
- Reports a sensor failure
- Returns immediately to calibration required
Do not repeatedly recalibrate a sensor that continues to fail under verified conditions.
Expected: Calibration completes and the displayed oxygen value stabilizes at an appropriate reading for the test gas.
If calibration succeeds, continue to functional verification.
10. Compare the Reading With an Independent Analyzer
Connect a calibrated external oxygen analyzer using an approved test setup.
Test the Avance with controlled oxygen concentrations appropriate for the facility’s verification procedure. Compare the machine’s displayed FiO2 with the independent analyzer after both readings stabilize.
Expected: The Avance reading tracks changes in oxygen concentration and remains within the manufacturer’s applicable tolerance.
If the machine reading is inaccurate while the independent analyzer remains stable, suspect a deteriorated sensor, gas-module problem, connection fault, or internal measurement failure.
11. Substitute Approved External Components
When permitted by facility policy, substitute one external component at a time:
- Known-good compatible oxygen sensor
- Known-good sample line
- Known-good water trap
- Known-good gas-analysis module, if externally interchangeable
- Known-good breathing circuit
Repeat calibration or verification after each substitution.
Expected: The defective external component is isolated without unnecessary internal disassembly.
If a known-good oxygen sensor calibrates and measures correctly, replace the original sensor and document the result.
12. Complete Final Operational Verification
After calibration or component replacement:
- Run the required system checkout.
- Confirm the oxygen reading is present and stable.
- Change the delivered oxygen concentration and verify that the displayed FiO2 responds appropriately.
- Confirm oxygen alarms activate as expected using the facility-approved test method.
- Verify there are no active gas-monitoring or calibration messages.
- Compare the displayed value with an independent calibrated oxygen analyzer.
Expected: The Avance passes checkout and provides stable, credible oxygen measurement before being returned to service.
If the Problem Persists
If calibration continues to fail or the FiO2 reading remains inaccurate after gas supplies, circuit configuration, sampling components, sensor seating, calibration conditions, and approved external substitutions have been checked, common external causes have been ruled out.
The issue may involve the oxygen-sensor interface, gas-analysis module, internal pneumatic path, signal processing, wiring, or control electronics.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using current GE Healthcare service documentation and approved test equipment
Knowing when to stop external troubleshooting and escalate the repair is proper Clinical Engineering practice.
Clinical Use Tip
Never rely on a questionable FiO2 reading during patient care. Move the patient to verified equipment or use an approved independent oxygen analyzer before troubleshooting the Avance.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Anesthesia staff reported that the GE Healthcare Avance displayed an O2 sensor calibration failure and an unstable FiO2 reading."
Cause
What was observed during troubleshooting.
Example:
"Inspection found moisture in the gas-sampling water trap and a restricted sample line, preventing stable oxygen measurement during calibration."
Resolution
What action was taken.
Example:
"Replaced the water trap and sample line, completed O2 sensor calibration, verified the reading against a calibrated external oxygen analyzer, and returned the machine to service."
Helpful Details to Include (If Known)
- Outlet tested
- Pipeline oxygen pressure verified
- Backup-cylinder pressure
- Exact displayed message
- O2 sensor age or replacement date
- Calibration result
- Sample line and water trap condition
- Breathing-system leak-test result
- Independent analyzer reading
- FiO2 response at different oxygen concentrations
- Indicator lights or additional alarms
- Unusual heat, sound, odor, or moisture
- Components substituted
- Final device status
Final Thought
Reliable oxygen monitoring is essential to safe anesthesia delivery. Begin with patient protection, verify gas supplies and external components logically, use an independent analyzer, and escalate unresolved measurement failures with complete CCR documentation.
That is successful troubleshooting.