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What This Guide Helps With
Oxygen calibration fails or displayed oxygen concentration appears incorrect because of gas supply, connections, setup, calibration conditions, or service-level sensing problems.
Step-by-Step Troubleshooting
1. Protect the Patient and Maintain Oxygen Delivery
If oxygen delivery or displayed FiO2 is unreliable during patient ventilation, immediately provide ventilation and oxygen using another verified device or appropriate backup system.
Expected outcome: The patient receives dependable ventilation and oxygen independent of the suspect Servo-c.
2. Confirm the Exact Condition
Determine whether the issue is:
- O2 calibration failure
- Unexpected displayed FiO2
- Unstable oxygen reading
- Oxygen-related pre-use check failure
- Difference between set and measured oxygen concentration
Record the exact displayed message.
Expected outcome: The oxygen-related symptom is clearly defined before adjustments are made.
3. Verify Oxygen and Air Connections
Confirm oxygen and air hoses are connected to the correct ventilator inlets and to verified facility gas sources.
Inspect hoses and fittings for damage, kinks, looseness, or obvious leakage.
Expected outcome: Both required gas supplies are correctly connected and available. If correcting a supply connection resolves the problem, troubleshooting can stop after verification.
4. Check the Facility Gas Source
If gas supply quality or availability is questionable, test another verified outlet or approved source according to facility practice.
Do not assume the ventilator oxygen sensor is faulty until the supply source is verified.
Expected outcome: The external oxygen and air sources are confirmed functional.
5. Inspect the Patient Circuit and Accessories
Check the circuit for leaks, incorrect assembly, open ports, or added devices that could affect the measured gas mixture.
Verify humidification and other respiratory accessories are correctly installed.
Expected outcome: External circuit setup is not affecting oxygen measurement.
6. Repeat the Approved Oxygen Calibration or Pre-Use Check
With verified gas supplies and correct circuit setup, perform the manufacturer-approved calibration or pre-use procedure available through normal operation.
Do not enter unauthorized service menus or force calibration values.
Expected outcome: Oxygen calibration completes successfully. If calibration succeeds and readings remain stable, proceed to final verification.
7. Compare Delivered Oxygen With Approved Test Equipment
Connect the ventilator to an appropriate test lung and approved oxygen analyzer or ventilator analyzer.
Compare the ventilator's displayed oxygen concentration with the independent measurement during controlled ventilation.
Expected outcome: Delivered and displayed oxygen performance is verified as acceptable under the approved test method.
8. Check for Reproducibility
Test more than one oxygen setting within the scope of approved return-to-service testing, if required by local procedure, to confirm the issue is not intermittent.
Expected outcome: Oxygen delivery and measurement remain stable and repeatable.
9. Escalate if Calibration or FiO2 Remains Unreliable
If oxygen calibration continues to fail or measured oxygen remains inconsistent after external gas sources and circuit setup are verified, stop troubleshooting.
Expected outcome: The ventilator is withheld from clinical use until qualified service evaluation is completed.
If the Problem Persists
External gas supplies, hoses, circuit setup, and normal calibration conditions have been ruled out. Remaining causes may involve the oxygen sensing system, internal pneumatic mixing, calibration circuitry, configuration, or other service-level components.
The ventilator should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using appropriate Getinge documentation and approved test equipment
- Repaired or calibrated only by qualified personnel
Perform complete oxygen-delivery, ventilator-performance, alarm, and safety testing before return to service. Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
When FiO2 accuracy is uncertain, do not continue patient ventilation based only on the ventilator display; use a verified alternate ventilator or independent oxygen-monitoring method.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Respiratory Therapy reported that the Servo-c failed oxygen calibration during pre-use testing."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found the oxygen supply hose was connected to an outlet that was not providing the expected gas supply."
Resolution
What action was taken.
Example:
"The ventilator was connected to a verified oxygen source, calibration completed successfully, and oxygen delivery was confirmed with an approved analyzer."
Helpful Details to Include (If Known)
- Exact oxygen-related message
- Set versus displayed FiO2
- Independent analyzer reading
- Oxygen and air source tested
- Hose condition
- Circuit configuration
- Calibration result
- Pre-use check result
- Results before and after correction
- Final device status
Final Thought
Verify external gas supplies and circuit conditions before assuming an oxygen-sensing failure, confirm oxygen delivery independently, and remove the ventilator from service whenever FiO2 cannot be verified.
That is successful troubleshooting.