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What This Guide Helps With
Addresses unsuccessful oxygen calibration or questionable FiO2 readings caused by gas supply, connections, configuration, leaks, or sensing-related faults.
Step-by-Step Troubleshooting
1. Protect the Patient and Verify Oxygenation Independently
Do not troubleshoot questionable oxygen delivery while a patient depends on the affected ventilator. Transfer the patient to another verified ventilator when delivered oxygen concentration cannot be trusted.
Use appropriate independent clinical monitoring during any equipment exchange.
Expected outcome: The patient is supported by equipment with verified oxygen delivery.
2. Confirm the Reported Condition
Determine whether the problem is a failed oxygen calibration, an unexpectedly high or low displayed FiO2, unstable readings, or disagreement with another measurement.
Record any displayed message and the conditions under which the problem occurs.
Expected outcome: The exact oxygen-related failure is identified and reproducible.
3. Verify Oxygen and Air Sources
Confirm that both required gas supplies are connected to the intended inlets and that hoses are securely attached.
Inspect the hoses and fittings for damage, kinks, loose connections, or accidental interchange.
Expected outcome: Air and oxygen supplies are correctly connected and externally intact. If correcting a supply connection restores normal operation, proceed to final verification.
4. Check the Facility Gas Source
Verify the affected wall outlet or source using an appropriate facility-approved method. If practical, compare the ventilator on another known-good gas source.
Do not assume the ventilator is defective when the infrastructure has not been ruled out.
Expected outcome: The external oxygen and air sources supplying the ventilator are verified.
5. Inspect the Breathing Circuit for Leaks or Incorrect Setup
Check all accessible circuit connections, humidification components, filters, valves, and accessories for leaks, disconnections, or improper assembly.
Expected outcome: The breathing system is intact and correctly configured. If correcting a leak restores expected oxygen measurement, troubleshooting can stop after verification.
6. Verify Ventilator Settings and Configuration
Confirm that the commanded oxygen setting and relevant ventilation configuration match what is expected for the test being performed.
Avoid unauthorized configuration changes. Compare with an established known-good setup if needed.
Expected outcome: The expected delivered oxygen concentration and configured value are understood and consistent.
7. Repeat Approved Oxygen Calibration
With the ventilator removed from clinical service and external conditions verified, repeat the normal approved oxygen calibration process.
Do not bypass unsuccessful calibration or alter service-level calibration values without appropriate authorization and documentation.
Expected outcome: Calibration completes normally. If it succeeds, proceed to independent functional verification.
8. Verify Oxygen Delivery Independently
Using approved calibrated test equipment, compare delivered oxygen concentration under an appropriate test setup.
Expected outcome: Delivered oxygen is consistent with the ventilator setting within the acceptance criteria specified by the appropriate manufacturer or facility procedure. Troubleshooting can stop when verification passes.
9. Compare External Components and Gas Sources
If readings remain questionable, repeat testing with verified gas sources and known-good external hoses or breathing-system components where appropriate.
Expected outcome: External gas delivery and removable components are definitively ruled in or out.
10. Escalate Persistent Oxygen Measurement Problems
If calibration continues to fail or independent testing shows unreliable oxygen delivery after external causes are eliminated, stop external troubleshooting.
Expected outcome: The ventilator remains unavailable for clinical use pending qualified evaluation.
If the Problem Persists
External gas supply, hoses, circuit configuration, leaks, and normal calibration have been evaluated. Remaining causes may involve internal oxygen sensing, gas-mixing, pneumatic, electronic, calibration, or software-related systems.
The ventilator 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 configured only by qualified personnel
Return-to-service testing should include oxygen concentration verification across appropriate operating conditions in addition to required ventilator checks. Knowing when oxygen delivery cannot be trusted and stopping troubleshooting is proper troubleshooting.
Clinical Use Tip
If delivered FiO2 is questionable, move the patient to a verified ventilator rather than relying solely on the affected ventilator's displayed oxygen value.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Respiratory Therapy reported that the Evita V600 displayed an oxygen concentration inconsistent with the selected setting."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found the oxygen supply hose was not fully connected at the wall source."
Resolution
What action was taken.
Example:
"The oxygen connection was secured, oxygen calibration completed successfully, and delivered FiO2 was verified with approved test equipment before return to service."
Helpful Details to Include (If Known)
- Exact oxygen-related message
- Selected FiO2
- Displayed FiO2
- Independent analyzer result
- Air and oxygen connections
- Gas outlet or source tested
- Hose condition
- Circuit leak findings
- Calibration result
- Results before and after correction
- Final device status
Final Thought
Questionable oxygen delivery requires immediate patient protection followed by systematic verification of gas supply, connections, circuit integrity, settings, and calibration. Internal failure should only be considered after these external causes are excluded and independent testing confirms the problem.
That is successful troubleshooting.