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What This Guide Helps With
Oxygen calibration or FiO2 measurement problems caused by gas supply, sampling conditions, sensor installation, moisture, accessories, or calibration conditions.
Step-by-Step Troubleshooting
1. Protect the Patient and Verify Oxygen Independently
Do not troubleshoot unreliable oxygen measurement while a patient depends on the affected machine. Maintain anesthesia and oxygen delivery with another verified system.
If clinical oxygen concentration is in doubt, use an appropriate independent verified measurement method.
Expected outcome: Patient oxygen delivery is maintained independently of the questionable measurement.
2. Confirm the Reported O2 Problem
Record whether the complaint is calibration failure, unstable FiO2, implausible FiO2, delayed response, or disagreement with another verified measurement.
Repeat the condition under controlled bench conditions when safe.
Expected outcome: The oxygen-measurement problem is confirmed and characterized.
3. Verify Oxygen Supply
Confirm the O2 pipeline connection is correct, fully seated, undamaged, and connected to the appropriate wall outlet. Verify the available backup cylinder condition when relevant.
A supply issue should be ruled out before assuming a sensor failure.
Expected outcome: A stable oxygen source is available to the machine.
4. Inspect Gas Sampling Components
Check sampling lines, water traps, filters, connectors, and accessible gas-analysis components for disconnection, kinks, obstruction, moisture, contamination, or leaks.
Expected outcome: The gas-sampling pathway is intact and unobstructed.
5. Verify Sensor or Measurement Component Installation
Inspect externally removable oxygen-sensing components for proper installation, full seating, contamination, damage, or improper handling.
Do not access internal analyzer components or service-level assemblies.
Expected outcome: Externally serviceable sensing components are correctly installed.
6. Verify Calibration Conditions
Perform only the normal approved calibration procedure and confirm the machine is exposed to the appropriate conditions required by that procedure.
Avoid calibrating while the sampling path is unstable or contaminated.
Expected outcome: Calibration completes successfully under appropriate external conditions. If successful and FiO2 readings normalize, troubleshooting can stop after verification.
7. Compare With an Independent Analyzer
When available, use a calibrated independent oxygen analyzer during bench testing to compare the machine's displayed FiO2 with an external reference.
Do not adjust service calibration merely to force agreement.
Expected outcome: The displayed oxygen concentration responds appropriately and agrees sufficiently for the applicable return-to-service procedure.
8. Substitute External Sampling Components if Appropriate
Replace suspect disposable sampling lines, water traps, filters, or other removable accessories with known-good compatible items and repeat the measurement check.
Expected outcome: Normal oxygen measurement returns after substitution, confirming an external accessory cause.
9. Perform Final Verification
Verify successful calibration, stable oxygen measurement, appropriate response to controlled changes in delivered oxygen during testing, and related alarm operation.
Expected outcome: FiO2 measurement is stable and reliable with no recurring calibration failure.
10. Escalate Persistent O2 Measurement Problems
If calibration still fails or FiO2 remains unreliable after supply, sampling pathway, accessories, and external sensing components are verified, remove the machine from service.
Expected outcome: Further diagnosis is transferred to qualified service personnel.
If the Problem Persists
External oxygen-supply, sampling, accessory, and calibration-condition problems have been ruled out. The remaining issue may involve an internal gas-analysis module, sensor interface, pneumatic sampling system, signal-processing pathway, or service-level calibration.
Remove the machine from service, label it Out of Service, and evaluate it using appropriate Drager service documentation and approved gas-analysis test equipment. Internal repair or calibration must be performed by qualified personnel.
Complete oxygen-measurement verification, system testing, ventilation checks, and alarm testing before return to service.
Knowing when to stop external troubleshooting and escalate is proper troubleshooting.
Clinical Use Tip
Anesthesia should not continue on a machine with unreliable FiO2 measurement unless an approved alternate monitoring method and clinical contingency are established.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"OR staff reported the Atlan A300 displayed unstable FiO2 values and would not complete oxygen calibration."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found moisture obstructing the external gas-sampling line."
Resolution
What action was taken.
Example:
"Replaced the affected sampling component, completed oxygen calibration successfully, compared FiO2 with a verified analyzer, and returned the machine to service."
Helpful Details to Include (If Known)
- Exact O2 calibration message
- Reported FiO2 behavior
- Pipeline and cylinder status
- Sampling-line condition
- Water-trap condition
- Sensor installation
- Independent analyzer comparison
- Known-good substitutions
- Results before and after correction
- Final calibration result
- Final device status
Final Thought
Reliable oxygen measurement is a patient-safety function, so confirm the gas source and sampling path first, verify performance independently, and escalate any unresolved measurement uncertainty.
That is successful troubleshooting.