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What This Guide Helps With
Troubleshoots oxygen calibration or FiO2 accuracy problems caused by gas supply, connections, circuit setup, sensor conditions, leaks, or service-level faults.
Step-by-Step Troubleshooting
1. Protect the Patient and Maintain Verified Oxygen Delivery
Do not continue using a ventilator for patient care when delivered oxygen concentration is questionable.
Transfer the patient to another verified ventilator or alternate oxygen-delivery method and independently monitor oxygenation as clinically appropriate.
Expected outcome: Patient ventilation and oxygen delivery are maintained by verified equipment.
2. Confirm the Exact Failure
Determine whether the problem is:
- Oxygen calibration will not complete
- Calibration passes but measured FiO2 is inaccurate
- FiO2 drifts
- Oxygen concentration is unstable
- The problem occurs only with one gas source or circuit
Use approved oxygen-analysis equipment when verifying delivered concentration.
Expected outcome: The failure is reproduced under controlled conditions.
3. Verify Oxygen Supply Connection
Inspect the oxygen supply path from the wall source or cylinder to the ventilator.
Check:
- Hose connection
- Hose damage
- Correct gas connection
- Kinks
- Quick-connect engagement
- Supply availability
- Cylinder valve and contents when applicable
Expected outcome: A reliable oxygen source is correctly connected and available.
4. Verify Air Supply When Applicable
Because delivered FiO2 depends on gas blending, inspect the air supply and its associated hose and connection when the ventilator setup uses an external air source.
Expected outcome: Both required gas supplies are correctly connected and available.
5. Inspect the Breathing Circuit
Check the external circuit for:
- Major leaks
- Loose fittings
- Incorrect assembly
- Open accessory ports
- Incorrect test lung connection
- Water accumulation
- Incompatible external accessories
Expected outcome: The breathing circuit is correctly assembled and leak-free enough for valid testing.
6. Repeat the Approved Oxygen Calibration
Perform the approved oxygen calibration or pre-use procedure under the required conditions.
Do not manipulate undocumented calibration constants or hidden service parameters.
Expected outcome: Calibration completes normally. If subsequent FiO2 verification passes, troubleshooting can stop.
7. Independently Verify Delivered FiO2
Use an approved, appropriately maintained oxygen analyzer at the appropriate test location.
Test more than one normal operating point if required by facility or manufacturer procedures.
Expected outcome: Measured oxygen concentration agrees with the ventilator setting within the applicable approved acceptance criteria.
8. Compare Gas Source or Hose When Practical
If results remain abnormal, test with a known-good compatible gas hose or alternate verified gas source where safely available.
Change one variable at a time.
Expected outcome: If the problem follows the hose or supply source, the external cause is identified and the ventilator does not require internal repair.
9. Complete Final Ventilator Verification
Perform all required gas-delivery, alarm, pre-use, and performance testing before return to service.
Expected outcome: Oxygen calibration succeeds and delivered FiO2 passes approved verification. Troubleshooting can stop.
If the Problem Persists
Gas supplies, hoses, circuit setup, calibration procedure, and independent FiO2 measurement have been verified. A persistent failure may involve the oxygen measurement system, gas-blending system, internal pneumatic path, valves, sensors, or related service-level components.
The Servo-n should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated with appropriate Getinge service documentation and approved gas-analysis equipment
- Repaired or calibrated only by qualified personnel
Do not return the ventilator to service until delivered oxygen concentration meets approved performance requirements.
Knowing when to stop external troubleshooting and escalate is proper troubleshooting.
Clinical Use Tip
When FiO2 accuracy is questioned, use an independently verified oxygen analyzer rather than relying only on the ventilator's displayed value.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Respiratory Therapy reported that the Servo-n failed oxygen calibration and delivered oxygen measured lower than expected."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found the oxygen supply hose was not fully engaged at the wall connection."
Resolution
What action was taken.
Example:
"The oxygen hose was securely reconnected, oxygen calibration completed, delivered FiO2 passed independent verification, and the ventilator was returned to service."
Helpful Details to Include (If Known)
- Exact calibration failure
- Oxygen and air source used
- Hose and connector condition
- Circuit configuration
- Leak findings
- Independent oxygen analyzer result
- Result after alternate gas source or hose
- Pre-use check result
- Final FiO2 verification
- Final device status
Final Thought
Oxygen-delivery faults require immediate patient protection and independent verification. Check gas sources, hoses, circuit setup, and calibration conditions before assuming an internal blender or sensor failure, then escalate when performance remains outside approved criteria.
That is successful troubleshooting.