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What This Guide Helps With
Addresses oxygen calibration failures or incorrect displayed/delivered FiO2 associated with gas supply, connections, settings, circuit conditions, or sensing problems.
Step-by-Step Troubleshooting
1. Protect the Patient and Verify Oxygenation Independently
If oxygen delivery or FiO2 accuracy is questionable during patient use, immediately provide ventilation and oxygen using another verified device or appropriate backup method. Do not continue relying on uncertain oxygen delivery while troubleshooting.
Expected outcome: The patient receives dependable ventilation and oxygenation independent of the suspect Evita V800.
2. Confirm the Exact Reported Condition
Determine whether the issue is:
- O2 calibration failure
- Displayed FiO2 differing from expected
- Delivered FiO2 differing from an independent analyzer
- An intermittent oxygen-related alarm
- A problem only at certain settings
Record the displayed message and ventilator conditions.
Expected outcome: The exact oxygen-related problem is reproducible or clearly characterized. If the discrepancy cannot be reproduced, complete appropriate verification before return to service.
3. Verify Oxygen and Air Supply Connections
Inspect both gas hoses and wall-source connections. Confirm oxygen is connected to the oxygen inlet and air to the air inlet. Check for loose fittings, damage, crossed hoses, kinks, or obvious leakage.
Expected outcome: Both gas supplies are correctly connected and available. If correcting a gas connection restores normal calibration or FiO2, complete verification and troubleshooting can stop.
4. Verify Facility Gas Availability
Confirm the required source gases are available from the facility outlets. If the source is questionable, compare with a known-good outlet or approved source according to facility procedures.
A ventilator cannot provide expected oxygen blending when the necessary source gas is unavailable or unstable.
Expected outcome: Gas availability is confirmed independently. If a facility gas problem is identified, remove the ventilator from that source and coordinate correction of the infrastructure issue.
5. Check Ventilator Oxygen Settings
Verify the requested oxygen concentration and other relevant user-accessible settings are appropriate. Confirm the reported discrepancy is not the result of an unintended setting change.
Do not alter protected calibration or service parameters.
Expected outcome: The commanded oxygen setting is understood and appropriate. If correcting an unintended user-accessible setting resolves the discrepancy, verify delivered oxygen and troubleshooting can stop.
6. Inspect the Breathing Circuit
Check for major leaks, disconnected components, open ports, incorrect accessory placement, or unusual circuit setup that could affect independent oxygen measurements.
If an external analyzer is being used, verify its sampling point and setup are appropriate.
Expected outcome: The respiratory circuit and test setup are suitable for comparing commanded and measured oxygen. If correcting the setup restores expected readings, troubleshooting can stop after verification.
7. Repeat the Approved Oxygen Calibration or System Check
With the ventilator off the patient and external causes corrected, repeat the applicable user-accessible O2 calibration or system check according to approved procedures.
Expected outcome: Calibration completes successfully without unresolved oxygen-related messages. If successful, proceed to independent functional verification.
8. Verify FiO2 With Approved Test Equipment
When required by facility procedure, connect an appropriate calibrated oxygen analyzer or ventilator tester and compare delivered oxygen with the selected ventilator setting across a representative functional check.
Do not invent or apply undocumented tolerance limits.
Expected outcome: Oxygen delivery is consistent with approved manufacturer or facility acceptance criteria. If it passes, troubleshooting can stop and the ventilator may be returned to service.
9. Compare External Components or Supplies
If the discrepancy persists, use known-good compatible hoses, circuit components, or gas outlets as appropriate to eliminate external variables one at a time.
Expected outcome: External supply and accessory causes are either identified or ruled out. If a known-good substitution corrects the problem, replace or remove the faulty external item and complete final verification.
10. Escalate Unresolved Oxygen Problems
If oxygen calibration continues to fail or delivered FiO2 cannot be verified within applicable acceptance criteria after external causes have been eliminated, stop troubleshooting.
Expected outcome: The ventilator remains removed from service until qualified repair and performance verification are completed.
If the Problem Persists
A persistent oxygen calibration or FiO2 accuracy problem after gas supplies, hoses, settings, circuit configuration, and independent measurement setup have been verified may indicate an internal oxygen sensing, gas-blending, pneumatic, calibration, electronic, or service-level problem.
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
After service, verify oxygen calibration and delivered concentration using approved test equipment before return to patient use. Knowing when measured oxygen delivery cannot be trusted and removing the ventilator from service is proper troubleshooting.
Clinical Use Tip
When FiO2 accuracy is questioned, maintain patient oxygenation with a verified alternative and independently verify the ventilator before reuse.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Respiratory Therapy reported the Evita V800 displayed an oxygen-delivery discrepancy during pre-use testing."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found the oxygen supply hose was not fully connected at the wall outlet, resulting in an unstable gas supply."
Resolution
What action was taken.
Example:
"Clinical Engineering secured the oxygen connection, repeated the oxygen-related system check, verified delivered FiO2 with approved test equipment, and returned the ventilator to service."
Helpful Details to Include (If Known)
- Exact O2-related message
- Commanded FiO2
- Independently measured FiO2
- Air supply status
- Oxygen supply status
- Hose and outlet condition
- Circuit setup
- Analyzer or tester used
- Calibration result
- Results before and after correction
- Final device status
Final Thought
Uncertain oxygen delivery is a patient-safety issue. Verify source gases, connections, settings, circuit conditions, and independent measurement before assuming an internal failure, and remove the ventilator from service whenever oxygen performance cannot be verified.
That is successful troubleshooting.