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What This Guide Helps With
This guide addresses the “O2% low” alarm indicating the measured oxygen concentration is below the set value, which can result in inadequate oxygen delivery due to supply issues, sensor inaccuracies, or gas control problems.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
- Immediately assess patient oxygenation and ventilation status
- Use alternate ventilation (bag-valve mask or backup ventilator) if needed
- Do not continue troubleshooting on an unstable patient
2. Verify the Reported Alarm and Behavior
- Confirm the “O2% low” alarm is active
- Compare set FiO2 to measured FiO2
- Observe if the alarm is continuous or intermittent
- Check for unstable or fluctuating readings
3. Check Oxygen Supply Source (Most Common Cause)
- Confirm wall oxygen supply is connected
- Verify pressure is within normal range (~50 psi / ~3.5 bar)
- Inspect supply hose for kinks or disconnections
4. Inspect Gas Connections and Hoses
- Ensure O2 hose is securely connected at both ends
- Check for leaks, cracks, or loose fittings
- Swap with a known-good hose if available
5. Verify Ventilator Settings
- Confirm FiO2 setting is appropriate
- Check for recent setting changes
- Ensure alarm limits are correctly configured
6. Calibrate the Oxygen Sensor
- Perform oxygen sensor calibration per manufacturer procedure
- Observe if readings stabilize after calibration
7. Run Extended System Test (EST)
- Perform EST to evaluate internal gas delivery and sensor function
- Check for any oxygen-related failures
8. Isolate Sensor vs Device Issue
- Replace with a known-good oxygen sensor if available
- Recheck for alarm resolution
If the Problem Persists
If all external causes, calibration, and sensor replacement have been ruled out, internal oxygen control or measurement components may be failing.
- Remove the ventilator from service
- Label the device Out of Service
- Send for repair or bench evaluation
Clinical Use Tip
Never troubleshoot a ventilator with unresolved oxygen alarms while connected to a patient. Always transition the patient to a safe, reliable ventilation source first.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Ventilator alarming O2% low with measured oxygen below set FiO2 during patient use."
Cause
What was observed during troubleshooting.
Example:
"Low wall oxygen pressure and unstable sensor readings observed during calibration."
Resolution
What action was taken.
Example:
"Restored oxygen supply, calibrated sensor, and verified proper oxygen delivery. Replaced sensor if required."
Helpful Details to Include (If Known)
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
Low oxygen alarms are critical and should always be addressed immediately. Start with external supply and connections, verify sensor accuracy, and escalate when necessary to ensure safe patient care.
That is successful troubleshooting.