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What This Guide Helps With
This guide addresses situations where a Puritan Bennett 980 ventilator displays flow sensor errors, inaccurate tidal volumes, volume mismatch alarms, or inconsistent measured values.
The focus is on common, external, and easily verifiable causes—such as sensor setup, circuit configuration, moisture buildup, and calibration—before assuming internal sensor or board failure.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
- Move the patient to another ventilator if needed.
- Do not troubleshoot flow sensor issues while actively ventilating a patient unless clinically cleared.
- Flow measurement errors can directly affect delivered volumes.
2. Verify the Correct Circuit Is Installed
- Confirm adult vs. pediatric circuit matches ventilator configuration.
- Confirm the circuit type selected in the ventilator settings matches the physical circuit.
- Incorrect circuit selection can result in inaccurate volume calculations and flow sensor alarms.
3. Inspect the Flow Sensor Placement
- Confirm the proximal flow sensor is installed in the correct orientation.
- Ensure arrows (if present) align with flow direction.
- Verify it is securely seated and fully connected.
- Loose or reversed sensors commonly cause flow sensor errors.
4. Check for Moisture or Condensation
- Inspect the flow sensor for visible moisture.
- Check the circuit for water accumulation.
- Drain water traps if present.
- Replace the flow sensor if contaminated.
- Moisture alters flow measurement and is one of the most common causes of inaccurate volumes.
5. Inspect the Patient Circuit for Leaks
- Check all connections (wye, humidifier, filters, HME, expiratory limb).
- Inspect for cracked tubing or loose fittings.
- Confirm the exhalation valve assembly is properly seated.
- Leaks can cause volume discrepancies and false flow alarms.
6. Perform a System Check / Calibration
- Remove the patient from the circuit.
- Perform a full ventilator self-test or extended system check.
- Ensure calibration completes without error.
- This allows the ventilator to recalibrate internal flow measurement baselines.
7. Replace the Flow Sensor
- If errors persist, install a new, known-good flow sensor.
- Re-run system check.
- Disposable sensors are consumables and can drift or fail over time.
8. Evaluate Alarm Behavior
- Document exact alarm message.
- Document intermittent vs. constant behavior.
- Document whether measured tidal volume matches set volume.
- Document any trending discrepancies.
- Consistent error after external checks may indicate internal sensing hardware or signal processing issues.
If the Problem Persists
If circuit is verified correct, no moisture present, no leaks detected, sensor replaced, and calibration fails or alarms persist, the issue is likely internal (flow module, sensor interface board, or internal pneumatic fault).
- Remove the ventilator from service.
- Label it Out of Service.
- Send for bench evaluation or depot repair.
Knowing when to stop prevents unsafe ventilation and protects patient safety.
Clinical Use Tip
Flow accuracy directly affects delivered tidal volume and minute ventilation.
Never troubleshoot flow sensor errors on an actively ventilated patient unless they are safely transitioned to backup ventilation first.
Even small inaccuracies can be clinically significant in neonatal or low tidal volume cases.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
“Ventilator displaying ‘Flow Sensor Error’ and reported tidal volumes lower than set volume during use in ICU.”
Cause
What was observed during troubleshooting.
Example:
“Moisture observed inside proximal flow sensor. System check initially failed calibration. Sensor replaced and circuit drained.”
Resolution
What action was taken.
Example:
“Replaced proximal flow sensor, drained condensation from circuit, performed full system check. Calibration passed and volume readings returned to normal. Ventilator returned to service.”
Helpful Details to Include
- Circuit type verified
- Moisture present (yes/no)
- Sensor replaced (yes/no)
- Leak test result
- Calibration pass/fail
- Alarm text
- Final operational status
Final Thought
Accurate flow measurement is critical to safe ventilation. Always rule out simple causes—circuit setup, moisture, leaks, and sensor condition—before assuming internal failure. Logical troubleshooting and proper escalation protect both the patient and the integrity of the equipment.
That is successful troubleshooting.