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What This Guide Helps With
This guide addresses situations where a Puritan Bennett 980 ventilator fails its pre-use check due to a circuit leak being detected. The focus is on common, external causes such as circuit assembly, humidifier setup, and accessory connections before assuming internal pneumatic failure. Most leak failures are related to setup, not internal defects.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- Confirm the ventilator is not connected to a patient.
- Ensure the ventilator is disconnected from the patient before performing any troubleshooting.
- Leak tests should only be performed with a test lung.
Verify Correct Circuit Type Selection
- Confirm that the selected circuit type in the ventilator settings matches the actual circuit installed (adult, pediatric, single limb vs dual limb).
- A mismatch can cause the ventilator to interpret normal compliance as a leak.
Inspect Circuit Assembly from Ventilator to Test Lung
- Check for loose connections at the inspiratory and expiratory ports.
- Check for partially seated tubing.
- Check for missing or cracked adapters.
- Check for improperly installed expiratory filters.
- Remove and firmly reseat each connection one at a time. Many leaks are caused by incomplete connections.
Check the Test Lung and Port Cap
- Ensure the test lung is intact (no tears or loose fittings).
- Ensure the patient wye is securely attached.
- Ensure any unused ports are capped.
- A cracked test lung or open sampling port will trigger a leak failure.
Inspect the Humidifier Setup (If Installed)
- If a humidifier is in line, confirm the chamber is properly seated.
- Check that water chamber seals are intact.
- Inspect for cracks in the chamber.
- Ensure temperature probe ports are capped if unused.
- Temporarily bypass the humidifier with a dry circuit if necessary to isolate the issue.
Examine the Expiratory Filter and Valve Area
- Ensure the expiratory filter is installed correctly.
- Ensure it is not cross-threaded.
- Ensure it is not damaged.
- Ensure it is fully tightened.
- A misaligned filter or debris at the seal can cause leak detection during self-test.
Check for Cracked or Worn Tubing
- Run your hand along the tubing and visually inspect for small splits near connectors.
- Inspect for stress cracks.
- Inspect for loose swivel joints.
- Swap with a known-good circuit if available to rule out disposable component failure.
Repeat Pre-Use Check After Corrections
- After reseating connections or replacing components, rerun the pre-use check.
- If the ventilator passes, return it to service.
If the Problem Persists
If a known-good circuit, test lung, filter, and proper configuration still result in a leak failure, common external causes have been ruled out.
The issue may involve:
- Internal pneumatic manifold leakage
- Expiratory valve assembly malfunction
- Internal pressure sensor drift
- Remove the ventilator from service.
- Label it Out of Service.
- Send it for bench evaluation or manufacturer-level repair.
Continuing repeated leak tests without identifying external causes is not effective troubleshooting. Knowing when to escalate protects patients and equipment.
Clinical Use Tip
Never attempt leak troubleshooting while the ventilator is supporting a patient. Transfer the patient to a confirmed functional ventilator before performing diagnostics. Leak failures can indicate compromised ventilation accuracy.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
“Ventilator failed pre-use check with ‘Circuit Leak Detected’ alarm in ICU prior to patient use.”
Cause
What was observed during troubleshooting.
Example:
“Loose connection identified at expiratory filter housing. Filter not fully seated, allowing leak during self-test.”
Resolution
What action was taken.
Example:
“Reseated expiratory filter, verified tight seal, reran pre-use check. Ventilator passed all tests and returned to service.”
Helpful Details to Include
- Circuit type selected
- Humidifier in use (yes/no)
- Test lung condition
- Expiratory filter condition
- Alarm wording exactly as displayed
- Whether a known-good circuit was tested
- Final device status (Passed pre-use / Sent to repair)
Final Thought
Most ventilator leak failures are setup-related. A calm, methodical approach—checking configuration, connections, and disposables first—prevents unnecessary downtime and avoids premature escalation. Patient safety always comes first, and proper documentation ensures traceability and accountability.
That is successful troubleshooting.