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What This Guide Helps With
Helps isolate expiratory cassette test failures caused by incorrect installation, moisture, contamination, damage, cleaning-related issues, or cassette compatibility.
Step-by-Step Troubleshooting
1. Protect the Patient and Remove the Ventilator From Dependent Use
Do not troubleshoot a failed expiratory cassette test while a patient depends on the ventilator.
Provide alternate verified ventilatory support as clinically appropriate and remove the affected Servo-u from patient use until the expiratory system passes required testing.
Expected outcome: The patient is supported by a reliable device and the Servo-u can be evaluated safely.
2. Confirm the Exact Test Failure
Repeat only the normal user-accessible pre-use or system test appropriate to the expiratory cassette and note where the failure occurs.
Determine whether the problem began:
- Immediately after cleaning
- After sterilization or disinfection
- After cassette replacement
- After reinstalling the same cassette
- After prolonged storage
- Without any recent cassette handling
Do not repeatedly force the ventilator through failed testing if the same condition is consistently reproduced.
Expected outcome: The failure is confirmed and its relationship to cassette handling is known.
3. Verify the Cassette Is Fully Installed
Remove and reinstall the expiratory cassette using normal approved handling procedures.
Inspect that it:
- Is oriented correctly
- Seats completely
- Locks or latches normally
- Is not obstructed by tubing, packaging, or other material
- Has no visibly displaced external seals or components
Do not force the cassette into position.
Expected outcome: The cassette installs smoothly and is fully seated.
If correct installation allows the cassette test to pass, complete the remaining ventilator verification and stop troubleshooting.
4. Inspect for Residual Moisture
A cassette recently cleaned or processed may retain moisture that affects testing.
Inspect accessible areas for visible water droplets, condensation, or retained cleaning fluid. Allow the cassette to dry according to the approved cleaning and reprocessing process.
Do not use unapproved heat, compressed air, or drying methods.
Expected outcome: The cassette is visibly dry and ready for testing according to approved processing requirements.
If proper drying resolves the test failure, complete the full pre-use check and stop troubleshooting.
5. Inspect for Contamination or Cleaning Residue
Check accessible cassette surfaces and interfaces for:
- Cleaning residue
- Dried deposits
- Lint
- Foreign material
- Contamination around accessible flow paths or connection surfaces
Do not insert tools into protected sensing areas or attempt internal disassembly.
If contamination is present, have the cassette reprocessed according to the approved cleaning procedure.
Expected outcome: Accessible cassette surfaces and interfaces are clean and free of residue.
If proper reprocessing restores successful testing, complete functional verification and stop troubleshooting.
6. Inspect the Cassette for Physical Damage
Examine the cassette for:
- Cracks
- Warping
- Damaged connection surfaces
- Broken locking features
- Loose external components
- Evidence of impact or improper handling
A damaged expiratory cassette should not be returned to clinical service.
Expected outcome: The cassette is physically intact with no visible damage affecting fit or function.
If damage is found, remove the cassette from service and test the ventilator with a known-good compatible cassette.
7. Verify Cassette Compatibility
Confirm that the installed expiratory cassette is the appropriate compatible component for the Servo-u and has not been mixed with a cassette intended for another platform or configuration.
Avoid assuming similar appearance means compatibility.
Expected outcome: The cassette is confirmed to be appropriate for the Servo-u configuration being tested.
If an incorrect cassette was installed, replace it with the correct compatible cassette and repeat the required test.
8. Test With a Known-Good Compatible Cassette
Install a known-good compatible cassette that has been properly cleaned, processed, dried, and previously demonstrated normal operation.
Repeat the appropriate ventilator test.
Expected outcome: The ventilator successfully tests with the known-good cassette.
If the known-good cassette passes, remove the original cassette from service for further evaluation or replacement. Troubleshooting can stop after complete ventilator verification.
If the known-good cassette also fails, continue.
9. Inspect the Ventilator Cassette Interface
With the ventilator safely removed from patient use, inspect the accessible cassette receiving area for:
- Foreign material
- Fluid
- Damaged external contact surfaces
- Obstructions
- Evidence that the cassette cannot fully engage
Do not disassemble the ventilator or manipulate internal sensors or valves.
Expected outcome: The cassette interface is clean, dry, unobstructed, and visibly intact.
If an external obstruction is safely removed and the cassette test passes afterward, complete the full pre-use verification and stop troubleshooting.
10. Perform Final Functional Verification
After resolving the problem, complete the required Servo-u pre-use and functional verification appropriate to the repair.
Confirm:
- Expiratory cassette test passes
- Cassette remains securely installed
- Ventilation operates normally with an approved test setup
- No unexpected leakage or alarm behavior is present
- Other required pre-use checks pass
Expected outcome: The expiratory system performs normally and the ventilator is suitable for return to service.
11. Escalate Repeated Cassette Test Failures
If multiple known-good compatible cassettes fail despite correct installation and a clean, dry interface, stop external troubleshooting.
The ventilator should not be used clinically until the cause is evaluated by qualified service personnel.
Expected outcome: The device is properly removed from service for further evaluation.
If the Problem Persists
Common external causes such as installation, residual moisture, contamination, physical damage, processing issues, and cassette compatibility have been ruled out.
The remaining failure may involve the ventilator's expiratory cassette interface, sensing system, internal pneumatic components, protected calibration, or other service-level conditions.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using appropriate Getinge service documentation and approved test equipment
- Repaired or configured only by qualified personnel
Successful repair must be followed by the required pre-use testing and appropriate ventilator performance verification before return to patient care.
Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
Never bypass a failed expiratory cassette test; move the patient to verified ventilatory support until the Servo-u passes all required pre-use checks.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Respiratory Therapy reported that the Servo-u failed the expiratory cassette test after the cassette was cleaned and reinstalled."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found visible residual moisture in the recently processed expiratory cassette."
Resolution
What action was taken.
Example:
"Removed the wet cassette, allowed it to complete approved drying, reinstalled it, verified the cassette test and full pre-use check passed, and returned the ventilator to service."
Helpful Details to Include (If Known)
- When the cassette was last cleaned or processed
- Whether the failure began immediately after cleaning
- Cassette installation condition
- Presence of moisture or residue
- Visible physical damage
- Cassette compatibility
- Result with a known-good cassette
- Condition of the ventilator cassette interface
- Exact pre-use test result
- Results before and after correction
- Final device status
Final Thought
A failed cassette test should be approached from the outside in: verify processing, dryness, installation, compatibility, and the cassette itself before suspecting the ventilator. Protect the patient, verify the correction completely, escalate persistent failures, and document what was actually found.
That is successful troubleshooting.