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What This Guide Helps With
Troubleshooting failed pre-use or breathing-system leak tests caused by circuit setup, loose connections, open valves, accessories, seals, or test preparation.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not troubleshoot a failed pre-use check or leak test while the WATO EX Series is supporting an active patient.
If the failure is discovered during clinical use:
- Notify the anesthesia provider immediately.
- Confirm ventilation, oxygen delivery, airway pressure, and gas monitoring using approved independent methods.
- Move the patient to another verified anesthesia machine or approved ventilation method if reliable operation cannot be confirmed.
- Follow the facility’s anesthesia-equipment failure procedure.
Expected outcome: Patient care is no longer dependent on an anesthesia machine that has not successfully completed its required checks.
Continue troubleshooting only after the machine has been removed from active patient use.
2. Record the Exact Failed Check
Review the displayed test result and determine whether the failure involves:
- Complete pre-use or system check
- Breathing-system leak test
- Circuit compliance test
- Manual circuit leak test
- Ventilator check
- Gas-supply check
- Flow-sensor check
- Another specifically identified component
Record the complete message, test stage, and any displayed corrective guidance. Mindray anesthesia systems identify failed automatic or manual circuit leak tests through their system-check functions.
Expected outcome: The failed portion of the checkout is identified rather than treating every pre-use failure as the same problem.
3. Confirm Adequate Gas and Electrical Supplies
Verify:
- The power cord is fully seated.
- The wall outlet is functional.
- Required pipeline gas hoses are correctly connected.
- Pipeline pressure indicators are within the facility’s expected range.
- Backup cylinders are installed and adequately filled when required by facility procedure.
- No supply hose is kinked, damaged, or connected to the wrong gas source.
Correct any external supply issue and repeat the check.
Expected outcome: The machine has stable power and adequate gas supplies throughout the test.
If the check passes, return the machine to service only after completing the entire required pre-use checkout, then stop.
4. Restore the Machine to the Required Test Configuration
Follow the on-screen test instructions and verify that the machine is configured exactly as requested.
Check that:
- The correct ventilation mode or operating state is selected.
- The bag/ventilator selector is in the position requested by the test.
- The adjustable pressure-limiting valve is set as directed.
- The fresh-gas controls are positioned as instructed.
- The oxygen flush is not being pressed.
- The Y-piece is open or occluded at the test port as directed.
- A test lung is installed only when requested.
Do not assume that the same setup applies to every software version or every WATO EX model.
Expected outcome: The test is performed under the conditions expected by the anesthesia system.
5. Inspect the Patient Breathing Circuit
Examine the complete breathing circuit from the inspiratory and expiratory ports to the Y-piece.
Look for:
- Loose circuit connections
- Cracked or punctured tubing
- Split cuffs
- Missing adapters
- Open sampling ports
- Uncapped auxiliary connections
- Loose elbows or filters
- Incorrectly assembled expandable tubing
- Water accumulation or severe circuit obstruction
Reconnect all fittings firmly. Replace questionable disposable tubing, filters, adapters, or test lungs with verified compatible components.
Expected outcome: The external patient circuit is complete, unobstructed, and capable of holding pressure.
Repeat the test. If it passes, document the defective or loose circuit component and stop.
6. Isolate Optional Accessories
Temporarily remove nonessential external accessories that may introduce leakage, including:
- Gas-sampling lines
- Spirometry adapters
- Humidification components
- Extra elbows or extensions
- Nebulizer adapters
- Auxiliary monitoring connections
- Specialty breathing-circuit accessories
Cap or reconnect each port correctly before repeating the test.
Reinstall accessories individually after a successful test to identify the leaking component.
Expected outcome: An accessory-related leak is either identified or ruled out.
7. Check the Y-Piece Test Seal
When the system instructs the operator to occlude the Y-piece:
- Confirm the Y-piece is fully seated on the designated leak-test port or approved occlusion device.
- Verify the seal is tight.
- Inspect the test port or plug for damage, contamination, or a missing seal.
- Do not occlude the circuit by hand unless the applicable operating procedure specifically permits it.
Expected outcome: The patient connection is completely sealed during the pressure-holding portion of the test.
Repeat the check. If it passes, the previous failure was caused by inadequate Y-piece occlusion.
8. Inspect the Breathing-System Assembly
Without performing internal disassembly, visually confirm that accessible breathing-system components are properly installed.
Check:
- Inspiratory and expiratory valve assemblies are seated.
- Valve covers are secured.
- The absorber or breathing-system assembly is fully latched.
- The carbon-dioxide absorbent canister is correctly installed.
- Reusable breathing-system components are aligned and locked.
- Drain plugs, water collectors, and accessible covers are closed.
- No visible gasket or seal is displaced, pinched, contaminated, or missing.
A canister, valve cover, or breathing-system component that appears installed but is not fully seated can create a significant leak.
Expected outcome: All user-accessible breathing-system components are properly assembled and sealed.
9. Check the Carbon-Dioxide Absorbent Canister
Inspect the absorbent canister for:
- Incomplete engagement
- A loose locking mechanism
- A cracked housing
- A damaged sealing surface
- Material trapped across the sealing edge
- Incorrect assembly after absorbent replacement
- A bypass mechanism that is not fully returned to its operating position, when equipped
Remove and reinstall the canister only according to the approved operator procedure.
Expected outcome: The absorbent assembly forms a complete seal with the breathing system.
Repeat the leak test. If it passes, stop and document the canister installation issue.
10. Inspect the Manual Breathing Bag and Bag Arm
Verify that:
- The breathing bag is securely attached.
- The bag neck is not torn or stretched.
- The bag has no punctures.
- The bag-arm connection is tight.
- The bag-arm assembly is not visibly cracked or loose.
- Any selectable bag position or connection is correctly configured.
Replace the breathing bag with a verified compatible bag when its condition is questionable.
Expected outcome: The manual ventilation pathway can hold pressure without leakage.
11. Inspect the Vaporizer Installation
Confirm that each installed vaporizer:
- Is fully seated on its mounting manifold.
- Is locked in position.
- Is in the required setting for the checkout.
- Has its filler cap closed securely.
- Shows no evidence of liquid anesthetic leakage.
- Has no visibly damaged mounting or sealing surface.
Do not operate or test a vaporizer that has visible agent leakage. Mindray instructs users to ensure vaporizer connections are leak-tight and not to use a vaporizer when anesthetic-agent leakage is present.
When permitted by facility policy, remove a questionable vaporizer using the approved operator procedure and repeat the check.
Expected outcome: The vaporizer and mounting manifold are ruled in or out as the source of the leak.
12. Check Flow Sensors and Accessible Sensor Connections
Inspect user-removable flow sensors and their connections for:
- Incorrect orientation
- Incomplete insertion
- Loose electrical connections
- Moisture
- Debris or contamination
- Cracks or physical damage
- Missing or damaged accessible seals
Allow wet components to dry or replace them according to facility and manufacturer procedures. Do not insert tools or compressed air into sensor elements.
Expected outcome: Flow sensors are installed correctly and are suitable for the system check.
13. Repeat the Complete Pre-Use Check
After correcting all identified external issues:
- Restore the machine to its normal configuration.
- Install the intended patient circuit and required accessories.
- Follow each displayed instruction exactly.
- Run the complete pre-use or system checkout, not only the previously failed portion.
- Verify that every required test passes.
Mindray provides automatic checking functions intended to verify multiple anesthesia-system components and display corrective guidance when a check fails.
Expected outcome: The WATO EX Series completes its required checkout without unresolved failures.
Do not return the machine to clinical service based solely on an isolated test passing if the complete pre-use check remains unsuccessful.
If the Problem Persists
If the pre-use check or leak test continues to fail after the circuit, accessories, breathing-system assembly, canister, bag, vaporizers, supplies, sensors, and required test configuration have been verified, common external causes have been ruled out.
The remaining problem may involve an internal valve, manifold, pressure-control component, pneumatic pathway, sensor, ventilator assembly, or internal seal.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for qualified repair or bench evaluation
- Evaluated using the correct Mindray service documentation for the exact WATO EX model and software revision
Do not bypass a failed checkout, suppress the result, or return the machine to service because ventilation appears normal during a brief functional test. Knowing when to stop and escalate is proper troubleshooting.
Clinical Use Tip
Never troubleshoot a failed anesthesia-machine leak test on an active patient. Move the patient to another verified machine first and perform testing only under safe, controlled conditions.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Anesthesia staff reported that the Mindray WATO EX Series failed the pre-use breathing-system leak test before the scheduled procedure."
Cause
What was observed during troubleshooting.
Example:
"Inspection found the carbon-dioxide absorbent canister incompletely latched, allowing the breathing system to lose pressure during the automatic leak test."
Resolution
What action was taken.
Example:
"Removed and correctly reinstalled the absorbent canister, inspected the patient circuit and accessories, and completed the full pre-use checkout successfully."
Helpful Details to Include (If Known)
- Exact failed check or displayed message
- Whether the automatic or manual test failed
- Test stage at which the failure occurred
- Pipeline pressures verified
- Backup cylinder status
- Outlet and AC-power status
- Circuit type and configuration
- Circuit or breathing bag exchanged
- Y-piece test-port seal verified
- Absorbent canister installation checked
- Vaporizer installation checked
- Flow-sensor condition
- Accessories removed or exchanged
- Whether the failure followed cleaning or reassembly
- Alarm behavior and indicator lights
- Unusual sounds
- Unusual heat or anesthetic-agent odor
- Complete checkout result after correction
- Final device status
Final Thought
A failed pre-use or leak test must be treated as a patient-safety issue. Check external configuration and sealing points logically, repeat the complete checkout, and escalate when the machine cannot demonstrate reliable operation. Accurate CCR documentation preserves what was reported, what was found, and why the device was returned to service or removed for repair.
That is successful troubleshooting.