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What This Guide Helps With
Troubleshooting elevated airway pressure caused by circuit restrictions, patient-side accessories, valve problems, ventilator settings, or pressure-monitoring faults.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not perform extended troubleshooting while the WATO EX Series is supporting an active patient.
If a high airway pressure alarm occurs during clinical use:
- Notify the anesthesia provider immediately.
- Confirm ventilation using chest movement, capnography, oxygen saturation, airway-pressure waveforms, and available independent monitoring.
- Inspect for an immediately correctable kink, obstruction, or closed valve without delaying patient care.
- Provide manual ventilation or transfer the patient to another verified anesthesia machine when reliable ventilation cannot be confirmed.
- Follow the facility’s anesthesia-equipment failure procedure.
Expected outcome: Patient ventilation remains safely supported without depending on equipment with unresolved pressure behavior.
Continue troubleshooting only after the machine has been removed from active patient use.
2. Confirm the Exact Alarm Condition
Record:
- Complete alarm message
- Ventilation mode
- Set tidal volume or inspiratory pressure
- Set PEEP
- Pressure-limit setting
- Displayed peak and plateau pressures
- Whether the alarm occurs continuously or only during inspiration
- Whether the pressure waveform returns to baseline during expiration
The WATO EX Series monitors airway pressure and provides an adjustable high-pressure alarm limit; exact ranges and available ventilation settings vary by EX model.
Expected outcome: The alarm is confirmed as a reproducible airway-pressure condition rather than an isolated clinical event.
If the alarm cannot be reproduced and the system passes checkout, document the reported conditions and monitor the device according to facility policy.
3. Check the High-Pressure Alarm Limit
Verify that the airway high-pressure alarm limit is:
- Appropriate for the selected patient category
- Above the expected normal peak pressure
- Not accidentally set close to the current operating pressure
- Consistent with facility and anesthesia-provider requirements
Do not raise the alarm limit simply to silence a recurring alarm.
Expected outcome: The alarm limit is appropriately configured and not producing nuisance alarms during otherwise normal test ventilation.
If correcting the setting resolves the issue, complete a full checkout and stop.
4. Inspect the Patient Breathing Circuit
Examine the complete circuit from the machine to the patient connection for:
- Kinked or compressed tubing
- Tubing trapped beneath equipment
- Internally collapsed breathing hose
- Obstructed elbow or connector
- Incorrectly assembled circuit components
- Water accumulation
- Blocked filter or heat-and-moisture exchanger
- Closed or partially closed adjustable components
- Incompatible or damaged accessories
Replace questionable components with known-good, approved accessories.
Expected outcome: The breathing pathway is open, correctly assembled, and free of visible restrictions.
If replacing a restricted circuit component resolves the alarm, complete checkout and stop.
5. Remove Patient-Side Accessories
Disconnect nonessential patient-side accessories such as:
- Bacterial or viral filters
- Heat-and-moisture exchangers
- Sampling adapters
- Catheter mounts
- Flexible extensions
- Specialty connectors
Install a simple known-good test circuit and test lung.
Expected outcome: The machine ventilates the test lung without excessive peak pressure.
If the alarm clears, reconnect accessories individually to identify the restricted or incompatible component.
6. Check the Test Lung and Patient Connection
When bench testing:
- Use a known-good test lung with appropriate compliance.
- Confirm the test lung is not folded, compressed, or internally obstructed.
- Verify the patient connector and Y-piece are open.
- Confirm that no test plug or cap remains installed.
Expected outcome: The test load expands normally and the pressure waveform rises and falls predictably.
If a defective test lung or blocked connector caused the alarm, replace it and stop after successful checkout.
7. Inspect the Inspiratory and Expiratory Paths
With the machine removed from service, inspect accessible breathing-system components for:
- Incorrectly seated inspiratory or expiratory valves
- Moisture or contamination around valve assemblies
- Sticking or visibly damaged valve discs
- Misinstalled breathing-system components
- Loose, warped, cracked, or missing seals
- Foreign material restricting gas flow
Do not perform internal disassembly beyond procedures authorized by the facility and manufacturer.
Expected outcome: Accessible valves and breathing-system components are clean, dry, correctly installed, and move freely.
If correcting an installation problem resolves the alarm, perform the required checkout and leak test before returning the device to service.
8. Verify the APL Valve and Ventilation Mode
Confirm whether the alarm occurs in:
- Mechanical ventilation only
- Manual or spontaneous mode only
- Both operating modes
In manual mode, verify that the adjustable pressure-limiting valve:
- Is not set unnecessarily closed
- Rotates normally
- Releases pressure when adjusted
- Is not visibly obstructed or damaged
Expected outcome: Pressure can be controlled and released normally in manual mode.
A problem limited to manual mode may indicate an APL valve or manual breathing-path issue. A problem limited to mechanical ventilation may indicate a ventilator, expiratory-valve, or control problem.
9. Review Ventilator Settings
Verify that the selected settings are appropriate for the connected test lung:
- Tidal volume
- Inspiratory pressure
- PEEP
- Respiratory rate
- Inspiratory time
- I:E ratio
- Pressure limit
- Inspiratory pause
- Patient category
- Ventilation mode
Excessive tidal volume, inspiratory pressure, PEEP, or inspiratory time can produce elevated measured airway pressure.
Expected outcome: Test ventilation operates normally with controlled, appropriate settings.
If correcting an unintended setting resolves the alarm, complete checkout and stop.
10. Check for Incomplete Exhalation
Observe whether airway pressure returns to the selected PEEP level before the next breath.
Check for:
- Excessive respiratory rate
- Prolonged inspiratory time
- Inverse or inappropriate I:E ratio
- Restricted expiratory tubing
- Blocked expiratory filter
- Sticking expiratory valve
- Excessive scavenging restriction affecting the breathing system
Expected outcome: The test lung fully exhales and pressure returns to baseline between breaths.
If correcting the setting or expiratory restriction resolves the alarm, perform a complete operational checkout and stop.
11. Check the Scavenging Connection
Inspect the waste-gas scavenging system for:
- Kinked evacuation tubing
- Occluded scavenging hose
- Incorrect wall connection
- Restricted receiving system
- Improperly adjusted suction
- Full reservoir or obstructed interface
- Incorrectly assembled scavenging components
Temporarily test using the facility-approved configuration described in the applicable service documentation. Do not vent anesthetic gas into an occupied workspace.
Expected outcome: Scavenging operates without creating abnormal back pressure in the breathing system.
If the external scavenging system caused the alarm, correct the external condition and complete checkout.
12. Perform the System Checkout
After correcting external issues:
- Reassemble the breathing system correctly.
- Install a known-good circuit and test lung.
- Run the manufacturer-provided pre-use or system checkout.
- Perform the applicable leak and compliance tests.
- Test manual and mechanical ventilation.
- Verify pressure-limit operation.
- Confirm that peak pressure, PEEP, tidal volume, and waveforms are reasonable.
- Confirm that the high airway pressure alarm activates when intentionally challenged and clears when the restriction is removed.
Expected outcome: The machine passes checkout and delivers stable ventilation without unexpected high-pressure alarms.
If checkout passes and the alarm does not recur, document the repair and return the device according to facility policy.
If the Problem Persists
If the alarm continues with a known-good circuit, test lung, accessories, appropriate settings, unobstructed scavenging system, and correctly installed breathing-system components, common external causes have been ruled out.
The issue may involve:
- Inspiratory or expiratory valve malfunction
- Pressure-sensing tubing or transducer fault
- Expiratory flow-control malfunction
- Ventilator control fault
- Internal pneumatic restriction
- Internal breathing-system damage
- Calibration or control-system error
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for authorized repair or bench evaluation
Do not return the machine to clinical use based only on the alarm clearing after repeated restarts. Knowing when to stop and escalate is proper troubleshooting.
Clinical Use Tip
Never troubleshoot a recurring airway-pressure alarm on an active patient beyond immediate safety checks. Move the patient to another verified ventilation method before testing circuits, valves, settings, or internal functions.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Anesthesia staff reported repeated high airway pressure alarms during mechanical ventilation on the Mindray WATO EX Series."
Cause
What was observed during troubleshooting.
Example:
"Inspection found the expiratory breathing hose kinked behind the absorber assembly, restricting exhalation and causing pressure to remain elevated."
Resolution
What action was taken.
Example:
"Repositioned and replaced the affected hose, completed the system checkout, and verified stable pressure and normal alarm operation using a test lung."
Helpful Details to Include (If Known)
- Complete alarm message recorded
- Ventilation mode and settings documented
- Peak and plateau pressures recorded
- High-pressure alarm limit verified
- Patient circuit inspected
- Known-good circuit installed
- Filters and accessories removed or exchanged
- Inspiratory and expiratory valves inspected
- APL valve checked
- Test lung verified
- Scavenging system inspected
- Pressure waveform behavior documented
- System checkout completed
- Alarm function tested
- Final device status documented
Final Thought
High airway pressure can result from a simple kinked hose or a more serious ventilation-control fault. Protect the patient first, isolate external restrictions logically, verify operation through a complete checkout, and escalate any unresolved pressure abnormality. Accurate CCR documentation preserves the findings and supports safe follow-up.
That is successful troubleshooting.