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What This Guide Helps With
Troubleshooting elevated airway pressure caused by circuit restrictions, incorrect settings, patient-side accessories, expiratory obstruction, scavenging problems, or breathing-system components.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not perform extended troubleshooting while the Aisys CS2 is supporting an active patient.
If a high-airway-pressure alarm occurs during clinical use:
- Notify the anesthesia provider immediately.
- Have the provider assess the patient, airway, endotracheal tube, and clinical causes.
- Confirm whether ventilation and oxygenation remain adequate using independent monitoring.
- Move the patient to another verified anesthesia machine or approved ventilation method when reliable ventilation cannot be maintained.
- Follow the facility’s anesthesia-equipment failure procedure.
Expected outcome: Patient care no longer depends on equipment with unresolved elevated airway pressure.
Continue equipment troubleshooting only after the machine is safely removed from patient use.
2. Confirm the Exact Alarm Condition
Record the complete alarm message and determine:
- Whether airway pressure remains continuously elevated or rises only during inspiration.
- Whether the alarm occurs in mechanical ventilation, manual ventilation, or both.
- Whether the displayed pressure reaches the configured pressure limit.
- Whether the condition occurs with every breathing circuit or only a particular setup.
- Whether the bellows and pressure waveform behave normally.
Review the alarm history when available.
Expected outcome: The failure pattern is clearly identified before components are changed.
3. Check Ventilator and Alarm Settings
Verify that the selected ventilation parameters are appropriate for testing, including:
- Tidal volume or inspiratory pressure
- Respiratory rate
- Inspiratory time and I ratio
- PEEP setting
- Pressure-limit setting
- Ventilation mode
- Fresh-gas flow
Excessive tidal volume, inspiratory pressure, PEEP, or inspiratory time can cause airway pressure to reach the configured alarm limit.
Use a test lung and approved test settings rather than changing clinical settings on a patient.
Expected outcome: Pressure remains below the configured limit during controlled testing.
If correcting an inappropriate setting resolves the alarm, complete the required system checkout and stop.
4. Inspect the Patient Breathing Circuit
Examine the entire circuit from the machine to the test lung for:
- Kinked or compressed tubing
- Tubing trapped beneath equipment
- Internal circuit collapse
- Blocked connectors or elbows
- Incorrectly assembled breathing-circuit components
- Excessive water accumulation
- Closed or obstructed valves on attached accessories
Straighten the circuit, drain moisture safely, or replace the circuit with a known-good compatible set.
Expected outcome: Gas flows freely through the complete breathing circuit without excessive resistance.
If replacing the circuit resolves the alarm, perform a checkout and stop.
5. Remove External Accessories
Temporarily remove nonessential patient-side accessories, including:
- Heat-and-moisture exchangers
- Bacterial or viral filters
- Catheter mounts
- Flexible elbows
- Closed-suction adapters
- Specialty airway connectors
- Additional sampling adapters
Inspect each accessory for contamination, liquid accumulation, blockage, or incorrect orientation.
Reconnect only the minimum components needed for testing.
Expected outcome: Airway pressure remains stable with unnecessary resistance removed.
If one accessory recreates the alarm, replace that accessory and stop after successful verification.
6. Check the Test Lung and Simulated Airway
Confirm that the test lung:
- Is not obstructed or internally damaged.
- Has appropriate compliance and resistance.
- Is connected securely.
- Is not compressed against the table or equipment.
- Is suitable for the selected tidal volume or pressure.
Test with a second known-good test lung when available.
Expected outcome: The machine ventilates a verified test load without reaching the high-pressure limit.
7. Inspect the Inspiratory and Expiratory Connections
Verify that the inspiratory and expiratory hoses are connected to the correct ports and are fully seated.
Inspect the external breathing-system ports for:
- Foreign material
- Liquid accumulation
- Damaged sealing surfaces
- Loose connections
- Misconnected hoses
Do not insert tools into valves or internal gas pathways.
Expected outcome: Both breathing-system pathways are correctly connected and externally unobstructed.
8. Check the Expiratory Path and Scavenging System
Look for external conditions that could prevent normal exhalation:
- Kinked expiratory tubing
- Excessive moisture
- Obstructed expiratory accessories
- Improperly connected scavenging hoses
- Restricted AGSS tubing
- Excessive suction from the waste-gas receiving system
- Incorrect scavenging flow adjustment
Temporarily evaluate the machine with a verified scavenging setup according to facility procedures.
Expected outcome: Exhaled gas exits normally, and pressure returns toward baseline between breaths.
9. Check Manual Ventilation Operation
With a test lung installed, place the system in manual ventilation and verify:
- The bag fills normally.
- The bag is not unusually difficult to compress.
- Pressure falls after the bag is released.
- The APL valve is not set unnecessarily high.
- The APL valve adjusts through its normal external range.
The APL valve controls pressure during manual ventilation and is adjustable up to 70 cmH₂O on the Aisys CS2.
Expected outcome: Manual ventilation produces controlled pressure that decreases normally during exhalation.
If pressure remains trapped in manual ventilation, remove the machine from service.
10. Inspect Accessible Breathing-System Components
With the device powered down and removed from clinical use, visually inspect user-removable breathing-system components for:
- Incorrect installation
- Missing seals
- Damaged O-rings
- Warped components
- Moisture or contamination
- Components not fully locked into position
Reseat components only as permitted by the operator documentation and Clinical Engineering procedures.
Do not disassemble internal valves, manifolds, or ventilator assemblies during initial troubleshooting.
Expected outcome: All accessible components are clean, intact, and correctly installed.
11. Restart and Perform the Required Checkout
Reconnect the machine to verified electrical and gas supplies, then:
- Power-cycle the Aisys CS2.
- Allow startup to complete without interruption.
- Perform the manufacturer-required preoperative checkout.
- Complete the leak and compliance checks.
- Test ventilation with a known-good circuit and test lung.
- Observe the pressure waveform and confirm that pressure returns to baseline.
GE instructs users to follow the Aisys CS2 reference documentation for complete operation and checkout requirements.
Expected outcome: The machine completes checkout and ventilates the test lung without an unexpected high-airway-pressure alarm.
If the checkout passes and the alarm cannot be reproduced, document all findings and return the device according to facility policy.
If the Problem Persists
If the alarm continues with verified settings, a known-good circuit, minimal accessories, a verified test lung, and an unobstructed scavenging setup, common external causes have been ruled out.
The condition may involve an internal:
- Inspiratory or expiratory valve
- Flow-control component
- Pressure sensor
- Ventilator assembly
- Breathing-system manifold
- Electronic control or calibration fault
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for qualified repair or bench evaluation
- Evaluated using the appropriate GE Healthcare service documentation and approved test equipment
Do not continue replacing external parts or repeatedly cycling the machine when airway pressure cannot be reliably controlled. Knowing when to stop and escalate is proper troubleshooting.
Clinical Use Tip
Never troubleshoot a high-airway-pressure condition by repeatedly ventilating an active patient. The anesthesia provider must first evaluate patient, airway, positioning, and clinical causes. Equipment testing should continue only with a verified test lung after the patient is safely supported elsewhere.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Clinical staff reported repeated high-airway-pressure alarms during mechanical ventilation on the GE Healthcare Aisys CS2."
Cause
What was observed during troubleshooting.
Example:
"Inspection found a moisture-saturated bacterial filter restricting flow at the patient connection and causing peak pressure to reach the configured limit."
Resolution
What action was taken.
Example:
"Replaced the restricted filter, installed a known-good circuit, completed the system checkout, and verified normal pressure and ventilation using a test lung."
Helpful Details to Include (If Known)
- Complete alarm wording recorded
- Ventilation mode and settings documented
- Pressure-limit and PEEP settings checked
- Peak and baseline pressure observed
- Known-good circuit installed
- Filters and accessories removed or replaced
- Test lung exchanged
- Inspiratory and expiratory hoses checked
- Moisture or obstruction found
- Scavenging setup inspected
- APL valve operation checked
- Checkout and leak test results
- Alarm history reviewed
- Final device status documented
Final Thought
High airway pressure may result from the patient, airway, breathing circuit, settings, accessories, scavenging system, or the anesthesia machine itself. Patient safety comes first, followed by controlled external checks and testing with known-good components. When pressure remains abnormal after external causes are eliminated, remove the Aisys CS2 from service and escalate for repair. Clear CCR documentation preserves the reported condition, findings, corrective action, and final equipment status.
That is successful troubleshooting.