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What This Guide Helps With
Troubleshoots inaccurate PEEP or APL pressure caused by circuit setup, leaks, valve positioning, accessories, pressure measurement, contamination, or external configuration.
Step-by-Step Troubleshooting
1. Protect the Patient and Establish Alternate Ventilation
Do not troubleshoot questionable PEEP or APL pressure while a patient depends on the machine.
If airway pressure cannot be trusted, provide ventilation using another verified anesthesia machine or appropriate alternate method.
Expected outcome: Patient support is maintained independently of the equipment being tested.
2. Confirm Which Pressure-Control Function Is Affected
Determine whether the complaint involves:
- APL valve behavior during manual or spontaneous ventilation
- PEEP during mechanical ventilation
- Pressure higher than expected
- Pressure lower than expected
- Pressure that will not remain stable
- A setting that does not correspond with observed pressure behavior
Test under controlled non-patient conditions.
Expected outcome: The affected function and reproducible symptom are clearly identified.
3. Inspect the Breathing Circuit
Inspect the breathing circuit for:
- Loose connections
- Disconnected limbs
- Cracked tubing
- Incorrect assembly
- Damaged reservoir bag
- Improperly seated components
- Occlusion or kinking
Correct or replace questionable disposable components.
Expected outcome: The circuit is complete, unobstructed, and leak-free externally. If correcting the circuit restores expected pressure behavior, troubleshooting can stop after verification.
4. Verify the APL Valve Position and Movement
For an APL-related complaint, confirm that the valve is set appropriately for the intended test and that the external control moves smoothly through its normal operating range.
Inspect for:
- Binding
- Physical damage
- Contamination
- Objects restricting movement
- Incorrect user positioning
Do not disassemble the valve.
Expected outcome: The APL control moves freely and the observed pressure response changes appropriately with external adjustment.
5. Verify PEEP Settings and Ventilation Mode
For a PEEP-related complaint, confirm that:
- The selected ventilation mode supports the intended setting
- The displayed setting is correct
- No unintended configuration or mode selection is affecting the test
- The machine is in the proper operating state for the measurement being evaluated
Do not change protected configuration parameters unless authorized.
Expected outcome: The operating mode and user-adjustable settings match the intended test condition.
6. Check for Breathing-System Leaks
Perform the appropriate manufacturer-approved leak or pre-use test.
Inspect accessible seals, circuit interfaces, absorber connections, bag connection, and other external components when a leak is indicated.
Expected outcome: The breathing system passes the applicable leak evaluation. If an external leak is found and corrected, repeat the pressure test.
7. Use a Known-Good Test Lung and Circuit When Appropriate
Substitute a compatible known-good test lung, breathing circuit, reservoir bag, or other external accessory to isolate questionable disposables or accessories.
Expected outcome: Pressure behavior becomes stable with known-good accessories, identifying the replaced external component as the cause.
8. Verify Pressure With Approved Test Equipment
If the displayed or delivered pressure remains questionable, evaluate it using appropriate calibrated test equipment and the applicable manufacturer procedure.
Do not infer accuracy from display appearance alone.
Expected outcome: Independent testing confirms whether the machine's pressure behavior is acceptable or genuinely abnormal.
9. Inspect Accessible Valve Areas for External Contamination or Damage
Inspect externally accessible valve surfaces and adjacent breathing-system components for:
- Moisture
- Residue
- Debris
- Visible damage
- Improper assembly after cleaning
Follow approved cleaning and assembly instructions without performing deep disassembly.
Expected outcome: Accessible components are clean, properly assembled, and free from obvious mechanical restriction.
10. Perform Final Functional Verification
After any external correction, repeat the appropriate breathing-system test and verify:
- Stable pressure
- Expected APL response when applicable
- Expected PEEP behavior when applicable
- No abnormal leakage
- Normal alarms and ventilation operation
- Successful pre-use testing
Expected outcome: Pressure behavior is stable and verified with the appropriate test method. If successful, troubleshooting is complete.
11. Remove From Service if Pressure Cannot Be Verified
If pressure remains inaccurate, unstable, or inconsistent with the selected settings, stop troubleshooting and remove the machine from clinical use.
Expected outcome: Equipment with uncertain airway-pressure control is not returned to patient care.
If the Problem Persists
External circuit assembly, accessories, user-adjustable valve positioning, ventilation settings, leaks, and test setup have been ruled out.
The remaining condition may involve an internal valve mechanism, pressure-sensing system, pneumatic pathway, calibration issue, or other service-level fault.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using appropriate manufacturer documentation and approved test equipment
- Repaired or calibrated only by qualified personnel
After service, complete the required pressure, ventilation, alarm, and anesthesia-machine return-to-service testing before clinical use.
Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
Any anesthesia machine with questionable airway-pressure control should be replaced before patient use rather than evaluated during active ventilation.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Anesthesia staff reported that manual ventilation pressure on the Aespire did not respond normally to APL valve adjustment."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found the reservoir bag connection partially loose, producing an external breathing-system leak and unstable pressure."
Resolution
What action was taken.
Example:
"Reseated the reservoir bag connection, repeated the breathing-system leak and pressure checks, and verified normal APL response during functional testing."
Helpful Details to Include (If Known)
- Whether APL or PEEP was affected
- Manual or mechanical ventilation mode
- Reported high, low, or unstable pressure
- Circuit and reservoir bag condition
- Leak-test result
- Valve movement
- Ventilation mode and settings observed
- Known-good circuit or test-lung substitution
- Independent pressure-test result
- Visible contamination or moisture
- Final functional-test result
- Final device status
Final Thought
Airway-pressure concerns require verified testing, not assumptions. Start with circuit assembly, leaks, accessories, controls, and settings, confirm the pressure using appropriate test equipment, and escalate when reliable pressure control cannot be demonstrated.
That is successful troubleshooting.