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What This Guide Helps With
Helps isolate breathing-circuit leaks, gas-supply problems, bellows assembly issues, settings, connections, or scavenging effects when the ventilator bellows behaves abnormally.
Step-by-Step Troubleshooting
1. Protect the Patient and Maintain Ventilation
Do not troubleshoot abnormal ventilator bellows movement while a patient depends on the affected anesthesia machine. Provide alternate verified ventilation immediately.
Expected outcome: The patient is ventilated independently of the malfunctioning bellows system.
2. Confirm the Bellows Behavior
Determine whether the bellows fails to fill, partially fills, collapses completely, cycles irregularly, or behaves abnormally only during certain ventilation modes.
Reproduce the complaint on a test lung.
Expected outcome: The abnormal bellows behavior is clearly observed under controlled conditions.
3. Verify Ventilation Mode and Settings
Confirm the selected ventilation mode and externally accessible settings are appropriate for the test being performed.
Check for an unintended setting change that could make bellows movement appear abnormal.
Expected outcome: The ventilator is correctly configured. If correcting the setup restores normal bellows movement, proceed to final verification.
4. Inspect the Breathing Circuit for Leaks
Inspect all external breathing-circuit connections, patient Y-piece, bag, filters, sampling lines, adapters, absorber assembly, and accessible interfaces.
Expected outcome: The circuit is leak-free and correctly assembled. If correcting a leak restores bellows filling, troubleshooting can stop after final testing.
5. Check Fresh-Gas and Drive-Gas Availability
Confirm the anesthesia machine has the required gas supplies for normal ventilator operation and that no upstream pipeline or cylinder issue is present.
Expected outcome: Required gas sources are available and stable.
6. Inspect the Bellows Assembly Externally
With the unit removed from patient use, inspect the accessible bellows housing and visible bellows assembly for improper seating, obvious tears, distortion, obstruction, or incorrect installation.
Do not perform deep ventilator disassembly.
Expected outcome: The bellows assembly appears intact and properly seated. Visible damage requires removal from service.
7. Check for Expiratory or Scavenging Restrictions
Inspect the expiratory pathway and scavenging tubing for kinks, obstruction, excessive suction, incorrect connection, or conditions that could interfere with normal bellows filling.
Expected outcome: Gas can exit and the scavenging system does not create abnormal pressure effects.
8. Compare With a Known-Good External Circuit
Install a compatible known-good breathing circuit and test lung when appropriate.
Expected outcome: If normal bellows function returns, the removed circuit or accessory caused the problem. Replace the defective external component.
9. Perform Full Ventilation Verification
After correction, verify bellows movement, delivered ventilation, airway pressure, tidal volume, PEEP, breathing-system leakage, and alarms using approved test equipment.
Expected outcome: Bellows movement is consistent and ventilation performance is normal throughout testing. If so, troubleshooting is complete.
10. Remove From Service if Bellows Function Remains Abnormal
If gas supplies, circuit integrity, configuration, scavenging, and external bellows inspection are normal but bellows operation remains abnormal, stop external troubleshooting.
Expected outcome: The machine is removed from service for qualified ventilator and pneumatic evaluation.
If the Problem Persists
Common external circuit, gas-supply, configuration, bellows-seating, and scavenging causes have been ruled out. Remaining possibilities may involve internal ventilator drive gas, pneumatic valves, bellows control, pressure regulation, internal leakage, or other service-level faults.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using appropriate manufacturer documentation and approved anesthesia test equipment
- Repaired or adjusted only by qualified personnel
Complete ventilation-performance, breathing-system, alarm, gas-delivery, and safety testing before return to service.
Clinical Use Tip
Abnormal bellows movement should be treated as a ventilation reliability problem even if the machine continues cycling; transfer the patient to verified ventilation first.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Anesthesia staff reported the ventilator bellows would collapse and not refill normally during pre-case testing."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found a large leak at a loose breathing-circuit connection."
Resolution
What action was taken.
Example:
"The connection was secured and normal bellows operation, ventilation, leak performance, pressures, and alarms were verified with approved test equipment."
Helpful Details to Include (If Known)
- Bellows behavior observed
- Ventilation mode
- Gas sources available
- Circuit leak-test result
- Bellows external condition
- Scavenging configuration
- Known-good circuit result
- Test-lung performance
- Alarm behavior
- Final device status
- Bellows behavior observed
- Ventilation mode
- Gas sources available
- Circuit leak-test result
- Bellows external condition
- Scavenging configuration
- Known-good circuit result
- Test-lung performance
- Alarm behavior
- Final device status
Final Thought
Bellows behavior reflects the performance of the entire ventilation and breathing-system path. Start with patient safety, then verify settings, gas supply, circuit integrity, scavenging, and accessible components before escalating suspected internal ventilator faults.
That is successful troubleshooting.