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Asset Type
Extracorporeal Membrane Oxygenation (ECMO) System
Manufacturer
Model
What This Guide Helps With
Troubleshoots bubble alarms and failed sensor checks involving tubing placement, sensor contact, contamination, cabling, circuit condition, and external setup.
Step-by-Step Troubleshooting
1. Treat a Bubble Alarm as Clinically Significant
During ECMO support, do not assume a bubble alarm is false. Notify the clinical ECMO team immediately and follow the institution's air-management and ECMO emergency procedures.
Clinical staff must determine whether air is actually present and manage the patient-connected circuit.
Expected outcome: Potential air in the extracorporeal circuit is addressed clinically before technical troubleshooting begins.
2. Confirm Whether the Problem Is an Alarm or Test Failure
Determine whether the reported condition is:
- A bubble alarm during operation
- A failed pre-use detector test
- Intermittent detection
- Sensor not recognized
- Alarm that occurs only after tubing movement
- An alarm or test failure that remains with a non-patient test circuit
Document the exact displayed message or behavior.
Expected outcome: The technical problem is distinguished from a genuine clinical bubble event.
3. Inspect Tubing Position in the Detector
On a safe setup, verify the intended tubing section is correctly positioned in the bubble detector.
Check for:
- Tubing not fully seated
- Incorrect tubing size or incompatible setup
- Tubing twisted or flattened
- Tubing pulling away from the sensing surface
- Improper detector closure or positioning
Expected outcome: Tubing sits securely and consistently in the intended sensing position. If correction restores normal detection, proceed to verification.
4. Inspect the Sensor Area for Contamination
Inspect accessible detector surfaces for:
- Moisture
- Blood or fluid contamination
- Residue
- Debris
- Damage
Clean reusable surfaces only with approved methods.
Expected outcome: The detector interface is clean, dry, and undamaged.
5. Inspect Sensor Cable and Connections
Verify the detector cable is correctly connected and inspect it for cuts, pinching, connector damage, strain, or intermittent connection.
Expected outcome: The sensor remains recognized with a stable external connection.
6. Evaluate the Circuit Segment
On an approved test circuit, inspect the tubing segment passing through the detector for conditions that could interfere with sensing, including unusual surface condition, deformation, condensation, or inappropriate positioning.
Do not manipulate patient-connected tubing without the ECMO clinical team.
Expected outcome: The tubing segment is appropriate for reliable bubble detection.
7. Perform the Approved Sensor Test
Run only the normal user-accessible bubble-detector check or test specified for routine setup. Do not bypass or disable bubble detection to clear a failed test.
Expected outcome: The detector passes the approved test and returns to a normal monitoring state. If it does, continue to final verification.
8. Compare With Known-Good External Components
When available, use a known-good compatible detector cable, sensor assembly, or approved test setup as applicable without entering restricted service procedures.
Expected outcome: Comparison identifies whether the problem follows the external sensor component or remains with the system.
9. Perform Final Functional Verification
Before return to service, verify:
- Detector is recognized
- Approved bubble-detector test passes
- Tubing remains correctly positioned
- Alarm audio and visual indications are available
- No unexplained bubble alarms occur on the controlled test setup
Expected outcome: Bubble detection is reliable and all required alarm functions pass. Troubleshooting can stop.
10. Escalate an Unresolved Detector Problem
If the test continues to fail or alarms occur without an explainable external cause, remove the equipment from service.
Expected outcome: The device is prevented from clinical use until qualified evaluation confirms reliable bubble detection.
If the Problem Persists
Tubing placement, contamination, external connections, sensor setup, and routine detector testing have been addressed. Remaining possibilities include the detector assembly, signal processing, internal communication, or another service-level problem.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using appropriate Getinge documentation and approved test equipment
- Repaired or configured only by qualified personnel
Never bypass a bubble detector, suppress a persistent alarm, or return an ECMO system to service with unreliable air detection. Complete required alarm and detector verification following repair.
Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
Any bubble alarm on a patient-connected ECMO circuit must be treated as a possible true air event until the clinical ECMO team determines otherwise.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"ECMO staff reported the ROTAFLOW II bubble detector failed its setup test before patient use."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found the circuit tubing was not fully seated in the bubble detector sensing area."
Resolution
What action was taken.
Example:
"Correctly positioned the tubing, repeated the approved detector test successfully, verified alarm operation, and returned the system to service."
Helpful Details to Include (If Known)
- Exact bubble alarm or test message
- Whether patient was connected
- Detector test result
- Tubing position and condition
- Detector surface condition
- Sensor cable and connector condition
- Whether tubing movement affected the alarm
- Known-good comparison result
- Alarm audio and visual verification
- Final device status
Final Thought
Protect the patient from possible circuit air first, verify the complete external sensing setup, never bypass an unreliable detector, and document both the identified cause and successful alarm verification.
That is successful troubleshooting.