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Asset Type
Continuous Renal Replacement Therapy (CRRT)
Manufacturer
Model
What This Guide Helps With
This guide assists Clinical Engineering in troubleshooting air bubble detector alarms on the PrismaFlex system. These alarms typically indicate air detected in the extracorporeal circuit or issues with the air detector sensor. The focus is on identifying external causes such as setup issues, loose connections, or fluid path problems before assuming internal sensor failure.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- Never troubleshoot while the patient is actively connected to the device
- Transition the patient to another machine before proceeding
- Air bubble alarms are a critical safety mechanism to prevent air embolism
Verify the alarm message and location
- Confirm whether the alarm is identifying air in the arterial line, venous return line, or within the cartridge
- This helps narrow down where the issue is occurring in the circuit
Check for visible air in the bloodlines
- Inspect all tubing segments for air bubbles or foam
- Even small bubbles can trigger sensitive air detectors
Ensure proper priming of the circuit
- Confirm the circuit was fully primed according to procedure
- Incomplete priming is one of the most common causes of repeated air alarms
Inspect all connections and luer locks
- Check for loose, cracked, or improperly seated connections
- Air can be introduced into the system through even minor leaks
Check fluid bags and lines for depletion or air introduction
- Ensure replacement fluids and dialysate bags are not empty and lines are properly submerged
- Air may enter if a bag runs dry or tubing is not properly positioned
Verify proper placement of tubing in the air detector
- Ensure the tubing is correctly seated in the air bubble detector clamp
- Misalignment can cause false alarms
Clean the air detector sensor area
- Inspect for moisture, residue, or debris on the sensor window
- Contamination can interfere with ultrasonic detection
Check for kinks or occlusions in the tubing
- Kinks can cause turbulent flow and introduce microbubbles that trigger alarms
Observe for excessive foaming in the circuit
- Foam can be interpreted as air by the detector
- This may indicate blood-air interface issues or improper setup
Power cycle the system (if clinically appropriate)
- Restart the machine to rule out a transient sensor or software issue
- Only perform this step when the patient is safely off therapy
If the Problem Persists
If air bubble alarms continue after verifying proper setup, connections, and priming, the issue is likely internal (e.g., faulty air detector sensor or control board).
- Remove the device from service
- Label as Out of Service
- Send for repair or perform bench evaluation
Recognizing when external causes have been ruled out is an important part of proper troubleshooting.
Clinical Use Tip
Never troubleshoot air bubble alarms while the patient is actively connected. Always transition the patient to another machine before addressing the issue to prevent the risk of air embolism.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
“Unit alarming ‘Air Bubble Detected’ and unable to continue therapy.”
Cause
What was observed during troubleshooting.
Example:
“Air observed in venous return line due to incomplete priming and loose luer connection.”
Resolution
What action was taken.
Example:
“Re-primed circuit, secured all connections, verified no air present, and confirmed normal operation.”
Helpful Details to Include (If Known)
- Circuit fully primed
- All connections tightened and verified
- Tubing correctly seated in detector
- No visible air or foam present
- Fluid bags checked (not empty)
- Sensor area clean and dry
- Alarm behavior consistent or intermittent
- Final device status (returned to service or sent for repair)
Final Thought
Air bubble alarms are critical safety features designed to prevent serious patient harm. A structured approach—starting with setup, fluid path, and connection checks—will resolve most issues quickly. When the problem persists, escalation is the correct and safe decision. Clear documentation ensures continuity and supports future troubleshooting.
That is successful troubleshooting.