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Continuous Renal Replacement Therapy (CRRT)
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Model
What This Guide Helps With
This guide helps troubleshoot the Baxter PrismaFlex Access Extremely Negative alarm. This alarm can occur when access pressure becomes excessively negative due to catheter restriction, access-line obstruction, excessive blood flow demand, patient or catheter position changes, disposable set issues, or pressure-sensing failure.
The condition may interrupt CRRT therapy, stop or slow the blood pump, or indicate poor blood withdrawal from the patient access catheter.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- Confirm the patient is being safely supported while the access-pressure alarm is evaluated.
- Do not continue troubleshooting on an active treatment if blood flow is compromised or the alarm cannot be resolved quickly.
- Notify clinical staff and follow facility protocol for CRRT interruption, blood return, anticoagulation concerns, and access catheter management.
- If therapy must continue, move the patient to a backup CRRT device or alternate therapy plan according to facility procedure.
Expected: Patient care is maintained safely while the access-pressure issue is evaluated.
Why it matters: An unresolved access pressure alarm can indicate poor blood withdrawal from the catheter and may interrupt therapy or contribute to circuit complications.
Verify the Reported Alarm and Behavior
- Confirm the exact displayed alarm is Access Extremely Negative.
- Observe whether the alarm occurs during startup, shortly after treatment begins, after patient movement, during coughing or suctioning, during transport, or only at higher blood flow rates.
- Check whether the blood pump stops, slows, or repeatedly alarms after clearing.
- Review whether access pressure is trending more negative before the alarm occurs.
- Look for visible line movement, tubing collapse, clamps, kinks, or poor catheter blood withdrawal reported by clinical staff.
Expected: The alarm is confirmed and linked to access pressure becoming excessively negative.
Why it matters: This helps separate a true access-pressure problem from a one-time nuisance alarm or operator misinterpretation.
Allow the Self-Clearing Attempt When Appropriate
- If the patient is stable and no unsafe condition is visible, allow the PrismaFlex to complete the short self-clearing attempt.
- Watch whether the alarm clears after a brief movement, cough, suction event, or temporary catheter position change.
- If the alarm clears and does not return, continue monitoring the treatment closely.
- If the alarm repeats, continue with external checks.
Expected: A transient access-pressure drop clears and does not immediately return.
Why it matters: Brief patient movement or catheter position changes can temporarily create excessive negative access pressure.
Check the Access Line for External Obstruction
- Inspect the access line from the patient catheter to the PrismaFlex set.
- Check for closed or partially closed clamps.
- Look for kinked, twisted, compressed, or trapped tubing.
- Verify tubing is not under the bed rail, patient, blanket, equipment, or transport hardware.
- Check for line tension pulling on the access catheter.
- Observe whether the tubing collapses during blood pump operation.
- Correct any obvious external obstruction.
Expected: The access line is open, unkinked, properly routed, and free of tension.
Why it matters: A clamped or restricted access line can cause the pump to pull harder against the access source, making access pressure extremely negative.
Check for Patient Movement or Catheter Position Effects
- Ask clinical staff whether the alarm started after patient repositioning, coughing, suctioning, sitting up, turning, transport, line manipulation, or catheter dressing changes.
- With nursing or clinical staff, verify the access catheter is not being pulled, bent, compressed, or positioned against the vessel wall.
- Observe whether access pressure improves when the patient or catheter position is adjusted by qualified clinical staff.
Expected: Access pressure improves when the patient and catheter are positioned appropriately.
Why it matters: A malpositioned catheter can intermittently occlude against the vessel wall and create very negative access pressure.
Have Clinical Staff Evaluate the Access Catheter
- Ask qualified clinical staff to assess the access catheter according to hospital protocol.
- Clinical checks may include blood withdrawal assessment, flushing per protocol, patient repositioning, catheter repositioning, dressing assessment, or evaluation for clotting or malposition.
- Clinical Engineering should not manipulate the catheter directly unless facility policy specifically allows it.
Expected: The catheter provides adequate blood withdrawal for the ordered blood flow rate.
Why it matters: A clotted, malpositioned, or partially occluded catheter is a common cause of extremely negative access pressure.
Compare Blood Flow Rate to Access Capability
- Review the prescribed blood flow rate and the access device being used.
- If the alarm occurs mostly at higher blood flow rates, ask clinical staff to reduce blood flow only according to protocol and provider direction.
- Observe whether access pressure becomes less negative at a lower blood flow rate.
- Document whether lowering blood flow stabilizes the alarm.
Expected: Access pressure improves if the blood flow demand was exceeding what the catheter could provide.
Why it matters: If the blood pump demand exceeds the catheter’s ability to supply blood, the system may generate excessive negative access pressure.
Inspect the Pressure Pod and Set Interface
- Check that the access pressure pod is correctly seated.
- Verify nearby tubing is fully positioned in the pressure-sensing area.
- Look for moisture, leakage, or contamination near the pressure pod.
- Inspect for damaged, collapsed, or deformed tubing.
- Verify the disposable set appears correctly loaded.
- If the disposable set appears compromised and cannot be corrected safely, follow facility protocol for treatment interruption or set change.
Expected: The disposable set and access pressure pod are correctly installed with no visible leakage or damage.
Why it matters: The PrismaFlex relies on accurate pressure sensing to detect access pressure changes. A poorly seated or compromised pod can cause false or unstable pressure readings.
Determine Whether the Issue Is Access-Related or Device-Related
- If the alarm follows patient movement, catheter function, catheter position, or blood flow rate, suspect an access-related cause.
- If the alarm occurs with no obstruction, stable catheter function, correct set loading, and normal operating conditions, suspect a device pressure-sensing issue.
- Reasonably rule out the access line, catheter, blood flow setting, disposable set, and pressure pod before sending the machine for repair.
Expected: Troubleshooting narrows the issue to an accessory, disposable set, catheter, blood flow setting, or device pressure-sensing problem.
Why it matters: The device should not be sent for repair until external and access-related causes have been reasonably ruled out.
Escalate for Pressure-Sensing Evaluation if Needed
- If the alarm persists after line, catheter, flow, pressure pod, and setup checks are complete, remove the PrismaFlex from use.
- Label the device Out of Service.
- Send the unit for bench evaluation by Clinical Engineering or authorized service.
- Evaluate access pressure sensor operation, ARPS circuit leakage, pressure-sensor calibration, pressure reading stability, and sensor deviation from expected values.
Expected: Faulty pressure-sensing hardware is identified, calibrated if appropriate, or replaced if deviation remains.
Why it matters: A failed or drifting access pressure sensor can cause repeated false or unresolved Access Extremely Negative alarms.
If the Problem Persists
If the alarm continues after the access line, patient position, catheter function, blood flow rate, pressure pod, and disposable set have been checked, external and common access-related causes have been ruled out.
A persistent Access Extremely Negative alarm may indicate a pressure-sensing fault, ARPS leakage, calibration issue, or internal device failure.
Remove the PrismaFlex from service, label it Out of Service, and send it for repair or bench evaluation.
Knowing when to stop is proper troubleshooting.
Clinical Use Tip
Never troubleshoot an unresolved access pressure alarm on an active patient longer than clinically appropriate. Move the patient to a backup device or alternate therapy plan first, and involve nursing or the provider for catheter assessment, flushing, repositioning, or blood-flow adjustments.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"PrismaFlex removed from CRRT use due to Access Extremely Negative alarm. Staff reported alarm during treatment with access pressure becoming excessively negative and blood pump interruption."
Cause
What was observed during troubleshooting.
Example:
"Access line and external routing were inspected. No clamp or kink found. Alarm persisted after patient repositioning and blood flow reduction. Catheter issue ruled out by clinical staff. Suspect access pressure-sensing or ARPS circuit fault."
Resolution
What action was taken.
Example:
"Device removed from service and labeled Out of Service. Sent for bench evaluation of access pressure sensor, ARPS circuit leakage, and pressure-sensor calibration. Repair required before return to patient use."
Helpful Details to Include (If Known)
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
The Access Extremely Negative alarm should be treated as a real blood access concern first, not immediately as a device failure. Start with patient safety, line patency, catheter position, and blood flow demand. Once those are ruled out, persistent alarms justify pressure-sensing evaluation and service escalation. Good documentation connects the displayed alarm to the clinical symptom, the checks performed, and the final disposition.
That is successful troubleshooting.