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What This Guide Helps With
Troubleshooting failed, incomplete, inconsistent, or unavailable noninvasive blood pressure measurements caused by cuff, hose, connection, setup, motion, or device faults.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not troubleshoot an unreliable NIBP function while the LIFEPAK 35 is being relied upon for active patient monitoring.
Move the patient to another verified blood pressure monitoring method or known-good monitor before extended troubleshooting.
Expected: Patient care continues without dependence on an unresolved NIBP measurement problem.
Why it matters: NIBP results support clinical assessment, and repeated failed or questionable measurements should not delay obtaining a reliable blood pressure by another appropriate method.
2. Verify the Reported Failure
Confirm exactly what occurs when an NIBP measurement is initiated.
Check whether the device:
- Does not start cuff inflation
- Inflates briefly and stops
- Repeatedly reinflates
- Takes unusually long to complete
- Deflates before displaying a result
- Produces intermittent failures
- Displays an NIBP-related message
- Produces measurements that are inconsistent with a reference method
Record the exact displayed message or behavior when available.
Expected: The failure pattern is clearly identified before components are exchanged.
If the problem is not reproducible and repeated controlled measurements complete normally, continue functional verification before returning the device to service.
3. Inspect the NIBP Cuff
Remove the cuff from clinical use for inspection.
Check for:
- Tears or punctures
- Damaged bladder material
- Loose tubing
- Cracked fittings
- Worn hook-and-loop closure
- Contamination
- Incorrect cuff size
- A cuff that does not remain securely wrapped
Replace a visibly damaged or questionable cuff with a known-good compatible cuff.
Expected: The cuff is intact, correctly sized, and capable of maintaining pneumatic pressure.
If replacing the cuff resolves the issue, verify repeat measurements and stop troubleshooting.
4. Verify Cuff Size and Application
Confirm the cuff size is appropriate for the test subject or approved simulator setup.
For controlled testing on a person, verify:
- Correct cuff size
- Secure application
- Proper positioning
- No clothing trapped beneath the cuff
- No excessive looseness
- Minimal movement during measurement
Expected: The cuff inflates and completes a measurement without excessive reinflation or premature termination.
Why it matters: Incorrect sizing, poor placement, and movement can prevent reliable oscillometric measurements even when the monitor is functioning normally.
If correct application resolves the issue, complete repeat testing and stop.
5. Inspect the NIBP Hose
Examine the complete hose from the cuff to the LIFEPAK 35.
Check for:
- Kinks
- Crushing
- Cuts
- Cracks
- Loose fittings
- Damaged connectors
- Contamination
- Signs of stretching or repeated strain
Straighten any kinked tubing and replace a damaged hose.
Expected: The pneumatic path is open and free of visible leakage or restriction.
If the issue resolves with a known-good hose, document the failed accessory and stop.
6. Reseat All Pneumatic Connections
Disconnect and reconnect:
- Hose to cuff
- Hose to the LIFEPAK 35 NIBP connection
Confirm each connection is fully seated and mechanically secure.
Do not force a connector that does not fit correctly.
Expected: Connections remain secure during inflation and do not leak or separate.
If reseating the connections restores reliable measurements, repeat testing and stop.
7. Substitute Known-Good Compatible Accessories
Using approved compatible accessories, test with:
- A known-good cuff
- A known-good NIBP hose
Change one component at a time when practical so the failed item can be identified.
Expected: A repeatable accessory-related failure is isolated.
Interpretation:
- Failure disappears with another cuff: suspect original cuff leakage or damage.
- Failure disappears with another hose: suspect original hose or connector.
- Failure remains with both known-good accessories: continue troubleshooting.
8. Check for Pneumatic Leak Behavior
Initiate a controlled NIBP measurement and observe inflation behavior without disassembling the device.
Look for:
- Little or no inflation
- Inflation followed by rapid pressure loss
- Repeated pumping
- Unusually prolonged inflation
- Audible air leakage
- Failure only when the hose or connector is moved
Do not repeatedly cycle a visibly damaged pneumatic system.
Expected: Inflation is smooth, the cuff maintains pressure as required during the measurement cycle, and controlled deflation occurs normally.
If external leakage is found, replace the affected cuff or hose and retest.
9. Rule Out Motion and Test-Condition Problems
Repeat the measurement under stable conditions.
For a controlled human-subject check, ensure the subject is:
- Still
- Not talking
- Not actively moving the limb
- Properly positioned
For bench evaluation, use the organization’s approved NIBP analyzer and established test procedure.
Expected: The measurement completes consistently under controlled conditions.
If the failure occurs only with movement or poor application but not during controlled testing, the monitor itself may be functioning normally.
10. Review NIBP Settings and Operating State
Verify that the intended NIBP measurement mode and associated settings are appropriate for the test.
Check for:
- An unintended interval or automatic measurement configuration
- Incorrect patient-related setup where applicable
- A measurement cycle already in progress
- A displayed condition requiring attention before another measurement
- Other active device faults occurring at the same time
Expected: The NIBP function is configured appropriately and accepts a normal measurement request.
If correcting the setup resolves the issue, repeat testing and stop.
11. Perform a Controlled Restart
Only after the device is removed from patient use:
- End active monitoring or testing.
- Power the LIFEPAK 35 off normally.
- Wait briefly.
- Restart the device.
- Observe startup behavior.
- Repeat NIBP testing with known-good accessories.
Expected: The device starts normally and NIBP measurements complete consistently.
If the problem resolves, perform repeated functional verification before return to service.
12. Perform Clinical Engineering Functional Verification
Using approved test equipment and your facility’s established inspection procedure:
- Connect a known-good compatible NIBP hose
- Use the appropriate approved NIBP analyzer setup
- Test repeated measurement cycles
- Compare displayed values with analyzer targets within applicable test tolerances
- Observe inflation, deflation, measurement completion, and repeatability
- Confirm no related fault messages occur
Do not rely on a single successful reading after an intermittent failure.
Expected: NIBP measurements complete repeatedly and meet the organization’s applicable performance requirements.
If the device fails controlled testing with known-good accessories, stop external troubleshooting and escalate.
If the Problem Persists
If the LIFEPAK 35 continues to fail NIBP measurements after:
- Correct cuff sizing and application are verified
- Cuff condition is verified
- Hose condition is verified
- Connections are reseated
- Known-good compatible accessories are substituted
- Motion and test conditions are controlled
- Settings are reviewed
- Controlled functional testing is performed
then common external causes have been reasonably ruled out.
The issue may involve the internal NIBP pneumatic or monitoring system and requires qualified repair evaluation.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
Do not continue repeated measurement attempts or begin unnecessary internal disassembly without the appropriate authorized service process.
Knowing when to stop is proper troubleshooting.
Clinical Use Tip
Do not troubleshoot unreliable NIBP measurements on an active patient. Transfer blood pressure monitoring to another verified method or device first, then evaluate the LIFEPAK 35 under controlled conditions.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Clinical staff reported that the LIFEPAK 35 repeatedly inflated the NIBP cuff but failed to display a blood pressure measurement."
Cause
What was observed during troubleshooting.
Example:
"Inspection found the NIBP hose leaking near the cuff-side connection, and the failure did not recur with a known-good compatible hose."
Resolution
What action was taken.
Example:
"Replaced the damaged NIBP hose, completed repeated controlled NIBP measurements, verified acceptable operation, and returned the defibrillator to service."
Helpful Details to Include (If Known)
- Exact NIBP message or symptom recorded
- Failure reproduced
- Correct cuff size verified
- Cuff inspected
- Known-good cuff tested
- NIBP hose inspected
- Known-good hose tested
- Connections reseated
- Leak behavior observed
- Motion ruled out
- Settings reviewed
- Controlled restart performed
- NIBP analyzer used
- Repeat measurements completed
- Indicator lights or other faults noted
- Unusual sounds noted
- Unusual heat or smell noted
- Final device status documented
Final Thought
Reliable NIBP troubleshooting starts with patient safety and the external pneumatic path: cuff, sizing, application, hose, connectors, motion, and settings. Controlled substitution and repeatable verification help distinguish accessory problems from internal failure. When known-good accessories and controlled testing still produce failure, removing the device from service and escalating for qualified repair is the correct action. Clear CCR documentation preserves what was reported, what was found, and why the final disposition was appropriate.
That is successful troubleshooting.