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What This Guide Helps With
This guide helps troubleshoot the AC POWER LOSS Operating on battery alarm on the Puritan Bennett 840 Ventilator. This condition means AC input power is not available and the ventilator is running on battery, creating a risk of shutdown if external power is not restored promptly.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- Immediately confirm the patient is being ventilated adequately.
- Prepare backup ventilation such as a manual resuscitator or alternate ventilator if needed.
- Do not allow troubleshooting steps to interrupt active patient support.
Verify the Reported Alarm and Behavior
- Confirm the AC POWER LOSS alarm is active on the display.
- Check whether the ventilator indicates battery operation.
- Observe whether the AC power indicator is off.
- Listen for the audible alarm and note any battery runtime indication if displayed.
Check AC Power Source
- Verify the outlet supplying the ventilator is active.
- Plug in a known-good device to confirm power is present.
- Confirm the ventilator is connected to the correct hospital-grade or emergency power outlet if applicable.
Inspect Power Cord and Connections
- Ensure the AC power cord is firmly seated at both the wall outlet and the ventilator.
- Inspect the cord for cuts, fraying, bent contacts, or loose connectors.
- Reseat the cord securely and watch for return of AC power indication.
Check Power Strip or Extension Use
- If a power strip or extension is being used, bypass it and plug the ventilator directly into the wall outlet.
- Verify any intermediate device is powered on and functioning properly.
- Do not continue relying on questionable external power accessories.
Verify Facility Power Availability
- Check nearby equipment to see whether they also lost power.
- Confirm whether the outlet is on emergency power if required.
- Ask staff whether there was a recent room or unit power interruption.
Observe for AC Power Recovery
- After correcting the external power issue, confirm the AC power indicator turns back on.
- Verify the ventilator transitions from battery operation back to AC power.
- Ensure the alarm clears automatically once normal power is restored.
If the Problem Persists
If AC power is confirmed at the outlet, the power cord is secure, and any external power accessories have been ruled out, but the ventilator remains on battery, external causes have been ruled out.
Remove the device from service, label it Out of Service, and send it for repair or bench evaluation. Persistent AC power loss under these conditions strongly suggests an internal power supply problem.
Clinical Use Tip
Never troubleshoot on an active patient. Move the patient to a backup device first. Always connect ventilators to emergency power outlets during clinical use and do not rely on battery power for ongoing ventilation support.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Ventilator alarmed AC POWER LOSS and switched to battery operation during patient use."
Cause
What was observed during troubleshooting.
Example:
"AC outlet had no available power or the power cord connection at the wall was loose, preventing AC input to the ventilator."
Resolution
What action was taken.
Example:
"Reseated the power cord, confirmed outlet functionality, verified return to AC power, and confirmed the alarm cleared. Device returned to service after normal operation was verified."
Helpful Details to Include (If Known)
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
Power-related alarms on a ventilator should always be treated as urgent because ongoing patient support depends on reliable power. Start with simple external checks such as the outlet, cord, and intermediate power devices, but escalate quickly if AC power does not return. Protect the patient first, troubleshoot logically, document clearly, and remove the device from service when internal failure is suspected.
That is successful troubleshooting.