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What This Guide Helps With
This guide helps troubleshoot the PRESSURE RELIEF alarm on a Drager Apollo anesthesia machine. This alarm indicates that the internal pressure relief valve opened due to high system pressure. Possible external causes include APL valve setting, fresh-gas flow setting, breathing circuit restriction, bag path issue, scavenging restriction, or recent setup changes.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- High breathing system pressure can affect ventilation and patient safety.
- Remove the anesthesia machine from patient use if pressure is not immediately controlled or if ventilation is affected.
- Have anesthesia staff ventilate the patient using an alternate method if needed.
- Do not continue using the machine if the PRESSURE RELIEF alarm repeats or system pressure remains elevated.
- The goal is to prevent the patient from being exposed to excessive airway or breathing system pressure.
Verify the Reported Alarm and Behavior
- Confirm the exact alarm shown is PRESSURE RELIEF.
- Ask staff when the alarm occurred: during manual ventilation, mechanical ventilation, startup, fresh-gas adjustment, APL valve adjustment, or circuit connection.
- Observe the pressure gauge or displayed airway pressure only if it is safe to do so.
- Confirm whether the alarm is continuous, intermittent, or only appears during a specific mode or setup.
Check the APL Valve Setting
- Check the APL valve setting.
- If the alarm occurred during manual or bag ventilation, verify the APL valve was not set too high or fully closed.
- Have qualified anesthesia staff adjust the APL valve to an appropriate setting for clinical use.
- A closed or high APL setting can trap pressure in the breathing system and cause the internal pressure relief valve to open.
Check Fresh-Gas Flow Settings
- Review the fresh-gas flow settings.
- Confirm oxygen, air, and nitrous oxide flows are not set excessively high for the current ventilation setup.
- Have anesthesia staff adjust fresh-gas flow as clinically appropriate.
- Excessive fresh-gas flow can build pressure if the circuit, bag, APL valve, or scavenging path cannot release gas normally.
Check the Breathing Circuit for Obstruction or Kinks
- Inspect the breathing circuit, patient tubing, Y-piece, filters, HME, bag hose, and expiratory path.
- Look for kinked tubing, blocked filters, misconnected circuit parts, occluded patient connections, collapsed hoses, fluid buildup, or foreign material.
- Replace or correct any questionable external accessory according to facility procedure.
- A blocked or restricted breathing path can cause pressure to rise until the relief valve opens.
Check the Reservoir Bag and Bag Arm Connection
- Inspect the breathing bag and bag connection.
- Confirm the bag is not overfilled, blocked, twisted, or improperly attached.
- Check that the bag arm and bag hose are not obstructed.
- During manual ventilation, the bag and APL valve path are key pressure release points.
Check the Scavenging Setup
- Inspect the scavenging hose and waste gas path.
- Confirm the scavenging line is connected correctly and not kinked, crushed, blocked, or improperly restricted.
- Check for signs that the scavenging system is creating abnormal back pressure.
- A restricted scavenging path can contribute to elevated breathing system pressure.
Check for Accessory or Configuration Changes
- Ask whether any accessory was recently changed.
- Check for a new breathing circuit, new filter or HME, new CO2 absorber canister, recent cleaning or reassembly, or recent vaporizer, circuit, or bag setup change.
- Confirm all external accessories are installed correctly and appropriate for the machine setup.
- Pressure-related alarms often appear after a setup change, accessory swap, or circuit reconfiguration.
Run a Safe Functional Check
- After correcting any obvious issue, have qualified staff perform a safe checkout or leak/system test according to facility procedure.
- Confirm the alarm clears.
- Confirm ventilation pressure behaves normally.
- Confirm the APL valve responds normally.
- Confirm fresh-gas flow does not cause pressure buildup.
- Confirm the PRESSURE RELIEF alarm does not repeat.
If the Problem Persists
If the PRESSURE RELIEF alarm continues after checking the APL valve, fresh-gas flow, breathing circuit, bag path, external accessories, and scavenging setup, external and common causes have been ruled out.
A persistent PRESSURE RELIEF alarm may indicate a device-related pneumatic control problem, pressure sensing issue, valve issue, or internal restriction.
Remove the anesthesia machine from service.
Label it Out of Service.
Send it for repair or bench evaluation by qualified service personnel.
Clinical Use Tip
Never troubleshoot repeated pressure relief alarms on an active patient if ventilation safety is uncertain. Move the patient to a backup device or alternate ventilation method first, then evaluate the machine.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Drager Apollo anesthesia machine displayed PRESSURE RELIEF alarm during use. Staff reported internal pressure relief valve opened due to high system pressure."
Cause
What was observed during troubleshooting.
Example:
"APL valve setting and fresh-gas flow required verification. Breathing circuit, bag path, external accessories, and scavenging setup were checked for restriction or abnormal pressure buildup."
Resolution
What action was taken.
Example:
"Verified APL valve and fresh-gas settings, inspected breathing circuit and external gas paths, and confirmed alarm cleared with normal pressure behavior. Machine returned to service after functional check, or removed from service for further evaluation if alarm persisted."
Helpful Details to Include (If Known)
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
The PRESSURE RELIEF alarm should be treated as a real high-pressure safety condition until proven otherwise. Start with patient safety, confirm the alarm, check the APL valve and fresh-gas settings, then inspect the circuit and external gas paths. If the alarm continues after basic causes are ruled out, remove the machine from service and escalate for repair.
That is successful troubleshooting.