Drager Apollo

Asset Type

Anesthesia Machine

Manufacturer

Drager

Model

Apollo

What This Guide Helps With

This guide helps troubleshoot a PRESSURE LIMITING alarm on a Drager Apollo anesthesia machine. This alarm indicates the ventilator is operating with pressure limitation. Possible causes include ventilation settings, a kinked or stenosed tube, restricted breathing hoses, or a soiled microbial filter on the inspiration side.

The main concern is that pressure limitation may prevent the ventilator from delivering the expected breath. Treat this as a ventilation safety issue first, then work through external causes before assuming internal machine failure.

Step-by-Step Troubleshooting

Ensure Patient Safety First

• Confirm whether the patient is currently connected to the Apollo.
• Do not perform extended troubleshooting while the anesthesia machine is actively supporting a patient unless anesthesia staff determine it is safe.
• If ventilation is unstable, the alarm continues, or expected ventilation is not being delivered, notify anesthesia immediately.
• Have clinical staff ventilate the patient using an alternate method if needed.
• Remove the anesthesia machine from patient use if the alarm cannot be corrected quickly and safely.

The expected outcome is that patient ventilation is maintained without relying on a machine with an unresolved pressure limitation condition.

Verify the Reported Alarm and Behavior

• Confirm the displayed alarm is exactly: PRESSURE LIMITING.
• Ask staff when the alarm occurs, such as during mechanical ventilation, during inspiration, after a setting change, or only with certain circuits or filters.
• Ask whether staff observed low delivered tidal volume, high airway pressure, poor chest rise, or the ventilator not reaching expected volume.
• Determine whether the alarm started after changing the breathing circuit, microbial filter, patient tube, HME/filter, or ventilation settings.

The expected outcome is that the alarm and trigger conditions are clearly understood before parts or settings are changed.

Check the Ventilation Settings

• Have anesthesia review the active ventilation mode and patient-specific settings.
• Check whether the pressure limit, peak pressure limit, inspiratory pressure, tidal volume, PEEP, and flow settings are appropriate for the selected mode.
• Verify whether the alarm began after a recent setting adjustment.
• Do not change clinical ventilation settings unless directed by qualified anesthesia staff.

If the alarm resolves after anesthesia corrects an improper setting, document the setting-related cause and verify normal operation before return to use.

Inspect the Breathing Circuit and Patient Tubing

• Check the breathing hoses from the machine to the patient connection.
• Look for kinked tubing, crushed tubing, occluded tubing, twisted hoses, water accumulation, incorrect circuit setup, or restriction near the Y-piece.
• Check for a kinked or stenosed patient tube if clinical staff report poor ventilation or high pressure.
• Straighten or replace affected tubing if needed.

The expected outcome is that the tubing is open, correctly connected, and free of restriction.

Check the Inspiratory-Side Microbial Filter

• Inspect the microbial filter on the inspiration side.
• Check for soiling, moisture, secretions, visible restriction, high resistance, incorrect placement, or backwards installation if the filter is directional.
• Ask whether the filter was recently changed before the alarm started.
• Replace the filter if it appears dirty, wet, clogged, or questionable.

A soiled or saturated microbial filter can increase resistance and cause the ventilator to operate under pressure limitation.

Check for Obstruction at the Patient Connection

• With clinical staff involved, verify the patient connection and airway interface are not restricted.
• Check for a bite block issue, kinked endotracheal tube, stenosed tube, obstructed connector, HME/filter obstruction, secretions, moisture buildup, or circuit compression near the patient.
• Correct or replace restricted external components according to clinical direction and facility policy.

The expected outcome is that there is no downstream restriction between the machine and the patient airway.

Check the Breathing System Setup

• Inspect the breathing system for correct assembly.
• Confirm inspiratory and expiratory hoses are properly connected.
• Verify that no ports are capped incorrectly and no accessory is installed in the wrong location.
• Confirm filters, adapters, and patient connections are appropriate for the circuit.
• Check that the APL/manual ventilation setup is not causing confusion with ventilator operation.
• Confirm scavenging and breathing system components are not physically obstructed.

Incorrect circuit assembly or accessory placement can create resistance that appears as a ventilator pressure limitation problem.

Isolate Accessory-Related Causes

• If safe and allowed by local policy, replace questionable external accessories one at a time.
• Check by substitution: breathing circuit, inspiratory microbial filter, HME/filter, patient connector, flow-related adapters, and any accessory near the patient connection.
• After each change, retest ventilation using the appropriate clinical or test setup.
• Do not use a patient as the test load for extended troubleshooting.

The expected outcome is that the alarm clears after the restricted or incorrect accessory is replaced.

Perform a Basic Machine Check After Corrections

• After correcting tubing, filter, setting, or setup issues, run the appropriate anesthesia machine checkout according to facility procedure.
• Verify there is no active PRESSURE LIMITING alarm.
• Confirm the ventilator cycles normally.
• Verify measured pressure behaves as expected.
• Confirm delivered volume or pressure is appropriate for the selected mode.
• Confirm no new alarms appear.
• Confirm the circuit passes required leak and compliance checks.

Clearing the alarm is not enough. The machine should be verified under a controlled checkout before being returned to patient care.

If the Problem Persists

If the PRESSURE LIMITING alarm continues after ventilation settings, tubing, hoses, patient connection, breathing circuit setup, and microbial filters have been checked, external and common causes have been ruled out.

A persistent pressure limitation condition may indicate an internal ventilator control, pressure sensing, flow delivery, valve, or breathing system issue.

• Remove the Apollo from service.
• Label it Out of Service.
• Send it for bench evaluation or qualified anesthesia service repair.
• Do not return the machine to patient use until the pressure limiting issue is corrected and the machine passes the required checkout.

Knowing when to stop is proper troubleshooting.

Clinical Use Tip

Never troubleshoot on an active patient when the troubleshooting could interrupt ventilation, pressure delivery, or patient monitoring. Move the patient to a backup anesthesia machine or alternate ventilation method first when the alarm cannot be corrected immediately and safely.

Work Order Documentation (CCR Method)

CCR = Complaint, Cause, Resolution

Complaint

What was reported by the clinical staff.

Example:
"Drager Apollo reported PRESSURE LIMITING alarm during ventilation. Staff reported ventilator was operating with pressure limitation and requested Clinical Engineering evaluation."

Cause

What was observed during troubleshooting.

Example:
"Inspiratory microbial filter was found soiled and restricted, causing increased inspiratory resistance and repeated PRESSURE LIMITING alarm."

Resolution

What action was taken.

Example:
"Removed device from patient use for inspection. Checked ventilation settings, breathing hoses, patient tubing, breathing circuit setup, and inspiratory microbial filter. Replaced restricted microbial filter. Verified alarm cleared and machine passed required checkout before return to service."

Helpful Details to Include (If Known)

• Alarm behavior
• Accessories swapped
• Power behavior
• Environmental factors
• Indicator lights
• Final device status

Final Thought

The PRESSURE LIMITING alarm should be approached as a ventilation safety issue first. Start with the patient, then verify the alarm, then check settings, tubing, hoses, filters, and circuit setup before assuming internal failure. If the alarm persists after external causes are ruled out, remove the machine from service and escalate for proper evaluation. Clear documentation protects the patient, the clinical team, and the equipment history.

That is successful troubleshooting.