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What This Guide Helps With
This guide assists Clinical Engineering in troubleshooting Drager Primus ventilators when the bellows fails to cycle correctly. A bellows that does not rise and fall properly can indicate airflow obstruction, gas delivery issues, or mechanical problems, potentially compromising patient ventilation. Most causes are external or easily verifiable before considering internal repair.
Step-by-Step Troubleshooting
Verify Power and Initialization
- Confirm the ventilator is plugged into a working outlet and the main power switch is on.
- Ensure battery backup is charged.
- Why: The bellows will not cycle if the unit is not powered correctly.
Check Gas Supply Lines
- Verify that both oxygen and air sources are connected and turned on.
- Check for kinks, leaks, or loose fittings in the supply lines.
- Why: Insufficient gas flow prevents proper bellows inflation.
Inspect the Bellows Assembly and Circuit
- Ensure the bellows is seated correctly in the ventilator.
- Confirm the breathing circuit is connected and free of obstructions.
- Look for moisture or condensation that may impede movement.
- Why: Improper placement or obstruction can block bellows movement.
Review Ventilator Settings
- Check tidal volume, respiratory rate, and inspiratory/expiratory pressures.
- Ensure settings are within safe operational ranges.
- Why: Extreme settings can prevent the bellows from cycling normally.
Check Pressure Relief Valves and Filters
- Inspect the exhalation valve and any inline filters for blockages.
- Replace if visibly obstructed or soiled.
- Why: Obstructed valves create resistance, preventing proper cycling.
Perform a Pre-Use Self-Test
- Run the built-in system check.
- Observe whether errors are generated.
- Why: This can identify internal sensor or mechanical failures.
If the Problem Persists
External checks have been completed and no issues are found. Bellows still fails to cycle correctly.
Action:
- Remove the ventilator from service.
- Label “Out of Service.”
- Send for vendor repair or bench evaluation.
- Clinical Engineering should avoid further disassembly to protect patient safety and warranty compliance.
Clinical Use Tip
- Never troubleshoot the bellows on a patient-connected ventilator.
- Move the patient to another ventilator before attempting any troubleshooting.
- Always verify all gas connections and circuit integrity before returning the ventilator to clinical use.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
“User reports the bellows does not rise or fall properly during ventilation.”
Cause
What was observed during troubleshooting.
Example:
“Observed that gas supply lines were connected but the exhalation valve had minor obstruction preventing normal bellows cycling.”
Resolution
What action was taken.
Example:
“Cleared obstruction from exhalation valve and verified bellows cycled correctly during pre-use self-test. If unresolved, ventilator removed from service and sent for vendor evaluation.”
Helpful Details to Include
- Outlet tested: Yes
- Gas supply verified: Yes
- Breathing circuit inspected: Yes
- Bellows position: Correct
- Exhalation valve and filters inspected: Yes
- Error messages during self-test: None / Record if present
- Final device status: Operational / Out of Service if unresolved
Final Thought
Always prioritize patient safety over troubleshooting. Start with logical, external checks before assuming internal failure. Accurate documentation supports efficient repair and prevents repeated downtime.
That is successful troubleshooting.