Drager Atlan A350

Flow Sensor Calibration Failure

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Asset Type

Anesthesia Machine

Manufacturer

Drager

Model

Atlan A350

What This Guide Helps With

Flow sensor calibration fails because of sensor contamination, moisture, incorrect installation, breathing-system leaks, connection problems, or a service-level measurement fault.

Step-by-Step Troubleshooting

1. Protect the Patient

Do not troubleshoot an unreliable flow-measurement system while a patient depends on the anesthesia machine. Place the patient on an appropriate verified alternative if accurate ventilation monitoring or delivery is in question. Expected outcome: Patient ventilation and monitoring remain reliable while the affected machine is evaluated separately.

2. Confirm the Calibration Failure

Record the exact displayed message and determine whether the failure occurs during startup, system test, calibration, or clinical preparation. Repeat the approved calibration only under the correct non-patient test conditions. Expected outcome: The failure is confirmed and associated with a specific test condition. If calibration succeeds normally on repeat, complete the system test before returning the unit to service.

3. Inspect Flow Sensor Installation

Check the externally accessible flow sensor or sensors for proper orientation, complete seating, and secure connection according to the normal equipment setup. Do not force the sensor or alter internal connections. Expected outcome: The sensor is correctly installed and fully seated. If reseating resolves the calibration failure, repeat the applicable system test and proceed to final verification.

4. Inspect for Moisture or Contamination

Examine accessible sensor surfaces and adjacent breathing-system components for moisture, condensation, visible contamination, or debris that may interfere with measurement. Handle and clean reusable components only according to approved manufacturer and facility procedures. Expected outcome: The measurement path is clean and dry. If removing an approved external source of moisture or contamination permits successful calibration, repeat the test before release.

5. Check the Breathing System for Leaks

Inspect circuit connections, bags, filters, adapters, sampling connections, and externally accessible breathing-system components for leakage or incomplete assembly. A leak can interfere with calibration even when the sensor itself is functional. Expected outcome: The breathing system is intact and correctly assembled. If correcting a leak allows calibration to pass, complete the full system test.

6. Substitute a Known-Good Compatible Sensor When Appropriate

If facility inventory and manufacturer procedures permit, substitute a known-good compatible flow sensor or approved sensor assembly. Do not interchange components of uncertain compatibility. Expected outcome: If the known-good sensor calibrates successfully, the original sensor or its external condition is isolated as the cause. Replace the failed approved component and verify the system.

7. Inspect External Sensor Connections

Check accessible electrical or pneumatic sensor connections for incomplete seating, bent or damaged contacts, contamination, or cable damage. Do not open internal assemblies to trace sensor circuitry. Expected outcome: External sensor connections are intact and secure. If restoring a connection resolves the failure, repeat calibration and system testing.

8. Repeat Calibration and System Testing

With the machine assembled correctly and the breathing system in the proper test configuration, repeat the approved calibration and complete system test. Expected outcome: Flow sensor calibration completes successfully and the machine passes the associated system checks. If so, troubleshooting can stop after final verification.

9. Verify Flow and Volume Measurement

Use approved anesthesia or ventilator test equipment to verify that displayed flow and volume measurements respond appropriately during controlled ventilation. Expected outcome: Flow and volume measurement are stable and consistent with independent testing, supporting safe return to service.

10. Escalate Repeated Calibration Failure

If a known-good properly installed sensor also fails calibration or measurement remains unreliable, stop external troubleshooting and remove the machine from service. Expected outcome: A persistent measurement-system fault receives appropriate service-level evaluation.

If the Problem Persists

Sensor installation, contamination, moisture, breathing-system leaks, known-good substitution, and external connections have been evaluated. Remaining possibilities may involve an internal sensor interface, calibration circuit, measurement pathway, electronics, pneumatic condition, or other service-level fault. The device should be:

After service, complete the applicable calibration, system test, ventilation measurements, alarm verification, and return-to-service checks. Knowing when to stop external troubleshooting is proper troubleshooting.

Clinical Use Tip

Do not rely on displayed ventilation measurements when flow-sensor calibration cannot be completed successfully.

Work Order Documentation (CCR Method)

CCR = Complaint, Cause, Resolution

Complaint

What was reported by the clinical staff.

Example:
"Anesthesia staff reported the Drager Atlan A350 would not complete flow sensor calibration during the pre-use check."

Cause

What was observed during troubleshooting.

Example:
"Clinical Engineering found moisture on the externally accessible flow sensor assembly."

Resolution

What action was taken.

Example:
"Clinical Engineering addressed the moisture condition using approved handling procedures, reinstalled the sensor, completed calibration successfully, and verified flow and volume measurement before return to service."

Helpful Details to Include (If Known)

Final Thought

Accurate flow measurement supports both ventilation delivery and monitoring. Inspect external causes first, verify calibration rather than assuming sensor failure, and escalate any persistent or unreliable measurement condition. That is successful troubleshooting.

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