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Manufacturer
Model
What This Guide Helps With
Addresses unstable fresh-gas delivery or incorrect oxygen ratio caused by gas supplies, controls, connections, settings, or external measurement problems.
Step-by-Step Troubleshooting
1. Protect the Patient and Maintain Safe Gas Delivery
Do not troubleshoot unstable oxygen or fresh-gas delivery while a patient depends on the machine. Move the patient to another verified anesthesia or ventilation system as clinically appropriate.
If gas composition cannot be trusted, remove the Atlan A100 from clinical use.
Expected outcome: Patient care continues using a verified source and the affected machine is available for safe technical evaluation.
2. Confirm the Reported Condition
Record the selected gas settings, displayed values, gas sources in use, and whether the problem occurs continuously or only at certain settings.
Determine whether the concern is unstable total flow, an unexpected oxygen concentration, or disagreement between set and measured values.
Expected outcome: The exact symptom is reproducible and clearly defined. If operation is stable during controlled testing, continue verification before returning the unit to service.
3. Verify Pipeline and Cylinder Gas Sources
Confirm the intended pipeline gases are connected to the correct indexed connections and that available supply indicators appear normal. Inspect hoses for kinks, damage, loose fittings, or incorrect routing.
Where appropriate, compare operation using an alternate approved gas source to help distinguish the machine from facility infrastructure.
Expected outcome: Correct gases are connected and supplies remain stable. If changing to a verified source corrects the condition, investigate the original gas source or infrastructure rather than the machine.
4. Verify Mixer Controls and Selected Settings
Check the mechanical gas-mixer controls for normal movement and verify that the selected carrier gas, oxygen setting, and total fresh-gas flow are appropriate for the intended test.
Ensure no control is partially positioned or physically obstructed.
Expected outcome: Controls move normally and the intended settings remain stable. If correcting an external control position restores expected delivery, troubleshooting can stop after verification.
5. Inspect Gas Connections and External Accessories
Inspect accessible gas hoses, connectors, auxiliary gas connections, vaporizers, breathing-system connections, and other externally attached equipment that may affect gas flow.
Temporarily remove nonessential external accessories if allowed by normal operating configuration.
Expected outcome: No loose connection, unintended flow path, or accessory-related disturbance remains.
6. Compare With Independent Gas Measurement
Using approved anesthesia gas-analysis equipment, compare delivered oxygen concentration and fresh-gas behavior with the machine's displayed values.
Confirm the test analyzer, sampling line, water trap, and calibration status are reliable before interpreting disagreement as a machine fault.
Expected outcome: Independent measurement agrees reasonably with expected machine operation. If the discrepancy follows the external analyzer or sampling setup, correct that equipment and stop troubleshooting the anesthesia machine.
7. Check for Environmental or Supply Instability
Observe whether the problem coincides with changes in pipeline source, cylinder switchover, high facility demand, or other environmental conditions.
If possible, test in a controlled bench configuration using verified supplies.
Expected outcome: Gas delivery remains stable when supplied from a known-good source. Instability isolated to the infrastructure should be escalated to the responsible facilities or gas-system team.
8. Restart and Recheck Gas Delivery
After external causes are corrected, restart the machine normally and recheck multiple clinically relevant gas-mixer settings using approved test equipment.
Do not enter restricted calibration or service functions.
Expected outcome: Gas flow and oxygen delivery remain stable and respond predictably to control changes. If so, proceed to final verification.
9. Perform Final Functional Verification
Complete the required system test and verify oxygen monitoring, gas delivery, alarms, and ventilation using approved test equipment before return to service.
Expected outcome: The machine passes required functional checks and gas delivery is stable across the tested range.
10. Escalate Persistent Mixer Instability
If gas sources, hoses, control positions, accessories, and independent measurements are verified but flow or oxygen ratio remains incorrect, remove the machine from service.
Expected outcome: The unresolved problem is referred for qualified evaluation of internal gas-mixing, regulation, sensing, or control systems.
If the Problem Persists
External gas supplies, connections, settings, accessories, and measurement equipment have been ruled out. Persistent instability may involve internal gas regulation, mixer mechanics, sensing, or control components requiring authorized service-level evaluation.
The device should be:
- Removed from service.
- Labeled Out of Service.
- Sent for repair or bench evaluation.
- Evaluated using appropriate Drager documentation and approved gas-analysis equipment.
- Repaired or configured only by qualified personnel.
- Subjected to complete gas-delivery, ventilation, alarm, and system-test verification before return to service.
Stopping when delivered gas cannot be verified is proper troubleshooting.
Clinical Use Tip
Never rely on questionable oxygen delivery; provide anesthesia and ventilation with another verified system before troubleshooting the mixer.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"OR staff reported unstable fresh-gas flow and an unexpected oxygen concentration on the Drager Atlan A100."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found the oxygen pipeline hose connection was not fully secure, causing inconsistent supply to the machine."
Resolution
What action was taken.
Example:
"Clinical Engineering secured the oxygen connection, verified stable supply, confirmed gas delivery with approved test equipment, completed the system test, and returned the machine to service."
Helpful Details to Include (If Known)
- Gas sources connected
- Pipeline or cylinder operation
- Selected gas and flow settings
- Displayed oxygen value
- Independent analyzer result
- Hose and connector condition
- Whether alternate gas source was tested
- Whether instability affected one or multiple gases
- Results after correction
- Final system-test result
Final Thought
Unstable gas delivery must be treated as a patient-safety issue. Verify sources, controls, connections, and independent measurement before assuming internal mixer failure, and escalate whenever delivered gas cannot be confidently verified.
That is successful troubleshooting.