GE Healthcare Aisys CS2

Asset Type

Anesthesia Machine

Manufacturer

GE Healthcare

Model

Aisys CS2

What This Guide Helps With

Troubleshooting failed flow-sensor calibration caused by moisture, contamination, incorrect installation, damaged sensors, breathing-circuit connections, or unsuitable calibration conditions.

Step-by-Step Troubleshooting

1. Ensure Patient Safety First

Do not remove, clean, exchange, or calibrate flow sensors while the Aisys CS2 is supporting an active patient.

If the calibration failure occurs during clinical use:

• Notify the anesthesia provider immediately.
• Confirm whether ventilation, airway pressure, and volume measurements remain clinically reliable.
• Maintain approved independent patient monitoring.
• Move the patient to another verified anesthesia machine or approved ventilation method when measurement accuracy is uncertain.

Expected outcome: Patient care no longer depends on equipment with questionable flow or volume measurement.

Continue troubleshooting only after the machine is safely removed from patient use.

2. Confirm the Exact Failure Condition

Record the complete displayed message and determine whether the failure involves:

• The inspiratory flow sensor
• The expiratory flow sensor
• Both flow sensors
• Calibration that will not begin
• Calibration that begins but does not complete
• Unstable volume measurements following calibration

Review the alarm and error history for related ventilation, sensor, or breathing-system messages.

Expected outcome: The affected sensor and failure pattern are clearly identified.

3. Place the Machine in the Correct Calibration Condition

Confirm that:

• The machine is not connected to a patient.
• The breathing system is assembled correctly.
• No one is squeezing the reservoir bag or disturbing the circuit.
• Gas flow through the breathing system is stable.
• The machine has completed startup and is ready for checkout.

Air movement or pressure changes during calibration can prevent the system from establishing a reliable zero-flow reference.

Expected outcome: The machine is stable and ready for an undisturbed calibration attempt.

4. Inspect the Breathing Circuit and Connections

Check the inspiratory and expiratory circuit connections for:

• Loose or partially seated hoses
• Incorrect hose placement
• Kinked or compressed tubing
• Obstructions
• Excessive condensate
• Damaged connectors
• Accessories installed in an unusual configuration

Correct any visible issue and repeat the calibration.

Expected outcome: The breathing circuit is correctly connected and free of external restrictions.

If calibration completes successfully, perform the required system checkout and stop troubleshooting.

5. Inspect the Flow Sensors

Remove the flow sensors only after confirming the machine is safely out of service.

Inspect each sensor for:

• Moisture or condensation
• Secretions or visible contamination
• Cracks or physical damage
• Bent, broken, or contaminated contacts
• Damaged sealing surfaces
• Incorrect orientation
• Incomplete seating

The Aisys CS2 uses respiratory flow measurement as part of its ventilation and monitoring functions, making correct installation and sensor condition essential.

Expected outcome: Both sensors are clean, dry, undamaged, correctly oriented, and fully seated.

6. Allow Wet Sensors to Dry

If moisture is present:

• Remove the affected sensor according to facility procedures.
• Allow it to dry completely.
• Do not insert objects into the sensor openings.
• Do not use unapproved compressed air, heat, or cleaning chemicals.
• Follow the approved cleaning and disinfection instructions for the sensor type.

Reinstall the dry sensor securely and repeat calibration.

Expected outcome: Calibration completes after moisture-related interference is removed.

If calibration passes, complete the system checkout before returning the machine to service.

7. Reseat Both Flow Sensors

Remove and reinstall both sensors, even when only one side is identified by the displayed message.

Confirm that:

• Each sensor is installed in the correct location.
• The direction and orientation are correct.
• The sensor is fully inserted.
• No cable, tubing, or breathing-system component prevents complete seating.
• The associated seals and connectors appear intact.

Repeat calibration without touching the breathing system.

Expected outcome: Calibration succeeds after correcting a poor or incomplete sensor connection.

8. Substitute a Known-Good Compatible Sensor

When permitted by facility policy, replace the suspected sensor with a clean, dry, known-good compatible sensor.

Repeat the calibration.

• If calibration succeeds, remove the original sensor from service for further evaluation or replacement.
• If the failure remains with the same sensor position, inspect the associated external connection and breathing-system assembly again.
• If both sensors fail despite known-good substitutions, suspect a machine-side sensing or communication problem.

Expected outcome: Sensor substitution identifies whether the failure follows the removable sensor.

9. Check for Breathing-System Moisture or Contamination

Inspect accessible breathing-system components for moisture or contamination that could affect airflow during calibration, including:

• Sensor housings
• Inspiratory and expiratory ports
• Circuit connections
• Condensate accumulation points
• Reusable breathing-system components

Correct visible external conditions using approved procedures.

Expected outcome: The breathing system is clean, dry, correctly assembled, and free of conditions that could disturb sensor calibration.

10. Restart the System

With the machine removed from patient use:

• Turn the Aisys CS2 off using the normal shutdown process.
• Allow the shutdown to complete.
• Verify that external power is stable.
• Restart the machine.
• Allow startup initialization to finish.
• Repeat the flow-sensor calibration.

A controlled restart may clear a temporary initialization or sensor-recognition condition.

Expected outcome: The sensors are recognized and calibration completes normally.

11. Perform the Complete System Checkout

After a successful calibration, perform the manufacturer-required pre-use or system checkout.

Verify:

• Flow-sensor calibration passes.
• Leak testing passes.
• Ventilator operation is normal.
• Inspired and expired volume readings are stable.
• Airway-pressure measurements are reasonable.
• No flow-sensor or ventilation alarms return.
• The machine operates correctly using an approved test lung.

Expected outcome: The Aisys CS2 passes all required checks and demonstrates reliable ventilation and monitoring.

Do not return the machine to clinical use based only on a single successful calibration.

If the Problem Persists

If calibration continues to fail after the circuit, moisture, sensor installation, sensor condition, and known-good sensor substitution have been checked, common external causes have been ruled out.

The fault may involve an internal sensor interface, wiring connection, signal-processing circuit, breathing-system component, or ventilator electronics. GE identifies the Aisys CS2 technical reference material as the appropriate source for diagnosis, calibration, repair, and checkout procedures.

The device should be:

• Removed from service
• Labeled Out of Service
• Sent for qualified bench evaluation or authorized repair
• Evaluated using approved GE Healthcare service documentation and test equipment

Knowing when to stop external troubleshooting and escalate is proper Clinical Engineering practice.

Clinical Use Tip

Never attempt flow-sensor calibration while the anesthesia machine is actively ventilating a patient. Establish alternate ventilation and monitoring before disturbing any breathing-system component.

Work Order Documentation (CCR Method)

CCR = Complaint, Cause, Resolution

Complaint

What was reported by the clinical staff.

Example:
"Anesthesia staff reported that the GE Healthcare Aisys CS2 displayed a flow-sensor calibration failure during the pre-use checkout."

Cause

What was observed during troubleshooting.

Example:
"The expiratory flow sensor contained visible condensation and did not pass calibration until it was removed, dried, and correctly reinstalled."

Resolution

What action was taken.

Example:
"Dried and reseated the expiratory flow sensor, completed flow-sensor calibration, performed the full system checkout with a test lung, and returned the machine to service after all tests passed."

Helpful Details to Include (If Known)

• Complete displayed calibration message recorded
• Inspiratory, expiratory, or both sensors affected
• Moisture or contamination observed
• Flow sensors removed and reseated
• Known-good sensor substitution performed
• Breathing-circuit connections inspected
• Calibration repeated after restart
• Leak test result documented
• Test-lung ventilation verified
• Volume and pressure readings confirmed stable
• Related alarms or error codes recorded
• Final device status documented

Final Thought

Flow-sensor calibration failures should be approached by protecting the patient first, then checking calibration conditions, circuit assembly, moisture, sensor seating, and removable components. Escalate when external causes are exhausted, and document exactly what was found and verified.

That is successful troubleshooting.