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What This Guide Helps With
Troubleshooting a missing CO₂ waveform or unrecognized analyzer caused by module seating, sensor connections, airway-adapter contamination, warm-up, calibration, or configuration issues.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not troubleshoot unreliable CO₂ monitoring while the Servo-i is actively supporting a patient when capnography is clinically required.
- Notify respiratory therapy and the clinical team.
- Transfer CO₂ monitoring to another verified monitor or ventilator.
- Move the patient to another ventilator when the Servo-i cannot be safely evaluated without interrupting ventilation.
- Confirm that ventilation and independent patient monitoring remain available.
Expected outcome: The patient is safely supported without relying on missing or unreliable Servo-i capnography.
Continue Clinical Engineering troubleshooting only after the device can be evaluated safely.
2. Confirm the Exact Failure
Determine whether:
- The CO₂ module is not displayed or recognized.
- The module is recognized, but no waveform appears.
- An etCO₂ value appears without a normal capnogram.
- The display shows a CO₂ airway-adapter or calibration message.
- The problem is continuous or intermittent.
Record all displayed messages before restarting or removing components.
Expected outcome: The failure is narrowed to module recognition, sensor detection, airway-adapter measurement, or calibration.
3. Verify That Only One CO₂ Module Is Installed
Inspect the Servo-i module compartment and confirm that only one CO₂ analyzer module is installed.
The Servo-i can handle only one CO₂ module at a time. Installing two modules can prevent normal recognition or operation.
Remove any duplicate module and restart the ventilator in accordance with facility procedures.
Expected outcome: One properly installed CO₂ module is present and recognized.
If recognition returns, complete an operational check and stop.
4. Reseat the CO₂ Module
Power the ventilator down after confirming it is removed from patient use.
- Remove the CO₂ module.
- Inspect the module housing, guides, and connector area for debris, liquid intrusion, bent contacts, or physical damage.
- Reinsert the module fully and evenly.
- Confirm that it locks securely into position.
- Restart the Servo-i and observe whether the module appears on the display.
Do not force the module or probe connector contacts.
Expected outcome: The Servo-i detects the installed CO₂ module during startup.
If the module remains unrecognized, test with a known-good compatible module when available.
5. Inspect the Capnostat Sensor and Cable
Check the external sensor assembly for:
- A loose connection at the CO₂ module
- Damaged or bent connector pins
- Cuts, crushing, or strain damage along the cable
- Fluid contamination
- Cracked sensor housing
- Evidence of excessive heat
Disconnect and reconnect the sensor cable securely.
Expected outcome: The capnostat sensor is fully connected and free of visible damage.
If a known-good compatible sensor restores operation, remove the failed sensor from service.
6. Allow the Sensor to Warm Up
After connecting the module and capnostat sensor, allow adequate warm-up time before evaluating accuracy or performing calibration.
The manufacturer notes that values displayed during sensor warm-up have reduced accuracy and that the sensor should be warm before calibration.
Expected outcome: The warm-up indication clears and the analyzer becomes ready for measurement.
If the waveform appears after warm-up, verify operation and stop.
7. Inspect the Airway Adapter
Remove the airway adapter from clinical use and inspect it under good lighting.
Check for:
- Condensation
- Mucus or secretion contamination
- Nebulized medication residue
- Cracked or clouded optical windows
- Incorrect sensor engagement
- An adapter that is not fully inserted into the sensor
If the Servo-i displays Check CO₂ airway adapter, confirm that the adapter is completely inserted and wipe or replace it as appropriate.
Use only an approved compatible airway adapter with the capnostat sensor.
Expected outcome: The adapter windows are clean, dry, unobstructed, and correctly seated.
If replacing the adapter restores the capnogram, document the contaminated or defective adapter and stop.
8. Verify Sensor and Adapter Orientation
Confirm that the capnostat sensor and airway-adapter windows are positioned vertically when connected to the test circuit.
Vertical placement helps reduce optical interference caused by contamination collecting on the adapter windows.
Expected outcome: The sensor is correctly positioned and produces a stable waveform during simulated ventilation.
9. Check for Nebulizer or Circuit Interference
Determine whether the reported failure occurred during nebulizer use or when excessive condensation was present.
Nebulizer operation can affect CO₂ readings, and moisture or deposits can obstruct the adapter’s optical path.
For bench testing:
- Use a clean, dry circuit.
- Remove unnecessary aerosol-generating accessories.
- Replace contaminated adapters.
- Verify the capnogram using an approved test method.
Expected outcome: The waveform returns when optical interference and moisture are eliminated.
10. Verify CO₂ Display and Monitoring Configuration
Confirm that:
- CO₂ monitoring is enabled.
- The CO₂ waveform is selected for display.
- The waveform is not hidden by the current screen layout.
- etCO₂ alarm limits and units are appropriately configured.
- The correct patient category and ventilation configuration are selected.
The Servo-i can display a CO₂ waveform, end-tidal CO₂, CO₂ minute elimination, and CO₂ tidal elimination when the analyzer is operating.
Expected outcome: The CO₂ parameter and waveform are visible in the configured display.
11. Perform the Approved CO₂ Verification or Calibration
Only perform calibration after the sensor has warmed and according to the approved Getinge procedure for the installed Servo-i software and analyzer version.
For systems using the documented CAPNOSTAT 5 procedure, the Servo-i provides a CO₂ calibration menu with a verification function using an unconnected airway adapter containing room air.
Do not perform improvised calibration or use unapproved calibration gases.
Expected outcome: The analyzer passes verification or calibration and produces a stable capnogram.
If calibration repeatedly fails, stop troubleshooting and escalate the device.
12. Substitute Known-Good External Components
When available, test one component at a time using compatible, verified parts:
- Airway adapter
- Capnostat sensor and cable
- CO₂ module
Do not swap several components simultaneously because this prevents accurate identification of the cause.
Expected outcome: The defective external component is isolated.
After replacing the failed component, complete the manufacturer-approved functional and performance verification before returning the ventilator to service.
If the Problem Persists
If the Servo-i still does not recognize the CO₂ module, repeatedly loses communication, fails calibration, or produces no capnogram with known-good accessories, common external causes have been ruled out.
The problem may involve the CO₂ module, module connector, internal communication path, power supply, software configuration, or another internal assembly.
The ventilator should be:
- Removed from service
- Labeled Out of Service
- Sent for qualified bench evaluation or Getinge-authorized repair
- Subjected to complete functional and performance testing after repair
Do not perform internal board-level repairs without appropriate training, documentation, test equipment, and authorization. Knowing when to stop is proper troubleshooting.
Clinical Use Tip
Never troubleshoot the CO₂ module by repeatedly disconnecting the sensor or airway adapter while capnography is required for an active patient. Establish alternate verified ventilation and CO₂ monitoring first.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Respiratory therapy reported that the Servo-i did not display a CO₂ waveform and intermittently showed the CO₂ module as unavailable."
Cause
What was observed during troubleshooting.
Example:
"Found the capnostat airway adapter contaminated with condensation and not fully seated in the sensor."
Resolution
What action was taken.
Example:
"Replaced the airway adapter, reseated the capnostat sensor, allowed warm-up, and verified a stable capnogram and etCO₂ measurement during functional testing."
Helpful Details to Include (If Known)
- CO₂ module recognized at startup
- Exact displayed message
- Sensor warm-up completed
- Module reseated
- Connector condition inspected
- Known-good sensor tested
- Known-good module tested
- Airway adapter replaced
- Condensation or contamination found
- Nebulizer use reported
- Calibration or verification result
- Capnogram stability
- Final device status
Final Thought
CO₂ failures should be approached by protecting the patient first, then checking module seating, sensor connections, airway-adapter condition, warm-up, configuration, and calibration. Logical component substitution and accurate CCR documentation prevent unnecessary internal repair and support a safe return to clinical use.
That is successful troubleshooting.