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Manufacturer
Model
What This Guide Helps With
Gas readings absent, inaccurate, or delayed due to blocked sampling line, water accumulation, or obstruction affecting gas module performance.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- If actively in use, confirm gas monitoring is available via another device or backup method.
- Do not rely on compromised gas readings.
Expected: Patient gas monitoring remains continuous.
Why it matters: Inaccurate gas readings can lead to unsafe anesthesia delivery.
Verify the Reported Issue
- Check for symptoms:
- No EtCO₂ or anesthetic agent readings
- Flat or erratic waveform
- Water visible in sampling line or water trap
Expected: Issue is reproducible and consistent with a flow obstruction.
Why it matters: Confirms this is a sampling issue, not a module failure.
Inspect the Sampling Line for Kinks or Disconnections
- Follow the full length of the sampling line from patient to module.
- Remove any kinks or compression points
- Ensure all connections are secure
Expected: Line is unobstructed and properly connected.
Why it matters: Physical obstruction is the most common cause of flow restriction.
Check for Moisture or Secretions in the Line
- Look for visible condensation, water, or patient secretions.
- If present, replace the sampling line
Expected: Clear, dry sampling line installed.
Why it matters: Moisture can block gas flow and damage internal components.
Inspect and Replace the Water Trap
- Remove and check the water trap:
- Empty if reusable, or replace if disposable
- Ensure it is properly seated after reinstalling
Expected: Clean, properly installed water trap with no blockage.
Why it matters: A full or clogged water trap restricts gas flow to the module.
Check Sampling Line Filter (if present)
- Some setups include inline filters.
- Inspect for blockage or discoloration
- Replace if needed
Expected: Filter allows free gas flow.
Why it matters: Blocked filters can mimic a full sampling line obstruction.
Verify Sampling Pump Operation
- Listen for the internal sampling pump:
- Check for normal operation (soft, consistent sound)
- Observe if waveform returns after clearing line
Expected: Pump operates normally and gas readings return.
Why it matters: Confirms the module is pulling gas correctly.
Test with a Known Good Sampling Line
- Replace entire sampling setup (line + trap + filter) with a known good set.
Expected: Gas readings return to normal.
Why it matters: Quickly isolates whether the issue is external vs internal.
If the Problem Persists
If all external components (sampling line, water trap, filter) have been replaced and the issue remains, the problem is likely internal to the gas module (pump, flow sensor, or internal blockage).
Remove the device from service, label it Out of Service, and send for repair or bench evaluation.
Knowing when to stop prevents unnecessary risk and protects patient safety.
Clinical Use Tip
Never troubleshoot gas sampling issues on an active patient. Always transition monitoring to a backup device before removing or replacing sampling components.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Gas readings absent and EtCO₂ waveform flat during case."
Cause
What was observed during troubleshooting.
Example:
"Sampling line and water trap found occluded with moisture."
Resolution
What action was taken.
Example:
"Replaced sampling line and water trap; verified normal gas readings restored."
Helpful Details to Include (If Known)
- Sampling line replaced
- Water trap condition (full/contaminated)
- Presence of moisture or secretions
- Pump sound observed
- Waveform restored or not
- Final device status (returned to service or sent for repair)
Final Thought
Gas sampling issues are most often caused by simple external obstructions. A structured approach—starting with the sampling line and moisture control—prevents unnecessary module replacement. Always prioritize patient safety and escalate appropriately when external causes are ruled out. Proper documentation ensures clarity and continuity of care.
That is successful troubleshooting.