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What This Guide Helps With
Troubleshooting air or oxygen supply alarms caused by wall outlets, hoses, fittings, source pressure, crossed connections, or external gas-supply interruptions.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not troubleshoot a gas-supply failure while the Servo-i is actively supporting a patient.
Notify respiratory therapy and the clinical team immediately.
Transfer the patient to another verified ventilator or approved ventilation method.
Provide manual ventilation support when clinically required and directed by qualified staff.
Confirm adequate ventilation and oxygenation using independent monitoring.
Expected outcome: The patient is safely supported without depending on a ventilator with an unreliable gas supply.
Continue Clinical Engineering troubleshooting only after the Servo-i has been removed from patient use.
2. Confirm the Reported Gas-Supply Failure
Review the displayed alarm and determine whether the problem involves:
- Air supply pressure
- O₂ supply pressure
- Both gas supplies
- Intermittent supply loss
- Failure only during high-flow operation
- Unexpected delivered oxygen concentration
Record the exact alarm wording, when it occurred, and whether the alarm cleared after the device was disconnected from the patient.
Expected outcome: The affected gas source and failure pattern are clearly identified.
3. Inspect the Gas Hoses and Inlet Connections
Inspect the air and O₂ hoses from the ventilator to the source.
Check for:
- Loose or partially inserted fittings
- Kinked, crushed, stretched, or sharply bent hoses
- Damaged connectors
- Cuts, abrasion, or visible hose deterioration
- Contamination inside the fittings
- Air and O₂ hoses connected to the wrong inlets
- Unapproved adapters or extension hoses
Disconnect and firmly reconnect each hose to its correctly labeled ventilator inlet.
Expected outcome: Both hoses are secure, correctly routed, undamaged, and connected to the proper gas inlets.
If the alarm clears and the ventilator passes operational testing, stop troubleshooting.
4. Verify the Wall Gas Outlets
Confirm that each hose is fully seated in the correct wall outlet.
Test the suspected outlet using:
- Another verified ventilator
- An approved gas-pressure test device
- Another facility-approved method
Do not assume that gas is available because the connector physically locks into the outlet.
Expected outcome: The wall outlet provides the correct gas at an acceptable and stable pressure.
If the outlet fails, remove it from clinical use and notify Facilities or the department responsible for the medical gas system.
5. Try a Known-Good Gas Outlet
Move the Servo-i to verified air and oxygen outlets in another location when practical.
Reconnect both gas supplies and restart the ventilator according to facility procedure.
Expected outcome: If the alarm clears at the alternate outlets, the original wall outlet or medical gas zone is the likely cause.
Stop troubleshooting the ventilator and report the facility gas-supply problem.
6. Substitute Known-Good Gas Hoses
Replace the air and O₂ hoses one at a time with compatible, approved, known-good hoses.
Do not use hoses with questionable fittings, improvised adapters, or uncertain gas identification.
Expected outcome: If the alarm clears after replacing a hose, the original hose or connector was defective.
Remove the failed hose from service and complete the required operational verification before returning the ventilator to use.
7. Check Portable Cylinder Supplies When Used
When the ventilator is connected to cylinders, verify:
- The cylinder contains sufficient gas
- The valve is fully open
- The regulator is appropriate for medical gas service
- The regulator is producing stable pressure
- The hose is connected to the correct regulator outlet
- The cylinder is secured properly
- The regulator and fittings are free from visible damage
A cylinder gauge may show remaining pressure while the regulator cannot maintain adequate flow under load.
Expected outcome: The portable gas source supplies stable pressure during ventilator operation.
8. Check for a Facility-Wide Gas Interruption
Determine whether other ventilators or gas-powered devices in the same area are reporting similar problems.
Contact Facilities or the medical gas system operator to check for:
- Zone valve closure
- Pipeline maintenance
- Low central supply pressure
- Compressor failure
- Oxygen source interruption
- Recent construction or outlet servicing
Expected outcome: A facility-wide supply problem is either confirmed or ruled out.
9. Inspect the Ventilator Gas Inlet Area
With the ventilator disconnected from the patient, inspect the external gas inlet area for:
- Bent or damaged fittings
- Loose inlet connectors
- Contamination
- Evidence of liquid entry
- Missing or damaged labels
- Signs of impact
- Unusual hissing after connection
- Abnormal heat or odor
Do not insert tools into the gas inlets or attempt internal gas-module disassembly.
Expected outcome: The external inlet fittings are intact and show no evidence of leakage, contamination, or physical damage.
10. Restart and Observe the Alarm Sequence
With verified gas sources and known-good hoses connected:
- Power the Servo-i off.
- Wait for the shutdown process to complete.
- Restore power.
- Observe startup and gas-supply recognition.
- Record any alarm codes or messages that return.
A restart may clear a temporary detection condition, but it must not be used to dismiss a recurring supply alarm.
Expected outcome: Both gas supplies are detected normally and no supply alarm returns.
If the alarm clears, continue with a complete operational test before clinical use.
11. Perform an Operational Verification
Connect the ventilator to an approved test lung and verify:
- Startup completes normally
- Air and O₂ supplies are recognized
- Ventilation begins without gas-supply alarms
- The ventilator achieves the selected pressure and volume
- Delivered oxygen concentration is reasonable when checked with an approved analyzer
- Alarms activate appropriately
- No abnormal hissing, vibration, or odor is present
Follow the facility’s approved inspection process and current manufacturer service documentation.
Expected outcome: The ventilator operates normally under test conditions without recurring gas-supply faults.
If the Problem Persists
If verified wall outlets, known-good hoses, correct connections, adequate source pressure, and external fittings have been confirmed, the common external causes have been ruled out.
The failure may involve an internal gas inlet assembly, pressure sensor, gas module, valve, wiring connection, or control system. Internal gas-system diagnosis requires appropriate service documentation, test equipment, training, and calibration procedures.
The ventilator should be:
- Removed from service
- Labeled Out of Service
- Sent for qualified repair or bench evaluation
- Tested fully before being returned to clinical use
Knowing when to stop and escalate is proper troubleshooting. Do not bypass gas-supply alarms or return the ventilator to service based only on an alarm temporarily clearing.
Clinical Use Tip
Never troubleshoot an air or O₂ supply failure while the Servo-i is supporting a patient. Transfer the patient first and independently verify ventilation and oxygenation.
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 displayed an O₂ supply failure alarm and could not maintain the selected oxygen concentration."
Cause
What was observed during troubleshooting.
Example:
"The oxygen hose connector was worn and intermittently lost connection at the wall outlet; the ventilator operated normally with a known-good hose."
Resolution
What action was taken.
Example:
"Replaced the defective O₂ hose, connected the ventilator to verified air and oxygen sources, and completed test-lung and oxygen-concentration checks with no recurring alarms."
Helpful Details to Include (If Known)
- Exact gas-supply alarm message
- Whether air, O₂, or both supplies were affected
- Wall outlets tested
- Outlet pressure verified
- Alternate location tested
- Gas hoses swapped
- Cylinder and regulator condition
- Alarm behavior during startup
- Delivered FiO₂ analyzer reading
- Indicator lights or displayed codes
- Unusual sounds or gas leakage
- Unusual heat or smell
- Operational test results
- Final device status
Final Thought
Gas-supply alarms require immediate attention because they can affect ventilation and delivered oxygen concentration. Protect the patient first, verify external sources and hoses logically, and escalate when the problem points to the ventilator’s internal gas system. Clear CCR documentation preserves the evidence needed for safe repair and future trend review.
That is successful troubleshooting.