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What This Guide Helps With
Troubleshoots abnormal delivered volume caused by circuit leaks, sensors, test setup, settings, resistance, compliance, accessories, or ventilator performance faults.
Step-by-Step Troubleshooting
1. Protect the Patient Before Evaluating Volume Delivery
Do not troubleshoot suspected inaccurate or unstable tidal volume while a patient depends on the affected ventilator. Transfer the patient to another verified ventilator or approved ventilation method.
Expected outcome: The patient remains safely ventilated while the Savina 300 is evaluated with test equipment.
2. Confirm the Volume Complaint
Determine whether the reported problem is:
- Delivered tidal volume lower than expected
- Higher than expected
- Breath-to-breath instability
- Difference between inspired and expired values
- Difference between ventilator display and external analyzer
Record the ventilation mode and relevant observed settings without changing them unnecessarily.
Expected outcome: The abnormal volume behavior is reproduced or clearly documented.
3. Verify the Test Setup
Connect an appropriate ventilator analyzer and test lung using a correctly assembled circuit.
Check that adapters, filters, humidification components, and test accessories are not introducing an unintended leak or restriction.
Expected outcome: The test setup is valid and suitable for comparing delivered and measured volume.
4. Inspect the Breathing Circuit for Leaks
Inspect all tubing, connectors, humidifier components, water traps, adapters, and caps for loose connections, cracks, or improper assembly.
Expected outcome: No significant external leak is present. If correcting a circuit leak stabilizes volume delivery, repeat verification and stop troubleshooting when performance is acceptable.
5. Inspect for Circuit Restriction
Check for:
- Kinked tubing
- Obstructed filters
- Water accumulation
- Blocked accessories
- Pinched hoses
- Incorrectly installed valves
Expected outcome: Gas can move freely through the circuit. If removing a restriction restores stable volume delivery, perform final verification.
6. Verify Flow Sensor Condition
Confirm the flow sensor is recognized, correctly installed, clean, dry, and calibrated as applicable.
Substitute a known-good compatible sensor if the measurement is questionable.
Expected outcome: Flow measurement is stable and sensor-related errors are absent. If replacing the sensor resolves the discrepancy, stop after final verification.
7. Review Ventilator Settings
Verify the selected mode, target values, pressure limits, trigger settings, PEEP, and other relevant controls are appropriate for the bench test being performed.
Do not alter protected configuration or clinical settings solely to make the device appear to pass.
Expected outcome: The observed volume behavior is consistent with the selected test settings and mode.
8. Compare With a Known-Good Test Condition
Use a known-good test lung and, when appropriate, simplify the circuit by removing nonessential accessories.
Compare several consecutive breaths rather than judging a single breath.
Expected outcome: Delivered volume remains stable under a controlled test condition. If instability disappears after removing an accessory, evaluate that accessory separately.
9. Verify Pressure and Flow Behavior
Observe pressure, flow, and volume simultaneously using approved test equipment. An abnormal pressure limit, leak, trigger condition, or gas-delivery problem can create an apparent volume issue.
Expected outcome: Pressure and flow remain consistent with the selected ventilation condition and measured tidal volume is stable.
10. Escalate Unverified Volume Performance
If known-good external components, sensors, circuit, and test equipment do not resolve the abnormal volume, remove the ventilator from service.
Expected outcome: The ventilator is either verified to deliver volume correctly or escalated for further evaluation.
If the Problem Persists
External circuit, leak, restriction, sensor, setup, and setting causes have been ruled out. Remaining possibilities may involve turbine performance, internal pressure or flow measurement, pneumatic regulation, control electronics, or another service-level ventilation fault.
The ventilator should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using appropriate Drager documentation and calibrated ventilator test equipment
- Repaired or calibrated only by qualified personnel
After repair, complete applicable volume, pressure, flow, oxygen, leak, and alarm testing before return to service.
Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
When comparing tidal-volume readings, verify the entire circuit and measurement location so a setup difference is not mistaken for ventilator failure.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Respiratory Therapy reported that delivered tidal volume from the Savina 300 was lower and unstable during a pre-use check."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found a partially disconnected breathing-circuit connection producing an intermittent leak."
Resolution
What action was taken.
Example:
"The circuit connection was secured and the ventilator demonstrated stable tidal-volume delivery on a calibrated analyzer and test lung."
Helpful Details to Include (If Known)
- Ventilation mode
- Reported volume behavior
- Circuit condition
- Leak-test result
- Filter and humidifier condition
- Flow-sensor condition
- External analyzer result
- Test-lung condition
- Results before and after correction
- Final device status
Final Thought
Volume discrepancies should be evaluated as a complete breathing-system problem before internal failure is assumed. Protect the patient, verify the test setup and external components, measure performance objectively, and escalate anything that cannot be verified.
That is successful troubleshooting.