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What This Guide Helps With
Measured tidal volume differs from the intended setting because of leaks, circuit conditions, settings, sensor issues, gas supply, or ventilation-system problems.
Step-by-Step Troubleshooting
1. Protect the Patient and Maintain Ventilation
If delivered ventilation is unreliable, immediately provide ventilation using an appropriate verified alternative. Do not continue testing the affected ventilator while a patient depends on it. Expected outcome: The patient receives dependable ventilation independently of the affected machine. The Atlan A350 can then be evaluated safely.
2. Confirm the Reported Volume Discrepancy
Record the ventilation mode, set tidal volume, observed measured volume, relevant alarm condition, patient circuit configuration, and whether the problem is continuous or intermittent. Reproduce the issue using an appropriate test lung or approved analyzer rather than a patient. Expected outcome: The difference between the intended and measured ventilation is objectively confirmed. If delivered volume is normal during controlled testing, investigate setup or clinical-interface factors before assuming machine failure.
3. Inspect the Breathing Circuit for Leaks or Disconnections
Check the inspiratory and expiratory limbs, Y-piece, reservoir bag, filters, adapters, sampling connections, and other external breathing-system connections. Look for loose fittings, cracks, damaged tubing, disconnected ports, or other obvious sources of lost volume. Expected outcome: The breathing circuit is intact and correctly connected. If correcting a leak restores expected ventilation, repeat system testing and proceed to final verification.
4. Check for Circuit Obstruction or Kinking
Inspect tubing, filters, connectors, and external accessories for compression, kinks, fluid accumulation, blockage, or incorrect positioning that could restrict gas flow. Replace suspect disposable components with known-good compatible components when appropriate. Expected outcome: The external gas pathway is unobstructed. If removing an obstruction restores expected tidal volume, troubleshooting can stop after successful functional verification.
5. Verify Ventilation Controls and Settings
Confirm the selected ventilation mode and intended settings are appropriate for the test setup. Check for inadvertent setting changes or configuration conditions that could explain the observed behavior. Do not alter protected or service-level parameters without authorization. Expected outcome: The machine is operating with the intended ventilation configuration. If correcting an incorrect setting resolves the volume discrepancy, verify operation before return to service.
6. Check Gas Supply Availability
Confirm required pipeline gases are connected and available. Inspect supply hoses for looseness, kinks, or damage and verify there are no concurrent gas-supply alarms. Expected outcome: The machine has the required external gas supply. If restoring a gas supply corrects ventilation performance, complete system testing before release.
7. Evaluate External Sensors and Measurement Path
Inspect externally accessible flow-sensing components and related connections for contamination, moisture, incorrect installation, or damage. If the machine requires a user-accessible sensor calibration or system test, perform only the approved procedure. Expected outcome: Flow measurement is available and consistent with the controlled test setup. If sensor correction or approved calibration restores accurate volume measurement, perform final verification.
8. Compare With Approved Test Equipment
Connect an appropriate anesthesia/ventilator analyzer and test lung. Compare delivered ventilation with the machine's displayed measurements across the conditions required by your facility or manufacturer procedure. Do not infer a ventilator output failure solely from the machine's displayed value. Expected outcome: Independent measurement confirms acceptable and consistent ventilation performance. If performance is satisfactory after an external correction, troubleshooting can stop.
9. Perform Final Functional Verification
Repeat the applicable system test, ventilation check, leak check, alarm verification, and functional testing after any correction. Expected outcome: Delivered and displayed ventilation are stable and appropriate under controlled test conditions, and required return-to-service checks pass.
10. Escalate if Volume Delivery Remains Unreliable
If the machine cannot consistently deliver or accurately measure ventilation after external causes are ruled out, remove it from service. Expected outcome: An unreliable ventilator is not returned to patient care and receives qualified service evaluation.
If the Problem Persists
External circuit leaks, obstructions, gas supplies, ventilation settings, accessories, and accessible measurement components have been evaluated. Remaining possibilities may involve internal pneumatic regulation, valve performance, pressure or flow sensing, calibration, control electronics, or other service-level conditions. The device should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using appropriate manufacturer documentation and approved test equipment
- Repaired or configured only by qualified personnel
After service, verify ventilation output using approved independent test equipment and complete all required system, alarm, and return-to-service testing. Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
When tidal volume delivery is questionable, trust patient safety over continued troubleshooting and immediately provide an alternate verified means of ventilation.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Anesthesia staff reported the Drager Atlan A350 was displaying substantially less tidal volume than the volume selected during setup."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found a loose connection at the patient circuit that allowed delivered volume to escape."
Resolution
What action was taken.
Example:
"Clinical Engineering secured the connection, verified delivered volume with approved test equipment, completed the system checks, and returned the machine to service."
Helpful Details to Include (If Known)
- Ventilation mode
- Set and measured tidal volumes
- Alarm behavior
- Circuit and filter condition
- Leak-test results
- Gas supply status
- Flow sensor condition
- Known-good substitutions
- Independent analyzer results
- Results before and after correction
- Final device status
- Ventilation mode
- Set and measured tidal volumes
- Alarm behavior
- Circuit and filter condition
- Leak-test results
- Gas supply status
- Flow sensor condition
- Known-good substitutions
- Independent analyzer results
- Results before and after correction
- Final device status
Final Thought
Unreliable ventilation is a patient-safety issue. Rule out circuit, setting, supply, and measurement problems methodically, confirm performance independently, and escalate any machine that cannot be proven reliable. That is successful troubleshooting.