On this page
Asset Type
Manufacturer
Model
What This Guide Helps With
This guide assists Clinical Engineering in troubleshooting flow or tidal volume discrepancies on a ResMed Astral ventilator. Symptoms may include delivered tidal volumes being higher or lower than set, inconsistent flow patterns, unexpected alarms related to volume, or patient-ventilator asynchrony. The guide focuses on external and verifiable checks before assuming internal malfunction.
Step-by-Step Troubleshooting
Verify Patient Circuit Connection
- Check that all tubing, humidifiers, filters, and patient interfaces are securely connected.
- Loose connections or disconnected circuits can cause inaccurate flow measurements or tidal volume delivery.
Inspect Circuit for Leaks
- Visually inspect the circuit for cracks, holes, or loose fittings.
- Use a leak test if the ventilator supports it. Even small leaks can drastically affect tidal volume readings.
Check Exhalation Port and Filters
- Ensure the exhalation port is not obstructed and filters are clean.
- Obstruction can cause inaccurate flow sensing and trigger low or high tidal volume alarms.
Verify Ventilator Settings vs Patient Requirements
- Confirm the correct mode (e.g., PS, CPAP, PCV, VC) is selected.
- Incorrect mode or improper parameters may appear as a volume discrepancy.
Inspect for Water or Condensation in Circuit
- Remove any pooled water from tubing or humidifiers.
- Fluid in the circuit can change flow characteristics, leading to inaccurate tidal volumes.
Check for Kinks or Obstructions in Tubing
- Straighten tubing and ensure there are no sharp bends.
- Obstructions alter delivered volumes and trigger alarms.
Examine Ventilator Battery or Power Supply
- Ensure stable power; low battery or fluctuating supply can affect flow sensors and measurements.
Replace Disposable Components
- Swap patient circuit, filters, and sensors with new units to rule out equipment wear.
If the Problem Persists
After completing all external checks, if discrepancies continue, the issue is likely internal (sensor malfunction, flow sensor miscalibration, or board-level error).
- Remove the ventilator from service.
- Label it “Out of Service.”
- Send for bench evaluation or manufacturer repair.
- Do not attempt internal sensor repairs without proper authorization.
Clinical Use Tip
Never troubleshoot flow or volume issues while the patient is connected to the ventilator if alternate ventilation is not immediately available.
Move the patient to a backup ventilator before testing.
Confirm alarms are functioning properly before returning the device to clinical use.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
“Clinician reports tidal volume delivered is inconsistent with set values; low and high tidal volume alarms observed.”
Cause
What was observed during troubleshooting.
Example:
“External inspection revealed circuit and filters intact, no visible leaks; flow discrepancies persist.”
Resolution
What action was taken.
Example:
“Ventilator removed from service, labeled Out of Service, and sent for manufacturer repair. Patient transitioned to backup device.”
Helpful Details to Include
- Circuit inspected for leaks, kinks, and condensation
- Filters and humidifiers checked or replaced
- Ventilator mode and settings verified
- Battery level confirmed stable
- Alarms tested and noted
Final Thought
Accurate tidal volume delivery is critical for patient safety. By following a logical, stepwise approach—checking connections, leaks, and circuit components—Clinical Engineering can rule out common external causes efficiently. Escalation to repair should be done promptly if discrepancies persist, ensuring patient safety and equipment reliability. Proper CCR documentation supports accountability and continuous quality improvement.
That is successful troubleshooting.