On this page
Asset Type
Manufacturer
Model
What This Guide Helps With
Troubleshooting disconnection or low-pressure alarms caused by circuit leaks, loose connections, flow-sensor problems, accessories, test-lung setup, or incorrect alarm limits.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not troubleshoot a persistent disconnection or low-pressure alarm while the HAMILTON-C6 is 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 when clinically required and performed by qualified personnel.
- Confirm adequate ventilation and oxygenation using independent monitoring.
Expected outcome: The patient is safely supported without relying on a ventilator that may not be delivering the intended pressure or volume.
Continue Clinical Engineering troubleshooting only after the affected ventilator has been removed from patient use.
2. Confirm the Exact Alarm Condition
Review the active alarm message and alarm history. Determine whether the device reports:
- Disconnection
- Pressure low
- Expiratory minute volume low
- Tidal volume low
- Flow sensor error
- Apnea
- Multiple related alarms
Record whether the alarm occurs continuously, intermittently, during inspiration, or only with certain settings.
The low-pressure alarm is generated when the ventilator does not reach the configured lower airway-pressure limit.
Expected outcome: The specific alarm behavior and the conditions that trigger it are identified.
3. Inspect the Patient Circuit for Complete Disconnection
Trace the entire breathing circuit from the ventilator to the patient connection or test lung.
Check:
- Inspiratory limb connection
- Expiratory limb connection
- Y-piece
- Patient interface connection
- Flow-sensor connections
- Humidifier chamber connections
- Nebulizer adapter
- Water traps
- Sampling adapters
- Circuit extension tubing
Reseat every connection securely. Look for tubing that appears connected but is only partially inserted.
Expected outcome: All circuit components are fully seated with no open or disconnected ports.
If reconnecting the circuit resolves the alarm and the ventilator passes operational testing, stop troubleshooting.
4. Check for Cracks, Tears, or Loose Components
Inspect the complete circuit for:
- Split tubing
- Cracked connectors
- Damaged Y-pieces
- Loose swivel adapters
- Missing caps
- Open suction or sampling ports
- Poorly seated humidifier chambers
- Damaged test lungs
- Loose exhalation components
Flex tubing gently while operating the ventilator on a test lung. An intermittent alarm may indicate a crack that opens when the circuit moves.
Expected outcome: No visible or intermittent circuit leak is found.
Replace any questionable disposable component before continuing.
5. Verify the Flow Sensor Installation
Inspect the proximal flow sensor and its tubing or electrical connections, depending on the installed configuration.
Confirm that:
- The sensor is installed in the correct orientation.
- Both flow-sensor lines or connectors are secure.
- The lines are not crossed, kinked, wet, blocked, or disconnected.
- The sensor body is not cracked or contaminated.
- The sensor matches the selected patient category.
- Any required calibration has been completed successfully.
A disconnected or incorrectly installed flow sensor may produce inaccurate volume measurements and alarms that resemble a circuit disconnection.
Expected outcome: The correct flow sensor is properly installed, recognized, and functioning.
If the alarm clears after replacing or correctly installing the sensor, complete the required preoperational test and stop.
6. Inspect the Expiratory Valve Assembly
Verify that the expiratory valve assembly is:
- Present
- Correctly assembled
- Fully seated
- Clean and dry
- Free of visible damage
- Appropriate for the selected patient category
Check the expiratory membrane for incorrect positioning, wrinkles, tears, or contamination. Do not perform internal disassembly beyond routine user-removable components.
Expected outcome: The expiratory valve assembly is properly installed and able to seal during inspiration.
7. Evaluate Humidifier and Accessory Connections
Temporarily simplify the circuit when safe and appropriate for bench testing.
Inspect or remove unnecessary accessories one at a time, including:
- Humidifier chamber
- HME or HMEF
- Nebulizer adapter
- Closed-suction adapter
- Capnography adapter
- Circuit extension
- Specialty connectors
Reconnect the ventilator to a verified test lung after each change.
Additional components can affect resistance and the ventilator’s ability to identify a patient-side disconnection. Hamilton advises appropriately setting lower pressure and volume alarm limits when accessories are placed between the flow sensor and patient.
Expected outcome: A leaking, incorrectly assembled, or incompatible accessory is identified or ruled out.
8. Test With a Known-Good Circuit and Test Lung
Install a complete, compatible, known-good breathing circuit, flow sensor, expiratory valve assembly, and test lung.
Use the appropriate adult, pediatric, or neonatal setup. Do not combine components from different circuit configurations unless specifically approved.
Start ventilation using controlled test settings and monitor:
- Peak pressure
- PEEP
- Delivered tidal volume
- Expiratory tidal volume
- Minute volume
- Leak percentage
- Pressure and flow waveforms
Expected outcome: The ventilator reaches the expected pressure and maintains stable ventilation without a disconnection alarm.
If the alarm disappears, replace the original circuit or accessory responsible for the leak.
9. Verify Patient Category and Circuit Configuration
Confirm that the selected patient category matches the installed circuit and flow sensor.
Check:
- Adult/pediatric versus neonatal selection
- Patient height or ideal body weight entry
- Ventilation mode
- Circuit type
- Flow-sensor type
- Invasive versus noninvasive mode
- Mask or interface selection when applicable
An incorrect patient category or mode can produce inappropriate pressure, volume, leak-compensation, or alarm behavior.
Expected outcome: The device configuration matches the installed breathing system and intended test setup.
10. Review the Low Pressure Alarm Limit
Compare the configured lower pressure alarm limit with the actual airway pressure achieved during test ventilation.
Check whether:
- The lower limit is set above the expected inspiratory pressure.
- The pressure target or support level was recently reduced.
- The alarm limit was carried over from a previous patient profile.
- PEEP and pressure-support settings are appropriate for the selected mode.
Do not disable or reduce alarm limits merely to silence an unresolved alarm. Alarm settings must remain clinically appropriate and be established by authorized clinical personnel before patient use.
Hamilton notes that proper lower pressure and volume alarm limits are important for detecting patient disconnection.
Expected outcome: The alarm limit is appropriate for the configured test conditions and does not mask a genuine circuit problem.
11. Check for Excessive Leak in Noninvasive Modes
When the reported problem occurred during NIV, inspect:
- Mask or interface condition
- Elbow and anti-asphyxia valve
- Exhalation port configuration
- Mask sizing
- Circuit compatibility
- Leak-compensation settings
- Open or unintended leak paths
Bench-test using a compatible NIV interface or approved test setup. Some intentional leak is expected in NIV, but excessive or unstable leak may prevent the ventilator from reaching the required pressure.
Expected outcome: Intentional and unintentional leak sources are correctly identified.
12. Run the Preoperational Check
After correcting external issues, perform the manufacturer-required preoperational check using the correct circuit, flow sensor, expiratory valve, and test lung.
Confirm successful completion of applicable:
- Circuit tightness or leak testing
- Flow-sensor calibration
- Expiratory-valve testing
- Alarm testing
- Pressure delivery verification
Do not return the ventilator to service when a required test fails.
Expected outcome: The HAMILTON-C6 passes all required checks and maintains stable pressure and volume on a verified test lung.
13. Perform an Extended Functional Test
Operate the ventilator on a test lung long enough to confirm that the alarm does not return intermittently.
Test several representative conditions within facility policy:
- Low and moderate respiratory rates
- Different inspiratory pressures
- PEEP delivery
- Pressure-controlled ventilation
- Volume-targeted ventilation
- Alarm activation using a controlled circuit disconnection
Verify that the ventilator recognizes the intentional disconnection and that audible and visual alarms activate correctly.
Expected outcome: Ventilation remains stable, and the alarm system responds appropriately to an intentional disconnection.
If the Problem Persists
If the alarm remains with a known-good circuit, flow sensor, expiratory valve assembly, test lung, appropriate settings, and successful external inspections, common external causes have been ruled out.
The problem may involve internal pressure measurement, flow measurement, valve control, pneumatic leakage, turbine performance, or another internal system fault.
The ventilator should be:
- Removed from service
- Labeled Out of Service
- Sent for authorized repair or bench evaluation
- Accompanied by the recorded alarm messages and test results
Do not perform internal pneumatic or board-level repairs without appropriate Hamilton service training, documentation, and test equipment. Knowing when to stop and escalate is proper troubleshooting.
Clinical Use Tip
Never use a patient as the test load for a suspected circuit disconnection or pressure-delivery problem. Move the patient first, then troubleshoot with a verified circuit and test lung.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Respiratory therapy reported that the HAMILTON-C6 displayed repeated disconnection and low-pressure alarms and could not maintain the expected airway pressure."
Cause
What was observed during troubleshooting.
Example:
"Inspection found a cracked Y-piece connector that produced a large circuit leak and prevented the ventilator from reaching the configured lower pressure limit."
Resolution
What action was taken.
Example:
"Replaced the damaged circuit, calibrated the flow sensor, completed the preoperational check, and verified stable ventilation and alarm operation on a test lung."
Helpful Details to Include (If Known)
- Exact alarm message
- Alarm priority and frequency
- Patient category selected
- Ventilation mode and pressure settings
- Lower pressure alarm limit
- Circuit and flow-sensor type
- Circuit connections inspected
- Known-good circuit installed
- Expiratory valve inspected
- Humidifier or accessories removed
- Leak percentage observed
- Peak pressure and PEEP readings
- Flow-sensor calibration result
- Preoperational check result
- Alarm function verified
- Final device status
Final Thought
Disconnection and low-pressure alarms should be approached as potential failures to deliver ventilation. Protect the patient first, inspect the entire external breathing system, verify configuration and alarm limits, test with known-good components, and escalate when stable pressure cannot be confirmed. Clear CCR documentation preserves the findings and supports safe follow-up.
That is successful troubleshooting.