FDA Early Alert

FDA Issues Early Alert for Hamilton Medical Breathing Circuit Sets Following Reports of Serious Injuries

The U.S. Food and Drug Administration (FDA) has issued an Early Alert regarding certain Hamilton Medical coaxial breathing circuit sets used with HAMILTON-C1, HAMILTON-T1, and HAMILTON-MR1 ventilators after reports of impaired expiratory gas flow that may compromise patient ventilation.

According to Hamilton Medical, certain breathing circuit sets preassembled with expiratory valve assemblies may not function as intended due to adhesion of the expiratory valve membrane to the sealing ring. When this occurs, the valve may not open properly, restricting expiratory gas flow and impairing ventilation.

The FDA is evaluating the issue and has classified it as a potentially high-risk device concern.

Affected Devices

The alert applies to certain Hamilton Medical coaxial breathing circuit sets used with:

• • HAMILTON-C1 ventilators
  • HAMILTON-T1 ventilators
  • HAMILTON-MR1 ventilators

The affected products are intended to connect ventilators to patients during respiratory support and mechanical ventilation.

Potential Patient Risks

Hamilton Medical reported that the issue may result in:

• • Impaired exhalation
  • Elevated end-expiratory pressure
  • Reduced expiratory flow
  • Inadequate ventilation
  • Impaired gas exchange
  • Oxygen desaturation (hypoxemia)

If the malfunction occurs, the ventilator will generate an “Exhalation Obstructed” alarm.

The concern is particularly significant because the problem may not be detected during a standard pre-operative ventilator test unless a test lung is actively ventilated as part of the verification process.

According to Hamilton Medical, the malfunction typically becomes apparent within the first few breaths after ventilation begins.

As of May 13, 2026, the manufacturer has reported four serious injuries associated with this issue. No deaths have been reported.

Recommended Actions

Hamilton Medical recommends that healthcare facilities:

• • Review updated use instructions immediately.
  • Verify unimpeded expiratory gas flow by ventilating a test lung after completing the pre-operative test.
  • Remove and replace any breathing circuit set that triggers an “Exhalation Obstructed” alarm.
  • Ensure alternative ventilation methods are immediately available if the alarm occurs during patient use.
  • Notify all users of affected breathing circuit sets and post facility notices regarding the issue.

Affected products may continue to be used if the recommended risk mitigation measures are followed.

Regulatory Perspective

FDA Early Alerts are issued when the agency believes healthcare providers should be informed of a potentially significant device issue before a full regulatory assessment is completed.

This alert highlights an important lesson in ventilator risk management: successful completion of standard pre-use testing may not always identify component-level failures that occur under actual operating conditions.

Healthcare organizations should ensure respiratory therapists, clinical engineers, biomedical equipment personnel, anesthesiology teams, and critical care staff are aware of the updated testing requirements and troubleshooting procedures.

MDP Takeaway

Ventilator breathing circuits and expiratory valve assemblies are critical components of the respiratory support system. Any failure that restricts exhalation can quickly compromise gas exchange and patient oxygenation.

Organizations using Hamilton ventilators should promptly identify affected inventory, implement Hamilton Medical’s updated verification procedures, and ensure frontline clinical staff understand how to respond to “Exhalation Obstructed” alarms.

Given the reported serious injuries, facilities should treat this alert as a high-priority equipment management and patient safety issue.

Links

Read the FDA’s announcement here.