What criteria should I use to determine when to refer a patient with ARDS to secondary care?

Criteria for referral of a patient with acute respiratory distress syndrome (ARDS) to secondary care include:

• Presence of severe respiratory distress, such as marked chest recession, grunting, or a respiratory rate significantly elevated (e.g., over 70 breaths per minute in children), indicating respiratory failure requiring advanced support NICE NG9.
• Failure to maintain adequate oxygen saturation despite oxygen supplementation, typically persistent oxygen saturation below 92% on air, suggesting the need for hospital-level oxygen therapy and monitoring NICE NG9.
• Signs of exhaustion or decreased respiratory effort, which indicate impending respiratory failure and need for urgent intervention NICE NG9.
• Central cyanosis or other signs of hypoxia, which require emergency hospital care NICE NG9.
• Altered mental state or new onset of altered behaviour, which may indicate severe illness or sepsis complicating ARDS and necessitate urgent secondary care NICE NG51.
• Requirement for high oxygen concentrations (FiO2 ≥40%) to maintain adequate saturation (>92%), indicating severe respiratory compromise NICE NG51.
• Hemodynamic instability such as low systolic blood pressure (≤90 mmHg) or signs of poor perfusion (mottled or ashen appearance), which require hospital resuscitation facilities NICE NG51.
• Impaired immune status or presence of risk factors for severe disease, which lower the threshold for referral NICE NG9,NICE NG51.

In summary, any patient with ARDS showing signs of severe respiratory distress, hypoxia unresponsive to oxygen therapy, exhaustion, altered mental status, or hemodynamic instability should be referred immediately to secondary care for advanced management and monitoring.