How do I set up an Airvo (high flow nasal oxygen therapy) machine?

Setting Up the Airvo Machine (High Flow Nasal Oxygen Therapy)

Important Note

The Airvo is a high-flow nasal oxygen (HFNO) device, not a non-invasive ventilator (NIV/BiPAP). While the provided guidelines focus primarily on NIV setup, the principles of oxygen delivery and monitoring apply to HFNO therapy. The Airvo delivers heated, humidified oxygen at high flow rates but does not provide pressure support like NIV devices 1, 2.

Initial Setup Steps

1. Equipment Assembly

• Connect the Airvo device to oxygen and air supply sources (wall outlets or cylinders) 2
• Attach the heated humidifier chamber and fill with sterile water to the indicated level 2
• Connect the single heated breathing circuit from the humidifier to the nasal cannula interface 2
• Select appropriately sized nasal cannula (small, medium, or large) based on patient's nares size 3

2. Initial Settings

Flow Rate:

• Start at 30-40 L/min for most adults with acute hypoxemic respiratory failure 2, 3
• Can titrate up to 60 L/min based on patient comfort and clinical response 1, 3
• Lower flows (10-20 L/min) may be appropriate for less severe hypoxemia 2

FiO2 (Oxygen Concentration):

• Begin at 0.40-0.60 (40-60%) for hypoxemic patients 2
• Titrate to achieve target SpO2 of 94-98% in most patients, or 88-92% in those at risk of hypercapnia (COPD, obesity hypoventilation) 4, 5

Temperature:

• Set humidifier to 37°C (body temperature) for optimal comfort and mucociliary function 2, 3
• Can adjust between 34-37°C based on patient tolerance 3

3. Application to Patient

• Explain the therapy to the patient before starting 4
• Position nasal prongs in nares without forcing - should fit comfortably with minimal leak 3
• Secure the tubing to prevent displacement but avoid excessive tension 3
• Attach pulse oximeter to monitor SpO2 continuously 4
• Instruct patient they can eat, drink, and speak normally with the device in place 3

4. Monitoring and Adjustment

Initial Assessment (within 30-60 minutes):

• Monitor respiratory rate, work of breathing, and SpO2 4
• Check arterial blood gases if patient has hypercapnia risk or severe respiratory distress 4
• Assess patient comfort and tolerance 1, 3

Titration Strategy:

• If SpO2 remains <90% despite initial settings, increase FiO2 first, then consider increasing flow rate 2, 3
• If patient reports discomfort from high flow, reduce flow rate by 5-10 L/min increments 3
• Wean FiO2 as SpO2 improves to maintain target saturations 2

5. When to Escalate Care

Consider NIV or intubation if:

• Worsening respiratory acidosis (pH <7.30) despite HFNO 4, 5
• Persistent hypoxemia (SpO2 <85%) on maximum HFNO settings (60 L/min, FiO2 1.0) 4, 2
• Increasing work of breathing or respiratory rate >35 breaths/min 4, 5
• Altered mental status or inability to protect airway 5
• Hemodynamic instability 6, 5

Key Physiological Effects

The Airvo provides several therapeutic benefits beyond simple oxygen delivery 1, 2, 7:

• Anatomical dead space washout - high flows clear CO2 from upper airways 1, 2
• Positive end-expiratory pressure (PEEP) effect - generates 2-5 cmH2O pressure (higher with mouth closed) 7
• Consistent FiO2 delivery - high flows exceed patient's inspiratory demand 1, 2
• Optimal humidification - maintains mucociliary function and patient comfort 2, 3

Common Pitfalls to Avoid

• Inadequate flow rates - flows <30 L/min may not provide sufficient benefit in acute respiratory failure; start at 30-40 L/min 2, 3
• Incorrect cannula sizing - too large causes discomfort and nasal trauma; too small increases resistance 3
• Delayed escalation - HFNO is not a substitute for NIV or intubation when these are clearly indicated; reassess within 1-2 hours 4, 1
• Excessive oxygen in COPD patients - maintain SpO2 88-92% in hypercapnic patients to avoid worsening CO2 retention 4, 5
• Inadequate humidification - ensure water chamber is filled and temperature set appropriately to prevent airway drying 2, 3

Device-Specific Considerations

For the Airvo 2 specifically:

• When using nebulized medications, place vibrating mesh nebulizer at the humidifier outlet for optimal drug delivery 8
• The Airvo 2 may deliver slightly lower inhaled medication doses compared to Optiflow when nebulizer is at humidifier 8
• Ensure the heated circuit is properly connected to maintain temperature and humidity 2