What are the indications and guidelines for using Transnasal Humidified Rapid Insufflation Vent Exchange (THRIVE) in airway management?

THRIVE (Transnasal Humidified Rapid Insufflation Ventilatory Exchange) in Airway Management

Primary Indication and Mechanism

THRIVE is recommended by the American Society of Anesthesiologists as an apneic oxygenation technique to maximize oxygenation during unanticipated and emergency difficult airway management, particularly in "cannot oxygenate or ventilate" scenarios. 1

THRIVE delivers warmed, humidified oxygen at high flow rates (30-70 L/min) through nasal cannulae, creating continuous positive airway pressure while maintaining airway patency and providing CO2 clearance through supraglottic flow vortices. 2 This represents a significant advancement over traditional nasal oxygen at 15 L/min, which would be intolerable without warming and humidification. 2

Specific Clinical Applications

Emergency and Difficult Airway Management

• Primary use: During anticipated or unanticipated difficult intubation when multiple attempts may be required, extending safe apnea time beyond the 6-8 minutes achieved with standard preoxygenation alone. 1, 3
• Critical care intubation: British guidelines recommend THRIVE (or high-flow nasal oxygen at 30-70 L/min) as an optimal oxygenation technique during rapid sequence intubation in critically ill adults, particularly those with pulmonary shunt and limited respiratory reserve. 1
• Application during intubation attempts: Nasal oxygen at 15 L/min (or THRIVE) should be applied throughout all airway management efforts, from preoxygenation through intubation attempts. 1

Elective Surgical Applications

• Laryngopharyngeal surgery: THRIVE enables tubeless anesthesia for short airway procedures, with median apnea times of 13-27 minutes reported in case series. 4
• Shared airway procedures: Particularly valuable in otolaryngology and head/neck surgery where an uninterrupted surgical field is critical. 5
• Morbidly obese patients: THRIVE can provide adequate oxygenation during short apneic laryngeal procedures in obese patients without excessive hypercarbia, despite their limited safe apnea time. 6

Technical Implementation

Flow Rates and Settings

• Adult patients: 30-70 L/min of warmed, humidified oxygen. 1, 2
• Standard nasal cannulae alternative: If THRIVE equipment unavailable, use standard nasal cannulae at 5 L/min during preoxygenation, increased to 15 L/min after loss of consciousness. 1
• Pediatric patients (10-20 kg): 2 L/kg/min with 100% oxygen, though this did not extend safe apnea time beyond low-flow oxygen in one randomized trial. 7

Airway Patency Requirements

Critical caveat: THRIVE only works in patients with patent airways. 8

• Nasopharyngeal airway placement is noninferior to jaw thrust for maintaining airway patency during THRIVE, with both achieving PaO2 >42 kPa and PaCO2 ~10.5 kPa at 20 minutes of apnea. 8
• Consider nasopharyngeal airway insertion if jaw thrust cannot be continuously maintained. 8

Contraindications

• Severe facial trauma or suspected skull base fractures: Absolute contraindication to high-flow nasal oxygenation. 1
• Closed airway: THRIVE is ineffective without airway patency. 8

Integration with Other Techniques

Preoxygenation Strategy

1. Position patient 20-30° head-up to increase functional residual capacity and extend safe apnea time by ~30%. 3
2. Apply tight-fitting facemask with CPAP (5-10 cm H2O) if oxygenation impaired, targeting end-tidal oxygen ≥90%. 1, 3
3. Apply THRIVE or standard nasal cannulae during preoxygenation phase. 1
4. Continue nasal oxygen/THRIVE throughout all intubation attempts. 1

Combination with Facemask Ventilation

Important warning: Concomitant use of THRIVE during facemask ventilation with a tight-fitting mask can result in dangerously high airway pressures. 1 If facemask ventilation is required between intubation attempts, either:

• Move THRIVE cannulae to corner of mouth to allow adequate mask seal, or
• Temporarily discontinue THRIVE during facemask ventilation. 1

Physiological Effects and Limitations

CO2 Management

• THRIVE provides CO2 clearance, preventing rapid CO2 accumulation during apnea, unlike traditional apneic oxygenation. 2, 3
• In pediatric patients (10-20 kg), CO2 increased at 0.57 kPa/min with no ventilatory effect observed at 2 L/kg/min flow rates. 7
• In adults, THRIVE maintains adequate gas exchange for median apnea times of 13-27 minutes in surgical series. 4

Oxygen Concentration Considerations

• 100% oxygen is essential: In pediatric studies, THRIVE with 30% oxygen resulted in significantly shorter safe apnea times (3.0 minutes) compared to 100% oxygen (7.6 minutes). 7
• Always use 100% oxygen for apneic oxygenation applications. 7

Evidence Quality and Guideline Support

The 2022 ASA Difficult Airway Guidelines explicitly list "high-flow nasal cannula oxygen/transnasal humidified rapid insufflation ventilatory exchange" as a recommended technique to maximize oxygenation during emergency difficult airway management. 1 The 2018 British guidelines for critically ill adults similarly recommend THRIVE/HFNO as optimal oxygenation techniques, though they note evidence shows no harm but no definitive outcome benefits, making the evidence inconclusive for routine use. 1

Key limitation: Most evidence consists of case series and observational studies in laryngopharyngeal procedures, with limited high-quality randomized controlled trials. 4 The single pediatric RCT showed no advantage over low-flow oxygen. 7

Practical Algorithm for THRIVE Use

1. Assess airway patency: Confirm patient can maintain open airway (spontaneously or with adjuncts). 8
2. Check for contraindications: Rule out facial trauma/skull base fractures. 1
3. Position optimally: 20-30° head-up. 3
4. Initiate THRIVE: 30-70 L/min warmed, humidified 100% oxygen via nasal cannulae. 2
5. Ensure airway patency: Use jaw thrust or nasopharyngeal airway. 8
6. Monitor continuously: Pulse oximetry and capnography if available. 1
7. Limit apnea time: Plan for definitive airway within safe window (typically <20-30 minutes in adults). 4
8. Have rescue plan: Prepare for front-of-neck airway if oxygenation fails. 1