THRIVE

Link: anae0070-0323.pdf

Transnasal Humidified Rapid Insufflation Ventilatory Exchange (THRIVE)

Background

• Technique previously described in the awake population for avoidance of re-intubation and atelectasis post operatively, in the treament of ARDS and to manage dyspnoea in CCF.
• Gaining popularity for use at induction of anaesthesia by extending the apnoeic window until intubation.
• THRIVE delivered by OptiFlow system (Fisher and Paykel Healthcare Ltd, Panmure, Auckland, New Zealand) demonstrated extension of median apnoea time to 14 minutes in a cohort of 25 patients with difficult airways undergoing GA for hypopharyngeal or laryngotracheal surgery.
• Has been used as the sole method of oxygenation in laryngotracheal procedures. Advantageous as it provides a clear airway for surgical team.

Physiology

Classic apnoeic oxygenation/aventilatory mass flow describes gas exchange through flow dependent dead space flushing.

• A physiological phenomenon occurring when a patent airway exists between the lungs and exterior and oxygen is delivered causing “micro ventilation” through multiple vortexes.
• The difference between the alveolar rates of oxygen removal and CO2 excretion generates negative pressure gradient of up to 20cmH2O which drives oxygen into the lungs from the oropharynx.

The difference between standard “apnoeic oxygenation” and THRIVE is the limitation in CO2 rise. (0.45 vs 0.15kPa rise per minute). The physiology behind this is complicated and not yet fully understood, but thought to be due to the high flow rates employed by the THRIVE technique.

Continuous insufflation at 60L/min provides CPAP in trachea of 7cmH2O, splinting the airways and reducing shunting.

Technique

Uses high flow (50-70L/min) nasal specs and humidifier.

Jaw thrust must be used throughout to maintain patent passageway.