Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE): a physiological method of increasing apnoea time in patients with difficult airways
What's it About?
The paper looks at a particular method of providing this in the form of the OptiFlow system, providing transnasal humidified oxygen at high flow rate (70 L/min). The study looked at a group of 25 patients who were known or suspected high risk of difficult intubation and/or rapid desaturation at induction. They were preoxygenated, had anaesthesia induced, and apnoeic oxygenation continued whilst the airway was secured, with airway opening maneuvers still being maintained. Because of the difficult nature of the airways, this resulted in fairly significant apnoea times, but this wasn’t artificially extended beyond clinical need. They measured a variety of parameters through this, most notably the lowest O2 sats that resulted and the end tidal CO2 recorded at the recommencement of ventilation.
What Did They Find?
The authors also used the end tidal CO2 (or in a few cases arterial PCO2) values to estimate the rate of climb in arterial CO2 levels during this apnoea, coming up with a value of 0.15 kPa/min, somewhat less than several earlier studies that they describe. There were, reassuringly, no episodes of complications arising from the raised PaCO2 or acidaemia
Is It Any Good?
Thanks again for reading and please let me know your thoughts on both apnoeic oxygenation and this paper, especially if it is something you are using currently in critical care of general anaesthetic practice. If you’ve not heard much about it before some of the links below are well worth a read. Bye for now.
- Preoxygenation and Prevention of Desaturation During Emergency Airway Management - Annals of Emergency Medicine. Mar 2012
- THRIVE - Anaesthesia. Nov 2014
- Difficult Airway Society - Update on 2015 intubation guidelines
Image courtesy of Praisaeng/freedigitalphots.net