AUTHOR=Cour Martin , Guérin Claude , Degivry Florian , Argaud Laurent , Louis Bruno 

TITLE=Delivery of high flow oxygen through nasal vs. tracheal cannulas: A bench study

JOURNAL=Frontiers in Medicine

VOLUME=Volume 9 - 2022

YEAR=2023

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.1068428

DOI=10.3389/fmed.2022.1068428

ISSN=2296-858X

ABSTRACT=Background: The use of high flow oxygen therapy (HFOT) has exploded during the COVID-19 pandemic. HFOT can be delivered through both dedicated devices and ICU ventilators. HFOT can be connected to the patient via a nasal canula (NC). In intubated patients, a tracheal canula (TC) is used instead. We aimed at comparing the work of breathing (WOB) with TC and NC. We hypothesized the WOB should be lower with the former and explored whether differences exist among HFOT devices.
Methods: Seven HFOT devices (three dedicated and 4 ICU ventilators were connected to a manikin head (Laerdal Medical) through a NC (Fisher and Paykel Healthcare) or a TC (Fisher and Paykel Healthcare). Each device was also attached to a manikin head associated with a lung simulator (ASL5000, Ingmar Medical) set with a 40ml/cmH2O compliance, 10 cmH2O/L/s resistance and a sinusoidal inspiratory effort (Muscular Pressure 10 cmH2O, rate 30 breaths/min). HFOT was delivered at 40 L/min at 21% inspired oxygen fraction. Total WOB per breath and its resistive and elastic components were automatically analyzed breath by breath over the last 20 breaths by using the Campbell’s diagram. 
Results: WOB and its resistive and elastic components were significantly lower with TC than with NC for every device, and systematically lower with the reference device than with the others. These differences were, however, very small and may be not clinically relevant.
Conclusion: WOB is lower with TC than with NC and with the reference device as compared to the most recent ones.