TY - JOUR
T1 - Upper airway pressure distribution during nasal high-flow therapy
AU - Hebbink, Rutger H.J.
AU - Duiverman, Marieke L.
AU - Wijkstra, Peter J.
AU - Hagmeijer, Rob
N1 - Funding Information:
This research is financially supported by Longfonds, Fisher & Paykel Healthcare Ltd. and Vivisol Nederland BV, under Longfonds project number 10.1.17.184. The sponsors were not involved in the study design, the collection, analysis and interpretation of data, or the writing or submission of the article.
Publisher Copyright:
© 2022
PY - 2022/6
Y1 - 2022/6
N2 - Two working mechanisms of Nasal High-Flow Therapy (NHFT) are washout of anatomical dead space and provision of positive end-expiratory pressure (PEEP). The extent of both mechanisms depends on the respiration aerodynamics and the corresponding pressure distribution: at end-expiration the onset of uniform pressure indicates the jet penetration length, and the level of the uniform pressure is the PEEP. The clinical problem is that adequate measurements in patients are presently impossible. In this study, the respiratory pressure distribution is therefore measured in 3D-printed anatomically correct upper-airway models of an adult and an infant. Assuming that elastic fluctuations in airway anatomy are sufficiently small, the aerodynamics in these rigid models will be very similar to the aerodynamics in patients. It appears that, at end-expiration, the jet penetrates into or slightly beyond the nasal cavity, hardly depending on cannula size or NHFT flow rate. PEEP is approximately proportional to the square of the flow rate: it can be doubled by increasing the flow rate by 40%. In the adult model, PEEP is accurately predicted by the dynamic pressure at the prong-exits, but in the infant model this method fails. During respiration, large pressure fluctuations occur when the cannula is relatively large compared to the nostrils.
AB - Two working mechanisms of Nasal High-Flow Therapy (NHFT) are washout of anatomical dead space and provision of positive end-expiratory pressure (PEEP). The extent of both mechanisms depends on the respiration aerodynamics and the corresponding pressure distribution: at end-expiration the onset of uniform pressure indicates the jet penetration length, and the level of the uniform pressure is the PEEP. The clinical problem is that adequate measurements in patients are presently impossible. In this study, the respiratory pressure distribution is therefore measured in 3D-printed anatomically correct upper-airway models of an adult and an infant. Assuming that elastic fluctuations in airway anatomy are sufficiently small, the aerodynamics in these rigid models will be very similar to the aerodynamics in patients. It appears that, at end-expiration, the jet penetrates into or slightly beyond the nasal cavity, hardly depending on cannula size or NHFT flow rate. PEEP is approximately proportional to the square of the flow rate: it can be doubled by increasing the flow rate by 40%. In the adult model, PEEP is accurately predicted by the dynamic pressure at the prong-exits, but in the infant model this method fails. During respiration, large pressure fluctuations occur when the cannula is relatively large compared to the nostrils.
KW - UT-Hybrid-D
U2 - 10.1016/j.medengphy.2022.103805
DO - 10.1016/j.medengphy.2022.103805
M3 - Article
SN - 1350-4533
VL - 104
JO - Medical engineering & physics
JF - Medical engineering & physics
M1 - 103805
ER -