Abstract
Background: The fractional inspired concentration of oxygen (FiO2) provided to infants via high-flow nasal cannula (HFNC) is regulated by the air-oxygen blender and is considered stable. The effect of breathing dynamics on the effective FiO2, especially at lower HFNC flows, is unknown.
Objective: To examine the influenced of breathing dynamics on the effective FiO2 delivered to small infants via HFNC.
Methods: We performed simulations at varying target (set) FiO2 values, nasal cannula (NC) flows, and minute ventilation (MV), using a mechanical infant lung model (ventilation compartment, FiO2 sampling, upper airway model, NC, air-oxygen blender).
Results: The effective FiO2 approximated the target (set) value at HFNC flows >5 L/min, irrespective of the breathing pattern (Figure). At lower flows, however, the effective FiO2 diverges from the target value depending on MV; higher MV (higher tidal volume and/or respiratory rate) results in lower effective FiO2 (higher FiO2 bias) and vice versa. At NC flows <2 L/min the FiO2 bias becomes significant even for lower MVs.
Conclusions: The effective concentration of oxygen delivered to small infants via HFNC diverges significantly from the target FiO2 at higher MVs and/or at nasal cannula flows <2 L/min. The weaning of oxygen dependent small infants from the HFNC requires attention.
Footnotes
Cite this article as: European Respiratory Journal 2021; 58: Suppl. 65, OA3957.
This abstract was presented at the 2021 ERS International Congress, in session “Prediction of exacerbations in patients with COPD”.
This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).
- Copyright ©the authors 2021
