Optimizing Oxygen Delivery by Low-Flow Nasal Cannula to Small Infants: A Bench Study

Area of Science:

• Pediatric critical care
• Respiratory physiology
• Medical device engineering

Background:

• Accurate estimation of effective oxygen concentration (FiO2) in infants receiving low-flow nasal cannula (LFNC) therapy is clinically significant but challenging.
• Existing mathematical models for predicting FiO2 rely on assumptions and may lack accuracy in pediatric populations.
• Realistic simulations are needed to better understand oxygen delivery dynamics in neonates and infants.

Purpose of the Study:

• To assess the accuracy of oxygen delivery via LFNC in infants using a mechanical breathing model.
• To evaluate the influence of various respiratory parameters on effective FiO2.
• To develop improved methods for predicting FiO2 in infants receiving LFNC.

Main Methods:

• Development of a mechanical breathing simulator replicating infant respiratory system dynamics.
• Conduction of 1200 breathing simulations with varied tidal volume (VT), inspiratory time (Ti), respiratory rate (RR), and cannula flow rates.
• Analysis of the relationship between respiratory parameters, cannula flow, and delivered FiO2.

Main Results:

• Minute ventilation (MV) emerged as the primary determinant of effective FiO2.
• Higher FiO2 was observed with lower VT and longer Ti.
• Established formulas (Benaron and Benitz, Finer) demonstrated significant under- or overestimation of effective FiO2 compared to simulation data.
• Predictive FiO2 charts were generated using cannula flow, infant weight, and RR.

Conclusions:

• Effective FiO2 delivery via LFNC is highly sensitive to VT, Ti, and RR in infants.
• Clinical limitations in measuring VT and Ti render current predictive formulas potentially inaccurate.
• Novel predictive FiO2 charts offer a practical tool for optimizing LFNC therapy using readily available clinical parameters like infant weight and RR.