PEEP Generated by High-Flow Nasal Cannula in a Pediatric Model

Area of Science:

• Pediatric Critical Care
• Respiratory Physiology
• Medical Device Engineering

Background:

• High-flow nasal cannulas (HFNC) are increasingly utilized in pediatric critical care.
• HFNCs may reduce work of breathing by diminishing airway dead space or generating positive end-expiratory pressure (PEEP).
• Limited data exist on PEEP delivered by commonly used HFNC flows (8-50 L/min) in pediatric patients.

Purpose of the Study:

• To assess the PEEP generated by HFNCs across various flows and air leak conditions in pediatric upper-airway models.
• To investigate the impact of different nasal cannula interfaces and simulated patient lung mechanics on PEEP delivery.

Main Methods:

• Utilized 3D-printed pediatric upper-airway models with five distinct nares.
• Connected models to a lung simulator and delivered age-specific HFNC flows (6-60 L/min).
• Measured airway pressure under varying air leak conditions (25%, 50%, 75%) to simulate open-mouth breathing.

Main Results:

• HFNC flows of 6-60 L/min generated PEEP levels ranging from 1.2 to 36 cm H2O.
• Increasing HFNC flow and decreasing air leak significantly increased delivered PEEP (P < .001).
• Lung mechanics simulating different pediatric ages resulted in varied PEEP levels.

Conclusions:

• HFNCs deliver variable PEEP at the alveolar level within the 6-60 L/min flow range.
• Higher flows and reduced air leaks enhance PEEP generation by HFNCs.
• Differences in nasal interfaces and model weights influenced PEEP levels, highlighting the importance of cannula fit.