Evaluation of Common Nasal Cannulas in Neonatal Noninvasive Ventilation (NIV) Using a Novel Neonatal Nasal Model

Non-invasive ventilation (NIV) may reduce intubation rates and be especially beneficial in the care of preterm infants, in addition to other care modalities. Currently, ventilators do not display the pressure at the nares but the pressure in the ventilator tubing system. There are several nasal cannulas available for use to deliver NIV. The purpose of this study was to compare the inspiratory pressure on the ventilator to the measured pressure delivered at the nares using three cannula brands (Manufacturer A, Fisher & Paykel; Manufacturer B, Neotech RAM; and Manufacturer C, Hudson RCI).

This bench study utilized a 3D printed nasal model, including nares in multiple sizes to accommodate all nasal prongs studied. The nasal adaptors were connected to neonatal test lungs, to simulate patient breathing. Multiple sizes of nasal cannulas from the three manufacturers were tested for inspiratory vs delivered pressure at the patient side of the cannula, using eight combinations of ventilator settings. Each nasal cannula was tested on six Puritan Bennett™ 980 ventilators.

The measured delivered pressure at the nares was consistently lower than the clinician-set inspiratory pressure. Across all ventilator settings, 7 of the 11 cannulas delivered significantly less pressure at the nares compared to the inspiratory ventilator pressure (p < 0.01). For each cannula, as inspiratory pressure increased, the difference between delivered and inspiratory pressures also increased. The cannula from Manufacturer B consistently demonstrated the greatest differences between set inspiratory and delivered pressures for each ventilator setting.

This study demonstrated substantial differences between ventilator inspiratory pressure and measured delivered pressure, which may have clinical significance. Being unaware of the actual airway pressure delivered to the patient may lead to erroneous adjustments to the level of ventilator pressure, which may be especially consequential to those with delicate and developing respiratory systems.