Introduction
Sustained pharyngeal inflation (SPI) is an assist positive pressure ventilation (PPV) maneuver with prolonged inspiration time while a positive and a peak inflation pressure (PIP) can be created inside the pharyngolaryngeal space (PLS). In children with a patent airway, the prolonged pressurized-air flow may actively move from the upper into the lower airways and providing the ample time and pressure gradient needed for expanding the airway lumens, alveoli and promoting gas exchange across the air-fluid interface. Traditionally, this sustained inflation is accomplished with a gas flow delivered via different devices of Ambu-facemask, bi-nasal prongs, laryngeal mask airway (LMA), or endotracheal tube (ETT).1-8 The sustained inflation has gradually become a widespread clinical practice.
“Pharyngeal oxygen with optional nose-close and abdomen-compression (PhO2-NC-AC)” is a novel model of noninvasive ventilation (NIV), without using any artificial device such as Ambu-bag, face or nasal mask, LMA, ETT, or mechanical ventilator. It has already been demonstrated to provide adequate oxygenation and ventilation to assist interventional flexible bronchoscopy (FB) in pediatric patients, even in hypoxemic children on respiratory support.9-15A prolonged duration of the action of NC indeed mimic an SPI. Theoretically, in a relatively close space like the PLS, with the setting of a continuous PhO2 flow, the ventilation effect of the SPI may create as well as increase the PIP in the PLS. Closely measuring and monitoring the level of these PIPs are clinical imperative. To our knowledge, there is no study dealing with the SPI durations and associated changes of the PIP level and image in the upper airway of PLS in pediatrics.
In this study, we use the “PhO2-NC” as a SPI technique to evaluate and compare the effect of different SPI durations on the associated changes of 1) the PIP levels generated, 2) the airway lumen images, and 3) the lesion detected which measured by FB in the PLS.