Introduction
Sustained pharyngeal inflation (SPI) is an assist positive pressure ventilation (PPV) maneuver with prolonged inspiration time while peak inflation pressure (PIP) can be created inside the pharyngolaryngeal space (PLS). In children with a normal patent airway, the pressurized-air flow may actively move from upper into the lower airways and providing the ample time and pressure gradient needed for expand the airway lumens, alveoli and gas exchange across the air-fluid interface. Traditionally, this kind of sustained inflation (SI) is accomplished with a gas flow that delivers via different devices of Ambu-facemask, bi-nasal prongs, laryngeal mask airway (LMA), or endotracheal tube (ETT).1-8 This SI has gradually become a widespread clinical practice. Theoretically, in a relative close space like the PLS, the levels of created PIP may positively correlate to the durations of SPI.
“Pharyngeal oxygen with optional close-nose and abdomen-compression (PhO2-NC-AC)” is a novel model of noninvasive ventilation (NIV), without using any artificial device such as mask, LMA or ETT. Which has already demonstrated able to provides adequate oxygenation and ventilation to assist interventional flexible bronchoscopy (FB) in children, even in severe asphyxiated status.9-15 In the setting of PhO2, the ventilation effect of the “nose-close (NC)” can also create PIP in the PLS. A prolonged duration of the NC indeed provides a SPI. Closely measuring and monitoring the levels of these created PIPs are clinical imperative. However, to our knowledge, there is no study deal with the SPI durations and associated changes of PIP and image in upper airway of PLS in pediatrics.
In this study, we use the “PhO2-NC” as a SPI technique to evaluate and compare the different durations effect on 1) the created PIP levels in PLS; and 2) the associated changes of airway image measuring by FB.