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.