DISCUSSION
FE-NIV-SPI is a safe and simple technique that can be routinely applied
under common procedural setting to detect LC in infants. The usage of
nasopharyngeal catheter to deliver continuous oxygen flow and
application of nose-closure maneuver to generate airway pressure to
expand PLS and AET lumens, allowing detailed visualization of the LC.
Hypoxia and hypoventilation are frequent complications of pediatric FE
interventions, therefore the usage of supplemental oxygen and PPV are
highly recommended.21-23 Without pneumatic stenting of
SPI, as traditional method of FE, hypopharynx, posterior larynx and
upper esophagus remain collapsed and the LC may otherwise stay
undetected. Over the past two decades, we have incorporated FE-NIV-SPI
technique as the default method to maintain oxygenation and ventilation
in our endoscopic practice. This allows us to perform many bronchoscopic
interventions that otherwise cannot be safely performed in infants with
severe asphyxia condition.13-19 If FE-NIV-SPI is
routinely applied in all FE, this review suggest that it may detect more
LC at the first laryngeal examination. Although the deeper involved
lesions, such as type IV, may still need a RE to confirm, the most
commonly types of I, II and III LC defects can be diagnosed reliable
with FE-NIV-SPI. That may allow waiving more invasive and complicated
procedures of RE, general anesthesia and radiologic examinations.
For LC, an early diagnosis is crucial for subsequent management to
prevent morbidity or mortality. Traditionally, being widely available
and easily handled, FE plays an essential role in exploring lesions that
cause airway and respiratory problems in pediatric
patients.24-26 However, FE has not been considered a
commendable tool to evaluate the posterior commissure of the larynx
where lesion as LC may fail to recognize.27 RE is more
capable and remains the gold standard for confirmation of
LC.3-7 However, there may have technical difficulties
and risky, especially in small infants who already have respiratory
distress, need transfer to operation room and receive general
anesthesia. Their short oral cavity limits in securing the RE
instrument. The review suggests that these disadvantages can be
effectively counteracted by the application of FE-NIV-SPI, especially in
type I, II and III LC.
SPI with simultaneous chin-lift help to pneumatically expand the PLS
including larynx, hypopharynx, esophageal inlet and upper esophagus. In
our prior study19 of identical setting, the SPI with
duration of 0 to 5 seconds could create linear correlated positive
pressure levels from 4.1±3.3 to 65.5±18.5 cmH2O in PLS.
When the nose was open (SPI 0 second), the intra-PLS pressure around
4.1±3.3 cmH2O, the surrounding structures were
relatively collapse included the posterior glottis space. LC may be
inadvertently overlooked as a result of redundant mucosa between
esophagus and trachea apposing each other and sealing the cleft (Figure
2a), as those seven referred infants had done FE in the traditional way.
During the SPI, the intra-PLS pressure gradually rising and sustaining
up to 60 cmH2O, which were high enough to open the
collapsed lumens of AET and the esophageal sphincter. These dynamic
changes of pressure levels could be optionally and safely controlled by
operator. The LC, if existed, could be well visualized (Figure 2b, c),
probed and dispersed with the tip of FE or forceps to assess the depth
and grading the cleft. The whole AET lumens, included trachea and
esophagus, could be detail investigated. These dynamic events allowed
for repeat and precise evaluation by FE.
This FE-NIV-SPI technique provides several advantages. 1) Oxygen
insufflation alone through the nasopharyngeal catheter can flush upper
airway dead space, as the effects of “apneic
oxygenation”,28-30 which can significantly prolong
onset of desaturation. 2) Both assist inspiration and expiration can be
achieved by simple maneuvers of nose-closure and abdomen-compression,
respectively, to provide adequate oxygenation and PPV. 3) No other
supplemental instruments such as mask, endotracheal tube, ventilation
bag, or ventilator are needed, therefore it is cost-effective, eliminate
procedural time and provide an unimpeded field for FE manipulation. 4)
In addition to the LC, other coexisted lesions such as
laryngomalacia,6 vallecular
cyst,18,I9 trachea, bronchial or esophageal
pathologies also can be detected and managed in the same FE
session.16,17 5) Furthermore, it facilitates
therapeutic interventions15-18 such as laser ablation,
balloon measurement, stent implantation and repair in cardiopulmonary
compromised children.
There are limitations in this study. 1) Although FE-NIV-SPI is easy for
detecting most type I, II, and III LC, severe type IV LC may difficult
to fully visualize and not with diagnostic certainty. Confirmatory RE is
still necessary to determine the deeper cleft length and guide the
management approach, as it remains the gold diagnostic standard. 2)
Although the technique of FE-NIV-SPI have previously been
reported,13-15 this may still be unfamiliar to many
pediatric pulmonologists. Repetitive practice of this technique may be
necessary to develop skill competency. 3) This report is from one single
institution experience and the case number may not enough to make
definitive conclusion. For this rare incidence and occult lesion of LC,
further multi-center cooperative investigations are needed to verify the
early detection with this FE-SPI technique.