Results
In these 20 studied infants (Table 1), the mean (SD) age was 11.6 (9.1) months and the mean (SD) body weight was 6. 8 (2.4) kg. There were 40 sets of measured data. The mean (SD) operative time of this SPI study was 5.7 (1.2) minutes.
Table 2 presents the details of the intrapharyngeal PIP, lumen expansion scores, locations and number of detected lesions on these four SPI modes. In the collected 40 sets of measurements, the mean (SD) PIP in the pharynx were 4.1 (3.3), 21.9 (7.0), 42.2 (12.3) and 65.5 (18.5) cmH2O at SPI duration of 0, 1, 3 and 5 seconds, respectively. As shows in the Figure 2, there is positive and significant (p<0.001) linear increase in PIP levels with SPI duration from 0 through 5 seconds. In these changes of image sequences, there was progressive space expansion and significant greater lumen expansion scores (p<0.001) in all locations of the PLS.
Those pressure-sensitive dynamical lesions, such as pharyngomalacia, laryngeal malacia, laryngeal cleft, glottic malacia, etc., which might be overlooked with a low PIP level of short duration SPI. But after adequate lumen expansion with a high PIP level, definite diagnosis could be achieved. Significantly higher number of lesions could be detected with higher PIP levels (p=0.004). With the SPI of 5 seconds, the highest PIP, and lumen expansion score were achieved, and FB identified the most number of lesion (p<0.001).
The corresponding levels of PIP, expansion scores, images of each SPI mode of pharyngeal and laryngeal lesion were illustrated in the Figure 3 and Figure 4, respectively. On the same row, all four images were taken at similar location of same infant but with different PIP levels generated by different SPI durations. In these changes of image sequences, there was a progressive and significant space expansion and greater lumen dimension scores in all locations of the PLS, especially with existing airway pathologic lesions such as pharyngomalacia, uvular cyst, vallecular cyst, etc. During FB assessment, these created lumen expansions also facilitated accurate and comprehensive evaluation of lesions which were not visible in the low PIP levels but became apparent with the high PIP levels of longer SPI duration.
All these SPI studies were successfully completed. There was no any study-related complication such as upper airway bleeding, subcutaneous emphysema, pneumothorax, desaturation (<90%) or bradycardia (<100 beat/min).