Sustained pharyngeal inflation in infant airway-Flexible bronchoscopy measurements

Abstract

Sustained pharyngeal inflation (SPI) with pharyngeal oxygen flow and nasal closure (PhO2-NC) technique create positive inflation pressure in the airway. This study measured the peak inflation pressure (PIP) levels and image changes with SPI-assisted flexible bronchoscopy (SPI-FB) and compared the effects in the pharyngeal space and mid-tracheal lumen. This prospective study enrolled 20 participants aged 6 months to 3 years. Each participant underwent sequential SPI-FB of four different durations (0, 1s, 3s, and 5s) for three cycles. We used a 3.8 mm OD flexible bronchoscope to measure and analyze PIP levels, images, and lumen dimension scores. A total of 480 data were collected. The mean (SD) age and body weight were 12.0 (11.5) months and 7.8 (7.5) kg, respectively. The mean (IQR) PIPs were 4.2 (2.0), 18.5 (6.1), 30.6 (13.5), and 46.1 (25.0) cmH2O in the pharynx and 5.0 (1.6), 17.5 (6.5), 28.0 (12.3), 46.0 (28.5) cmH2O in the mid-trachea at SPI durations of 0, 1s, 3s, and 5s, respectively. The PIP levels had a positive correlation (p <0.001) with different SPI durations in both pharynx and trachea, and were nearly identical (p = 0.695, 0.787, and 0.725 at 1s, 3s, and 5s, respectively) at the same duration except the 0 s (p = 0.015). Lumen dimension scores also significantly increased with increasing SPI durations (p <0.05) in both locations. The identified lesions significantly increased as PIP levels increased (p <0.001). Conclusion: SPI-FB using PhO2-NC with durations up to 3s is safe and informative technique that provides controllable PIP, dilates airway lumens, and benefits lesion detection in the pharyngeal space and mid-tracheal lumen.

Fig 1. Gross picture of setting circuit in sustained pharyngeal inflation assist flexible bronchoscopy.

Warm and humidified oxygen flow delivers from blender, through a tube, and links to a nasopharyngeal catheter to the pharynx; bronchoscope’s inner channel connects to a pressure gauge.

Fig 2. Technique of flexible endoscopy with sustain pharyngeal inflation support.

(a) Nose-open presents with narrow airway space; sustained inflations (nose-close) expand both upper and lower airway lumens: partial enlarged images, endoscope tip in (b) the pharynx and in (c) the trachea.

Fig 3. Algorithm of study.

Sustained pharyngeal inflation–flexible bronchoscopy (SPI–FB) measurements in each enrolled infant (total 20 infants).

Fig 4. The measured peak inflation pressure (PIP) in pharynx and mid-trachea.

The PIP levels show significant positive correlation with durations of sustained pharyngeal inflation (SPI). Nearly identical PIP levels between the pharynx and mid-trachea, except in the 0 second.

Fig 5. Changes of peak inflation pressure (PIP), lumen dimension score and associated image^a with four durations of sustained pharyngeal inflation (SPI) in pharyngeal space.

The lumen spaces are gradually expand with increasing SPI durations and PIPs, which can disclose occlude lesions. Data shows in mean (interquartile range).

Fig 6. Changes of peak inflation pressure (PIP), lumen dimension score and associated image^a with four durations of sustained pharyngeal inflation (SPI) in tracheal lumen.

The lumen spaces are gradually expand with increasing SPI durations and PIPs, which can disclose occlude lesions. Data shows in mean (interquartile range).