QUANTITATIVE BRONCHOSCOPIC ASSESSMENT OF AIRWAY COLLAPSIBILITY IN NEWBORN LAMB TRACHEAS

To date, quantitative studies of the inherent characteristics of the d eveloping airway wall have required excision of an airway segment or s urgical creation of an isolated segment. We hypothesized that airway w all characteristics, at various collapsing pressures, and attendant ch anges in stiffness after smooth muscle stimulation could be quantitate d bronchoscopically from ah-way pressure-area relationships. Neonatal lamb tracheal segments (n = 12) were suspended over hollow mounts, in a buffer-filled chamber, and subjected to a range (0 to -4.0 kPa) of p ressures to determine wall stiffness under collapsing forces before an d after stimulation of the trachealis with methacholine. Luminal image s were recorded through a 3.6-mm flexible bronchoscope under the same conditions, subsequently corrected for distortion, and a cross-section al area was quantitated. Both pressure-volume and pressure-area relati onships detected significant changes in airway wall stiffness after me thacholine administration (p < 0.002), and the magnitude of change was similar between methods. These data suggest that quantitative flexibl e bronchoscopy can be used clinically in the intact airway to assess w all stiffness.