To design and test a bench model of an intraluminal optical device capable of accurately measuring airway diameter.
A fresh porcine trachea divided longitudinally and affixed to a linear translation stage was used to simulate 20 tracheal diameters (18.3-30.3 mm). Tungsten-halogen light was dispersed across the luminal surface by a diffraction grating. Determination of the wavelength of diffusely reflected light of peak intensity by spectrograph analysis then allowed for the calculation of an optical distance for each simulated tracheal diameter. The criterion standard was the distance as measured by the micrometer on the translation stage. Intraclass correlation (ICC) and Bland-Altman regression analysis (BARA) were performed between the optical and micrometer measurements.
Trachea from a newly exsanguinated pig.
The ICC showed high correlation (0.994; 95% confidence interval [CI], 0.9860.998) (P < .001); BARA showed a small mean difference between the optical and micrometer measurements (0.052 mm; 95% CI, −0.867 to 0.762 mm) and no significant trend in bias for varying diameters (r = 0.581; 95% CI, 0.187-0.814) (P = .07).
The determination of airway diameter by means of the reflection of nonionizing radiation from the luminal surface correlates closely to actual diameter as measured by a micrometer. This bench model may be used to develop a fiberoptic intraluminal probe capable of accurately profiling airway luminal diameter and shape during flexible or rigid bronchoscopy.