Age-related changes in upper airway anatomy via ultrasonography in pediatric patients

Purpose: Ultrasonography is a portable, noninvasive tool that may be used to evaluate the upper airway. The purpose of our study was to present a systematic approach to identify salient features of the pediatric airway and determine whether ultrasonography can identify anatomical changes that occur with growth and development. Methods: We present a prospective, observational trialwhere patients included were between 1 day and 10 years of age presenting for elective surgery who had no known history of unfavorable airway pathology. We sequentially obtained 5 ultrasound views under anesthesia: (1) sagittal sternal notch viewof the trachea, (2) sagittal longitudinal viewof trachea (LT), (3) axial view at the level of the vocal cords (AVC), (4) axial view at the level of the cricoidmembrane (AC), and (5) sagittal longitudinal submental space view (SM). A broadband linear array transducer was used to identify airway structures and perform measurements. Results: Eighty-four percent of enrolled patients underwent airway imaging and were analyzed using multiple regression and Spearman correlation (p). In view 1, tracheal diameter via sagittal sternal notch view was immeasurable because of air disturbance. In the LT view, the distance from the skin to the cricothyroid membrane (LT1) did not statistically increase with age in days (P = 0.06); however, the distance from the cricoid to thyroid cartilage (LT2) did correlate to age (P < 0.001; 99% confidence interval [CI], 1.8 x 10-5, 7.7 x 10-5; p = 0.77, P = 0.001).We found a statistically significant relationship between age and the distance between the anterior and posterior commissures (AVC2; P < 0.001; 99% CI, 1.0 x 10-4, 1.7 x 10-4; p = 0.80, P < 0.001), the distance from the skin to the posterior commissure (AVC3; P < 0.001; 99% CI, 9.6 x 10-5, 2.0 x 10-4; p = 0.73, P < 0.001), the distance to the cricoid cartilage (AC; P < 0.001; 99% CI, 2.0 x 10-5, 7.7 x 10-5; p = 0.66, P < 0.001), and the distance from the tongue base to the soft palate (SM2; P < 0.001; 9% CI, 1.8 x 10-4, 3.9 x 10-4; p = 0.85, P < 0.001). There were no significant relationships between age and AVC1 (P = 0.16) and SM1 (P = 0.44). Conclusions: Airway ultrasound is a feasible tool to evaluate the pediatric airway in children younger than 10 years; however, the detection of agerelated changes of certain structures is limited to select measurements.