Relationship between postural changes in pretracheal tissue depth and body mass index

Background: The most common serious complication associated with tracheostomy is unintentional displacement of the tracheostomy tube. Therefore, it is important to predict the probability of the tube displacement. Obese pretracheal soft tissue thickness related to obesity is the most likely cause of tracheal tube displacement. An increase in pretracheal tissue depth resulting from postural changes may reduce the intratracheal length of the tube and increase the risk of tube displacement. This study analyzed the relationship between postural differences in the pretracheal tissue depth and body mass index (BMI). Methods: This prospective clinical trial included 100 patients who were enrolled between June 2019 and November 2020. An ultrasound probe was used to measure the pretracheal tissue depth in neutral and extended neck positions. Neck extension was achieved by placing a pillow on the patient’s back. Differences in the pretracheal tissue depth were calculated by subtracting the extended neck depth from the neutral neck depth. The patients’ BMI were calculated using weight and height data. Results: Differences in pretracheal tissue depth were correlated with neutral depth (r = 0.721) and BMI (r = 0.436). The BMI and pretracheal tissue depth were moderately, positively, and linearly correlated (neutral position: r = 0.574, extended position: r = 0.486). Conclusions: Postural differences in the pretracheal tissue depth measured using ultrasonography are correlated with BMI and may be used to predict the risk of tracheostomy tube displacement.