X-Ray and CT Scan Based Prediction of Best Fit Tracheostomy Tube-A Pilot Study

Tracheostomy is a commonly performed intervention in patients requiring ventilatory support. The insertion of inappropriately sized tracheostomy tubes carries a risk of decannulation, tissue damage, ventilatory difficulties, premature tube change or discomfort. Currently, no clear guidelines exist in determining the most appropriate size tube. Imaging of the airway preoperatively could aid clinical judgement and reduce risk. Patients included adult critical care patients who had appropriate preoperative imaging. The computed tomography scans and chest radiographs of patients were reviewed. Measurements of the airway were taken and scaled to the known internal diameter of an endotracheal tube. A four-point scoring system was developed to identify patients better suited to a non-standard sized tracheostomy tube. Data from 23 patients was analyzed using the Statistical Package for Social Sciences™ (SPSS). Four measured points on imaging corresponded to the patients' appropriate tracheostomy tube size. Appropriate tracheostomy size correlates with tracheal diameter at endotracheal tube tip (r² = 0.135), carina (r² = 0.128), midpoint of larynx to carina (r² = 0.146), bronchial diameter at the left mainstem (r² = 0.323), and intrathoracic tracheal length (r² = 0.23). Among our cohort, a score of 4 predicts the need for a larger tracheostomy tube. Simple imaging provides accurate measurement of patients' airway dimensions. Our method ensures tube size is selected according to patient airway size, and potentially reduces the risks associated with inappropriate sizing.