Measurement of the Endotracheal Tube Diameter Using Computed Tomography Images for Pediatric Patients: Comparison with Classic Formulas

Objective: In this retrospective study, we aimed to evaluate the compatibility of endotracheal tube (ETT) size used during surgery with tracheal diameter measured by computed tomography(CT) and classic formulas in children who underwent CT imaging preoperatively due to surgical indications. Methods: The study included preoperatively CT scanned, 0-3 year-old patients who were operated due to congenital heart diseases between June 1-October 1, 2018.Using the CT scans, transverse and anteroposterior tracheal diameters were measured from the subglottic level. As these diameters reflect the external diameter of the ETT, the inner diameter-which corresponds the ETT size-was calculated using a correction formula. Besides, Cole’s formula was used to calculate the ETT size for each child, and the tube sizes used during surgeries were obtained from anesthesia charts.ETT sizes were compared. Results: 43 patients (22 girls [51.2%],21 boys [48.8%]) were included.The mean age was 10.5±9.6 months. 18 patients (41.9%) had cyanotic, 25 patients (58.1%) had acyanotic heart disease.Mean corrected transverse and anteroposterior tracheal diameters at CT images were 4.35±0.69mm and 4.30±0.71 mm, respectively. The mean diameter calculated by Cole’s formula was 4.22±0.20 mm. The mean tube size used during surgeries was 4.37±0.60 mm. There was no statistically significant difference between the tube sizes used during the surgeries and the corrected transverse tracheal diameters from CT measurements (p>0.05). But the tube sizes used during the surgeries found significantly larger than the diameters obtained by Cole’s formula (p<0.05). Conclusion: In 0-3 years of age pediatric patients who undergo a congenital heart surgery,corrected tracheal transverse diameter measured by CT is more effective,reliable and less invasive than classic formulas for determining appropriate ETT size