The accuracy of ultrasound to predict endotracheal tube size for pediatric patients with congenital scoliosis

BACKGROUND: Ultrasonography has been used to predict the necessary endotracheal tube (ETT) size by measuring the cricoid cartilage diameter. The aim of this study was to determine the accuracy of ultrasound to predict ETT size for pediatric patients with congenital scoliosis. METHODS: Fifty pediatric patients who underwent scoliosis surgery were included in the study. According to the position of the scoliosis, patients were divided into three groups: Group C (cervical lateral bending), Group T (thoracic scoliosis), and Group L (lumbar scoliosis). For all participants, the transverse diameter of the cricoid cartilage was measured with ultrasonography. The initial ETT size was chosen according to the measurements, then the leak test was used to determine the best-fit ETT size. The ETT size predicted by ultrasound and the best-fit ETT size were compared using Bland-Altman analysis. RESULTS: There was a strong correlation between the best-fit ETT size and the ETT size predicted by ultrasound in Group T (r = 0.93, p < 0.001) and Group L (r = 0.94, p < 0.001) and a moderate correlation in Group C (r = 0.83, p < 0.001). Bland-Altman analysis showed that the ETT size was overestimated by ultrasound in pediatric patients with cervical lateral bending (bias = 0.73 mm, precision = 0.42 mm, limit of agreement = 0.08 to 1.38 mm). CONCLUSION: Ultrasound is a reliable tool to predict ETT size for pediatric patients with thoracic or lumbar scoliosis. However, pediatric patients with cervical lateral bending will need an ETT smaller than the size predicted by ultrasonography. TRIAL REGISTRATION: Chinese Clinical Trial Registry, TRN: ChiCTR1900023408, date of registration: 05.26.2019, ‘retrospectively registered’.