Predicting Uncuffed Endotracheal Tube Size in Anesthetized Children by Ultrasonography: A Randomized Controlled Trial
Kasana Raksamani MD1, Raviwon Atisook MD1, Artid Samerchua MD2, Kattiya Manomayangkul MD2, Naiyana Aroonpruksakul MD1
Affiliation : 1 Department of Anesthesiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand 2 Department of Anesthesiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
Objective : The present study aimed to demonstrate that selecting the endotracheal tube [ETT] size using ultrasound
measurement of the subglottic diameter is a more reliable method than an age-based formula.
Materials and Methods : Ninety-three patients between 1 and 6 years old undergoing elective surgery under general anesthesia
with endotracheal intubation were randomized into 2 groups. In group F (n = 46), a modified Cole formula was used to
select the ETT size, while in group US (n = 47), ultrasound measurement of the subglottic diameter was used to select the
ETT size. The appropriate tube size was clinically determined by leakage at airway pressures of 20 to 25 cmH2O. Both
groups underwent measurement of the transverse subglottic diameter in the supine position during apnea and at inspiratory
pressures [IP] of 10 cmH2O and 20 cmH2O before intubation to examine the correlation with the outer diameter of the
appropriate ETT.
Results : The incidence of appropriate ETT size selection in group US was 37 out of 47 (78.7%), which was significantly
higher than that in group F (n = 24/46, 52.2%), (p = 0.001). A good correlation was found between the ETT size from
ultrasound measurement of the transverse subglottic diameter and the outer diameter of the final proper ETT size, with
weighted kappa of 0.59+0.06, 0.75+0.06 and 0.70+0.06 at apnea, 10 cmH2O of IP and 20 cmH2O of IP, respectively. No
complications were reported in either group during the study.
Conclusion : Ultrasound measurement of the subglottic diameter to guide the selection of ETT size yielded the appropriate
size more frequently than an age-based formula in anesthetized pediatric patients.
Keywords : Intubation, Endotracheal, Pediatrics, Ultrasonography
