Abstract :
Introduction: Classically endotracheal tube size is predicted on the bases of age based formulas but
recently ultrasound is used to estimate subglottic diameter for choosing appropriate size endotracheal tube.
Aim: To investigate the reliability of ultrasonography for determination of endotracheal tube size in
paediatric patients and its comparison with age based Motoyama formula in terms of outer diameter
determination of endotracheal tube.
Materials and Methods: After approval of institutional ethics committee 64 pediatric subjects aged
between 2-12 years belonging to American Society of Anaesthesiologists Physical Status I & II, scheduled
for surgeries under general anaesthesia with endotracheal intubation were enrolled in study. Subglottic
diameter was estimated with high resolution B-mode ultrasonography (USG). The ETT with the nearest
OD corresponding to the measured subglottic diameter was chosen.
Clinically best fit ETT size, actually used ETT size, Total time needed for USG scanning to measure the
tracheal diameter, in seconds (Ttotal): Size of ETT calculated in each patient as per age based Motayama
formula, comparison of ETT size estimated by USG and age-based Motoyama formula and that finally used
clinically was done. The data analysis was performed using IBM SPSS version 20.0 software. Quantitative
variables were expressed as meansd and compared across follow-ups using paired t-test. A p-value < 0>
is considered statistically significant.
USG predicted the appropriate ETT size (p
and uncuffed tubes. The age based formula predicted the clinically used ETT size well (p=0.58) and the
height based formula did not correlate with clinically used tube size (p=0.0002) – a statistically significant
value.
Keyword :
Ultrasound, ETT size.