Novel Formula for Calculation of the Optimal Insertion Depth for Cuffed Endotracheal Tubes in Pediatric Major Surgery

Abstract

Background: Accurate determination of the optimal insertion depth of a pediatric endotracheal tube (ETT) is quite important. The aim of this study was to create an easily available formula that can be used to determine the optimal insertion depth for a cuffed ETT even without depth marking with clear definitions of the upper and lower limits for the tip of ETT in the trachea in clinical practice. Methods: Eighty children under 12 years of age were enrolled. The depth marking of the cuffed ETT was placed at the vocal cords and both lungs were then auscultated using a stethoscope. The upper limit was radiographically defined as the position of the tip of the cuffed ETT being between the clavicles. The lower limit was defined as a distance of 5 mm above the carina. The relationship between the insertion depth and patient characteristics was analyzed to create a formula for optimal ETT insertion depth. Results: Sixty-nine ETTs were optimally placed in the trachea. There were good correlations between the optimal insertion depth of ETTs and patients characteristics (height (R = 0.92); BSA (R = 0.92); weight (R = 0.91); age (R = 0.88)). Using these patient characteristics, we created the following three formulas for calculation of the optimal insertion depth for pediatric cuffed ETTs: insertion depth (cm) = height (cm)/11 + 5.5, weight (kg)/3 + 9.5 or 11 + 3/4 × age (years). The rates of appropriate tube placement of both pediatric cuffed ETTs were 87.5% (Hi-Contour) and 85.0% (Microcuff). Conclusions: Our formula and graphs may be easy to determine the optimal insertion depth of cuffed ETT even without depth marking in clinical practice.

Accuracy of predictive equations in guiding tracheal intubation depth in children: A prospective study

“…However, they used cuffed ETTs and had different numeric variables in the formulae. 3 The incidence of distal intubation was found to be 74% in our study group with an accurate placement seen only in 13 patients. The subgroup analysis in the present study showed 30% appropriate depth in age group of 1-2 years, 42.8% in 2-3 years, and 6.25% in 3-4 years subgroup.…”

“…1,2 Various formulae have been studied for determining the accurate ETT depth in children. [3][4][5][6] These formulas are either complex 4 or have suboptimal accuracy. 5,6 Age-, 7 weight-, 8 and height-based 9 formulae have been frequently used to predict the optimum ETT depth in children.…”