In children, a short trachea coupled with a narrow margin of safety makes correct placement of the endotracheal tube (ETT) difficult [1]. Incorrectly placed ETT is wrought with several complications, important among them being accidental extubation and bronchial intubation [2]. According to Matsuoka et al. 23.5% of Pediatric Intensive Care Unit (PICU) intubations had incorrect ETT depth [3]. Rivera and Tibballs showed that accidental extubations accounted for 23% of intubation-related complications among infants and children in a PICU [4]. The depth of insertion for orotracheal intubation (in cm) is traditionally calculated using equations based on age (Cole's formula, adopted by APLS) [5], weight, and height (Morgan and Steward formulae) [1]. However, given the ethnic and nutritional differences across the globe, a "one size fits all" approach for calculating the size and depth of ETT insertion may not be optimal.

In the current study published in IJP, Logia et al. assessed the depth of ETT insertion and ETT migration due to changes in head and neck position using a flexible fiber-optic bronchoscope (FOB) [6]. Based on their findings, the authors have suggested a new formula that they believe will be suitable for Indian children. The study included 76 children, from 2 to 10 y, with weights and heights ranging from 7.4 to 31 kg and 68 to 135 cm respectively. Twenty-nine had cuffed tubes while 47 had uncuffed tubes. After the first fixation with the black line at vocal cord in the neutral position, it was noted by clinical auscultation and subsequently confirmed by FOB, that 6 out of 76 children (2 uncuffed and 4 cuffed) had endobronchial/at-carina position of ETT. Within the uncuffed group, endobronchial or at carina placement was present in 2/29 (6.8%) in neutral position, 12/29 (41.37%) in flexion, and none in extension. In contrast, endobronchial or at the carina placement was seen in 4/47 (8.5%) in neutral position, 17/47 (36.17%) in flexion, and 2/47 (4.25%) in extension for cuffed tubes. The ETT tip's range of motion was measured to be 0.8 ± 0.5 cm for neutral to flexion and 1 ± 0.7 cm for neutral to extension. Except for two patients, the ETT point moved in the direction of the carina during neck flexion and away from it during neck extension. Applying the age, weight and height-based formulas, the incidence of endobronchial migration/at carina placement were 23 (30%), 36 (48%) and 36 (48%) respectively [6]. Although CT and chest radiography are considered superior for assessing the depth of ETT, their routine use is limited by the turnaround time and concerns about radiation exposure. Ultrasonography may be a vital tool, provided it is available in all operating rooms and intensive care units. As Indian children differ physically from other ethnic populations, applying the traditional equations may not be appropriate and hence the authors propose a new formula for ETT placement depth [(Age/2) + 10 cm] for them.

Logia et al. have used FOB to assess the depth of placement and migration of ETT, an area not explored by many [6]. However, their study cohort has excluded infants, a vital age group in whom the shorter tracheal lengths can cause a lot of intubation-related difficulties. The authors have also not provided clarity regarding the derivation of the new formula for ETT placement depth. Although this study sensitizes towards the utility of FOB to detect ETT depth, using this invasive tool may not be feasible for day-to-day management in PICU’s. To validate the practical applicability of this method, further studies among Indian children across all ages and ethnicities are needed.