Ideal Depth of Endotracheal Intubation at the Vocal Cord Level in Pediatric Patients Considering Racial Differences in Tracheal Length.

Tomohiro Yamamoto,Ehrenfried Schindler

doi:10.3390/jcm11030864

Tomohiro Yamamoto, Ehrenfried Schindler

Open Access

https://doi.org/10.3390/jcm11030864

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Abstract

Numerous formulas that can predict endotracheal intubation depth at the corner of the mouth or the nasal wing of patients have been reported, even though the oral and nasal cavity anatomies differ among patients. Therefore, the purpose of this study was to derive a simple and reliable formula to predict the ideal endotracheal tube insertion depth at the vocal cord level in pediatric patients. The current study was conducted as a retrospective observational study, involving 425 and 335 cardiac pediatric patients in Germany and Japan, respectively, and aimed to determine a formula for predicting tracheal length and ideal depth of endotracheal intubation at the vocal cord level in pediatric patients. The distance between the vocal cords and the carina tracheae was defined as the tracheal length, and was measured on preoperative chest radiographs obtained in the supine position. The tracheal length in cardiac pediatric patients ranged from 6 to 10% of the body height in Germany and from 7 to 11% in Japan. This study revealed racial differences in the tracheal length, that is, in the ideal depth of endotracheal intubation at the vocal cord level. This study suggests that an adequate endotracheal intubation depth can be achieved by inserting endotracheal tubes at the vocal cord level with the minimum tracheal length of each racial group in pediatric patients, for example, 6% and 7% of the body height in Europeans and Asians, respectively. If the endotracheal tube inserted with this method appears to be shallow on chest radiographs, this does not represent an increased risk of accidental extubation, due to an excessively short intubation depth, because the minimum tracheal length for each racial group is considered. That is, it is not due to the endotracheal tube insertion length, but is likely due to the tracheal length of the patient, who has a relatively long tracheal length in the racial group.

Highlights

IntroductionThe proper depth of endotracheal intubation is an important factor for airway management
Even when R2 values were evaluated for neonates alone (n = 31, male/female = 15/16), their body height showed the strongest correlation with their tracheal length; the corresponding R2 values were 0.601 for the body height and tracheal length, and 0.356 for the body weight and tracheal length
Some studies have reported that body weight is most strongly correlated with tracheal length in neonates [15,16], many reports have identified body height as the parameter most strongly correlated with tracheal length in neonates [15,16,17,18], which is consistent with the results of the current study

Summary

Introduction

The proper depth of endotracheal intubation is an important factor for airway management. Short intubation depths may result in accidental extubation and complications, such as laryngeal edema, thyroid cartilage damage, and nerve damage with cuff inflation [1]. Excessively deep intubation may result in single-lung intubation, and may lead to mechanical bronchial damage, lung injury due to hyperinflation of the ventilated lung, or atelectasis of the non-ventilated lung [2]. The safe range of endotracheal intubation depths is narrow in pediatric patients, especially small babies, including neonates and premature infants. In one of the techniques used for endotracheal intubation in pediatric patients, the endotracheal tube (ETT) is withdrawn 1–2 cm cranially from the carina tracheae, after single-lung intubation [3,4]

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