Prediction of the midtracheal level based on external anatomical landmarks: implication of the optimal insertion depth of endotracheal tubes in pediatric patients

Preventing inadvertent Endobronchial intubation: Upper incisor to manubriosternal joint length as a predictor of airway length in children

BACKGROUND

Malpositioning of the endotracheal tube within the airway can lead to serious complications. The estimated insertion depth of the endotracheal tube should be accurate and reliable.

AIMS AND OBJECTIVES

To study whether the upper incisor-manubriosternal joint length in the extended head position can be used as a predictor of airway length to guide the depth of insertion of endotracheal tube in children and to evaluate the correlation of upper incisor-manubriosternal joint length with the upper incisor-carina length in the neutral head position, in Indian pediatric population.

MATERIALS AND METHODS

After induction of anesthesia, upper incisor-manubriosternal joint length was measured using a flexible metallic tape. Endotracheal tube was inserted and secured in the midline over the upper incisors. The degree of the maximum head extension was recorded with a goniometer, and the upper incisor-carina length was measured with the help of a fiberoptic bronchoscope.

RESULTS

Analysis revealed a positive correlation between upper incisor-carina length and upper incisor-manubriosternal joint length (R = .456, R²  = .208, P = .000) and also between upper incisor-carina length and the height of the patient (R = .528, R²  = .279, P-value .000). The degree of maximum head extension did not influence the upper incisor-carina length and the upper incisor-manubriosternal joint length relationship.

CONCLUSION

The upper incisor-carina length shows a positive correlation with the patient's upper incisor-manubriosternal joint length and the patient's standing height, while the degree of maximum head extension has no significant bearing on this relationship. The upper incisor-manubriosternal joint length can be used as a predictor of airway length and the depth of insertion of endotracheal tube in children.

Does the endotracheal tube insertion depth predicted by formulas in children have a good concordance with the ideal position observed by X-ray?

Objective

To evaluate the effectiveness of the different formulas for estimating the insertion depth of an endotracheal tube in children.

Methods

This was an observational and cross-sectional study that included children between 29 days and 2 years of age who were hospitalized in a pediatric intensive care unit and mechanically ventilated. The formulas based on height [(height/10) + 5], the inner diameter of the tube (endotracheal tube × 3), and weight (weight + 6) were evaluated to determine which of them showed better concordance with the ideal insertion depth of the endotracheal tube as evaluated by X-ray.

Results

The correlation between the height-based calculation and the ideal depth observed on X-ray was strong, with r = 0.88, p < 0.05, and a concordance correlation coefficient of 0.88; the correlation between the weight-based calculation and depth on X-ray was r = 0.75, p < 0.05, and concordance correlation coefficient 0.43; and the correlation between endotracheal tube diameter-based calculation and depth on X-ray was r = 0.80, p < 0.05, and concordance correlation coefficient 0.78. Lin’s concordance correlation analysis indicated that the measurements showed weak concordance (< 0.90).

Conclusion

The formulas that estimate the insertion depth of the endotracheal tube in children were not accurate and were discordant with the gold-standard method of X-ray evaluation. There is a need for a new method based on anthropometric variables (weight and height) and age that is effective in guiding health professionals of pediatric intensive care units at the time of intubation.

Distances from vocal cords to mid-trachea for optimizing endotracheal tubes depth markers according to gestational age

BACKGROUND

Adequate endotracheal tube positioning in preterm infants is complicated by the short length of the airway. Distal markers were designed to help with the insertion of endotracheal tubes at an appropriate depth below the vocal cords. However, those markers are not standardized between manufacturers, each tube size displays only one (sometimes 2) markers to provide information for infants of various gestational ages, and indicated distances are often too long for extremely preterm infants.

AIMS

The study aims to describe vocal cords to mid-tracheal distance for different gestational ages and determine if depth markers should be adjusted accordingly.

METHODS

Half the tracheal length added to the height of the posterior lamina of the cricoids approximates the distance between vocal cords and mid-trachea. Those dimensions were retrospectively retrieved from a database of laryngo-tracheal measurements obtained during autopsies of fetuses and newborn infants free of upper airway malformations. The equation of correlation between gestational age and distance from vocal cords to mid-trachea was used to calculate those distances for different gestational ages.

RESULTS

Data were derived from 114 patients. Vocal cords to mid-trachea distance is linearly correlated with gestational age (r = .90; distance = 2.831 + 0.6208 × gestational age). We suggest depth markers at 17.7, 19.0, 20.8, 22.7, 24.6, and 26.4 mm for gestational ages of 24, 26, 29, 32, 35, and 38 weeks, respectively, indicated by contrasting colors.

CONCLUSION

The linear relationship between laryngo-tracheal size and gestational age offers the opportunity to revise endotracheal tube depth markers for the smallest patients. Trials comparing those suggested markers with those currently in use are needed before implementation.