New decision formulas for predicting endotracheal tube depth in children: analysis of neck CT images

New Formula for Depth of Insertion of Endotracheal Tube in Children: A Prospective Observational Study

OBJECTIVES

To assess the correct placement of endotracheal tube (ETT) by confirming it with a flexible fiberoptic bronchoscope (FOB), to propose a new formula that would be suitable for Indian children, and to assess the movement of the ETT tip during neck flexion and extension.

METHODS

A total of 76 patients were included in the study between the age of 2 and 10 y. Depth of ETT insertion was assessed using FOB. ETT migration due to changes in head and neck position was also assessed.

RESULTS

It was observed that 6 out of 76 children had endobronchial/at carina position of ETT after the initial insertion as per the black line guidance in the neutral position. While the incidence was 23, 36, and 36, respectively as per Cole, weight-, and height-based formula.

CONCLUSION

The existing formulae are not suitable for Indian children as their physical stature is different from other ethnic populations. Therefore, the authors suggest a new formula [(Age/2) + 10 cm] for depth of ETT insertion for children of the authors' geographical area.

TRIAL REGISTRATION

CTRI/2015/06/005871.

Recommendations for endotracheal tube insertion depths in children

BACKGROUND

Endotracheal tube (ETT) malposition is frequent in paediatric intubation. The current recommendations for ETT insertion depths are based on formulae that hold various limitations. This study aimed to develop age-based, weight-based and height-based curve charts and tables for ETT insertion depth recommendations in children.

METHODS

In this retrospective single-centre study, we determined the individual optimal ETT insertion depths in paediatric patients by evaluating postintubation radiographic images. Age-based, weight-based and height-based ETT insertion depth recommendations were developed using regression analysis. We compared the insertion depths predicted by the models with previously published formulae.

RESULTS

Intubations of 167 children (0-17.9 years) were analysed. Best-fit curves generated with logistic regression analysis revealed R2 values between 0.784 and 0.880. The insertion depths predicted by the models corresponded well with published age-based and height-based formulae. However, they demonstrated the unsuitability of weight-related linear formulae to predict ETT depth in children.

CONCLUSION

The recommendations developed in this study facilitate a fast and accurate determination of recommended ETT insertion depths in children. Our recommendations provide greater accuracy than previously published formulae and demonstrate that weight-related linear formulae are unsuitable for predicting ETT depth in children.

Tracheal Tube Misplacement after Emergency Intubation in Pediatric Trauma Patients: A Retrospective, Exploratory Study

Inadvertent tracheal tube misplacement and particularly endobronchial intubation are well-known complications of emergency endotracheal intubation (ETI) in pediatric trauma patients, which require repositioning of the tube to avoid impairment of gas exchange. The main aim of study was to identify the frequency of tube misplacement and associated factors of pediatric trauma patients who received ETI either by prehospital physician-staffed emergency medical service (EMS), or at emergency department (ED) admission to a single level-1 trauma center. Sixty-five patients (median age 14 years and median injury severity score 29) were included. Of these, 30 underwent helicopter EMS ETI, 29 ground EMS ETI, and 6 ED ETI. Seventeen cases (26%) of tracheal tube misplacement were recognized. After multivariable analysis, tracheal tube misplacement was independently negatively associated with body weight (OR 0.86; 95% CI, 0.76–0.99; p = 0.032) and helicopter EMS ETI (OR 0.20; 95% CI, 0.04–0.97; p = 0.036). Two of nineteen patients received tube thoracostomy due to endobronchial intubation. Mortality and length of stay were comparable in patients with misplaced tubes and correctly placed tubes. The results suggest that particularly small children require attention to avoid tracheal tube misplacement, which emphasizes the need for special training. Helicopter EMS physicians’ expertise might be beneficial in prehospital pediatric trauma patients requiring advanced airway management.

Machine learning model for predicting the optimal depth of tracheal tube insertion in pediatric patients: A retrospective cohort study

Objective

To construct a prediction model for optimal tracheal tube depth in pediatric patients using machine learning.

Methods

Pediatric patients aged <7 years who received post-operative ventilation after undergoing surgery between January 2015 and December 2018 were investigated in this retrospective study. The optimal location of the tracheal tube was defined as the median of the distance between the upper margin of the first thoracic(T1) vertebral body and the lower margin of the third thoracic(T3) vertebral body. We applied four machine learning models: random forest, elastic net, support vector machine, and artificial neural network and compared their prediction accuracy to three formula-based methods, which were based on age, height, and tracheal tube internal diameter(ID).

Results

For each method, the percentage with optimal tracheal tube depth predictions in the test set was calculated as follows: 79.0 (95% confidence interval [CI], 73.5 to 83.6) for random forest, 77.4 (95% CI, 71.8 to 82.2; P = 0.719) for elastic net, 77.0 (95% CI, 71.4 to 81.8; P = 0.486) for support vector machine, 76.6 (95% CI, 71.0 to 81.5; P = 1.0) for artificial neural network, 66.9 (95% CI, 60.9 to 72.5; P < 0.001) for the age-based formula, 58.5 (95% CI, 52.3 to 64.4; P< 0.001) for the tube ID-based formula, and 44.4 (95% CI, 38.3 to 50.6; P < 0.001) for the height-based formula.

Conclusions

In this study, the machine learning models predicted the optimal tracheal tube tip location for pediatric patients more accurately than the formula-based methods. Machine learning models using biometric variables may help clinicians make decisions regarding optimal tracheal tube depth in pediatric patients.

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.

Impact of changes in head position during head and neck surgery on the depth of tracheal tube intubation in anesthetized children

Background

The classic formula has been used to estimate the depth of tracheal tube intubation in children for decades. However, it is unclear whether this formula is applicable when the head and neck position changes intraoperatively.

Methods

We prospectively reviewed the data of 172 well-developed children aged 2–12 years (64.0% boys) who underwent head and neck surgery under general anesthesia. The distances from the tracheal carina to the endotracheal tube tip (CT), from the superior margin of the endotracheal tube tip to the vocal cord posterior commissure (CV), and from the tracheal carina to the posterior vocal commissure (TV) were measured in the sniffing position (maximum), neutral head, and maximal head flexion positions.

Results

Average CT and CV in the neutral head position were 4.33 cm and 10.4 cm, respectively. They increased to 5.43 cm and 11.3 cm, respectively, in the sniffing position, and to 3.39 cm and 9.59 cm, respectively, in the maximal flexion position (all P-values < 0.001). TV remained unchanged and was only dependent on age. After stratifying patients by age, similar results were observed with other distances. CT and CV increased by 1.099 cm and 0.909 cm, respectively, when head position changed from neutral head to sniffing position, and decreased by 0.947 cm and 0.838 cm, respectively, when head position changed from neutral head to maximal flexion.

Conclusion

Change in head position can influence the depth of tracheal tube intubation. Therefore, the estimated depth should be corrected according to the surgical head position.