A prospective observational trial evaluating factors predictive of accurate endotracheal tube positioning in neonates and small infants

There is a high incidence of endotracheal tube malposition in neonates and small infants. Yet, verification of accurate endotracheal tube location via radiographic imaging involves radiation exposure.

of intubations in the pediatric intensive care unit resulted in improper ETT placement. 6 Methods to confirm the ETT position like end-tidal carbon dioxide monitoring and ultrasonographic technique can reliably detect esophageal intubation but cannot verify the position of the ETT within the tracheobronchial tree. 7,8 Therefore, the current gold standard to confirm the correct ETT position is chest radiography. 9 However, radiographic imaging should be limited in neonates because of radiation exposure. 10 Several studies have demonstrated the influence of demographic and clinical parameters such as the physician's experience or the age and weight of the patient on the likelihood to achieve accurate ETT position. 11,12 However, these surveys did not evaluate the predictive value of the combination of multiple variables, and neonates, especially preterm infants, were rarely included.
The purpose of this investigation was to evaluate the likelihood of accurate ETT position in neonates and small infants according to demographic and clinical parameters.

| Study design and subjects
This was a prospective single-center study. Our population consisted of term and preterm neonates and small infants who underwent endotracheal intubation either in the delivery room or in the NICU at our tertiary perinatal center between January 2018 and November

2019.
Patients were nasally intubated with an uncuffed endotracheal tube (Vygon) via direct laryngoscopy (Dahlhausen) with a size 0 or 1 Miller blade (Dahlhausen) and a Magill forceps (Sohngen) to guide the tube trough the vocal cords. There is an institutional consent in our department that the ideal ETT placement in neonates is a mid-tracheal tip position. An adhesive tape (BSN Medical) was used for nasal ETT fixation. After intubation and ETT fixation, the physician who had performed the intubation completed the first part of a data collecting form prior to the radiographic control. Patient demographics recorded were gender, weight at intubation, and postnatal age, and the presence of malformations. Further information retrieved included acuteness of intubation (elective/urgent/emergency), whether the patient was previously intubated and, if applicable, the last ETT position, experience of the physician (numbers of neonatal intubations performed <10/10-50/50-100/>100), view obtained by laryngoscopy (Cormack-Lehane 1/2/3/4), 13  The study protocol was approved by the ethics committee of the local medical chamber of Hamburg.

| Statistical analysis
Statistical analysis was performed using spss Version 26 software (IBM). Data on neonatal demographics were expressed as median and range for continuous variables and as counts and percentages for categorical variables.
Relationships between the accurateness of ETT position and examined categorical variables, as well as among categorical variables, were examined using χ2 and Fisher's exact tests. Results are presented as odds ratios (OR) with 95% confidence interval (CI).
Two-tailed P-values <.05 were considered significant. Relationships between independent variables and outcomes were examined by

What is already known about the topic
• Precise positioning of the endotracheal tube (ETT) is essential to reduce the incidence of ventilation-associated complications in neonates. So far, radiographic imaging is the only technique that can reliably confirm accurate ETT position.

What new information this study adds
• Various analyzed demographic and clinical parameters were not reliable to predict correct ETT position in neonates and small infants.
• Male sex was the only variable that significantly correlated with an accurate ETT position. mixed-effects logistic regression (SPSS routine GENLINMIXED) to account for cluster effects, considering fixed effects of the respective independent variables and random intercepts for individual patients. 95% CI: 1.7, 9.3; P < .001). Moreover, a better view of the glottis also led to a more frequent indication of being "very certain" regarding a precise ETT position (OR 3.2; 95% CI: 1.7, 6.5; P < .001).Also, CL1 visibility was significantly more often attained in neonates >1500 g compared to <1500 g (OR 3.0; 95% CI: 1.5, 5.7; P < .001).

| D ISCUSS I ON
While several studies have investigated formula to calculate accurate ETT depth and imaging techniques to verify the ETT position, there has been little research aiming to identify parameters that correlate with a precise ETT position in neonates. In this prospective study, an accurate tube position was attained in 71.4% of the intubations. This observation is consistent with other studies reporting an incidence of ETT malposition among patients <1 year of 35%. 7,15 As expected, experienced physicians were more likely to intubate neonates <1500 g compared to less experienced colleagues (OR 4.1; 95% CI: 2.0, 8.2; P < .001). However, even when adjusted for the weight of the infant, intubation experience remained noncorrelated with the accurate ETT position, which is consistent with previous studies demonstrating that training of the proceduralist is not associated with tube misplacement. 12 Nevertheless, physicians with a lower level of experience (<50 intubations) were less likely to be "very certain" regarding the estimation of precise ETT position compared to more experienced colleagues (OR 3.8; 95% CI: 10 years and identified female sex as a risk factor for low misplacement. 12 The shorter distance between lips and carina in women compared to men was hypothesized to be the reason for more common endobronchial intubation among female adults in earlier studies. 21,22 But previous studies of pediatric airways using computed tomography have revealed no difference in the length of the trachea between boys and girls of equal height. 23 Thus, these sex-related differences in neonates and children merit further investigation to explore the underlying mechanism.
In conclusion, this study substantiates the inalienability of postintubation imaging for the verification of ETT placement in neonates and small infants. To diminish ionizing radiation applied by radiographic imaging, several studies have evaluated the diagnostic value of ultrasonography for the assessment of endotracheal tube placement both in adults and in children. 24 However, although bedside ultrasonography can accurately distinguish esophageal from tracheal intubation, it provides limited ability to verify the accurate depth of ETT insertion. 7,25 There were several limitations to our study. This study was a single-center analysis, intubation procedure, and definition of appropriate ETT position may differ elsewhere. We did not report end-tidal carbon dioxide monitoring as this method has proven high sensitivity and specificity of detecting esophageal intubations, but it is incapable of identifying tube misplacement within the tracheobronchial tree. 8 ETT position might have unintentionally been altered during fixation prior to radiographic control; this was observed in two cases.

ACK N OWLED G M ENTS
Open access funding enabled and organized by Projekt DEAL.

CO N FLI C T O F I NTE R E S T
No conflict of interest.