Estimation of the length of nasotracheal tube to be introduced in children

Comparison of four formulas for nasotracheal tube length estimation in pediatric patients: an observational study

BACKGROUND

Correct endotracheal intubation results in better ventilation, prevents hypoxia and its possible damages, such as brain injury, and minimizes attempts for re-intubation. Up to now, several formulas have been published to estimate nasotracheal intubation tube length. This study aims to compare the accuracy of different suggested formulas to find the one that better estimates the tube insertion distance.

METHODS

This cross-sectional retrospective study was carried out in 102 (51 female, 51 male) children who underwent cardiac surgery under general anesthesia. Inclusion criteria were correct nasotracheal intubation according to the postintubation chest X-ray (CXR). The estimated tracheal tube length was calculated by four different formulas. Pearson...s correlation coefficient was used to find the correlations between the estimated length of each formula and the correct nasotracheal tube length. Also, linear regression was used to obtain a formula to estimate nasotracheal tube length by weight, height, and age.

RESULTS

The formula L=3*tube size+2 had the best correlation with tube length (r ...=...0.81, Confidence Interval: 0.732...0.878, p-value < 0.001). Among demographic variables, height had the highest correlation coefficient with the tube length (r...=...0.83, Confidence Interval: 0.788...0.802, p-value < 0.001). Therefore, considering the height as an independent variable and tube length as a dependent variable, using linear regression, the following formula was achieved for determining tube length: nasotracheal tube length...=...0.1*Height+7.

CONCLUSIONS

The formula L=3*tube size+2 and the new suggested formula in this study can be used to estimate nasotracheal tube length in children under 4 years old. However, these formulas are only guides and require confirmation by auscultation and CXR.

A Bedside Equation to Estimate Endotracheal Tube Length for Infants

OBJECTIVE

To develop a bedside equation that can be used to estimate the ideal oral and nasal endotracheal tube (ETT) length for children younger than 1 year of age.

STUDY DESIGN

Retrospective database analysis of 735 children younger than 1 year of age admitted to pediatric intensive care at Evelina London Children's Hospital from June 1, 2019, through August 31, 2021. ETT positions were determined by tube-tip superimposition over vertebral body on postintubation chest radiograph by trained medical students and pediatric radiologists with bedside assessment of ETT length at nostril or lip as recorded electronically by nursing staff.

RESULTS

The position of 1176 ETTs were evaluated, of which 784 (66%) were nasal and 392 (33%) were oral. After averaging length to account for multiple intubation events per patient, 281 (39%) nasal tubes and 105 (28%) oral tubes were found to be positioned optimally at T2. Using weight was superior to age or corrected age at estimating ETT length. Regression analysis revealed that optimal (T2) positioning of oral ETTs occurs at a length of (weight2+8) cm and in nasal ETTs at (weight2+9.5) cm with a mean absolute prediction error of 5%. The formulae did not require adjustments for those with comorbidities or prematurity.

CONCLUSIONS

The optimal insertion length of ETTs placed both orally and nasally in children up to 1 year of age can be estimated with appropriate accuracy by a simple bedside formula using weight as the only variable.

A new formula to predict the size and insertion depth of cuffed nasotracheal tube in children receiving dental surgery: a retrospective study

This retrospective study aimed to develop a new formula for selecting the appropriate size and determining the depth of the cuffed nasotracheal intubation (NTI) for a cuffed endotracheal tube (cETT) in pediatric patients undergoing dental surgery. In addition, the clinical data on cETT (i.e., the size and depth of insertion) was compared with those calculated with age-based formulas to evaluate their correlation. A total number of 684 patients who received NTI were enrolled (healthy group, n = 607; special-need group, n = 77). The ETT size used in real-world scenarios was smaller (i.e., about 0.5 and 0.94 mm) than the age-based formula, while the ETT depth was greater (i.e., about 1.5 cm) than the age-based formula in both groups. In the healthy group, age, gender, and body weight were identified as predictors of ETT size and depth through multiple linear regression analysis, while only age and body weight were predictors in the special-needs group. New formulas were developed based on these findings, with ETT size = 3.98 + 0.052 × age + 0.048 × gender (male = 1, female = 0) + 0.023 × body weight (kg) and ETT depth = 15.1 + 0.43 × age + 0.300 × gender (male = 1, female = 0) + 0.007 × body weight (kg). The new formula could be useful for both healthy and special-need pediatric populations undergoing dental procedures.

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.

Shallow nasal RAE tube depth after head and neck surgery: association with preoperative and intraoperative factors

PURPOSE

To evaluate risk factors associated with improper postoperative nasal Ring-Adair-Elwyn (RAE) tube depth.

METHODS

We retrospectively enrolled 133 adult patients who were admitted to the intensive care unit (ICU) with the nasal RAE tube after head and neck surgery. Postoperative chest radiography was performed to confirm nasal RAE tube depth immediately after the patient was admitted to the ICU. Proper tube depth was defined as the tube tip between 2 and 7 cm above the carina. The patients were divided into the proper-depth group (78 patients) and the improper-depth group (55 patients). Patients' characteristics were collected. The risk factors for improper postoperative tube depth were assessed using logistic regression analysis.

MAIN RESULTS

All patients who showed improper tube depth had a shallow tube depth (the tube tip > 7 cm above the carina). Multivariable analysis revealed that tall stature [odds ratio (OR) 1.16; 95% confidence interval (CI) 1.08-1.25; P < 0.001], prolonged anesthesia duration (OR 1.16; 95% CI 1.02-1.32; P = 0.026), and right-sided surgical field as compared to the left (OR 0.36; 95% CI 0.14-0.93; P = 0.034) or median field (OR 0.25; 95% CI 0.07-0.85; P = 0.027) were risk factors associated with postoperative shallow tube depth.

CONCLUSIONS

Tall stature, prolonged anesthesia duration, and right-sided surgical field were independent risk factors for postoperative shallow nasal RAE tube depth.

Nares-to-carina distance in children: does a 'modified Morgan formula' give useful guidance during nasal intubation?

BACKGROUND

Knowledge of the normal nares-to-carina (NC) distance might prevent accidental bronchial intubation and be helpful when designing preformed endotracheal tubes (ETT).

OBJECTIVE

The aim was to measure NC distance and to examine whether a height/length-based 'modified Morgan formula' would give useful guidance for nasotracheal ETT depth positioning.

METHODS

Two groups were studied. A younger group consisted of nasally intubated postoperative patients. In these, NC distance was obtained as the sum of ETT length and the distance from the ETT tip to the carina, as measured from an anteroposterior chest X-ray. An older group consisted of children who had undergone computerized tomography (CT) examination including head, neck, and chest. In these, NC was measured directly from the CT image. The modified Morgan formula was derived from the NC vs height/length relationship.

RESULTS

Nares-to-carina distance was best predicted by a linear equation based on patient height. The equation in the younger group (1 day-8 years, n = 57) was: NC (cm) = 0.14 × height + 5.8, R(2) = 0.90, and in the older group (2.1-20 years, n = 45): NC (cm) = 0.15 × height + 3.4, R(2) = 0.93. The equation for the groups combined (n = 102) was: NC (cm) = 0.14 × height + 6.2, R(2) = 0.97. Based on the latter equation, a modified Morgan formula was identified as: ETT position at nares in cm = 0.12 × height + 5. If the ETT had been placed as calculated by this formula, the ETT tip would have been at 85 + 5% (mean ± sd) of NC distance, and the ETT tip-to-carina distance would have been 3.1 ± 1.1 cm (range 0-6.6). Bronchial intubation would not have occurred in any child, but a comparison to tracheal length measurements indicates that ETT tip position could be too proximal in some children.

CONCLUSION

The study confirms previous reports: NC distance can be well predicted from height/length. A modified Morgan formula might decrease the risk for accidental endobronchial intubation in infants and children, but ETT position need to be confirmed by auscultation or other verification.

Effect of pediatric advanced life support course on pediatric residents' intubation success

BACKGROUND

The Pediatric Advanced Life Support Program (PALS) course very important for teaching about intubation, resuscitation, shock, trauma, respiratory failure and rhythm disturbances. The aim of the present study was to evaluate the effect of the PALS course on pediatric residents' intubation success during their rotation, daytime and night-time practice in the pediatric intensive care unit (PICU).

METHODS

The study was carried out from 1 March 2005 to 28 February 2007. The study period had two parts, in that the number of attempts and successful intubations performed by pediatric residents, and the pediatric intensivist successful intubation ratio were evaluated in two different periods: before the PALS course, 1 March 2005-28 February 2006, and after the PALS course, 5 March 2006-28 February 2007. The participating residents' pediatric levels (PL) were classed as PL-1, PL-2, PL-3, PL-4, and all had first experience in the PICU at the PL-1 level. The PALS instructor was a pediatric emergency or intensive care doctor. We evaluated whether the PALS course influenced intubation success or not.

RESULTS

Sixteen residents participated in the study. The proportion of successful intubations was 110 (53.3%) and 104 (65.4%) attempts before and after the PALS course, respectively. The proportion of intubations done by intensivists decreased from 49.1% to 31.7% before and after PALS. The most frequently used endotracheal tube (ETT) internal diameter (ID) was 4.0 mm, and cuffed ETT was used 16% and 21% before and after the course, respectively. Appropriate placing of ETT tip occurred 70.4% and 82.2% of the time before and after the PALS course, respectively. Proportion of successful intubations by residents increased in all levels, except for PL-1. The most important reason for unsuccessful attempts was inappropriate patient position. Only one patient could not be intubated, and laryngeal mask airway was used in that case. During intubation, complications were broken teeth in two patients before the course, and subglottic stenosis developed in only one patient due to cuffed ETT.

CONCLUSION

Successful intubation is a life-saving intervention during resuscitation, ETT revision for extubation or obstruction for extubation or obstruction during mechanical ventilation. This skill can be developed in the PALS course and by clinical study in PICU and pediatric emergency services. The PALS course must be given to pediatric residents especially within the first year. Also, cuffed ETT can be used for infants and children.

New formulae for predicting tracheal tube length

BACKGROUND

The aim of this study was to determine the accuracy of standard techniques for estimating oral and nasal tracheal tube length in children and to devise more accurate predictive formulae that can be used at the bedside.

METHODS

Data were collected from 255 children who required tracheal intubation whilst on the Pediatric Intensive Care Unit over a period of 1 year. Age, weight, the final length of the tracheal tube and the internal diameter were documented. Patients with a tracheostomy were excluded from the study.

RESULTS

Using linear regression the following formulae best predicted final tracheal tube length. For children over 1 year of age: Insertion depth (cm) for orotracheal intubation = age/2 + 13 Insertion depth (cm) for nasotracheal intubation = age/2 + 15 For children below 1 year of age: Insertion depth of orotracheal tube (cm) = weight/2 + 8 Insertion depth of nasotracheal tube (cm) = weight/2 + 9

CONCLUSIONS

Current Advanced Paediatric Life Support guidelines underestimate the appropriate tracheal tube lengths for orotracheal intubation in children over 1 year of age. Similarly, the novel weight-based formulae for tracheal tube lengths in children below the age of 1 year proved more accurate than standard reference charts. We therefore recommend that these new formulae are prospectively evaluated.