Accuracy of Age-Based Formula to Predict the Size and Depth of Cuffed Oral Preformed Endotracheal Tubes in Children Undergoing Tonsillectomy

Abstract

Objectives: To retrospectively investigate the reliability of the age-based formula, year/4 + 3.5 mm in predicting size and year/2 + 12 cm in predicting insertion depth of preformed endotracheal tubes in children and correlate these data with the body mass index. Patients and Methods: Patients were classified into 4 groups according to their nutritional status: thinness, normal weight, overweight, and obesity; we then retrospectively compared the actual size of endotracheal tube and insertion depth to the predicting age-based formula and to the respective bend-to-tip distance of the used preformed tubes. Results: Altogether, 300 patients were included. The actual endotracheal tube size corresponded with the Motoyama formula (64.7%, 90% CI: 60.0-69.1), except for thin patients, where the calculated size was too large (0.5 mm). The insertion depth could be predicted within the range of the bend-to-tip distance and age-based formula in 85.0% (90% CI: 81.3-88.0) of patients. Conclusion: Prediction of the size of cuffed preformed endotracheal tubes using the formula of Motoyama was accurate in most patients, except in thin patients (body mass index < −2 SD). The insertion depth of the tubes was mostly in the range of the age-based-formula to the bend-to-tip distance.

Adverse Tracheal Intubation Events in Critically Ill Underweight and Obese Children: Retrospective Study of the National Emergency Airway for Children Registry (2013–2020)

“…The relatively higher percentage of mainstem bronchial intubations is one potential contributor to the higher occurrence of adverse airway outcomes. This may be due in part to the use of age-based endotracheal tube placement formulas which could overestimate the depth in an underweight child (27).…”

“…Thus, appropriate interventions to minimize risk should be considered for this population, especially when other proven risk factors for adverse events have also been noted, such as younger age, significant comorbidities, including heart and/or pulmonary disease, sepsis, trauma, heart disease, or physical features of a difficult airway (34,35). It is also important to consider that age-based formulas for endotracheal tube placement depth may be less accurate in underweight patients which may have contributed to the increased mainstem bronchial intubations seen in the study (27). Strategies that have shown to decrease desaturations in pediatric patients include maximizing preoxygenation, using apneic oxygenation, and limiting duration of attempts (35)(36)(37).…”

Length of the middle finger of hand as a simple and reliable predictor of optimal size of uncuffed endotracheal tube in paediatric patients: An observational study

“…As the interest in cuffed ETTs has gained momentum, and the formulae for such tubes are different, comparison of middle finger length with such formulae would be interesting. [ 16 ]…”

Effectiveness of substantial shortening of the endotracheal tube for decreasing airway resistance and increasing tidal volume during pressure-controlled ventilation in pediatric patients: a prospective observational study

“…Patients with respiratory disease, di cult airway, or risk of malignant hyperthermia were excluded. The ETT size was determined according to the Motoyama formula: ETT inner diameter (mm) = 3.5 + patient age / 4 [11], and the cuff was adequately in ated so that respiratory gas did not leak out. The initial settings for PCV were as follows; a positive end-expiratory pressure of 5 cmH 2 O, a respiratory rate of 15/min, an inspiratory time of 1.33 s, and a driving pressure of 10 or 15 cmH 2 O.…”