[Estimation of the optimal tube length : Systematic review article on published formulae for infants and children].

BACKGROUND: The correct placement of an endotracheal tube in children is essential as incorrect placement following unilateral ventilation and tube displacement may lead to far-reaching consequences, such as volutrauma and hypoxia, respectively. Different formulae referring to the correct placement of nasotracheal and orotracheal tubes have been published with reference to body weight and age.

OBJECTIVE: The aim of the present review article was to identify and compare the published formulae for estimating correct endotracheal tube placement in children with their advantages and disadvantages.

MATERIAL AND METHODS: A search in Medline and PubMed was performed to identify published formulae. Formulae for insertion depth in orotracheal and also nasotracheal intubation are discussed. The published formulae for newborns and infants are presented separately. The keywords "paediatric"/"pediatric", "anaesthesia"/"anesthesia", "anaesthesiology"/"anesthesiology", "endotracheal tube", "placement", "position", "length", "depth" and "insertion" were used to identify the formulae.

RESULTS: A total of 806 publications were found, 16 publications were identified as being relevant and 13 different formulae were identified. In the age group from 1 to 16 years old a total of 7 formulae (6 age-based formulae and one based on weight) and for newborns and infants a total of 6 formulae (4 formulae based on body weight, 1 formula based on body length and 1 formula based on gestational age) were found. All publications were subsequently assessed and classified independently by a specialist physician in anesthesiology and a specialist physician in pediatrics.

CONCLUSION: The published formulae were comparatively simply to apply but had notable limitations. Correlating the position of the endotracheal tubes with chest x-rays, the concordance analysis showed that for the age-based formulae using orotracheal as well as nasotracheal intubation and in both age groups, an accordance could only be achieved in a maximum of 81%. In the presence of a lack of alternative possibilities, only one formula based on the gestational age seemed to have an impact on estimation of correct endotracheal tube depth placement in newborns and infants. Therefore, a generally valid formula cannot be recommended without verification by auscultation or chest x-ray.