title: New formulae for predicting tracheal tube length.
abstract: 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.
authors.affiliation: University of Manchester Medical School, Manchester, UK.
authors.forename: Nicky
authors.initials: N
authors.lastname: Lau
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Playfor
authors.forename: Asrar
authors.initials: A
authors.lastname: Rashid
authors.forename: Muthu
authors.initials: M
authors.lastname: Dhanarass
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000465:Algorithms; D000768:Anesthesia, General; D000886:Anthropometry / Q000295:instrumentation*; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D004867:Equipment Design; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007442:Intubation, Intratracheal / Q000295:instrumentation / Q000592:standards*; D009055:Mouth / Q000033:anatomy & histology; D009666:Nose / Q000033:anatomy & histology; D012015:Reference Standards; D012044:Regression Analysis; D012189:Retrospective Studies; D014132:Trachea / Q000033:anatomy & histology