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Use of the black area on the tubetip for rapid estimation of insertional depth of endotracheal tubes in neonates: a potential hazard
  1. Neonatologist
  2. Department of Pediatrics
  3. Division of Neonatology
  4. University Hospital Groningen
  5. PO Box 30001, 9700 RB Groningen
  6. Netherlands
  7. h.molendijk{at}

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    Editor—I would like to report on a premature neonate who was intubated unilaterally as a result of improper use of the black area at the endotracheal tubetip.

    At 29 weeks gestational age, a 1020 g boy was born by emergency caesarean section to a mother who presented with preeclampsia. He was intubated immediately for signs of severe respiratory distress with a 3.0 mm ID tube via the nasotracheal route by the resident on call. The black area of the tube was inserted full length through the vocal cords with the upper rim positioned at the level of the vocal cords. Breath sounds were equally distributed on auscultation. The tube was fixated with adhesive tape at the 10 cm mark at the nose. A thoracicx ray revealed that the tubetip was located in the entrance of the right main stem bronchus. The tube was withdrawn 1.5 cm and refixated at 8.5 cm at the nose, after which exogenous surfactant was instilled for treatment of grade 3 idiopathic respiratory distress syndrome. The ensuing clinical course was uneventful and the infant was discharged with signs of mild bronchopulmonary dysplasia several weeks later.

    During the evaluation of this incident it was found that the resident who intubated had been taught at another institution that a position of the upper rim of the black area at the level of the vocal cords would ensure a proper insertional depth. However, the tubes at this other institution were produced by a different manufacturer. This prompted us to measure the actual length of the black area on the neonatal size endotracheal tubes of four major manufacturers. As shown in table 1, the length of the black area varies among tubes from different manufacturers. One manufacturer has adjusted the length of the black area to the size of the patients for which a particular tube size is indicated. The others added a black area of a certain length merely to allow for rapid visualisation of the tube in the oropharyngeal space during the intubation procedure. Indeed, the black area of the tubes that are in use at our institution have a fixed length of 30 mm, regardless of tube size and, thus, patient size. The distance from the vocal cords to the carina of a neonate of 1000 g is approximately 30 mm.1 This explains the endobronchial position after full length insertion of the black area of the endotracheal tube through the vocal cords in our patient. The equal distribution of breath sounds that was used in this case to determine the correct tube position has been shown to be an unreliable parameter for this purpose in neonates.2

    Table 1

    Length of black area at the tubetip of endotracheal tubes for neonatal use as produced by four major manufacturers

    In conclusion, this report illustrates that caution is required in the use of the black area at the tubetip for rapid estimation of insertional depth of endotracheal tubes in neonates.


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