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Randomised trial of estimating oral endotracheal tube insertion depth in newborns using weight or vocal cord guide
  1. Irwin Gill1,
  2. Aisling Stafford1,
  3. Madeleine C Murphy1,2,
  4. Aisling R Geoghegan1,
  5. Miranda Crealey1,
  6. Eoghan Laffan3,
  7. Colm Patrick Finbarr O’Donnell1,2,4
  1. 1 Neonatal Department, National Maternity Hospital, Dublin, Ireland
  2. 2 School of Medicine, University College Dublin, Dublin, Ireland
  3. 3 Radiology Department, National Maternity Hospital, Dublin, Ireland
  4. 4 National Children’s Research Centre, Dublin, Ireland
  1. Correspondence to Professor Colm Patrick Finbarr O’Donnell, Neonatal Department, National Maternity Hospital, Holles Street, Dublin 2, Ireland; codonnell{at}


Background When intubating newborns, clinicians aim to position the endotracheal tube (ETT) tip in the midtrachea. The depth to which ETTs should be inserted is often estimated using the infant’s weight. ETTs are frequently incorrectly positioned in newborns, most often inserted too far. Using the vocal cord guide (a mark at the distal end of the ETT) to guide insertion depth has been recommended.

Objective To determine whether estimating ETT insertion depth using the vocal cord guide rather than weight results in more correctly positioned ETT tips.

Design Single-centre randomised controlled trial.

Setting Level III neonatal intensive care unit (NICU) at a university maternity hospital (National Maternity Hospital, Dublin, Ireland).

Patients Newborn infants without congenital anomalies intubated in the NICU.

Interventions Participants were randomised to have ETT insertion depth estimated using weight [insertion depth (cm) = weight (kg) +6] or vocal cord guide.

Main outcome measure Correct ETT position, that is, tip between the upper border of the first thoracic vertebra (T1) and the lower border of the second thoracic vertebra (T2) on a chest X-ray as determined by one paediatric radiologist masked to group assignment.

Results 136 participants were randomised. The proportion of correctly positioned ETTs was similar in both groups (weight 30/69 (44%) vs vocal cord guide 27/67 (40%), p=0.731). Most incorrectly positioned ETT (69/79, 87%) were too low.

Conclusion Estimating ETT insertion depth using the vocal cord guide did not result in more correctly positioned ETT tips.

Trial registration number ISRCTN39654846.

  • Neonatology
  • Clinical Procedures
  • Evidence Based Medicine
  • Intensive Care
  • Resuscitation

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  • Contributors CPFO conceived of and designed the trial, analysed the data and edited the draft manuscript. IG wrote and revised the trial manuscript and was primarily responsible for patient enrolment, trial implementation and data collection. Trial materials and data collection tools were designed by CPFO and IG. Primary outcomes were determined by EL who also reviewed the manuscript. AS was responsible for trial implementation and data collection from January 2015 onwards and reviewed the manuscript. MCM analysed data and reviewed the manuscript. ARG and MC oversaw patient enrolment, staff engagement and monitored data collection.

  • Competing interests None declared.

  • Ethics approval Research Ethics Committee, National Maternity Hospital, Dublin.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Author note This trial was registered at (ISRCTN39654846). The authors applied for registration on 3 September 2013, before the first participant was enrolled on 27 September 2013. No substantive changes were made to the original application before the trial registration number was assigned on 14 October 2013. Four participants were enrolled in this study between 27 September 2013 and 14 October 2013.

  • Presented at Presented at the European Academy of Paediatric Societies meeting in Geneva Switzerland on 24 October 2016.

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