New Formula for Nasal Endotracheal Intubation in Extremely Low–Birth Weight Infants in the Emergency Transport Setting: The “Genoa Formula”

Published:December 15, 2020DOI:


      • Nasal endotracheal intubation is a challenging procedure in extremely low–birth weight infants.
      • This is particularly true in the acute neonatal transport setting when a prompt radiologic confirmation of the tube position is not available.
      • We propose a new weight-based equation to obtain the midtracheal position of the endotracheal tube tip for nasal intubation of extremely low–birth weight infants (the “Genoa formula”).



      The purpose of this study was to find a predictive equation for estimating the optimal nasal endotracheal tube insertion depth in extremely low–birth weight infants (ELBWs) requiring invasive ventilation in the critical care interfacility transport setting.


      We retrospectively calculated the optimal tube insertion depth in a cohort of neonates ≤ 1,000 g born at our neonatal intensive care unit and nasally intubated within the first 24 hours of life from January 2019 to May 2020.


      A total of 75 ELBW infants were included, with a median gestational age of 26.6 weeks (range, 22.1-32.6 weeks) and a median birth weight of 780 g (range, 410-990 g). The linear regression of the estimated optimal endotracheal tube insertion depth showed a good correlation when plotted against weight (R2 = 0.491); thus, a new weight-based formula was obtained.


      The proposed weight-based formula (the “Genoa formula”) may help in predicting optimal insertion depths for nasal intubation in ELBW neonates, especially when a prompt radiologic confirmation of the tube position is not available, as during neonatal critical care transport.
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