Background: Nasal-tragus length (NTL) estimates of endotracheal tube (ETT) depth are replacing weight-based estimates for ETT depth in neonates requiring endotracheal intubation. Existing neonatal simulators were designed before interest in using the NTL and may lack fidelity in this measurement.
Research Question: To evaluate the accuracy of 2 adjusted NTL formulas and the neonatal resuscitation program (NRP) weight based ETT depth chart in predicting proper endotracheal tube insertion depth in a cohort of neonatal simulators.
Methodology: This study followed a cross-sectional, observational cohort study design. Ten neonatal task trainers and manikins were tested. Simulators were intubated by direct laryngoscopy with an uncuffed ETT such that the distal tip reference double lines were aligned with the true vocal cords, indicating appropriate placemen. Endotracheal tube depth was measured at the gum line. Tracheal lengths were measured from the vocal cords to the bifurcation of the trachea for each simulator that had a bifurcation. For each simulator the correct depth measured via direct laryngoscopy and the recommended depth from the weight based chart were compared with the predicted depth based on the adjusted NTL: NTL +1cm and NTL +0.5cm.
Results: The adjusted NTL + 0.5cm formula incorrectly predicts the depth needed for proper placement of ETT in 100% of tested simulators, the NTL + 1cm formula incorrectly estimates the depth needed in 63% of simulators, and the weight based chart incorrectly estimates depth in 75% of test simulators.
Discussion/Conclusions: The majority of neonatal resuscitation simulations lacked physical and functional fidelity in regards to ETT insertion depth. The formula NTL + 1cm outperforms the NTL+0.5cm formula and the NRP weight-based chart, but still resulted in endotracheal tube misplacement in the majority of neonatal simulators. The SimNewB™, Newborn Anne™, Premie Blue™ and Premie Anne™ manikins had the highest levels of physical and functional fidelity of the neonatal simulators evaluated.