Trial Objective: To determine whether estimating ETT insertion depth using gestational age
chart rather than nasal-tragus length method results in more correctly positioned ETT tips.
Setting: The neonates will be recruited from multiple tertiary-level neonatal intensive care
units in Saudi Arabia. A neonate can participate in more than one clinical trial, depending
on the interventions being given. Parallel run trials will be discussed between the chief and
local principal investigators whether or not joint recruitment is feasible to both parties.
Informed Consent: We will obtain written consent after the parents have been given a full
verbal explanation and written description. We will explain to the parents in their own
native language. We will use a hospital-based adult interpreter wherein required. We will
obtain deferred consent (after initial verbal assent) where prior consent is not feasible as
the study does not involve additional risk or investigations to the participants, and the
interventions are otherwise considered as standard practice recommendations by the NRP.
Data Safety Monitoring Board: Any unexpected serious events (death, any life-threatening
event, any event that will prolong the hospitalization or any event that will result in
disability) will be reported to the data safety monitoring committee. The trial steering
committee will receive recommendations from the data safety monitoring board if the trial
requires early termination following the interim data analyses and evidence from relevant
studies. The following measures were agreed to consider stopping the trial, wholly or partly
(subgroups), after an interim analysis, that will be done after recruiting 200 participants.
An absolute difference of greater than or equal to 25% in the primary outcome between
the study groups.
An absolute difference of less than 5% in the primary outcome between the study groups.
A rate of less than 20% in the primary outcome in either of the groups.
Sample Size: Our unpublished data showed using the nasal-tragus length method results in 35%
of correctly positioned ETT tips in term and preterm infants. The data is similar to the
randomized and non-randomized studies that showed an accuracy between 32 and 37 percent using
the nasal-tragus length method. With 90% power and two-sided 5% significance, to detect an
absolute increase in optimally positioned ETT tips of 15%, we will require 454 participants.
We calculated sample size using nQuery Advisor Sample Size Calculator version 8.3.0.0.
Statistical Analysis: We will analyze the data based on the intention-to-treat principle.
Univariate analyses will be performed to compare baseline demographic factors between the two
groups. A mean with standard deviation (normal data) or median with interquartile range
(skewed data) will be obtained for continuous variables and numbers and percentages for
categorical variables. Independent T-test (normal data) or Mann Whitney U test (skewed data)
for continuous variables and chi-square test (or Fisher's exact test as appropriate) for
categorical variables will be used for analyses between the groups. Statistical Analysis
Software version 9.4 will be used for the conduct of all analyses.
Analysis of primary outcome: Adjusted risk ratios of a successful outcome will be calculated
along with 95% confidence intervals. Adjusted ratios will be determined by way of
multivariable logistic regression analysis, including co-variates deemed biologically to have
an influence on the primary outcome (gestational age, small for gestational age, and center).
Principles of best model practices will be followed (including assessment of collinearity
amongst included variables) as well as the determination of the predictive ability of the
model using area under the curve.
Analysis of secondary outcomes: Similar analyses as above will be performed for all secondary
outcomes that are categorical variables. The risk ratios of secondary outcomes mortality,
oxygen therapy at 28 days, pneumothorax, and bronchopulmonary dysplasia will be adjusted
based on the following variables: gestational age, male sex, small for gestational age,
maternal hypertension, chorioamnionitis, antenatal steroids, and center if the P-value is
less than 0.25 on univariate analysis.