Discussion
This study found that simulator-based training for identification of
endotracheal tube placement was efficacious in training novice users
with high sensitivity and specificity. Our study showed POCUS to be an
accurate and rapid method to detect correct position of the endotracheal
tube (3.0 (IQR 3.0-4.0) seconds).
The majority of intubations were for emergent causes including
respiratory failure, surfactant administration, and hemodynamic
compromise; similar to those reported by Foglia et al. in
2019.26 Another study also listed reasons for ETT
intubations such as prematurity (57.8%), respiratory failure (24.3%),
life-threatening apneas (13.4%), and re-intubation after accidental
displacement of ETT (4.5%).27
Several methods are considered as standard-of-care methods for ETT
position confirmation including bilateral chest auscultation,
capnography, and chest radiography. Studies in adults have demonstrated
disposable CO2 detectors to be highly sensitive and
specific for confirmation of ETT placement and reported a sensitivity
and specificity of 91% and 100% when compared to clinical
examination.27 Likewise, POCUS sensitivity and
specificity for identification of an ETT was reported to be 0.98 (95%
CI 0.97 to 0.99) and 0.98 (95% CI 0.95 to 0.99), respectively in a
meta-analysis of f 323 adult intubations . They recorded a sensitivity
of 91% and specificity of 97% of POCUS compared to standard
methods.28 Similarly another meta-analysis reported
sensitivities of 93-98% and specificities of 97-98% for
POCUS.29
In contrast to adult POCUS, the use of this modality for ETT placement
is somewhat scarce in pediatrics. Chou et al. in 2013 reported a
sensitivity and specificity of 100% in children that underwent
resuscitation and intubation.30 In our study, the
sensitivity and specificity compared to standard care was 99.7% and
91.7%, respectively.
The time it takes to confirm ETT placement is critical regardless of the
method chosen. Chest auscultation can be unreliable in a noisy
environment during resuscitation and takes approximately 77 seconds to
appreciate audible breath sounds.31 However, in our
study, we recorded a short time of only 6.0 seconds with the
auscultation method. The possible reasons could be the rigorous
mandatory NRP training and certification that the health care providers
in NICU undergo with repeated refresher trainings, leading to excellence
in competency.
Capnography, although a reliable method with high
sensitivity10 can depict false negative results in
conditions with low cardiac output, inadequate pressure to inflate the
lungs,10,32 and presence of secretions in
ETT.33 However, it is a rapid method and studies have
reported the time for capnography confirmation as 1.6 seconds (SD +/-
2.4).31 In a study by Aziz et al., the time required
to confirm ETT position via capnography was 6 to 12
seconds.27 We reported a similar time of 3 seconds
(IQR 3.0-4.0).
Use of POCUS is gradually gaining popularity with its rapid assessment
and ease of interpretation in infants and newborns. It does not
interfere during chest compression and is not affected by environmental
noise and cardiac output.30 The average time required
for POCUS used in emergency situations by physicians and
anesthesiologists reported in literature is 9
seconds.29 Several studies have also measured the time
to perform transtracheal ultrasound in emergent situations with a wide
range from 5-45 seconds,15,28,34,35 while few studies
have shown time to ultrasound to be shorter than
capnography.28,36,37 However, our study showed no
difference in interpretation time with both modalities.
This is the first study of its kind to assess diagnostic accuracy of
POCUS for endotracheal tube placement in a neonatal population in the
country. It was a prospective design with the largest sample size of
newborns to date. We did not only measure the accuracy of POCUS with
standard-of-care methods, but also measured the time to interpretation
for each method in a real-time scenario. Moreover, POCUS and
standard-of-care methods were interpreted independent of each other,
thus minimizing the risk of bias.
The study has some potential limitations. In our setting we did not have
each of the three standard-of-care methods for all intubations and hence
the analysis was done by composite of at least two current methods. In
addition, this was a single-centre study and hence the results may not
be generalized.
Point of care ultrasound has various advantages and its clinical
prevalence is increasing in adults and older children. Many of these
applications and benefits can be translated to a neonatal population.
This may improve resuscitation by timely recognition of ETT placement
and minimize traditional unmeasured radiation exposure.