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Indian Pediatr 2019;56: 694-695 |
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Can Small for Gestational Age Status Affect the Weight-based
Formula for Calculation of Insertional Length of Endotracheal
Tube in Neonates?
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Viraraghavan Vadakkencherry Ramaswamy 1
and Anchala Singh2
From 1Department of Neonatology, Nori
Multispeciality Hospital, Vijayawada, Andhra Pradesh; and
2Department of Pediatrics, AIIMS, Gorakhpur, Uttar Pradesh;
India
Email:
[email protected]
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The normative data for placement of endotracheal tube published recently
in Indian Pediatrics [1] paves the way for a less invasive alternative
of diagnosing a very commonly encountered issue of endotracheal tube
(ET) malposition, that too in a time bound manner. However, we have the
following queries:
1. The anatomical measurements of larynx and trachea
based on gestational age of a neonate are considered to be more accurate
than the weight-based measurements as the later can be influenced by
intrauterine growth retardation [2] e.g., a 28 weeks, 700 grams
small for gestational age (SGA) neonate will have a lengthier larynx and
trachea compared to a 26 weeks appropriate for gestational age (AGA)
neonate of the same weight. This issue is of more significance in
countries where the incidence of SGA is high [3]. Approximately, 20% of
the neonates in this study [1] were SGA. We would like to know if these
SGA neonates were excluded while calculating the weight-based formula
for ET tube insertion depth?
2. The authors have calculated the sample size based
on a pilot study including only two groups of neonates based on weight
alone (<1500 g and >1500 g). However, in the final results, they have
provided nomograms for multiple subgroups based on weight as well as
gestational age. We would like to point out that based on the calculated
mean and SD of some of these subgroups, the required sample size falls
short in some of them.
3. While deriving the regression equation for
insertion length from the various anthropometric parameters, mean age of
enrolment at baseline, which might determine some of the factors
affecting the head circumference such as caput succedaneum,
cephalhematoma and subgaleal bleed, was not mentioned [4]. Moreover,
amongst the enrolled neonates, almost 75% are males. As female neonates
are constitutionally smaller compared to their male counterparts, can
these nomograms be extrapolated to female neonates?
References
1. Singh P, Thakur A, Garg P, Aggarwal N, Kler N.
Normative data of optimally placed endotracheal tube by point-of-care
ultrasound in neonates. Indian Pediatr. 2019;56:374-82.
2. Kempley ST, Moreiras JW, Petrone FL. Endotracheal
tube length for neonatal intubation. Resuscitation. 2008;77:369-73.
3. Lee ACC, Katz J, Blencowe J, Cousens S, Kozuki N,
Vogel JP, Adair L, et al. Born too small: National and regional
estimates of term and preterm small-for-gestational –age in 138
low-middle income countries in 2010. Lancet Global Health.
2013;1:e26-36.
4. Klarić AS, Rajić MT, Crnković HT. Timing of head
circumference measurement in newborns. Clin Pediatr (Phila).
2014;53:456-9.
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