DISCUSSION
Recently, point-of-care LUS has been used with growing interest in
emergency settings. In a review, ultrasound was defined as the “visual
stethoscope” of the 21st century ²⁰. Diaphragm
ultrasound is also easy to learn and perform, and the assessments take a
short time. It seems that DUS can be easily carried out while performing
LUS in the emergency department. Diaphragm ultrasound provides
objective, measurable parameters to the clinician, as clinical
evaluation or treatment strategies are mostly performed based on
subjective clinical findings and thus reflect individual variability.
For this reason, in a crowded emergency setting, DUS helps the clinician
obtain more objective, reliable, and measurable data. To our knowledge,
this is the first study evaluating diaphragm parameters with ultrasound
in previously healthy children with pneumonia.
To date, most of the studies about DUS have been performed in adults
¹⁵, ²¹–²⁴. There are few such
studies in children, and in those studies, diaphragmatic dysfunction was
evaluated mostly in intensive care units. Diaphragm parameters were
obtained to predict diaphragmatic fatigue after cardiac surgery or
successful weaning from mechanic ventilation ²⁵–²⁷.
Diaphragm thickness and TF were found to be important predictors of
extubation success from mechanic ventilators; TF of <17% was
associated with weaning failure. In a few studies, normal values of
diaphragm parameters in healthy infants/children were also evaluated
²⁸,²⁹. None of these studies evaluated all of the
parameters that we used to assess diaphragm function. There is one study
about previously healthy infants with bronchiolitis aged 1–12 months,
evaluating ultrasonographic examinations of the diaphragm to predict the
severity of respiratory distress and outcomes ³⁰. To our knowledge, this
is the first study measuring ES with DUS in addition to these
parameters.
El-Halaby et al. ²⁸ evaluated the measurements of diaphragmatic
excursion and thickness in healthy infants and children. They divided
patients into 4 groups according to age and obtained measurements.
Correlating our findings with theirs, both diaphragmatic excursion and
thickness values were lower than those of even the youngest age group,
suggesting that pneumonia causes diaphragmatic dysfunction. Moreover, TF
values were associated with the severity of the pneumonia, indicating
that diaphragm contractility decreases as the disease severity
progresses. Inspiratory slope and ES values were also correlated with
PRESS scores, suggesting that inspiratory and expiratory efforts were
increased in cases of severe pneumonia. Length of stay in the hospital
was correlated with IS and ES as a practical predictor for outcome.
Buonsenso et al. ³⁰ found that severe bronchiolitis patients had lower
TF than in moderate or mild cases, but there was no statistically
significant difference. Thickening fraction was found to have a
correlation with SpO2 at first evaluation in
bronchiolitis patients. Diaphragm excursion was lower in patients with
moderate eco scores than in those with mild or normal scores, but there
was no statistically significant difference between mild and normal eco
scores. They concluded that IS measurements were higher in patients who
required respiratory support for bronchiolitis, consistent with our
study. Additionally, we found that IS and ES values were both associated
with the need for respiratory support, signaling that higher inspiratory
and expiratory efforts would predict worsening outcomes. In our study,
it was shown that there were significant positive correlations between
both IS and ES and respiratory rate, while they had negative
correlations with SpO2 levels evaluated at the time of
admission to the emergency department. Furthermore, TF values were
negatively correlated with respiratory rate. Interestingly, there was no
difference between PRESS groups according to diaphragm excursion
measurements. This discrepancy may be due to the different pathological
features of the two diseases, namely bronchiolitis and pneumonia,
respectively.
Our study has some limitations. First, the number of patients was not
high enough to establish groups according to age and weight and compare
the DUS parameters between them according to severity scores.
Nevertheless, diaphragmatic excursion and thickness measurements were
lower than those of the youngest healthy age group recorded in another
study (30), suggesting that pneumonia does cause diaphragmatic
dysfunction. Second, we did not obtain DUS results after recovery, so
differences in measurements in the healthy and sick periods were not
evaluated.
In conclusion, DUS may be a promising and useful tool to assess
diaphragmatic dysfunction in patients diagnosed with pneumonia.
Diaphragm parameters, especially TF, IS, and ES, may provide objective
and reliable information to predict the severity of the illness, the
need for respiratory support, and outcomes. Nevertheless, studies with
larger case series are required to reveal the benefits of diaphragm
ultrasound in children with different diagnoses.