INTRODUCTION
Pneumonia is known as one of the most common serious infections in the
pediatric population worldwide. Pneumonia-related mortality is rare in
developed countries, but in developing countries, it is still one of the
major causes of mortality in childhood ¹,². Most
children can be treated as outpatients, although hospitalization rates
may vary from 19% to 69% in emergency departments
³,⁴. Although the diagnosis is based on clinical
parameters, there are no highly specific criteria for diagnosis. Chest
X-ray (CXR) is not routinely recommended, while the World Health
Organization recommends CXR in children who are clinically diagnosed
with severe pneumonia at tertiary centers. The level is 90% for
children with suspected pneumonia ⁵,⁶. The severity of
the disease can be predicted using demographic characteristics, risk
factors, and clinical parameters, but this may be difficult in an
emergency department. Scoring systems have been adopted to quantify the
severity of the disease and prognosis, but they were based on clinical
findings that can vary according to the subjective assessment of the
clinician ⁷. Biomarkers have been found to be useful in diagnosis, in
differentiating bacterial or viral etiology, and in predicting severity
or prognosis recently, but they are expensive when evaluated in
combination to reflect various pathophysiological pathways
⁸,⁹. Therefore, it is crucial to develop an objective
and useful parameter to demonstrate the severity of the disease and
outcomes.
Point-of-care lung ultrasound (LUS) has increasingly been used in
pediatric emergency settings recently. It is easy to perform, rapid,
cost-effective, repeatable without limitations, and radiation-free. In a
meta-analysis, LUS was found to be more sensitive and specific compared
to CXR for diagnosing pneumonia in children ¹⁰. Another meta-analysis
demonstrated that LUS had sensitivity of 96%, specificity of 93%,
positive likelihood of 15.3, and negative likelihood of 0.06 when
compared to CXR alone or in combination with clinical and laboratory
findings and CXR ¹¹. Jones et al. also showed that the use of LUS
reduced CXR levels over 38% and shortened the length of stay in the
emergency department ¹². Lung ultrasound seems to be a highly promising
tool for pneumonia diagnosis in pediatric emergency departments.
The diaphragm is the main respiratory muscle and diaphragmatic
dysfunction may cause severe problems for respiration ¹³. Diaphragm
ultrasound has been used to evaluate diaphragmatic fatigue after cardiac
surgery or to predict extubation success from mechanic ventilators in
adult and pediatric intensive care units recently
¹⁴–¹⁶. However, there is no study providing
information on the evaluation of DUS in children with the diagnosis of
pneumonia. We hypothesized that DUS parameters could be a new useful
tool to objectively score the severity of the disease and predict
outcomes in previously healthy children with pneumonia in the emergency
department.