INTRODUCTION
Acute bronchiolitis (AB) is a viral inflammation of the lower
respiratory tract in children younger than 24 months, constituting an
important economic and healthcare burden. It is the most common
infection of infants requiring hospital admission. Although it usually
presents with a benign course, progression to severe illness requiring
respiratory support and admission to an intensive care unit
unfortunately occurs rapidly in some cases. For this reason, AB is
associated with notable morbidity and mortality worldwide.
Diagnosis is based on clinical evaluation and the routine use of
laboratory or chest X-ray (CXR) is not recommended because of
unnecessary antibiotic overuse ¹. In order to quantify the severity of
the disease, clinical severity scores were developed and are widely used
to assess the course of the disease and treatment strategy, but they are
all based on the subjective clinical assessment of the physician ².
Point-of-care lung ultrasound (LUS) has been used with growing
enthusiasm in pediatric emergency departments recently. It is practical,
inexpensive, reproducible, and easy to learn and it seems to be the
“visual stethoscope” of the 21st century ³ˉ⁵. Transient tachypnea of
the newborn, respiratory distress syndrome, pneumonia, pulmonary edema,
pneumothorax, and bronchiolitis are some diseases and anomalies that can
be assessed using LUS ⁶ˉ⁸. Subpleural lung consolidations, confluent
B-lines, and pleural line abnormalities were evaluated to be specific
ultrasound signs of AB, and the extent of the lesions detected by LUS
was associated with the severity of the disease (9). Moreover, LUS was
found to be superior to CXR in studies that assessed bronchiolitis
patients ¹⁰ˉ¹². All these advantages quantify LUS as a useful assessment
device, especially for pediatric emergency settings. A bronchiolitis
ultrasound score (BUS) was also developed to predict the severity of
illness ¹⁰. It was found to have agreement with clinical severity
scores, but performing LUS for bilateral anterior and posterior chest
areas and then calculating the score can be difficult and
time-consuming. Meanwhile, the infant may not stay calm through the
whole period of sonographic assessment. For this reason, a rapid,
practical, reliable, and more objective severity score is needed to
evaluate patients in the emergency department.
Noninvasive evaluation of the diaphragm by using ultrasonography has
gained popularity in both adult and pediatric intensive care units
recently. The diaphragm is the main respiratory muscle and diaphragmatic
dysfunction may be underdiagnosed because of nonspecific features such
as weaning failure from mechanical ventilator, unexplained respiratory
distress, lung collapse, or paradoxical abdominal movement during
respiration. In the pediatric population, there are few studies
evaluating diaphragm parameters to predict extubation success from
mechanic ventilation, diaphragmatic fatigue after cardiac surgery, or
normal values of diaphragm parameters in healthy children, and only one
study has addressed this issue in bronchiolitis patients ¹¹ˉ²¹. Thus,
the aim of this study was to evaluate diaphragmatic parameters in
previously healthy bronchiolitis patients and identify correlations
between clinical and ultrasonographic severity scores and outcomes in
order to develop a more objective and useful tool for use in the
emergency department.