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.