Introduction
Asthma represents one of the most common chronic conditions of childhood1-4. It is a leading cause for both pediatric emergency department (PED) visits and hospital admissions amongst children. Despite all of the investigational tools available to physicians, it can sometimes be difficult to clinically discriminate acute asthma from other diagnoses, including pulmonary infection, lobar atelectasis and pneumothorax. Thus, the diagnosis of asthma often relies on clinical features found through acquiring a thorough medical history, and conducting a physical examination5,6. Lung ultrasound (LUS) has emerged as a rapid, bedside method of investigating respiratory distress7. It has proven to be both sensitive and specific in diagnosing common pediatric respiratory pathologies such as pneumonia, pneumothorax, pulmonary effusion and neonatal lung diseases8-13. Lung ultrasound has also been compared to extent of parenchymal changes on CT scans in the pediatric population and to extent of lung disease in different pathologies for which lung ultrasound scoring systems have been developed12,14-18.
Previous studies have looked at LUS in pediatric patients with asthma when presenting to the PED in respiratory distress19,20. A study by our group found that 45% of children presenting with an acute asthma exacerbation had a positive LUS20. The cause of these findings is uncertain. It was hypothesized these findings were related to possible concomitant respiratory infections, since viral upper respiratory tract infection is the most common cause of asthma exacerbation in pediatric patients21. However, a more in-depth understanding of the LUS findings in children with asthma is required for its routine application in the acute PED setting.
The primary objective of this study was to characterize LUS findings in a cohort of pediatric patients with a definitive diagnosis of asthma (confirmed by spirometry or methacholine challenge test (MCT)) who were not experiencing an asthma exacerbation and were at their baseline state of health. The secondary objective was to compare the clinical characteristics of participants with positive LUS to those with negative LUS, in order to identify potential predictors of abnormal LUS findings.