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.