Diaphragm Ultrasonography to Predict Noninvasive Respiratory Treatment Failure in Infants With Severe Bronchiolitis

Background: Noninvasive respiratory support is commonly used in treatment of bronchiolitis. Determinants of failure are needed to prevent delayed intubation.

Methods: We conducted a prospective observational pilot study in infants admitted to a pediatric ICU. Diaphragmatic excursion (dExc), diaphragmatic inspiratory/expiratory time, and diaphragmatic thickening fraction (dTF) were recorded at admission, 24 h, and 48 h in both hemidiaphragms.

Results: Twenty-six subjects were included (14 on HFNC and 12 on NIV) with a total of 56 ultrasonographic evaluations. Three subjects required invasive ventilation. Sixty-four percent of the subjects on HFNC required NIV as rescue therapy and 2/14 invasive ventilation (14.2%). In the HFNC group there were no differences in dExc between those who required escalation to NIV or invasive ventilation and those who didn't. Left dTF was higher in subjects on HFNC requiring invasive ventilation versus those needing NIV (left dTF 47% vs 22% [13-30]; P = .046, r = 0.7). Diaphragmatic I:E ratios were higher in infants on HFNC requiring invasive ventilation and diaphragmatic expiratory time was shorter (left P = .038; right P = .02). In the NIV group there were no differences in dExc, I:E ratios, or dTF between subjects needing escalation to invasive ventilation and those who didn't. We found no correlation between a clinical work of breathing score and echographic dTF.

Conclusions: In infants with moderate or severe bronchiolitis receiving HFNC, the use of ultrasonographic left dTF could help predict respiratory treatment failure and need for invasive ventilation. The use of ultrasonographic dExc is of little help to predict both.