[Can a simple lung ultrasound score predict length of ventilation for infants with severe acute viral bronchiolitis?]

Background: Lung ultrasound (LU) is a bedside point-of-care technique in critical care and emergency medicine. LU is quick and non-irradiating, and provides accurate diagnostic information when compared with chest radiographs. Specific LU signs have been described for bronchiolitis. This study aimed to evaluate the correlation between severity of LU-diagnosed lung lesions, using a quantitative LU score, and the length of non-invasive ventilation (LOV) for infants diagnosed with severe viral bronchiolitis.

Methods: This was a prospective observational single-center study conducted at a level 3 pediatric intensive care unit. A LU score was calculated for 47 infants under 6 months of age with severe acute viral bronchiolitis during the 2015-2016 epidemic, and the number of intercostal spaces with consolidation or interstitial syndrome was counted for each lung. The LU score is based on the presence of A lines or B-line artifacts and consolidation (0-2 points). The modified Wood score (mWCAS) was used to define clinical severity. Other parameters such as gestational age at birth, age, supplemental oxygen (LOS), and length of stay were recorded. All LU scans were later reviewed by two trained ultrasonographers to assess the score's inter-rater reproducibility.

Results: The LU score on admission (3.5±2.6) did not correlate with LOV (69±68.6), mWCAS score (4±1.6), LOS (3±3.4), or length of stay (4±3.4). However, there was a significant correlation between the number of affected intercostal spaces on the right and LOS (Spearman's Rho 0.318; P=0.037).

Conclusion: This is the first study to evaluate the use of LU in infants needing PICU admission for severe acute bronchiolitis. The LU score does not correlate with LOV, mWCAS, LOS, or length of stay, but the number of pathological intercostal spaces on the right side correlates significantly with LOS. Although LU scores have been validated for the newborn and the adult, this has been in the setting of restrictive lung diseases. Bronchiolitis is a predominantly obstructive lung disease and this may explain the lack of performance observed.