Comparison of different types of ultrasound probes for lung ultrasound in neonates—A prospective randomized comparison study

by Lukas Aichhorn, Lisa Habrina, Tobias Werther, Angelika Berger, Erik Küng

To determine the effect of different types of probes for lung ultrasound in neonates.

Prospective, blinded, randomized, comparative study between 2020 and 2022.

Single-center study at a third level neonatal unit.

Hemodynamically stable infants with either nasal continuous positive airway pressure, high flow nasal cannula or without respiratory support.

Lung ultrasound using either an echo or microconvex probe. As control, the linear probe was used.

Primary outcome measure was neonatologist performed lung ultrasound (NPLUS) score. Secondary outcome measures were number of B-Lines, thickness of the pleural line and subjective image quality. Furthermore, correlation between NPLUS results and clinical data was assessed.

A total of 1584 video loops from 66 patients, with a mean corrected gestational age of 33.8 weeks (SD 4.23) and weight of 1950g (SD 910), respectively, were analyzed. NPLUS score was estimated lower with the echo- and microconvex probe compared to the linear probe, with a coefficient of -2.95 (p < 0.001) and -1.09 (p = 0.19), respectively. Correlation between the pulse oximetric saturation/fraction of inspired oxygen ratio and NPLUS score was moderately strong and best using the microconvex probe (Spearman’s rho = -0.63, p<0.001).

Our results not only confirm the current recommendations, but also demonstrate the extent of the varying results when different probes are used. The differences we discovered call for caution in interpreting scores, especially in the context of guiding therapies and communicating prognoses. Finally, the correlation between NPLUS score and clinical parameters contributes to validating the use of this diagnostic tool.