Ultrasound assessment of ventilator-induced diaphragmatic dysfunction in mechanically ventilated pediatric patients

Abstract

Introduction: Ultrasonography has recently emerged as a promising technique that can rapidly estimate diaphragm function, especially during the weaning period. The aims of this study were to describe the evolution of diaphragmatic morphology and functional measurements by ultrasound in ventilated children.

Material and methods: This was a prospective, observational, single-center study. All the children admitted to our Pediatric Intensive Care Unit requiring mechanical ventilation for more than 48 h were included. Diaphragmatic thickness and the thickening fraction were assessed by ultrasound.

Results: From June to December 2018, 47 patients (median age 3 months; interquartile range, 1-17) underwent 164 ultrasonographic evaluations. The median duration of mechanical ventilation was 168 h (interquartile range, 96-196). At the initial measurement, the thickness at end-inspiration was 2.2 mm (interquartile range, 1.8-2.5) and the thickness at end-expiration was 1.8 mm (interquartile range, 1.5-2.0) with a median decrease in thickness of -14% (interquartile range, -33% to -3%) and a -2% daily atrophy rate (interquartile range, -4.2% to 0%). Diaphragmatic atrophy was observed in 30/47 cases. Children who had been exposed to neuromuscular blockade infusion (n = 31) had a significantly lower mean thickness [-22% (interquartile range, -34% to -13%) vs. -6% (interquartile range, -12% to 0%); p = 0.009] and increased daily atrophy rate [-2.2% (interquartile range, -4.6 to 0%) vs. -1.4% (interquartile range, -2.6 to 0%); p = 0.049] compared to unexposed children. The decrease in thickness was significantly less in children ventilated for at least 12 hours with pressure support before extubation compared with those with shorter periods of spontaneous respiratory effort [-9.5% (interquartile range, -21 to 0%) vs. -26% (interquartile range, -37 to -12%); p = 0.011].

Conclusions: Point-of-care diaphragmatic ultrasound can detect diaphragmatic atrophy in mechanically ventilated children. Diaphragmatic atrophy was strongly associated with the use of mechanical ventilation and neuromuscular blockade. Diaphragmatic thickness also tended to decrease less in the pre-extubation stage with pressure support. We found no correlation between progressive diaphragm thinning, extubation failure, or an increased need for non-invasive ventilation post extubation.

Keywords: Diaphragm atrophy; Ultrasound; Ventilator induced diaphragm dysfunction; Ventilator weaning.