Ultrasound assessment of diaphragm thickness, contractility, and strain in healthy pediatric patients

Abstract

AbstractBackgroundUltrasound‐based diaphragmatic assessments are becoming more common in pediatric acute care, but baseline pediatric diaphragm thickness and contractility values remain unknown.MethodsWe conducted a prospective, observational study of healthy children aged <18 years undergoing elective surgery. Diaphragm thickness at end‐expiration (Tdi‐exp), thickening fraction (DTF) and excursion were measured by ultrasound during spontaneous breathing and during mechanical ventilation. Diaphragm strain and peak strain rate were ascertained post hoc. Measurements were compared across a priori specified age groups (<1 year, 1 to <3, 3 to <6, 6 to <12, and 12 to <18 years) and with versus without mechanical ventilation.ResultsFifty subjects were evaluated (n = 10 per age group). Baseline mean Tdi‐exp was 0.19 ± 0.04 cm, DTF 0.19 ± 0.09, excursion 1.69 ± 0.97 cm, strain −10.3 ± 4.9, peak strain rate −0.48 ± 0.21 s−1. No significant difference in Tdi‐exp or DTF was observed across age groups (p > .05). Diaphragm excursion increased with age (p < .0001). Diaphragm strain was significantly greater in the 12–17‐year age group (−14.3 ± 6.4), p = .048, but there were no age‐related differences in peak strain rate (p = .08). During mechanical ventilation, there were significant decreases in DTF 0.12 ± 0.04 (p < .0001), excursion 1.08 ± 0.31 cm (p < .0001), strain −4.60 ± 1.93 (p < .0001), and peak strain rate −0.20 ± 0.10 s−1 (p < .0001) while there was no change in Tdi‐exp 0.18 ± 0.03 cm (p = .25) when compared to baseline values.ConclusionPediatric Tdi‐exp, DTF, and diaphragm peak strain rate were similar across age groups. Diaphragm excursion and strain varied across age groups. All measures of diaphragm contractility were diminished during mechanical ventilation.