Establishing feasibility and reliability of subcutaneous fat measurements by ultrasound in very preterm infants

Background

Regional fat distribution may be a marker of metabolic health and brain growth in preterm infants. Point of care ultrasound has been used to assess regional fat in term infants but has not been used widely in preterm infants.

Objective

To longitudinally quantify changes in body composition metrics using bedside ultrasound in very preterm infants.

Study design

Very preterm infants (N = 69) were enrolled after birth and body composition assessments were done through 36 completed weeks’ postmenstrual age (PMA). Linear mixed effects regression was used to model change in body composition assessments over time.

Results

There was an average increase across PMA for each body composition outcome. Biceps ultrasound subcutaneous fat (SQF) thickness increased by 0.11 mm (95% CI: 0.09, 0.13) each postmenstrual week. Triceps, subscapular, and abdominal ultrasound SQF remained constant through 28 weeks’ PMA, then increased each week through 36 completed weeks’ PMA. The inter-rater and intra-rater intraclass correlation coefficients for the ultrasound SQF measures ranged from 85.8 to 99.9.

Conclusion

Use of ultrasound as a novel method to assess regional fat distribution in very preterm infants is feasible and reliable.

Impact

Regional fat distribution may be a marker of metabolic health and brain growth in preterm infants. Gold standard body composition assessments may not be feasible in medically fragile very preterm infants.

This study assesses longitudinally changes in regional adiposity development using bedside ultrasound techniques in a multicenter cohort of very preterm infants.

Results of this study show that bedside ultrasound as a novel method to assess regional subcutaneous fat distribution and development in very preterm infants is both feasible and reliable.