Reliability of ultrasonic diaphragm thickness measurement in mechanically ventilated infants and children: A pilot study

Background. Diaphragmatic atrophy in mechanically ventilated infants and children may be due to ventilator-induced diaphragmatic dysfunction, which could lead to extubation failure. Ultrasound may be used as a means by which diaphragmatic atrophy can be reliably identified. There are currently no data reporting on the use of ultrasound to monitor diaphragm atrophy in the paediatric population.  Objectives. To assess the inter- and intra-rater reliability of using ultrasound to measure diaphragm thickness in mechanically ventilated infants and children.  Method. Diaphragm thickness measurements were compared between two individual researchers for inter-rater reliability and between multiple measurements from a single researcher for intra-rater reliability. Measurements were compared using Intraclass correlation coefficients and Bland- Altman plots.  Results. Results indicated excellent reliability between measurements for both inter-and intra-rater reliability, with slightly better reliability for intra-rater compared with inter-rater reliability. Intraclass correlation coefficients for inter-rater reliability were between 0.77 and 0.98, and 0.94 for intra-rater reliability.  Conclusion. Ultrasound measurements of diaphragm thickness can be used to reliably measure diaphragm thickness in mechanically ventilated infants and children. This modality could therefore be used as a reliable outcome measure for future clinical research studies to establish the relationship between ventilator-induced diaphragmatic atrophy and children who are at risk for extubation failure.