Objective To explore the feasibility of measuring the mobility and contraction velocity of bilateral diaphragm by anatomical M-mode ultrasound

and to provide basis for the diagnosis of diaphragm motor dysfunction.Methods A total of 118 healthy adults were selected

the movement and inspiratory time of bilateral diaphragm were measured twice during quiet breathing with anatomical M-mode ultrasound by the same examiner

and the contraction velocity of diaphragm was calculated.The normal reference range of diaphragm movement parameters were determined by the corresponding values of the 10th and 90th percentiles. Intraclass correlation coefficient（ICC） was used to evaluate the repeatability of ultrasound parameters

and the relationship between diaphragm movement and sex

age

smoking history

body mass index（BMI） was analyzed.Results The normal reference range of diaphragm movement parameters:diaphragm mobility was 9～23 mm

inspiratory time was 972～1482 ms

contraction velocity was 0.82～1.87 cm/s

there were no significant difference in bilateral diaphragm movement parameters.The ICC of diaphragm mobility and inspiratory time measured by anatomical M-mode ultrasound were more than 0.9. There was no significant correlation among diaphragm movement and sex

age

smoking history and BMI.Conclusion Anatomical M-mode ultrasound can accurately measure the mobility of bilateral diaphragm

and has good repeatability.It can be widely used in clinic for monitoring diaphragm movement.