Appropriate body position and site for diaphragm ultrasound: Comparison with inspiratory mouth pressure

Objective: This study aimed to examine the appropriate body position and anatomical site for DUS through comparisons with maximal inspiratory pressure (MIP). Methods: Thirty healthy adults were included in the study. MIP was measured using a spirometer. DUS was performed in both the right and left intercostal spaces in both sitting and supine positions. The diaphragm thickness at functional residual volume (TDFRC) and total lung capacity (TDTLC) were measured, and the fractional change in diaphragm thickness (TF) was calculated under each condition. To assess interobserver reproducibility, DUS was performed by an experienced examiner and a novice examiner. Results: Among the DUS parameters, the TDFRC measured at the right intercostal space in the sitting position showed the strongest correlation with MIP (r = 0.68, p