Evaluating the Maximal Diaphragm Thickening Fraction in Healthy Participants

Position the patient in a semi recumbent position on their back. Then using the B-mode ultrasound, identify the diaphragm and optimize the image quality. Next, click the M-mode button to place the ultrasound into M-mode.

While in M-mode, guide the participant to perform a maximum volitional inspiratory effort against a non occluded airway. Freeze the recording and save the image. Next, measure the diaphragm thickness fraction at end expiration and peak inspiration during a maximum inspiratory trial.

Then using the given equation, calculate the diaphragm thickening fraction max for each breath. The max thickening fraction is taken as the highest value from all three trials. The maximal diaphragm thickening fraction in healthy adults ranges from 30 to 130%In critically ill patients, diaphragm thickening fraction max less than 30%predicts a higher risk of failed weaning from mechanical ventilation.