Propofol sedation reduces diaphragm activity in spontaneously breathing patients: ultrasound assessment.

BACKGROUND: The diaphragm is the most important respiratory muscle in humans, and the close relationship between inspired volume and diaphragmatic movement in normal subjects has led to investigations into diaphragmatic activity using ultrasound, during spontaneous breathing and sedative drug infusion. METHODS: A total of 36 consecutive patients undergoing diagnostic procedures under deep propofol sedation were studied. Ultrasound measurements included the following: diaphragmatic thickening end-inspiration (TEI) and endexpiration (TEE). Diaphragmatic thickening fraction (DTF) was calculated from [(TEI TEE) / TEE] at various time points (at T0 basal; at T1 during propofol infusion; at T2 aw…