Expiratory abdominal muscle thickness, a new point of care ultrasound measure for respiratory muscle mass in the intensive care unit: a prospective observational cohort study.

BACKGROUND: Even if expiratory muscles are key muscles in intensive care unit (ICU) patients, the association between their thickness and mortality has never been assessed. This study aimed to determine whether expiratory abdominal muscle thickness assessed by ultrasonography (US) was associated with 28-day mortality in ICU patients.

BASIC PROCEDURES: US expiratory abdominal muscle thickness was measured within the first 12 h after ICU admission. The primary endpoint was 28-day mortality.

MAIN FINDINGS: In 310 analyzed patients, a thinner total abdominal expiratory muscle thickness at admission was associated with 28-day mortality (median value with interquartile range: 10.8 [10; 14.6] versus 16.5 [13.4; 20.7] mm). Total abdominal expiratory muscle thickness had an area under the curve of 0.78 [0.71;0.86] to discriminate 28-day mortality.

CONCLUSIONS: US expiratory abdominal muscle thickness was associated with 28-day mortality, supporting its use in predicting ICU patient outcome.