Fig. 5

Relationship between diaphragm neuromuscular coupling and markers of diaphragm structure and function. Diaphragm neuromuscular coupling is measured as the ratio of transdiaphragmatic pressure to diaphragm electrical activity, Pdi/Edi). Panel A: both decreases and increases in diaphragm thickness relative to baseline diaphragm thickness were associated with lower neuromuscular coupling (p = 0.03, conditional R² = 0.54). Panel B: on the final study day, diaphragm neuromuscular coupling was correlated with diaphragm thickening fraction (an ultrasound measure of diaphragm contractility) (p = 0.013, R² = 0.15). Panel C: diaphragm neuromuscular coupling was correlated with the rapid shallow breathing index (RSBI) measured during a spontaneous breathing trial (p = 0.012, R² = 0.11)