Fig. 1

Carnitine and acetylcarnitine levels for controls, Class 1, and Class 2 ARDS groups. Relative amounts (peak area ratio of analyte/internal standard) of metabolites shown were determined using stable isotope dilution liquid chromatography high resolution mass spectrometry (LC-HRMS). Controls are shown as black circles (n = 50), Class 1 as blue squares (n = 50), and Class 2 (n = 50) as red triangles with black bars representing medians. Relative carnitine levels are shown in (a) and (b) relative acetylcarnitine levels. c Acetylcarnitine/carnitine ratios are presented for airway controls, Class 1, and Class 2 groups. Group comparisons were performed using the Kruskal–Wallis test. Asterisks indicate P < 0.05 (*), P < 0.01 (**), P < 0.001 (***),  and ns (not significant)