Fig. 2

C-reactive protein levels and gas exchange impairment severity. C-reactive protein levels were not associated with gas exchange impairment severity during standard oxygen therapy (grey boxes, P = 0.088 by Anova). Patients showing a persistently severe gas exchange impairment despite helmet CPAP treatment (i.e., non-responders), showed higher levels of C-reactive proteins (white boxes, P = 0.009 by Anova). Boxes represent median and 25–75 percentiles; filled circles represent 5^th and 95^th percentiles