CRP and respiratory failure: In addition, patients with respiratory failure had significantly higher median levels of C-reactive protein (40.6 vs. 10.0 mg/l, P < 0.0001), median fibrinogen levels (4.3 vs. 3.4 g/l, P < 0.0001) and median D-dimer levels (0.3 vs. 0.2 mg/l, P = 0.0004) (Table 2).