Figure 4. (A) CRP apheresis (light red column) and course of Horovitz quotient [16]. Horovitz quotient changed from severe (PaO2/FIO2 ≤100 mmHg) to moderate (PaO2/FIO2 ≤200 mmHg) after intubation and ventral positioning, then worsened during CRP apheresis due to dorsal positioning. After CRP apheresis, however, Horovitz quotient, independent from dorsal or ventral positioning, significantly improved until extubation and hospital discharge. (B) CRP apheresis (light red column) and course of lactate (reference range 0.5–1.6 mmol/L). Lactate remained normal during the hospital stay.