CRP and chronic obstructive pulmonary disease: P/F ratio: PaO2 (arterial oxygen tension)/FiO2 (fraction of inspired oxygen), COPD: chronic obstructive lung disease, CKD: chronic kidney disease, CRP: C-reactive protein, WBC: white blood cell, SOFA: Sequential (Sepsis-related) organ failure assessment, IVC: inferior vena cava, CT: computed tomography; AP/T: anteroposterior-to-transverse