Reduction of the PaO2/FiO2 Ratio in Acute Aortic Dissection: Relationship Between the Extent of Dissection and Inflammation

Background: Acute aortic dissection (AAD) often accompanies acute respiratory failure. The aim of this study was to clarify the relationship between the incidence of oxygenation impairment and the extent of distal type AAD. Methods and Results: A total of 49 patients with medically treated distal type AAD were retrospectively examined. AAD% was defined as the percentage of the volume of false lumen to that of aorta in the descending aorta. AAD% was measured by computed tomography. C-reactive protein (CRP) levels, white blood cell (WBC) counts, body temperature and arterial partial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio were measured serially. Oxygenation impairment was defined as a PaO2/FiO2 ratio ≤200. This occurred in 19 patients (39%). In patients with oxygenation impairment, AAD% (50.8±10.9% vs 28.0±11.9%, P