F2 and peritonitis: Univariate analysis of the modeling population showed that procalcitonin, aspartate transaminase, triglyceride, blood urea nitrogen, lactic acid, Pro-BNP, cholinesterase, prothrombin time, D-dimer, phosphorus, albumin, globulin, pulse oxygen saturation, respiratory rate, GCS, lung infection, and peritonitis were associated with respiratory failure (p < 0.001; Table 2).