After cardiothoracic surgery, it might be difficult to make a clinical diagnosis of ICU-acquired pneumonia. Failing to meet the Johanson criteria (a chest x-ray infiltrate, purulent tracheal secretions, fever, and leukocytosis) accounts for 50% of all cases. Improved diagnosis may occur with a high Clinical Pulmonary Infection Score (CPIS) and a Sequential Organ Failure Assessment (SOFA) score (SOFA↑ ≥ 2). Study participants had recently undergone cardiothoracic surgery, and researchers wanted to see if CPIS or SOFA ↑ more than or equal to  2 may help them avoid developing pneumonia in the intensive care unit. A prospective observational study was conducted. Clinical and laboratory characteristics were used in a derivation cohort to create a Spiegelhalter-Knill-Jones scoring system, which may or may not include the CPIS or SOFA ↑ more than or equal to 2. ICU-acquired pneumonia could only be proven with a positive quantitative lung sample culture. For each of the 2 rating scales, the Area under the receiver operating characteristic curve AUROC was determined. A validation cohort was used to assess the best system. There were a total of 410 cases of suspected ICU-acquired pneumonia in the derivation cohort and 216 in the validation cohort. For CPIS, the AUROC was 0.53 ± 0.03 (P=.29), whereas for SOFA ↑ , more than or equal to 2 it was 0.54 ±0.03. When SOFA ↑ more than or equal to 2 (SOFA model) was supplemented with purulent tracheal secretions and leukocytosis, AUROC jumped to 0.65±0.03 (P<.001). Catecholamine consumption was included in the CPIS (CPIS model), and the AUROC was raised to 0.57±0.03. Even when the SOFA model projected high or low odds, they were accurate. Prediction of ICU-acquired pneumonia in patients undergoing cardiothoracic surgery was marginally enhanced by a clinical scoring system comprising at least SOFA ↑ more than or equal to 2.