In our patients admitted to the ICU with COPD and Type 2 respiratory failure, the presence of pleural effusion, which was detected radiologically, at admission was found to be significantly associated with increased proBNP levels, increased CTR, and longer ICU length of stay (p = 0.045, p = 0.038, and p = 0.008, respectively) (Table 3). The gene discussed is NPPB; the disease is Pleural effusion.