To analyze the relationship between blood lactate (Lac), early lactate clearance (LCR), B-type natriuretic peptide (BNP), D-dimer (D-D) and prognosis in elderly patients with chronic obstructive pulmonary disease (COPD) complicated with respiratory failure.

The clinical data of 80 elderly patients with COPD complicated with respiratory failure admitted to the Department of Respiratory and Critical Care Medicine in Shuyang Hospital from April 2022 to February 2025 were retrospectively analyzed, and they were divided into the death group with 11 cases and the survival group with 69 cases according to the follow-up outcomes within 28 days after admission. 76 patients with COPD but without respiratory failure were set as the control group. The levels of Lac, LCR, BNP and D-D in the elderly COPD complicated with respiratory failure group and the control group, as well as different disease degrees and prognoses of elderly COPD complicated with respiratory failure were compared, the correlations between Lac, LCR, BNP, D-D levels and arterial partial pressure of oxygen (PaO₂) and arterial partial pressure of carbon dioxide (PaCO₂) in elderly patients with COPD and respiratory failure were analyzed, and the receiver operating characteristic (ROC) curve was used to analyze the prognostic value of indicators in elderly patients with COPD combined with respiratory failure.

The levels of Lac, BNP and D-D in COPD group with respiratory failure were higher than those in control group, but LCR was lower than those in control group (P<0.05).The levels of Lac, BNP and D-D levels in severe respiratory failure group were higher than those in mild-moderate respiratory failure group, and LCR was lower than those in mild-moderate respiratory failure group (P<0.05). The levels of Lac, BNP and D-D in COPD patients with respiratory failure were higher than those in survival group, and the LCR was lower than those in survival group (P<0.05). The levels of Lac, BNP and D-D were positively correlated with PaCO₂ in elderly patients with COPD combined with respiratory failure (P<0.05), the levels of Lac, BNP and D-D were negatively correlated with PaO₂ (P<0.05), the levels of LCR were negatively correlated with PaCO₂ in elderly patients with COPD combined with respiratory failure (P<0.05), and the levels of Lac, BNP and D-D were positively correlated with PaO₂ (P<0.05). ROC curve analysis showed that the AUC of the combined detection was greater than that of Lac, LCR, BNP, and D-D individually.

Lac, LCR, BNP and D-D levels in elderly patients with COPD complicated with respiratory failure have certain correlation with the severity of the disease and prognosis, and can be used for prognosis assessment.