OBJECTIVE To explore the time windows for postoperative pneumonia in patients undergoing different surgeries, providing evidence-based references for optimizing infection monitoring and prevention and control strategies.

METHODS Sociodemographic characteristics, clinical information and surgical details of 263 patients with postoperative pneumonia from four different types of medical institutions between Jan. 2019 and Dec. 2024 were retrospectively collected. The time windows for postoperative pneumonia in patients undergoing different surgeries were analyzed.

RESULTS There were no statistically significant differences in the time windows for postoperative pneumonia among groups in terms of sociodemographic factors and underlying diseases. However, statistically significant differences were observed in the time windows for postoperative pneumonia based on surgery type, incision type, surgical approach and surgery duration (P < 0.05). The average time for the onset of postoperative pneumonia in 263 patients was 2.00 (1.00, 7.00) days. The postoperative time windows varied for surgeries involving different systems. The peak incidence occurred on day 0 (16 cases) and day 1 (17 cases) after neurological surgery, while the peak incidence for digestive system and orthopedic surgeries was on day 1. The time span for the onset of pneumonia after skin surgeries was wider (0-53 days postoperatively) without a clear peak. In addition, 33.33% of cardiovascular system surgery cases developed pneumonia 10 days postoperatively. There were also significant time differences in the diagnostic elements of postoperative pneumonia, with fever and abnormal white blood cell counts appearing earlier (median appearance time length: 4.00 days) than lung imaging changes (median appearance time length: 7.00 days).

CONCLUSIONS This study demonstrates significant time differences in the onset of postoperative pneumonia and confirms the significant spatiotemporal heterogeneity in the diagnostic elements of postoperative pneumonia. These findings provide a quantitative basis for developing dynamic, surgery-type-specific monitoring protocols and prevention and control measures for postoperative pneumonia.