Impact of Ventilator-Associated Pneumonia on Clinical Outcomes in Cardiac Surgical ICU Patients: A Retrospective Cohort Study Using the MIMIC-IV Database

Background Ventilator-associated pneumonia (VAP) is a common postoperative nosocomial infection in patients undergoing cardiac surgery. This study aims to provide a theoretical basis for VAP prevention by analyzing its impact on patient prognosis and identifying risk factors. Materials Data were extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Eligible patients undergoing invasive mechanical ventilation in the cardiac surgical intensive care unit (CVICU) were screened, and their basic information, laboratory data, vital signs, ventilator parameters, and disease information were collected. Statistical methods were employed for data analysis. Results The study included 5975 patients undergoing invasive mechanical ventilation, with 5814 patients without VAP and 161 patients with VAP. After propensity score matching (PSM), there was no significant difference in in-hospital mortality between the VAP and no-VAP groups. However, the VAP group had longer ICU and hospital stays. Patients diagnosed with aortic aneurysm dissection and those with a higher Charlson Comorbidity Index were at greater risk of developing VAP. Higher positive end-expiratory pressure (PEEP), higher minute volume, and lower fraction of inspired oxygen (FiO₂) were associated with an increased risk of VAP. Conclusions VAP prolongs ICU and hospital stays but does not independently increase in-hospital mortality. Key modifiable risk factors include higher PEEP, minute volume, and lower FiO₂.