ICU Admission-Related Factors Affecting the Duration of Mechanical Ventilation After Elective Cardiac Surgery-Retrospective Cohort Study from a Tertiary Center in Croatia.

Background and Objectives: Enhancing recovery after cardiac surgery involves minimally invasive procedures, early extubation/mobilization, and swift discharge. While mechanical ventilation is often essential post-operation, prolonged invasive ventilation (IMV) increases mortality risk. Duration is influenced by patient factors (age and comorbidities), surgical complexity, and complications. Prognostic scores like EuroSCORE II, sequential organ failure assessment (SOFA), the Charlson Comorbidity Index (CCI), and the vasoactive-inotropic score (VIS) help to predict ventilation needs. The aim of this study is to analyze the effect of pre-/post-operation factors and procedure type as predictors of ventilation time. Materials and Methods: This is a retrospective cohort observational study analyzing factors affecting the duration of postoperative mechanical ventilation in elective cardiac surgical patients treated between 1 January and 31 December 2024 in a tertiary center in continental Croatia. Patients were stratified into two groups according to the duration of IMV: normal (first three quartiles) and prolonged (upper quartile). In total, 493 elective cardiac surgical patients operated on under general endotracheal anesthesia with sternotomy or mini-sternotomy were admitted postoperatively to the cardiovascular ICU and mechanically ventilated during the observed period, and 463 patients were included in the final analysis after the exclusion criteria had been applied. Results: The mean age was 64.7 ± 9.8 years, and 28.7% of the cohort were females while 71.3% were males. The median Charlton Comorbidity Index was 4 (IQR 3-5), the VIS was 2 (IQR 0-3), the SOFA score at ICU admission was 5 (IQR 3-6), and the adjusted SOFA score was 3 (IQR 2-4). In the multivariate logistic regression model, a significant effect of female sex (OR 1.98), age (OR 1.05), VIS (OR 1.05), and history of previous cardiac surgery (OR 6.67) on the duration of mechanical ventilation was observed. In the time-to-extubation multivariate analysis, there was a significant effect of re-do surgery (HR 3.70), corrected SOFA score (HR 1.14), and VIS (HR 1.05) on the duration of mechanical ventilation. There was no significant effect of the type of surgery (CABG, aorta, aortic valve, mitral/tricuspid valve, or other) or the amount of chest tube drainage on the duration of mechanical ventilation. Conclusions: A history of previous cardiac surgery and the vasoactive-inotropic score during the first 24 postoperative hours in the ICU are the strongest predictors of the duration of mechanical ventilation after elective cardiac surgery, with a statistically significant effect present in both the logistic regression model and hazard ratio analysis. Further analyses with more variables are warranted in the future to refine the prognostic model.