Effect of Low Tidal Volume Ventilation on Postoperative Delirium

Introduction and Objectives: This protocol aims to evaluate the effect of low tidal volume (LTV) ventilation during cardiopulmonary bypass (CPB) on postoperative delirium. Postoperative delirium, commonly seen after cardiac surgeries, negatively impacts patient recovery. It is hypothesized that LTV reduces the risk of delirium by improving cerebral perfusion and oxygenation. The study objectives include comparing the incidence of delirium, ICU stay duration, and 30-day mortality/morbidity rates between groups. Study Design and Methods: This prospective, randomized, controlled trial will involve two groups: patients receiving LTV ventilation and those undergoing apnea during CPB. Inclusion criteria target CABG patients over 18 years of age, while exclusion criteria include emergent surgeries and cognitive impairments. Randomization will ensure balanced group allocation through computer-based methods. Mechanical ventilation parameters will follow standard protocols for both groups. Measurements and Hypotheses: The primary outcome is delirium, assessed using the 3D-CAM method, while secondary outcomes include ICU stay duration and 30-day composite mortality/morbidity rates. LTV ventilation is expected to reduce delirium incidence, shorten ICU stay, and lower mortality/morbidity rates. Statistical analyses will include multivariable models to account for potential confounding factors. Substudies and Limitations: The protocol includes two substudies to evaluate microcirculation and renal perfusion. Limitations may arise from the overlap of sedation effects with delirium symptoms, variations in surgical techniques, and potential data loss during patient follow-ups. Interim analyses are planned to assess the study's safety and effectiveness. The study will be conducted without external funding, adhering to routine clinical practices.