LTV (Low Tidal Volüme) Ventilation and Diaphragmatic Motion in CABG (Coronary Artery Bypass Grafting)

oronary artery bypass grafting (CABG) surgery performed under cardiopulmonary bypass (CPB) is a complex procedure frequently associated with postoperative pulmonary complications (PPCs). During CPB, mechanical ventilation is usually paused (apnea), which leads to temporary diaphragmatic inactivity. The diaphragm, being a rhythmically contracting muscle under normal physiological conditions, may experience transient dysfunction or even paralysis due to this intraoperative inactivity. Several mechanisms, including loss of neuromechanical coupling, disrupted neuromuscular signaling, altered venous return, and impaired diaphragmatic oxygenation and metabolism, are thought to contribute to this process. Reduced diaphragmatic motion can create a favorable condition for atelectasis, impair oxygenation, and increase the risk of infection in the postoperative period. The resulting transient diaphragmatic dysfunction is considered a potential contributor to the development of PPCs such as pneumonia, pleural effusion, and prolonged mechanical ventilation. Recent research has focused on the protective effects of low tidal volume (LTV) ventilation in surgical and critical care settings. However, limited studies have evaluated its direct impact on diaphragmatic function during CPB, particularly in the context of CABG surgery. There is a need to investigate whether intraoperative application of LTV ventilation during CPB can help preserve diaphragmatic excursion (DE) and reduce PPCs.