Comparative Analysis of the Microcirculation During Cardiac Surgery With Minimal Invasive Versus Conventional Extracorporeal Circulation

Background: Cardiac surgery is performed with the use of extracorporeal circulation which triggers a systemic inflammatory response leading to end-organ dysfunction. Contemporary minimal invasive extracorporeal circulation represents an evolution of the conventional extracorporeal circulation that reduces systemic inflammatory response and improves clinical outcome in large studies. A potential explanation includes preservation of tissue microcirculation with minimal invasive extracorporeal circulation as the underlying pathophysiologic mechanism. Aim: The aim of the present study is to detect differences in tissue microcirculation during cardiopulmonary bypass with minimal (study group) versus conventional (control group) in patients undergoing open heart surgery. Study type: This is a randomized comparative study. Patients: The study group consists of sixty patients scheduled for elective open-heart surgery (coronary artery bypass grafting, aortic valve replacement of combined procedure) at the Cardiothoracic Department School of Medicine Aristotle University of Thessaloniki. Intervention: Patients included in the study will be randomly assigned in two groups with a computer-generated algorithm. Study group will undergo cardiac surgery with minimal invasive extracorporeal circulation while control group will be operated with the use of conventional extracorporeal circulation. Protocol: In both groups tissue microcirculation will be assessed with the use of a specifically designed second generation hand-held video monitoring device which uses sidestream dark field (SDF) imaging placed at the sublingual mucosa. Microcirculatory assessments will be performed at the following time-points: before induction of anesthesia (baseline - T0), after induction of general anesthesia (T1), after initiation of cardiopulmonary bypass (T2) and immediately after weaning cardiopulmonary bypass (T3). Outcomes: The composite primary outcome of the study consists of obtained differences in the main microcirculatory quantitative variables (Proportion of Perfused Vessels, Microvascular Flow Index, Total Vascular Density, Perfused Vessel Density) during defined time points. Secondary outcomes consist of differences in postoperative 30-days morbidity and mortality.