BackgroundExcessive bleeding, incomplete wound drainage, and subsequent accumulation of blood and clots in the pericardium have been associated with a broad spectrum of bleeding-related complications after cardiac surgery. We developed and studied the continuous postoperative pericardial flushing (CPPF) method to improve wound drainage and reduce blood loss and bleeding-related complications. MethodsWe conducted a single-center, open-label, ITT, randomized controlled trial at the Academic Medical Center Amstserdam. Adults undergoing cardiac surgery for non-emergent valvular or congenital heart disease (CHD) were randomly assigned (1:1) to receive CPPF method or standard care. The primary outcome was actual blood loss after 12-hour stay in the intensive care unit (ICU). Secondary outcomes included bleeding-related complications and clinical outcome after six months follow-up. FindingsBetween May 2013 and February 2016, 170 patients were randomly allocated to CPPF method (study group; n = 80) or to standard care (control group; n = 90). CPPF significantly reduced blood loss after 12-hour stay in the ICU (-41%) when compared to standard care (median differences -155 ml, 95% confidence interval (CI) -310 to 0; p=≤0·001). Cardiac tamponade and reoperation for bleeding did not occur in the study group versus one and three in the control group, respectively. At discharge from hospital, patients in the study group were less likely to have pleural effusion in a surgically opened pleural cavity (22% vs. 36%; p = 0·043). InterpretationOur study results indicate that CPPF is a safe and effective method to improve chest tube patency and reduce blood loss after cardiac surgery. Larger trials are needed to draw final conclusions concerning the effectiveness of CPPF on clinically relevant outcomes.