Microcirculatory effects of cardiopulmonary bypass primings in coronary artery bypass graft surgery the prime randomised clinical trial for a physiological proof-of-principle

Objectives Cardiopulmonary bypass (CPB) impairs endothelial function, causing oedema and disturbed microcirculatory perfusion, that contribute to organ dysfunction following cardiac surgery. We hypothesised that the composition of CPB prime fluids with either albumin or gelofusine preserves sublingual microcirculatory perfusion in patients undergoing coronary artery bypass graft surgery. Methods Thirty-four patients were subjected to CPB primed with 1500 ml of either albumin/ringers (n = 8, gelofusine/ringers ( n = 11), or solely ringers plus retrograde autologous priming (RAP) ( n = 15). All solutions included 100 ml of mannitol. The primary outcome was perfused vessel density (PVD) assessed after anaesthesia induction, aortic cross-clamping, weaning from CPB, upon intensive care unit (ICU) arrival and 24 h after ICU arrival. Results CPB immediately impaired PVD across all groups, persisting until ICU arrival. The decrease in PVD was most profound with albumin/ringers (estimated mean difference between baseline and ICU arrival −7.56 [95% CI -11.53 to −3.59] mm . mm -2 ), compared to gelofusine/ringers (−4.10 [−7.53 to −0.67] mm . mm -2 ), and ringers/RAP (−3.77 [-6.64 to −0.90] mm . mm -2 ), without differences between groups ( p = 0.41). In patients receiving gelofusine/ringers COP was preserved after aortic cross clamping. Concentration of inflammatory (interleukin-6) and endothelial damage markers (angiopoietin-2) were increased with albumin/ringers compared with gelofusine/ringers and ringers plus RAP. Conclusion In this exploratory physiological study, all of the three CPB priming strategies, albumin/ringers, gelofusine/ringers or ringers plus RAP, similarly induced perioperative microcirculatory dysfunction in patients undergoing CABG surgery.