Evaluation of the value of the systolic pressure variations (SPV) under mechanical ventilation and of its components (delta down and delta up) in predicting fluid responsiveness in patients after coronary surgery by comparison with classic parameters. A prospective,randomized study, on 50 patients who underwent CABG surgery, in the early postoperative period (the first two hours). We assessed the following parameters: CO, CI, CVP, PCWP, SAP, DAP, MAP, SVP, delta down and delta up. The including criteria were: sinus rhythm, CI < or = 2,5 l/min/m2, PCP < 18 mmHg. All the patients underwent a fluid challenge (500 ml of colloids in 10 min). Three patients were excluded: 3 for a PCWP > 18 mm Hg, 1 for loosing the sinus rhythm and 1 for an early return in the OR for bleeding. After a new assessment of the same parameters the patients were divided in two groups: group A (28 pts) with a raise of CI > 15%, and group B (22 pts) with a CI variation < 15%. In each group was statistically analyzed the variation of each parameter. Results Both parameters provided by SPV analysis are able to predict the fluid responsiveness with a great accuracy: the positive predictive value of a SPV > 12 mmHg is above 92,85% and of a delta down > 5 mm Hg is above 96,42%; the negative predictive value of a SPV < or = 12 mmHg is above 90,90% and of a delta down = 5 mm Hg is above 95,45%. None of the "classic" pressure parameters (MAP, CVP, PCWP) used in hemodynamic assessment have revealed a statistical significant variation. The SVP method's parameters are superior to classic pressure parameters (MAP, CVP, PCWP) in predicting fluid responsiveness in patients after coronary surgery.