SYSTOLIC PRESSURE VARIATION PREDICTS THE RESPONSE TO ACUTE BLOOD-LOSS

Study Objective: To evaluate systolic pressure variation (SPV), define d as the difference between tile maximum and minimum systolic blood pr essure measured during a controlled mechanical respiratory cycle as a predictor of the cardiac output (CO) response to an acute decrease in ventricular preload. Design: Prospective study with each subject servi ng as his or her own control.Setting: Cardiac surgery operating rooms of a university medical center Patients: 15 adults with good ventricul ar function undergoing coronary artery bypass grafting Intervention: D uring stable anesthetic conditions and before surgical stimulation, 50 0 ml of blood was removed from each patient over 10 minutes. Measureme nts and Main Results: CO, central venous pressure (CNP), pulmonary art ery diastolic pressure, and pulmonary artery occlusion pressure (PAOP) and SPV before and after phlebotomy were recorded. Phlebotomy was ass ociated with significant decreases in CVP, PAOP, and CO, and an increa se in SPV. Of these variables, SPV runs the best predictor of the perc ent decrease in CO resulting from blood loss. Conclusion: SPV is a dyn amic measurement, which, by revealing the response to small cyclical c hanges in left ventricular preload that occur during the controlled me chanical respiratory cycle, is a better Predictor than central filling pressures of tile response of CO to acute decreases in preload that o ccur as a result of acute blood loss. (C) 1998 by Elsevier Science Inc .