vasoplegic syndrome vasoplegic syndrome vasoplegic syndrome (vps) is a postperfusion syndrome characterized by low systemic vascular resistance and a high cardiac output. causes vps occurs more frequently after on pump cabg surgery versus off pump cabg surgery. hypothermia during surgery may also increase ones risk of developing vps post operatively. diagnosis definition vasoplegic syndrome is defined as low systemic vascular resistance (svr index <1,600 dyn∙sec/cm5/m2) and high cardiac output (cardiac index >2.5 l/min/m2) within the first 4 postoperative hours. treatment gross pathology of a normal brain and a brain of a patient treated with methylene blue before death. there is some evidence to support the use of methylene blue in the treatment of this condition. epidemiology one case series reports a rate of 1 in 120 cases.