Vasoplegic Syndrome

Vasoplegic syndrome is a severe case of vasodilatory shock. It is characterized by severe and persistent hypotension, tachycardia, and normal or increased cardiac output, decrease in systemic vascular resistance, low filling pressure and poor or no response to fluid resuscitation. It is associated with cardiopulmonary bypass, severe sepsis, anaphylaxis, and hemodialysis.It is also described in patients with chronic liver disease. Vasoplegic syndrome is attributed to combination of endothelial injury, arginine vasopressin system dysfunction and release of nitric oxide and other vasodilatory inflammatory mediators e.g. TNF and interferon gamma IF-gamma. The rational for use of vasopressin in the management of vasoplegic syndrome cases not responding to other vasopressors is the low level of vasopressin in these patients. The activation of atrial stretch receptors, higher atrial natriuretic peptide and autonomic dysfunction leads to inhibition of atrial vasopressin release as seen in patients with heart failure. While methylene blue (another drug used for its management) seems to counteract the effect of nitric oxide (NO) and other vasodilators on vascular endothelium and act competitively with NO.