VASOPLEGIA OR VASOPLEGIC SYNDROME (VS) is an ill-defined clinical state often characterized by low systemic blood pressure, low systemic vascular resistance, high or normal cardiac output, and increased requirement for intravenous fluid and vasopressor administration. 1 Friedrich M. Brauer A. Tirilomis T. et al. Methylene blue administration in severe systemic inflammatory response syndrome (SIRS) after thoracic surgery. Ann Thorac Cardiovasc Surg. 2002; 8: 306-310 PubMed Google Scholar , 2 Shanmugam G. Vasoplegic syndrome—The role of methylene blue. Eur J Cardiothorac Surg. 2005; 28: 705-710 Crossref PubMed Scopus (126) Google Scholar It is a form of vasodilatory shock in which a lack of vascular tone leads to the inability to achieve an adequate perfusion pressure. 3 Landry D.W. Oliver J.A. The pathogenesis of vasodilatory shock. N Engl J Med. 2001; 345: 588-595 Crossref PubMed Scopus (867) Google Scholar , 4 Fischer G.W. Levin M.A. Vasoplegia during cardiac surgery: Current concepts and management. Semin Thorac Cardiovasc Surg. 2010; 22: 140-144 Abstract Full Text Full Text PDF PubMed Scopus (163) Google Scholar This clinical scenario is often witnessed in cardiac surgery as a consequence of cardiopulmonary bypass (CPB) triggering a systemic inflammatory response. The incidence of VS after cardiac surgery is quite variable, ranging from 5% to 25% 5 Cremer J. Martin M. Redl H. et al. Systemic inflammatory response syndrome after cardiac operations. Ann Thorac Surg. 1996; 61: 1714-1720 Abstract Full Text PDF PubMed Scopus (469) Google Scholar , 6 Levin M.A. Lin H.M. Castillo J.G. et al. Early on-cardiopulmonary bypass hypotension and other factors associated with vasoplegic syndrome. Circulation. 2009; 120: 1664-1671 Crossref PubMed Scopus (155) Google Scholar , 7 Levin R.L. Degrange M.A. Bruno G.F. et al. Methylene blue reduces mortality and morbidity in vasoplegic patients after cardiac surgery. Ann Thorac Surg. 2004; 77: 496-499 Abstract Full Text Full Text PDF PubMed Scopus (211) Google Scholar , 8 Taylor K.M. SIRS—The systemic inflammatory response syndrome after cardiac operations. Ann Thorac Surg. 1996; 61: 1607-1608 Abstract Full Text PDF PubMed Scopus (112) Google Scholar to as high as 42% in patients undergoing insertion of a left ventricular assist device for end-stage heart failure. 9 Argenziano M. Chen J.M. Choudhri A.F. et al. Management of vasodilatory shock after cardiac surgery: identification of predisposing factors and use of a novel pressor agent. J Thorac Cardiovasc Surg. 1998; 116: 973-980 Abstract Full Text Full Text PDF PubMed Scopus (313) Google Scholar VS has also been described in some patients with septic shock 10 Donati A. Conti G. Loggi S. et al. Does methylene blue administration to septic shock patients affect vascular permeability and blood volume?. Crit Care Med. 2002; 30: 2271-2277 Crossref PubMed Scopus (70) Google Scholar , 11 Kwok E.S. Howes D. Use of methylene blue in sepsis: A systematic review. J Intensive Care Med. 2006; 21: 359-363 Crossref PubMed Scopus (110) Google Scholar , 12 Brown G. Frankl D. Phang T. Continuous infusion of methylene blue for septic shock. Postgrad Med J. 1996; 72: 612-614 Crossref PubMed Scopus (52) Google Scholar and in patients receiving protamine for reversal of heparin after CPB. 13 Kemp S.F. Lockey R.F. Anaphylaxis: A review of causes and mechanisms. J Allergy Clin Immunol. 2002; 110: 341-348 Abstract Full Text Full Text PDF PubMed Scopus (372) Google Scholar , 14 Neugut A.I. Ghatak A.T. Miller R.L. Anaphylaxis in the United States: An investigation into its epidemiology. Arch Intern Med. 2001; 161: 15-21 Crossref PubMed Scopus (359) Google Scholar , 15 Takakura K. Mizogami M. Fukuda S. Protamine sulfate causes endothelium-independent vasorelaxation via inducible nitric oxide synthase pathway. Can J Anaesth. 2006; 53: 162-167 Crossref PubMed Scopus (15) Google Scholar , 16 Viaro F. Dalio M.B. Evora P.R. Catastrophic cardiovascular adverse reactions to protamine are nitric oxide/cyclic guanosine monophosphate dependent and endothelium mediated: Should methylene blue be the treatment of choice?. Chest. 2002; 122: 1061-1066 Crossref PubMed Scopus (65) Google Scholar Pro: Methylene Blue as a Rescue Therapy for Vasoplegia After Cardiac SurgeryJournal of Cardiothoracic and Vascular AnesthesiaVol. 25Issue 4PreviewCARDIAC SURGERY may be complicated by an exaggerated systemic inflammatory response accompanied by loss of vascular smooth muscle tone and severe vasodilation (vascular paralysis or vasoplegia). Vasoplegia has been defined according to the following set of hemodynamic criteria: mean arterial pressure <50 mmHg, systemic vascular resistance <800 dynes · s · cm−5, cardiac index >2.5 L/min/m2, right atrial pressure <5 mmHg, and left atrial pressure <10 mmHg during the infusion of a vasoconstrictor such as norepinephrine. Full-Text PDF