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Refractory Hypotension...Vasoplegic syndrome...part1



Unexpected refractory hypotension under general anesthesia is an increasingly recognized perioperative issue.

  One cause for this type of hypotension is vasoplegic syndrome (VS). It is most commonly seen during cardiac surgery, but can occur during any anesthetic. 
It is characterized by severe hypotension refractory to catecholamine therapy in the absence of other identifiable causes for hypotension.

 While there is no standardized definition for VS, some researchers have defined it as a mean arterial pressure <50mmHg with a cardiac index >2.5 L/min x m2 and a low systemic vascular resistance despite adrenergic vasopressor administration.

 The incidence of VS in cardiac surgical patients is 8% to 10 %, but may increase to upwards of 50% of patients taking renin angiotensin system (RAS) antagonists.2
 In cardiac surgical patients with persistent hypotension into the postoperative period, the associated mortality approaches 25%.3
While RAS antagonists and their causal association with VS will be the focus of this review, many other risk factors exist. They include, beta-blockers, calcium channel blockers, protamine use, myocardial dysfunction, diabetes mellitus, heart transplant,presence of pre-cardiopulmonary bypass (CPB) hemodynamic instability, valvular and heart failure surgery, increased duration of CPB, or ventricular assist device insertion.


1. Shanmugam G. Vasoplegic syndrome—the role of methylene blue.
European J of Cardio-thoracic Surgery 2005; 28:705-710.
2. Mekontso-Dessap A, Houel R, Soustelle C, Kirsch M, Thebert D, Loisance DY. Risk factors for post-cardiopulmonary bypass vasoplegia in patients with preserved left ventricular function.
 Ann Thorac Surg 2001;71:1428-1432.
3. Gomes WJ, Carvalho AC, Palma JH, Teles CA, Branco JN, Silas MG, Buffolo E. Vasoplegic syndrome after open heart surgery. J Cardiovasc Surg 1998;39:619-623.


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