The Vexing Problem of Vasoplegia SCOTT siLVESTRY md florida Hospital transplant institute

No relevant disclosures

Vasoplegia Unexpected refractory hypotension from a severe SIRS response following cardiac surgery involving cardiopulmonary bypass (CPB) 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.

No Standard Definition Form of vasodilitory shock that occurs in the early postoperative period (< 6 hours after weaning from CBP), manifested by: Hypotension [MAP < 70 without vasoactive agents] Tachycardia Normal or increased cardiac output [CI > 2.5 L / min / m2] Low systemic vascular resistance [SVR < 800 dynes-s · cm−5 · m−2 ]

Vasoplegia Syndrome Pts have poor prognosis, Especially norepinephrine-resistant vasoplegia. Catecholamine resistant vasoplegia lasting for more than 36 to 48 hours has a mortality rate as high as 25%. Associated with longer hospital stays, prolonged ICU stays, prolonged mechanical ventilation and more sternal infections In all the forms of vasodilatory shock that have been examined, plasma catecholamine concentrations are markedly increased 4,15 and the renin–angiotensin system is activated.

The steps involved in vasoconstriction are shown in blue, and the steps involved in vasodilatation are shown in red. The phosphorylation (P) of myosin is the critical step in the contraction of vascular smooth muscle. By way of second messengers, vasoconstrictors such as angiotensin II and norepinephrine induce an increase in the cytosolic calcium concentration, which activates myosin kinase. Vasodilators such as atrial natriuretic peptide and nitric oxide activate myosin phosphatase and, by dephosphorylating myosin, cause vasorelaxation. The plasma membrane is shown at a resting potential (plus signs). The abbreviation cGMP denotes cyclic guanosine monophosphate.

A (n 16), patients discontinued ramipril 24 hours before surgery; Prophylactic Vasopressin in Patients Receiving the Angiotensin-Converting Enzyme Inhibitor Ramipril Undergoing Coronary Artery Bypass Graft Surgery A (n 16), patients discontinued ramipril 24 hours before surgery; B (n 16), patients continued ramipril until the morning of surgery; C (n 15), patients continued ramipril until the morning of surgery and received vasopressin infusion (0.03 U/min) from the onset of rewarming Journal of Cardiothoracic and Vascular Anesthesia, Vol 24, No 2 (April), 2010: pp 230-238

Preoperative Methylene Blue Administration in Patients at High Risk for Vasoplegic Syndrome During Cardiac Surgery One hundred patients scheduled for coronary artery bypass graft surgery who were at high risk for vasoplegia because they were preoperatively using angiotensin-converting enzyme inhibitors, calcium channel blockers, and heparin were randomly assigned to either receive preoperative methylene blue (group 1, n = 50) or not receive it (group 2, controls, n = 50). Methylene blue (1% solution) was administered intravenously at a dose of 2 mg/kg for more than 30 minutes, beginning in the intensive care unit 1 hour before surgery. Ozal et al ATS 79(5)1615-1619 2005.

Resuscitation goals Early vasopressor use Vasopressin: Infusion rates up to 0.06 units/min (maximum) – first line agent Norepinephrine: Infusion rates starting at 0.05 mcg/kg/min – second line agent, as these patients may be refractory to refractory catecholamines. Other suggested treatments Methylene blue: 2 mg/kg IV Correct underlying causes for a metabolic acidosis Target MAP between 70-80  Intravascular volume expansion – careful administration to avoid excessive volume loading

Statement 6: (grade C, level 2) In patients with vasodilatory shock requiring vasopressor support and with low filling pressures methylene blue may reduce the duration of the vasoplegic syndrome and the need for norepinephrine infusion. Methylene blue may also reduce mortality and morbidity in these patients. Statement 7: (grade C, level 2) Prophylactic use of methylene blue may reduce postoperative CPB hypotension and vasopressor requirements. Methylene blue in this setting may also be associated with shorter length of stay in the ICU. Statement 8: (grade C, level 2) Prophylactic use of vasopressin reduces postoperative CPB hypotension and vasopressor requirements. Vasopressin in this setting may also be associated with shorter intubation time and length of stay in the ICU.

Role of EMCO/MCS ? LVAD/BIVAD ECMO Case Reports Treated 2 patients post OHT Normal Graft function/profound hypotension Profound Acidosis 36 hrs ECMO Flows 6-8 liters Resolution of acidosis/hypotension Both survived with normal function

Summary Vasoplegia remains hard to predict and devastating in its impact. Consider Discontinuing ACEi prior to cardiac surgery. Consider prophylactic Vasopression/MB in high risk candidates. Consider escalation of MCS ( ECMO/RVAD) in appropriate scenarios (LVAD, Heart transplant).

Thank you