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Vasopressin Versus Norepinephrine in Patients with Vasoplegic Shock After Cardiac Surgery
Vasopressin Versus Norepinephrine in Patients with Vasoplegic Shock After Cardiac Surgery
Ludhmila AH, Vincent JL, Galas FR, et al. Anesthesiology. 2017; 126: 85-93.
Study Question: Is vasopressin superior to norepinephrine for the treatment of vasoplegic syndrome after cardiac surgery?
Study Description: This single-center, double-blind trial of adult cardiac surgery patients randomized patients with vasoplegic shock (MAP < 65mmHg resistant to 1000mL fluid challenge and cardiac index > 2.2 L/min/m2) to receive either vasopressin or norepinephrine. Vasopressin ranges were 0.01 to 0.06 units/min, and norepinephrine ranges were 10 – 60 mcg/min. If target MAP was not achieved with the study drug, open label norepinephrine was initiated. All patients received 10 mg/kg of methylprednisolone intraoperatively. The primary endpoint was a composite of mortality or severe complications (stroke, mechanical ventilation > 48 hours, sternal wound infections, re-operation, or renal failure). Secondary endpoints included 30-day incidence of septic shock, arrhythmias, duration of mechanical ventilation, and length of stay.
Results: A total of 330 patients were randomized. The primary outcome occurred in 74 patients in the norepinephrine group and 48 patients in the vasopressin group (HR 0.55, 95%CI 0.38 – 0.80, p = 0.0014). The use of vasopressin conferred an absolute risk reduction of 16.8% indicating a number needed to treat of 6 to avoid the composite outcome. Notably, vasopressin use was associated with a significant reduction in the occurrence of acute renal failure, shorter vasopressor duration and decreased length of stay. No significant differences between study groups in MAP, infection, septic shock, or ventricular arrhythmias at 30 days were observed; however, the incidence of atrial fibrillation was lower in the vasopressin group.
Conclusion(s): Vasopressin may be a preferable agent to norepinephrine for the treatment of vasoplegic shock due to its association with improved outcomes.
Perspective: The unique pathophysiology of vasoplegic shock suggests a specific role of vasopressin, especially given its neutral effects on myocardial oxygen demand and limited arrhythmogenic effects. The dose range of vasopressin exceeded 0.04 units/min, a potential safety concern, though no difference in mesenteric ischemia was observed. Results suggest equal efficacy of norepinephrine and vasopressin to increase MAP in vasoplegic shock, but the superior safety profile of vasopressin observed makes it an attractive first-line option. Widespread applicability is limited due to the single-center design and institutional protocols which included high-dose corticosteroids.