(193) Midodrine to Facilitate Vasopressor Weaning in Patients Undergoing Cardiovascular Surgery

Introduction: Patients with adequate cardiac function and hemostasis may require low-dose intravenous vasopressors for vasoplegia after cardiac surgery. Midodrine may be suitable to facilitate separation from vasopressors in such patients and expedite ICU discharge, however application is often extrapolated from experience in other populations. The goal of this study was to assess the utility of an implementation bundle designed to optimize midodrine use following cardiac surgery.

Methods: This was a single center, before-after study of adult patients who received midodrine within 48-hours after non-emergent cardiac surgery. Patients were included if they were extubated within 6 hours of ICU arrival, had a cardiac index > 2.2 L/min/m2 without inotropic support, were adequately fluid resuscitated, and required low-dose vasopressors (norepinephrine ≤ 0.05 mcg/kg/min, vasopressin ≤ 0.04 u/min). Patients undergoing emergency surgery, cardiothoracic transplantation, or receiving mechanical circulatory support were excluded. The implemented bundle included an integrated electronic health record order panel for midodrine 10 mg every 6 hours, education on midodrine pharmacology, and optimization of automated dispensing cabinets in the ICU . The primary outcome was time to vasopressor discontinuation.

Results: A total of 68 patients were evaluated with 50 before the bundle and 18 after implementation. Midodrine was initiated a median 25.4 (IQR 18.9-39.9) hours following ICU arrival at a median norepinephrine-equivalent dose of 0.04 (IQR 0.02-0.10) mcg/kg/min. In the pre-implementation group, most (70%) midodrine orders had suboptimal dosing frequencies (e.g., tid meals: 0800-1200-1700) resulting in extended intervals between doses, while the post-implementation group had consistent around-the-clock dosing (i.e., q6h). Following implementation, the time to vasopressor discontinuation numerically decreased from 12.6 to 9.7 hours (p = 0.23), no adverse effects were noted, and all patients were weaned off midodrine before discharge from the hospital.

Conclusions: Implementation of a bundle to optimize midodrine prescriptive practices may offer a strategy to reduce time on intravenous vasopressors in patients with non-cardiogenic, non-hypovolemic hypotension after cardiac surgery.