(191) Correlation of Clinical Outcomes With Timing of Angiotensin II Initiation

Introduction: Angiotensin II (Ang II) is a novel vasopressor that targets non-catecholamine receptors providing vasoconstriction in patients with refractory hypotension. At Virginia Commonwealth University Health System (VCUHS), an Ang II protocol is utilized to guide use; criteria include cardiac surgery patients with hypotension despite a baseline vasopressor requirement of > 0.3 mcg/kg/min norepinephrine equivalents (NEE) and clinical signs of distributive shock. There is, however, minimal published guidance on timing of Ang II initiation for patients with high vasopressor requirements. The primary objective of this study was to evaluate clinical outcomes in correlation with timing of Ang II initiation. The secondary outcome was to evaluate compliance with the VCUHS Ang II protocol.

Methods: A single center, retrospective chart review was conducted from January 1, 2020 to June 30, 2023 and included all patients ≥ 18 years old who received Ang II. Data collection included demographics, clinical data, and norepinephrine equivalents (NEE) and mean arterial pressure (MAP) prior to the start of Ang II as well as hourly intervals for six hours, hour 12, and hour 24 following Ang II initiation.

Results: This study evaluated 15 patients who had a median age of 57 years. The most common indication for Ang II was cardiac surgery requiring cardiopulmonary bypass (n = 9, 60%).

Of 15 patients receiving Ang II, 5 patients (33.3%) achieved 28-day survival following angiotensin II administration. At baseline, patients achieving 28-day survival were on vasopressor therapy at a dose of 0.417 mcg/kg/min NEE for a median of 4.9 hours prior to Ang II initiation compared to 0.692 mcg/kg/min NEE for a median of 9.98 hours in those not reaching 28-day survival. Additionally, 80% (n=4) of patients surviving to day 28 had a blood pressure response of at least 10 mm Hg at hour 3 compared to only 20% (n=2) in the non-surviving group. For protocol compliance, 10 patients (66.7%) had a MAP of < 60 mmHg prior to Ang II initiation and 13 (86.7%) had NEE of >0.3 mg/kg/min.

Conclusions: Our data demonstrates a possible correlation between achievement of 28-day survival and initiation of angiotensin II earlier in vasopressor therapy. A study with a larger number of patients is warranted to evaluate this correlation further