Angiotensin II for Vasodilatory Hypotension in Patients Requiring Mechanical Circulatory Support

The Effects of Angiotensin II versus Norepinephrine on Pulmonary Vascular Resistance in Cardiac Surgery: Post Hoc Analysis of a Randomized Controlled Trial

OBJECTIVES

To assess whether angiotensin II infusion increases pulmonary vascular resistance (PVR) relative to norepinephrine.

DESIGN

Secondary analysis of a double-blinded randomized feasibility study.

SETTING

Two tertiary metropolitan hospitals in Melbourne, Australia.

PARTICIPANTS

Fifty-eight adult patients undergoing cardiac surgery using cardiopulmonary bypass with an elevated risk of acute kidney injury (AKI).

INTERVENTIONS

Angiotensin II infusion compared with norepinephrine infusion.

MEASUREMENTS AND MAIN RESULTS

There was no significant difference in the primary outcome of PVR both intraoperatively and postoperatively between the angiotensin II group and the norepinephrine group. The study drug (angiotensin II or norepinephrine) infusion rate was associated with a small increase in PVR (β = 0.08; p = 0.01). The strongest association with PVR was the random effect (ie, patient effect) (p < 0.001). This effect was consistent across secondary outcomes. Randomization to norepinephrine instead of to angiotensin II was associated with reduced mean systemic arterial to mean pulmonary arterial pressure ratio postoperatively (β = -0.65; p = 0.01).

CONCLUSIONS

The results of this study suggest that in cardiac surgery patients and at doses used in the prior feasibility study, angiotensin II did not have significant effects on the pulmonary vasculature compared with norepinephrine. Moreover, at doses used in this study, neither drug appeared to have a substantial effect on the pulmonary circulation relative to surgical and patient factors.

The renin-angiotensin-aldosterone-system in sepsis and its clinical modulation with exogenous angiotensin II

Dysregulation of the renin-angiotensin-aldosterone-system (RAAS) in sepsis is a complex and early phenomenon with a likely significant contribution to organ failure and patient outcomes. A better understanding of the pathophysiology and intricacies of the RAAS in septic shock has led to the use of exogenous angiotensin II as a new therapeutic agent. In this review, we report a multinational and multi-disciplinary expert panel discussion on the role and implications of RAAS modulation in sepsis and the use of exogenous angiotensin II. The panel proposed guidance regarding patient selection and treatment options with exogenous angiotensin II which should trigger further research.

Angiotensin-II for vasoplegia following cardiac surgery

INTRODUCTION

The objective of this study was to describe the implementation and outcomes of a protocol outlining angiotensin-II utilization for vasoplegia following cardiac surgery.

METHODS

This was a retrospective chart review at a single-center university hospital. Included patients received angiotensin-II for vasoplegia refractory to standard interventions, including norepinephrine 20 mcg/min and vasopressin 0.04 units/min, following cardiac surgery between April 2021 and April 2022.

RESULTS

30 patients received angiotensin-II for refractory vasoplegia. Adjunctive agents at angiotensin-II initiation included corticosteroids (26 patients; 87%), epinephrine (26 patients; 87%), dobutamine (17 patients; 57%), dopamine (9 patients; 30%), milrinone (2 patients; 7%), and hydroxocobalamin (4 patients; 13%). At 3 hours, the median mean arterial pressure increased from baseline (70 vs 61.5 mmHg, p = .0006). Median norepinephrine doses at angiotensin-II initiation, 1 hour, 3 hours, and angiotensin-II discontinuation were 0.22, 0.16 (p = .0023), 0.10 (p < .0001), and 0.07 (p < .0001) mcg/kg/min. Median dobutamine doses decreased throughout angiotensin-II infusion from eight to six mcg/kg/min (p = .0313). Other vasoactive medication doses were unchanged. Three patients (10%) subsequently received hydroxocobalamin. Thirteen (43.3%) and five (16.7%) patients experienced mortality by day 28 and venous or arterial thrombosis events, respectively.

CONCLUSIONS

The administration of angiotensin-II to vasoplegic patients following cardiac surgery was associated with increased mean arterial pressure, reduced norepinephrine dosages, and reduced dobutamine dosages.

Angiotensin II-Real-Life Use and Literature Review

Angiotensin II is a recently introduced vasopressor, which has been available since 2017. The novelty and the relatively high cost of angiotensin II currently limit its broader application. It induces vasoconstriction by activating the renin-angiotensin-aldosterone system and is currently the sole vasopressor functioning through this pathway. Beyond vasoconstriction, angiotensin II also affects various other physiological processes. Current evidence supports its use in managing vasoplegic and cardiogenic shock in patients who are unresponsive to catecholamines and vasopressin. However, due to limited data, the optimal timing for initiating therapy with angiotensin II, strategies for combining it with other vasopressors, and strategies for its discontinuation remain unclear. Ongoing and planned studies aim to address some of these uncertainties. This article reviews the physiological and pathophysiological effects of angiotensin II, describes its pharmacology, and provides a narrative review of the current literature.

Clinical Outcomes of Angiotensin II Therapy in Vasoplegic Shock: A Systematic Review and Meta-Analysis

BACKGROUND

Angiotensin II is a peptide hormone vasopressor that activates angiotensin type 1 (AT1) receptors leading to vasoconstriction, the augmentation of arterial blood pressure (ABP), and organ perfusion. Angiotensin II was found to increase the ABP in catecholamine-refractory vasodilatory shock. Whether this effect improves the chances of survival or not remains inconclusive. Therefore, we conducted a systematic review and meta-analysis to evaluate the efficacy and safety of angiotensin II in vasoplegic shock.

OBJECTIVES

To evaluate the clinical significance of angiotensin II effects in vasoplegic shock concerning the hemodynamic impact, mortality outcomes, and side effects.

METHODS

Following PRISMA guidelines, we searched PubMed and EMBASE for experimental and observational studies published in English exploring the clinical outcomes of angiotensin II use in vasodilatory shock till 1 July 2024. Two independent authors assessed the quality and risk of bias of the included studies. A random effect model (Mantel-Haenszel) was used to combine data. The primary outcome was in-hospital mortality associated with angiotensin II use in comparison to standard therapy, while the secondary outcomes were mean arterial pressure (MAP) change, multi-organ failure (MOF), and the incidence of atrial fibrillation (AF). The Q test and I2 were used to examine heterogeneity, with I2 > 50% indicating marked heterogeneity.

RESULTS

A total of eight studies (n = 974) comparing angiotensin II to standard therapy in vasoplegic shock were included in the systematic review, with three studies comprising 461 patients included in the final analysis of the primary outcome. Only one study evaluated the use of angiotensin II as a primary vasopressor, while the rest reported angiotensin II use in catecholamine-refractory vasodilatory shock. Overall, angiotensin II use was associated with similar in-hospital mortality compared to standard therapy (risk ratio [RR] = 0.83; 95% CI, 0.68-1.02, I2 = 0%). Likewise, there was no difference in MOF and AF (MOF: RR = 1.01; 95% CI, 0.61-1.65, I2 = 0%; AF: RR = 1.27; 95% CI, 0.38-4.23, I2 = 5%). However, angiotensin II use demonstrated a significant MAP increase (mean difference = -9.60; 95% CI, -9.71, -9.49, I2 = 0%).

CONCLUSIONS

In vasodilatory shock, angiotensin II use demonstrated comparable in-hospital mortality compared to standard therapy. Nevertheless, it resulted in significant MAP change, which may encourage clinicians to use it in cases of profound hypotension.

ANGIOTENSIN II IN THE TREATMENT OF DISTRIBUTIVE SHOCK: A SYSTEMATIC-REVIEW AND META-ANALYSIS

ABSTRACT

Objective: While nonnorepinephrine vasopressors are increasingly used as a rescue therapy in cases of norepinephrine-refractory shock, data on their efficacy are limited. This systematic review and meta-analysis aims to synthesize existing literature on the efficacy of angiotensin II (ATII) in distributive shock. Methods: We preregistered our meta-analysis with PROSPERO (CRD42023456136). We searched PubMed, Scopus, and gray literature for studies presenting outcomes on ATII use in distributive shock. The primary outcome of the meta-analysis was all-cause mortality. We used a random effects model to calculate pooled risk ratio (RR) and 95% confidence intervals (CIs). Results: By incorporating data from 1,555 patients included in 10 studies, we found that however, all-cause mortality was similar among patients receiving ATII and controls (RR = 1.02; 95% CI: 0.89 to 1.16, P = 0.81), the reduction in norepinephrine or norepinephrine-equivalent dose at 3 h after treatment initiation was greater among patients receiving ATII (MD = -0.06; 95% CI: -0.11 to -0.02, P = 0.008), while there were no higher rates of adverse events reported among ATII patients. Conclusions: While ATII did not reduce mortality among distributive shock patients, it allowed for significant adjunctive vasopressor reduction at 3 h without an increase in reported adverse events, deeming it a viable alternative for the increasingly adopted multimodal vasopressor for minimizing catecholamine exposure and its adverse events.

Diagnosis and Management of Vasoplegia in Temporary Mechanical Circulatory Support: A Narrative Review

Refractory vasodilatory shock, or vasoplegia, is a pathophysiologic state observed in the intensive care unit and operating room in patients with a variety of primary diagnoses. Definitions of vasoplegia vary by source but are qualitatively defined clinically as a normal or high cardiac index and low systemic vascular resistance causing hypotension despite high-dose vasopressors in the setting of euvolemia. This definition can be difficult to apply to patients undergoing mechanical circulatory support (MCS). A large body of mostly retrospective literature exists on vasoplegia in the non-MCS population, but the increased use of temporary MCS justifies an examination of vasoplegia in this population. MCS, particularly extracorporeal membrane oxygenation, adds complexity to the diagnosis and management of vasoplegia due to challenges in determining cardiac output (or total blood flow), lack of clarity on appropriate dosing of noncatecholamine interventions, increased thrombosis risk, the difficulty in determining the endpoints of adequate volume resuscitation, and the unclear effects of rescue agents (methylene blue, hydroxocobalamin, and angiotensin II) on MCS device monitoring and function. Care teams must combine data from invasive and noninvasive sources to diagnose vasoplegia in this population. In this narrative review, the available literature is surveyed to provide guidance on the diagnosis and management of vasoplegia in the temporary MCS population, with a focus on noncatecholamine treatments and special considerations for patients supported by extracorporeal membrane oxygenation, transvalvular heart pumps, and other ventricular assist devices.

Management of Vasoplegic Shock in the Cardiovascular Intensive Care Unit after Cardiac Surgery

Vasoplegic shock after cardiac surgery is characterized by hypotension, a high cardiac output, and vasodilation. Much of the understanding of this pathologic state is informed by the understanding of septic shock. Adverse outcomes and mortality are increased with vasoplegic shock. Early recognition and a systematic approach to its management are critical. The need for vasopressors to sustain an adequate blood pressure as well as pharmacologic adjuncts to mitigate the inflammatory inciting process are necessary. The rationale behind vasopressor escalation and consideration of adjuncts are discussed.

Intraoperative arterial pressure management: knowns and unknowns

Preventing postoperative organ dysfunction is integral to the practice of anaesthesia. Although intraoperative hypotension is associated with postoperative end organ dysfunction, there remains ambiguity with regards to its definition, targets, thresholds for initiating treatment, and ideal treatment modalities.