Outcomes in Patients with Vasodilatory Shock and Renal Replacement Therapy Treated with Intravenous Angiotensin II

THE EFFECT OF CATECHOLAMINE VERSUS NONCATECHOLAMINE VASOPRESSORS ON RENAL FUNCTION AND RECOVERY IN VASODILATORY SHOCK: A SYSTEMATIC REVIEW OF PRECLINICAL AND CLINICAL STUDIES

ABSTRACT

Background: Acute kidney injury (AKI) is a common complication of vasodilatory shock. AKI is associated with an increased risk of death, prolonged hospital stays, and subsequent transition to chronic kidney disease. Catecholamines have historically been used as the first-line vasopressors for vasodilatory shock; however, they may adversely affect renal function and recovery. Objectives: To compare the effects of catecholamine and noncatecholamine vasopressors on AKI risk and recovery in preclinical and clinical studies of vasodilatory shock. Methods: MEDLINE, Embase, and Cochrane Central Register of Controlled Trials were systematically searched to identify studies reporting renal outcomes associated with catecholamine (norepinephrine, epinephrine, metaraminol, phenylephrine, dopamine) and noncatecholamine vasopressors (vasopressin, angiotensin II), in preclinical models or adult cohorts of vasodilatory shock. Two independent reviewers screened studies and extracted data using a prespecified form for qualitative synthesis and risk of bias assessment. Results: Of 3,504 citations, 90 studies were eligible for inclusion: 41 preclinical studies, 17 nonrandomized clinical studies, 28 randomized clinical studies, and 4 post-hoc analyses. Risk of bias was generally low in preclinical studies and low to moderate in clinical studies. In preclinical studies, catecholamine vasopressors exacerbated medullary hypoxia and intrarenal inflammation compared to noncatecholamine vasopressors. In clinical studies, catecholamines were associated with higher serum creatinine, lower urine output, and increased requirements for renal replacement therapy compared to noncatecholamine vasopressors. In patients on high-dose catecholamines, adjunctive angiotensin II was associated with improved renal replacement therapy liberation. Conclusion: Preclinical and clinical studies suggest that noncatecholamine vasopressors may confer renal benefits compared to catecholamine vasopressors. These hypothesis-generating observations suggest the need for comparative studies focused on renal outcomes. Systematic Review Registration : PROSPERO 2024 CRD42024527773.

An index of the initial blood pressure response to angiotensin II treatment and its association with clinical outcomes in vasodilatory shock

BACKGROUND

No standardized index exists to assess cardiovascular responsiveness to angiotensin-II. We hypothesized that a standardized index of initial blood pressure response to angiotensin-II treatment would be associated with clinical outcomes.

METHODS

Using data from the Angiotensin Therapy for High Output Shock (ATHOS-3) trial, we developed an Angiotensin-II Initial MAP Response Index of Treatment Effect (AIMRITE) defined as (MAP at hr1 - MAP at baseline)/study drug dose. We assessed AIMRITE continuously and, based on observed distributions, we additionally categorized patients as "responsive" or "resistant", with responsiveness defined by an AIMRITE ≥ 0.90 mmHg/ng/kg/min. The primary clinical outcome was 28-day mortality. Secondary outcomes included days alive and vasopressor- or ventilator- or renal replacement therapy-free at day-7. Biological outcomes included baseline renin, angiotensin-II, and renin/angiotensin-II ratio, and their change at hr3.

RESULTS

Of 158 placebo patients, as expected, 157 (99%) had AIMRITE < 0.90 mmHg/ng/kg/min (median AIMRITE 0.02; IQR - 0.03-0.10). In contrast, 163 patients assigned to angiotensin-II had a median AIMRITE of 1.43 mmHg/ng/kg/min (IQR 0.35-2.83). Of these, 97 (60%) were responsive (median AIMRITE 2.55; IQR 1.66-4.12) and 66 (40%) were resistant (median AIMRITE 0.24; IQR 0.10-0.52). Each 1.0-unit increase in AIMRITE was associated with a 16% lower hazard of death (HR: 0.84 per-mmHg/ng/kg/min [95% CI 0.74-0.95], p = 0.0062). Responsive patients had half the mortality hazard than resistant patients (HR: 0.50 [95% CI 0.32-0.78], p = 0.0026) and placebo patients (HR 0.58 [95% CI 0.40-0.86], p = 0.0064). Resistant patients had a similar mortality hazard to placebo (HR 1.17 [95% CI 0.80-1.72], p = 0.41). Compared to resistant patients, responsive patients had lower baseline renin and renin/angiotensin-II ratio, but a greater decrease in both at hr3. When stratified by baseline renin level, mortality was highest in placebo patients with high renin (69%) and angiotensin-II resistant patients with low renin (61%).

CONCLUSIONS

Among patients with catecholamine-refractory vasodilatory shock treated with angiotensin-II, the AIMRITE was associated with mortality at day-28. Responsive angiotensin-II patients had higher survival versus both angiotensin-II resistant patients and those treated with placebo plus standard vasopressors. This index may serve as a prognostic indicator and early identifier of patients most likely to benefit from angiotensin-II.

Kinetics of Renin Concentrations in Infants Undergoing Congenital Cardiac Surgery

BACKGROUND

Elevated renin has been shown to predict poor response to standard vasoactive therapies and is associated with poor outcomes in adults. Similarly, elevated renin was associated with mortality in children with septic shock. Renin concentration profiles after pediatric cardiac surgery are unknown. The purpose of this study was to characterize renin kinetics after pediatric cardiac surgery.

METHODS

Single-center retrospective study of infants who underwent cardiac surgery with cardiopulmonary bypass (CPB) utilizing serum samples obtained in the perioperative period to measure plasma renin concentrations (pg/mL). Time points included pre-bypass and 1, 4, and 24 h after initiation of CPB.

RESULTS

Fifty patients (65% male) with a median age 5 months (interquartile range (IQR) 3.5, 6.5) were included. Renin concentrations peaked 4 h after CPB. There was a significant difference in preoperative and 4 h post-CPB renin concentration (4 h post-CPB vs preoperative: mean difference 100.6, 95% confidence interval (CI) 48.9-152.4, P < .001). Median renin concentration at 24 h after CPB was lower than the preoperative baseline.

CONCLUSIONS

We describe renin kinetics in infants after CPB. Future studies based on these data can now be performed to evaluate the associations of elevated renin concentrations with adverse outcomes.

Evaluation of Angiotensin II in Patients With Catecholamine-Resistant Vasodilatory Shock Requiring Continuous Renal Replacement Therapy (ANGEL CRRT)

OBJECTIVE

To compare clinical outcomes of patients with catecholamine-resistant vasodilatory shock (CRVS) receiving continuous renal replacement therapy who receive adjunctive angiotensin II (ANGII) to those who do not.

DESIGN

Retrospective cohort analysis.

SETTING

Multicenter, single health system consisting of one academic medical center and four community hospitals.

PARTICIPANTS

Critically ill adult patients with CRVS (norepinephrine or equivalent dose ≥0.5 mcg/kg/min).

INTERVENTIONS

Adjunctive ANGII versus standard-of-care (SOC) vasopressors alone (norepinephrine, epinephrine, vasopressin, phenylephrine, dopamine).

MEASUREMENTS AND MAIN RESULTS

The primary outcome was intensive care unit mortality. Secondary outcomes included 30-day mortality, Sequential Organ Failure Assessment (SOFA) score at 72 hours, time to shock resolution, and adverse effects. A multivariate logistic regression was used for the primary analysis. The study included 265 patients, of which 70 received ANGII and 195 received SOC. Intensive care unit and 30-day mortality were lower in patients that received ANGII (61.4% v 75.4%, adjusted odds ratio 0.438, 95% confidence interval: 0.239-0.805, p = 0.008; and 67.1% v 78.5%, adjusted odds ratio 0.479, 95% confidence interval: 0.256-0.898, p = 0.022). Differences in time to shock reversal and SOFA score at 72 hours were not statistically significant. The adverse effects evaluated were not statistically significant, apart from an increase in fungal infections in the ANGII group (17.1% v 7.2%, p = 0.016).

CONCLUSIONS

ANGII was associated with lower mortality in patients who received renal replacement therapy compared to SOC. This evaluation reaffirms a subgroup of patients that may benefit from the addition of ANGII.

Acute kidney injury

Acute kidney injury (AKI) is a common, heterogeneous, multifactorial condition, which is part of the overarching syndrome of acute kidney diseases and disorders. This condition's incidence highest in low-income and middle-income countries. In the short term, AKI is associated with increased mortality, an increased risk of complications, extended stays in hospital, and high health-care costs. Long-term complications include chronic kidney disease, kidney failure, cardiovascular morbidity, and an increased risk of death. Several strategies are available to prevent and treat AKI in specific clinical contexts. Otherwise, AKI care is primarily supportive, focused on treatment of the underlying cause, prevention of further injury, management of complications, and short-term renal replacement therapy in case of refractory complications. Evidence confirming that AKI subphenotyping is necessary to identify precision-oriented interventions is growing. Long-term follow-up of individuals recovered from AKI is recommended but the most effective models of care remain unclear.

Higher circulating ACE2 and DPP3 but reduced ACE and angiotensinogen in hyperreninemic sepsis patients

Sepsis and septic shock are global healthcare problems associated with high mortality rates. Activation of the renin-angiotensin-aldosterone system (RAAS) is an early event in sepsis, and elevated renin may be predictive of worse outcomes. In a subset of sepsis patients enrolled in the Vitamin C, Thiamine and Steroids in Sepsis (VICTAS) trial, elevated levels of active renin (median value > 189 pg/mL or 5.1 pM) at baseline (day 0) were strongly associated with mortality; however, corresponding plasma levels of the vasopressor hormone Angiotensin II were not substantially increased nor was Angiotensin II associated with disease severity. The current study assessed RAAS components that may impact the Angiotensin II response in control subjects, normal renin sepsis (NRS, renin < 5.1 pM) and high renin sepsis (HRS, renin > 5.1 pM) patients. NRS and HRS subjects exhibited a similar reduction in ACE (40%), but increased levels of ACE2 and DPP3. The ACE to DPP3 ratio was higher in controls but this relationship was reversed in both NRS and HRS subjects. Intact angiotensinogen was 50% lower in the HRS than control or NRS subjects, whereas the intact angiotensinogen to renin ratio was <10% of control or NRS subjects. We conclude that altered expression of ACE, ACE2, DPP3 and angiotensinogen may attenuate the expected increase in Angiotensin II, particularly in sepsis subjects with high renin concentrations.

Haemodynamic management of septic shock

Septic shock is a significant challenge in the management of patients with burns and traumatic injuries when complicated by infection, necessitating prompt and effective haemodynamic support. This review provides a comprehensive overview of current strategies for vasopressor and fluid management in septic shock, with the aim to optimize patient outcomes. With regard to vasopressor management, we elaborate on the pharmacologic profiles and clinical applications of catecholamines, vasopressin derivatives, angiotensin II, and other vasoactive agents. Noradrenaline remains central to septic shock management. The addition of vasopressin, when sequentially added to noradrenaline, offers a non-catecholaminergic vasoactive effect with some clinical benefits and risks of adverse effects. Emerging agents such as angiotensin II and hydroxocobalamin are highlighted for their roles in catecholamine-resistant vasodilatory shock. Next, for fluid management, crystalloids are currently preferred for initial resuscitation, with balanced crystalloids showing benefits over saline. The application of albumin in septic shock warrants further research. High-quality evidence does not support large-volume fluid resuscitation, and an individualized strategy based on haemodynamic parameters, including lactate clearance and capillary refill time, is recommended. The existing knowledge suggests that early vasopressor initiation, particularly noradrenaline, may be critical in cases where fluid resuscitation takes inadequate effect. Management of refractory septic shock remains challenging, with novel agents like angiotensin II and methylene blue showing potential in recent studies. In conclusion, Further research is needed to optimize haemodynamic management of septic shock, particularly in developing novel vasopressor usage and fluid management approaches.

How Would We Prevent Our Own Acute Kidney Injury After Cardiac Surgery?

Acute Kidney Injury (AKI) is a common complication after cardiac surgery affecting up to 40% leading to increased morbidity and mortality. To date, there is no specific treatment for AKI, thus, clinical research efforts are focused on preventive measures. The only pharmacological preventive intervention that has demonstrated a beneficial effect on AKI in a high-quality, double-blind, randomized controlled trial is a short perioperative infusion of a balanced mixture of amino acid solution. Amino acid infusion reduced the incidence of AKI by recruiting renal functional reserve and, therefore, increasing the glomerular filtration rate. The beneficial effect of amino acids was further confirmed for severe AKI and applied to patients with chronic kidney disease. Among non-pharmacological interventions, international guidelines on AKI suggest the implementation of a bundle of good clinical practice measures to reduce the incidence of perioperative AKI or to improve renal function whenever AKI occurs. The Kidney Disease Improving Global Outcomes (KDIGO) bundle includes the discontinuation of nephrotoxic agents, volume status and perfusion pressure assessment, renal functional hemodynamic monitoring, serum creatine, and urine output monitoring, and the avoidance of hyperglycemia and radiocontrast procedures. However, pooled data from a meta-analysis did not find a significant reduction in AKI. The aim of this review is to delineate the most appropriate evidence-based approach to prevent AKI in cardiac surgery patients.

ANGIOTENSIN II FOR CATECHOLAMINE-RESISTANT VASODILATORY SHOCK IN PATIENTS WITH ACUTE KIDNEY INJURY: A POST HOC ANALYSIS OF THE ATHOS-3 TRIAL

ABSTRACT

Objective: The combination of catecholamine-resistant vasodilatory shock and acute kidney injury (AKI) is associated with high morbidity and mortality. The role of angiotensin II (ANGII) in this setting is unclear. Methods: We conducted a post hoc analysis of the Angiotensin II for the Treatment of High-Output Shock (ATHOS) 3 trial which assessed the effect of Intravenous ANG II or placebo in patients with refractory vasodilatory shock in 75 intensive care units across nine countries in North America, Australasia, and Europe. We included patients with all stages AKI at initiation of ANG II or placebo and assessed 28-day mortality as primary outcome. We studied mean arterial pressure (MAP) response and days alive and free from renal replacement therapy (RRT) up to day 7 as secondary outcome. Results: Of 321 ATHOS-3 patients, 203 (63%) had AKI at randomization, with stage 3 AKI being dominant (67%). Median age was 63 years and median APACHE II score was 30. By day 28, overall, 118 (58%) of patients had died (53% with ANGII vs. 63% with placebo, hazard ratio = 0.75, 95% CI [0.52-1.08], P = 0.121). Among AKI stage 3 patients, however, ANGII was associated with significantly lower mortality (48% vs. 67%, hazard ratio = 0.57, 95% CI [0.36-0.91], P = 0.024). Additionally, in this subgroup, compared with placebo, patients receiving ANGII were more likely to achieve a MAP response (P < 0.001) and had more days alive and free from RRT (P < 0.001). Conclusions: Compared with placebo, in patients with catecholamine-resistant vasodilatory shock and stage 3 AKI, ANGII is associated with lower 28-day, greater likelihood of MAP response, and more days alive and free from RRT. These findings support the conduct of future ANGII trials in patients with stage 3 AKI.

New drugs for acute kidney injury

Acute kidney injury (AKI) presents a significant challenge in the management of critically ill patients, as it is associated with increased mortality, prolonged hospital stays, and increased healthcare costs. In certain conditions, such as during sepsis or after cardiac surgery, AKI is one of the most frequent complications, affecting 30%-50% of patients. Over time, even after the resolution of AKI, it can evolve into chronic kidney disease, a leading global cause of mortality, and cardiovascular complications. Despite significant improvement in the care of critically ill patients over the past two decades, the incidence of AKI remains stable, and novel approaches aiming at reducing its occurrence or improving AKI outcomes are still mostly lacking. However, recent insights into the pathophysiology of AKI within critical care settings have shed light on new pathways for both prevention and treatment, providing various new therapeutic targets aimed to mitigating kidney injury. These advancements highlight the intricate and multifaceted nature of the mechanisms underlying AKI, which could explain the challenge of identifying an effective treatment. Among these targets, modulation of the inflammatory responses and the cellular metabolism, hemodynamic regulation and enhancement of cellular repair mechanisms, have emerged as promising options. These multifaceted approaches offer renewed hope for limiting the incidence and severity of AKI in critically ill patients. Several ongoing clinical trials are evaluating the efficacy of these different strategies and we are facing an exiting time with multiple therapeutic interventions being tested to prevent or treat AKI. In this review, we aim to provide a summary of the new drugs evaluated for preventing or treating AKI in critical care and surgical settings.

Non-adrenergic vasopressors for vasodilatory shock or perioperative vasoplegia: a meta-analysis of randomized controlled trials

BACKGROUND

Excessive exposure to adrenergic vasopressors may be harmful. Non-adrenergic vasopressors may spare adrenergic agents and potentially improve outcomes. We aimed to conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the efficacy of non-adrenergic vasopressors in adult patients receiving vasopressor therapy for vasodilatory shock or perioperative vasoplegia.

METHODS

We searched PubMed, Embase, and Cochrane Library for RCTs comparing non-adrenergic vasopressors with adrenergic vasopressors alone or placebo in critically ill or perioperative patients. Each eligible study was categorized into septic shock, cardiac surgery, or non-cardiac surgery. Non-adrenergic vasopressors included vasopressin, terlipressin, selepressin, angiotensin II, methylene blue, and hydroxocobalamin. The primary outcome was mortality at longest follow-up. We conducted a random-effects meta-analysis. We registered the protocol in PROSPERO International Prospective Register of Systematic Reviews (CRD42024505039).

RESULTS

Among 51 eligible RCTs totaling 5715 patients, the predominant population was septic shock in 30 studies, cardiac surgery in 11 studies, and non-cardiac surgery in 10 studies. Cochrane risk-of-bias tool for randomized trials version 2 identified 17 studies as low risk of bias. In septic shock, mortality was significantly lower in the non-adrenergic group (960/2232 [43%] vs. 898/1890 [48%]; risk ratio [RR], 0.92; 95% confidence interval [95% CI], 0.86-0.97; P = 0.03; I2 = 0%), with none of the individual non-adrenergic vasopressors showing significant survival benefits. No significant mortality difference was observed in patients undergoing cardiac surgery (34/410 [8.3%] vs. 47/412 [11%]; RR, 0.82; 95% CI, 0.55-1.22; P = 0.32; I2 = 12%) or those undergoing non-cardiac surgery (9/388 [2.3%] vs. 18/383 [4.7%]; RR, 0.66; 95% CI, 0.31-1.41; P = 0.28; I2 = 0%).

CONCLUSIONS

Administration of non-adrenergic vasopressors was significantly associated with reduced mortality in patients with septic shock. However, no single agent achieved statistical significance in separate analyses. Although the pooled effects of non-adrenergic vasopressors on survival did not reach statistical significance in patients undergoing cardiac or non-cardiac surgery, the confidence intervals included the possibility of both no effect and a clinically important benefit from non-adrenergic agents. These findings justify the conduct of further RCTs comparing non-adrenergic vasopressors to usual care based on noradrenaline alone.

Vasopressor Therapy

Vasopressor therapy represents a key part of intensive care patient management, used to increase and maintain vascular tone and thus adequate tissue perfusion in patients with shock. Norepinephrine is the preferred first-line agent because of its reliable vasoconstrictor effects, with minimal impact on heart rate, and its mild inotropic effects, helping to maintain cardiac output. Whichever vasopressor is used, its effects on blood flow must be considered and excessive vasoconstriction avoided. Other vasoactive agents include vasopressin, which may be considered in vasodilatory states, and angiotensin II, which may be beneficial in patients with high renin levels, although more data are required to confirm this. Dobutamine should be considered, along with continued fluid administration, to help maintain adequate tissue perfusion in patients with reduced oxygen delivery. In this narrative review, we consider the different vasopressor agents, focusing on the importance of tailoring therapy to the individual patient and their hemodynamic response.

Protective hemodynamics: a novel strategy to manage blood pressure

PURPOSE OF REVIEW

This editorial aims to highlight the evolving concept of protective hemodynamics in the management of critically ill patients.

RECENT FINDINGS

Recent literature underscores the limitations of rigid blood pressure targets, particularly in the context of critical care and perioperative management. High blood pressure targets, especially when coupled with high-dose vasopressors, can lead to poor outcomes. 'Protective hemodynamics' aims to maintain cardiovascular stability while reducing risks associated with interventions.

SUMMARY

The implications of adopting protective hemodynamics are profound for both clinical practice and research. Clinically, this approach can reduce iatrogenic harm and improve long-term outcomes for critically ill patients. For research, it opens new avenues for investigating individualized hemodynamic management strategies that prioritize overall patient stability and long-term health over rigid target attainment.

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.

A retrospective cohort analysis comparing the effectiveness and safety of perioperative angiotensin II to adrenergic vasopressors as a first-line vasopressor in kidney transplant recipients

BACKGROUND

Perioperative adrenergic vasopressors in kidney transplantation have been linked to negative outcomes and arrhythmias. Synthetic angiotensin II (AT2S) could improve renal hemodynamics, preserve allograft function, and reduce arrhythmias.

OBJECTIVE

We aimed to compare the effectiveness and safety of AT2S to adrenergic vasopressors when used for perioperative hypotension in kidney transplant.

METHODS

This single-center, retrospective cohort study included adults with perioperative shock requiring AT2S or adrenergic agents as first-line vasopressors during kidney transplant. The primary outcome was the need for a second continuous infusion vasopressor agents beyond the first-line agent. Secondary outcomes assessed adverse events and early allograft outcomes.

RESULTS

Twenty patients receiving AT2S and 60 patients receiving adrenergic vasopressor agents were included. Intraoperatively, 1 of 20 patients (5%) in the AT2S group needed a second continuous vasopressor compared to 7 of 60 patients (11.7%) who needed a second continuous vasopressor in the adrenergic vasopressor group (P = 0.672). Postoperatively, 1 of 20 patients (5%) in the AT2S group compared to 12 of 60 patients (20%) in the adrenergic vasopressor group required a second vasopressor (P = 0.168). There were significantly fewer arrhythmias (1/20 [5%] vs. 17/60 [28.3%]), P = 0.03) and ischemic complications (0/20 [0%] vs. 11/20 [18.3%], P = 0.031) in patients who received AT2S. There were no differences in immediate, slow, or delayed graft function or in discharge, 1-month, and 3-month glomerular filtration rates (p > 0.05). CONCLUSION AND RELEVANCE: Both AT2S and adrenergic vasopressors are effective for perioperative hypotension in kidney transplant, with AT2S showing a lower incidence of arrhythmias and ischemic complications.

Stronger association of intact angiotensinogen with mortality than lactate or renin in critical illness: post-hoc analysis from the VICTAS trial

Sepsis and septic shock remain global healthcare problems associated with high mortality rates despite best therapy efforts. Circulating biomarkers may identify those patients at risk for poor outcomes, however, current biomarkers, most prominently lactate, are non-specific and have an inconsistent impact on prognosis and/or disease management. Activation of the renin-angiotensin- system (RAS) is an early event in sepsis patients and elevated levels of circulating renin are more predictive of worse outcomes than lactate. The precursor protein Angiotensinogen is another key component of the circulating RAS; it is the only known substrate for renin and the ultimate source of the vasopressor Angiotensin II (Ang II). We postulate that lower Angiotensinogen concentrations may reflect a dysfunctional RAS characterized by high renin concentrations but attenuated Ang II generation, which is disproportionate to the high renin response and may compromise adequate support of blood pressure and tissue perfusion in septic patients. The current study compared the association between serum Angiotensinogen with mortality to that of lactate and renin in the VICTAS cohort of sepsis patients at baseline (day 0) by receiver operating characteristic (ROC) and Kaplan-Meier curve analyses. Serum concentration of Angiotensinogen was more strongly associated with 30-day mortality than either the serum concentrations of renin or lactate in sepsis patients. Moreover, the clinical assessment of Angiotensinogen may have distinct advantages over the typical measures of renin. The assessment of intact Angiotensinogen may potentially facilitate more precise therapeutic approaches (including exogenous angiotensin II) to restore a dysfunctional RAS and improve patient outcomes. Additional prospective validation studies are clearly required for this biomarker in the future.

Clinical Response to Third-Line Angiotensin-II vs Epinephrine in Septic Shock: A Propensity-Matched Cohort Study

BACKGROUND

The appropriate third-line vasopressor in septic shock patients receiving norepinephrine and vasopressin is unknown. Angiotensin-II (AT-II) offers a unique mechanism of action to traditionally used vasopressors in septic shock.

OBJECTIVE

The objective of this study was to compare the clinical efficacy and safety of third-line AT-II to epinephrine in patients with septic shock.

METHODS

A single-center, retrospective cohort study of critically ill patients was performed between April 1, 2019 and July 31, 2022. Propensity-matched (2:1) analysis compared adults with septic shock who received third-line AT-II to controls who received epinephrine following norepinephrine and vasopressin. The primary outcome was clinical response 24 hours after third-line vasopressor initiation. Additional efficacy and safety outcomes were investigated.

RESULTS

Twenty-three AT-II patients were compared with 46 epinephrine patients. 47.8% of AT-II patients observed a clinical response at hour 24 compared with 28.3% of epinephrine patients (P = 0.12). In-hospital mortality (65.2% vs 73.9%, P = 0.45), cardiac arrhythmias (26.1% vs 26.1%, P = 0.21), and thromboembolism (4.3% vs 2.2%, P = 0.61) were not observed to be statistically different between groups.

CONCLUSIONS AND RELEVANCE

Administration of AT-II as a third-line vasopressor agent in septic shock patients was not associated with significantly improved clinical response at hour 24 compared with epinephrine. Although underpowered to detect meaningful differences, the clinical observations of this study warrant consideration and further investigation of AT-II as a third-line vasopressor in septic shock.

Complex Pathophysiology of Acute Kidney Injury (AKI) in Aging: Epigenetic Regulation, Matrix Remodeling, and the Healing Effects of H2S

The kidney is an essential excretory organ that works as a filter of toxins and metabolic by-products of the human body and maintains osmotic pressure throughout life. The kidney undergoes several physiological, morphological, and structural changes with age. As life expectancy in humans increases, cell senescence in renal aging is a growing challenge. Identifying age-related kidney disorders and their cause is one of the contemporary public health challenges. While the structural abnormalities to the extracellular matrix (ECM) occur, in part, due to changes in MMPs, EMMPRIN, and Meprin-A, a variety of epigenetic modifiers, such as DNA methylation, histone alterations, changes in small non-coding RNA, and microRNA (miRNA) expressions are proven to play pivotal roles in renal pathology. An aged kidney is vulnerable to acute injury due to ischemia-reperfusion, toxic medications, altered matrix proteins, systemic hemodynamics, etc., non-coding RNA and miRNAs play an important role in renal homeostasis, and alterations of their expressions can be considered as a good marker for AKI. Other epigenetic changes, such as histone modifications and DNA methylation, are also evident in AKI pathophysiology. The endogenous production of gaseous molecule hydrogen sulfide (H2S) was documented in the early 1980s, but its ameliorative effects, especially on kidney injury, still need further research to understand its molecular mode of action in detail. H2S donors heal fibrotic kidney tissues, attenuate oxidative stress, apoptosis, inflammation, and GFR, and also modulate the renin-angiotensin-aldosterone system (RAAS). In this review, we discuss the complex pathophysiological interplay in AKI and its available treatments along with future perspectives. The basic role of H2S in the kidney has been summarized, and recent references and knowledge gaps are also addressed. Finally, the healing effects of H2S in AKI are described with special emphasis on epigenetic regulation and matrix remodeling.

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.

Blood Pressure Management for Hypotensive Patients in Intensive Care and Perioperative Cardiovascular Settings

Blood pressure is a critical physiological parameter, particularly in the context of cardiac intensive care and perioperative settings. As a primary indicator of organ perfusion, the maintenance of adequate blood pressure is imperative for the assurance of sufficient tissue oxygen delivery. Among critically ill and major surgery patients, the continuous monitoring of blood pressure is performed as a standard practice for patients. Nonetheless, uncertainties remain regarding blood pressure goals, and there is no consensus regarding blood pressure targets. This review describes the determinants of blood pressure, examine the influence of blood pressure on organ perfusion, and synthesize the current clinical evidence from various intensive care and perioperative settings to provide a concise guidance for daily clinical practice.

Transitions and Long-Term Clinical Outcomes in Patients Admitted in Intensive Care Units Receiving Continuous Renal Replacement Therapy

Introduction: Acute kidney injury (AKI) significantly disrupts vital renal functions and is a common and serious condition in intensive care units (ICUs). AKI leads to extended hospital stays, increases mortality rates, and often necessitates nephrology consultations. Continuous renal replacement therapy (CRRT) plays a central role in managing AKI, requiring a multidisciplinary approach involving nephrologists, intensivists, and anesthesiologists. This study examines the clinical profile and progression of AKI in ICU patients requiring CRRT, with a focus on CRRT indications and modalities. Materials and Methods: We conducted a single-center retrospective observational study on ICU patients with AKI requiring CRRT from January to December 2019. AKI diagnosis followed the RIFLE criteria, and patients who received CRRT for less than 36 h were excluded. Data collected included demographics, hemodynamic parameters, and renal function parameters, with follow-ups at 1 week, 1 month, 6 months, and 12 months. Statistical analyses evaluated outcomes and transitions between CRRT and other renal replacement therapies. Results: Among 123 evaluated patients, 95 met inclusion criteria. Fifteen patients received CRRT for less than 36 h, with an early mortality rate of 80%. The final cohort comprised 80 patients who underwent CRRT for over 36 h, with a mean age of 65.3 years (SD = 13.6) and a Charlson index of 6.4. Patients were categorized based on primary diagnosis into heart failure, cardiac surgery, sepsis, other surgeries, and miscellanea groups. Mortality rates were highest in the heart failure and miscellanea groups. Significant variability was observed in therapy transitions and long-term outcomes. Continuous venovenous hemodiafiltration (CVVHDF) was the most frequently used CRRT modality. Conclusions: This study highlights the variability in CRRT practices and the poor prognosis for critically ill patients with AKI requiring CRRT. Timely nephrology consultation and tailored treatment plans may improve patient outcomes and optimize CRRT utilization. Future research should focus on refining CRRT protocols and exploring preventive strategies for AKI.

The use of angiotensin II for the management of distributive shock: expert consensus statements

BACKGROUND

Despite the growing body of evidence supporting the use of angiotensin II (ATII) in distributive shock, its integration into existing treatment algorithms requires careful consideration of factors related to patient comorbidities, hemodynamic parameters, cost-effectiveness, and risk-benefit balance. Moreover, several questions regarding its use in clinical practice warrant further investigations. To address these challenges, a group of Italian intensive care specialists (the panel) developed a consensus process using a modified Delphi technique.

METHODS

The panel defined five clinical questions during an online scoping workshop and then provided a short list of statements related to each clinical question based on literature review and clinical experience. A total of 20 statements were collected. Two coordinators screened and selected the final list of statements to be included in the online survey, which consisted of 17 statements. The consensus was reached when ≥ 75% of respondents assigned a score within the 3-point range of 1-3 (disagreement) or 7-9 (agreement).

RESULTS

Overall, a consensus on agreement was reached on 13 statements defining the existing gaps in scientific evidence, the possibility of evaluating the addition of drugs with different mechanisms of action for the treatment of refractory shock, the utility of ATII in reducing the catecholamine requirements in the treatment of vasopressor-resistant septic shock, and the effectiveness of ATII in treating patients in whom angiotensin-converting enzyme activity is reduced or pharmacologically blocked. It was widely shared that renin concentration can be used to identify patients who most likely benefit from ATII to restore vascular tone. Thus, the patients who might benefit most from using ATII were defined. Lastly, some potential barriers to the use of ATII were described.

CONCLUSIONS

ATII was recognized as a useful treatment to reduce catecholamine requirements in treating vasopressor-resistant septic shock. At the same time, the need for additional clinical trials to further elucidate the efficacy and safety of ATII, as well as investigations into potential mechanisms of action and optimization of treatment protocols in patients with refractory distributive shock, emerged.

Current perspectives in the management of sepsis and septic shock

Within patients with sepsis, there exists significant heterogeneity, and while all patients should receive conventional therapy, there are subgroups of patients who may benefit from specific therapies, often referred to as rescue therapies. Therefore, the identification of these specific patient subgroups is crucial and lays the groundwork for the application of precision medicine based on the development of targeted interventions. Over the years, efforts have been made to categorize sepsis into different subtypes based on clinical characteristics, biomarkers, or underlying mechanisms. For example, sepsis can be stratified into different phenotypes based on the predominant dysregulated host response. These phenotypes can range from hyperinflammatory states to immunosuppressive states and even mixed phenotypes. Each phenotype may require different therapeutic approaches to improve patient outcomes. Rescue strategies for septic shock may encompass various interventions, such as immunomodulatory therapies, extracorporeal support (e.g., ECMO), or therapies targeted at specific molecular or cellular pathways involved in the pathophysiology of sepsis. In recent years, there has been growing interest in precision medicine approaches to sepsis and phenotype identification. Precision medicine aims to tailor treatments to each individual patient based on their unique characteristics and disease mechanisms.

Angiotensin II as a Vasopressor for Perioperative Hypotension in Solid Organ Transplant

During the perioperative period of transplantation, patients experience hypotension secondary to the side effects of anesthesia, surgical stress, inflammatory triggering, and intraoperative fluid shifts, among others causes. Vasopressor support, in this context, must reverse systemic hypotension, but ideally, the agents used should benefit allograft function and avoid the adverse events commonly seen after transplantation. Traditional therapies to reverse hypotension include catecholamine vasopressors (norepinephrine, epinephrine, dopamine, and phenylephrine), but their utility is limited when considering allograft complications and adverse events such as arrhythmias with agents with beta-adrenergic properties. Synthetic angiotensin II (AT2S-[Giapreza]) is a novel vasopressor indicated for distributive shock with a unique mechanism of action as an angiotensin receptor agonist restoring balance to an often-disrupted renin angiotensin aldosterone system. Additionally, AT2S provides a balanced afferent and efferent arteriole vasoconstriction at the level of the kidney and could avoid the arrhythmic complications of a beta-adrenergic agonist. While the data, to date, are limited, AT2S has demonstrated safety in case reports, pilot studies, and small series in the kidney, liver, heart, and lung transplant populations. There are physiologic and hemodynamic reasons why AT2S could be a more utilized agent in these populations, but further investigation is warranted.

A Pilot Study of Renin-Guided Angiotensin-II Infusion to Reduce Kidney Stress After Cardiac Surgery

BACKGROUND

Vasoplegia is common after cardiac surgery, is associated with hyperreninemia, and can lead to acute kidney stress. We aimed to conduct a pilot study to test the hypothesis that, in vasoplegic cardiac surgery patients, angiotensin-II (AT-II) may not increase kidney stress (measured by [TIMP-2]*[IGFBP7]).

METHODS

We randomly assigned patients with vasoplegia (cardiac index [CI] > 2.1l/min, postoperative hypotension requiring vasopressors) and Δ-renin (4-hour postoperative-preoperative value) ≥3.7 µU/mL, to AT-II or placebo targeting a mean arterial pressure ≥65 mm Hg for 12 hours. The primary end point was the incidence of kidney stress defined as the difference between baseline and 12 hours [TIMP-2]*[IGFBP7] levels. Secondary end points included serious adverse events (SAEs).

RESULTS

We randomized 64 patients. With 1 being excluded, 31 patients received AT-II, and 32 received placebo. No significant difference was observed between AT-II and placebo groups for kidney stress (Δ-[TIMP-2]*[IGFBP7] 0.06 [ng/mL] 2 /1000 [Q1-Q3, -0.24 to 0.28] vs -0.08 [ng/mL] 2 /1000 [Q1-Q3, -0.35 to 0.14]; P = .19; Hodges-Lehmann estimation of the location shift of 0.12 [ng/mL] 2 /1000 [95% confidence interval, CI, -0.1 to 0.36]). AT-II patients received less fluid during treatment than placebo patients (2946 vs 3341 mL, P = .03), and required lower doses of norepinephrine equivalent (0.19 mg vs 4.18mg, P < .001). SAEs were reported in 38.7% of patients in the AT-II group and in 46.9% of patients in the placebo group.

CONCLUSIONS

The infusion of AT-II for 12 hours appears feasible and did not lead to an increase in kidney stress in a high-risk cohort of cardiac surgery patients. These findings support the cautious continued investigation of AT-II as a vasopressor in hyperreninemic cardiac surgery patients.

Bidirectional pressure: a mini review of ventilator-lung-kidney interactions

Acute kidney injury and respiratory failure that requires mechanical ventilation are both common complications of critical illnesses. Failure of either of these organ systems also increases the risk of failure to the other. As a result, there is a high incidence of patients with concomitant acute kidney injury and the need for mechanical ventilation, which has a devasting impact on intensive care unit outcomes, including mortality. Despite decades of research into the mechanisms of ventilator-lung-kidney interactions, several gaps in knowledge remain and current treatment strategies are primarily supportive. In this review, we outline our current understanding of the mechanisms of acute kidney injury due to mechanical ventilation including a discussion of; 1) The impact of mechanical ventilation on renal perfusion, 2) activation of neurohormonal pathways by positive pressure ventilation, and 3) the role of inflammatory mediators released during ventilator induced lung injury. We also provide a review of the mechanisms by which acute kidney injury increases the risk of respiratory failure. Next, we outline a summary of the current therapeutic approach to preventing lung and kidney injury in the critically ill, including fluid and vasopressor management, ventilator strategies, and treatment of acute kidney injury. Finally, we conclude with a discussion outlining opportunities for novel investigations that may provide a rationale for new treatment approaches.

Impaired angiotensin II signaling in septic shock

Recent years have seen a resurgence of interest for the renin-angiotensin-aldosterone system in critically ill patients. Emerging data suggest that this vital homeostatic system, which plays a crucial role in maintaining systemic and renal hemodynamics during stressful conditions, is altered in septic shock, ultimately leading to impaired angiotensin II-angiotensin II type 1 receptor signaling. Indeed, available evidence from both experimental models and human studies indicates that alterations in the renin-angiotensin-aldosterone system during septic shock can occur at three distinct levels: 1. Impaired generation of angiotensin II, possibly attributable to defects in angiotensin-converting enzyme activity; 2. Enhanced degradation of angiotensin II by peptidases; and/or 3. Unavailability of angiotensin II type 1 receptor due to internalization or reduced synthesis. These alterations can occur either independently or in combination, ultimately leading to an uncoupling between the renin-angiotensin-aldosterone system input and downstream angiotensin II type 1 receptor signaling. It remains unclear whether exogenous angiotensin II infusion can adequately address all these mechanisms, and additional interventions may be required. These observations open a new avenue of research and offer the potential for novel therapeutic strategies to improve patient prognosis. In the near future, a deeper understanding of renin-angiotensin-aldosterone system alterations in septic shock should help to decipher patients' phenotypes and to implement targeted interventions.

The REPERFUSE study protocol: The effects of vasopressor therapy on renal perfusion in patients with septic shock-A mechanistically focused randomised control trial

INTRODUCTION

Acute kidney injury (AKI) is a common complication of septic shock and together these conditions carry a high mortality risk. In septic patients who develop severe AKI, renal cortical perfusion is deficient despite normal macrovascular organ blood flow. This intra-renal perfusion abnormality may be amenable to pharmacological manipulation, which may offer mechanistic insight into the pathophysiology of septic AKI. The aim of the current study is to investigate the effects of vasopressin and angiotensin II on renal microcirculatory perfusion in a cohort of patients with septic shock.

METHODS AND ANALYSIS

In this single centre, mechanistically focussed, randomised controlled study, 45 patients with septic shock will be randomly allocated to either of the study vasopressors (vasopressin or angiotensin II) or standard therapy (norepinephrine). Infusions will be titrated to maintain a mean arterial pressure (MAP) target set by the attending clinician. Renal microcirculatory assessment will be performed for the cortex and medulla using contrast-enhanced ultrasound (CEUS) and urinary oxygen tension (pO2), respectively. Renal macrovascular flow will be assessed via renal artery ultrasound. Measurement of systemic macrovascular flow will be performed through transthoracic echocardiography (TTE) and microvascular flow via sublingual incident dark field (IDF) video microscopy. Measures will be taken at baseline, +1 and +24hrs following infusion of the study drug commencing. Blood and urine samples will also be collected at the measurement time points. Longitudinal data will be compared between groups and over time.

DISCUSSION

Vasopressors are integral to the management of patients with septic shock. This study aims to further understanding of the relationship between this therapy, renal perfusion and the development of AKI. In addition, using CEUS and urinary pO2, we hope to build a more complete picture of renal perfusion in septic shock by interrogation of the constituent parts of the kidney. Results will be published in peer-reviewed journals and presented at academic meetings.

TRIAL REGISTRATION

The REPERFUSE study was registered on Clinical Trials.gov (NCT06234592) on the 30th Jan 24.

Proposal for the use of angiotensin II in distributive shock after extracorporeal circulation - position paper of the Section of Intensive Care Medicine and the Section of Cardiothoracic Anaesthesiology of the Polish Society of Anaesthesiology and Intensive Therapy

Angiotensin II (AT) is a potent vasoconstrictor and hypertensive drug that is registered for the treatment of severe hypotension in vasoplegic shock. Growing experience with the use of AT in cardiac surgery allows the first therapeutic algorithms to be created. This paper is a proposal for the use of AT in distributive shock after extracorporeal circulation.

Dysfunction of the renin-angiotensin-aldosterone system in human septic shock

Sepsis and septic shock are global healthcare problems associated with mortality rates of up to 40% despite optimal standard-of-care therapy and constitute the primary cause of death in intensive care units worldwide. Circulating biomarkers of septic shock severity may represent a clinically relevant approach to individualize those patients at risk for worse outcomes early in the course of the disease, which may facilitate early and more precise interventions to improve the clinical course. However, currently used septic shock biomarkers, including lactate, may be non-specific and have variable impact on prognosis and/or disease management. Activation of the renin-angiotensin-aldosterone system (RAAS) is likely an early event in septic shock, and studies suggest that an elevated level of renin, the early and committed step in the RAAS cascade, is a better predictor of worse outcomes in septic shock, including mortality, than the current standard-of-care measure of lactate. Despite a robust increase in renin, other elements of the RAAS, including endogenous levels of Ang II, may fail to sufficiently increase to maintain blood pressure, tissue perfusion, and protective immune responses in septic shock patients. We review the current clinical literature regarding the dysfunction of the RAAS in septic shock and potential therapeutic approaches to improve clinical outcomes.

Acute Kidney Injury in Sepsis

Sepsis-associated kidney injury is common in critically ill patients and significantly increases morbidity and mortality rates. Several complex pathophysiological factors contribute to its presentation and perpetuation, including macrocirculatory and microcirculatory changes, mitochondrial dysfunction, and metabolic reprogramming. Recovery from acute kidney injury (AKI) relies on the evolution towards adaptive mechanisms such as endothelial repair and tubular cell regeneration, while maladaptive repair increases the risk of progression to chronic kidney disease. Fundamental management strategies include early sepsis recognition and prompt treatment, through the administration of adequate antimicrobial agents, fluid resuscitation, and vasoactive agents as needed. In septic patients, organ-specific support is often required, particularly renal replacement therapy (RRT) in the setting of severe AKI, although ongoing debates persist regarding the ideal timing of initiation and dosing of RRT. A comprehensive approach integrating early recognition, targeted interventions, and close monitoring is essential to mitigate the burden of SA-AKI and improve patient outcomes in critical care settings.

Predictors and Impact of Prolonged Vasoplegia After Continuous-Flow Left Ventricular Assist Device Implantation

Background

Vasoplegia after cardiac surgery is associated with adverse outcomes. However, the clinical effects of vasoplegia and the significance of its duration after continuous-flow left ventricular assist device (CF-LVAD) implantation are less known.

Objectives

This study aimed to identify predictors of and outcomes from transient vs prolonged vasoplegia after CF-LVAD implantation.

Methods

The study was a retrospective review of consecutive patients who underwent CF-LVAD implantation between January 1, 2005, and December 31, 2017. Vasoplegia was defined as the presence of all of the following: mean arterial pressure ≤65 mm Hg, vasopressor (epinephrine, norepinephrine, vasopressin, or dopamine) use for >6 hours within the first 24 hours postoperatively, cardiac index ≥2.2 L/min/m2 and systemic vascular resistance <800 dyne/s/cm5, and vasodilatory shock not attributable to other causes. Prolonged vasoplegia was defined as that lasting 12 to 24 hours; transient vasoplegia was that lasting 6 to <12 hours. Patient characteristics, outcomes, and risk factors were analyzed.

Results

Of the 600 patients who underwent CF-LVAD implantation during the study period, 182 (30.3%) developed vasoplegia. Mean patient age was similar between the vasoplegia and no-vasoplegia groups. Prolonged vasoplegia (n = 78; 13.0%), compared with transient vasoplegia (n = 104; 17.3%), was associated with greater 30-day mortality (16.7% vs 5.8%; P = 0.02). Risk factors for prolonged vasoplegia included preoperative dialysis and elevated body mass index.

Conclusions

Compared with vasoplegia overall, prolonged vasoplegia was associated with worse survival after CF-LVAD implantation. Treatment to avoid or minimize progression to prolonged vasoplegia may be warranted.

Treatment of Acute Kidney Injury: A Review of Current Approaches and Emerging Innovations

Acute kidney injury (AKI) is a complex and life-threatening condition with multifactorial etiologies, ranging from ischemic injury to nephrotoxic exposures. Management is founded on treating the underlying cause of AKI, but supportive care-via fluid management, vasopressor therapy, kidney replacement therapy (KRT), and more-is also crucial. Blood pressure targets are often higher in AKI, and these can be achieved with fluids and vasopressors, some of which may be more kidney-protective than others. Initiation of KRT is controversial, and studies have not consistently demonstrated any benefit to early start dialysis. There are no targeted pharmacotherapies for AKI itself, but some do exist for complications of AKI; additionally, medications become a key aspect of AKI management because changes in renal function and dialysis support can lead to issues with both toxicities and underdosing. This review will cover existing literature on these and other aspects of AKI treatment. Additionally, this review aims to identify gaps and challenges and to offer recommendations for future research and clinical practice.

ACE inhibitors and angiotensin receptor blockers differentially alter the response to angiotensin II treatment in vasodilatory shock

BACKGROUND

Angiotensin-converting enzyme inhibitor (ACEi) and angiotensin receptor blockers (ARB) medications are widely prescribed. We sought to assess how pre-admission use of these medications might impact the response to angiotensin-II treatment during vasodilatory shock.

METHODS

In a post-hoc subgroup analysis of the randomized, placebo-controlled, Angiotensin Therapy for High Output Shock (ATHOS-3) trial, we compared patients with chronic angiotensin-converting enzyme inhibitor (ACEi) use, and patients with angiotensin receptor blocker (ARB) use, to patients without exposure to either ACEi or ARB. The primary outcome was mean arterial pressure after 1-h of treatment. Additional clinical outcomes included mean arterial pressure and norepinephrine equivalent dose requirements over time, and study-drug dose over time. Biological outcomes included baseline RAS biomarkers (renin, angiotensin-I, angiotensin-II, and angiotensin-I/angiotensin-II ratio), and the change in renin from 0 to 3 h.

RESULTS

We included n = 321 patients, of whom, 270 were ACEi and ARB-unexposed, 29 were ACEi-exposed and 22 ARB-exposed. In ACEi/ARB-unexposed patients, angiotensin-treated patients, compared to placebo, had higher hour-1 mean arterial pressure (9.1 mmHg [95% CI 7.6-10.1], p < 0.0001), lower norepinephrine equivalent dose over 48-h (p = 0.0037), and lower study-drug dose over 48-h (p < 0.0001). ACEi-exposed patients treated with angiotensin-II showed similarly higher hour-1 mean arterial pressure compared to ACEi/ARB-unexposed (difference in treatment-effect: - 2.2 mmHg [95% CI - 7.0-2.6], pinteraction = 0.38), but a greater reduction in norepinephrine equivalent dose (pinteraction = 0.0031) and study-drug dose (pinteraction < 0.0001) over 48-h. In contrast, ARB-exposed patients showed an attenuated effect of angiotensin-II on hour-1 mean arterial pressure versus ACEi/ARB-unexposed (difference in treatment-effect: - 6.0 mmHg [95% CI - 11.5 to - 0.6], pinteraction = 0.0299), norepinephrine equivalent dose (pinteraction < 0.0001), and study-drug dose (pinteraction = 0.0008). Baseline renin levels and angiotensin-I/angiotensin-II ratios were highest in ACEi-exposed patients. Finally, angiotensin-II treatment reduced hour-3 renin in ACEi/ARB-unexposed and ACEi-exposed patients but not in ARB-exposed patients.

CONCLUSIONS

In vasodilatory shock patients, the cardiovascular and biological RAS response to angiotensin-II differed based upon prior exposure to ACEi and ARB medications. ACEi-exposure was associated with increased angiotensin II responsiveness, whereas ARB-exposure was associated with decreased responsiveness. These findings have clinical implications for patient selection and dosage of angiotensin II in vasodilatory shock. Trial Registration ClinicalTrials.Gov Identifier: NCT02338843 (Registered January 14th 2015).

Characterizing the Stability of Angiotensin II in 0.9% Sodium Chloride Using High Performance Liquid Chromatography and Liquid Chromatography Tandem Mass Spectrometry

Purpose: The purpose of this study was to evaluate the stability of angiotensin II in 0.9% sodium chloride for up to 5 days. Methods: We prepared angiotensin II dilutions, by aseptically diluting 2.5 mg (1 mL) in 249 mL 0.9% sodium chloride creating a solution of 10 000 ng/mL. Admixtures were stored under refrigeration (5 ± 3°C). Stability of the dilution was assessed by: preservation of clarity, consistency of pH, and retention of concentration. Solutions were sampled at times 0, 24, 48, 72, 96, 120 hours. Solutions were analyzed via High-Performance Liquid Chromatography (HPLC-UV) and Liquid Chromatography Mass Spectrometry (LC-MS/MS). Retention of concentration was set a priori at > 90% of initial concentration. Results: Clarity, color, and pH at all sample time points remained constant. Both methods of analysis confirmed similar results. When stored under refrigeration, the concentration of angiotensin II solution remained above 90% of initial concentration throughout the entire sampling period. Conclusions: Angiotensin II in 0.9% sodium chloride stored in infusion bags under refrigeration (5 ± 3°C) maintained at least 90% of their original concentrations for up to 5 days. Stability was also demonstrated based on turbidity, color, and pH assessment.

Sepsis-associated acute kidney injury: recent advances in enrichment strategies, sub-phenotyping and clinical trials

Acute kidney injury (AKI) often complicates sepsis and is associated with high morbidity and mortality. In recent years, several important clinical trials have improved our understanding of sepsis-associated AKI (SA-AKI) and impacted clinical care. Advances in sub-phenotyping of sepsis and AKI and clinical trial design offer unprecedented opportunities to fill gaps in knowledge and generate better evidence for improving the outcome of critically ill patients with SA-AKI. In this manuscript, we review the recent literature of clinical trials in sepsis with focus on studies that explore SA-AKI as a primary or secondary outcome. We discuss lessons learned and potential opportunities to improve the design of clinical trials and generate actionable evidence in future research. We specifically discuss the role of enrichment strategies to target populations that are most likely to derive benefit and the importance of patient-centered clinical trial endpoints and appropriate trial designs with the aim to provide guidance in designing future trials.

The scientific rationale and study protocol for the DPP3, Angiotensin II, and Renin Kinetics in Sepsis (DARK-Sepsis) randomized controlled trial: serum biomarkers to predict response to angiotensin II versus standard-of-care vasopressor therapy in the treatment of septic shock

BACKGROUND

Data to support the use of specific vasopressors in septic shock are limited. Since angiotensin II (AT2) was approved by the Food and Drug Administration in 2017, multiple mechanistically distinct vasopressors are available to treat septic shock, but minimal data exist regarding which patients are most likely to benefit from each agent. Renin and dipeptidyl peptidase 3 (DPP3) are components of the renin-angiotensin-aldosterone system which have been shown to outperform lactate in predicting sepsis prognosis, and preliminary data suggest they could prove useful as biomarkers to guide AT2 use in septic shock.

METHODS

The DARK-Sepsis trial is an investigator-initiated industry-funded, open-label, single-center randomized controlled trial of the use of AT2 versus standard of care (SOC) vasopressor therapy in patients admitted to the intensive care unit (ICU) with vasodilatory shock requiring norepinephrine ≥ 0.1 mcg/kg/min. In both groups, a series of renin and DPP3 levels will be obtained over the first 24 h of treatment with AT2 or SOC. The primary study outcome will be the ability of these biomarkers to predict response to vasopressor therapy, as measured by change in total norepinephrine equivalent dose of vasopressors at 3 h post-drug initiation or the equivalent timepoint in the SOC arm. To determine if the ability to predict vasopressor response is specific to AT2 therapy, the primary analysis will be the ability of baseline renin and DPP3 levels to predict vasopressor response adjusted for treatment arm (AT2 versus control) and Sequential Organ Failure Assessment (SOFA) scores. Secondary outcomes will include rates of acute kidney injury, need for mechanical ventilation and kidney replacement therapy, lengths of stay in the ICU and hospital, ICU and hospital mortality, and rates of prespecified adverse events.

DISCUSSION

With an armamentarium of mechanistically distinct vasopressor agents now available, sub-phenotyping patients using biomarkers has the potential to improve septic shock outcomes by enabling treatment of the correct patient with the correct vasopressor at the correct time. However, this approach requires validation in a large definitive multicenter trial. The data generated through the DARK-Sepsis study will prove crucial to the optimal design and patient enrichment of such a pivotal trial.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05824767. Registered on April 24, 2023.

Ceria-Based Therapeutic Antioxidants for Biomedical Applications

The growing interest in nanomedicine over the last 20 years has carved out a research field called "nanocatalytic therapy," where catalytic reactions mediated by nanomaterials are employed to intervene in disease-critical biomolecular processes. Among many kinds of catalytic/enzyme-mimetic nanomaterials investigated thus far, ceria nanoparticles stand out from others owing to their unique scavenging properties against biologically noxious free radicals, including reactive oxygen species (ROS) and reactive nitrogen species (RNS), by exerting enzyme mimicry and nonenzymatic activities. Much effort has been made to utilize ceria nanoparticles as self-regenerating antioxidative and anti-inflammatory agents for various kinds of diseases, given the detrimental effects of ROS and RNS therein that need alleviation. In this context, this review is intended to provide an overview as to what makes ceria nanoparticles merit attention in disease therapy. The introductory part describes the characteristics of ceria nanoparticles as an oxygen-deficient metal oxide. The pathophysiological roles of ROS and RNS are then presented, as well as their scavenging mechanisms by ceria nanoparticles. Representative examples of recent ceria-nanoparticle-based therapeutics are summarized by categorization into organ and disease types, followed by the discussion on the remaining challenges and future research directions.

Angiotensin ii therapy in refractory septic shock: which patient can benefit most? A narrative review

Patients with septic shock who experience refractory hypotension despite adequate fluid resuscitation and high-dose noradrenaline have high mortality rates. To improve outcomes, evidence-based guidelines recommend starting a second vasopressor, such as vasopressin, if noradrenaline doses exceed 0.5 µg/kg/min. Recently, promising results have been observed in treating refractory hypotension with angiotensin II, which has been shown to increase mean arterial pressure and has been associated with improved outcomes. This narrative review aims to provide an overview of the pathophysiology of the renin-angiotensin system and the role of endogenous angiotensin II in vasodilatory shock with a focus on how angiotensin II treatment impacts clinical outcomes and on identifying the population that may benefit most from its use.

Exploring post-SEPSIS and post-COVID-19 syndromes: crossovers from pathophysiology to therapeutic approach

Sepsis, driven by several infections, including COVID-19, can lead to post-sepsis syndrome (PSS) and post-acute sequelae of COVID-19 (PASC). Both these conditions share clinical and pathophysiological similarities, as survivors face persistent multi-organ dysfunctions, including respiratory, cardiovascular, renal, and neurological issues. Moreover, dysregulated immune responses, immunosuppression, and hyperinflammation contribute to these conditions. The lack of clear definitions and diagnostic criteria hampers comprehensive treatment strategies, and a unified therapeutic approach is significantly needed. One potential target might be the renin-angiotensin system (RAS), which plays a significant role in immune modulation. In fact, RAS imbalance can exacerbate these responses. Potential interventions involving RAS include ACE inhibitors, ACE receptor blockers, and recombinant human ACE2 (rhACE2). To address the complexities of PSS and PASC, a multifaceted approach is required, considering shared immunological mechanisms and the role of RAS. Standardization, research funding, and clinical trials are essential for advancing treatment strategies for these conditions.

Proteomics-based screening of AKR1B1 as a therapeutic target and validation study for sepsis-associated acute kidney injury

Background

Sepsis and sepsis-associated acute kidney injury (SA-AKI) pose significant global health challenges, necessitating the development of innovative therapeutic strategies. Dysregulated protein expression has been implicated in the initiation and progression of sepsis and SA-AKI. Identifying potential protein targets and modulating their expression is crucial for exploring alternative therapies.

Method

We established an SA-AKI rat model using cecum ligation perforation (CLP) and employed differential proteomic techniques to identify protein expression variations in kidney tissues. Aldose reductase (AKR1B1) emerged as a promising target. The SA-AKI rat model received treatment with the aldose reductase inhibitor (ARI), epalrestat. Blood urea nitrogen (BUN) and creatinine (CRE) levels, as well as IL-1β, IL-6 and TNF-α levels in the serum and kidney tissues, were monitored. Hematoxylin-eosin (H-E) staining and a pathological damage scoring scale assessed renal tissue damage, while protein blotting determined PKC (protein kinase C)/NF-κB pathway protein expression.

Result

Differential proteomics revealed significant downregulation of seven proteins and upregulation of 17 proteins in the SA-AKI rat model renal tissues. AKR1B1 protein expression was notably elevated, confirmed by Western blot. ARI prophylactic administration and ARI treatment groups exhibited reduced renal injury, low BUN and CRE levels and decreased IL-1β, IL-6 and TNF-α levels compared to the CLP group. These changes were statistically significant (P < 0.05). AKR1B1, PKC-α, and NF-κB protein expression levels were also lowered in the ARI prophylactic administration and ARI treatment groups compared to the CLP group (P < 0.05).

Conclusions

Epalrestat appeared to inhibit the PKC/NF-κB inflammatory pathway by inhibiting AKR1B1, resulting in reduced inflammatory cytokine levels in renal tissues and blood. This mitigated renal tissue injuries and improved the systemic inflammatory response in the severe sepsis rat model. Consequently, AKR1B1 holds promise as a target for treating sepsis-associated acute kidney injuries.

Sepsis-associated acute kidney injury-treatment standard

Sepsis is a host's deleterious response to infection, which could lead to life-threatening organ dysfunction. Sepsis-associated acute kidney injury (SA-AKI) is the most frequent organ dysfunction and is associated with increased morbidity and mortality. Sepsis contributes to ≈50% of all AKI in critically ill adult patients. A growing body of evidence has unveiled key aspects of the clinical risk factors, pathobiology, response to treatment and elements of renal recovery that have advanced our ability to detect, prevent and treat SA-AKI. Despite these advancements, SA-AKI remains a critical clinical condition and a major health burden, and further studies are needed to diminish the short and long-term consequences of SA-AKI. We review the current treatment standards and discuss novel developments in the pathophysiology, diagnosis, outcome prediction and management of SA-AKI.

Angiotensin II for the Treatment of Refractory Shock: A Matched Analysis

OBJECTIVES

To determine if angiotensin II is associated with improved outcomes as measured by 30- and 90-day mortality as well as other secondary outcomes such as organ dysfunction and adverse events.

DESIGN

Retrospective, matched analysis of patients receiving angiotensin II compared with both historical and concurrent controls receiving equivalent doses of nonangiotensin II vasopressors.

SETTING

Multiple ICUs in a large, university-based hospital.

PATIENTS

Eight hundred thirteen adult patients with shock admitted to an ICU and requiring vasopressor support.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Angiotensin II use had no association with the primary outcome of 30-day mortality (60% vs 56%; p = 0.292). The secondary outcome of 90-day mortality was also similar (65% vs 63%; p = 0.440) as were changes in Sequential Organ Failure Assessment scores over a 5-day monitoring period after enrollment. Angiotensin II was not associated with increased rates of kidney replacement therapy (odds ratio [OR], 1.39; 95% CI, 0.88-2.19; p = 0.158) or receipt of mechanical ventilation (OR, 1.50; 95% CI, 0.41-5.51; p = 0.539) after enrollment, and the rate of thrombotic events was similar between angiotensin II and control patients (OR, 1.02; 95% CI, 0.71-1.48; p = 0.912).

CONCLUSIONS

In patients with severe shock, angiotensin II was not associated with improved mortality or organ dysfunction and was not associated with an increased rate of adverse events.

Micro-lightguide spectrophotometry assessment of hepatic and intestinal microcirculation in endotoxemic rats during intravenous treatment with angiotensin II

INTRODUCTION

During septic shock, impairment of microcirculation leads to enhanced permeability of intestinal mucosa triggered by generalized vasodilation and capillary leak. Intravenous angiotensin II (AT-II) has been approved for the treatment of septic shock; however, no in-vivo data exist on the influence of AT-II on hepatic and intestinal microcirculation.

MATERIAL AND METHODS

Sixty male Lewis rats were randomly assigned to six study groups (each n = 10): sham, lipopolysaccharide-induced septic shock, therapy with low- or high-dose AT-II (50 or 100 ng/kg/min, respectively), and septic shock treated with low- or high-dose AT-II. After median laparotomy, hepatic and intestinal microcirculation measures derived from micro-lightguide spectrophotometry were assessed for 3 h and included oxygen saturation (SO2), relative blood flow (relBF) and relative hemoglobin level (relHb). Hemodynamic measurements were performed using a left ventricular conductance catheter, and blood samples were taken hourly to analyze blood gasses and systemic cytokines.

RESULTS

AT-II increased mean arterial pressure in a dose-dependent manner in both septic and non-septic animals (p < 0.001). Lower hepatic and intestinal SO2 (both p < 0.001) were measured in animals without endotoxemia who received high-dose AT-II treatment, however, significantly impaired cardiac output was also reported in this group (p < 0.001). In endotoxemic rats, hepatic relBF and relHb were comparable among the treatment groups; however, hepatic SO2 was reduced during low- and high-dose AT-II treatment (p < 0.001). In contrast, intestinal SO2 remained unchanged despite treatment with AT-II. Intestinal relBF (p = 0.028) and interleukin (IL)-10 plasma levels (p < 0.001) were significantly elevated during treatment with high-dose AT-II compared with low-dose AT-II.

CONCLUSIONS

A dose-dependent decrease of hepatic and intestinal microcirculation during therapy with AT-II in non-septic rats was observed, which might have been influenced by a corresponding reduction in cardiac output due to elevated afterload. While hepatic microcirculation was reduced during endotoxemia, no evidence for a reduction in intestinal microcirculation facilitated by AT-II was found. In contrast, both intestinal relBF and anti-inflammatory IL-10 levels were increased during high-dose AT-II treatment.

The role of renin-angiotensin system in sepsis-associated acute kidney injury: mechanisms and therapeutic implications

PURPOSE OF REVIEW

This review aims to explore the relationship between the renin angiotensin system (RAS) and sepsis-associated acute kidney injury (SA-AKI), a common complication in critically ill patients associated with mortality, morbidity, and long-term cardiovascular complications. Additionally, this review aims to identify potential therapeutic approaches to intervene with the RAS and prevent the development of AKI.

RECENT FINDINGS

Recent studies have provided increasing evidence of RAS alteration during sepsis, with systemic and local RAS disturbance, which can contribute to SA-AKI. Angiotensin II was recently approved for catecholamine resistant vasodilatory shock and has been associated with improved outcomes in selected patients.

SUMMARY

SA-AKI is a common condition that can involve disturbances in the RAS, particularly the canonical angiotensin-converting enzyme (ACE) angiotensin-II (Ang II)/angiotensin II receptor 1 (AT-1R) axis. Increased renin levels, a key enzyme in the RAS, have been shown to be associated with AKI and may also guide vasopressor therapy in shock. In patients with high renin levels, angiotensin II administration may reduce renin concentration, improve intra-renal hemodynamics, and enhance signaling through the angiotensin II receptor 1. Further studies are needed to explore the role of the RAS in SA-AKI and the potential for targeted therapies.

The alternative renin-angiotensin system in critically ill patients: pathophysiology and therapeutic implications

The renin-angiotensin system (RAS) plays a crucial role in regulating blood pressure and the cardio-renal system. The classical RAS, mainly mediated by angiotensin I, angiotensin-converting enzyme, and angiotensin II, has been reported to be altered in critically ill patients, such as those in vasodilatory shock. However, recent research has highlighted the role of some components of the counterregulatory axis of the classical RAS, termed the alternative RAS, such as angiotensin-converting Enzyme 2 (ACE2) and angiotensin-(1-7), or peptidases which can modulate the RAS like dipeptidyl-peptidase 3, in many critical situations. In cases of shock, dipeptidyl-peptidase 3, an enzyme involved in the degradation of angiotensin and opioid peptides, has been associated with acute kidney injury and mortality and preclinical studies have tested its neutralization. Angiotensin-(1-7) has been shown to prevent septic shock development and improve outcomes in experimental models of sepsis. In the context of experimental acute lung injury, ACE2 activity has demonstrated a protective role, and its inactivation has been associated with worsened lung function, leading to the use of active recombinant human ACE2, in preclinical and human studies. Angiotensin-(1-7) has been tested in experimental models of acute lung injury and in a recent randomized controlled trial for patients with COVID-19 related hypoxemia. Overall, the alternative RAS appears to have a role in the pathogenesis of disease in critically ill patients, and modulation of the alternative RAS may improve outcomes. Here, we review the available evidence regarding the methods of analysis of the RAS, pathophysiological disturbances of this system, and discuss how therapeutic manipulation may improve outcomes in the critically ill.