Reversal of Vasodilatory Shock: Current Perspectives on Conventional, Rescue, and Emerging Vasoactive Agents for the Treatment of Shock

Effect of rapid and slow intravenous injection of sodium penicillin on arterial blood pressure in isoflurane-anesthetized horses during surgery

OBJECTIVE

To determine the effects of rapid (1 minute) and slow (10 minutes) intravenous (IV) injection of sodium penicillin on arterial blood pressure in anesthetized horses.

STUDY DESIGN

Prospective randomized clinical trial.

ANIMALS

A group of 29 client-owned horses of various breeds, 1-20 years old, with body masses of 360-710 kg.

METHODS

General anesthesia was induced with a variety of anesthetic protocols and maintained with isoflurane under mechanical ventilation, with hourly doses of IV lidocaine and an infusion of dexmedetomidine. Horses were administered IV intraoperative penicillin every 2 hours after the preoperative dose, reconstituted with 50 mL of saline (group small dilution, SD) and administered over 1 minute, or with 250 mL of saline (group large dilution, LD) administered over 10 minutes. Systolic, diastolic and mean arterial blood pressures (SAP, DAP, MAP), heart rate, end-tidal isoflurane and carbon dioxide, dobutamine rate and arterial electrolytes were recorded before and for 20 minutes after penicillin. Comparisons between and within groups were with two-way anova.

RESULTS

Dose and time to penicillin delivery during anesthesia were similar between groups. SAP decreased significantly by 4.8-9.6% (p < 0.0001-0.038), DAP by 12.7-25.4% (p = 0.0009-0.016) and MAP by 6.6-18.4% (p = 0.0009-0.028) from injection and for 15-20 minutes in group SD. In group LD, significant decreases in DAP (13.8-18.5%; p < 0.0001-0.005) and MAP (10.1-13.9%; p < 0.0001-0.003) occurred at 3-15 minutes, and DAP (p = 0.013 and 0.008) and MAP (p = 0.016 and 0.007) were higher than for group SD at 1 and 3 minutes. Dobutamine rate and other variables were similar between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Arterial blood pressure decreased with both SD and LD in anesthetized horses, but to a lesser extent in the slower, more diluted LD group.

Management of Post-cardiotomy Shock

Patients undergoing cardiac surgery experience significant physiologic derangements that place them at risk for multiple shock phenotypes. Any combination of cardiogenic, obstructive, hemorrhagic, or vasoplegic shock occurs commonly in post-cardiotomy patients. The approach to the diagnosis and management of these shock states has many facets that are distinct compared to non-surgical cardiac intensive care unit patients. Additionally, the approach to and associated outcomes of cardiac arrest in the post-cardiotomy population are uniquely characterized by emergent bedside resternotomy if the circulation is not immediately restored. This review focuses on the unique aspects of the diagnosis and management of post-cardiotomy shock.

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.

2024 AAHA Fluid Therapy Guidelines for Dogs and Cats

Fluids are drugs used in veterinary patients capable of producing beneficial therapeutic or inadvertent harmful effects within the body's intravascular, interstitial, and intracellular fluid spaces. The individualized design of a fluid therapy plan requires careful patient assessment and targeted selection of proper fluid types, administration routes, and rates, along with adjustments during therapy tailored specifically as per the individual patient's fluid requirement and therapeutic response. Personalized fluid prescriptions and vigilant patient monitoring help avoid patient morbidity from body fluid deficiencies, fluid excess, and electrolyte derangements and support better patient outcomes. These guidelines provide an overview of fluid dynamics within the fluid spaces of the body, describe various types of fluids and their uses, and outline recommendations for fluid administration for resuscitation, rehydration, and maintenance purposes. The guidelines also outline approaches to fluid therapy for anesthetized patients and reiterate the recommendations of reduced fluid rates in this population of patients. Additionally, the guidelines include practical fluid therapy strategies for patients with various common disorders. The goal of these guidelines is to help veterinary professionals safely and effectively prescribe and administer fluid therapy for canine and feline patients.

Angiotensin II in liver transplantation (AngLT-1): protocol of a randomised, double-blind, placebo-controlled trial

INTRODUCTION

Catecholamine vasopressors such as norepinephrine are the standard drugs used to maintain mean arterial pressure during liver transplantation. At high doses, catecholamines may impair organ perfusion. Angiotensin II is a peptide vasoconstrictor that may improve renal perfusion pressure and glomerular filtration rate, a haemodynamic profile that could reduce acute kidney injury. Angiotensin II is approved for vasodilatory shock but has not been rigorously evaluated for treatment of hypotension during liver transplantation. The objective is to assess the efficacy of angiotensin II as a second-line vasopressor infusion during liver transplantation. This trial will establish the efficacy of angiotensin II in decreasing the dose of norepinephrine to maintain adequate blood pressure. Completion of this study will allow design of a follow-up, multicentre trial powered to detect a reduction of organ injury in liver transplantation.

METHODS AND ANALYSIS

This is a double-blind, randomised clinical trial. Eligible subjects are adults with a Model for End-Stage Liver Disease Sodium Score ≥25 undergoing deceased donor liver transplantation. Subjects are randomised 1:1 to receive angiotensin II or saline placebo as the second-line vasopressor infusion. The study drug infusion is initiated on reaching a norepinephrine dose of 0.05 µg kg-1 min-1 and titrated per protocol. The primary outcome is the dose of norepinephrine required to maintain a mean arterial pressure ≥65 mm Hg. Secondary outcomes include vasopressin or epinephrine requirement and duration of hypotension. Safety outcomes include incidence of thromboembolism within 48 hours of the end of surgery and severe hypertension. An intention-to-treat analysis will be performed for all randomised subjects receiving the study drug. The total dose of norepinephrine will be compared between the two arms by a one-tailed Mann-Whitney U test.

ETHICS AND DISSEMINATION

The trial protocol was approved by the local Institutional Review Board (#20-30948). Results will be posted on ClinicalTrials.gov and published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ClinicalTrials.govNCT04901169.

Trajectory of PaO2/FiO2 Ratio in Shock After Angiotensin II

INTRODUCTION

High-dose catecholamines can impair hypoxic pulmonary vasoconstriction and increase shunt fraction. We aimed to determine if Angiotensin II (Ang-2) is associated with improved PaO2/FiO2 and SpO2/FiO2 in patients in shock.

METHODS

Adult patients at four tertiary care centers and one community hospital in the United States who received Ang-2 from July 2018-September 2020 were included in this retrospective, observational cohort study. PaO2, SpO2, and FiO2 were measured at 13 timepoints during the 48-h before and after Ang-2 initiation. Piecewise linear mixed models of PaO2/FiO2 and SpO2/FiO2 were created to evaluate hourly changes in oxygenation after Ang-2 initiation. The difference in the proportion of patients with PaO2/FiO2 ≤ 300 mm Hg at the time of Ang-2 initiation and 48 h after was also examined.

RESULTS

The study included 254 patients. In the 48 h prior to Ang-2 initiation, oxygenation was significantly declining (hourly PaO2/FiO2 change -4.7 mm Hg/hr, 95% CI - 6.0 to -3.5, p < .001; hourly SpO2/FiO2 change -3.1/hr, 95% CI-3.7 to -2.4, p < .001). Ang-2 treatment was associated with significant improvements in PaO2/FiO2 and SpO2/FiO2 in the 48-h after initiation (hourly PaO2/FiO2 change +1.5 mm Hg/hr, 95% CI 0.5-2.5, p  =  .003; hourly SpO2/FiO2 change +0.9/hr, 95% CI 0.5-1.2, p < .001). The difference in the hourly change in oxygenation before and after Ang-2 initiation was also significant (pinteraction < 0.001 for both PaO2/FiO2 and SpO2/FiO2). This improvement was associated with significantly fewer patients having a PaO2/FiO2 ≤ 300 mm Hg at 48 h compared to baseline (mean difference -14.9%, 95% CI -25.3% to -4.6%, p  =  .011). Subgroup analysis found that patients with either a baseline PaO2/FiO2 ≤ 300 mm Hg or a norepinephrine-equivalent dose requirement >0.2 µg/kg/min had the greatest associations with oxygenation improvement.

CONCLUSIONS

Ang-2 is associated with improved PaO2/FiO2 and SpO2/FiO2. The mechanisms for this improvement are not entirely clear but may be due to catecholamine-sparing effect or may also be related to improved ventilation-perfusion matching, intrapulmonary shunt, or oxygen delivery.

Initiating angiotensin II at lower vasopressor doses in vasodilatory shock: an exploratory post-hoc analysis of the ATHOS-3 clinical trial

BACKGROUND

High dose vasopressors portend poor outcome in vasodilatory shock. We aimed to evaluate the impact of baseline vasopressor dose on outcomes in patients treated with angiotensin II (AT II).

METHODS

Exploratory post-hoc analysis of the Angiotensin II for the Treatment of High-Output Shock (ATHOS-3) trial data. The ATHOS-3 trial randomized 321 patients with vasodilatory shock, who remained hypotensive (mean arterial pressure of 55-70 mmHg) despite receiving standard of care vasopressor support at a norepinephrine-equivalent dose (NED) > 0.2 µg/kg/min, to receive AT II or placebo, both in addition to standard of care vasopressors. Patients were grouped into low (≤ 0.25 µg/kg/min; n = 104) or high (> 0.25 µg/kg/min; n = 217) NED at the time of study drug initiation. The primary outcome was the difference in 28-day survival between the AT II and placebo subgroups in those with a baseline NED ≤ 0.25 µg/kg/min at the time of study drug initiation.

RESULTS

Of 321 patients, the median baseline NED in the low-NED subgroup was similar in the AT II (n = 56) and placebo (n = 48) groups (median of each arm 0.21 µg/kg/min, p = 0.45). In the high-NED subgroup, the median baseline NEDs were also similar (0.47 µg/kg/min AT II group, n = 107 vs. 0.45 µg/kg/min placebo group, n = 110, p = 0.75). After adjusting for severity of illness, those randomized to AT II in the low-NED subgroup were half as likely to die at 28-days compared to placebo (HR 0.509; 95% CI 0.274-0.945, p = 0.03). No differences in 28-day survival between AT II and placebo groups were found in the high-NED subgroup (HR 0.933; 95% CI 0.644-1.350, p = 0.71). Serious adverse events were less frequent in the low-NED AT II subgroup compared to the placebo low-NED subgroup, though differences were not statistically significant, and were comparable in the high-NED subgroups.

CONCLUSIONS

This exploratory post-hoc analysis of phase 3 clinical trial data suggests a potential benefit of AT II introduction at lower doses of other vasopressor agents. These data may inform design of a prospective trial.

TRIAL REGISTRATION

The ATHOS-3 trial was registered in the clinicaltrials.gov repository (no. NCT02338843). Registered 14 January 2015.

Hydroxocobalamin for Vasodilatory Hypotension in Shock: A Systematic Review With Meta-Analysis for Comparison to Methylene Blue

Hydroxocobalamin inhibits nitric oxide-mediated vasodilation, and has been used in settings of refractory shock. However, its effectiveness and role in treating hypotension remain unclear. The authors systematically searched Ovid Medline, Embase, EBM Reviews, Scopus, and Web of Science Core Collection for clinical studies reporting on adult persons who received hydroxocobalamin for vasodilatory shock. A meta-analysis was performed with random-effects models comparing the hemodynamic effects of hydroxocobalamin to methylene blue. The Risk of Bias in Nonrandomized Studies of Interventions tool was used to assess the risk of bias. A total of 24 studies were identified and comprised mainly of case reports (n = 12), case series (n = 9), and 3 cohort studies. Hydroxocobalamin was applied mainly for cardiac surgery vasoplegia, but also was reported in the settings of liver transplantation, septic shock, drug-induced hypotension, and noncardiac postoperative vasoplegia. In the pooled analysis, hydroxocobalamin was associated with a higher mean arterial pressure (MAP) at 1 hour than methylene blue (mean difference 7.80, 95% CI 2.63-12.98). There were no significant differences in change in MAP (mean difference -4.57, 95% CI -16.05 to 6.91) or vasopressor dosage (mean difference -0.03, 95% CI -0.12 to 0.06) at 1 hour compared to baseline between hydroxocobalamin and methylene blue. Mortality was also similar (odds ratio 0.92, 95% CI 0.42-2.03). The evidence supporting the use of hydroxocobalamin for shock is limited to anecdotal reports and a few cohort studies. Hydroxocobalamin appears to positively affect hemodynamics in shock, albeit similar to methylene blue.

Association of Early Norepinephrine Administration With 24-Hour Mortality Among Patients With Blunt Trauma and Hemorrhagic Shock

IMPORTANCE

Hemorrhagic shock is a common cause of preventable death after injury. Vasopressor administration for patients with blunt trauma and hemorrhagic shock is often discouraged.

OBJECTIVE

To evaluate the association of early norepinephrine administration with 24-hour mortality among patients with blunt trauma and hemorrhagic shock.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective, multicenter, observational cohort study used data from 3 registries in the US and France on all consecutive patients with blunt trauma from January 1, 2013, to December 31, 2018. Patients were alive on admission with hemorrhagic shock, defined by prehospital or admission systolic blood pressure less than 100 mm Hg and evidence of hemorrhage (ie, prehospital or resuscitation room transfusion of packed red blood cells, receipt of emergency treatment for hemorrhage control, transfusion of >10 units of packed red blood cells in the first 24 hours, or death from hemorrhage). Blunt trauma was defined as any exposure to nonpenetrating kinetic energy, collision, or deceleration. Statistical analysis was performed from January 15, 2021, to February 22, 2022.

EXPOSURE

Continuous administration of norepinephrine in the prehospital environment or resuscitation room prior to hemorrhage control, according to European guidelines.

MAIN OUTCOMES AND MEASURES

The primary outcome was 24-hour mortality, and the secondary outcome was in-hospital mortality. The average treatment effect (ATE) of early norepinephrine administration on 24-hour mortality was estimated according to the Rubin causal model. Inverse propensity score weighting and the doubly robust approach with 5 distinct analytical strategies were used to determine the ATE.

RESULTS

A total of 52 568 patients were screened for inclusion, and 2164 patients (1508 men [70%]; mean [SD] age, 46 [19] years; median Injury Severity Score, 29 [IQR, 17-36]) presented with acute hemorrhage and were included. A total of 1497 patients (69.1%) required emergency hemorrhage control, 128 (5.9%) received a prehospital transfusion of packed red blood cells, and 543 (25.0%) received a massive transfusion. Norepinephrine was administered to 1498 patients (69.2%). The 24-hour mortality rate was 17.8% (385 of 2164), and the in-hospital mortality rate was 35.6% (770 of 2164). None of the 5 analytical strategies suggested any statistically significant association between norepinephrine administration and 24-hour mortality, with ATEs ranging from -4.6 (95% CI, -11.9 to 2.7) to 2.1 (95% CI, -2.1 to 6.3), or between norepinephrine administration and in-hospital mortality, with ATEs ranging from -1.3 (95% CI, -9.5 to 6.9) to 5.3 (95% CI, -2.1 to 12.8).

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that early norepinephrine infusion was not associated with 24-hour or in-hospital mortality among patients with blunt trauma and hemorrhagic shock. Randomized clinical trials that study the effect of early norepinephrine administration among patients with trauma and hypotension are warranted to further assess whether norepinephrine is safe for patients with hemorrhagic shock.

A Multicenter Observational Cohort Study of Angiotensin II in Shock

INTRODUCTION

Angiotensin II (Ang-2) is a non-catecholamine vasopressor that targets the renin-angiotensin-aldosterone system by agonism of the angiotensin type 1 receptor. Its utility as a vasopressor and a catecholamine-sparing agent was demonstrated in the pivotal ATHOS-3 trial, and numerous post-hoc analyses have shown reduced mortality in certain subsets of the population.

METHODS

Consecutive adult patients at 5 centers who received Ang-2 from 2017-2020 were included in this multicenter, retrospective observational cohort study. Patient demographics, hemodynamics, and adverse events were collected. The primary outcomes of the study were the mean difference in MAP and norepinephrine (NEpi)-equivalent dose at hours 0 and 3 following initiation of Ang-2 therapy.

RESULTS

One hundred and sixty-two patients were included in this study. The primary outcomes of an increase in MAP (mean difference 9.3 mmHg, 95% CI 6.4-12.1, p < 0.001) and a reduction in NEpi equivalent dose (mean difference 0.16 µg/kg/min, 95% CI 0.10-0.22, p < 0.001) between hours 0 and 3 were statistically significant. The median time to reach a MAP ≥65 was 16 minutes (IQR 5-60 min). After stratifying patients by the NED dose and number of vasopressors administered prior to the initiation of Ang-2, those with a NED dose < 0.2 µg/kg/min, NED dose < 0.3 µg/kg/min, or those on ≤ 3 vasopressors had a significantly greater reduction in NED by hour 3 than those patients above these thresholds.

CONCLUSION

Ang-2 is an effective vasopressor and reduces catecholamine dose significantly. Its effect is rapid, with target MAP obtained within 30 minutes in most patients. Given the critical importance of adequate blood pressure to organ perfusion, Ang-2 should be considered when target MAP cannot be achieved with conventional vasopressors. Ang-2 should be utilized early in the course of shock, before the NED dose exceeds 0.2-0.3 µg/kg/min and before the initiation of the fourth-line vasopressor.

Enhanced recovery after surgery: Current status and future progress

Enhanced Recovery After Surgery (ERAS) pathways were first introduced almost a quarter of a century ago and represent a paradigm shift in perioperative care that reduced postoperative complications and hospital length of stay, improved postoperative quality of life, and reduced overall healthcare costs. Gradual recognition of the generalizability of the interventions and transferable improvements in postoperative outcomes, led them to become standard of care for several surgical procedures. In this article, we critically review the current status of ERAS pathways, address related controversies, and propose measures for future progress.

Effects of a single bolus of hydroxocobalamin on hemodynamics in vasodilatory shock

PURPOSE

Hydroxocobalamin has been observed to cause transient hypertension in healthy subjects, but rigorous studies examining its efficacy are lacking.

MATERIALS AND METHODS

Adults in shock who received hydroxocobalamin from 2017 to 2021 were analyzed retrospectively. Hourly hemodynamics from 24 h before and after treatment were collected, and the difference and hourly change of mean arterial pressure (MAP), systolic blood pressure (SBP), diastolic blood pressure (DBP), and norepinephrine-equivalent dose (NED) were examined in mixed-effects models.

RESULTS

This study included 3992 hemodynamic data points from 35 patients and is the largest case series to date. In the mixed effects model, there was no difference in MAP 24-h after hydroxocobalamin administration (estimated fixed effect [EFE] -0.2 mmHg, p = 0.89). A two-piecewise mixed model found that the hourly change in MAP was not different from zero in either the pre-administration (EFE 0.0 mmHg/h, p = 0.80) or post-administration segments (EFE 0.0 mmHg/h, p = 0.55). Analysis of the SBP, DBP, and NED also found similar insignificant results.

CONCLUSIONS

Although hydroxocobalamin has been observed to cause hypertension in healthy subjects, our results suggest that in patients with shock, hydroxocobalamin may not be effective in improving hemodynamics at 24 h after administration.

Dysregulation of the renin-angiotensin system in septic shock: Mechanistic insights and application of angiotensin II in clinical management

Synergistic physiologic mechanisms involving the renin-angiotensin system (RAS), the sympathetic nervous system, and the arginine-vasopressin system play an integral role in blood pressure homeostasis. A subset of patients with sepsis experience septic shock with attendant circulatory, cellular, and metabolic abnormalities. Septic shock is associated with increased mortality because of an inadequacy to maintain mean arterial blood pressure (MAP) despite volume resuscitation and the use of vasopressors. Vasodilatory shock raises the dose of vasopressors required to maintain a MAP of > 65 mm Hg. The diminished response to endogenous angiotensin II in sepsis-induced vasoplegia may be related to the aberrant RAS activation that stimulates a proinflammatory beneficial antibacterial response, increasing the secretion of proinflammatory cytokines that downregulate AT-1 receptors expression. Moreover, excessive systemic upregulation of nitric oxide synthase, stimulation of prostaglandin synthesis, and activation of ATP-sensitive potassium channels followed by reduced vascular entry of calcium ions are putative mechanisms in the reduced responsiveness to vasopressors. However, intravenous angiotensin II in catecholamine-resistant septic shock patients showed substantial evidence of raising the MAP to target hemodynamic levels, thus allowing time to treat underlying conditions. Nevertheless, evidence of catecholamine-sparing effect by adding angiotensin II, aimed at increasing the therapeutic index of vasopressor therapy, does not show an attenuation of end-organ damage. The use of angiotensin II in septic shock has not been evaluated in patients who are not catecholamine resistant. This, in conjunction with an evolving definition of catecholamine resistance, provides an opportunity for further evaluation of exogenous angiotensin II in septic shock.

Vasopressors in Trauma: A Never Event?

Vasopressor use in severely injured trauma patients is discouraged due to concerns that vasoconstriction will worsen organ perfusion and result in increased mortality and organ failure in hypotensive trauma patients. Hypotensive resuscitation is advocated based on limited data that lower systolic blood pressure and mean arterial pressure will result in improved mortality. It is classically taught that hypotension and hypovolemia in trauma are associated with peripheral vasoconstriction. However, the pathophysiology of traumatic shock is complex and involves multiple neurohormonal interactions that are ultimately manifested by an initial sympathoexcitatory phase that attempts to compensate for acute blood loss and is characterized by vasoconstriction, tachycardia, and preserved mean arterial blood pressure. The subsequent hypotension observed in hemorrhagic shock reflects a sympathoinhibitory vasodilation phase. The objectives of hemodynamic resuscitation in hypotensive trauma patients are restoring adequate intravascular volume with a balanced ratio of blood products, correcting pathologic coagulopathy, and maintaining organ perfusion. Persistent hypotension and hypoperfusion are associated with worse coagulopathy and organ function. The practice of hypotensive resuscitation would appear counterintuitive to the goals of traumatic shock resuscitation and is not supported by consistent clinical data. In addition, excessive volume resuscitation is associated with adverse clinical outcomes. Therefore, in the resuscitation of traumatic shock, it is necessary to target an appropriate balance with intravascular volume and vascular tone. It would appear logical that vasopressors may be useful in traumatic shock resuscitation to counteract vasodilation in hemorrhage as well as other clinical conditions such as traumatic brain injury, spinal cord injury, multiple organ dysfunction syndrome, and vasodilation of general anesthetics. The purpose of this article is to discuss the controversy of vasopressors in hypotensive trauma patients and advocate for a nuanced approach to vasopressor administration in the resuscitation of traumatic shock.

Renin Kinetics Are Superior to Lactate Kinetics for Predicting In-Hospital Mortality in Hypotensive Critically Ill Patients

OBJECTIVES

Whole blood lactate concentration is widely used in shock states to assess perfusion. We aimed to determine if the change in plasma renin concentration over time would be superior to the change in lactate concentration for predicting in-hospital mortality in hypotensive patients on vasopressors.

DESIGN

Prospective, observational cohort study.

SETTING

Tertiary academic ICU.

PATIENTS

Adult patients on vasopressors for greater than 6 hours to maintain a mean arterial pressure greater than or equal to 65 mm Hg during January 2020.

INTERVENTIONS

Plasma renin concentrations were measured at enrollment and at 24, 48, and 72 hours. Whole blood lactate measurements were performed according to normal standard of care. Logistic regression was performed to evaluate whether the change in renin or lactate concentration could predict in-hospital mortality. Generalized estimating equations were used to analyze the association between renin and lactate concentration and in-hospital mortality. The area under the receiver operating characteristics curve was performed to measure the discriminative ability of initial and peak renin and lactate concentration to predict mortality. The association between renin and lactate concentration above the upper limit of normal at each timepoint with in-hospital mortality was also examined.

MEASUREMENTS AND MAIN RESULTS

The study included 197 renin and 148 lactate samples obtained from 53 patients. The slope of the natural log (ln) of renin concentration was independently associated with mortality (adjusted odds ratio, 10.35; 95% CI, 1.40-76.34; p = 0.022), but the slope of ln-lactate concentration was not (adjusted odds ratio, 4.78; 95% CI, 0.03-772.64; p = 0.55). The generalized estimating equation models found that both ln-renin (adjusted odds ratio, 1.18; 95% CI, 1.02-1.37; p = 0.025) and ln-lactate (adjusted odds ratio, 2.38; 95% CI, 1.05-5.37; p = 0.037) were associated with mortality. Area under the receiver operating characteristics curve analysis demonstrated that initial renin could predict in-hospital mortality with fair discrimination (area under the receiver operating characteristics curve, 0.682; 95% CI, 0.503-0.836; p = 0.05), but initial lactate could not (area under the receiver operating characteristics curve, 0.615; 95% CI, 0.413-0.803; p = 0.27). Peak renin (area under the receiver operating characteristics curve, 0.728; 95% CI, 0.547-0.888; p = 0.01) and peak lactate (area under the receiver operating characteristics curve, 0.746; 95% CI, 0.584-0.876; p = 0.01) demonstrated moderate discrimination. There was no significant difference in discriminative ability between initial or peak renin and lactate concentration. At each study time point, a higher proportion of renin values exceeded the threshold of normal (40 pg/mL) in nonsurvivors than in survivors, but this association was not significant for lactate.

CONCLUSIONS

Although there was no significant difference in the performance of renin and lactate when examining the absolute values of each laboratory, a positive rate of change in renin concentration, but not lactate concentration, over 72 hours was associated with in-hospital mortality. For each one-unit increase in the slope of ln-renin, the odds of mortality increased 10-fold. Renin levels greater than 40 pg/mL, but not lactate levels greater than 2 mmol/L, were associated with in-hospital mortality. These findings suggest that plasma renin kinetics may be superior to lactate kinetics in predicting mortality of hypotensive, critically ill patients.

Fluid Resuscitation for Refractory Hypotension

Hypotension is a common occurrence, especially in anesthetized patients and in critical patients suffering from hypovolemia due to shock and sepsis. Hypotension can also occur in normovolemic animals, anesthetized or conscious, under conditions of vasodilation or decreased cardiac function. The main consequence of hypotension is decreased organ perfusion and tissue injury/dysfunction. In the human literature there is no consensus on what is the threshold value for hypotension, and ranges from < 80 to < 100 mmHg for systolic blood pressure and from < 50 to < 70 mmHg for mean arterial blood pressure have been referenced for intraoperative hypotension. In veterinary medicine, similar values are referenced, despite marked differences in normal arterial blood pressure between species and with respect to humans. Therapeutic intervention involves fluid therapy to normalize volemia and use of sympathomimetics to enhance cardiac function and regulate peripheral vascular resistance. Despite these therapeutic measures, there is a subset of patients that are seemingly refractory and exhibit persistent hypotension. This review covers the physiological aspects that govern arterial blood pressure control and blood flow to tissues/organs, the pathophysiological mechanisms involved in hypotension and refractory hypotension, and therapeutic considerations and expectations that include proper interpretation of cardiovascular parameters, fluid recommendations and therapy rates, use of sympathomimetics and vasopressors, and newer approaches derived from the human literature.

Roles of angiotensin II as vasopressor in vasodilatory shock

Shock is an acute condition of circulatory failure resulting in life-threatening organ dysfunction, high morbidity and high mortality. Current management includes fluid and catecholamine therapy to maintain adequate mean arterial pressure and organ perfusion. Norepinephrine is recommended as first-line vasopressor, but other agents are available. Angiotensin II is an alternative potent vasoconstrictor without chronotropic or inotropic properties. Several studies, including a large randomized controlled trial have demonstrated its ability to increase blood pressure with catecholamine-sparing effects. Angiotensin II was consequently approved by the US FDA in 2017 and the EU in 2019 as an add-on vasopressor in vasodilatory shock. This review aims to discuss its basic pharmacology, clinical efficacy, safety and future perspectives.

Circulating dipeptidyl peptidase-3 at admission is associated with circulatory failure, acute kidney injury and death in severely ill burn patients

Background

Dipeptidyl peptidase-3 (DPP3) is a metallopeptidase which cleaves bioactive peptides, notably angiotensin II, and is involved in inflammation regulation. DPP3 has been proposed to be a myocardial depressant factor and to be involved in circulatory failure in acute illnesses, possibly due to angiotensin II cleavage. In this study, we evaluated the association between plasmatic DPP3 level and outcome (mortality and hemodynamic failure) in severely ill burn patients.

Methods

In this biomarker analysis of a prospective cohort study, we included severely ill adult burn patients in two tertiary burn intensive care units. DPP3 was measured at admission (DPP3_admin) and 3 days after. The primary endpoint was 90-day mortality. Secondary endpoints were hemodynamic failure and acute kidney injury (AKI).

Results

One hundred and eleven consecutive patients were enrolled. The median age was 48 (32.5–63) years, with a median total body surface area burned of 35% (25–53.5) and Abbreviated Burn Severity Index (ABSI) of 8 (7–11). Ninety-day mortality was 32%. The median DPP3_admin was significantly higher in non-survivors versus survivors (53.3 ng/mL [IQR 28.8–103.5] versus 27.1 ng/mL [IQR 19.4–38.9]; p < 0.0001). Patients with a sustained elevated DPP3 had an increased risk of death compared to patients with high DPP3_admin but decreased levels on day 3. Patients with circulatory failure had higher DPP3_admin (39.2 ng/mL [IQR 25.9–76.1] versus 28.4 ng/mL [IQR 19.8–39.6]; p = 0.001) as well as patients with AKI (49.7 ng/mL [IQR 30.3–87.3] versus 27.6 ng/mL [IQR 19.4–41.4]; p = 0.001). DPP3_admin added prognostic value on top of ABSI (added chi² 12.2, p = 0.0005), Sequential Organ Failure Assessment (SOFA) score at admission (added chi² 4.9, p = 0.0268), and plasma lactate at admission (added chi² 6.9, p = 0.0086) to predict circulatory failure within the first 48 h.

Conclusions

Plasma DPP3 concentration at admission was associated with an increased risk of death, circulatory failure, and AKI in severely burned patients. Whether DPP3 plasma levels could identify patients who would respond to alternative hemodynamic support strategies, such as intravenous angiotensin II, should be explored.

Angiotensin II and Vasopressin for Vasodilatory Shock: A Critical Appraisal of Catecholamine-Sparing Strategies

Vasodilatory shock is a serious medical condition that increases the morbidity and mortality of perioperative and critically ill patients. Norepinephrine is an established first-line therapy for this condition, but at high doses, it may lead to diminishing returns. Oftentimes, secondary noncatecholamine agents are required in those whose hypotension persists. Angiotensin II and vasopressin are both noncatecholamine agents available for the treatment of hypotension in vasodilatory shock. They have distinct modes of action and unique pharmacologic properties when compared to norepinephrine. Angiotensin II and vasopressin have shown promise in certain subsets of the population, such as those with acute kidney injury, high Acute Physiology and Chronic Health Evaluation II scores, or those receiving cardiac surgery. Any benefit from these drugs must be weighed against the risks, as overall mortality has not been shown to decrease mortality in the general population. The aims of this narrative review are to provide insight into the historical use of noncatecholamine vasopressors and to compare and contrast their unique modes of action, physiologic rationale for administration, efficacy, and safety profiles.

Angiotensin II for the emergency physician

Refractory hypotension is one of the most common and difficult clinical problems faced by acute care clinicians, and it poses a particularly large problem to the emergency physician when a patient in undifferentiated shock arrives in the department. Angiotensin II (Ang-2) has been previously used as a vasopressor to combat shock; the feasibility of its clinical use has been reinvigorated after approval of a human synthetic formulation of the medication by the US Food and Drug Administration in 2017 and the European Medicines Agency in 2019. A thorough literature search was completed, and in this review, we discuss the discovery and development of Ang-2, its complex mechanisms of vasoconstriction, its potential adverse effects and its potential role in clinical practice for emergency physicians.

Vasoplegia During Cardiopulmonary Bypass: Current Literature and Rescue Therapy Options

Vasoplegia syndrome in the cardiac surgical intensive care unit and postoperative period has been an area of interest to clinicians because of its prevalence and effects on morbidity and mortality. However, there is a paucity of evidence regarding the treatment of vasoplegia syndrome during cardiopulmonary bypass (on-CPB VS). This review aims to detail the incidence, outcomes, and possible treatment options for patients who develop vasoplegia during bypass. The pharmacologic rescue agents discussed are used in cases in which vasoplegia during CPB is refractory to standard catecholamine agents, such as norepinephrine, epinephrine, and phenylephrine. Methods to improve vasoplegia during CPB can be both pharmacologic and nonpharmacologic. In particular, optimization of CPB parameters plays an important nonpharmacologic role in vasoplegia during CPB. Pharmacologic agents that have been demonstrated as being effective in vasoplegia include vasopressin, terlipressin, methylene blue, hydroxocobalamin, angiotensin II (Giapreza), vitamin C, flurbiprofen (Ropion), and hydrocortisone. Although these agents have not been specifically evaluated for vasoplegia during CPB, they have shown signs of effectiveness for vasoplegia postoperatively to varying degrees. Understanding the evidence for, dosing, and side effects of these agents is crucial for cardiac anesthesiologists when treating vasoplegia during CPB bypass.