Role of arginine vasopressin and terlipressin as first-line vasopressor agents in fulminant ovine septic shock

Long-Circulating Vasoactive 1,18-Octadecanedioic Acid-Terlipressin Conjugate

Hepatorenal syndrome (HRS) is a life-threatening complication of end-stage liver disease first reported over a century ago, but its management still poses an unmet challenge. A therapeutic agent found to stabilize the condition is a short cyclic peptide, vasopressin analogue, terlipressin (TP). While TP is commonly prescribed for HRS patients in most parts of the world, it was only recently approved for use in the United States. TP exhibits short circulation half-lives and adverse side effects associated with the dose required. Herein, we present a 1,18-octadecanedioic acid (ODDA) conjugate of the cyclic peptide (ODDA-TP), which enables noncovalent binding to serum albumin via native fatty acid binding modes. ODDA-TP is demonstrated to outperform TP alone in studies including in vitro cellular receptor activation, stability in plasma, pharmacokinetics, and performance in vivo in rats. Specifically, ODDA-TP had an elimination half-life 20 times that of TP alone while exhibiting a superior safety profile.

Arginine vasopressin hormone receptor antagonists in experimental autoimmune encephalomyelitis rodent models: A new approach for human multiple sclerosis treatment

Multiple sclerosis (MS) is a chronic demyelinating and neurodegenerative disease that affects the central nervous system. MS is a heterogeneous disorder of multiple factors that are mainly associated with the immune system including the breakdown of the blood-brain and spinal cord barriers induced by T cells, B cells, antigen presenting cells, and immune components such as chemokines and pro-inflammatory cytokines. The incidence of MS has been increasing worldwide recently, and most therapies related to its treatment are associated with the development of several secondary effects, such as headaches, hepatotoxicity, leukopenia, and some types of cancer; therefore, the search for an effective treatment is ongoing. The use of animal models of MS continues to be an important option for extrapolating new treatments. Experimental autoimmune encephalomyelitis (EAE) replicates the several pathophysiological features of MS development and clinical signs, to obtain a potential treatment for MS in humans and improve the disease prognosis. Currently, the exploration of neuro-immune-endocrine interactions represents a highlight of interest in the treatment of immune disorders. The arginine vasopressin hormone (AVP) is involved in the increase in blood−brain barrier permeability, inducing the development and aggressiveness of the disease in the EAE model, whereas its deficiency improves the clinical signs of the disease. Therefore, this present review discussed on the use of conivaptan a blocker of AVP receptors type 1a and type 2 (V1a and V2 AVP) in the modulation of immune response without completely depleting its activity, minimizing the adverse effects associated with the conventional therapies becoming a potential therapeutic target in the treatment of patients with multiple sclerosis.

Effects of Terlipressin on Management of Hypotensive Brain-Dead Patients Who are Potential Organ Donors: A Retrospective Study

Background: Administration of terlipressin can reverse hypotension in potential organ donors with norepinephrine-resistance. The aim of this study was to determine the effects of terlipressin on the hemodynamics, liver function, and renal function of hypotensive brain-dead patients who were potential organ donors.

Methods: A retrospective study was conducted by using the ICU database of one hospital. 18 patients in a total of 294 brain-dead cases were enrolled and administered terlipressin intravenously. All physiological parameters of recruited patients were obtained at baseline, 24 and 72 h after administration, and immediately before organ procurement.

Results: Terlipressin induced significant increases in mean arterial pressure (MAP) from 69.56 ± 10.68 mm Hg (baseline) to 101.82 ± 19.27 mm Hg (immediately before organ procurement) and systolic blood pressure (SBP) from 89.78 ± 8.53 mm Hg (baseline) to 133.42 ± 26.11 mm Hg (immediately before organ procurement) in all patients. The increases in MAP were accompanied by significant decreases in heart rate (HR) from 113.56 ± 28.43 bpm (baseline) to 83.89 ± 11.70 bpm (immediately before organ procurement), which resulted in the decrease of norepinephrine dose over time from 0.8 ± 0.2 μg/kg/min (baseline) to 0.09 ± 0.02 μg/kg/min (immediately before organ procurement). There were no changes in central venous pressure, liver function including aspartate aminotransferase (AST), alanine aminotransferase (ALT), and bilirubin. Renal function, assessed by serum creatinine (SCr), urine output (UOP), creatinine clearance rate (CCr), and estimated glomerular filtration rate (eGFR), improved significantly.

Conclusion: Our analysis of brain-dead patients with hypotension indicates that administration of terlipressin can significantly increases MAP, SBP, UOP, CCr, and eGFR, while decreases HR and Scr. Terlipressin appears to help maintain hemodynamic stability, reduce vasoactive support, and improve renal function.

Terlipressin for the treatment of septic shock in adults: a systematic review and meta-analysis

Background

Catecholamines are the first-line vasopressors used in patients with septic shock. However, the search for novel drug candidates is still of great importance due to the development of adrenergic hyposensitivity accompanied by a decrease in catecholamine activity. Terlipressin (TP) is a synthetic vasopressin analogue used in the management of patients with septic shock. In the current study, we aimed to compare the effects of TP and catecholamine infusion in treating septic shock patients.

Methods

A systematic review and meta-analysis was conducted by searching articles published in PUBMED, EMBASE, and the Cochrane Central Register of Controlled Trials between inception and July 2018. We only selected randomized controlled trials evaluating the use of TP and catecholamine in adult patients with septic shock. The primary outcome was overall mortality. The secondary outcomes were the ICU length of stay, haemodynamic changes, tissue perfusion, renal function, and adverse events.

Results

A total of 9 studies with 850 participants were included in the analysis. Overall, no significant difference in mortality was observed between the TP and catecholamine groups (risk ratio(RR), 0.85 (0.70 to 1.03); P = 0.09). In patients < 60 years old, the mortality rate was lower in the TP group than in the catecholamine group (RR, 0.66 (0.50 to 0.86); P = 0.002). There was no significant difference in the ICU length of stay (mean difference, MD), − 0.28 days; 95% confidence interval (CI), − 1.25 to 0.69; P = 0.58). Additionally, TP improved renal function. The creatinine level was decreased in patients who received TP therapy compared to catecholamine-treated participants (standard mean difference, SMD), − 0.65; 95% CI, − 1.09 to − 0.22; P = 0.003). No significant difference was found regarding the total adverse events (Odds Ratio(OR), 1.48(0.51 to 4.24); P = 0.47), whereas peripheral ischaemia was more common in the TP group (OR, 8.65(1.48 to 50.59); P = 0.02).

Conclusion

The use of TP was associated with reduced mortality in septic shock patients less than 60 years old. TP may also improve renal function and cause more peripheral ischaemia. PROSPERO registry: CRD42016035872.

Terlipressin Versus Norepinephrine for Septic Shock: A Systematic Review and Meta-Analysis

Purpose: The meta-analysis aims to evaluate the efficacy and safety of terlipressin compared with norepinephrine for septic shock.

Materials and Methods: The relevant studies from MEDLINE, Cochrane Library, Embase were searched by two independent investigators. A variety of keywords were used to search the studies. Stata software (version 11.0, Stata Corp LP, College Station, TX, USA) was used for statistical analysis.

Results: A total of six studies were identified and incorporated into the meta-analysis. The results showed that there was no difference for 28-day mortality (RR = 0.99, 95% CI = [0.85,1.15], P = 0.849), AE (RR = 2.54, 95% CI = [0.58,11.08], P = 0.214), and MAP (SMD = -0.10, 95% CI = [-0.35,0.14], P = 0.405), OI, urinary output, Scr, total bilirubin, ALT, and AST between TP group and NE group. While TP could decrease HR at 24 and 48 h compared with NE.

Conclusions: Current results suggest that terlipressin showed no added survival benefit for septic shock when compared with norepinephrine, while terlipressin could decrease heart rate in the late phase of septic shock compared with norepinephrine without further liver and kidney injury.

Systematic Review Registration: PROSPERO (ID: CRD42019128743). Available online at: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42019128743.

Renal autoregulation in experimental septic shock and its response to vasopressin and norepinephrine administration

Evidence suggests that septic shock patients with chronic arterial hypertension may benefit from resuscitation targeted to achieve higher blood pressure values than other patients, possibly as a result of altered renal autoregulation. The effects of different vasopressor agents on renal autoregulation may be important in this context. We investigated the effects of arginine vasopressin (AVP) and norepinephrine (NE) on renal autoregulation in ovine septic shock. Sepsis was induced by fecal peritonitis. When shock developed (decrease in mean arterial pressure to <65 mmHg and no fluid-responsiveness), animals were randomized to receive NE or AVP in a crossover design. Before the switch to the second vasopressor, the first vasopressor was discontinued for 30 minutes to ensure complete washout of the first vasopressor. Renal autoregulation was evaluated by recording the change in renal blood flow (RBF) in response to manual, stepwise reductions in renal inflow pressure. In this model, the lower limit of renal autoregulation was not significantly altered 6 hours after sepsis induction (59±9 vs. 64±7 mmHg at baseline, p=0.096). After development of shock, the autoregulatory threshold was lower with AVP than with NE (59±5 vs. 65±7 mmHg, p=0.010). However, RBF was higher with NE both at the start of autoregulatory measurements (206±58 vs. 170±52 mL/min; p=0.050) and at the autoregulatory threshold (191±53 vs. 150±47 mL/min; p=0.008). As vasopressors may have different effects on renal autoregulation, blood pressure management in patients with septic shock should be individualized and take into account drug-specific effects.

Terlipressin versus norepinephrine as infusion in patients with septic shock: a multicentre, randomised, double-blinded trial

PURPOSE

Recent clinical data suggest that terlipressin, a vasopressin analogue, may be more beneficial in septic shock patients than catecholamines. However, terlipressin's effect on mortality is unknown. We set out to ascertain the efficacy and safety of continuous terlipressin infusion compared with norepinephrine (NE) in patients with septic shock.

METHODS

In this multicentre, randomised, double-blinded trial, patients with septic shock recruited from 21 intensive care units in 11 provinces of China were randomised (1:1) to receive either terlipressin (20-160 µg/h with maximum infusion rate of 4 mg/day) or NE (4-30 µg/min) before open-label vasopressors. The primary endpoint was mortality 28 days after the start of infusion. Primary efficacy endpoint analysis and safety analysis were performed on the data from a modified intention-to-treat population.

RESULTS

Between 1 January 2013 and 28 February 2016, 617 patients were randomised (312 to the terlipressin group, 305 to the NE group). The modified intention-to-treat population comprised 526 (85.3%) patients (260 in the terlipressin group and 266 in the NE group). There was no significant difference in 28-day mortality rate between the terlipressin group (40%) and the NE group (38%) (odds ratio 0.93 [95% CI 0.55-1.56]; p = 0.80). Change in SOFA score on day 7 was similar between the two groups: - 7 (IQR - 11 to 3) in the terlipressin group and - 6 (IQR - 10 to 5) in the NE group. There was no difference between the groups in the number of days alive and free of vasopressors. Overall, serious adverse events were more common in the terlipressin group than in the NE group (30% vs 12%; p < 0.001).

CONCLUSIONS

In this multicentre, randomised, double-blinded trial, we observed no difference in mortality between terlipressin and NE infusion in patients with septic shock. Patients in the terlipressin group had a higher number of serious adverse events.

TRIAL REGISTRATION

This trial is registered at ClinicalTrials.gov: ID NCT01697410.

Comparison of first-line and second-line terlipressin versus sole norepinephrine in fulminant ovine septic shock

The Surviving Sepsis Guidelines suggest the use of vasopressin in case of catecholamine-refractory septic shock. Terlipressin (TP) as a V₁-selective AVP analogue is a potential alternative, though data regarding the first-line administration in septic shock are scarce. The present study explored and compared the effects of first-line vs. second-line infusion of TP or sole norepinephrine regarding organ function, fluid and norepinephrine requirements and survival in fulminant ovine septic shock. Peritoneal sepsis was induced in 23 ewes after laparotomy and faecal withdrawal from the caecum. After onset of shock, causal and supportive sepsis therapy (antibiotics, peritoneal lavage, fluids and open-label norepinephrine) was performed in all animals. Concurrently, animals were randomized to receive 0.9% sodium chloride (control group) or TP (2 µg∙kg^-1∙h^-1, first-line group) after shock onset. In the second-line TP group, TP (2 µg∙kg^-1∙h^-1) was started once norepinephrine requirements exceeded 0.5 µg∙kg^-1∙min^-1. No significant differences were found between groups regarding survival, haemodynamics as well as fluid- and catecholamine-requirements. Kidney function and electron microscopic kidney injury were comparable between groups. In the present model of fulminant ovine septic shock, first-line TP infusion had no significant effect on fluid and norepinephrine requirements or organ dysfunction as compared to second-line TP infusion or placebo.

Provision of physiological data and reference values in awake and anaesthetized female sheep aged 6-12 months

OBJECTIVE

To provide physiological data and reference values in awake and anaesthetized sheep aged 6-12 months.

STUDY DESIGN

Descriptive study.

ANIMALS

Data from 260 female sheep of the species Ovis orientalis aries aged 6-12 months were extracted from 10 experimental trials.

METHODS

Data from pulmonary arterial thermodilution in awake (cohort 1; n = 109) and anaesthetized animals (cohort 2; n = 81), and transpulmonary thermodilution in anaesthetized animals (cohort 3; n = 70) were analysed. General anaesthesia was induced by intramuscular injection of S-ketamine and midazolam and maintained by inhaled isoflurane. Standard laboratory variables (blood gas and clinical chemistry) were assessed.

RESULTS

A total of 7553 single data entries from 260 healthy sheep were included. Measurement errors or invalid data documentation meant that 313 data entries (4.1%) were excluded. A small confidence interval for median values was calculated for nearly all variables. The median body weight was 39.8 kg (2.5-97.5th percentile 30.6-48.1 kg). A set of reference values (2.5-97.5th percentiles) is provided for common cardiopulmonary and laboratory variables. Compared to awake animals, haemodynamic variables were markedly influenced by anaesthesia, as reflected by a considerably lower stroke volume index in anaesthetized sheep. There were also differences in stroke volume index between the cohorts of pulmonary artery and transpulmonary thermodilution.

CONCLUSIONS AND CLINICAL RELEVANCE

The present work presents a large and consistent database of a variety of physiological variables measured in healthy juvenile female sheep. The data appear to be robust and allow the establishment of standardized inclusion criteria for experimental studies and may help to better evaluate past, present and future research. Differences between pulmonary artery and transpulmonary thermodilution should be assessed in future studies.

A Selective V(1A) Receptor Agonist, Selepressin, Is Superior to Arginine Vasopressin and to Norepinephrine in Ovine Septic Shock

OBJECTIVE

Selective vasopressin V(1A) receptor agonists may have advantages over arginine vasopressin in the treatment of septic shock. We compared the effects of selepressin, a selective V(1A) receptor agonist, arginine vasopressin, and norepinephrine on hemodynamics, organ function, and survival in an ovine septic shock model.

DESIGN

Randomized animal study.

SETTING

University hospital animal research laboratory.

SUBJECTS

Forty-six adult female sheep.

INTERVENTIONS

Fecal peritonitis was induced in the anesthetized, mechanically ventilated, fluid-resuscitated sheep, and they were randomized in two successive phases. Three late-intervention groups (each n = 6) received IV selepressin (1 pmol/kg/min), arginine vasopressin (0.25 pmol [0.1 mU]/kg/min), or norepinephrine (3 nmol [0.5 μg]/kg/min) when mean arterial pressure remained less than 70 mm Hg despite fluid challenge; study drugs were thereafter titrated to keep mean arterial pressure at 70-80 mm Hg. Three early-intervention groups (each n = 7) received selepressin, arginine vasopressin, or norepinephrine at the same initial infusion rates as for the late intervention, but already when mean arterial pressure had decreased by 10% from baseline; doses were then titrated as for the late intervention. A control group (n = 7) received saline. All animals were observed until death or for a maximum of 30 hours.

MEASUREMENTS AND MAIN RESULTS

In addition to hemodynamic and organ function assessment, plasma interleukin-6 and nitrite/nitrate levels were measured. In the late-intervention groups, selepressin delayed the decrease in mean arterial pressure and was associated with lower lung wet/dry weight ratios than in the other two groups. In the early-intervention groups, selepressin maintained mean arterial pressure and cardiac index better than arginine vasopressin or norepinephrine, slowed the increase in blood lactate levels, and was associated with less lung edema, lower cumulative fluid balance, and lower interleukin-6 and nitrite/nitrate levels. Selepressin-treated animals survived longer than the other animals.

CONCLUSIONS

In this clinically relevant model, selepressin, a selective V(1A) receptor agonist, was superior to arginine vasopressin and to norepinephrine in the treatment of septic shock, especially when administered early.

Terlipressin decreases vascular endothelial growth factor expression and improves oxygenation in patients with acute respiratory distress syndrome and shock

BACKGROUND

Recent clinical data suggest that treatment with terlipressin (TP) may be more advantageous for septic shock than catecholamines. However, it is unknown whether TP would be effective for acute respiratory distress syndrome (ARDS) patients with shock.

OBJECTIVES

The aim of this study was to compare the impact of TP vs. dopamine on hemodynamic variables and vascular endothelial growth factor (VEGF) in ARDS patients with shock.

METHODS

We studied 32 ARDS patients with shock despite fluid loading, who were randomized to receive TP (16 patients) or dopamine (16 patients). TP was administered as a continuous intravenous dose of 1.3 μg/kg/h and dopamine was administered in doses up to 20 μg/kg/min to maintain a mean arterial pressure of 70 ± 5 mm Hg for 48 h. Hemodynamic changes, ratio of partial pressure of arterial oxygen to fraction of inspired oxygen (PaO(2)/FiO(2)), and VEGF were recorded prospectively.

RESULTS

There was a significant correlation between the plasma VEGF level and the lung injury score at baseline (r = 0.387, p < 0.01). VEGF concentrations significantly decreased from baseline levels in the TP group (p < 0.05) at 48 h; there was no difference in the dopamine group (p > 0.05) at 48 h vs. baseline. There was no significant difference in the tumor necrosis factor-α concentration between the groups.

CONCLUSIONS

TP treatment has the potential to inhibit VEGF and improve oxygenation in patients with shock in the early stage of ARDS.

Selective V(1a) agonism attenuates vascular dysfunction and fluid accumulation in ovine severe sepsis

Vasopressin analogs are used as a supplement to norepinephrine in septic shock. The isolated effects of vasopressin agonists on sepsis-induced vascular dysfunction, however, remain controversial. Because V(2)-receptor stimulation induces vasodilation and procoagulant effects, a higher V(1a)- versus V(2)-receptor selectivity might be advantageous. We therefore hypothesized that a sole, titrated infusion of the selective V(1a)-agonist Phe(2)-Orn(8)-Vasotocin (POV) is more effective than the mixed V(1a)-/V(2)-agonist AVP for the treatment of vascular and cardiopulmonary dysfunction in methicillin resistant staphylococcus aureus pneumonia-induced, ovine sepsis. After the onset of hemodynamic instability, awake, chronically instrumented, mechanically ventilated, and fluid resuscitated sheep were randomly assigned to receive continuous infusions of either POV, AVP, or saline solution (control; each n = 6). AVP and POV were titrated to maintain mean arterial pressure above baseline - 10 mmHg. When compared with that of control animals, AVP and POV reduced neutrophil migration (myeloperoxidase activity, alveolar neutrophils) and plasma levels of nitric oxide, resulting in higher mean arterial pressures and a reduced vascular leakage (net fluid balance, chest and abdominal fluid, pulmonary bloodless wet-to-dry-weight ratio, alveolar and septal edema). Notably, POV stabilized hemodynamics at lower doses than AVP. In addition, POV, but not AVP, reduced myocardial and pulmonary tissue concentrations of 3-nitrotyrosine, VEGF, and angiopoietin-2, thereby leading to an abolishment of cumulative fluid accumulation (POV, 9 ± 15 ml/kg vs. AVP, 110 ± 13 ml/kg vs. control, 213 ± 16 ml/kg; P < 0.001 each) and an attenuated cardiopulmonary dysfunction (left ventricular stroke work index, PaO(2)-to-FiO(2) ratio) versus control animals. Highly selective V(1a)-agonism appears to be superior to unselective vasopressin analogs for the treatment of sepsis-induced vascular dysfunction.

Translational research in sepsis - an ultimate challenge?

In the era of evidence-based medicine, large, randomized, controlled, multicenter studies represent the "summit of evidence". In contrast to specialties like cardiology, the majority of randomized, controlled trials in critical care medicine, however, have failed to demonstrate a survival benefit; notably, despite encouraging results from experimental and phase-II clinical studies. The difficulty in translating our theoretical knowledge into successful multicenter randomized, controlled trials and subsequent treatment recommendations may represent one reason, why the mortality of septic shock still averages between 40-60%, although our knowledge about the underlying pathophysiology has considerably increased and international guidelines have widely been implemented. The present article elucidates some of the difficulties in translating research from bench to bedside.

Effects of vasopressinergic receptor agonists on sublingual microcirculation in norepinephrine-dependent septic shock

INTRODUCTION

The present study was designed to determine the effects of continuously infused norepinephrine (NE) plus (1) terlipressin (TP) or (2) arginine vasopressin (AVP) or (3) placebo on sublingual microcirculation in septic shock patients. The primary study end point was a difference of ≥ 20% in the microvascular flow index of small vessels among groups.

METHODS

The design of the study was a prospective, randomized, double-blind clinical trial. NE was titrated to maintain mean arterial pressure (MAP) between 65 and 75 mmHg after establishment of normovolemia in 60 septic shock patients. Thereafter patients (n = 20 per group) were randomized to receive continuous infusions of either TP (1 μg/kg/hour), AVP (0.04 U/minute) or placebo (isotonic saline). In all groups, open-label NE was adjusted to maintain MAP within threshold values if needed. The sublingual microcirculatory blood flow of small vessels was assessed by sidestream dark-field imaging. All measurements, including data from right heart catheterization and norepinephrine requirements, were obtained at baseline and 6 hours after randomization.

RESULTS

TP and AVP decreased NE requirements at the end of the 6-hour study period. The data are medians (25th and 75th interquartile ranges (IQRs)): 0.57 μg/kg/minute (0.29 to 1.04) vs. 0.16 μg/kg/minute (0.03 to 0.37) for TP and 0.40 μg/kg/minute (0.20 to 1.05) vs. 0.23 μg/kg/minute (0.03 to 0.77) for AVP, with statistical significance of P < 0.05 vs. baseline and vs. placebo. There were no differences in sublingual microcirculatory variables, systemic hemodynamics, oxygen transport and acid-base homeostasis among the three study groups during the entire observation period. The proportions of perfused vessels increased in relation to baseline within all study groups, and there were no significant differences between groups. The specific data were as follows (median (IQR)): 9.7% (2.6 to 19.8) for TP, 8.9% (0.0 to 17.8) for AVP, and 6.9% (3.5 to 10.1) for placebo (P < 0.05 vs. baseline for each comparison), as well as perfused vessel density 18.6% (8.6 to 36.9) for TP, 20.2% (-3.0 to 37.2) for AVP, and 11.4% (-3.0 to 19.4) for placebo (P < 0.05 vs. baseline for each comparison).

CONCLUSIONS

The present study suggests that to achieve a MAP of 65 to 75 mmHg in septic patients treated with NE, the addition of continuously infused low-dose TP or AVP does not affect sublingual microcirculatory blood flow. In addition, our results suggest that microcirculatory flow abnormalities are mainly related to other factors (for example, volume status, timing, hemodynamics and progression of the disease) rather than to the vasopressor per se.

TRIAL REGISTRATION

ClinicalTrial.gov NCT00995839.

Bench-to-bedside review: Vasopressin in the management of septic shock

This review of vasopressin in septic shock differs from previous reviews by providing more information on the physiology and pathophysiology of vasopressin and vasopressin receptors, particularly because of recent interest in more specific AVPR1a agonists and new information from the Vasopressin and Septic Shock Trial (VASST), a randomized trial of vasopressin versus norepinephrine in septic shock. Relevant literature regarding vasopressin and other AVPR1a agonists was reviewed and synthesized. Vasopressin, a key stress hormone in response to hypotension, stimulates a family of receptors: AVPR1a, AVPR1b, AVPR2, oxytocin receptors and purinergic receptors. Rationales for use of vasopressin in septic shock are as follows: first, a deficiency of vasopressin in septic shock; second, low-dose vasopressin infusion improves blood pressure, decreases requirements for norepinephrine and improves renal function; and third, a recent randomized, controlled, concealed trial of vasopressin versus norepinephrine (VASST) suggests low-dose vasopressin may decrease mortality of less severe septic shock. Previous clinical studies of vasopressin in septic shock were small or not controlled. There was no difference in 28-day mortality between vasopressin-treated versus norepinephrine-treated patients (35% versus 39%, respectively) in VASST. There was potential benefit in the prospectively defined stratum of patients with less severe septic shock (5 to 14 μg/minute norepinephrine at randomization): vasopressin may have lowered mortality compared with norepinephrine (26% versus 36%, respectively, P = 0.04 within stratum). The result was robust: vasopressin also decreased mortality (compared with norepinephrine) if less severe septic shock was defined by the lowest quartile of arterial lactate or by use of one (versus more than one) vasopressor at baseline. Other investigators found greater hemodynamic effects of higher dose of vasopressin (0.06 units/minute) but also unique adverse effects (elevated liver enzymes and serum bilirubin). Use of higher dose vasopressin requires further evaluation of efficacy and safety. There are very few studies of interactions of therapies in critical care - or septic shock - and effects on mortality. Therefore, the interaction of vasopressin infusion, corticosteroid treatment and mortality of septic shock was evaluated in VASST. Low-dose vasopressin infusion plus corticosteroids significantly decreased 28-day mortality compared with corticosteroids plus norepinephrine (44% versus 35%, respectively, P = 0.03; P = 0.008 interaction statistic). Prospective randomized controlled trials would be necessary to confirm this interesting interaction. In conclusion, low-dose vasopressin may be effective in patients who have less severe septic shock already receiving norepinephrine (such as patients with modest norepinephrine infusion (5 to 15 μg/minute) or low serum lactate levels). The interaction of vasopressin infusion and corticosteroid treatment in septic shock requires further study.

Cardiopulmonary effects of low-dose arginine vasopressin in ovine acute lung injury

OBJECTIVE

To elucidate the effects of low-dose arginine vasopressin on cardiopulmonary functions and nitrosative stress using an established model of acute lung injury.

DESIGN

Prospective, randomized, controlled laboratory experiment.

SETTING

Investigational intensive care unit.

SUBJECTS

Eighteen chronically instrumented sheep.

INTERVENTIONS

Sheep were randomly assigned to a sham group without injury or treatment, an injury group without treatment (40% total body surface area third-degree burn and 48 breaths of cold cotton smoke), or an injured group treated with arginine vasopressin (0.02 IU·min⁻¹) from 1 hr after injury until the end of the 24-hr study period (each n = 6). All sheep were mechanically ventilated and fluid resuscitated using an established protocol.

MEASUREMENTS AND MAIN RESULTS

There were no differences among groups at baseline. The injury was characterized by a severe deterioration of cardiopulmonary function (left ventricular stroke work indexes and Pao2/Fio2 ratio; p < .01 each vs. sham). Compared with controls, arginine vasopressin infusion improved myocardial function, as suggested by higher stroke volume indexes and left ventricular stroke work indexes (18-24 hrs and 6-24 hrs, respectively; p < .05 each). In addition to an improved gas exchange (higher Pao2/Fio2 ratios from 6 to 24 hrs, p < .01 each), pulmonary edema (bloodless wet-to-dry-weight ratio; p = .018), bronchial obstruction (p = .01), and pulmonary shunt fraction (12-24 hrs; p ≤ .001 each) were attenuated in arginine vasopressin-treated animals compared with controls. These changes occurred along with reduced nitrosative stress, as indicated by lower plasma levels of nitrate/nitrite (12-24 hrs, p < .01 each), as well as lower myocardial and pulmonary tissue concentrations of 3-nitrotyrosine (p = .041 and p = .042 vs. controls, respectively). At 24 hrs, pulmonary 3-nitrotyrosine concentrations were negatively correlated with Pao2/Fio2 ratio (r = -.882; p < .001) and myocardial 3-nitrotyrosine content with stroke volume indexes (r = -.701; p = .004).

CONCLUSIONS

Low-dose arginine vasopressin reduced nitrosative stress and improved cardiopulmonary functions in sheep with acute lung injury secondary to combined burn and smoke inhalation injury.

Effects of two different dosing regimens of terlipressin on organ functions in ovine endotoxemia

OBJECTIVE AND DESIGN

To test the hypothesis that a continuous infusion of the vasopressin analog terlipressin is associated with less organ dysfunction as compared to intermittent bolus infusion in an ovine sepsis model.

SUBJECTS

Twenty-seven adult female sheep.

TREATMENT

All sheep were subjected to a Salmonella typhosa endotoxin infusion (10 ng/kg/min). After 16 h of endotoxemia, the surviving animals (n = 24) were randomized to (1) an untreated control group, (2) a continuous terlipressin group (2 mg/24 h), or (3) a terlipressin bolus group (1 mg/6 h).

METHODS

Hemodynamic variables were measured and blood was withdrawn at specific time points for the assessment of organ functions.

RESULTS

Continuous terlipressin infusion was associated with improved surrogate parameters of myocardial, renal, and hepatic function as compared with terlipressin bolus infusion. Reduced vascular hyperpermeability was evidenced by an attenuated decrease in plasma protein concentrations in sheep treated with continuous terlipressin infusion as compared to bolus injection or no treatment.

CONCLUSIONS

Continuous infusion of low-dose terlipressin preserved several surrogate parameters of organ function better than intermittent bolus injections in sheep with systemic inflammation.

Year in review 2009: Critical Care--shock

The research papers on shock that have been published in Critical Care throughout 2009 are related to four major subjects: first, alterations of heart function and, second, the role of the sympathetic central nervous system during sepsis; third, the impact of hemodynamic support using vasopressin or its synthetic analog terlipressin, and different types of fluid resuscitation; as well as, fourth, experimental studies on the treatment of acute respiratory distress syndrome. The present review summarizes the key results of these studies together with a brief discussion in the context of the relevant scientific and clinical background published both in this and other journals.

Role of selective V2-receptor-antagonism in septic shock: a randomized, controlled, experimental study

Introduction

V₂-receptor (V₂R) stimulation potentially aggravates sepsis-induced vasodilation, fluid accumulation and microvascular thrombosis. Therefore, the present study was performed to determine the effects of a first-line therapy with the selective V₂R-antagonist (Propionyl₁-D-Tyr(Et)₂-Val₄-Abu₆-Arg_8,9)-Vasopressin on cardiopulmonary hemodynamics and organ function vs. the mixed V_1aR/V₂R-agonist arginine vasopressin (AVP) or placebo in an established ovine model of septic shock.

Methods

After the onset of septic shock, chronically instrumented sheep were randomly assigned to receive first-line treatment with the selective V₂R-antagonist (1 μg/kg per hour), AVP (0.05 μg/kg per hour), or normal saline (placebo, each n = 7). In all groups, open-label norepinephrine was additionally titrated up to 1 μg/kg per minute to maintain mean arterial pressure at 70 ± 5 mmHg, if necessary.

Results

Compared to AVP- and placebo-treated animals, the selective V₂R-antagonist stabilized cardiopulmonary hemodynamics (mean arterial and pulmonary artery pressure, cardiac index) as effectively and increased intravascular volume as suggested by higher cardiac filling pressures. Furthermore, left ventricular stroke work index was higher in the V₂R-antagonist group than in the AVP group. Notably, metabolic (pH, base excess, lactate concentrations), liver (transaminases, bilirubin) and renal (creatinine and blood urea nitrogen plasma levels, urinary output, creatinine clearance) dysfunctions were attenuated by the V₂R-antagonist when compared with AVP and placebo. The onset of septic shock was associated with an increase in AVP plasma levels as compared to baseline in all groups. Whereas AVP plasma levels remained constant in the placebo group, infusion of AVP increased AVP plasma levels up to 149 ± 21 pg/mL. Notably, treatment with the selective V₂R-antagonist led to a significant decrease of AVP plasma levels as compared to shock time (P < 0.001) and to both other groups (P < 0.05 vs. placebo; P < 0.001 vs. AVP). Immunohistochemical analyses of lung tissue revealed higher hemeoxygenase-1 (vs. placebo) and lower 3-nitrotyrosine concentrations (vs. AVP) in the V₂R-antagonist group. In addition, the selective V₂R-antagonist slightly prolonged survival (14 ± 1 hour) when compared to AVP (11 ± 1 hour, P = 0.007) and placebo (11 ± 1 hour, P = 0.025).

Conclusions

Selective V₂R-antagonism may represent an innovative therapeutic approach to attenuate multiple organ dysfunction in early septic shock.

Effects of combined arginine vasopressin and levosimendan on organ function in ovine septic shock

OBJECTIVE

To compare the effects of a first-line therapy of combined arginine vasopressin, levosimendan, and norepinephrine with arginine vasopressin + norepinephrine or norepinephrine alone in ovine septic shock.

DESIGN

Prospective, randomized, controlled laboratory experiment.

SETTING

University animal research facility.

SUBJECTS

Twenty-one chronically instrumented sheep.

INTERVENTIONS

After the onset of fecal peritonitis-induced septic shock (mean arterial pressure <60 mm Hg), sheep were randomly assigned to receive first-line treatment with arginine vasopressin (0.5 mU·kg·min), combined arginine vasopressin (0.5 mU·kg·min) and levosimendan (0.2 μg·kg·min), or normal saline (each n = 7) for 24 hrs. In all groups, open-label norepinephrine was additionally titrated to maintain mean arterial pressure at 70 ± 5 mm Hg, if necessary.

MEASUREMENTS AND MAIN RESULTS

Arginine vasopressin + levosimendan + norepinephrine improved left ventricular contractility (higher stroke work indices at similar or lower preload) and pulmonary function (Pao2/Fio2 ratio) when compared with the other groups (p < .05 each). Both nonadrenergic treatment strategies reduced open-label norepinephrine doses. However, only arginine vasopressin + levosimendan + norepinephrine limited fluid requirements and positive fluid balance vs. both other groups (p < .05 each). In addition, arginine vasopressin + levosimendan + norepinephrine increased mixed venous oxygen saturation as compared with arginine vasopressin + norepinephrine. Histologic tissue analyses and pulmonary hemeoxygenase-1 activity revealed no differences among groups. Notably, arginine vasopressin + levosimendan + norepinephrine therapy reduced pulmonary 3-nitrotyrosine levels (p = .028 vs. control animals) as well as urinary protein/creatinine ratio (p < .05 each) and slightly prolonged survival when compared with both other groups (4 hrs vs. arginine vasopressin + norepinephrine: p = .013; 7 hrs vs. norepinephrine alone: p = .003).

CONCLUSIONS

First-line cardiovascular support with combined arginine vasopressin and levosimendan supplemented with norepinephrine improves myocardial, vascular, pulmonary, and renal function as compared with arginine vasopressin + norepinephrine in septic shock.

Continuous Terlipressin Infusion as Rescue Treatment in a Case Series of Children with Refractory Septic Shock

Background:

Despite intensive therapy, refractory pediatric septic shock has a high rate of morbidity and mortality. Additional treatments are needed to improve outcomes in such cases.

Objective:

To report the clinical effects of continuous terlipressin infusion as rescue treatment for children with septic shock refractory to high catecholamine doses.

Methods:

Sixteen episodes of catecholamine-resistant septic shock were recorded in 15 children (aged from newborn to 15 years) who received compassionate rescue treatment with terlipressin at 6 pediatric intensive care units. Terlipressin treatment consisted of a loading dose (20 μg/kg) followed by continuous infusion at a rate of 4–20 μg/kg/h. Terlipressin was titrated at increases of 1 μg/kg/h to maintain mean arterial pressure (MAP) in normal range for age and to reduce catecholamine dosage. The main outcome was survival of the episode. Secondary outcomes included hemodynamic effects, ischemia, and terlipressin-related adverse events.

Results:

Terlipressin increased median MAP from 48 (range 42–63) to 68 (45–115) mm Hg 30 minutes after terlipressin administration (p < 0.01). MAP was subsequently sustained, which allowed for the reduction of norepinephrine infusion from 2 μg/kg/min (1–4) at baseline to 1.5 μg/kg/min (0.4–4) at 1 hour, 1.3 μg/kg/min (0–8) at 4 hours, 1 μg/kg/min (0–2) at 12 hours, 0.45 μg/kg/min (0–1.4) at 24 hours, and 0 μg/kg/min (0–0.6) at 48 hours (p < 0.05 vs baseline in all cases). In 8 (50%) of the 16 septic shock episodes the patients survived, 7 (44%) without sequelae. One patient survived with sequelae (minor amputation and mild cutaneous ischemia). Eight patients had signs of ischemia at admission; terlipressin induced reversible ischemia in another 4 patients. Meningococcal infection, prior ischemia, and MAP were risk factors for mortality.

Conclusions:

Continuous terlipressin infusion may improve hemodynamics and survival in some children with refractory septic shock. Terlipressin could contribute to tissue ischemia.

Terlipressin: a promising vasoactive agent in hemodynamic support of septic shock

BACKGROUND

At present, terlipressin is predominantly used for the management of bleeding gastric and esophageal varices, as well as hepato-renal syndrome secondary to liver cirrhosis. Owing to its high and relatively selective affinity to vascular V1 receptors, terlipressin is also increasingly used as an adjunct vasopressor agent in the management of vasodilatory hyperdynamic septic shock.

OBJECTIVE

This review article aims to summarize the available knowledge related to hemodynamic support with terlipressin in septic shock.

METHODS

For literature search, PubMed and specific keywords from the MeSH Database were used.

RESULTS/CONCLUSIONS

Terlipressin represents an effective pressor agent in patients with catecholamine-unresponsive septic shock. However, caution should be exercised, as terlipressin may contribute dose-dependently to vasoconstriction and a reflectory decrease in cardiac output. Additional studies are needed to clarify: i) the optimal time of therapy institution; ii) the efficacy and the dosages of continuous infusion versus bolus administration; and iii) the safety and efficacy of this compound in comparison with other nonspecific vasopressinergic drugs, such as arginine vasopressin. Whether or not terlipressin may improve the outcome of septic shock patients compared with standard therapy with catecholamines remains to be determined.

Arginine vasopressin in septic shock: supplement or substitute for norepinephrine?

In the current issue of Critical Care, Simon and coworkers investigated the effects of first-line arginine vasopressin (AVP) on organ function and systemic metabolism compared with norepinephrine in a pig model of fecal peritonitis. AVP was titrated according to the mean arterial pressure suggesting a vasopressor rather than a hormone replacement therapy. The study provides some evidence for the safety of this therapeutic approach. It needs to be determined whether AVP is most beneficial as a constant low-dose infusion to supplement norepinephrine or in higher doses than currently recommended to substitute norepinephrine. In addition, future studies are warranted to evaluate whether a first-line therapy of AVP is superior to a last-resort administration.

Continuous terlipressin versus vasopressin infusion in septic shock (TERLIVAP): a randomized, controlled pilot study

Introduction

Recent clinical data suggest that early administration of vasopressin analogues may be advantageous compared to a last resort therapy. However, it is still unknown whether vasopressin and terlipressin are equally effective for hemodynamic support in septic shock. The aim of the present prospective, randomized, controlled pilot trial study was, therefore, to compare the impact of continuous infusions of either vasopressin or terlipressin, when given as first-line therapy in septic shock patients, on open-label norepinephrine requirements.

Methods

We enrolled septic shock patients (n = 45) with a mean arterial pressure below 65 mmHg despite adequate volume resuscitation. Patients were randomized to receive continuous infusions of either terlipressin (1.3 μg·kg^-1·h^-1), vasopressin (.03 U·min^-1) or norepinephrine (15 μg·min^-1; n = 15 per group). In all groups, open-label norepinephrine was added to achieve a mean arterial pressure between 65 and 75 mmHg, if necessary. Data from right heart and thermo-dye dilution catheterization, gastric tonometry, as well as laboratory variables of organ function were obtained at baseline, 12, 24, 36 and 48 hours after randomization. Differences within and between groups were analyzed using a two-way ANOVA for repeated measurements with group and time as factors. Time-independent variables were compared with one-way ANOVA.

Results

There were no differences among groups in terms of systemic and regional hemodynamics. Compared with infusion of .03 U of vasopressin or 15 μg·min^-1 of norepinephrine, 1.3 μg·kg^-1·h^-1 of terlipressin allowed a marked reduction in catecholamine requirements (0.8 ± 1.3 and 1.2 ± 1.4 vs. 0.2 ± 0.4 μg·kg^-1·min^-1 at 48 hours; each P < 0.05) and was associated with less rebound hypotension (P < 0.05). At the end of the 48-hour intervention period, bilirubin concentrations were higher in the vasopressin and norepinephrine groups as compared with the terlipressin group (2.3 ± 2.8 and 2.8 ± 2.5 vs. 0.9 ± 0.3 mg·dL^-1; each P < 0.05). A time-dependent decrease in platelet count was only observed in the terlipressin group (P < 0.001 48 hours vs. BL).

Conclusions

The present study provides evidence that continuous infusion of low-dose terlipressin – when given as first-line vasopressor agent in septic shock – is effective in reversing sepsis-induced arterial hypotension and in reducing norepinephrine requirements.

Trial registration

ClinicalTrial.gov NCT00481572.

Comparison of cardiac, hepatic, and renal effects of arginine vasopressin and noradrenaline during porcine fecal peritonitis: a randomized controlled trial

Introduction

Infusing arginine vasopressin (AVP) in vasodilatory shock usually decreases cardiac output and thus systemic oxygen transport. It is still a matter of debate whether this vasoconstriction impedes visceral organ blood flow and thereby causes organ dysfunction and injury. Therefore, we tested the hypothesis whether low-dose AVP is safe with respect to liver, kidney, and heart function and organ injury during resuscitated septic shock.

Methods

After intraperitoneal inoculation of autologous feces, 24 anesthetized, mechanically ventilated, and instrumented pigs were randomly assigned to noradrenaline alone (increments of 0.05 μg/kg/min until maximal heart rate of 160 beats/min; n = 12) or AVP (1 to 5 ng/kg/min; supplemented by noradrenaline if the maximal AVP dosage failed to maintain mean blood pressure; n = 12) to treat sepsis-associated hypotension. Parameters of systemic and regional hemodynamics (ultrasound flow probes on the portal vein and hepatic artery), oxygen transport, metabolism (endogenous glucose production and whole body glucose oxidation derived from blood glucose isotope and expiratory ¹³CO₂/¹²CO₂ enrichment during 1,2,3,4,5,6-¹³C₆-glucose infusion), visceral organ function (blood transaminase activities, bilirubin and creatinine concentrations, creatinine clearance, fractional Na⁺ excretion), nitric oxide (exhaled NO and blood nitrate + nitrite levels) and cytokine production (interleukin-6 and tumor necrosis factor-α blood levels), and myocardial function (left ventricular dp/dt_max and dp/dt_min) and injury (troponin I blood levels) were measured before and 12, 18, and 24 hours after peritonitis induction. Immediate post mortem liver and kidney biopsies were analysed for histomorphology (hematoxylin eosin staining) and apoptosis (TUNEL staining).

Results

AVP decreased heart rate and cardiac output without otherwise affecting heart function and significantly decreased troponin I blood levels. AVP increased the rate of direct, aerobic glucose oxidation and reduced hyperlactatemia, which coincided with less severe kidney dysfunction and liver injury, attenuated systemic inflammation, and decreased kidney tubular apoptosis.

Conclusions

During well-resuscitated septic shock low-dose AVP appears to be safe with respect to myocardial function and heart injury and reduces kidney and liver damage. It remains to be elucidated whether this is due to the treatment per se and/or to the decreased exogenous catecholamine requirements.

Role of arginine vasopressin and terlipressin as first-line vasopressor agents in fulminant ovine septic shock

PURPOSE

To compare the effects of first-line therapy with low-dose arginine vasopressin (AVP) or terlipressin (TP) on mesenteric blood flow, plasma AVP levels, organ function and mortality in ovine septic shock.

METHODS

Twenty-four adult ewes were anesthetized and instrumented for chronic hemodynamic monitoring. A flow-probe was placed around the superior mesenteric artery, and feces were extracted from the cecum. Following baseline measurements, feces were injected into the peritoneal cavity. When mean arterial pressure (MAP) decreased to less than 60 mmHg, animals were randomly assigned to receive AVP (0.5 mU kg(-1) min(-1)), TP (1 microg kg(-1) h(-1)) or saline (n = 8 each). A norepinephrine infusion was titrated to maintain MAP at 70 +/- 5 mmHg in all groups.

RESULTS

Cardiovascular pressures, cardiac output, mesenteric blood flow, and lung tissue concentrations of 3-nitrotyrosine and hemoxygenase-1 were similar among groups throughout the study period. TP infusion resulted in lower plasma AVP concentrations, reduced positive net fluid balance, increased central venous oxygen saturation and slightly prolonged survival compared to control and AVP-treated animals. However, TP treatment was associated with higher liver transaminases and lactate dehydrogenase versus control animals after 12 h.

CONCLUSIONS

This study provides evidence that the effects of low-dose TP differ from those of AVP, not only as TP has a longer half life, but also because of different mechanisms of action. Although low-dose TP infusion may be superior to sole norepinephrine or AVP therapy in septic shock, the safety of this therapeutic approach should be determined in more detail.