Endogenous and exogenous vasopressin in shock

Copeptin concentration following cardiac surgery as a prognostic marker of postoperative acute kidney injury: a prospective cohort study

Background

Copeptin, the C-terminal portion of the arginine vasopressin precursor, is a novel candidate biomarker. This study investigated the prognostic value of copeptin levels following cardiac surgery for the occurrence of postoperative acute kidney injury.

Methods

We studied 23 patients who underwent cardiac surgery between January 2018 and December 2019. The primary endpoint was postoperative acute kidney injury onset. Copeptin levels were measured before, right after, and daily for 7 days. The patients were divided into two groups according to the copeptin levels: low (values <43.7 pmol/L) and high (values ≥43.7 pmol/L). Correlations between copeptin levels and variables, such as central venous pressure, were assessed by bivariate analysis.

Results

The high copeptin group exhibited significantly higher levels of arginine vasopressin and cortisol following surgery, compared to those of the low copeptin group. The copeptin concentration following surgery was correlated to central venous pressure (P=0.03) and norepinephrine administered dose (P=0.008). Also, the copeptin levels right after surgery robustly predicted the onset of postoperative acute kidney injury (area under the receiver operating characteristic curve of 0.83, P=0.004).

Conclusions

Elevated copeptin levels in patients following cardiac surgery predicted postoperative acute kidney injury development. Therefore, the copeptin concentration after surgery could represent a promising clinical biomarker of the postoperative cardiac outcome.

Effect of Low-Dose Supplementation of Arginine Vasopressin on Need for Blood Product Transfusions in Patients With Trauma and Hemorrhagic Shock: A Randomized Clinical Trial

Importance

Current therapies for traumatic blood loss focus on hemorrhage control and blood volume replacement. Severe hemorrhagic shock, however, is associated with a state of arginine vasopressin (AVP) deficiency, and supplementation of this hormone may decrease the need for blood products in resuscitation.

Objective

To determine whether low-dose supplementation of AVP in patients with trauma (hereinafter referred to as trauma patients) and with hemorrhagic shock decreases their need for transfused blood products during resuscitation.

Design, Setting, and Participants

This randomized, double-blind placebo-controlled clinical trial included adult trauma patients (aged 18-65 years) who received at least 6 U of any blood product within 12 hours of injury at a single urban level 1 trauma center from May 1, 2013, through May 31, 2017. Exclusion criteria consisted of prehospital cardiopulmonary resuscitation, emergency department thoracotomy, corticosteroid use, chronic renal insufficiency, coronary artery disease, traumatic brain injury requiring any neurosurgical intervention, pregnancy, prisoner status, or AVP administration before enrollment. Data were analyzed from May 1, 2013, through May 31, 2017, using intention to treat and per protocol.

Interventions

After administration of an AVP bolus (4 U) or placebo, participants received AVP (≤0.04 U/min) or placebo for 48 hours to maintain a mean arterial blood pressure of at least 65 mm Hg.

Main Outcomes

The primary outcome was total volume of blood product transfused. Secondary end points included total volume of crystalloid transfused, vasopressor requirements, secondary complications, and 30-day mortality.

Results

One hundred patients underwent randomization (49 to the AVP group and 51 to the placebo group). Patients were primarily young (median age, 27 years [interquartile range {IQR}, 22-25 years]) and male (n = 93) with penetrating trauma (n = 79). Cohort characteristics before randomization were well balanced. At 48 hours, patients who received AVP required significantly less blood products (median, 1.4 [IQR, 0.5-2.6] vs 2.9 [IQR, 1.1-4.8] L; P = .01) but did not differ in requirements for crystalloids (median, 9.9 [IQR, 7.9-13.0] vs 11.0 [8.9-15.0] L; P = .22) or vasopressors (median, 400 [IQR, 0-5900] vs 1400 [IQR, 200-7600] equivalent units; P = .22). Although the groups had similar rates of mortality (6 of 49 [12%] vs 6 of 51 [12%]; P = .94) and total complications (24 of 44 [55%] vs 30 of 47 [64%]; P = .37), the AVP group had less deep venous thrombosis (5 of 44 [11%] vs 16 of 47 [34%]; P = .02).

Conclusions and Relevance

Low-dose AVP during the resuscitation of trauma patients in hemorrhagic shock decreases blood product requirements. Additional research is necessary to determine whether including AVP improves morbidity or mortality.

Trial Registration

ClinicalTrials.gov identifier: NCT01611935.

Supplemental arginine vasopressin during the resuscitation of severe hemorrhagic shock preserves renal mitochondrial function

Arginine vasopressin (AVP), a hormone secreted by the posterior pituitary, plays a vital role in maintaining vasomotor tone during acute blood loss. We hypothesized that decompensated hemorrhagic shock is associated with decreased AVP stores and supplementation during resuscitation would improve both blood pressure and renal function. Using a decompensated hemorrhagic shock model, male Long-Evans rats were bled to mean arterial blood pressure (MAP) of 40mmHg and maintained until the MAP could not be sustained without fluid. Once 40% of the shed volume was returned in lactated Ringer’s (Severe Shock), animals were resuscitated over 60 minutes with 4x the shed volume in lactated Ringer’s (LR) or the same fluids with AVP (0.5 units/kg+ 0.03 units/kg/min). Animals (n = 6-9/group) were sacrificed before hemorrhage (Sham), at Severe Shock, following resuscitation (60R, 60R with AVP) or 18 hours post-resuscitation (18hr, 18hr with AVP). Blood samples were taken to measure AVP levels and renal function. Pituitaries were harvested and assayed for AVP. Kidney samples were taken to assess mitochondrial function, histology, and oxidative damage. Baseline pituitary AVP stores (30,364 ± 5311 pg/mg) decreased with severe shock and were significantly depressed post-resuscitation (13,910 ± 3016 pg/ml. p<0.05) and at 18hr (15,592 ±1169 pg/ml, p<0.05). Resuscitation with LR+AVP led to higher serum AVP levels at 60R (31±8 vs 79±12; p<0.01) with an improved MAP both at 60R (125±3 vs 77±7mmHg; p<0.01) and 18hr (82±6 vs 69±5mmHg;p<0.05). AVP supplementation preserved complex I respiratory capacity at 60R and both complex I and II function at 18hr (p<0.05). AVP was also associated with decreased reactive oxygen species at 60R (856±67 vs 622±48F RFU) and significantly decreased oxidative damage as measured by mitochondrial lipid peroxidation (0.9±0.1 vs 1.7±0.1 fold change, p<0.01) and nitrosylation (0.9±0.1 vs 1.4±0.2 fold change, p<0.05). With AVP, renal damage was mitigated at 60R and histologic architecture was conserved at 18 hours. In conclusion, pituitary and serum AVP levels decrease during severe hemorrhage and may contribute to the development of decompensated hemorrhagic shock. Supplementing exogenous AVP during resuscitation improves blood pressure, preserves renal mitochondrial function, and mitigates acute kidney injury.

The role of vasopressin and the vasopressin type V1a receptor agonist selepressin in septic shock

Septic shock remains one of the major causes of morbidity and mortality in the critically ill. Despite early goal therapy and administration of cathecholaminergic agents, up to 30% of patients succumb to the disease. In this manuscript, we first summarize the standard of care of patients with septic shock and current guidelines. We review the physiologic role of vasopressin and its role in septic shock management. We then review the most up-to-date evidence on the potential role of V1a receptor agonists such as Selepressin, in septic shock. Exciting new trials are being completed in order to elucidate the role of V1a receptor agonists as potential first-line vasopressor alternatives in the therapy of circulatory shock in septic patients.

The selective vasopressin type 1a receptor agonist selepressin (FE 202158) blocks vascular leak in ovine severe sepsis*

OBJECTIVE

To determine if the selective vasopressin type 1a receptor agonist selepressin (FE 202158) is as effective as the mixed vasopressin type 1a receptor/vasopressin V2 receptor agonist vasopressor hormone arginine vasopressin when used as a titrated first-line vasopressor therapy in an ovine model of Pseudomonas aeruginosa pneumonia-induced severe sepsis.

DESIGN

Prospective, randomized, controlled laboratory experiment.

SETTING

University animal research facility.

SUBJECTS

Forty-five chronically instrumented sheep.

INTERVENTIONS

Sheep were anesthetized, insufflated with cooled cotton smoke via tracheostomy, and P. aeruginosa were instilled into their airways. They were then placed on assisted ventilation, awakened, and resuscitated with lactated Ringer's solution titrated to maintain hematocrit ± 3% from baseline levels. If, despite fluid management, mean arterial pressure fell by more than 10 mm Hg from baseline level, an additional continuous IV infusion of arginine vasopressin or selepressin was titrated to raise and maintain mean arterial pressure within no less than 10 mm Hg from baseline level. Effects of combination treatment of selepressin with the selective vasopressin V2 receptor agonist desmopressin were similarly investigated.

MEASUREMENTS AND MAIN RESULTS

In septic sheep, MAP fell by ~30 mm Hg, systemic vascular resistance index decreased by ~50%, and ~7 L of fluid were retained over 24 hours; this fluid accumulation was partially reduced by arginine vasopressin and almost completely blocked by selepressin; and combined infusion of selepressin and desmopressin increased fluid accumulation to levels similar to arginine vasopressin treatment.

CONCLUSIONS

Resuscitation with the selective vasopressin type 1a receptor agonist selepressin blocked vascular leak more effectively than the mixed vasopressin type 1a receptor/vasopressin V2 receptor agonist arginine vasopressin because of its lack of agonist activity at the vasopressin V2 receptor.

Component reductions in oxygen delivery generate variable haemodynamic and stress hormone responses

BACKGROUND

In clinical practice, global oxygen delivery (DO2) is often considered as a whole; however pathological and adaptive responses after a decrease in individual constituents of the DO2 equation (cardiac output, haemoglobin, oxyhaemoglobin saturation) are likely to be diverse. We hypothesized that an equivalent decrease in DO2 after reductions in each separate component of the equation would result in different haemodynamic, tissue oxygenation, and stress hormonal responses.

METHODS

Anaesthetized, fluid-resuscitated male Wistar rats were subjected to circulatory, anaemic, or hypoxic hypoxia (by haemorrhage, isovolaemic haemodilution, and breathing a hypoxic gas mix, respectively), produced either rapidly over 5 min or graded over 30 min, to a targeted 50% decrease in global oxygen delivery. Sham-operated animals acted as controls. Measurements were made of haemodynamics, skeletal muscle tissue oxygen tension, blood gas analysis, and circulating stress hormone levels.

RESULTS

Whereas haemorrhage generated the largest decrease in cardiac output, and the greatest stress hormone response, haemodilution had the most marked effect on arterial pressure. In contrast, rapid hypoxaemia produced a minor impact on global haemodynamics yet induced the greatest decrease in regional oxygenation. A greater degree of hyperlactataemia was observed with graded insults compared with those administered rapidly.

CONCLUSIONS

Decreasing global oxygen delivery, achieved by targeted reductions in its separate components, induces varying circulatory, tissue oxygen tension, and stress hormone responses. We conclude that not all oxygen delivery is the same; this disparity should be emphasized in classical teaching and re-evaluated in patient management.

Vasopressin for the treatment of neonatal hypotension

Vasopressin (pitressin), also known as arginine vasopressin (AVP), is an antidiuretic hormone formed in the hypothalamus and secreted from the posterior pituitary gland. Various forms of exogenous vasopressin exist and have been used in neonates to treat conditions such as diabetes insipidus. Vasopressin has also been studied on a limited basis for use in the treatment of catecholamine-resistant hypotension in vasodilatory shock. Hypotension is a significant problem resulting in increased morbidity in preterm, septic, and postsurgical neonates. This article will discuss the role of vasopressin and its use as a therapeutic agent in the treatment of hypotension in the neonate.

New, potent, selective, and short-acting peptidic V1a receptor agonists

[Arg(8)]vasopressin (AVP) produces vasoconstriction via V(1a) receptor (V(1a)R)-mediated vascular smooth muscle cell contraction and is being used to increase blood pressure in septic shock, a form of vasodilatory hypotension. However, AVP also induces V(2) receptor (V(2)R)-mediated antidiuresis, vasodilation, and coagulation factor release, all deleterious in septic shock. The V(1a)R agonist terlipressin (H-Gly(3)[Lys(8)]VP) also lacks selectivity vs the V(2)R and has sizably longer duration of action than AVP, preventing rapid titration of its vasopressor effect in the clinic. We designed and synthesized new short acting V(1a)R selective analogues of general structure [Xaa(2),Ile(3),Yaa(4),Zaa(8)]VP. The most potent and selective compounds in in vitro functional assays (e.g., [Phe(2),Ile(3),Asn(Me(2))(4),Orn(8)]VP (31), [Phe(2),Ile(3),Asn((CH(2))(3)OH)(4),Orn(8)]VP (34), [Phe(2),Ile(3),Hgn(4),Orn(iPr)(8)]VP (45), [Phe(2),Ile(3),Asn(Et)(4),Dab(8)]VP (49), [Thi(2),Ile(3),Orn(iPr)(8)]VP (59), [Cha(2),Ile(3),Asn(4),Orn(iPr)(8)]VP (68)) were tested by intravenous bolus in rats for duration of vasopressive action. Analogues 31, 34, 45, and 49 were as short-acting as AVP. Compound 45, FE 202158, is currently undergoing clinical trials in septic shock.

Multiple alpha1-adrenergic receptor subtypes support synergistic stimulation of vasopressin and oxytocin release by ATP and phenylephrine

Simultaneous exposure of explants of the hypothalamo-neurohypophyseal system (HNS) to ATP and the α(1)-adrenergic receptor (α(1)-R) agonist, phenylephrine (ATP+PE) induces a synergistic stimulation of vasopressin and oxytocin (VP/OT) release that is sustained for hours. The current studies confirm that the synergism is dependent upon activation of α(1)-R by demonstrating that an α(1)-R antagonist prevents the response. The role of the α(1)A, B, and D-adrenergic receptor subtypes in the synergistic effect of ATP+PE on intracellular calcium ([Ca(2+)](i)) in supraoptic nucleus (SON) neurons and VP/OT release from neural lobe was evaluated. The increase in [Ca(2+)](i) induced by PE in SON predominantly reflects release from intracellular stores and is mediated by activation of the α(1)A adrenergic receptor subtype. The α(1)A subtype is also required for the sustained elevation in [Ca(2+)](i) induced by ATP+PE. In contrast, although synergistic stimulation of VP/OT release was eliminated by removal of PE and was blunted by benoxathian, an α(1)-R antagonist that is not subtype selective, no single α(1)-R subtype selective antagonist prevented sustained stimulation of VP/OT release by ATP+PE. Thus, sustained activation of α(1)-R is essential for the synergistic VP and OT response to ATP+PE, but multiple α(1)-R subtypes can support the response. Redundancy amongst the α(1)-R subunits in supporting this response is consistent with the predicted importance of the response for sustaining the elevated VP release required to prevent cardiovascular collapse during hemorrhage and sepsis.

Sustained stimulation of vasopressin and oxytocin release by ATP and phenylephrine requires recruitment of desensitization-resistant P2X purinergic receptors

Coexposure of hypothalamo-neurohypophyseal system explants to ATP and phenylephrine [PE; an alpha1-adrenergic receptor (alpha1-AR) agonist] induces an extended elevation in vasopressin and oxytocin (VP/OT) release. New evidence is presented that this extended response is mediated by recruitment of desensitization-resistant ionotropic purinergic receptor subtypes (P2X-Rs): 1) Antagonists of the P2X2/3 and P2X7-Rs truncated the sustained VP/OT release induced by ATP+PE but did not alter the transient response to ATP alone. 2) The P2X2/3 and P2X7-R antagonists did not alter either ATP or ATP+PE-induced increases in [Ca(2+)](i). 3) P2X2/3 and P2X7-R agonists failed to elevate [Ca(2+)](i), while ATP-gamma-S, an agonist for P2X2-Rs increased [Ca(2+)](i) and induced a transient increase in VP/OT release. 4) A P2Y1-R antagonist did not prevent initiation of the synergistic, sustained stimulation of VP/OT release by ATP+PE but did reduce its duration. Thus, the desensitization-resistant P2X2/3 and P2X7-R subtypes are required for the sustained, synergistic hormone response to ATP+PE, while P2X2-Rs are responsible for the initial activation of Ca(2+)-influx by ATP and ATP stimulation of VP/OT release. Immunohistochemistry, coimmunoprecipitation, and Western blot analysis confirmed the presence of P2X2 and P2X3, P2X2/3, and P2X7-R protein, respectively in SON. These findings support the hypothesis that concurrent activation of P2X2-R and alpha1-AR induces calcium-driven recruitment of P2X2/3 and 7-Rs, allowing sustained activation of a homeostatic circuit. Recruitment of these receptors may provide sustained release of VP during dehydration and may be important for preventing hemorrhagic and septic shock.

Vasopressin in pediatric shock and cardiac arrest

OBJECTIVE

To review the physiology and the published literature on the role of vasopressin in shock in children.

DATA SOURCE

We searched MEDLINE (1966-2007), EMBASE (1980-2007), and the Cochrane Library, using the terms vasopressin, terlipressin, and shock and synonyms or related terms for relevant studies in pediatrics. We searched the online ISRCTN-Current Controlled Trials registry for ongoing trials. We reviewed the reference lists of all identified studies and reviews as well as personal files to identify other published studies.

RESULTS

Beneficial effects have been reported in vasodilatory shock and asystolic cardiac arrest in adults. Solid evidence for vasopressin use in children is scant. Observational studies have reported an improvement in blood pressure and rapid weaning off catecholamines during administration of low-dose vasopressin. Dosing in children is extrapolated from adult studies.

CONCLUSIONS

Vasopressin offers promise in shock and cardiac arrest in children. However, in view of the limited experience with vasopressin, it should be used with caution. Results of a double-blind, randomized controlled trial in children with vasodilatory shock will be available soon.