Arginine vasopressin in the treatment of 50 patients with postcardiotomy vasodilatory shock

Factors associated with vasoplegic shock in the postoperative period of cardiac surgery and influence on morbidity and mortality of the use of arginine vasopressin as rescue therapy

OBJECTIVES

Analyzing associated factors with vasoplegic shock in the postoperative period of Cardiac Surgery. Analyzing the influence of vasopressin as rescue therapy to first-line treatment with norepinephrine.

DESIGN

Cohort, prospective and observational study.

SETTING

Main hospital Postoperative Cardiac ICU.

PATIENTS

Patients undergoing cardiac surgery with subsequent ICU admission from January 2021 to December 2022.

INTERVENTIONS

Record of presurgical, perioperative and ICU discharge clinical variables.

MAIN VARIABLES OF INTEREST

chronic treatment, presence of vasoplegic shock, need for vasopressin, cardiopulmonary bypass time, mortality.

RESULTS

773 patients met the inclusion criteria. The average age was 67.3, with predominance of males (65.7%). Post-CPB vasoplegia was documented in 94 patients (12.2%). In multivariate analysis, vasoplegia was associated with age, female sex, presurgical creatinine levels, cardiopulmonary bypass time, lactate level upon admission to the ICU, and need for prothrombin complex transfusion. Of the patients who developed vasoplegia, 18 (19%) required rescue vasopressin, associated with pre-surgical intake of ACEIs/ARBs, worse Euroscore score and longer cardiopulmonary bypass time. Refractory vasoplegia with vasopressin requirement was associated with increased morbidity and mortality.

CONCLUSIONS

Postcardiopulmonary bypass vasoplegia is associated with increased mortality and morbidity. Shortening cardiopulmonary bypass times and minimizing products blood transfusion could reduce its development. Removing ACEIs and ARBs prior to surgery could reduce the incidence of refractory vasoplegia requiring rescue with vasopressin. The first-line treatment is norepinephrine and rescue treatment with VSP is a good choice in refractory situations. The first-line treatment of this syndrome is norepinephrine, although rescue with vasopressin is a good complement in refractory situations.

Low-Dose vasopressin and renal perfusion in pediatric cardiac surgery

Background

Congenital heart surgeries are associated with post-bypass renal and cardiac dysfunctions. The use of low-dose vasopressin has been found to be beneficial in adult cardiac surgeries.

Objective

To assess the hemodynamic and renal effects of patients undergoing on-pump pediatric cardiac surgery under general anesthesia (GA) with low-dose vasopressin infusion.

Design

Prospective randomized controlled study.

Setting

Operation room and ICU, tertiary care teaching hospital.

Patients

Fifty-five pediatric cardiac patients undergoing repair for congenital heart diseases (CHD).

Interventions

Low-dose vasopressin infusion in the study group and placebo in the control group.

Measurements and Main Results

Renal near-infrared spectroscopy (NIRS), serum NGAL, and inflammatory mediators-IL6 and IL8 along with other renal and hemodynamic parameters in the perioperative period were recorded. Diastolic blood pressure (DBP) and cardiac index were significantly higher in the vasopressin group. Inflammatory markers were significantly high in the immediate postoperative period in all patients which later stabilized in the next 48 h but showed similar trends in both groups. Low-dose vasopressin infusion did not improve either renal perfusion or function. The duration of mechanical ventilation and length of hospital stay, the incidence of AKI development, and transfusion requirements were marginally lower in the vasopressin group, although not significant.

Conclusion

Low-dose vasopressin infusion improved hemodynamics and showed a decreased incidence of complications. However, it failed to show any benefit of renal function and overall outcome in pediatric cardiac surgery.

Vasopressor Therapy in the Intensive Care Unit

After fluid administration for vasodilatory shock, vasopressors are commonly infused. Causes of vasodilatory shock include septic shock, post-cardiovascular surgery, post-acute myocardial infarction, postsurgery, other causes of an intense systemic inflammatory response, and drug -associated anaphylaxis. Therapeutic vasopressors are hormones that activate receptors-adrenergic: α1, α2, β1, β2; angiotensin II: AG1, AG2; vasopressin: AVPR1a, AVPR1B, AVPR2; dopamine: DA1, DA2. Vasopressor choice and dose vary widely because of patient and physician practice heterogeneity. Vasopressor adverse effects are excessive vasoconstriction causing organ ischemia/infarction, hyperglycemia, hyperlactatemia, tachycardia, and tachyarrhythmias. To date, no randomized controlled trial (RCT) of vasopressors has shown a decreased 28-day mortality rate. There is a need for evidence regarding alternative vasopressors as first-line vasopressors. We emphasize that vasopressors should be administered simultaneously with fluid replacement to prevent and decrease duration of hypotension in shock with vasodilation. Norepinephrine is the first-choice vasopressor in septic and vasodilatory shock. Interventions that decrease norepinephrine dose (vasopressin, angiotensin II) have not decreased 28-day mortality significantly. In patients not responsive to norepinephrine, vasopressin or epinephrine may be added. Angiotensin II may be useful for rapid resuscitation of profoundly hypotensive patients. Inotropic agent(s) (e.g., dobutamine) may be needed if vasopressors decrease ventricular contractility. Dopamine has fallen to almost no-use recommendation because of adverse effects; angiotensin II is available clinically; there are potent vasopressors with scant literature (e.g., methylene blue); and the novel V1a agonist selepressin missed on its pivotal RCT primary outcome. In pediatric septic shock, vasopressors, epinephrine, and norepinephrine are recommended equally because there is no clear evidence that supports the use of one vasoactive agent. Dopamine is recommended when epinephrine or norepinephrine is not available. New strategies include perhaps patients will be started on several vasopressors with complementary mechanisms of action, patients may be selected for particular vasopressors according to predictive biomarkers, and novel vasopressors may emerge with fewer adverse effects.

Selepressin, a novel selective V1A receptor agonist: Effect on mesenteric flow and gastric mucosa perfusion in the endotoxemic rabbit

Intestinal or mesenteric ischemia generally leads to inflammation and injury, potentially developing hypoxia, causing cell death and tissue necrosis. This in turn can lead to sepsis and shock. Conversely, following shock, the intestinal tract is a main organ to experience ischemic/reperfusion injury. Increased intestinal cell-membrane permeability through mesenteric ischemia provoking bacterial translocation and gut-barrier injury can lead to sepsis and multi-organ failure. Hypotension induced by systemic vasodilation and vascular leak in systemic inflammatory response syndrome and sepsis is countered by immediate fluid resuscitation and vasopressor administration, primarily norepinephrine (NE), with possible arginine vasopressin (AVP) supplementation, an agonist of vasopressin V_1A and V₂ receptors. Selepressin is a selective V_1A-receptor agonist, avoiding potential V₂ receptor-associated adverse effects. Selepressin, non-selective AVP, and NE effects on mesenteric blood flow (MBF) and gastric mucosa perfusion (GMP) were compared in control rabbits and a lipopolysaccharide-induced, fluid-resuscitated rabbit endotoxemia model. AVP induced a pronounced decrease in MBF and GMP in non-endotoxemic and endotoxemic rabbits, whereas the reduction after selepressin treatment was significantly less for both indicators in the endotoxemic animals. By contrast, NE increased the MBF and did not affect GMP in both groups. Selepressin and AVP induced a pronounced dose-dependent increase in mesenteric vascular resistance in non-endotoxemic and endotoxemic rabbits, tending to be less in endotoxemic animals, whereas a minor increase in both groups was observed with NE. Therefore, in this safety study, the risk for mesenteric ischemia on selepressin treatment was not inferior to AVP, being less in endotoxemic than in non-endotoxemic animals.

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.

Vasopressor therapy in critically ill patients with shock

BACKGROUND

Vasopressors are administered to critically ill patients with vasodilatory shock not responsive to volume resuscitation, and less often in cardiogenic shock, and hypovolemic shock.

OBJECTIVES

The objectives are to review safety and efficacy of vasopressors, pathophysiology, agents that decrease vasopressor dose, predictive biomarkers, β1-blockers, and directions for research.

METHODS

The quality of evidence was evaluated using Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

RESULTS

Vasopressors bind adrenergic: α1, α2, β1, β2; vasopressin: AVPR1a, AVPR1B, AVPR2; angiotensin II: AG1, AG2; and dopamine: DA1, DA2 receptors inducing vasoconstriction. Vasopressor choice and dose vary because of patients and physician practice. Adverse effects include excessive vasoconstriction, organ ischemia, hyperglycemia, hyperlactatemia, tachycardia, and tachyarrhythmias. No randomized controlled trials of vasopressors showed a significant difference in 28-day mortality rate. Norepinephrine is the first-choice vasopressor in vasodilatory shock after adequate volume resuscitation. Some strategies that decrease norepinephrine dose (vasopressin, angiotensin II) have not decreased 28-day mortality while corticosteroids have decreased 28-day mortality significantly in some (two large trials) but not all trials. In norepinephrine-refractory patients, vasopressin or epinephrine may be added. A new vasopressor, angiotensin II, may be useful in profoundly hypotensive patients. Dobutamine may be added because vasopressors may decrease ventricular contractility. Dopamine is recommended only in bradycardic patients. There are potent vasopressors with limited evidence (e.g. methylene blue, metaraminol) and novel vasopressors in development (selepressin).

CONCLUSIONS

Norepinephrine is first choice followed by vasopressin or epinephrine. Angiotensin II and dopamine have limited indications. In future, predictive biomarkers may guide vasopressor selection and novel vasopressors may emerge.

Vasopressor therapy in critically ill patients with shock

BACKGROUND

Vasopressors are administered to critically ill patients with vasodilatory shock not responsive to volume resuscitation, and less often in cardiogenic shock, and hypovolemic shock.

OBJECTIVES

The objectives are to review safety and efficacy of vasopressors, pathophysiology, agents that decrease vasopressor dose, predictive biomarkers, β1-blockers, and directions for research.

METHODS

The quality of evidence was evaluated using Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

RESULTS

Vasopressors bind adrenergic: α1, α2, β1, β2; vasopressin: AVPR1a, AVPR1B, AVPR2; angiotensin II: AG1, AG2; and dopamine: DA1, DA2 receptors inducing vasoconstriction. Vasopressor choice and dose vary because of patients and physician practice. Adverse effects include excessive vasoconstriction, organ ischemia, hyperglycemia, hyperlactatemia, tachycardia, and tachyarrhythmias. No randomized controlled trials of vasopressors showed a significant difference in 28-day mortality rate. Norepinephrine is the first-choice vasopressor in vasodilatory shock after adequate volume resuscitation. Some strategies that decrease norepinephrine dose (vasopressin, angiotensin II) have not decreased 28-day mortality while corticosteroids have decreased 28-day mortality significantly in some (two large trials) but not all trials. In norepinephrine-refractory patients, vasopressin or epinephrine may be added. A new vasopressor, angiotensin II, may be useful in profoundly hypotensive patients. Dobutamine may be added because vasopressors may decrease ventricular contractility. Dopamine is recommended only in bradycardic patients. There are potent vasopressors with limited evidence (e.g. methylene blue, metaraminol) and novel vasopressors in development (selepressin).

CONCLUSIONS

Norepinephrine is first choice followed by vasopressin or epinephrine. Angiotensin II and dopamine have limited indications. In future, predictive biomarkers may guide vasopressor selection and novel vasopressors may emerge.

Vasoplegic syndrome in cardiac surgery: Definitions, pathophysiology, diagnostic approach and management

Vasoplegic syndrome is a state of vasopressor resistant systemic vasodilation in the presence of a normal cardiac output. Its definition, pathophysiology, risk factors, diagnosis and therapeutic approach will be reviewed in this paper. It occurs frequently during cardiac surgery and is associated with high morbidity and mortality. A search in the LILACS, MEDLINE, and GOOGLE SCHOLAR databases was conducted to find the most relevant papers during the last 18 years. Prompt identification and diagnosis of patients at risk must be undertaken in order to implement an optimal therapeutic approach. This latter includes early treatment with vasopressors with different mechanisms of action.

Pediatric Mechanical Circulatory Support

Over the past two decades clinicians and researchers have sought to bring mechanical circulatory support (MCS) to pediatric patients with heart failure. ECMO, IABPs, and VADs have all been used in infants and children as a bridge to myocardial recovery or as a bridge to transplant. However, until recently, a commitment by industry, government, and researchers towards the development of pediatric MCS has not been present, especially in the United States. Advancements in adult VAD design to smaller, quieter, and fully implantable pumps capable of complete outpatient support have sparked curiosity in the application of this technology to children. Also, the increasing success of palliating congenital heart disease is creating an ever-growing cohort of children and adolescents with heart failure. These changing demographics and technological advances have caused a refocus of attention. This is most clearly demonstrated by the international use of several established MCS pediatric and neonatal systems, by the FDA's increasing proclivity to allow the use of international pediatric VADs in the USA, and by the recent National Heart, Lung, and Blood Institute funding of several institutions to develop pediatric VADs. This review describes the different aspects of pediatric MCS including indications, the features of the various VADs, and their current application in children worldwide.

Anesthetic and Perioperative Considerations in Patients Undergoing Placement of Totally Implantable Replacement Hearts

The recent successful implantation of the AbioCor im plantable replacement heart at the Rudd Heart-Lung Institute, Jewish Hospital, Louisville, KY, has renewed clinical interest in the use of the mechanical replace ment heart as therapy for intractable heart failure. Al though the number of orthotopic heart transplants has plateaued in the past decade, the number of patients requiring transplantation continues to increase. This supply/demand discrepancy continues to be the main catalyst for the research and development of other therapies for the failing heart. This review addresses perioperative considerations, monitoring modalities, and perioperative therapeutic interventions that may help guide the cardiac anesthesiologist through the challenges presented by implantation of total replace ment hearts in end-stage cardiac patients.

Vasopressin: Applications in Clinical Practice

Arginine vasopressin is a peptide produced in the posterior pituitary whose primary physiologic role is fluid homeostasis. Recent investigations have demonstrated a therapeutic role for arginine vasopressin in adult cardiac arrest as well as adult and pediatric vasodilatory shock. We review the physiology of arginine vasopressin and examine the supporting data behind the developing clinical applications of this naturally produced peptide.

Vasodilatory Shock After Ventricular Assist Device Placement: A Bench to Bedside Review

With more than 2000 ventricular assist devices (VAD) placed annually in the United States, understanding postoperative management is important. One of the most common postoperative morbidities encountered with VAD implantation is vasodilatory shock. The mechanisms for this phenomenon are numerous and include cellular and hormonal aberrancies unique to the VAD recipient. Management of vasodilatory shock in VAD patients needs to be undertaken with an understanding of the side effects associated with each treatment, especially the effects on the right ventricle and pulmonary vasculature. This article focuses on the incidence, the pathogenesis, the consequences, and the management of vasodilatory shock in the postoperative VAD patient.

Endothelin and vasopressin influence splanchnic blood flow distribution during and after cardiopulmonary bypass

OBJECTIVE

Gastrointestinal blood flow can be compromised during and after cardiopulmonary bypass. Endothelin has been shown to be involved in the intestinal microcirculatory disturbance of sepsis. The aim of the present study was to analyze the involvement of the endothelin system on intestinal blood flow regulation during cardiopulmonary bypass and the effect of vasopressin given during cardiopulmonary bypass.

METHODS

A total of 24 pigs were studied in 4 groups (n = 6): group I, sham; group II, ischemia/reperfusion with 1 hour of superior mesenteric artery occlusion; group III, cardiopulmonary bypass for 1 hour; and group IV, 1 hour of cardiopulmonary bypass plus vasopressin administration, maintaining the baseline arterial pressure. All the pigs were reperfused for 90 minutes. During the experiment, the hemodynamics and jejunal microcirculation were measured continuously. The jejunal mucosal expression of endothelin-1 and its receptor subtypes A and B were determined using polymerase chain reaction.

RESULTS

During cardiopulmonary bypass, superior mesenteric artery flow was preserved but marked jejunal microvascular impairment occurred compared with baseline (mucosal capillary density, 192.2 ± 5.4 vs 150.8 ± 5.1 cm/cm(2); P = .005; tissue blood flow, 501.7 ± 39.3 vs 332.3 ± 27.9 AU; P = .025). The expression of endothelin-1 after cardiopulmonary bypass (3.2 ± 0.4 vs 12.2 ± 0.8 RQ, P = .006) and endothelin subtype A (0.7 ± 0.2 vs 2.4 ± 0.6 RQ; P = .01) was significantly increased compared to the sham group. Vasopressin administration during cardiopulmonary bypass led to normal capillary density (189.9 ± 3.9 vs 178.0 ± 6.3; P = .1) and tissue blood flow (501.7 ± 39.3 vs 494.7 ± 44.4 AU; P = .4) compared with baseline. The expression of endothelin-1 (3.2 ± 0.4 vs 1.8 ± 0.3 RQ; P = .3) and endothelin subtype A (0.7 ± 0.2 vs 0.9 ± 0.2 RQ; P = .5) was not different from the sham group.

CONCLUSIONS

Cardiopulmonary bypass leads to microvascular impairment of jejunal microcirculation, which is associated with the upregulation of endothelin-1 and endothelin subtype A. The administration of vasopressin minimizes these cardiopulmonary bypass-associated alterations.

Post cardiac surgery vasoplegia is associated with high preoperative copeptin plasma concentration

Introduction

Post cardiac surgery vasodilatation (PCSV) is possibly related to a vasopressin deficiency that could relate to chronic stimulation of adeno-hypophysis. To assess vasopressin system activation, a perioperative course of copeptin and vasopressin plasma concentrations were studied in consecutive patients operated on for cardiac surgery.

Methods

Sixty-four consecutive patients scheduled for elective cardiac surgery with cardiopulmonary bypass were studied. Hemodynamic, laboratory and clinical data were recorded before and during cardiopulmonary bypass, and at the eighth postoperative hour (H8). At the same time, blood was withdrawn to determine plasma concentrations of arginine vasopressin (AVP, radioimmunoassay) and copeptin (immunoluminometric assay). PCSV was defined as mean arterial blood pressure < 60 mmHg with cardiac index ≥ 2.2 l/min/m², and was treated with norepinephrine to restore mean blood pressure > 60 mmHg. Patients with PCSV were compared with the other patients (controls). Student's t test, Fisher's exact test, or nonparametric tests (Mann-Whitney, Wilcoxon) were used when appropriate. Correlation between AVP and copeptin was evaluated and receiver-operator characteristic analysis assessed the utility of preoperative copeptin to distinguish between controls and PCSV patients.

Results

Patients who experienced PCSV had significantly higher copeptin plasma concentration before cardiopulmonary bypass (P < 0.001) but lower AVP concentrations at H8 (P < 0.01) than controls. PCSV patients had preoperative hyponatremia and decreased left ventricle ejection fraction, and experienced more complex surgery (redo). The area under the receiver-operator characteristic curve of preoperative copeptin concentration was 0.86 ± 0.04 (95% confidence interval = 0.78 to 0.94; P < 0.001). The best predictive value for preoperative copeptin plasma concentration was 9.43 pmol/l with a sensitivity of 90% and a specificity of 77%.

Conclusions

High preoperative copeptin plasma concentration is predictive of PSCV and suggests an activation of the AVP system before surgery that may facilitate depletion of endogenous AVP stores and a relative AVP deficit after surgery.

Heart failure treatment in the intensive care unit in children

Although pediatric heart failure is generally a chronic, progressive disorder, recovery of ventricular function may occur with some forms of cardiomyopathy. Guidelines for the management of chronic heart failure in adults and children have recently been published by the International Society for Heart and Lung Transplantation the American College of Cardiology, and the American Heart Association. The primary aim of heart failure therapy is to reduce symptoms, preserve long-term ventricular performance, and prolong survival primarily through antagonism of the neurohormonal compensatory mechanisms. Because some medications may be detrimental during an acute decompensation, physicians who manage these patients as inpatients must be knowledgeable about the medications and therapeutic goals of chronic heart failure treatment. Understanding the mechanisms of chronic heart failure may foster improved understanding of the treatment of decompensated heart failure.

Pharmacotherapy for Mechanical Circulatory Support: A Comprehensive Review

Objective

To provide a comprehensive review of the pharmacotherapy associated with the provision of mechanical circulatory support (MCS) to patients with end-stage heart failure and guidance regarding the selection, assessment, and optimization of drug therapy for this population.

Data Sources:

The MEDLINE/PubMed, EMBASE, and Cochrane databases were searched from 1960 to July 2010 for articles published in English using the search terms mechanical circulatory support, ventricular assist system, ventricular assist device, left ventricular assist device, right ventricular assist device, biventricular assist device, total artificial heart, pulsatile, positive displacement, axial, centrifugal, hemostasis, bleeding, hemodynamic, blood pressure, thrombosis, antithrombotic therapy, anticoagulant, antiplatelet, right ventricular failure, ventricular arrhythmia, anemia, arteriovenous malformation, stroke, infection, and clinical pharmacist.

Study Selection And Data Extraction:

All relevant original studies, metaanalyses, systematic reviews, guidelines, and reviews were assessed for inclusion. References from pertinent articles were examined for content not found during the initial search.

Data Synthesis:

MCS has advanced significantly since the first left ventricular assist device was implanted in 1966. Further advancements in MCS technology that occurred in the tatter decade are changing the overall management of end-stage heart failure care and cardiac transplantation. These pumps allow for improved bridge-to-transplant rates, enhanced survival, and quality of life. Pharmacotherapy associated with MCS devices may optimize the performance of the pumps and improve patient outcomes, as well as minimize morbidity related to their adverse effects. This review highlights the knowledge needed to provide appropriate clinical pharmacy services for patients supported by MCS devices.

Conclusions:

The HeartMate II clinical investigators called for the involvement of pharmacists in MCS patient assessment and optimization. Pharmacotherapeutic management of patients supported with MCS devices requires individualized care, with pharmacists as part of the team, based on the characteristics of each pump and recipient.

The cellular mechanisms underlying the inhibitory effects of isoflurane and sevoflurane on arginine vasopressin-induced vasoconstriction

PURPOSE

Arginine vasopressin (AVP) is a potent vasoconstrictor that is sometimes used for the treatment of refractory vasodilatory shock. AVP constricts vascular smooth muscle by increasing both intracellular calcium concentration ([Ca(2+)](i)) and myofilament Ca(2+) sensitivity. However, the modulation of AVP-mediated vasoconstriction by volatile anesthetics remains to be determined. This study investigates the effects of isoflurane and sevoflurane on AVP-induced vasoconstriction and elucidates the underlying mechanisms, with an emphasis on the Ca(2+)-mediated pathways and Ca(2+) sensitization pathways of rat aortic smooth muscle.

METHODS

The effects of isoflurane and sevoflurane on AVP-induced vasoconstriction and on the AVP-induced increase in [Ca(2+)](i) and Rho activity in rat aorta were investigated by isometric force recording, by measuring [Ca(2+)](i) using fluorescence dye, and by Western blotting techniques.

RESULTS

Arginine vasopressin (10⁻⁷M) elicited a transient contractile response that was inhibited by isoflurane and sevoflurane in a concentration-dependent manner. AVP (10⁻⁷ M) induced a transient increase in intracellular Ca(2+) concentration ([Ca(2+)](i)). Isoflurane and sevoflurane also inhibited an AVP-induced increase in [Ca(2+)](i) in a concentration-dependent manner. AVP (10⁻⁷ M) increased the Rho activity that was attenuated by 2 minimum alveolar concentration of sevoflurane (P < 0.01), but not by an equipotent concentration of isoflurane.

CONCLUSION

Arginine vasopressin-induced vasoconstriction is mediated by an increase in [Ca(2+)](i) and by the activation of the Rho-Rho kinase pathway in rat aortic smooth muscle. Although both isoflurane and sevoflurane, at clinically relevant concentrations, attenuate AVP-induced contraction, the cellular mechanisms of their inhibitory effects appear to differ.

Perioperative infusion of low- dose of vasopressin for prevention and management of vasodilatory vasoplegic syndrome in patients undergoing coronary artery bypass grafting-A double-blind randomized study

Preoperative medication by inhibitors of angiotensin-converting enzyme (ACE) in coronary artery patients predisposes to vasoplegic shock early after coronary artery bypass grafting. Although in the majority of the cases this shock is mild, in some of them it appears as a situation, "intractable" to high-catecholamine dose medication. In this study we examined the possible role of prophylactic infusion of low-dose vasopressin, during and for the four hours post-bypass after cardiopulmonary bypass, in an effort to prevent this syndrome. In addition, we studied the influence of infused vasopressin on the hemodynamics of the patients, as well as on the postoperative urine-output and blood-loss. In our study 50 patients undergoing coronary artery bypass grafting were included in a blind-randomized basis. Two main criteria were used for the eligibility of patients for coronary artery bypass grafting: ejection fraction between 30-40%, and patients receiving ACE inhibitors, at least for four weeks preoperatively. The patients were randomly divided in two groups, the group A who were infused with 0.03 IU/min vasopressin and the group B who were infused with normal saline intraoperativelly and for the 4 postoperative hours. Measurements of mean artery pressure (MAP), central venous pressure (CVP), systemic vascular resistance (SVR), ejection fracture (EF), heart rate (HR), mean pulmonary artery pressure (MPAP), cardiac index (CI) and pulmonary vascular resistance (PVR) were performed before, during, and after the operation. The requirements of catecholamine support, the urine-output, the blood-loss, and the requirements in blood, plasma and platelets for the first 24 hours were included in the data collected. The incidence of vasodilatory shock was significantly lower (8% vs 20%) in group A and B respectively (p = 0,042). Generally, the mortality was 12%, exclusively deriving from group B. Postoperatively, significant higher values of MAP, CVP, SVR and EF were recorded in the patients of group A, compared to those of group B. In group A norepinephrine was necessary in fewer patients (p = 0.002) and with a lower mean dose (p = 0.0001), additive infusion of epinephrine was needed in fewer patients (p = 0.001), while both were infused for a significant shorter infusion-period (p = 0.0001). Vasopressin administration (for group A) was associated with a higher 24 hour diuresis) (0.0001).

In conclusion, low-dose of infused vasopressin during cardiopulmonary bypass and for the next 4 hours is beneficial for its postoperative hemodynamic profile, reduces the doses of requirements of catecholamines and contributes to prevention of the postcardiotomy vasoplegic shock in the patient with low ejection fraction who is receiving ACE preoperatively.

Postoperative Care of the Cardiac Surgical Patient

The subspecialty of interventional cardiology began in 1977. Since then, the discipline of interventional cardiology has matured rapidly, particularly with regards to ischemic heart disease. As a result, more patients are undergoing percutaneous catheter interventional therapy for ischemic heart disease and fewer patients are undergoing surgical myocardial revascularization. Those patients referred for surgical revascularization are generally older and have more complex problems. Furthermore, as the population ages more patients are referred to surgery for valvular heart disease. The result of these changes is a population of surgical patients older and sicker than previously treated.

Pharmacological optimization of tissue perfusion

After fluid resuscitation, vasoactive drug treatment represents the major cornerstone for correcting any major impairment of the circulation. However, debate still rages as to the choice of agent, dose, timing, targets, and monitoring modalities that should optimally be used to benefit the patient yet, at the same time, minimize harm. This review highlights these areas and some new pharmacological agents that broaden our therapeutic options.

Children undergoing heart transplant are at increased risk for postoperative vasodilatory shock

OBJECTIVE

To determine the incidence of vasodilatory shock (VDS) in children after cardiopulmonary bypass (CPB), and to describe this syndrome of post-CPB VDS in children.

DESIGN

Prospective, observational.

SETTING

Pediatric and neonatal intensive care units in a tertiary care, children's hospital.

PATIENTS

Three hundred children undergoing CPB.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Three hundred subjects undergoing CPB were evaluated for clinical evidence of VDS following CPB. The incidence of post-CPB VDS was 3%. Characteristics of children who developed VDS: higher peak lactate (6.2 +/- 2.6 vs. 3.0 +/- 2.1 mmol/L; p = 0.0002), higher peak serum blood urea nitrogen (18.5 +/- 4.6 vs. 15.6 +/- 7.2 mg/dL; p = 0.04), lower urine output (1.7 +/- 0.8 vs. 2.6 +/- 0.2 mL/kg/hr; p = 0.04), and fewer intensive care unit free days (14.9 +/- 9.0 vs. 21.1 +/- 7.2 days; p = 0.01). Univariate predictors for the development of post-CPB VDS included children who had heart transplantation (HT) (relative risk [RR], 9.8; 95% confidence interval [CI], 2.7-35.2) or ventricular assist device (VAD) placed (RR, 17.9; 95% CI, 3.8-84.1), a cardiomyopathy diagnosis (RR, 8.5; 95% CI, 2.3-31), age >12 years (RR, 4.5; 95% CI, 1.2-17.0), CPB time >180 minutes (RR, 7.1; 95% CI, 1.9-26.2), and preoperative ventricular dysfunction (RR, 3.7; 95% CI, 1.0-13.4). By stratified analysis, the only independent predictor for the development of VDS was undergoing HT/VAD.

CONCLUSIONS

Post-CPB VDS is uncommon in children. However, children who undergo HT or VAD placement are at high risk for developing post-CPB VDS. Recognition that the overall incidence of post-CPB is low-except in the HT/VAD population-may help guide therapy in the pediatric post-CPB patient.

Arginine vasopressin in the treatment of vasodilatory septic shock

Vasodilatory septic shock is characterized by profound vasodilation of the peripheral circulation, relative refractoriness to catecholamines and a relative deficiency of the posterior pituitary hormone, vasopressin. Arginine vasopressin is effective in restoring vascular tone in vasodilatory septic shock and may be associated with decreased mortality in less severe septic shock as well as improved mortality and decreased renal failure in septic shock patients at risk for renal failure.

The vasopressin and copeptin response in patients with vasodilatory shock after cardiac surgery: a prospective, controlled study

OBJECTIVE

To evaluate arginine vasopressin (AVP) and copeptin plasma concentrations in patients with vasodilatory shock after cardiac surgery.

DESIGN

Prospective, controlled, clinical study.

SETTING

Surgical intensive care unit and cardiac surgery ward in a tertiary university teaching hospital.

PATIENTS AND PARTICIPANTS

Thirty-three critically ill patients with vasodilatory shock after cardiac surgery and ten control patients undergoing uncomplicated aorto-coronary bypass surgery.

MEASUREMENTS AND RESULTS

Hemodynamic, laboratory and clinical data were recorded daily in all patients during the first 7 days after cardiac surgery. At the same time, points blood was withdrawn to determine plasma concentrations of AVP (radioimmunoassay) and copeptin (immunoluminometric assy). Standard tests, a mixed effects model and regression analyses were used for statistical analysis. The course of AVP was significantly different between groups (P < 0.001). While AVP concentrations were lower in the study group on the first postoperative day, they were higher than that in the control group from postoperative day 3 on. There was no difference in the postoperative AVP response between study patients with or without chronic angiotensin-converting enzyme inhibitor therapy. Except during continuous veno-venous hemofiltration, AVP and copeptin correlated significantly with each other (P < 0.001; r = 0.749).

CONCLUSIONS

The AVP response to cardiac surgery is significantly different between patients with vasodilatory shock and patients undergoing uncomplicated aorto-coronary bypass surgery. Although no causative relationship between AVP concentrations and cardiovascular instability can be drawn from these results, our data support the hypothesis that inadequately low AVP plasma levels contribute to the failure to restore vascular tone in vasodilatory shock after cardiac surgery.

Arginine vasopressin to manage hypoxemic infants after stage I palliation of single ventricle lesions

OBJECTIVE

Management of patients with single ventricle physiology following stage I palliation procedures is often challenging, with optimization of the ratio of pulmonary-to-systemic blood flow as an important goal. Persistent hypoxemia may be a manifestation of elevated pulmonary vascular resistance and therefore decreased blood flow to the lungs. In such situations, the use of arginine vasopressin to increase systemic vascular resistance may be an effective strategy to improve pulmonary blood flow and maintain adequate pulmonary-to-systemic blood flow ratio. We describe three infants in whom persistent hypoxemia improved after institution of arginine vasopressin.

DESIGN

Retrospective chart review.

SETTING

Twenty-four bed medical-surgical pediatric intensive care unit at a large tertiary care academic hospital.

PATIENTS

Three neonates with single ventricle physiology who received arginine vasopressin in the setting of hypoxemia following stage I palliation.

RESULTS

Arginine vasopressin was initiated in all three patients for hypoxemia with a goal to increase systemic vascular resistance and generate a higher driving pressure for pulmonary blood flow. Twelve hours after arginine vasopressin initiation, systemic arterial saturation as determined by pulse oximetry and blood pressure increased, whereas heart rate, inotrope score, and Fio2 decreased in all three patients. Urine output was maintained and arterial lactate decreased during this time. Pulmonary-to-systemic flow ratio increased in one patient in whom it could be determined.

CONCLUSION

In patients with single ventricle physiology and persistent hypoxemia following stage I palliation, administration of arginine vasopressin could improve oxygenation possibly by increasing systemic vascular resistance and therefore the pulmonary blood flow.

Vasopressin, when added to norepinephrine, was not associated with increased predicted mortality after cardiac surgery

BACKGROUND AND AIMS

Arginin vasopressin (AVP) is a potent vasoconstrictor which has been used in vasodilatory shock when therapy with catecholamines and fluids has failed. In this study we evaluated the association of AVP with organ failure and mortality in cardiac surgical patients suffering from vasodilatory shock refractory to norepinephrine (NE) treatment.

MATERIAL AND METHODS

Cardiac surgical patients who received AVP in addition to NE (N=33, AVP-group) and 33 control patients (NE group) who were treated with an equal dose of NE compared with AVP patients when AVP infusion started. Data on preoperative risk factors according to EuroSCORE and predicted mortality calculated by logistic EuroSCORE were collected preoperatively. Data on hemodynamics, organ dysfunctions, length of intensive care unit stay and mortality were collected.

RESULTS

EuroSCORE did not differ between the groups, AVP:10.4 +/- 3.9 vs. NE 8.9 +/- 4.0. Observed 30 day mortality was lower than predicted in both groups, AVP: 7 (21.7%) vs. predicted mortality 25.9% and NE: 2 (6.1%) vs. 16.0%, respectively. There were more renal complications (36.4% vs. 9.1%, p = 0.008) and infections (30.3% vs. 3.0%, p = 0.003) in patients receiving AVP. Cardiovascular complications did not differ between the groups.

CONCLUSIONS

In this prospectively observed cohort of cardiac surgical patients, AVP did not increase mortality predicted by Euroscore. Anyhow renal and infection complications were common.

Vasopressin versus norepinephrine infusion in patients with septic shock

BACKGROUND

Vasopressin is commonly used as an adjunct to catecholamines to support blood pressure in refractory septic shock, but its effect on mortality is unknown. We hypothesized that low-dose vasopressin as compared with norepinephrine would decrease mortality among patients with septic shock who were being treated with conventional (catecholamine) vasopressors.

METHODS

In this multicenter, randomized, double-blind trial, we assigned patients who had septic shock and were receiving a minimum of 5 microg of norepinephrine per minute to receive either low-dose vasopressin (0.01 to 0.03 U per minute) or norepinephrine (5 to 15 microg per minute) in addition to open-label vasopressors. All vasopressor infusions were titrated and tapered according to protocols to maintain a target blood pressure. The primary end point was the mortality rate 28 days after the start of infusions.

RESULTS

A total of 778 patients underwent randomization, were infused with the study drug (396 patients received vasopressin, and 382 norepinephrine), and were included in the analysis. There was no significant difference between the vasopressin and norepinephrine groups in the 28-day mortality rate (35.4% and 39.3%, respectively; P=0.26) or in 90-day mortality (43.9% and 49.6%, respectively; P=0.11). There were no significant differences in the overall rates of serious adverse events (10.3% and 10.5%, respectively; P=1.00). In the prospectively defined stratum of less severe septic shock, the mortality rate was lower in the vasopressin group than in the norepinephrine group at 28 days (26.5% vs. 35.7%, P=0.05); in the stratum of more severe septic shock, there was no significant difference in 28-day mortality (44.0% and 42.5%, respectively; P=0.76). A test for heterogeneity between these two study strata was not significant (P=0.10).

CONCLUSIONS

Low-dose vasopressin did not reduce mortality rates as compared with norepinephrine among patients with septic shock who were treated with catecholamine vasopressors. (Current Controlled Trials number, ISRCTN94845869 [controlled-trials.com].).