STUDIES IN CLINICAL SHOCK AND HYPOTENSION. II. HEMODYNAMIC EFFECTS OF NOREPINEPHRINE AND ANGIOTENSIN

Review of Postoperative Care for Heart Transplant Recipients

The early postoperative management strategies after heart transplantation include optimizing the function of the denervated heart, correcting the causes of hemodynamic instability, and initiating and maintaining immunosuppressive therapy, allograft rejection surveillance, and prophylaxis against infections caused by immunosuppression. The course of postoperative support is influenced by the quality of allograft myocardial protection prior to implantation and reperfusion, donor-recipient heart size matching, surgical technique of orthotopic heart transplantation, and patient factors (eg, preoperative condition, immunologic compatibility, postoperative vasomotor tone, severity and reversibility of pulmonary vascular hypertension, pulmonary function, mediastinal blood loss, and end-organ perfusion). This review provides an overview of the early postoperative care of recipients and includes a brief description of the surgical techniques for orthotopic heart transplantation.

The pharmacotherapeutic options in patients with catecholamine-resistant vasodilatory shock

INTRODUCTION

Septic and vasoplegic shock are common types of vasodilatory shock (VS) with high mortality. After fluid resuscitation and the use of catecholamine-mediated vasopressors (CMV), vasopressin, angiotensin II, methylene blue (MB) and hydroxocobalamin can be added to maintain blood pressure.

AREAS COVERED

VS treatment utilizes a phased approach with secondary vasopressors added to vasopressor agents to maintain an acceptable mean arterial pressure (MAP). This review covers additional vasopressors and adjunctive therapies used when fluid and catecholamine-mediated vasopressors fail to maintain target MAP.

EXPERT OPINION

Evidence supporting additional vasopressor agents in catecholamine resistant VS is limited to case reports, series, and a few randomized control trials (RCTs) to guide recommendations. Vasopressin is the most common agent added next when MAPs are not adequately supported with CMV. VS patients failing fluids and vasopressors with cardiomyopathy may have cardiotonic agents such as dobutamine or milrinone added before or after vasopressin. Angiotensin II, another class of vasopressor is used in VS to maintain adequate MAP. MB and/or hydoxocobalamin, vitamin C, thiamine and corticosteroids are adjunctive therapies used in refractory VS. More RCTs are needed to confirm the utility of these drugs, at what doses, which combinations and in what order they should be given.

Renin-Angiotensin-Aldosterone System and Immunomodulation: A State-of-the-Art Review

The renin–angiotensin system (RAS) has long been described in the field of cardiovascular physiology as the main player in blood pressure homeostasis. However, other effects have since been described, and include proliferation, fibrosis, and inflammation. To illustrate the immunomodulatory properties of the RAS, we chose three distinct fields in which RAS may play a critical role and be the subject of specific treatments. In oncology, RAS hyperactivation has been associated with tumor migration, survival, cell proliferation, and angiogenesis; preliminary data showed promise of the benefit of RAS blockers in patients treated for certain types of cancer. In intensive care medicine, vasoplegic shock has been associated with severe macro- and microcirculatory imbalance. A relative insufficiency in angiotensin II (AngII) was associated to lethal outcomes and synthetic AngII has been suggested as a specific treatment in these cases. Finally, in solid organ transplantation, both AngI and AngII have been associated with increased rejection events, with a regional specificity in the RAS activity. These elements emphasize the complexity of the direct and indirect interactions of RAS with immunomodulatory pathways and warrant further research in the field.

Roles of angiotensin II as vasopressor in vasodilatory shock

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

Role of angiotensin II in treatment of refractory distributive shock

OBJECTIVE

Clinical data and gaps in knowledge regarding angiotensin II (AT2), which was approved by the Food and Drug Administration in December 2017 via priority review for treatment of septic and other vasodilatory shock, is discussed.

SUMMARY

AT2 is an endogenous peptide that raises blood pressure via vasoconstriction and increased aldosterone release. It was previously available but withdrawn from the US market; previous low-quality research describes increases in mean arterial pressure (MAP). The recent approval of AT2 was based on data from a Phase III randomized trial comparing i.v. AT2 (n = 163) with placebo use (n = 158) in patients with vasodilatory shock receiving high doses of other vasopressors. AT2 significantly increased achievement of the primary endpoint, MAP response at 3 hours after the start of infusion, relative to placebo use (69.9% [n = 114] versus 23.4% [n = 37], p < 0.0001). Serious adverse events occurred in 60.7% (n = 99) and 67.1% (n = 106) of patients treated with AT2 and placebo recipients, respectively, including venous and arterial thromboembolic events (12.9% [n = 21] and 5.1% [n = 8], respectively). No significant effects of AT2 on 7- or 28-day mortality were seen among all patients in the ATHOS-3 trial. However, post hoc analyses suggested that AT2 may reduce mortality in patients with low baseline AT2 levels, exaggerated response to AT2, and acute kidney injury receiving concomitant renal replacement therapy. Overall, due to shortcomings of the ATHOS-3 trial data and the absence of confirmatory studies, the optimal place in therapy of AT2 for vasodilatory shock cannot be determined with confidence.

CONCLUSION

Intravenous AT2 represents a novel treatment strategy for refractory septic or other vasodilatory shock, although findings of safety and efficacy have not been replicated and the drug's optimal place in therapy is uncertain.

Angiotensin II (Giapreza): A Distinct Mechanism for the Treatment of Vasodilatory Shock

Septic shock, a form of vasodilatory shock associated with high morbidity and mortality, requires early and effective therapy to improve patient outcomes. Current management of septic shock includes the use of intravenous fluids, catecholamines, and vasopressin for hemodynamic support to ensure adequate perfusion. Despite these interventions, hospital mortality rates are still greater than 40%. Practitioners are continuously faced with cases of refractory shock that are associated with poor clinical outcomes. In December of 2017, the Food and Drug Administration approved the first synthetic human angiotensin II, a potent vasoconstrictor, to increase blood pressure in adults with septic or other distributive shock. This approval was based (ATHOS) on the results from the Angiotensin II for the Treatment of High Output Shock study. In this randomized, double-blind, placebo-controlled trial, patients in the angiotensin II group achieved higher rates of target mean arterial pressure and had lower catecholamine requirements in the first 3 hours of therapy compared with patients in the placebo group. There was no significant difference in the 28-day mortality. Safety issues including the risk of thromboembolic events, infection, and delirium have made clinicians cautious in adopting angiotensin II into practice. Ongoing studies are needed to more clearly define the role of this agent and its utility in the management of shock.

Vasodilatory shock in the ICU and the role of angiotensin II

PURPOSE OF REVIEW

There are limited vasoactive options to utilize for patients presenting with vasodilatory shock. This review discusses vasoactive agents in vasodilatory, specifically, septic shock and focuses on angiotensin II as a novel, noncatecholamine agent and describes its efficacy, safety, and role in the armamentarium of vasoactive agents utilized in this patient population.

RECENT FINDINGS

The Angiotensin II for the Treatment of High-Output Shock 3 study evaluated angiotensin II use in patients with high-output, vasodilatory shock and demonstrated reduced background catecholamine doses and improved ability to achieve blood pressure goals associated with the use of angiotensin II. A subsequent analysis showed that patients with a higher severity of illness and relative deficiency of intrinsic angiotensin II and who received angiotensin II had improved mortality rates. In addition, a systematic review showed infrequent adverse reactions with angiotensin II demonstrating its safety for use in patients with vasodilatory shock.

SUMMARY

With the approval and release of angiotensin II, a new vasoactive agent is now available to utilize in these patients. Overall, the treatment for vasodilatory shock should not be a one-size fits all approach and should be individualized to each patient. A multimodal approach, integrating angiotensin II as a noncatecholamine option should be considered for patients presenting with this disease state.

Angiotensin II in Vasodilatory Shock

The Angiotensin II for the Treatment of Vasodilatory Shock (ATHOS-3) trial demonstrated the vasopressor effects and catecholamine-sparing properties of angiotensin II. As a result, the Food and Drug Administration has approved angiotensin II for the treatment of vasodilatory shock. This review details the goals of treatment of vasodilatory shock in addition to the history, current use, and recent research regarding the use of angiotensin II. An illustrative case of the use of angiotensin II is also incorporated for understanding the clinical utility of the drug.

Novel Vasopressors in the Treatment of Vasodilatory Shock: A Systematic Review of Angiotensin II, Selepressin, and Terlipressin

Study Objective:

Vasodilatory shock is the most common type of shock. Catecholamine vasopressors are the cornerstone of hemodynamic therapy but carry risks. Angiotensin II (AT2) was recently approved, and other novel agents (selepressin and terlipressin) are under investigation and used outside the United States (terlipressin). We performed a systematic review to summarize the efficacy and safety of these novel vasopressors and to offer guidance on their appropriate use.

Design:

Systematic review of controlled trials.

Methods:

Numerous databases were searched using terms related to angiotensin II, selepressin, terlipressin, vasopressor, and shock. Twenty-one citations, including 16 prospective comparative trials and 5 post hoc analyses reporting effects of AT2, selepressin, and terlipressin, were reviewed for data on outcomes related to hemodynamic measures, mortality, severity and duration of illness, concomitant vasopressor utilization, and adverse effects. Findings from eligible literature are described qualitatively using Cochrane methods.

Results:

Fourteen controlled trials were assessed after exclusion of 2 dated trials of a distinct AT2 formulation. Trials are limited for AT2 (n = 2) and selepressin (n = 1), while terlipressin was investigated in 11 small trials. Overall, the trials have an unclear risk of bias. Most report mean arterial pressure (MAP) as primary end point, and all indicate novel vasopressors increase MAP compared to placebo and to a similar degree as with catecholamine vasopressors. Mortality findings are preliminary, as they have been limited to specific subgroups in trials of terlipressin and post hoc analyses of one trial of AT2. Trials reported safety concerns for each agent including thromboembolism with AT2 and ischemia with terlipressin/selepressin.

Conclusion:

In this systematic review, controlled trials of novel vasopressors in treatment of vasodilatory shock were limited and of low quality. Angiotensin II, selepressin, and terlipressin appear to significantly increase MAP, but further study is required, particularly for selepressin, to determine their safety, efficacy, and role in treatment of vasodilatory shock.

Angiotensin II: a new therapeutic option for vasodilatory shock

Angiotensin II (Ang II), part of the renin-angiotensin-aldosterone system (RAS), is a potent vasoconstrictor and has been recently approved for use by the US Food and Drug Administration in high-output shock. Though not a new drug, the recently published Angiotensin II for the Treatment of High Output Shock (ATHOS-3) trial, as well as a number of retrospective analyses have sparked renewed interest in the use of Ang II, which may have a role in treating refractory shock. We describe refractory shock, the unique mechanism of action of Ang II, RAS dysregulation in shock, and the evidence supporting the use of Ang II to restore blood pressure. Evidence suggests that Ang II may preferentially be of benefit in acute kidney injury and acute respiratory distress syndrome, where the RAS is known to be disrupted. Additionally, there may be a role for Ang II in cardiogenic shock, angiotensin converting enzyme inhibitor overdose, cardiac arrest, liver failure, and in settings of extracorporeal circulation.

A Blast From the Past: Revival of Angiotensin II for Vasodilatory Shock

OBJECTIVE

To review and summarize data on angiotensin II (AT-II), approved by the Food and Drug Administration (FDA) in December 2017 to increase blood pressure in adults with septic or other distributive shock.

DATA SOURCES

A PubMed/MEDLINE search was conducted using the following terms: (angiotensin ii OR angiotensin 2) AND (shock) from 1966 to February 2018.

STUDY SELECTION AND DATA EXTRACTION

A total of 691 citations were reviewed with only relevant clinical data extracted.

DATA SYNTHESIS

AT-II is a peptide hormone with a multitude of physiological effects-namely, vasoconstriction of venous and arterial smooth muscle. The priority approval granted by the FDA was secondary to a phase 3 study of patients receiving at least 0.2 µg/kg/min of norepinephrine or equivalent for vasodilatory shock. Compared with placebo, AT-II had a significantly higher rate of response, defined as a mean arterial pressure of 75 mm Hg or an increase of 10 mm Hg. No significant difference was found in death by day 28.

CONCLUSIONS

AT-II is a newly available vasoactive agent with a novel mechanism for the treatment of distributive shock. Further research is needed to define its exact role in therapy of shock states, identify patients most likely to benefit, and further study its safety profile in critical illness.

Angiotensin in Critical Care

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2018. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2018 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901 .

The effect of angiotensin II on blood pressure in patients with circulatory shock: a structured review of the literature

BACKGROUND

Circulatory shock is a common syndrome with a high mortality and limited therapeutic options. Despite its discovery and use in clinical and experimental settings more than a half-century ago, angiotensin II (Ang II) has only been recently evaluated as a vasopressor in distributive shock. We examined existing literature for associations between Ang II and the resolution of circulatory shock.

METHODS

We searched PubMed, MEDLINE, Ovid, and Embase to identify all English literature accounts of intravenous Ang II in humans for the treatment of shock (systolic blood pressure [SBP] ≤ 90 mmHg or a mean arterial pressure [MAP] ≤ 65 mmHg), and hand-searched the references of extracted papers for further studies meeting inclusion criteria. Of 3743 articles identified, 24 studies including 353 patients met inclusion criteria. Complete data existed for 276 patients. Extracted data included study type, publication year, demographics, type of shock, dosing of Ang II or other vasoactive medications, and changes in BP, lactate, and urine output. BP effects were grouped according to type of shock, with additional analyses completed for patients with absent blood pressure. Shock was distributive (n = 225), cardiogenic (n = 38), or from other causes (n = 90). Blood pressure as absent in 18 patients.

RESULTS

For the 276 patients with complete data, MAP rose by 23.4% from 63.3 mmHg to 78.1 mmHg in response to Ang II (dose range: 15 ng/kg/min to 60 mcg/min). SBP rose by 125.2% from 56.9 mmHg to 128.2 mmHg (dose range: 0.2 mcg/min to a 1500 mcg bolus). A total of 271 patients with complete data were determined to exhibit a BP effect which was directly associated with Ang II. Subgroups (patients with cardiogenic, septic, and other types of shock) exhibited similar increases in BP. In patients with absent BP, deemed to be cardiac arrest, return of spontaneous circulation (ROSC) was achieved, and BP increased by an average of 107.3 mmHg in 11 of 18 patients. The remaining seven patients with cardiac arrest did not respond.

CONCLUSIONS

Intravenous Ang II is associated with increased BP in patients with cardiogenic, distributive, and unclassified shock. A role may exist for Ang II in restoring circulation in cardiac arrest.

Clinical Experience With IV Angiotensin II Administration: A Systematic Review of Safety

OBJECTIVE

Angiotensin II is an endogenous hormone with vasopressor and endocrine activities. This is a systematic review of the safety of IV angiotensin II.

DATA SOURCES

PubMed, Medline, Scopus, and Cochrane.

STUDY SELECTION

Studies in which human subjects received IV angiotensin II were selected whether or not safety was discussed.

DATA EXTRACTION

In total, 18,468 studies were screened by two reviewers and one arbiter. One thousand one hundred twenty-four studies, in which 31,281 participants received angiotensin II (0.5-3,780 ng/kg/min), were selected. Data recorded included number of subjects, comorbidities, angiotensin II dose and duration, pressor effects, other physiologic and side effects, and adverse events.

DATA SYNTHESIS

The most common nonpressor effects included changes in plasma aldosterone, renal function, cardiac variables, and electrolytes. Adverse events were infrequent and included headache, chest pressure, and orthostatic symptoms. The most serious side effects were exacerbation of left ventricular failure in patients with congestive heart failure and bronchoconstriction. One patient with congestive heart failure died from refractory left ventricular failure. Refractory hypotensive shock was fatal in 55 of 115 patients treated with angiotensin II in case studies, cohort studies, and one placebo-controlled study. One healthy subject died after a pressor dose of angiotensin II was infused continuously for 6 days. No other serious adverse events attributable to angiotensin II were reported. Heterogeneity in study design prevented meta-analysis.

CONCLUSION

Adverse events associated with angiotensin II were infrequent; however, exacerbation of asthma and congestive heart failure and one fatal cerebral hemorrhage were reported. This systematic review supports the notion that angiotensin II has an acceptable safety profile for use in humans.

The Physiology of Early Goal-Directed Therapy for Sepsis

In 2001, Rivers and colleagues published a randomized controlled trial of early goal-directed therapy (EGDT) for the treatment of sepsis. More than a decade later, it remains a landmark achievement. The study proved the benefits of early aggressive treatment of sepsis. However, many questions remain about specific aspects of the complex EGDT algorithm. Recently, 3 large trials attempted to replicate these results. None of the studies demonstrated a benefit of an EGDT protocol for sepsis. This review explores the physiologic basis of goal-directed therapy, including the hemodynamic targets and the therapeutic interventions. An understanding of the physiologic basis of EGDT helps reconcile the results of the clinical trials.

Vasopressor and Inotropic Management Of Patients With Septic Shock

Numerous studies have evaluated the role of vasopressors and inotropes in the management of septic shock. This review assesses available evidence for the use of specific vasopressors in the management of septic shock. Use of adjunctive vasopressor therapy is also evaluated, examining the potential value of individual agents. Lastly, inotropic agents are evaluated for use in patients with myocardial dysfunction.

Studies in clinical shock and hypotension: VI. Relationship between left and right ventricular function

Left ventricular end diastolic (LVEDP) and mean right atrial (RAP) pressures were recorded simultaneously in 30 patients with shock (14 acute myocardial infarction, 10 acute pulmonary embolism or severe bronchopulmonary disease, and 6 sepsis). Myocardial infarction was characterized by a predominant increase in LVEDP, pulmonary disease by a predominant increase in RAP, and sepsis by a normal relationship between LVEDP and RAP. In all three groups a significant positive correlation was noted between RAP and LVEDP, with the regression line in cor pulmonale deviated significantly toward the RAP axis and the regression line in myocardial infarction exhibiting a zero RAP intercept at an elevated LVEDP.Low cardiac outputs with elevated LVEDP in myocardial infarction indicated severe left ventricular failure. Low outputs with elevated RAP in cor pulmonale were consistent with right ventricular overload. Although cardiac outputs often were normal in sepsis, low outputs with elevated cardiac filling pressures in some patients were consistent with a hemodynamic or humoral-induced generalized depression of cardiac performance.Vasoconstrictor and inotropic drugs often produced a functional disparity between the two ventricles, with the gradient between LVEDP and RAP increasing, apparently because of an increase in left ventricular work or an inadequacy of left ventricular oxygen delivery. Acute plasma volume expansion with dextran in patients with pulmonary vascular disease resulted in a somewhat more rapid rise in RAP than in LVEDP. In septic and myocardial infarction shock, however, LVEDP and RAP usually rose proportionally, with the absolute rise of LVEDP surpassing that of RAP. Although the absolute level of the central venous pressure thus may not be a reliable indicator of left ventricular function in shock, changes in venous pressure during acute plasma volume expansion should serve as a fairly safe guide to changes in LVEDP.

Effect of norepinephrine on the outcome of septic shock

OBJECTIVE

Despite increasingly sophisticated critical care, the mortality of septic shock remains elevated. Accordingly, care remains supportive. Volume resuscitation combined with vasopressor support remains the standard of care as adjuvant therapy, and many consider dopamine to be the pressor of choice. Because of fear of excessive vasoconstriction, norepinephrine is considered to be deleterious. The present study was designed to identify factors associated with outcome in a cohort of septic shock patients. Special attention was paid to hemodynamic management and to the choice of vasopressor used, to determine whether the use of norepinephrine was associated with increased mortality.

DESIGN

Prospective, observational, cohort study.

SETTING

Intensive care unit of a university hospital.

PATIENTS

Ninety-seven adult patients with septic shock.

MEASUREMENTS AND MAIN RESULTS

Data from these patients were examined to select variables independently and significantly associated with outcome during the hospital stay. Nineteen clinical, biological, and hemodynamic variables were collected at study entry or during the first 48-72 hrs and analyzed for each patient. A stepwise logistic regression analysis and a model building strategy were used to identify variables independently and significantly associated with outcome. The overall hospital mortality was 73% (71 patients). Five variables were significantly associated with outcome. One factor was strongly associated with a favorable outcome: the use of norepinephrine as part of the hemodynamic support of the patients. The 57 patients who were treated with norepinephrine had significantly lower hospital mortality (62% vs. 82%, p < .001; relative risk = 0.68; 95% confidence interval = 0.54-0.87) than the 40 patients treated with vasopressors other than norepinephrine (high-dose dopamine and/or epinephrine). Four variables were associated with a poor outcome and significantly higher hospital mortality: pneumonia as a cause of septic shock (82% vs. 61%, p < .03; relative risk = 1.47; 95% confidence interval = 1.07-1.77), organ system failure index < or = 3 (92% vs. 60%, p < .001; relative risk = 1.47; 95% confidence interval = 1.17-1.82), low urine output at entry to the study (88% vs. 60%, p < .01; relative risk = 1.44; 95% confidence interval = 1.06-1.87), and admission blood lactate concentration > 4 mmol/L (91% vs. 63%, p < .01; relative risk = 1.60; 95% confidence interval = 1.27-1.84).

CONCLUSIONS

Our results indicate that the use of norepinephrine as part of hemodynamic management may influence outcome favorably in septic shock patients. The data contradict the notion that norepinephrine potentiates end-organ hypoperfusion, thereby contributing to increased mortality. However, the present study suffers from some limitation because of its nonrandomized, open-label, observational design. Hence, a randomized clinical trial is needed to clearly establish that norepinephrine improves mortality of patients with septic shock, as compared with high-dose dopamine or epinephrine. Pneumonia as the cause of septic shock, high blood lactate concentration, and low urine output on admission are strong indicators of a poor prognosis. Multiple organ failure is confirmed as a reliable predictor of mortality in septic patients.

Norepinephrine or dopamine for the treatment of hyperdynamic septic shock?

STUDY OBJECTIVE

To compare the ability of dopamine and norepinephrine to reverse hemodynamic and metabolic abnormalities of human hyperdynamic septic shock.

DESIGN

Prospective, double-blind, randomized trial.

SETTING

An ICU in a university hospital.

PATIENTS

Adult patients with hyperdynamic septic shock after fluid resuscitation.

INTERVENTIONS

Patients were assigned to receive either dopamine (2.5 to 25 micrograms/kg/min) or norepinephrine (0.5 to 5.0 micrograms/kg/min). If hemodynamic and metabolic abnormalities were not corrected with the maximum dose of one drug, the other was added.

MEASUREMENTS AND RESULTS

The aim of therapy was to achieve and maintain for at least 6 h all of the following: (1) systemic vascular resistance index > 1,100 dynes.s/cm5.m2 and/or mean systemic blood pressure > or = 80 mm Hg; (2) cardiac index > or = 4.0 L/min/m2; (3) oxygen delivery > 550 ml/min/m2; and (4) oxygen uptake > 150 ml/min/m2. With the use of dopamine 10 to 25 micrograms/kg/min, 5 of 16 patients (31 percent) were successfully treated, as compared with 15 of 16 patients (93 percent) by norepinephrine at a dose of 1.5 +/- 1.2 micrograms/kg/min (p < 0.001). Ten of 11 patients who did not respond to dopamine and remained hypotensive and oliguric were successfully treated with the addition of norepinephrine.

CONCLUSIONS

At the doses tested, norepinephrine was found, in the present study, to be more effective and reliable than dopamine to reverse the abnormalities of hyperdynamic septic shock. In the great majority of the study patients, norepinephrine was able to increase mean perfusing pressure without apparent adverse effect on peripheral blood flow or on renal blood flow (since urine flow was reestablished). At the same time, oxygen uptake was increased.

[Use of norepinephrine in the treatment of septic shock]

The effects of noradrenaline were studied in 16 patients, with either a hyperkinetic septic shock syndrome or a septic shock resistant to dobutamine treatment. The study aimed to restore normal tissue perfusion pressure, assessed by a return to normal of urine output or blood pressure. An optimal left ventricular filling pressure, estimated by the pulmonary capillary wedge pressure, was obtained for each patient using a Swan-Ganz catheter. The administration of 10.6 +/- 0.5 micrograms.kg-1.min-1 dobutamine (starting dose: 6 micrograms.kg-1.min-1) was started when the cardiac index (CI) was less than 3.3 l.min-1.m-2 after vascular filling with plasma expanders. Patients became eligible for noradrenaline treatment when they fulfilled the following conditions: arterial systolic pressure (Pasys) less than or equal to 90 mmHg; systemic vascular resistances less than or equal to 600 dyn.s.cm-5; CI greater than 3.5 l.min-1.m-2; persistent oliguria (less than 30 ml.h-1). This drug was given at a constant rate with a starting dose of 0.5 micrograms.kg-1.min-1, increased every 10 min by 0.3 to 0.6 micrograms.kg-1.min-1 according to the effects on Pasys and hourly urine output. Eight patients received noradrenaline alone; the efficient dose was 0.9 +/- 0.2 micrograms.kg-1.min-1, and it was used for a mean 5.1 +/- 1 days. CI increased in those patients who were given both noradrenaline and dobutamine. Thirteen out of the 16 patients had a dramatic increase in urine output; only three patients remained oliguric. There were no effects on serum creatinine concentration, anion gap, intrapulmonary shunt and oxygen consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Haemodynamic responses to specific renin-angiotensin inhibitors in hypertension and congestive heart failure. A review

The renin-angiotensin system is an important regulator of vascular resistance in many patients with hypertension and congestive heart failure. To quantitatively evaluate this contribution requires correlation of markers of the renin-angiotensin system with haemodynamic parameters, notably blood pressure, cardiac output, and calculated systemic vascular resistance. In addition, to determine ventricular loading properties, assessment of cardiac filling pressures is also required. The availability of specific pharmacological inhibitors of the renin-angiotensin system greatly enhances such correlation, as the haemodynamic consequence of blocking the renin-angiotensin system can then more fully identify its contribution. In the last decade, highly specific pharmacological inhibitors have become available to serve such a purpose. Renin inhibitory peptides, and renin-specific antibodies can block the rate-limiting step of the renin-angiotensin cascade: namely, the cleavage of 4 amino acids from the angiotensinogen substrate by renin. However, this method of blockade is still at the early stages of investigation. More readily available are converting enzyme inhibitors which block the formation of angiotensin II, the potent vasoconstrictor which mediates increased systemic vascular resistance, and angiotensin II analogues which compete with endogenous angiotensin II for vascular and adrenal receptors. Although hypertension and chronic congestive heart failure are clinically distinct entities in many respects, their common bond is the fact that both pathological mechanisms are mediated by an increase of systemic vascular resistance. The implications of blocking the resulting vasoconstriction in both entities are therefore quite similar. This review summarises our present knowledge of the contribution of the renin-angiotensin system to the vasoconstriction of hypertension and congestive heart failure, and also summarises the haemodynamic consequences of such inhibition. The implications of the response to these specific pharmacological probes, as well as their limitations, are discussed. Their importance rests not only in their therapeutic application, but also in their contribution as probes for pathophysiological mechanisms of vasoconstriction in cardiovascular disease.

Estimation of angiotensin II receptor activity in chronic congestive heart failure

The renin-angiotensin system has been shown to participate in the pathophysiology of chronic heart failure in many patients. However, the immediate assessment of this contribution in individual patients may sometimes be difficult. As a pharmacologic estimate of angiotensin II receptor activity, we infused the angiotensin II analogue, saralasin, in 20 patients with severe chronic congestive heart failure (CHF). The infusion resulted in blood pressure responses ranging from an agonist pressor response (increased systemic resistance) in patients with low intrinsic renin-angiotensin system activity, to an antagonist depressor response (decreased systemic resistance) in patients with marked activation of the renin-angiotensin system. The ability of the saralasin response to pharmacologically estimate angiotensin II receptor activity in CHF was further revealed by two physiologic maneuvers that decrease endogenous circulating angiotensin II and angiotensin II receptor occupancy. Both converting enzyme inhibition with captopril and sodium repletion, factors known to decrease endogenous angiotensin II activity, provoked agonist responses to saralasin infusion. Furthermore, saralasin was able to reverse the orthostatic hypotension precipitated by converting enzyme inhibition of angiotensin-dependent vascular tone. In summary, saralasin provided a means to estimate angiotensin receptor activity and may therefore serve as a probe of angiotensin-mediated vasoconstriction in the pathophysiology of chronic CHF.

Arterial oxygenation and pulmonary function with Saralasin in chronic lung disease

During our earlier saralasin infusion study in hypertensive patients, we found a drug-induced rise in arterial oxygen tension (PaO2) associated with unchanged mixed venous PO2 or the PaCO2 and unrelated to cardiopulmonary hemodynamic changes. To test the hypothesis that saralasin improved pulmonary mechanics, blood gases, lung mechanics, lung volumes, diffusing capacity, and distribution of ventilation were analyzed and cardiac output (CO) measured in 12 normotensive men with chronic pulmonary disease before and during a 2 1/2 hour infusion of Saralasin (5 micrograms/kg/min). The PaO2 increased from a mean of 63 +/- 3 (SEM) to 70 +/- 3 mm Hg (p less than 0.001), while the CO decreased from 6.81 +/- 0.52 L/min to 6.18 +/- 0.48 L/min (p less than 0.005). The change in (delta)CO correlated with delta PaO2 (r = -0.67, p less than 0.05). Total systemic vascular resistance rose from 1,201 +/- 134 to 1,353 +/- 147 dynes X sec X cm5 (p less than 0.001). The PaCO2 and other measurements remained unchanged. We conclude that saralasin raised the PaO2 not by changing pulmonary function or mechanics, but by redistributing pulmonary blood flow and improving the ventilation-perfusion relationship.

Acute effects of captopril on cardiopulmonary hemodynamics and renin-angiotensin-aldosterone and bradykinin profile in hypertension

Hemodynamic variables were measured and plasma renin activity (PRA), angiotensin II (AII), aldosterone, and bradykinin assays performed in 21 hypertensive men on regular diet and thiazide diuretics before and 60 to 90 minutes after 25 mg oral captopril. Heart rate, right and left ventricular filling pressures, mean cardiac index (CI), and pulmonary vascular resistance (PVR) remained unchanged. The mean intra-arterial pressure (MAP) fell from 140 +/- 5 to 116 +/- 6 mm Hg (p less than 0.001) correlating with reduction of systemic vascular resistance (SVR) (r = 0.87, p less than 0.001), control PRA (r = 0.59, p less than 0.01), and All levels (r = 0.72, p less than 0.005) but not with control bradykinin or its postcaptopril rise (p less than 0.01). The fall in SVR correlated with reduction in plasma All (r = 0.80, p less than 0.001) and aldosterone concentrations (r = 0.53, p less than 0.05). Of four patients (19%) with precipitous fall in MAP after captopril, three needed volume expansion for circulatory support. We conclude: (1) All reduction by captpril and not bradykinin potentiation explains most of the agent's hemodynamic response in hypertensive circulation, (2) endogenous All may have a supportive role for SVR and possibly for CI but not for PVR, and (3) extra precaution is warranted while captopril is being started in patients taking diuretics.

Pirbuterol: a new oral sympathomimetic amine for the treatment of congestive heart failure

Fourteen patients with refractory congestive heart failure (CHF) were given a single oral dose ranging from 5 to 30 mg of the new sympathomimetic drug pirbuterol. Hemodynamic measurements and plasma pirbuterol levels were obtained at control and then serially for 6 hours following drug administration. The optimal pirbuterol dose range was determined to be 20 to 30 mg. Ten patients received 20 to 30 mg pirbuterol. In this group cardiac index was significantly increased (1.9 to 2.6 L/min/m2, p less than 0.001). Pulmonary artery wedge pressures fell significantly (24 to 20 mm Hg, p less than 0.02). Decreases were also noted in mean pulmonary artery pressure (36 to 31 mm Hg, p less than 0.02), aortic diastolic pressure (71 to 65 mm Hg, p less than 0.05), systemic vascular resistance (1782 to 1201 dynes. sec. cm-5, p less than 0.001), and pulmonary vascular resistance (265 to 175 dynes.sec.cm-5, less than 0.001). Systolic and mean aortic pressure and heart rate showed no significant change from control. Hemodynamic effects persisted for 5 hours. Pirbuterol was clinically well tolerated. The mechanism of action is unclear at this time, but both inotropic and vasodilator effects are possible. Pirbuterol orally has a marked and prolonged salutary hemodynamic effect and offers promise in CHF treatment.

Systemic and pulmonary hemodynamic effects of saralasin infusion in hypertension. Predictability of plasma renin status from hemodynamic changes

Hemodynamic measurements were obtained before and after 30 minutes of saralasin infusion in 26 fasting adults with hypertension (25 men and 1 woman). Nine showed a depressor response with a decrease in mean intaarterial pressure greater than 20 mm Hg. Ten were nonresponders and seven had an agonistic response with an increase in mean arterial pressure of greater than 10 mm Hg. Heart rate, pulmonary arterial and wedge pressures and pulmonary vascular resistance were nearly identical in the three groups and remained unchanged. Cardiac index decreased from a mean of 2.76 +/- 0.14 (standard error of the mean) to 2.48 +/- 0.1 liters/min per m2 in the nonresponders (P less than 0.02) but remained unchanged in the groups with a depressor or an agonistic response. The mean systemic vascular resistance decreased from 2,406 +/- 303 to 1,839 +/- 265 dynes sec/cm5 in the group with a depressor response (P less than 0.001) and increased in nonresponders (less than 0.02) and those with an agonistic response (P less than 0.01). However, regardless of the response of mean arterial pressure, systemic vascular resistance decreased only in the 10 patients with a plasma renin activity greater than 5 ng/ml per hour (8 from the depressor response group and 1 each from the nonresponse and agonistic response groups). It is concluded that (1) classification based soley on the response of aterial pressure to saralasin ignores important hemodynamic changes; (2) the response of cardiac index--no change in the patients with a depressor response and a reduction in nonresponders--suggests that endogenous angiotension II supports cardiac output in these groups; (3) a decrease in systemic vascular resistance is better than a decrease in mean arteiral pressure as a predictor of the status of the plasma renin activity; and (4) lack of change in pulmonary vascular resistance suggests that endogenous angiotension II plays an insignificant role in maintaining the resistance of the pulmonary vasculature.

Comparative hemodynamic effects of inotropic and vasodilator drugs in severe heart failure

In 12 patients with severe congestive heart failure (CHF) due to ischemic heart disease or nonischemic cardiomyopathy the hemodynamic response to intravenous infusion of sodium nitroprusside (N) was compared to that of dobutamine (D) 10 microgram/kg/min. D and N produced comparable increases in cardiac output (CO) (2.8 to 5.8 L/min and 2.9 to 5.0 L/min, respectively), but, compared to N, D caused a higher arterial pressure (99.3 vs 86.2 mm Hg, P less than 0.01) and heart rate (102.5 vs 95.3, P less than 0.05) and less reduction in pulmonary wedge pressure (PWP) (28.9 to 20.2 mm Hg vs 29.1 to 16.6 mm Hg, P less than 0.05). In five additional patients N and D were studied separately and then were infused together. The combination resulted in a higher CO, lower PWP and greater reduction in systemic and pulmonary vascular resistances than either drug alone. Brachial arterial infusion of nitroprusside produced prominent forearm vasodilation in a dose less than 10% of the systemic dose, whereas vasodilation with dobutamine was only modest even when 50% of the systemic dose was infused. Therefore, potent inotropic and vasodilator drugs produce similar and additive augmentation to left ventricular performance in heart failure. Reduction in vascular resistance with dobutamine probably is largely of reflex origin, but the vasodilation itself may be an important determinant of the rise in cardiac output.

Comparison of dobutamine and dopamine in treatment of severe heart failure

The haemodynamic effects of dobutamine, a new synthetic catecholamine, were studied in 12 patients with severe congestive heart failure and compared with those of dopamine in 10 clinically similar patients. Dobutamine produced a distinct increase in cardiac index, while lowering left ventricular end-diastolic pressure and leaving mean aortic pressure unchanged. Dopamine also significantly improved cardiac index, but at the expense of a greater increase in heart rate than occurred with dobutamine. Dopamine was ineffective in lowering left ventricular end-diastolic pressure, but increased mean aortic pressure. We conclude that dobutamine is an effective, positive inotropic agent in patients with severe congestive heart failure. Because it has comparatively little effect on heart rate and aortic pressure, both major determinants of myocardial oxygen consumption, it may be of special value in patients with the low output syndrome associated with coronary heart disease.

Hemodynamic effect of dobutamine in patients with severe heart failure

Dobutamine, a derivative of dopamine, was infused at a rate of 10 mug/kg per min in 15 patients with severe congestive heart failure. Cardiac output increased from an average of 3.1 to 5.6 liters/min (P less than 0.001) with no change in mean arterial pressure (93.3 to 98.2 mm Hg) and only a slight increase in heart rate (98.5 to 105.2 beats/min) (P less than 0.02). Pulmonary wedge pressure was decreased from an average of 27.4 to 21.1 mm Hg (P less than 0.001). In seven patients a dose of 5 mug/kg per min also produced a significant increase in cardiac output but the effect was less than with the 10 mug/kg per min dose. No side effects were observed during the infusion. Dobutamine therefore is a potent inotropic drug with limited chronotropic and peripheral vascular effects and deserves therapeutic trial in the short-term management of low output heart failure.

Systemic hemodynamic and myocardial metabolic effects of isoproterenol and angiotensin after open-heart surgery

Cardiovascular dynamics and metabolism after open heart surgery were studied in 10 patients before and after infusion of angiotensin and isoproterenol. Patients with rheumatic mitral disease showed marked lowering of cardiac index with elevation of systemic vascular resistance in the control state while those with aortic disease demonstrated less depression of cardiac index and normal resistance. The group with mitral disease also showed lower coronary blood flow and much higher coronary vascular resistance than the aortic patients. Angiotensin caused further depression of cardiac index and marked increase in pressure work. Isoproterenol augmented cardiac index but did not affect pressure work significantly. Both agents increased oxygen consumption significantly by increment in coronary flow (isoproterenol) or by widening of myocardial oxygen extraction (angiotensin). Isoproterenol is favored over angiotensin in low output states after cardiac surgery as a means of meeting oxygen demands as well as the response of cardiac index.

Mechanism of pulsus paradoxus in clinical shock

An inspiratory fall in systolic arterial pressure of more than 10 mm Hg (pulsus paradoxus) was noted in 30 of 61 patients with shock. Inspiratory right atrial pressures and total blood volumes were significantly lower in patients with pulsus paradoxus. Rapid infusion of dextran in 22 patients usually was effective in reversing the exaggerated inspiratory fall in systolic pressure. Total peripheral vascular resistance tended to be higher in the patients with pulsus paradoxus and administration of vasoconsrictor drugs often accentuated the respirator pressure variation. Respiratory effects on blood flow in the aorta, pulmonary artery, and venae cavae were studied in anesthetized, closed-chest dogs. In the control state, pulmonary arterial flow increased during inspiration but aortic flow remained nearly constant. After hemorrhage a sharp inspiratory fall in aortic flow was associated with decreased central blood volume and attenuation of the usual inspiratory increase in venae caval and pulmonary arterial flows. The respiratory changes in aortic flow after hemorrhage could be attributed both to depletion of the pulmonary reservoir and to alterations in pulmonary inflow related to changes in systemic venous return. These data indicate that blood volume depletion may precipitate pulsus paradoxus both in the anesthetized dog and in the critically ill patient. The occurrence of pulsus paradoxus may aid in the clinical recognition of the common syndrome of occult hypovolemia in patients with shock in the absence of signs of blood loss.

Studies in clinical shock and hypotension. V. Hemodynamic effects of dextran

Thirty-one patients with nonhemorrhagic shock or hypotension of diverse etiologies accompanied by low cardiac output and normal or low right atrial pressure were given a rapid infusion of dextran. Cardiac output returned to normal in 20 patients and shock or hypotension was corrected in 16.

In 10 patients with evidence of vasoconstriction and normal cardiac function, dextran reversed the circulatory abnormality, returning blood pressure, cardiac output, and peripheral vascular resistance to normal. Twelve patients with hypotension without evidence of reflex vasoconstriction were improved by dextran but the hypotension persisted occasionally. In nine patients, dextran revealed heart failure as manifested by a precipitous rise in right atrial pressure without much increase in cardiac output. Control hemodynamic observations and the response to dextran could not necessarily be predicted from the nature of the disease which precipitated the shock.

The efficacy of a rapid infusion of low molecular weight or clinical dextran associated with its freedom from significant toxicity should make it the treatment of choice in non-hemorrhagic shock of any cause associated with normal central venous pressure.