Direct vascular effects of furosemide in humans

Vasodilators for Acute Heart Failure - A Systematic Review with Meta-Analysis

BACKGROUND

Acute heart failure is a public health concern. This study systematically reviewed randomized clinical trials (RCTs) to evaluate vasodilators in acute heart failure.

METHODS

The search was conducted across the databases of Medline, Embase, Latin American and the Caribbean Literature on Health Sciences, Web of Science, and the Cochrane Central Register of Controlled Trials. Inclusion criteria consisted of RCTs that compared vasodilators versus standard care, placebo, or cointerventions. The primary outcome was all-cause mortality; secondary outcomes were serious adverse events (SAEs), tracheal intubation, and length of hospital stay. Risk of bias was assessed in all trials.

RESULTS

The study included 46 RCTs that enrolled 28,374 patients with acute heart failure. Vasodilators did not reduce the risk of all-cause mortality (risk ratio, 0.95; 95% confidence interval [CI], 0.87 to 1.04; I2=9.51%; P=0.26). No evidence of a difference was seen in the risk of SAEs (risk ratio, 1.01; 95% CI, 0.97 to 1.05; I2=0.94%) or length of hospital stay (mean difference, -0.10; 95% CI, -0.28 to 0.08; I2=69.84%). Vasodilator use was associated with a lower risk of tracheal intubation (risk ratio, 0.54; 95% CI, 0.30 to 0.99; I2=51.96%) compared with no receipt of vasodilators.

CONCLUSIONS

In this systematic review with meta-analysis of patients with acute heart failure, vasodilators did not reduce all-cause mortality.

Clinical Review of Hypertensive Acute Heart Failure

Although acute heart failure (AHF) is a common disease associated with significant symptoms, morbidity and mortality, the diagnosis, risk stratification and treatment of patients with hypertensive acute heart failure (H-AHF) still remain a challenge in modern medicine. Despite great progress in diagnostic and therapeutic modalities, this disease is still accompanied by a high rate of both in-hospital (from 3.8% to 11%) and one-year (from 20% to 36%) mortality. Considering the high rate of rehospitalization (22% to 30% in the first three months), the treatment of this disease represents a major financial blow to the health system of each country. This disease is characterized by heterogeneity in precipitating factors, clinical presentation, therapeutic modalities and prognosis. Since heart decompensation usually occurs quickly (within a few hours) in patients with H-AHF, establishing a rapid diagnosis is of vital importance. In addition to establishing the diagnosis of heart failure itself, it is necessary to see the underlying cause that led to it, especially if it is de novo heart failure. Given that hypertension is a precipitating factor of AHF and in up to 11% of AHF patients, strict control of arterial blood pressure is necessary until target values are reached in order to prevent the occurrence of H-AHF, which is still accompanied by a high rate of both early and long-term mortality.

Vasovagal Syncope and Pulseless Electrical Activity Cardiac Arrest in Patients With Immunoglobulin Light Chain Cardiac Amyloidosis: A Case Series

Immunoglobulin light chain (AL) amyloidosis may lead to amyloid fibril deposition into peripheral and autonomic nerves, resulting in resting and orthostatic hypotension. While most patients die from progressive heart failure, the most commonly proposed cardiac rhythm associated with sudden death is pulseless electrical activity (PEA). Herein, we describe four patients with severe AL cardiac amyloidosis who had witnessed cardiac arrest with pulseless electrical activity as a result of vasovagal syncope. Healthcare providers should be aware of severe autonomic dysfunction in cardiac amyloidosis and the potential for an abnormal vasovagal response leading to syncope or death.

Advanced Hemodynamic Monitoring Allows Recognition of Early Response Patterns to Diuresis in Congestive Heart Failure Patients

There are no clear guidelines for diuretic administration in heart failure (HF), and reliable markers are needed to tailor treatment. Continuous monitoring of multiple advanced physiological parameters during diuresis may allow better differentiation of patients into subgroups according to their responses. In this study, 29 HF patients were monitored during outpatient intravenous diuresis, using a noninvasive wearable multi-parameter monitor. Analysis of changes in these parameters during the course of diuresis aimed to recognize subgroups with different response patterns. Parameters did not change significantly, however, subgroup analysis of the last quartile of treatment showed significant differences in cardiac output, cardiac index, stroke volume, pulse rate, and systemic vascular resistance according to gender, and in systolic blood pressure according to habitus. Changes in the last quartile could be differentiated using k-means, a technique of unsupervised machine learning. Moreover, patients' responses could be best clustered into four groups. Analysis of baseline parameters showed that two of the clusters differed by baseline parameters, body mass index, and diabetes status. To conclude, we show that physiological changes during diuresis in HF patients can be categorized into subgroups sharing similar response trends, making noninvasive monitoring a potential key to personalized treatment in HF.

Pharmacological treatment of cardiogenic shock - A state of the art review

Cardiogenic shock is a clinical syndrome of impaired tissue perfusion caused by primary cardiac dysfunction and inadequate cardiac output. It represents one of the most lethal clinical conditions in intensive care medicine with mortality >40%. Management of different clinical presentations of cardiogenic shock includes guidance of cardiac preload, afterload, heart rate and contractility by differential pharmacological modulation of volume, systemic and pulmonary vascular resistance and cardiac output besides reversing the triggering cause. Data from large registries and randomized controlled trials on optimal diagnostic guidance as well as choice of pharmacological agents has accrued significantly in recent years. This state-of-the-art review summarizes the basic concepts of cardiogenic shock, the diagnostic work-up and currently available evidence and guideline recommendations on pharmacological treatment of cardiogenic shock.

Prophylactic furosemide to prevent transfusion-associated circulatory overload: a randomized controlled study in rats

Transfusion-associated circulatory overload (TACO) is the leading cause of transfusion related morbidity and mortality. The only treatment is empirical use of furosemide. Our aim was to investigate if furosemide can prevent TACO. A randomized controlled trial was performed using a previously validated two-hit rat model for TACO. Volume incompliance was induced (first hit) in anemic, anesthetized Lewis rats. Rats were randomized to placebo, low-dose (5 mg kg-1) or high-dose (15 mg kg-1) furosemide-administered prior to transfusion (second-hit) and divided over two doses. Primary outcome was change in left-ventricular end-diastolic pressure (∆LVEDP) pre- compared to post-transfusion. Secondary outcomes included changes in preload, afterload, contractility and systemic vascular resistance, as well as pulmonary outcomes. Furosemide treated animals had a significantly lower ∆LVEDP compared to placebo (p = 0.041), a dose-response effect was observed. ∆LVEDP in placebo was median + 8.7 mmHg (IQR 5.9-11), + 3.9 (2.8-5.6) in the low-dose and 1.9 (- 0.6 to 5.6) in the high-dose group. The effect of furosemide became apparent after 15 min. While urine output was significantly higher in furosemide treated animals (p = 0.03), there were no significant changes in preload, afterload, contractility or systemic vascular resistance. Furosemide rapidly and dose-dependently decreases the rise in hydrostatic pulmonary pressure following transfusion, essential for preventing TACO.

South African medicinal plants displaying angiotensin-converting enzyme inhibition: Potential use in the management of preeclampsia

In resource-limited settings, such as South Africa, hypertensive disorders of pregnancy such as preeclampsia, is the most common direct cause of maternal deaths. Current management strategies of preeclampsia primarily involve the use of pharmaceutical drugs, which are frequently associated with undesirable side-effects. Moreover, these drugs are often not easily accessible due to financial and economic constraints. Consequently, many patients rely on traditional medicine obtained from medicinal plants to manage health-related conditions. Angiotensin-converting enzyme inhibitors are widely used drugs for the management of preeclampsia. This narrative review aims to highlight the use of indigenous medicinal plants from South Africa with Angiotensin-converting enzyme inhibitory activity whilst also evaluating their potential use in the treatment of hypertension in pregnancy. This information will influence traditional healers and sangomas in their patient management. Furthermore, the antihypertensive potential of these plants will be unraveled thus facilitating the development of new naturally occurring pharmaceutical products to reduce maternal and neonatal mortality and morbidity.

Preload Dependence Fails to Predict Hemodynamic Instability During a Fluid Removal Challenge in Children

OBJECTIVES

Fluid overload increases morbidity and mortality in PICU patients. Active fluid removal improves the prognosis but may worsen organ dysfunction. Preload dependence in adults does predict hemodynamic instability induced by a fluid removal challenge (FRC). We sought to investigate the diagnostic accuracy of dynamic and static markers of preload in predicting hemodynamic instability and reduction of stroke volume during an FRC in children. We followed the Standards for Reporting of Diagnostic Accuracy statement to design conduct and report this study.

DESIGN

Prospective noninterventional cohort study.

SETTINGS

From June 2017 to April 2019 in a pediatric cardiac ICU in a tertiary hospital.

PATIENTS

Patients 8 years old or younger, with symptoms of fluid overload after cardiac surgery, were studied.

INTERVENTIONS

We confirmed preload dependence by echocardiography before and during a calibrated abdominal compression test. We then performed a challenge to remove 10-mL/kg fluid in less than 120 minutes with an infusion of diuretics. Hemodynamic instability was defined as a decrease of 10% of mean arterial pressure.

MEASUREMENT AND MAIN RESULTS

We compared patients showing hemodynamic instability with patients remaining stable, and we built receiver operative characteristic (ROC) curves. Among 58 patients studied, 10 showed hemodynamic instability. The area under the ROC curve was 0.55 for the preload dependence test (95% CI, 0.34-0.75). Using a threshold of 10% increase in stroke volume index (SVi) during calibrated abdominal compression, the specificity was 0.30 (95% CI, 0.00-0.60) and the sensitivity was 0.77 (95% CI, 0.65-0.88). Mean arterial pressure variation and SVi variation were not correlated during fluid removal; r = 0.19; 95% CI -0.07 to 0.43; p = 0.139.

CONCLUSIONS

Preload dependence is not accurate to predict hemodynamic instability during an FRC. Our data do not support a reduction in intravascular volume being mainly responsible for the reduction in arterial pressure during an FRC in children.

Pulmonary Edema in COVID-19 Patients: Mechanisms and Treatment Potential

COVID-19 mortality is primarily driven by abnormal alveolar fluid metabolism of the lung, leading to fluid accumulation in the alveolar airspace. This condition is generally referred to as pulmonary edema and is a direct consequence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. There are multiple potential mechanisms leading to pulmonary edema in severe Coronavirus Disease (COVID-19) patients and understanding of those mechanisms may enable proper management of this condition. Here, we provide a perspective on abnormal lung humoral metabolism of pulmonary edema in COVID-19 patients, review the mechanisms by which pulmonary edema may be induced in COVID-19 patients, and propose putative drug targets that may be of use in treating COVID-19. Among the currently pursued therapeutic strategies against COVID-19, little attention has been paid to abnormal lung humoral metabolism. Perplexingly, successful balance of lung humoral metabolism may lead to the reduction of the number of COVID-19 death limiting the possibility of healthcare services with insufficient capacity to provide ventilator-assisted respiration.

Differences in pharmacological property between combined therapy of the vasopressin V2-receptor antagonist tolvaptan plus furosemide and monotherapy of furosemide in patients with hospitalized heart failure

BACKGROUND

Tolvaptan has been shown to improve congestion in heart failure patients. The purpose of this study was to evaluate the pharmacology and clinical efficacy of combined tolvaptan and furosemide therapy.

METHODS

This study included 40 patients with systemic volume overload who were hospitalized for heart failure. Patients who showed no improvement in the condition after receiving 20 mg intravenous furosemide were included and were randomly selected to receive tolvaptan as an add-on to furosemide or to receive an increased dose of furosemide. We evaluated the bioelectrical impedance analyzer parameters, the parameters of the inferior vena cava using echocardiography, vital signs, body weight, urine output, and laboratory data for 5 days.

RESULTS

In the changes from baseline between intracellular water volume (ICW) and extracellular water volume (ECW) after additional use of tolvaptan or furosemide from Day 1 to Day 5, there were no significant differences observed between ICW and ECW over 5 days in the tolvaptan + furosemide group, although differences were found in the furosemide group from Day 2 onward. Changes in the respiratory collapse of inferior vena cava increased significantly, and systolic blood pressure decreased significantly only in the furosemide group.

CONCLUSIONS

The present study clearly demonstrates that combined therapy with tolvaptan and furosemide removed excess ICW and ECW to an equal extent, while furosemide alone primarily removed ECW, including intravascular water.

Independent and interactive effects of incremental heat strain, orthostatic stress, and mild hypohydration on cerebral perfusion

The purpose of this study was to identify the dose-dependent effects of heat strain and orthostasis [via lower body negative pressure (LBNP)], with and without mild hypohydration, on systemic function and cerebral perfusion. Eleven men (means ± SD: 27 ± 7 y; body mass 77 ± 6 kg), resting supine in a water-perfused suit, underwent progressive passive heating [0.5°C increments in core temperature (T_c; esophageal to +2.0°C)] while euhydrated (EUH) or hypohydrated (HYPO; 1.5-2% body mass deficit). At each thermal state, mean cerebral artery blood velocity (MCAv_mean; transcranial Doppler), partial pressure of end-tidal carbon dioxide ([Formula: see text]), heart rate (HR) and mean arterial blood pressure (MAP; photoplethysmography) were measured continuously during LBNP (0, -15, -30, and -45 mmHg). Four subjects became intolerant before +2.0°C T_c, unrelated to hydration status. Without LBNP, decreases in [Formula: see text] accounted fully for reductions in MCAv_mean across all T_c. With LBNP at heat tolerance (+1.5 or +2.0°C), [Formula: see text] accounted for 69 ± 25% of the change in MCAv_mean. The HYPO condition did not affect MCAv_mean or any cardiovascular variables during combined LBNP and passive heat stress (all P > 0.13). These findings indicate that hypocapnia accounted fully for the reduction in MCAv_mean when passively heat stressed in the absence of LBNP and for two- thirds of the reduction when at heat tolerance combined with LBNP. Furthermore, when elevations in T_c are matched, mild hypohydration does not influence cerebrovascular or cardiovascular responses to LBNP, even when stressed by a combination of hyperthermia and LBNP.

Orthostatic hypotension: prevalence and associated risk factors among the ambulatory elderly in an Asian population

INTRODUCTION

The prevalence of orthostatic hypotension (OH) among the elderly population in Singapore, as defined by a decline in blood pressure upon a change in position, is not well-established. Studies associate OH with clinically significant outcomes such as falls. This study aims to determine the prevalence of OH among elderly patients attending a public primary care clinic (polyclinic) for chronic disease management, and examine the relationships between postulated risk factors and OH.

METHODS

Patients aged ≥ 65 years attending a typical polyclinic in Geylang were identified and targeted for recruitment at the study site. A questionnaire on symptoms and postulated risk factors was administered, followed by supine and standing blood pressure measurements. Cross-sectional analysis was performed with independent sample t-test for continuous data and chi-square test for categorical data. Prevalence rate ratios with 95% confidence interval were calculated for the latter.

RESULTS

A total of 364 multiethnic patients participated in the study. The prevalence of OH was 11.0%. Older age, comorbidities such as cardiac failure and kidney disease, being physically inactive at work, fatigue, self-reported dizziness in the past year, and the use of loop diuretics were found to be significantly associated with OH.

CONCLUSION

About one in ten elderly patients at a local polyclinic was affected by OH, which was associated with multiple factors. Some of these factors are modifiable and can be addressed to reduce the incidence of OH.

Inhibition of ROMK blocks macula densa tubuloglomerular feedback yet causes renal vasoconstriction in anesthetized rats

The Na⁺-K⁺-2Cl^- cotransporter (NKCC2) on the loop of Henle is the site of action of furosemide. Because outer medullary potassium channel (ROMK) inhibitors prevent reabsorption by NKCC2, we tested the hypothesis that ROMK inhibition with a novel selective ROMK inhibitor (compound C) blocks tubuloglomerular feedback (TGF) and reduces vascular resistance. Loop perfusion of either ROMK inhibitor or furosemide caused dose-dependent blunting of TGF, but the response to furosemide was 10-fold more sensitive (IC₅₀ = 10^-6 M for furosemide and IC₅₀ = 10^-5 M for compound C). During systemic infusion, both diuretics inhibited TGF, but ROMK inhibitor was 10-fold more sensitive (compound C: 63% inhibition; furosemide: 32% inhibition). Despite blockade of TGF, 1 h of constant systemic infusion of both diuretics reduced the glomerular filtration rate (GFR) and renal blood flow (RBF) by 40-60% and increased renal vascular resistance (RVR) by 100-200%. Neither diuretic altered blood pressure or hematocrit. Proximal tubule hydrostatic pressures (P_PT) increased transiently with both diuretics (compound C: 56% increase; furosemide: 70% increase) but returned to baseline. ROMK inhibitor caused more natriuresis (3,400 vs. 1,600% increase) and calciuresis (1,200 vs. 800% increase) but less kaliuresis (33 vs. 167% increase) than furosemide. In conclusion, blockade of ROMK or Na⁺-K⁺-2Cl^- transport inhibits TGF yet increases renal vascular resistance. The renal vasoconstriction was independent of volume depletion, blood pressure, TGF, or P_PT.

The Effects of Bumetanide on Human Umbilical Artery Contractions

The authors investigate the effect of bumetan ide, an inhibitor of NKCC1 and a loop diuretic, on the tone of human umbilical artery (HUA). Rings of HUA (n = 35) from vaginal deliveries were suspended for isometric tension recordings in organ baths. Cumulative concentration-response curves to serotonin, histamine, and KCl were performed in the absence (control) or in the presence of bumetanide. The relaxant effect of bumetanide was also evaluated in serotonin- and histamine-induced contractions. Bumetanide inhibited HUA tone in serotonin- and histamine-induced contractions with significant changes in the potency (pD(2)) and maximum contractile response (E(max)) values. However, only pD( 2) values for KCl-induced contraction significantly changed in the presence of bumetanide. Bumetanide caused concentration-dependent and sustained relaxations in serotonin-induced contraction; however, there was refractoriness in histamine-induced contraction. These findings raise the possibility that NKCC1 may play a role in the regulation of the umbilical artery tone.

Everything we always wanted to know about furosemide but were afraid to ask

Furosemide is a widely used, potent natriuretic drug, which inhibits the Na(+)-K(+)-2Cl(-) cotransporter (NKCC)-2 in the ascending limb of the loop of Henle applied to reduce extracellular fluid volume expansion in heart and kidney disease. Undesirable consequences of furosemide, such as worsening of kidney function and unpredictable effects on sodium balance, led to this critical evaluation of how inhibition of NKCC affects renal and cardiovascular physiology. This evaluation reveals important knowledge gaps, involving furosemide as a drug, the function of NKCC2 (and NKCC1), and renal and systemic indirect effects of NKCC inhibition. Regarding renal effects, renal blood flow and glomerular filtration rate could become compromised by activation of tubuloglomerular feedback or by renin release, particularly if renal function is already compromised. Modulation of the intrarenal renin angiotensin system, however, is ill-defined. Regarding systemic effects, vasodilation followed by nonspecific NKCC inhibition and changes in venous compliance are not well understood. Repetitive administration of furosemide induces short-term (braking phenomenon, acute diuretic resistance) and long-term (chronic diuretic resistance) adaptations, of which the mechanisms are not well known. Modulation of NKCC2 expression and activity in kidney and heart failure is ill-defined. Lastly, furosemide's effects on cutaneous sodium stores and on uric acid levels could be beneficial or detrimental. Concluding, a considerable knowledge gap is identified regarding a potent drug with a relatively specific renal target, NKCC2, and renal and systemic actions. Resolving these questions would increase the understanding of NKCCs and their actions and improve rational use of furosemide in pathophysiology of fluid volume expansion.

New insights into carbonic anhydrase inhibition, vasodilation, and treatment of hypertensive-related diseases

Carbonic anhydrase (CA) and its inhibitors are relevant to many physiological processes and diseases. The enzyme is differentially expressed throughout the body, in concentration and subcellular location, and as 13 catalytically active isoforms. Blood vessels contain small amounts of CA, but the enzyme's role in vascular physiology and blood pressure regulation is uncertain. However, considerable recent evidence points to vasodilation by CA inhibitors. CA inhibition in vascular smooth muscle, endothelium, heart, blood cells, and nervous system could all contribute. It is equally plausible that other targets besides CA for all known CA inhibitors may account for their vascular effects. I will review this knowledge and important remaining gaps relating to treatment of hypertensive-related diseases with potent sulfonamide inhibitors, such as acetazolamide; but also the possibility that CA inhibition by thiazides and loop diuretics, although generally weaker, may have antihypertensive effects beyond their inhibition of renal sodium transporters.

Inferior vena cava diameter change after intravenous furosemide in patients diagnosed with acute decompensated heart failure

PURPOSE

Measurement of the inferior vena cava (IVC) diameters may improve decision-making for patients hospitalized with acute decompensated heart failure. Nevertheless, little is known about how the IVC is affected by loop diuretics. We sought to determine if bolus infusions of intravenous furosemide affect IVC diameters measured by hand-carried ultrasonography.

METHODS

We conducted a prospective cohort study at a public teaching hospital from September 2009 through June 2010. Physician investigators performed IVC ultrasonography on a convenience sample of 70 hospitalized adults who were prescribed intravenous furosemide for the diagnosis of acute decompensated heart failure.

RESULTS

Participants' median baseline IVC diameter was 2.38 cm (interquartile range, 1.91-2.55 cm). At 1-2 hours after furosemide, IVC diameters decreased an average of 0.21 cm (95% CI, 0.13-0.29 cm) and remained significantly below baseline at 2-3 hours after furosemide by an average of 0.15 cm (95% CI, 0.07-0.22 cm).

CONCLUSIONS

IVC diameters of adults diagnosed with acute decompensated heart failure become measurably smaller after single doses of intravenous furosemide. Whether this represents a true change in volume status has not been studied.

Pulmonary Oedema-Therapeutic Targets

Pulmonary oedema (PO) is a common manifestation of acute heart failure (AHF) and is associated with a high-acuity presentation and with poor in-hospital outcomes. The clinical picture of PO is dominated by signs of pulmonary congestion, and its pathogenesis has been attributed predominantly to an imbalance in Starling forces across the alveolar-capillary barrier. However, recent studies have demonstrated that PO formation and resolution is critically regulated by active endothelial and alveolar signalling. PO represents a medical emergency and treatment should be individually tailored to the urgency of the presentation and acute haemodynamic characteristics. Although, the majority of patients admitted with PO rapidly improve as result of conventional intravenous (IV) therapies, treatment of PO remains largely opinion based as there is a general lack of good evidence to guide therapy. Furthermore, none of these therapies showed simultaneous benefit for symptomatic relief, haemodynamic improvement, increased survival and end-organ protection. Future research is required to develop innovative pharmacotherapies capable of relieving congestion while simultaneously preventing end-organ damage.

Arsenic exposure decreases rhythmic contractions of vascular tone through sodium transporters and K+ channels

Arsenic-contaminated drinking water is a public health problem in countries such as Taiwan, Bangladesh, United States, Mexico, Argentina, and Chile. The chronic ingestion of arsenic-contaminated drinking water increases the risk for ischemic heart disease, cerebrovascular disease, and prevalence of hypertension. Although toxic arsenic effects are controversial, there is evidence that a high concentration of arsenic may induce hypertension through increase in vascular tone and resistance. Vascular tone is regulated by the rhythmic contractions of the blood vessels, generated by calcium oscillations in the cytosol of vascular smooth muscle cells. To regulate the cytosolic calcium oscillations, the membrane oscillator model involves the participation of Ca²⁺ channels, calcium-activated K⁺ channels, Na⁺/Ca²⁺ exchange, plasma membrane Ca²⁺-ATPase, and the Na⁺/K⁺-ATPase. However, little is known about the role of K⁺ uptake by sodium transporters [Na⁺/K⁺-ATPase or Na⁺-K⁺-2Cl^- (NKCC1)] on the rhythmic contractions. Vascular rhythmic contractions, or vasomotion are a local mechanism to regulate vascular resistance and blood flow. Since vascular rhythmic contractions of blood vessels are involved in modulating the vascular resistance, the blood flow, and the systemic pressure, we suggest a model explaining the participation of the sodium pump and NKCC1 co-transporter in low dose arsenic exposure effects on vasomotion and vascular dysfunction.

Simplified clinical risk score to predict acute kidney injury after aortic surgery

OBJECTIVE

The authors identified risk factors for acute kidney injury (AKI) defined by risk, injury, failure, loss, end-stage (RIFLE) criteria after aortic surgery with cardiopulmonary bypass and constructed a simplified risk score for the prediction of AKI.

DESIGN

Retrospective and observational.

SETTING

Single large university hospital.

PARTICIPANTS

Patients (737) who underwent aortic surgery with cardiopulmonary bypass between 1997 and 2010.

MAIN RESULTS

Multivariate logistic regression analysis was used to evaluate risk factors. A scoring model was developed in a randomly selected derivation cohort (n = 417), and was validated on the remaining patients. The scoring model was developed with a score based on regression β-coefficient, and was compared with previous indices as measured by the area under the receiver operating characteristic curve (AUC). The incidence of AKI was 29.0%, and 5.8% required renal replacement therapy. Independent risk factors for AKI were age older than 60 years, preoperative glomerular filtration rate <60 mL/min/1.73 m(2), left ventricular ejection fraction <55%, operation time >7 hours, intraoperative urine output <0.5 mL/kg/h, and intraoperative furosemide use. The authors made a score by weighting them at 1 point each. The risk score was valid in predicting AKI, and the AUC was 0.74 [95% confidence interval (CI): 0.69 to 0.79], which was similar to that in the validation cohort: 0.74 (95% CI: 0.69 to 0.80; p = 0.97). The risk-scoring model showed a better performance compared with previously reported indices.

CONCLUSIONS

The model would provide a simplified clinical score stratifying the risk of postoperative AKI in patients undergoing aortic surgery.

Chloride transport-driven alveolar fluid secretion is a major contributor to cardiogenic lung edema

Alveolar fluid clearance driven by active epithelial Na(+) and secondary Cl(-) absorption counteracts edema formation in the intact lung. Recently, we showed that impairment of alveolar fluid clearance because of inhibition of epithelial Na(+) channels (ENaCs) promotes cardiogenic lung edema. Concomitantly, we observed a reversal of alveolar fluid clearance, suggesting that reversed transepithelial ion transport may promote lung edema by driving active alveolar fluid secretion. We, therefore, hypothesized that alveolar ion and fluid secretion may constitute a pathomechanism in lung edema and aimed to identify underlying molecular pathways. In isolated perfused lungs, alveolar fluid clearance and secretion were determined by a double-indicator dilution technique. Transepithelial Cl(-) secretion and alveolar Cl(-) influx were quantified by radionuclide tracing and alveolar Cl(-) imaging, respectively. Elevated hydrostatic pressure induced ouabain-sensitive alveolar fluid secretion that coincided with transepithelial Cl(-) secretion and alveolar Cl(-) influx. Inhibition of either cystic fibrosis transmembrane conductance regulator (CFTR) or Na(+)-K(+)-Cl(-) cotransporters (NKCC) blocked alveolar fluid secretion, and lungs of CFTR(-/-) mice were protected from hydrostatic edema. Inhibition of ENaC by amiloride reproduced alveolar fluid and Cl(-) secretion that were again CFTR-, NKCC-, and Na(+)-K(+)-ATPase-dependent. Our findings show a reversal of transepithelial Cl(-) and fluid flux from absorptive to secretory mode at hydrostatic stress. Alveolar Cl(-) and fluid secretion are triggered by ENaC inhibition and mediated by NKCC and CFTR. Our results characterize an innovative mechanism of cardiogenic edema formation and identify NKCC1 as a unique therapeutic target in cardiogenic lung edema.

Non-cardiogenic pulmonary edema complicating electroconvulsive therapy: short review of the pathophysiology and diagnostic approach

Acute pulmonary edema complicating electroconvulsive therapy is an extremely uncommon event that has rarely been described in the literature. Different theories, including one suggesting a cardiogenic component, have been proposed to explain its genesis. The present report describes a classic presentation of this condition with review of its potential mechanisms and diagnostic approach. After successful completion of a session of electroconvulsive therapy, a 42-year-old woman with major depressive disorder developed acute systemic high blood pressure, shortness of breath, and hemoptysis. A chest radiograph demonstrated diffuse bilateral pulmonary infiltrates. Initially cardiogenic pulmonary edema was presumed, but an extensive diagnostic work-up demonstrated normal systolic and diastolic left ventricular function, and with only supportive measures, a complete clinical and radiographic recovery was achieved within 48 hours. The present case does not support any cardiogenic mechanism in the genesis of this condition.

Furosemide is associated with acute kidney injury in critically ill patients

Acute kidney injury (AKI) is common in critically ill patients. Diuretics are used without any evidence demonstrating a beneficial effect on renal function. The objective of the present study is to determine the incidence of AKI in an intensive care unit (ICU) and if there is an association between the use of furosemide and the development of AKI. The study involved a hospital cohort in which 344 patients were consecutively enrolled from January 2010 to January 2011. A total of 132 patients (75 females and 57 males, average age 64 years) remained for analysis. Most exclusions were related to ICU discharge in the first 24 h. Laboratory, sociodemographic and clinical data were collected until the development of AKI, medical discharge or patient death. The incidence of AKI was 55% (95%CI = 46-64). The predictors of AKI found by univariate analysis were septic shock: OR = 3.12, 95%CI = 1.36-7.14; use of furosemide: OR = 3.27, 95%CI = 1.57-6.80, and age: OR = 1.02, 95%CI = 1.00-1.04. Analysis of the subgroup of patients with septic shock showed that the odds ratio of furosemide was 5.5 (95%CI = 1.16-26.02) for development of AKI. Age, use of furosemide, and septic shock were predictors of AKI in critically ill patients. Use of furosemide in the subgroup of patients with sepsis/septic shock increased (68.4%) the chance of development of AKI when compared to the sample as a whole (43.9%)

Effects of dehydration on cerebrovascular control during standing after heavy resistance exercise

We tested the hypothesis that dehydration exacerbates reductions of middle cerebral artery blood velocity (MCAv) and alters cerebrovascular control during standing after heavy resistance exercise. Ten males participated in two trials under 1) euhydration (EUH) and 2) dehydration (DEH; fluid restriction + 40 mg furosemide). We recorded finger photoplethysmographic arterial pressure and MCAv (transcranial Doppler) during 10 min of standing immediately after high-intensity leg press exercise. Symptoms (e.g., lightheadedness) were ranked by subjects during standing (1-5 scale). Low-frequency (LF) oscillations of mean arterial pressure (MAP) and mean MCAv were calculated as indicators of cerebrovascular control. DEH reduced plasma volume by 11% (P = 0.002; calculated from hemoglobin and hematocrit). During the first 30 s of standing after exercise, subjects reported greater symptoms during DEH vs. EUH (P = 0.05), but these were mild and resolved at 60 s. While MAP decreased similarly between conditions immediately after standing, MCAv decreased more with DEH than EUH (P = 0.02). With prolonged standing under DEH, mean MCAv remained below baseline (P ≤ 0.01), and below EUH values (P ≤ 0.05). LF oscillations of MAP were higher for DEH at baseline and during the entire 10 min of stand after exercise (P ≤ 0.057), while LF oscillations in mean MCAv were distinguishable only at baseline and 5 min following stand (P = 0.05). Our results suggest that mean MCAv falls below a "symptomatic threshold" in the acute phase of standing after exercise during DEH, although symptoms were mild and transient. During the prolonged phase of standing, increases in LF MAP and mean MCAv oscillations with DEH may help to maintain cerebral perfusion despite absolute MCAv remaining below the symptomatic threshold.

Intravenous high-dose furosemide and hypertonic saline solutions for refractory heart failure and ascites

Several studies have shown the efficacy of hypertonic saline solution infusion in conditions in which regional organ blood flow is impaired. Our group has shown that treatment of patients with diuretic-resistant heart failure with high-dose furosemide plus hypertonic saline is effective and well tolerated, improving symptoms of congestion, reducing plasma levels of markers of neurohormonal and inflammatory activation, decreasing hospital readmission rates, and reducing long-term mortality. The same regimen was shown to be better than repeated paracentesis in patients with cirrhosis and refractory ascites, yielding better control of ascites, pleural effusions, and/or leg edema without an increase of common adverse effects linked to high-dose furosemide such as hepatic encephalopathy.

Randomized placebo controlled trial of furosemide on subjective perception of dyspnoea in patients with pulmonary oedema because of hypertensive crisis

BACKGROUND

To compare the administration of furosemide with placebo on the subjective perception of dyspnoea in patients with acute pulmonary oedema because of hypertensive crisis. Design  Randomized, controlled and double-blinded clinical trial.

SETTING

Municipal emergency medical service system and university-based emergency department.

PARTICIPANTS

Fifty-nine patients with pulmonary oedema because of hypertensive crisis.

INTERVENTIONS

Additional to administration of oxygen, morphine-hydrochloride and urapidil until the systolic blood pressure was below 160mmHg, the patients were randomized to receive furosemide 80mg IV bolus (furosemide group) or saline placebo (placebo group).

MAIN OUTCOME MEASURES

The primary outcome was the subjective perception of dyspnoea as measured with a modified BORG scale at one hour after randomization. Secondary outcome parameters were the subjective perception of dyspnoea of patients as measured with a modified BORG scale and a visual analogue scale at 2, 3 and 6h after randomization of the patient; course of the systolic arterial pressure and peripheral oxygen saturation and lactate at admission and at 6h after admission.

RESULTS

In 25 patients in the furosemide group and in 28 patients in the placebo group, a BORG score could be obtained. There was no statistically significant difference in the severity of dyspnoea at one hour after randomization (P=0·40). The median BORG score at 1h after randomization in the furosemide group was 3 (IQR 2 to 4) compared to 3 (IQR 2 to 7) in the placebo group (P=0·40). Those patients who were randomized to the placebo group needed higher doses of urapidil at 20min after randomization. There were no significant differences in the rate of adverse events, nonfatal cardiac arrests or death between the two groups.

CONCLUSIONS

The subjective perception of dyspnoea in patients with hypertensive pulmonary oedema was not influenced by the application of a loop-diuretic. Therefore, additional furosemide therapy needs to be scrutinized in the therapy of these patients.

Metabolic and toxicological considerations for diuretic therapy in patients with acute heart failure

INTRODUCTION

Diuretics are widely recommended in patients with acute heart failure (AHF). However, loop diuretics predispose patients to electrolyte imbalance and hypovolemia, which in turn leads to neurohormonal activation and worsening renal function (WRF). Unfortunately, despite their widespread use, limited data from randomized clinical trials are available to guide clinicians with the appropriate management of this diuretic therapy.

AREAS COVERED

This review focuses on the current management of diuretic therapy and discusses data supporting the efficacy and safety of loop diuretics in patients with AHF. The authors consider the challenges in performing clinical trials of diuretics in AHF, and describe ongoing clinical trials designed to rigorously evaluate optimal diuretic use in this syndrome. The authors review the current evidence for diuretics and suggest hypothetical bases for their efficacy relying on the complex relationship among diuretics, neurohormonal activation, renal function, fluid and sodium management, and heart failure syndrome.

EXPERT OPINION

Data from several large registries that evaluated diuretic therapy in hospitalized patients with AHF suggest that its efficacy is far from being universal. Further studies are warranted to determine whether high-dose diuretics are responsible for WRF and a higher rate of coexisting renal disease are instead markers of more severe heart failure. The authors believe that monitoring congestion during diuretic therapy in AHF would refine the current approach to AHF treatment. This would allow clinicians to identify high-risk patients and possibly reduce the incidence of complications secondary to fluid management strategies.

Control of cerebral blood velocity with furosemide-induced hypovolemia and upright tilt

The purpose of this study was to test the hypothesis that exacerbated reductions of cerebral blood velocity (CBV) during upright tilt with dehydration are associated with impaired cerebrovascular control. Nine healthy men were tilted head-up (HUT) to 70° for 10 min on two occasions separated by 7 days under euhydration (EUH) and dehydration (DEH; 40 mg of furosemide and water restriction) conditions. Beat-by-beat arterial pressures and CBV were measured during a 5-min supine baseline and during the first (T1) and last (T2) 5 min of HUT. Cerebral autoregulation and arterial baroreflex sensitivity were assessed in the frequency domain with cross-spectral techniques. DEH reduced plasma volume by 10% ( P = 0.008) and supine mean CBV (CBVmean) by 11% ( P = 0.002). Mean arterial pressure (MAP), stroke volume, and baroreflex sensitivity decreased during HUT ( P ≤ 0.002), but absolute reductions were similar between hydration conditions, with the exception of stroke volume, which was lower at T1 during DEH than EUH ( P = 0.04). CBVmean during DEH was lower (7 cm/s) over the course of the entire 10 min of HUT ( P ≤ 0.004) than during EUH. Low-frequency oscillations (0.07-0.2 Hz) of MAP and CBVmean and MAP-CBVmean coherence were higher during DEH than EUH at T1 ( P ≤ 0.02), but not at T2. Our results suggest that increased coherence between arterial pressure and CBV with the combination of DEH and HUT are indicative of altered cerebrovascular control. Increased CBV oscillations with DEH may reflect acute protective mechanisms to ensure adequate cerebral perfusion under conditions of reduced central blood volume.

Changes in estimating echocardiography pulmonary capillary wedge pressure after hypersaline plus furosemide versus furosemide alone in decompensated heart failure

BACKGROUND

The aim of the study was to verify the effects of hypertonic saline solution (HSS) plus a high furosemide dose and light restriction of sodium intake compared with a high-dose infusion of furosemide alone on pulmonary capillary wedge pressure (PCWP), as determined by Doppler echocardiography and tissue Doppler imaging in patients suffering from decompensated heart failure.

METHODS AND RESULTS

Consecutive patients in New York Heart Association functional class IV, unresponsive to oral high doses of furosemide up to 250-500 mg/d and/or combinations of diuretics, with ejection fraction <40%, serum creatinine <2 mg/dL, blood urea nitrogen ≤60 mg/dL, reduced urinary volume (<500 mL/24 h), and low natriuresis (<60 mEq/24 h) were randomized into 2 groups (double blind). The first group received a furosemide infusion (250 mg) plus HSS (150 mL 3.0% Na) bid and light Na restriction (120 mmol), and the second group received furosemide infusion (250 mg) twice daily, and low Na diet (80 mmol). The fluid intake of both groups was restricted (1 L/d). Body weight, whole-body bioelectrical impedance analysis (BIA), 24-hour urinary volume, and serum and urinary laboratory parameters were measured daily. Estimations of echocardiographic PCWP (Echo-PCWP) were detected on entry, 1 hour after concluding the initial treatment, and 6 days thereafter. A total of 133 patients (47 women and 86 men), aged 65-82 years, met the entry criteria.The HSS group revealed a significant increase in daily diuresis, natriuresis, and serum sodium compared with the furosemide group. Six days after treatment, renal function was significantly improved in the HSS group. Both groups showed a significant reduction in Echo-PCWP, but the HHS group revealed a faster reduction and significant lower values at 6 days compared with the group taking furosemide alone. We observed a positive correlation between values of Echo-PCWP and BNP and an inverse correlation between BIA parameters and Echo-PCWP.

CONCLUSIONS

Our data show that the combination of high diuretic dose and HSS infusion plus light restriction in dietary sodium intake determine a more rapid and significant hemodynamic stabilization through the improvement of echo-PCWP, BNP levels, and BIA parameters than the group treated without HSS.

Diuretics in clinical practice. Part I: mechanisms of action, pharmacological effects and clinical indications of diuretic compounds

IMPORTANCE OF THE FIELD

Diuretics are among the most important drugs of our therapeutic armamentarium and have been broadly used for > 50 years, providing important help towards the treatment of several diseases. Although all diuretics act primarily by impairing sodium reabsorption in the renal tubules, they differ in their mechanism and site of action and, therefore, in their specific pharmacological properties and clinical indications. Loop diuretics are mainly used for oedematous disorders (i.e., cardiac failure, nephrotic syndrome) and for blood pressure and volume control in renal disease; thiazides and related agents are among the most prescribed drugs for hypertension treatment; aldosterone-blockers are traditionally used for primary or secondary aldosteronism; and other diuretic classes have more specific indications.

AREAS COVERED IN THIS REVIEW

This article discusses the mechanisms of action, pharmacological effects and clinical indications of the various diuretic classes used in everyday clinical practice, with emphasis on recent knowledge suggesting beneficial effects of certain diuretics on clinical conditions distinct from the traditional indications of these drugs (i.e., heart protection for aldosterone blockers).

WHAT THE READER WILL GAIN

Reader will gain insights into the effective use of diuretic agents for various medical conditions, representing their established or emerging therapeutic indications.

TAKE HOME MESSAGE

Knowledge of the pharmacologic properties and mechanisms of action of diuretic agents is a prerequisite for the successful choice and effective clinical use of these compounds.

The effects of diuretics on intracellular Ca2+ dynamics of arteriole smooth muscles as revealed by laser confocal microscopy

The regulation of cytosolic Ca²⁺ homeostasis is essential for cells, including vascular smooth muscle cells. Arterial tone, which underlies the maintenance of peripheral resistance in the circulation, is a major contributor to the control of blood pressure. Diuretics may regulate intracellular Ca²⁺ concentration ([Ca²⁺]_i) and have an effect on vascular tone. In order to investigate the influence of diuretics on peripheral resistance in circulation, we investigated the alteration of [Ca²⁺]_i in testicular arterioles with respect to several categories of diuretics using real-time confocal laser scanning microscopy. In this study, hydrochlorothiazide (100 µM) and furosemide (100 µM) had no effect on the [Ca²⁺]_i dynamics. However, when spironolactone (300 µM) was applied, the [Ca²⁺]_i of smooth muscles increased. The response was considerably inhibited under either extracellular Ca²⁺-free conditions, the presence of Gd³⁺, or with a treatment of diltiazem. After the thapsigargin-induced depletion of internal Ca²⁺ store, the spironolactone-induced [Ca²⁺]_i dynamics was slightly inhibited. Therefore, the spironolactone-induced dynamics of [Ca²⁺]_i can be caused by either a Ca²⁺ influx from extracellular fluid or Ca²⁺ mobilization from internal Ca²⁺ store, with the former being dominant. As tetraethylammonium, an inhibitor of the K⁺ channel, slightly inhibited the spironolactone-induced [Ca²⁺]_i dynamics, the K⁺ channel might play a minor role in those dynamics. Tetrodotoxin, a neurotoxic Na⁺ channel blocker, had no effect, therefore the spironolactone-induced dynamics is a direct effect to smooth muscles, rather than an indirect effect via vessel nerves.

Performing repeated noninvasive bedside measures of volume response to intravenous furosemide in acute pulmonary edema: a feasibility assessment

Optimizing responses to intravenous furosemide (ivF) in acute pulmonary edema is limited by current insensitive noninvasive means of volume assessment. We conducted a pilot study to assess the feasibility of performing repeated measures of echocardiographic and bioimpedance analysis (BIA) parameters and test their response as noninvasive markers of volume response to ivF. We also aimed to identify the most potentially sensitive markers of this response. Patients receiving ivF for a clinical diagnosis of acute cardiogenic pulmonary edema were studied. Echocardiographic and BIA parameters were measured at 0, 0.5, 1, 2, and 3 h after ivF. Intraobserver variability for each parameter was determined. Thirty-one patients were enrolled who were receiving 40-100 mg of ivF. Transmitral (MV) early peak velocity following Valsalva maneuver and transtricuspid (TV) early peak velocity reduced significantly (P= 0.012 and 0.010, respectively), whereas MV deceleration time increased significantly (P= 0.006) in response to ivF. Short-axis inferior vena cava diameter (SIVC) in expiration and inspiration and SIVC corrected for body surface area in expiration and inspiration reduced significantly following ivF (P= 0.039, 0.020, 0.032, and 0.016, respectively). BIA estimates of extracellular water decreased significantly (P= 0.001), whereas impedance (Z) at currents of 5, 50, 100, and 200 kHz increased following ivF; the changes were significant with all but the last parameter (P < 0.0001, 0.006, 0.010, and 0.051, respectively). Maximal change from baseline for each parameter was greater than its respective intraobserver variability. Performing repeated measures of echocardiographic and BIA parameters is feasible in this unstable group of patients. The above panel of parameters could potentially be used to track volume response to ivF and, thus, to optimize treatment in acute pulmonary edema.

Medium term effects of different dosage of diuretic, sodium, and fluid administration on neurohormonal and clinical outcome in patients with recently compensated heart failure

Studies have shown that patients with compensated heart failure (HF) receiving high diuretic doses associated with normal sodium diet and fluid intake restrictions demonstrated significant reductions in readmissions and mortality compared with those who received low-sodium diets, and over a 6-month observation period, a reduction in neurohormonal activation was also observed. The aim of this study was to evaluate the effects of different sodium diets associated with different diuretic doses and different levels of fluid intake on hospital readmissions and neurohormonal changes after 6-month follow-up in patients with compensated HF. Four hundred ten consecutive patients with compensated HF (New York Heart Association class II to IV) aged 53 to 86 years, with ejection fractions <35% and serum creatinine <2 mg/dl, were randomized into 8 groups: group A (n = 52): 1,000 ml/day of fluid intake, 120 mmol/day, and 250 mg furosemide twice daily; group B (n = 51): 1,000 ml/day of fluid intake, 120 mmol/day, and 125 mg furosemide twice daily; group C (n = 51): 1,000 ml/day fluid intake, 80 mmol/day, and 250 mg furosemide twice daily; group D (n = 51): 1,000 ml/day fluid intake, 80 mmol/day, and 125 mg furosemide twice daily; group E (n = 52): 2,000 ml/day fluid intake, 120 mmol/day, and 250 mg furosemide twice daily; group F (n = 50): 2,000 ml/day fluid intake, 120 mmol/day, and 125 mg furosemide twice daily; group G (n = 52): 2,000 ml/day fluid intake, 80 mmol/day, and 250 mg furosemide twice daily; and group H (n = 51): 2,000 ml/day fluid intake, 80 mmol/day, and 125 mg furosemide twice daily. All patients received the treatments >or=30 days after discharge and for 180 days afterward. Signs of HF, body weight, blood pressure, heart rate, laboratory parameters, electrocardiograms, echocardiograms, brain natriuretic peptide, aldosterone, and plasma renin activity were examined at baseline and 180 days later. Group A showed the best results, with a significant reduction (p <0.001) in readmissions, brain natriuretic peptide, aldosterone, and plasma renin activity compared with the other groups during follow-up (p <0.001). In conclusion, these data suggest that the combination of a normal-sodium diet with high diuretic doses and fluid intake restriction, compared with different combinations of sodium diets with more modest fluid intake restrictions and conventional diuretic doses, leads to reductions in readmissions, neurohormonal activation, and renal dysfunction.

Normal-sodium diet compared with low-sodium diet in compensated congestive heart failure: is sodium an old enemy or a new friend?

The aim of the present study was to evaluate the effects of a normal-sodium (120 mmol sodium) diet compared with a low-sodium diet (80 mmol sodium) on readmissions for CHF (congestive heart failure) during 180 days of follow-up in compensated patients with CHF. A total of 232 compensated CHF patients (88 female and 144 male; New York Heart Association class II–IV; 55–83 years of age, ejection fraction <35% and serum creatinine <2 mg/dl) were randomized into two groups: group 1 contained 118 patients (45 females and 73 males) receiving a normal-sodium diet plus oral furosemide [250–500 mg, b.i.d. (twice a day)]; and group 2 contained 114 patients (43 females and 71 males) receiving a low-sodium diet plus oral furosemide (250–500 mg, b.i.d.). The treatment was given at 30 days after discharge and for 180 days, in association with a fluid intake of 1000 ml per day. Signs of CHF, body weight, blood pressure, heart rate, laboratory parameters, ECG, echocardiogram, levels of BNP (brain natriuretic peptide) and aldosterone levels, and PRA (plasma renin activity) were examined at baseline (30 days after discharge) and after 180 days. The normal-sodium group had a significant reduction (P<0.05) in readmissions. BNP values were lower in the normal-sodium group compared with the low sodium group (685±255 compared with 425±125 pg/ml respectively; P<0.0001). Significant (P<0.0001) increases in aldosterone and PRA were observed in the low-sodium group during follow-up, whereas the normal-sodium group had a small significant reduction (P=0.039) in aldosterone levels and no significant difference in PRA. After 180 days of follow-up, aldosterone levels and PRA were significantly (P<0.0001) higher in the low-sodium group. The normal-sodium group had a lower incidence of rehospitalization during follow-up and a significant decrease in plasma BNP and aldosterone levels, and PRA. The results of the present study show that a normal-sodium diet improves outcome, and sodium depletion has detrimental renal and neurohormonal effects with worse clinical outcome in compensated CHF patients. Further studies are required to determine if this is due to a high dose of diuretic or the low-sodium diet.

Function and regulation of epithelial sodium transporters in the kidney of a salt-sensitive hypertensive rat model

OBJECTIVE

To determine the function and regulation of thiazide-sensitive NaCl co-transporters (NCC), NaK2Cl co-transporters (NKCC2), and epithelial sodium channels (ENaC) in the kidneys of a salt-sensitive hypertensive model.

DESIGN AND METHODS

Neonatal Wistar rats were treated with capsaicin or vehicle. Seven-week-old male rats were treated for 2 weeks with: vehicle plus a normal (Con-NS) or high (Con-HS) sodium diet, and capsaicin pretreatment plus a normal (Cap-NS) or high (Cap-HS) sodium diet. Mean arterial pressure (MAP), renal excretory function, and protein expression determined by western blot were performed.

RESULTS

MAP was increased in Cap-HS compared with other groups. Trichlormethiazide increased urine sodium excretion (UNaV) and urine flow rate (UFR) and decreased MAP in Cap-HS rats only. Furosemide increased UNaV and UFR in Cap-NS, Con-HS and Cap-HS, and decreased MAP in Cap-HS rats only. Amiloride had no effect on UNaV, UFR and MAP in any group. Renal NCC contents were increased in Cap-HS compared with Con-NS, Con-HS and Cap-NS rats, and NKCC2 expression was increased in Cap-NS, Con-HS and Cap-HS compared with Con-NS rats. No change was found in ENaC alpha subunit expression. The capsaicin-induced release of calcitonin gene-related peptide from renal tissues was decreased in Cap-HS and Cap-NS compared with Con-HS and Con-NS rats.

CONCLUSION

NCC and possibly NKCC2, but not ENaC, were functionally upregulated in the kidneys of rats subjected to sensory nerve degeneration plus high salt intake, suggesting that sensory neurotransmitters may regulate the expression of the former but not the latter, which may underlie the development of salt-sensitive hypertension in this model.

Novel strategies: challenge loop diuretics and sodium management in heart failure--Part I

This is the first of a 2-part series. This article reviews the relationships among diuretics, neurohormonal activation, renal function, fluid and Na management, the cardiorenal syndrome, and heart failure. Part II will describe novel therapies based on these relationships, focusing particularly on vasopressin antagonists and treatment using hypertonic saline solution with high-dose loop diuretics. Heart failure (HF) is a complex hemodynamic disorder characterized by chronic and progressive pump failure and fluid accumulation. Diuretics are a vital component of symptomatic management, and enhancing diuretic response in the setting of diuretic resistance is therefore pivotal. In HF patients treated with diuretics, compensatory pathophysiologic mechanisms to maintain vascular resistance, such as nonosmotic stimulation of vasopressin secretion and activation of the renin-angiotensin-aldosterone system and sympathetic nervous system, promote renal Na and water reabsorption. Thus, there remains a need to develop novel therapies for HF patients who are refractory to conventional medical treatment. The conflicting results of diuretic treatments in HF and the importance of Na management in the context of the cardiorenal syndrome and neurohormonal activation have suggested novel and counterintuitive strategies, focusing primarily on the use of vasopressin antagonists and hypertonic saline solution with high doses of loop diuretics and neurohormonal interference. The authors review the current evidence for these therapies and suggest hypothetical bases for their efficacy.

Thiazide‐Type Diuretics: Ongoing Considerations on Mechanism of Action

Thiazide-type diuretics have enjoyed a considerable success in the management of hypertension. These drugs have assumed a standard-of-care position in the minds of many health care providers; however, a number of questions remain unresolved in relation to their use. Such questions include issues of mechanism of action, comparability to loop-diuretics in their actions, class-effect, and the basis for their additivity with non-diuretic antihypertensive medication classes. Understanding these issues is important to the effective use of these compounds.

Vasodilatory action of loop diuretics: a plethysmography study of endothelial function in forearm arteries and dorsal hand veins in hypertensive patients and controls

INTRODUCTION

Intravenous administration of loop diuretics induces venodilation before the diuretic response. We investigated whether furosemide and torasemide exert a dilatory effect on arteries and veins mediated by endothelial release of nitric oxide.

METHODS

We performed intermittent venous occlusion plethysmography to study forearm blood flow and dorsal hand-vein distension in response to furosemide and torasemide infusion in hypertensive patients and healthy controls.

RESULTS

Furosemide increased venodilation from 0.56 +/- 0.09 to 0.88 +/- 0.06 (P=0.000) in control subjects and from 0.49 +/- 0.10 to 0.75 +/- 0.12 (P=0.000) in hypertensive patients. Torasemide increased venodilation from 0.46 +/- 0.06 to 0.70 +/- 0.11 (P=0.007) in control subjects and from 0.48 +/- 0.09 to 0.67 +/- 0.12 (P = 0.03) in hypertensive patients. Co-infusion of the Nitric Oxide Synthase Inhibitor (L-NMMA)-blocked this venodilation, and the action was reversed with L-arginine. There were no significant changes in the arterial bed.

CONCLUSIONS

Furosemide and torasemide induce a similar dose-response curve venodilation, but they have no effect on the arterial bed. Hypertensive patients show a smaller venous endothelium-dependent response than healthy controls. The venodilation induced by both diuretics requires release of nitric oxide.

Practical applications of intravenous diuretic therapy in decompensated heart failure

Intravenous (IV) loop diuretics play an important role in the treatment of decompensated heart failure (DHF). They inhibit the Na(+)-K(+)-2Cl(-) reabsorptive pump in the thick ascending limb of the loop of Henle, and the resultant natriuresis and diuresis decreases volume load, improves hemodynamics, and reduces DHF symptoms. However, loop diuretics have a short half-life and their efficacy may be limited by postdiuretic sodium rebound during the period between doses in which the tubular diuretic concentration is subtherapeutic. Moreover, they can produce electrolyte abnormalities, neurohormonal activation, intravascular volume depletion, and renal dysfunction. Several studies have reported an association between diuretic therapy and increased morbidity and mortality. In addition, many patients, especially those with more advanced forms of heart failure (HF), are resistant to standard doses of loop diuretics. These high-risk, resistant patients may benefit from pharmacologic and/or nonpharmacologic interventions to improve hemodynamic performance, treatment of renovascular disease, discontinuation of aspirin and other sodium-retaining drugs, manipulation of the route of delivery or combination of diuretic classes, or hemofiltration. Despite >50 years of use, many questions regarding the use of intravenous diuretic agents in patients with DHF are still unanswered, and there remains a compelling need for well-designed randomized, controlled clinical trials to establish appropriate treatment regimens that maximize therapeutic benefit while minimizing morbidity and mortality.

Na+ -K+ -2Cl- cotransporter is implicated in gender differences in the response of the rat aorta to phenylephrine

Inhibition of the Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) with bumetanide reduced contractile responses to phenylephrine (PE) in male rat aortas (129+/-4% of 60 mM KCl-induced contraction control vs 108+/-7% bumetanide; PE 10(-5) M; P<0.01) but did not change equivalent responses in female rat aortas. Removal of the endothelium blunted the effect of NKCC1 inhibition on the response to PE (10(-5) M) in males, whereas in denuded aorta from female rats, bumetanide reduced this response (162+/-5% control vs 146+/-3% bumetanide; P<0.05). NKCC1 basal activity did not show gender differences in intact aortic rings, but in the presence of PE, bumetanide-sensitive (86)Rb(+)/K(+) uptake increased more in male than female aortas (179+/-8 in males vs 158+/-5 nmol (86)Rb(+)/K(+) min(-1) (g aorta)(-1) in females; P<0.05). PE did not stimulate NKCC1 activity in denuded aorta from male rats. However, in female rats, PE increased NKCC1 activity similarly in both denuded (169+/-11 nmol (86)Rb(+)/K(+) min(-1) (g aorta)(-1)) and intact aortas. Ovariectomy increased the bumetanide-sensitive (86)Rb(+)/K(+) uptake increase elicited by PE (223+/-17 nmol (86)Rb(+)/K(+) min(-1) (g aorta)(-1)) and hormone replacement with 17beta-estradiol prevented this effect (159+/-29 nmol (86)Rb(+)/K(+) min(-1) (g aorta)(-1)). Na(+),K(+)-ATPase basal activity, measured as ouabain-sensitive (86)Rb(+)/K(+) uptake, was similar in male and female rats, but the effect of PE was significantly less in intact male aortas (232+/-16 in males vs 296+/-25 nmol (86)Rb(+)/K(+) min(-1) (g aorta)(-1) in females; P<0.05). Our results suggest that PE induced activation of NKCC1 and Na(+),K(+)-ATPase in the rat aorta in a gender-dependent way.

Ultrafiltration in decompensated heart failure

Fluid congestion is the hallmark of decompensated heart failure. As heart failure progresses, reduced response to diuretics is common. In these patients, ultrafiltration has been found to alleviate excess volume and improve diuretic sensitivity. Compared with diuretics, ultrafiltration provides a more predictable and safer way to achieve euvolemia with minimal electrolyte abnormalities and neurohormonal activation. The emerging familiarity and ease of use of ultrafiltration suggests that in the future this will be an important therapy for the treatment of acute and chronic volume overload associated with decompensated heart failure.

Modern Management of Cardiogenic Pulmonary Edema

Cardiogenic pulmonary edema (CPE) is a life-threatening condition that is frequently encountered in standard emergency medicine practice. Traditionally, diagnosis was based on physical assessment and chest radiography and treatment focused on the use of morphine sulfate and diuretics. Numerous advances in diagnosis and treatment have been made, however. Serum testing for B-type natriuretic peptide (BNP) has improved the accuracy of diagnoses in these patients. Treatment should focus on fluid redistribution with aggressive preload and afterload reduction rather than simply on diuresis. Some specific medications and noninvasive positive pressure ventilation have been shown to be safe and rapidly effective in improving patients' symptoms and improve outcomes.