Mechanisms and management of diuretic resistance in congestive heart failure

The added-up albumin enhances the diuretic effect of furosemide in patients with hypoalbuminemic chronic kidney disease: a randomized controlled study

Background

Chronic kidney disease (CKD) with edema is a common clinical problem resulting from defects in water and solute excretion. Furosemide is the drug of choice for treatment. In theory, good perfusion and albumin are required for the furosemide to be secreted at the tubular lumen. Thus, in the situation of low glomerular filtration rate (GFR) and hypoalbuminemia, the efficacy of furosemide alone might be limited. There has been no study to validate the effectiveness of the combination of furosemide and albumin in this condition.

Methods

We conducted a randomized controlled crossover study to compare the efficacy of diuretics between furosemide alone and the combination of furosemide plus albumin in stable hypoalbuminemic CKD patients by measuring urine output and sodium. The baseline urine output/sodium at 6 and 24 hours were recorded. The increment of urine output/sodium after treatment at 6 and 24 hours were calculated by using post-treatment minus baseline urine output/sodium at the corresponding period.

Results

Twenty-four CKD patients (GFR = 31.0 ± 13.8 mL/min) with hypoalbuminemia (2.98 ± 0.30 g/dL) were enrolled. At 6 hours, there were significant differences in the increment of urine volume (0.47 ± 0.40 vs 0.67 ± 0.31 L, P < 0.02) and urine sodium (37.5 ± 29.3 vs 55.0 ± 26.7 mEq, P < 0.01) between treatment with furosemide alone and with furosemide plus albumin. However, at 24 hours, there were no significant differences in the increment of urine volume (0.49 ± 0.47 vs 0.59 ± 0.50 L, P = 0.46) and urine sodium (65.3 ± 47.5 vs 76.1 ± 50.1 mEq, P = 0.32) between the two groups.

Conclusion

The combination of furosemide and albumin has a superior short-term efficacy over furosemide alone in enhancing water and sodium diuresis in hypoalbuminemic CKD patients.

Trial registration

The Australian New Zealand Clinical Trials Registration (ANZCTR12611000480987)

Diuretics and ultrafiltration in acute decompensated heart failure

Congestion and volume overload are the hallmarks of acute decompensated heart failure (ADHF), and loop diuretics have historically been the cornerstone of treatment. The demonstrated efficacy of loop diuretics in managing congestion is balanced by the recognized limitations of diuretic resistance, neurohormonal activation, and worsening renal function. However, the recently published DOSE (Diuretic Optimization Strategies Evaluation) trial suggests that previous concerns about the safety of high-dose diuretics may not be valid. There has been a growing interest in alternative strategies to manage volume retention in ADHF with improved efficacy and safety profiles. Peripheral venovenous ultrafiltration (UF) represents a potentially promising approach to volume management in ADHF. Small studies suggest that UF may allow for more effective fluid removal compared with diuretics, with improved quality of life and reduced rehospitalization rates. However, further investigation is needed to completely define the role of UF in patients with ADHF. This review summarizes available data on the use of both diuretics and UF in ADHF patients and identifies challenges and unresolved questions for each approach.

[Acute heart failure]

Acute decompensated heart failure (ADHF) is a major public health problem throughout the world and its importance is continuing to grow. More than 50% of ADHF patients have coronary artery disease, which is generally associated with a history of hypertension. Recent data suggest that half of the patients presenting with acute heart failure have preserved left ventricular systolic function. The diagnosis of ADHF may be difficult at times, and the clinical assessment and patient profiling is essential for appropriate therapy. Immediate therapeutic goals are not only to improve symptoms, restore oxygenation and stabilize hemodynamic conditions, but also to improve short- and long-term survival. In addition to general supportive measures such as oxygen supplementation, noninvasive ventilation, analgesia, diuretics, vasodilators together with inotropic agents and/or vasopressors remain the cornerstone of therapy in patients with ADHF.

Clinical Experience With Low-Dose Continuous Infusion of Furosemide in Acute Heart Failure

Introduction:

Clinical data are scarce for furosemide administered as a low-dose (<160 mg/24 hours) continuous intravenous infusion in acute heart failure (HF). Our purpose was to evaluate the efficacy and safety of low-dose continuous infusion of furosemide on diuretic response, renal function, and patient outcomes.

Methods:

A retrospective study of patients with acute HF who received furosemide administered as a continuous infusion after initial therapy with intermittent boluses (usually 40-80 mg every 12 hours). End points included mean hourly urine output, incidence of acute renal injury, and outcome disparities of patients who developed acute renal injury. Comparison of patients with preserved and reduced left ventricular ejection fraction (LVEF) was also performed.

Results:

The study included 150 patients (age 57 ± 13 years, male gender 61%, admission weight 87 ± 32 kg, LVEF 37 ± 15%, 28% preserved LVEF). Mean initial and maximum furosemide doses were 5.1 ± 1.1 mg/h and 6.2 ± 2.2 mg/h, respectively. Mean duration of therapy was 51.4 ± 67.5 hours. Continuous infusion of furosemide was associated with a significant increase in mean hourly urine output compared to baseline (150 ± 77 mL/h vs 116 ± 69 mL/h, P < .001). Acute renal injury developed in 19% of patients, with 70% of those occurring within the first 48 hours of therapy. Mean serum creatinine (baseline 1.55 ± 1.50 mg/dL vs at discharge 1.64 ± 1.61 mg/dL, P = .20) and estimated glomerular filtration rate (baseline 67 ± 39 mL/min vs at discharge 67 ± 43 mL/min, P = .89) did not significantly change over the course of the hospitalization. Development of acute renal injury was associated with poorer outcomes, higher furosemide dose, and longer duration of furosemide therapy. Diuretic response and safety were not different between patients with preserved or reduced LVEF.

Conclusions:

In patients with acute HF, furosemide administered as a low-dose continuous infusion was effective in achieving diuresis and was not associated with a detectable effect on renal function. This diuretic approach appeared to be similarly effective and safe in patients with preserved LVEF.

Impact of diuretic dosing on mortality in acute heart failure using a propensity-matched analysis

AIMS

Loop diuretics are recommended to treat congestion in heart failure (HF), despite limited quality evidence. High-dose (HD) loop diuretics seem to worsen outcomes in chronic HF, though; data for acute HF are scarce, with equivocal results.

METHODS AND RESULTS

The ALARM-HF study recorded in-hospital HF therapy in 4953 patients from nine countries. A post-hoc analysis was performed to determine if there was an interaction between intravenous (iv) bolus diuretic dosing and outcomes. Patients were classified as receiving high- or low-dose iv furosemide if their total initial 24 h dose was above (HD) or below [low dose (LD)] 1 mg/kg. Propensity scoring, matching an extensive list of variables, was performed. High-dose and LD patients were matched by propensity scores and outcomes determined. We identified 2460 LD and 848 HD patients, with overall in-hospital mortality of 9 and 13% (P= 0.002), respectively. After propensity matching, there were 506 patients in each subgroup, with the matched LD and HD cohorts having similar mortality (13 vs. 15%; P= 0.4). We further investigated in which subgroups of patients HD diuretics influenced mortality. Before matching, HD diuretics were associated with a greater risk of in-hospital death in some subgroups, including patients aged >80 years, those with an acute coronary syndrome, or with a left ventricular ejection fraction <40%. However, after propensity score matching, no association was found between diuretic dosing and death in any of the studied subgroups.

CONCLUSIONS

In the initial management of acute HF, HD iv diuretics, per se, do not influence short-term mortality.

Anti-edematous effects of tolvaptan in experimental rodent models

PURPOSE

The aim of this study was to evaluate the therapeutic efficacy of tolvaptan, a vasopressin V(2) receptor antagonist, on edema in two rat models: 1) histamine-induced vascular hyperpermeability of the dorsal skin and 2) carrageenan-induced paw edema.

METHODS

In the skin vascular hyperpermeability model, 3 h after oral administration of tolvaptan or the natriuretic agent furosemide, rats were intravenously injected with Evans Blue (EB), followed by intradermal injection of 10 μg of histamine into the dorsal skin. One hour later, blood was collected to measure serum parameters. EB leakage area into the dorsal skin was also measured. Urine was collected for 4 h to determine urine parameters. In the paw edema model, edema was induced by injecting 1% w/v carrageenan into the right hind paw. Paw volume was measured hourly for 5 h. Tolvaptan or furosemide was orally administered 1 h before carrageenan injection.

RESULTS

A single oral dose of tolvaptan (1-10 mg/kg) elicited marked and dose-dependent aquaresis, and improvements in edema. Similar effects were observed with furosemide (30 mg/kg). Tolvaptan tended to elevate the serum sodium level while furosemide caused a significant decrease.

CONCLUSION

Tolvaptan had anti-edematous effects in two different rat models. By increasing free water excretion, tolvaptan may be more advantageous for certain patients than loop diuretics because it does not cause electrolyte loss, and may prevent electrolyte abnormities, such as hyponatremia. These results suggest that tolvaptan has potential clinical benefits for the treatment of edema.

The challenge of treating congestion in advanced heart failure

Volume overload is a common manifestation of heart failure decompensation. Interaction between impaired renal and heart function constitutes an important pathophysiologic mechanism that leads to congestion. In addition to improving symptoms and volume status, reduction of rehospitalization rates, maintenance of renal function and improvement of survival are all important goals of every therapeutic strategy. Currently, the use of diuretics, vasodilators, inotropes and ultrafiltration, together with investigational agents such as oral vasopressin antagonists and adenosine A1-receptor antagonists, constitute the main therapeutic options for the congested heart failure patient.

The cardiorenal syndrome in heart failure: an evolving paradigm

Heart failure constitutes a significant source of morbidity and mortality in the United States, and its incidence and prevalence continue to grow, increasing its burden on the healthcare system. Renal dysfunction in patients with heart failure is common and has been associated with adverse clinical outcomes. This interaction, termed the cardiorenal syndrome, is a complex phenomenon characterized by a pathophysiologic disequilibrium between the heart and the kidney, in which malfunction of 1 organ consequently promotes the impairment of the other. Multiple neurohumoral mechanisms are involved in this cardiorenal interaction, including the deficiency of and/or resistance to compensatory natriuretic peptides, leading to sodium retention, volume overload and organ remodeling. Management of patients with the cardiorenal syndrome can be challenging and should be individualized. Emerging therapies must address the function of both organs to secure better clinical outcomes. To this end, a multidisciplinary approach is recommended to achieve optimal results.

New therapies in acute decompensated heart failure

PURPOSE OF REVIEW

Hospitalization and mortality rates associated with heart failure are persistently high. This is due partly to aging of the population but mostly to delayed progress in the pharmacological treatment of decompensated heart failure. We will review the current recommendations and most recent advancement in the pharmacological treatment of acute decompensated heart failure while providing a systematic approach to the management of this prevalent condition.

RECENT FINDINGS

Loop diuretics, nitrates and inotropes such as dobutamine and milrinone are the current mainstay of acute heart failure management although their associated morbidity and possible mortality have raised serious concerns. Recent vasoactive agents such as Nesiritide, Tolvaptan and more recently the inotropic agent Levosimedan could offer improved hemodynamics and congestive relief to patients in acute pulmonary edema.

SUMMARY

Despite the promising results of these agents, further clinical trials are required prior to their international approval as first-line therapy. Although we can be optimistic that these vasoactive drugs might have favorable clinical outcomes and improve the intricate management of decompensated heart failure, their associated mortality benefit remains unclear and controversial.

Use of a Novel Ultrafiltration Device as a Treatment Strategy for Diuretic Resistant, Refractory Heart Failure: Initial Clinical Experience in a Single Center

BACKGROUND

The System 100 UF device allows ultrafiltration (UF) via peripheral access and is approved for use in heart failure (HF), although clinical trials defining optimal target population and clinical utility are lacking. We report our initial experience with clinical use of this system in very advanced, diuretic resistant HF patients.

METHODS AND RESULTS

Eleven HF patients (mean age 70 years) underwent 1 to 5 UF treatments each (total 32 UF). The goal was to remove 4 liters of fluid per 8-hour UF. Baseline creatinine averaged 2.2 mg/dL (range .9-3.2) while estimated glomerular filtration rates (GFRs) averaged 38 mL/min (range 20-87). Nine patients (82%) had moderate (GFR 30-59; n = 3) or severe (GFR <30; n = 6) renal dysfunction. Nine patients (82%) had documented right ventricular dysfunction, 6 with severe tricuspid regurgitation. Average daily intravenous furosemide dose prior to UF was 258 mg (range 80-480). Patients had received nesiritide (n = 4), dopamine (n = 4), and zaroxylyn (n = 7) prior to UF. Of the 32 UF treatments, 13 (41%) removed >3500 mL, 11 (34%) removed 2500-3500 mL, and 8 (25%) removed <2500 mL. Only one UF treatment (3%) was aborted due to hypotension. There were no significant complications related to UF. Five patients (45%) experienced an increase in creatinine of >.3 mg/dl. Five patients required dialysis for persistent diuretic resistant volume overload or uremic symptoms. Six-month mortality was 55%.

CONCLUSIONS

Peripheral UF safely but variably removed fluid. In this very high-risk, advanced HF population, 45% of patients developed worsening renal function during UF therapy. Controlled studies are needed to determine the impact of UF on renal function and outcomes in high-risk populations such as this.

Vasopressin antagonists in heart failure

The recrudescence of interest in manipulation of the arginine vasopressin system and especially of V2 vasopressin receptor blockade in heart failure stems from the limited efficacy and possible detrimental effects of loop diuretics. The "braking phenomenon," hypertrophy of the collecting duct cells, and altered pharmacodynamics contribute to loop diuretic resistance in heart failure. Selective (tolvaptan) and nonselective (conivaptan) V2 vasopressin receptor antagonists now known as "vaptans" promote free-water excretion that is labeled aquaresis and correct hyponatremia in patients with severe heart failure. A large mortality study with tolvaptan in heart failure is presently ongoing.

Pharmacological therapy of acute cardiogenic pulmonary oedema in the emergency department

This paper critically reviews the major drug types that are currently used in the management of acute cardiogenic pulmonary oedema. As decompensated heart failure becomes an increasingly common problem in emergency departments in the developed world, optimization of emergency drug therapy for these critically ill patients is essential. The evidence base for 'routine therapy' in the ED is considered. The review also briefly considers emerging pharmacological therapies that may have an impact on future management of cardiogenic pulmonary oedema.