Blog | Monday, February 6, 2017

Things that bug me includes the improper use of diuretics


Recently our VA ward team had 3 admissions that involved complications of over diuresis for systolic dysfunction. We also see patients who do not have adequate diuresis.

Diuretics greatly help symptoms in patients with systolic dysfunction and volume overload. But diuretics are primarily symptom relief medications.

I often ask students and residents to write this sentence, memorize it, and use it: “The purpose of diuretic therapy in systolic heart failure is render the patient not wet, but not to make the patient dry.”

The idea here is that we should only give enough diuretic therapy to relieve symptoms. Diuretics do not help these patients unless that have volume overload.

Here is the section on diuretics from the 2013 ACC/AHA guideline:

7.3.2.1. Diuretics: Recommendation

Class I

Diuretics are recommended in patients with HFrEF who have evidence of fluid retention, unless contraindicated, to improve symptoms. (Level of Evidence: C)

Diuretics inhibit the reabsorption of sodium or chloride at specific sites in the renal tubules. Bumetanide, furosemide, and torsemide act at the loop of Henle (thus, the term loop diuretics), whereas thiazides, metolazone, and potassium-sparing agents (eg, spironolactone) act in the distal portion of the tubule.427,428 Loop diuretics have emerged as the preferred diuretic agents for use in most patients with HF. Thiazide diuretics may be considered in hypertensive patients with HF and mild fluid retention because they confer more persistent antihypertensive effects.

Controlled trials have demonstrated the ability of diuretic drugs to increase urinary sodium excretion and decrease physical signs of fluid retention in patients with HF.429,430 In intermediate-term studies, diuretics have been shown to improve symptoms and exercise tolerance in patients with HF431–433; however, diuretic effects on morbidity and mortality are not known. Diuretics are the only drugs used for the treatment of HF that can adequately control the fluid retention of HF. Appropriate use of diuretics is a key element in the success of other drugs used for the treatment of HF. The use of inappropriately low doses of diuretics will result in fluid retention. Conversely, the use of inappropriately high doses of diuretics will lead to volume contraction, which can increase the risk of hypotension and renal insufficiency.

7.3.2.1.1. Diuretics: Selection of Patients.

Diuretics should be prescribed to all patients who have evidence of, and to most patients with a prior history of, fluid retention. Diuretics should generally be combined with an ACE inhibitor, beta blocker, and aldosterone antagonist. Few patients with HF will be able to maintain target weight without the use of diuretics.

7.3.2.1.2. Diuretics: Initiation and Maintenance.

The most commonly used loop diuretic for the treatment of HF is furosemide, but some patients respond more favorably to other agents in this category (eg, bumetanide, torsemide) because of their increased oral bioavailability.434,435 Table 14 lists oral diuretics recommended for use in the treatment of chronic HF. In outpatients with HF, diuretic therapy is commonly initiated with low doses, and the dose is increased until urine output increases and weight decreases, generally by 0.5 to 1.0 kg daily. Further increases in the dose or frequency (ie, twice-daily dosing) of diuretic administration may be required to maintain an active diuresis and sustain weight loss. The ultimate goal of diuretic treatment is to eliminate clinical evidence of fluid retention. Diuretics are generally combined with moderate dietary sodium restriction. Once fluid retention has resolved, treatment with the diuretic should be maintained in some patients to prevent the recurrence of volume overload. Patients are commonly prescribed a fixed dose of diuretic, but the dose of these drugs frequently may need adjustment. In many cases, this adjustment can be accomplished by having patients record their weight each day and adjusting the diuretic dosage if weight increases or decreases beyond a specified range. Patients may become unresponsive to high doses of diuretic drugs if they consume large amounts of dietary sodium, are taking agents that can block the effects of diuretics (eg, nonsteroidal anti-inflammatory drugs [NSAIDs], including cyclooxygenase-2 inhibitors)436–438 or have a significant impairment of renal function or perfusion.434 Diuretic resistance can generally be overcome by the intravenous administration of diuretics (including the use of continuous infusions)439 or combination of different diuretic classes (eg, metolazone with a loop diuretic).440–443

Oral Diuretics Recommended for Use in the Treatment of Chronic HF

7.3.2.1.3. Diuretics: Risks of Treatment.

The principal adverse effects of diuretics include electrolyte and fluid depletion, as well as hypotension and azotemia. Diuretics can cause the depletion of potassium and magnesium, which can predispose patients to serious cardiac arrhythmias.444 The risk of electrolyte depletion is markedly enhanced when 2 diuretics are used in combination.

Here is what bugs me the most. The proper use of diuretics for these patients requires an understanding of the pharmacokinetics, renal tubular function in addition to the pathophysiology of systolic dysfunction. These concepts are not that complex, but we find few students or residents who really understand the entire package necessary to use diuretics for the patient's greatest benefit.

And yet “heart failure” is the single most expensive Medicare diagnosis. We should all become experts at managing volume disturbances in these patients.

Several studies have suggested that using more diuretics increase mortality (given the same cardiac function). Thus, we should strive to use the lowest doses and less frequency feasible for the patient.

This bugs me because too often patients suffer from our ignorance. Internists and family physicians must all become experts in the management of these patients, and managing the diuretic therapy is a major component.

Rant over; thanks for reading. Please feel free to make suggestions on things that bug me. I have a modest list, and will be posting some of these over the next month, but would love your personal things that bug you!

db is the nickname for Robert M. Centor, MD, FACP. db stands both for Dr. Bob and da boss. He is an academic general internist at the University of Alabama School of Medicine, and is the Regional Associate Dean for the Huntsville Regional Medical Campus of UASOM. He still makes inpatient rounds over 100 days each year. This post originally appeared at his blog, db's Medical Rants.