Monitoring Diuretic Therapy in Acute Heart Failure: Biomarkers and Ultrasound

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• Biomarkers in Heart Failure Monitoring
• BNP Levels for Congestion Assessment
• Point-of-Care Ultrasound Evaluation
• Assessing Kidney Function During Diuresis
• Integrating Multiple Assessment Tools
• Full Transcript

Biomarkers in Heart Failure Monitoring

Dr. David Ellison, MD, discusses the ongoing challenge of monitoring patients receiving diuretics for acute heart failure. He emphasizes that defining decongestion remains more of an art than a science. No single definitive test exists for most patients without invasive measures like central venous pressure monitoring.

Dr. David Ellison, MD, explains that while biomarkers supplement the clinical exam, they have limitations. The search for optimal monitoring continues as physicians balance effective diuresis with kidney protection.

BNP Levels for Congestion Assessment

B-type natriuretic peptide (BNP) serves as an important biomarker in heart failure evaluation. Dr. David Ellison, MD, references the 2002 BREATHING NOT PROPERLY trial published in the New England Journal of Medicine. This study demonstrated BNP's effectiveness in differentiating heart failure from pneumonia in emergency department settings.

Dr. David Ellison, MD, notes that declining BNP levels during treatment represent a positive prognostic sign. However, he cautions that BNP isn't a perfect test. Patients with kidney failure often have elevated BNP levels even without fluid congestion. Those with chronic heart failure may maintain chronically high levels, making interpretation challenging.

Point-of-Care Ultrasound Evaluation

Point-of-care ultrasound has become increasingly valuable in assessing heart failure patients. Dr. David Ellison, MD, explains that cardiologists use echocardiograms to evaluate ejection fraction and cardiac filling. This differentiation is crucial since treatment approaches differ significantly between reduced and preserved ejection fraction heart failure.

Dr. David Ellison, MD, highlights the importance of inferior vena cava (IVC) assessment using ultrasound. Evaluating IVC collapsibility helps determine whether a rising creatinine indicates excessive diuresis or requires continued aggressive treatment. This non-invasive method provides real-time data to guide therapeutic decisions.

Assessing Kidney Function During Diuresis

Monitoring kidney function remains critical during aggressive diuretic therapy. Dr. David Ellison, MD, discusses experimental biomarkers that differentiate reduced kidney perfusion from actual kidney damage. Urinary biomarkers like KIM-1 and NGAL can indicate tubular injury when creatinine levels rise.

Dr. David Ellison, MD, emphasizes that careful microscopic urine examination provides valuable information about kidney damage. Nephrologists use this approach to distinguish between reversible perfusion changes and structural injury during heart failure treatment.

Integrating Multiple Assessment Tools

Effective heart failure management requires integrating multiple assessment modalities. Dr. David Ellison, MD, stresses that no magic test exists for determining fluid congestion status. Physicians must combine history, physical examination, ultrasound findings, and biomarker data.

Dr. Anton Titov, MD, facilitates this discussion about comprehensive patient assessment. The conversation with Dr. Ellison reveals that optimal care involves synthesizing information from all available tools. This multidimensional approach provides the best assessment of volume status in complex heart failure patients.

Full Transcript

Dr. Anton Titov, MD: Are there laboratory criteria or certain clinical signs that help to determine if diuretics are used correctly in heart failure, especially in hypertension? Of course, volume overload criteria are important. But is there anything in addition to that?

Dr. David Ellison, MD: Yeah, I think that's a great question. In heart failure, that's been one of the holy grails: how do you monitor patients? I think there are two different types of biomarkers that supplement our clinical exam. But how we define decongestion still is very much an art. There is no one test that we can use definitively, other than if you put a central venous line in and measure the central venous pressure, or a Swan Ganz catheter.

There have been randomized controlled studies showing that for most patients, that doesn't add value. So we still try to assess these things non-invasively. The approaches that can be used include measurement of BNP or B-type natriuretic peptide. And that's not a bad test.

A very long time ago, in 2002, the so-called "Breathing Not Properly" clinical trial in the New England Journal of Medicine showed that the measurement of BNP was a very good test for determining whether patients coming into the emergency department had pneumonia versus heart failure.

I think it's still a very good test. In those situations, there is some data that goes back and forth about whether measuring BNP levels is useful therapeutically in acute decompensated heart failure. But it also is very clear that a decline in BNP levels as one treats heart failure is a very good prognostic sign.

So we measure it all the time, and I look at it. But it's not the definitive test. First of all, because patients with kidney failure have higher BNP levels, even when they are not congested with fluid. And second, people who have chronic heart failure, their BNP levels can be chronically high. And it's much harder to interpret.

So that is a test that's used commonly. I think it is useful. But it's not a silver bullet; it's not a perfect way to assess patients.

In terms of other tests, right now we use a lot of so-called point-of-care ultrasound. And that's a very good test.

Cardiologists will do echocardiograms by which they can assess the ejection fraction and the filling of the heart. And that's really important to know. I would just mention parenthetically that we know a lot about how to treat patients with heart failure with reduced ejection fraction; we know much less about how to treat patients with heart failure with preserved ejection fraction. So that's really an important differential.

But in terms of congestion, we can both look at the neck veins with our eyes, but also with ultrasound. And very commonly now we also use ultrasound to look at the inferior vena cava, the collapsibility of that. And that helps because if you have a patient with a creatinine that's going up, you are giving a lot of diuretics, you want to know whether that's because you really given them too much, or whether you still need to push ahead.

Looking at the inferior vena cava can be a very useful part of your assessment of the patient. So we really look at all of those different things.

And then finally, in terms of the creatinine rise, as I mentioned, at least experimentally, it's very clear that we can assess kidney damage—whether the patient has moved from simply reduced kidney perfusion to actually kidney damage—by using these biomarkers in the urine like KIM-1 or NGAL. And these biomarkers can tell us whether there's been kidney damage.

But frankly, so can just looking at the urine. And one of the things that we do as nephrologists is we do a careful microscopic exam and see whether there's evidence of kidney damage. And that can be very useful in these kinds of situations.

So unfortunately, we still don't have a magic test that tells us the answer about heart congestion, at least for most patients.

We ended up using all of our tools: both our history, our physical exam, devices like an ultrasound device, and also biomarkers like BNP to try and get the best possible assessment of the patient's volume status.