Clinical Need

Heart Failure Patients and Intravascular Volume Status

Heart failure is a serious and common disease. About 5.7 million people in the U.S. experience heart failure, and that number is growing (NIH). “Heart failure” doesn’t mean that your heart has stopped working. It is related to the heart’s inability to pump enough blood to meet a body’s needs. As the NIH notes, “In some cases, the heart can’t fill with enough blood. In other cases, the heart can’t pump blood to the rest of the body with enough force. Some people have both problems.”

Heart failure accounts for more than 1 million hospitalizations each year, of which 90% are due to intravascular volume overload.

Intravascular Volume Status

Blood volume is the amount of blood a person has in their body, which is approximately five liters for an adult. The intravascular volume, or plasma volume (PV), is the amount of plasma within the blood. The plasma volume and blood volume are informative to the health care professional regarding the overall fluid status of the patient. The fluid status of the blood is regulated by the kidneys.

Kidney Function

The body’s Glomerular Filtration Rate (GFR) is the primary indicator of kidney health, injury, disease progression and recovery. Injured kidneys are often unable to regulate fluid in the blood, leading to an imbalance in a patient’s fluid status.

In volume overload situations, patients have too much fluid in their system, which can lead to issues efficiently moving blood through the body. You can think of it like water pressure in a home. If there is too much water, it’s hard on the pumps because they’re trying to move too much. Volume overload is hard on the heart, and the best way to treat patients who are over-volume is to reduce the amount of volume.

To best understand a patient’s volume status, it should be quantitatively measured. Knowing volume status is key in critical care, and The American College of Cardiology and American Heart Association recommend assessing volume status in all heart failure patients. Even small 10% increases in volume are directly linked to worse outcomes and longer hospital stays.

Unfortunately, there is no standard of care for measuring volume status.

Current Monitoring, Assessment and Treatment Falls Short

Today, monitoring a patient's volume status typically includes general measurements such as observations of changes in vital signs, physical exam, and monitoring fluid intake and output. Unfortunately, none of these provide the health care professional a quantitative measure of PV; therefore, the health care professional must use all available data to estimate the patient’s true PV.

The cornerstone of treatment for volume overloaded heart failure patients is diuretics. However, because direct measures of PV are lacking, this makes the actual clinical assessment of volume overload challenging and often inaccurate. Intravascular volume can be low even when the patient appears volume overloaded due to fluid accumulation in the interstitial space. While diuretics coupled with sodium and fluid restriction are the first line of treatment, the appropriate extent of diuresis can be difficult to gauge. Approximately 50% of heart failure patients are often discharged without measured weight loss, that is, without knowing if the therapies to reduce their volume overload was successful.

An ongoing challenge in managing patients with Heart Failure is accurately assessing fluid status. In acute heart failure, it is extremely important to be able to appropriately decongest patients. The inaccuracy of current clinical assessments commonly result in discharging patients who are still congested, and as such, the rehospitalization rates are still high despite good available therapies. Assessment of fluid status is confounded by common comorbidities such as obesity, diabetes and renal dysfunction.

The FAST BioMedical solution has the potential to address this clinical challenge in real time when the practice results need this information. Having volume and renal measurements at the bedside makes the FAST BioMedical technology promising and unique.

- Dr. Steven Zelenkofske, Chief Medical Officer, SwanBio Therapeutics

mGFR vs. eGFR
Glomerular Filtration Rate (GFR) is the primary indicator of kidney health, injury, disease progression and recovery. It is also a way to ensure the kidneys are properly regulating fluid in the blood, thus allowing physicians to better monitor volume status. Today, the best measurement for GFR is an estimate (eGFR) using Serum Creatinine (SCr). This is a poor surrogate for true GFR, as it is a trailing indicator by approximately 24-48 hours; therefore, it is inaccurate with respect to the current state of the kidney. Patients can lose approximately 50% of their kidney function by the time the SCr measures above normal, and this slow estimate can impact treatment.

Measured GFR, or mGFR, has the potential to significantly improve treatment. With an accurate reading of mGFR, physicians will be able to better monitor renal function helping to prevent kidney injury. This is highly important when decongesting heart failure patients using diuretics.

FAST BioMedical is working to improve the current system by developing a first-in-class technology to provide rapid, accurate, quantitative, and simultaneous measurements of PV and mGFR in clinically meaningful timeframes.