Hypervolemia is defined as excessive fluid in the intravascular compartment. This medical condition has multiple causes and may lead to severe outcomes and mortality.
Fluid overload manifests as pulmonary edema. Hence, the patient experiences dyspnea on exertion, orthopnea, and paroxysmal nocturnal dyspnea. Additionally, another frequent complaint in pulmonary edema secondary to CHF is a cough that produces pink, frothy sputum.
In cases with chronic fluid overload, the patients present with dyspnea and peripheral edema.
Physical exam
Remarkable findings on the lung exam include crackles or rales. The cardiovascular exam is notable for tachycardia, tachypnea, hypertension, jugular venous distension, peripheral edema, and ascites. Moreover, cardiac auscultation may reveal the S3 heart sound.
Further observations include an altered mental status and anxiety.
The clinician should assess the overall clinical picture and patient's history. Other key components of the workup include a physical exam, and laboratory and imaging studies.
Laboratory tests
Measurement of the serum electrolytes will reveal any imbalances such as with sodium and potassium levels. Also important are the serum creatinine and glomerular filtration rate (GFR) levels since these will provide details about the renal function. Furthermore, liver function tests (LFTs) may show hypoalbuminemia.
A useful test, the complete blood count (CBC), will demonstrate manifestations such as anemia, low hematocrit, and infection.
Further studies include the B-type natriuretic peptide (BNP), which can be helpful in diagnosing cardiac failure. Additionally, an arterial blood gas (ABG) is indicated in respiratory failure.
Electrocardiogram
An electrocardiogram (ECG) will identify the heart rate and rhythm, and display existing arrhythmias, hypertrophy, and/or ischemia.
Imaging
A chest X-ray will depict edema and underlying diseases such as pneumonia.
Echocardiography, an important investigation, will provide critical information about the heart performance, the wall measurements, the integrity of the valves, and the presence of heart diseases.
The mainstay treatment for hypervolemia in the hospital setting is the restriction of fluid intake or reduction in IVF. Medical therapy and dietary modifications may be considered as well.
Medications
Diuretic therapy eliminates excess fluid. The various types of diuretics are classified according to which part of the nephron they influence. Additionally, some drug preparations combine a diuretic with an antihypertensive in the same pill. The clinician will choose the appropriate regimen for the patient. Note that certain diuretics may produce hypokalemia and other side effects. Hence, potassium replacement may be required.
Dietary modifications
For outpatients, the fluid intake has to be limited to 2L or less. Also, the sodium consumption should be restricted per the normal daily allowance, which is 2,000mg. Patients must avoid food such as bacon, potato chips, and others products with salt. Alternatives to salt may be used, and these include spices, pepper, and herbs.
Other
Edematous feet should be elevated to prevent fluid pooling in the lower extremities. Sometimes, compression stockings and certain physical activities will help as well.
Profound acute kidney injury (AKI) is complicated by fluid overload, which was initially demonstrated in children who underwent bone marrow transplantation [4]. In fact, 70% of patients of the study warranted dialysis as they did not exhibit renal improvement. Similarly, hypervolemia was prevalent in pediatric populations who needed continuous renal replacement therapy (CRRT) [5] [6] [7] [8] [9] [10].
According to these studies, the severity of overload in itself is indicative of poor outcomes and fatality. The survivors' treatment course was associated with a delay in renal recovery and a prolonged duration of hospitalization and mechanical ventilation [11].
Collectively, these investigations concluded that the presence of hypervolemia is significant in kidney failure. Hence, the excessive fluid volume should be corrected to prevent morbidity and mortality.
There are numerous causes of hypervolemia as described below.
Iatrogenic
Fluid overload may occur when patients receive large amounts of intravenous fluids (IVF), blood transfusions, medications, or contrast dyes. This occurrence is especially observed in the elderly population, postoperative patients, and individuals with heart or kidney dysfunction. Moreover, in perioperative patients, electrolyte monitoring and avoidance of hypertonic fluids are warranted. With regards to blood transfusion, the clinician must not administer it rapidly or in high volumes.
Water or sodium retention
Increased fluid in the intravascular compartment is a consequence of elevated sodium levels and the subsequent increase in water. The following conditions or factors are associated with water or sodium retention.
Cardiac diseases such as CHF promote the production of hypervolemia. In CHF, contractility is impaired, which results in the buildup of blood in the vasculature.
Also, renal causes including kidney failure and glomerulonephritis lead to poor excretion of fluids. Furthermore, albumin deficiency in nephrotic syndrome favors the flux of intravascular fluid into the tissues, which is followed by the physiologic response of water and salt retention.
In the cardiorenal and renocardiac syndromes, there is a complicated interplay between the two organs with respect to regulation of sodium and water [1] [2].
Liver pathologies such as cirrhosis play a role by elevating plasma levels.
Additionally, endocrine diseases such as hyperaldosteronism lead to fluid overload due to the effects of aldosterone.
As for medications, drugs such as corticosteroids and chemotherapy agents may result in fluid and salt retention.
Stress response mechanisms also contribute to the development of hypervolemia. For example, post-operative patients experience an increase in antidiuretic hormone (ADH) secretion, which is a hormone involved in sodium and water reabsorption. The same applies to individuals suffering from a head injury. Additionally, these patients experiencing stress have trouble excreting the excess water and sodium.
Finally, individuals who consume low protein diets are predisposed to hypervolemia.
Fluid shift into the intravascular space
There are conditions in which there is fluid displacement. For example, burn patients treated with albumin, mannitol or hypertonic fluids may undergo fluid remobilization. Moreover, these medications may cause hypervolemia in non-burn patients as well.
Altered physiology
Note that pregnant patients develop significant hemodynamic changes that cause fluid overload. Additionally, a severe disease known as preeclampsia results in critical fluid status changes.
One investigation studied the fluid status of 43 patients with CHF through measurements of the blood volume by utilizing radioisotope [3]. It reported that 65% of the participants demonstrated an increase in volume despite therapy with loop diuretics. Furthermore, the hypervolemic group was linked to a one-year mortality rate of 39% and a two-year rate of 55%. In contrast, there were no deaths in the normal or low volume groups.
Note that there are more than 4.5 million individuals in the United States who have heart failure. Each year, there are more than half a million new cases. Hence, measurement of the blood volume may impact the treatment and prognosis of these patients.
Normal physiology
The total blood volume is the sum of plasma and red blood cells, which is around 5L. The extracellular compartment takes up 15L while the intracellular volume is 25L. Note that administration of saline may affect all spaces. While fluid overload involves the plasma space, other compartments may play a role as well.
Pathophysiology
The fluid shift between the compartments operates under the influence of Starling's Law. For example, fluid outflux occurs when there is both a positive capillary hydrostatic pressure and negative interstitial hydrostatic pressure. In contrast, fluid shift into the blood occurs when the oncotic pressure gradient is greater than the hydrostatic pressure.
Iatrogenic causes can be prevented when clinicians are cautious with IVF resuscitation and blood transfusions especially in high-risk populations such as the elderly, postoperative patients, burn victims, or those affected with underlying conditions such as cardiac or renal failure. Additionally, the NICE guidelines provide algorithms with details regarding the assessment of fluid.
There also specific guidelines provided by the Surviving Sepsis Campaign for critically ill patients with sepsis or shock.
Additionally, special consideration should be applied to oliguric individuals as these patients may or may not have intravascular depletion. The clinician must perform a thorough clinical evaluation of their vitals, capillary refill times, and jugular venous pressure.
Furthermore, clinical correlation should be used in post- surgery oliguria cases so that these patients' fluids can be appropriately managed.
Hypervolemia is a condition in which there is an excess of fluid volume in the intravascular compartment. It is either caused by increased fluid intake, diseases that lead to sodium and water retention, or phenomena that promote the influx of fluid into the plasma. For example, congestive heart failure (CHF), renal failure, and liver failure may lead to impairment of sodium handling. Furthermore, treatment with albumin or hypertonic solutions results in the intravascular shift of fluids.
The clinical picture and physical examination will reflect the abnormal fluid status. Furthermore, the patients will likely exhibit signs and symptoms of pulmonary edema and CHF in addition to features of underlying pathologies.
The clinician should obtain a detailed history and perform a full evaluation of the patient's presentation and physical assessment. Moreover, key laboratory tests and imaging techniques are pertinent components of the workup. The latter will help identify the etiology of the hypervolemia. Prompt diagnosis and treatment are paramount for the prevention of overload progression.
Treatment involves fluid restriction, possible use of diuretic therapy, and dietary modifications. Furthermore, iatrogenic causes such as excessive fluid resuscitation may be avoided with careful treatment especially in the elderly and those with cardiac and renal dysfunction.
What is hypervolemia?
Hypervolemia is the medical condition in which there is too much fluid in the blood. One way this occurs is through blood transfusions or increased intravenous fluids. It also results from mechanisms that lead to increased sodium and water in the blood. Finally, it may be caused by situations that pull water out from the tissues into the blood.
What are the causes of hypervolemia?
When the mechanisms that regulate the water and salt levels in the fluid are impaired, the consequences are fluid overload. Examples of diseases are:
Fluid shift into the intravascular space as caused by:
What are the symptoms?
The signs and symptom manifest as pulmonary edema which is a condition where there is fluid buildup in the lungs. These patients will have shortness of breath while lying down and performing physical activity. They may wake up from sleep due to shortness of breath as well. If they develop a cough, it often produces a pink, frothy sputum. Also, there may be fluid and, therefore, swelling in the legs, feet and arms. Sometimes, there is fluid accumulation in the abdomen, which is a sign known as ascites.
On the physical exam, the clinician will find a fast heart rate, high blood pressure, abnormal heart sounds and maybe murmurs. On the lung exam, the clinician will hear sounds that suggest there is fluid.
Also, these patients may experience confusion and lethargy as well as anxiety.
How is this diagnosed?
The doctor will assess the symptoms, the medical history of the patient, and the physical signs.
The tests will include chest X-ray which shows the fluid in the lungs. Also, an echocardiogram will show the heart function and identify if there are any problems. The electrocardiogram (EKG) will reveal the heart rate and rhythm of the heart and if there are ischemia and enlargement of the heart.
Blood tests will assess the electrolytes, the kidney function, protein levels, and other measurements as well.
How is this treated?
One of the ways this condition is treated is by fluid restriction. Patients have to limit the quantity of fluid they drink. Also, they are highly advised to limit the quantity of salt they eat. They should avoid potato chips, bacon, canned foods, etc. The doctor may also prescribe a diuretic to help them urinate more fluids out.