Intravascular Volume or Plasma Volume is defined as the volume of blood in a patient's circulatory system. It is essentially the blood plasma component of the overall volume status of the body, which otherwise includes both intracellular fluid and extracellular fluid.

Glomerular FiltrationRate (GFR) is a measurement to check how well the kidneys are working. Specifically, it estimates how much blood passes through the glomeruli, or tiny filters in the kidney, each minute.

• eGFR - Estimated Glomerular Filtration Rate indicates the level of kidney function.  It is calculated based on the results of a creatinine serum test and other factors—such as age, gender, muscle mass, and ethnicity.
• mGFR - Measured Glomerular Filtration Rate is considered the gold standard for the measurement of kidney function. It is measured by the clearance of an exogenous ideal marker that is biologically inert and exclusively cleared by glomerular filtration without tubular reabsorption or secretion.

Heart failure is a serious and often life-threatening condition where the heart muscle cannot adequately deliver oxygenated blood throughout the body. This condition often leads to fluid retention, lung congestion, difficulty breathing, and progressive kidney impairment. Heart failure can occur suddenly (acute heart failure), and if it persists, it is designated as chronic heart failure.

Function of the heart and the kidneys is inextricably linked. Cardiorenal syndrome occurs when dysfunction in either the heart or the kidneys lead to dysfunction in the other organ. Like heart failure, cardiorenal syndrome can evolve over a prolonged period of time or it can occur rapidly. Cardiorenal syndrome is a challenging clinical problem that has been associated with higher mortality rates than single organ disease or injury.

Acute Kidney Injury (AKI) is defined as the rapid decline of kidney function over a period of days. AKI is a serious and sometimes irreversible condition that leads to reduced urine production and accumulation of waste products in the blood. Dialysis is often required to help reduce the excessive fluid and waste products from the blood. Causes of AKI include low blood flow to the kidneys, bacterial or viral pathogens, or toxicity caused by some drug or chemical agents.

Chronic Kidney Disease (CKD) is defined as a reduction in kidney function lasting longer than 90 days. Progression of CKD leads to the loss of kidney function over time. Diabetes, high blood pressure, heart failure, and family history are all risk factors for CKD. If CKD progresses to end-stage kidney disease (ESKD) chronic dialysis is required to remove excess fluid and wastes products from the blood. A kidney transplant may also be an option in certain cases.

Acute Respiratory Distress Syndrome (ARDS) occurs when fluid builds up in the lungs and impairs the movement of oxygen from the lungs to the blood. This reduces the amount of oxygen transported to tissue throughout the body. ARDS is a serious and life-threatening condition that can be caused by sepsis, trauma, pneumonia, inhaling toxic substances, or other causes. Treatments for ARDS include mechanical ventilation and supplemental oxygen.

Sepsis is a life-threatening infection that can lead to a severe inflammatory response and a significant decline in organ function. In its most serious form, known as septic shock, a patient will experience a significant decline in blood pressure and a buildup of lactic acid in the body. Sepsis treatment includes supplemental fluids and aggressive use of antibiotics and medicines to increase blood pressure.