Acute Kidney Failure Health Article

Diagnosis

Kidney failure is diagnosed by a doctor, whether the patient is in the hospital or seen as an outpatient. He or she will take a complete medical history and make a thorough review of the patient's medical record, looking for exposure to nephrotoxic (medicines that can be hard on the kidneys) drugs or other clues to the patient's condition. The physician will then conduct a thorough physical examination, making a careful assessment of the patient's ECF volume and effective circulating blood volume (EBV). A nephrologist, a doctor that specializes in the kidney, may be consulted to confirm the diagnosis and recommend treatment options. He or she will look for a recent history of changes in body weight and try and determine whether the patient is taking in much more fluid than he or she is excreting. Capillary wedge pressure and cardiac output values are also effective tools in pinpointing the cause and extent of the AKF.

The patient that is suspected of having AKF will have blood and urine tests to determine the level of kidney function. A blood test will assess the levels of creatinine, blood urea nitrogen (BUN), uric acid, phosphate, sodium, and potassium. The kidney regulates these agents in the blood. Urine samples will also be collected, usually over a 24-hour period, to assess protein loss and/or creatinine clearance.

Determining the cause of kidney failure is critical to proper treatment. Prerenal or obstructive causes are often looked into first because they are the quickest types of AKF to treat. A full assessment of the kidneys is necessary to determine if the underlying disease is treatable and if the kidney failure is chronic or acute. X rays, magnetic resonance imaging (MRI), computed tomography scan (CT), ultrasound, renal biopsy, and/or arteriogram of the kidneys may be used to determine the cause of kidney failure and level of remaining kidney function. X rays and ultrasound of the bladder and/or ureters may also be needed.

Treatment

Treatment for AKF varies, since it is directed to the underlying, primary medical condition that triggered thekidney failure. Prerenal conditions may be treated with replacement fluids given through a vein, diuretics, blood transfusion, restricted salt intake, or medications. Postrenal conditions and intrarenal conditions may require surgery and/or medication.

Frequently, patients in AKF require hemodialysis, hemofiltration, or peritoneal dialysis to filter fluids and wastes from the bloodstream until the primary medical condition can be controlled.

Hemodialysis

Hemodialysis involves circulating the patient's blood outside of the body through an extracorporeal circuit (ECC), or dialysis circuit. The ECC is made up of plastic blood tubing, a filter known as a dialyzer (or artificial kidney), and a dialysis machine that monitors and maintains blood flow and administers dialysate. Dialysate is a sterile chemical solution that is used to draw waste products out of the blood. The patient's blood leaves the body through the vein and travels through the ECC and the dialyzer, where fluid removal takes place.

During dialysis, waste products in the bloodstream are carried out of the body. At the same time, electrolytes and other chemicals are added to the blood. The purified, chemically-balanced blood is then returned to the body.

A dialysis "run" typically lasts three to four hours, depending on the type of dialyzer used and the physical condition of the patient. Dialysis is used several times a week until AKF has resolved.

Blood pressure changes associated with hemodialysis may pose a risk for patients with heart problems. Peritoneal dialysis may be the preferred treatment option in these cases.

Hemofiltration

Hemofiltration, also called continuous renal replacement therapy (CRRT), is a slow, continuous blood filtration therapy used to control acute kidney failure in critically ill patients. These patients are typically very sick and may have heart problems or circulatory problems. They cannot endure the rapid filtration rates of hemodialysis. They also frequently need antibiotics, nutrition, vasopressors, and other fluids given through a vein to treat their primary condition. Because hemofiltration is continuous, prescription fluids can be given to patients in kidney failure without the risk of fluid overload.

Like hemodialysis, hemofiltration uses an ECC. A hollow fiber hemofilter is used instead of a dialyzer to remove fluids and toxins. Instead of a dialysis machine, a blood pump makes the blood flow through the ECC. The volume of blood circulating through the ECC in hemofiltration is less than that in hemodialysis. Filtration rates are slower and gentler on the circulatory system. Hemofiltration treatment will generally be used until kidney failure is reversed.