Introduction of Acute Renal Failure:
Table of Contents
Acute renal failure or Acute kidney failure (AKF) occurs when kidneys suddenly become unable to filter waste products from the blood. When kidneys lose their filtering ability, it results in the accumulation of nitrogenous wastes and fluid and electrolyte imbalance. Acute renal failure is also called acute kidney injury (AKI). It develops rapidly over a few hours or a few days.
Epidemiology:
Acute kidney injury is common among hospitalized patients particularly in critically ill people who need intensive care. It affects some 3-7% of patients admitted to the hospital and approximately 25-30% of patients in the intensive care unit.
Causes of Acute renal failure:
Acute renal failure can occur when:
1. Impaired Blood Flow to the Kidneys:
Diseases and conditions that may slow blood flow to the kidneys and lead to kidney failure include
- Blood or fluid loss.
- Blood pressure medications.
- Heart attack.
- Heart disease.
- Infection.
- Liver failure.
- Use of Aspirin, Ibuprofen and Naproxen.
- Severe allergic reaction (anaphylaxis).
- Severe burns.
- Severe dehydration.
2. Damage to the Kidneys:
Certain diseases, conditions, and agents that may damage the kidneys and lead to acute renal failure include:
- Blood clots in the veins and arteries in and around the kidneys.
- Cholesterol deposits block blood flow in the kidneys.
- Glomerulonephritis, inflammation of the tiny filters in the kidneys (glomeruli).
- Hemolytic uremic syndrome, a condition that results from premature destruction of red blood cells.
- Lupus, an immune system disorder causing glomerulonephritis.
- Medications, such as certain chemotherapy drugs, antibiotics, dyes used during imaging tests, and zoledronic acid, are used to treat osteoporosis and high blood calcium levels (hypercalcemia).
- Multiple myeloma, a cancer of the plasma cells.
- Scleroderma, a group of rare diseases affecting the skin and connective tissues.
- Thrombotic thrombocytopenic purpura (TTP), a rare blood disorder.
- Toxins, such as alcohol, heavy metals, and cocaine.
- Vasculitis, an inflammation of blood vessels.
3. Urine Blockage in the Kidneys:
Diseases and conditions that block the passage of urine out of the body (urinary obstructions) and can lead to acute renal failure include:
- Bladder cancer,
- Blood clots in the urinary tract,
- Cervical cancer,
- Colon cancer,
- Enlarged prostate,
- Kidney stones,
- Nerve damage involving the nerves that control the bladder,
- Prostate cancer.
Etiologic Mechanisms in Acute Renal Failure:
Table: Etiologic mechanisms in ARF
| Prerenal Failure Mechanism: Reduced renal blood flow Severe dehydration shock (all forms) Cardiac failure Renal artery stenosis Renal artery embolism or thrombosis Sickle cell crisis |
| Intrarenal Failure Mechanism: Renal parenchymal disease Ischemic necrosis Nephrotoxicity Autoimmune or is immune disorders Hypertensive nephropathy Diabetic nephropathy Renal trauma Acute glomerulonephritis Vasculitis Acute interstitial nephritis, Rhabdomyolysis |
| Postrenal Failure Mechanism: Prevention of Filtration Due to High tubular pressure (obstructed outflow) Urolithiasis Renal-urinary neoplasms Congenital obstructive uropathies Detrusor areflexia Surgical trauma to ureters Obstructive lymphadenopathy |
Risk Factors of Acute renal failure:
Acute renal failure almost always occurs in connection with another medical condition or event. Conditions that can increase the risk of acute renal failure include:
- Being hospitalized, especially for a serious condition that requires intensive care,
- Advanced age,
- Blockages in the blood vessels in arms or legs (peripheral artery disease),
- Diabetes,
- High blood pressure,
- Heart failure,
- Kidney diseases,
- Liver diseases.
Pathophysiology of Acute renal failure:
The driving force for glomerular filtration is the pressure gradient from the glomerulus to the Bowman space. Glomerular pressure depends primarily on renal blood flow (RBF) and is controlled by the combined resistances of renal afferent and efferent arterioles. Regardless of the cause of AKI, reductions in RBF represent a common pathologic pathway for decreasing glomerular filtration rate (GFR). The etiology of AKI consists of 3 main mechanisms: prerenal, intrinsic, and obstructive.
In prerenal failure, GFR is depressed by compromised renal perfusion. Tubular and glomerular function remain normal.
Intrinsic renal failure includes diseases of the kidney itself, predominantly affecting the glomerulus or tubule, which are associated with the release of renal afferent vasoconstrictors. Ischemic renal injury is the most common cause of intrinsic renal failure. Patients with chronic renal failure may also present with superimposed AKI from prerenal failure and obstruction, as well as intrinsic renal disease.
Obstruction of the urinary tract initially causes an increase in tubular pressure, which decreases the filtration driving force. This pressure gradient soon equalizes, and maintenance of a depressed GFR then depends on renal efferent vasoconstriction.
Symptoms of Acute renal failure:
Signs and symptoms of acute renal failure may include:
- Decreased urine output, although occasionally urine output remains normal,
- Fluid retention, causing swelling in legs, ankles, or feet,
- Drowsiness,
- Shortness of breath,
- Fatigue,
- Confusion,
- Nausea,
- Seizures or coma in severe cases,
- Chest pain or pressure.
Sometimes Acute renal failure causes no signs or symptoms and is detected through lab tests done for another reason.
Complications:
Potential complications of acute renal failure include:
Fluid build-up: Acute renal failure may lead to a build-up of fluid in the chest, which can cause shortness of breath.
Chest pain: If the lining that covers the heart becomes inflamed, it may lead to chest pain.
Muscle weakness: When the body’s fluids and electrolytes are out of balance, muscle weakness can result. Elevated levels of potassium in the blood are particularly dangerous.
Permanent kidney damage: Occasionally, Acute renal failure causes permanent loss of kidney function or end-stage renal disease.
Death: Acute renal failure can lead to loss of kidney function and, ultimately death. The risk of death is highest in people who had kidney problems before acute kidney failure.
Tests And Diagnosis:
Urine output measurements: The amount of urine excreted in a day may help to determine the cause of kidney failure.
Urine tests: Analyzing a sample of urine, may reveal abnormalities that suggest kidney failure.
Blood tests: A blood sample may reveal rapidly rising levels of urea and creatinine.
Imaging tests: Imaging tests such as ultrasound and computerized tomography may be used to help with any abnormalities in the kidneys.
Biopsy: In certain situations, a kidney biopsy may recommend removing a small sample of kidney tissue for lab testing.
Treatments and Drugs of Acute renal failure:
Treatment for Acute renal failure involves identifying the illness or injury that originally damaged kidneys.
Balance the number of fluids in blood: If Acute renal failure is caused by a lack of fluids in the blood, may recommend intravenous fluids. In other cases, acute renal failure may cause to have too much fluid, leading to swelling in the arms and legs. In these cases, diuretics may use.
Medications to control blood potassium: If potassium is not properly filtering from blood, may require calcium, glucose, or sodium polystyrene sulfonate to prevent the accumulation of high levels of potassium in the blood. Too much potassium in the blood can cause dangerous arrhythmias and muscle weakness.
Medications to restore blood calcium levels: In hypocalcemia, calcium infusion is recommended.
Treatment for end-stage kidney disease: If kidneys cannot keep up with waste and fluid clearance on their own and develop complete kidney failure leads to end-stage kidney disease. At that point, dialysis or a kidney transplant is needed.
Dialysis: Dialysis artificially removes waste products and extra fluid from the blood when kidneys can no longer perform normally. In hemodialysis, a machine filters waste and excess fluids from the blood.
In peritoneal dialysis, a thin tube (catheter) inserted into the abdomen fills the abdominal cavity with a dialysis solution that absorbs waste and excess fluids. After some time, the dialysis solution drains from the body, carrying the waste with it.
Kidney transplant: A kidney transplant involves surgically placing a healthy kidney from a donor into the body. The transplanted patient may need to take medications for the rest of their life to keep the body from rejecting the new organ.
Prevention:
Acute renal failure is often difficult to predict or prevent. But may reduce risk by taking care of kidneys.
Yearly physical examination includes blood tests and urinalysis to monitor kidney and urinary tract health.
Drink enough fluids to keep the kidneys functioning properly.
Avoid taking substances or medications that can poison or damage kidney tissues.
Patients having other diseases or conditions that increase the risk of acute kidney failures, such as diabetes or high blood pressure, must follow recommendations for managing these conditions. Persons at risk for chronic renal failure may need more frequent testing for kidney function and other problems that occur with declining kidney function.
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