Acute Renal Failure

ACUTE RENAL FAILURE 

Acute renal failure or Acute kidney failure (AKF) occurs when kidneys suddenly become unable to filter waste products from blood. When kidneys lose their filtering ability, it results in 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 

Acute renal failure can occur when: 

(i) 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 dehydration.

(ii) Damage to the Kidneys:  

 Certain diseases, conditions and agents may damage the kidneys and lead to acute renal failure includes:
•  Blood clots in the veins and arteries in and around the kidneys. 

•  Cholesterol deposits that 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. 

(iii)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.

Pathophysiology 

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 

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

Complications

Potential complications of acute renal failure include:
Fluid build-up: Acute renal failure may lead to a build-up of fluid in chest, which can cause shortness of breath.
Chest pain: If the lining that covers heart becomes inflamed, it may lead to chest pain.
Muscle weakness:When body’s fluids and electrolytes are out of balance, muscle weakness can result. Elevated levels of potassium in 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. 

Treatments and Drugs 

Treatment for Acute renal failure involves identifying the illness or injury that originally damaged kidneys. 

Balance the amount of fluids in blood: If Acute renal failure is caused by a lack of fluids in blood, may recommend intravenous fluids. In other cases, acute renal failure may cause to have too much fluid, leading to swelling in 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 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 recommonded. 

Treatment for end-stage kidney disease: If kidneys cannot keep up with waste and fluid clearance on their own and develop complete kidney failure lead 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 blood when kidneys can no longer perform normally. In hemodialysis, a machine filters waste and excess fluids from the blood. 

Kidney transplant: A kidney transplant involves surgically placing a healthy kidney from a donor into body. Transplanted patient may need to take medications for the rest of life to keep 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 include 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 risk of acute kidney failure, 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.