What is Acute Renal Failure?

March 11 21:45 2019 Print This Article

It is defined as a disorder in which there is a loss of the kidney function. It is a rapid process and is also known as the acute kidney injury. It can occur due to the number of reasons and involve the low blood volume, exposure to toxins and a prostate enlargement. Its diagnosis is based upon the clinical history and a decrease in the production of urine and also shows an increase in the level of blood urea nitrogen and creatinine. It can lead to the number of complications which includes the metabolic acidosis, increase in the potassium levels and changes in the body fluid balance. It affects other organ systems also. It is treated with the help of supportive care which includes the renal replacement therapy and the treatment of underlying disorder.

What is the epidemiology of Acute renal failure ?

This disorder is common among the hospitalized people. It involves 3 to 7 percent of the patients which are admitted to the hospital and one fourth of the patient present in the intensive care unit.

What are the causes of Acute renal failure ?

This disorder includes the causes as divided into pre renal, intrinsic and post renal. The pre renal causes include the decrease in the effective blood flow to the kidney. It includes the low blood volume, low blood pressure and a heart failure. The changes in the blood vessels which supply to the kidney can also lead to this disorder. It includes the renal artery stenosis in which there is a narrowing of the renal artery which supplies the kidney. There is a renal vein thrombosis in which there is a formation of blood clot in the vein that affects blood flow from the kidney. The intrinsic causes include the damage to the kidney by itself. It can occur as damage to the glomeruli, renal tubule and interstitium. The common causes are the AIN, ATN which are referred as acute tubular necrosis and acute interstitial nephritis. The post renal causes include the obstruction of the urinary tract. It is related to the benign prostrate hyper plasia and kidney stones. There is a obstruction in the urinary catheter.

What is the diagnosis of Acute renal failure ?

This disorder includes the diagnosis mainly by the use of clinical history and involves the laboratory data. A rapid reduction in the kidney function gives rise to the diagnosis of this disorder. It is measured by the serum creatinine and is based on the rapid reduction in the urinary output which is known as the oliguria. According to the acute kidney injury network there is a specific criteria which exists for the diagnosis of this disorder. It includes the rapid time course which is less than 48 hrs and there is a reduction in the function of kidney. In this there is a rise in the serum creatinine which is more than or equal to 0.3 mg per deci litre.

The percentage increase in the serum creatinine is more than 50 percent. There is a reduction in the urinary output which is defined as a less than 0.5 ml per kilo gram per hour for more than 6 hours. The RIFLE criteria of staging are done by the acute dialysis quality initiative referred as an ADQI. It helps in the staging of patients with this disorder. In the risk stage there is an increase in the serum creatinine 1.5 times or decreases in the urine production of 0.5 ml per kg for 6 hours. In the injury stage there is a double amount of creatinine or urine production less than 0.5 ml per kg for 12 hours. In the failure stage there is an tripling of creatinine more than 355 micro mol per litre which can rise up to 44. The urinary output can below the 0.3 ml per kg for 24 hours. In the loss stage there is an persistent and complete loss of kidney function for more than 28 days.

In the end stage renal disease there is a complete loss of kidney function for more than 90 days. There is a need of further testing as the diagnosis is confirmed. It can be done with the help of renal ultra sound biopsy and kidney biopsy. The indication for the renal biopsy involves the unexplained AKI, AKI in the presence of nephritic syndrome and systemic disease linked with the AKI.

What is the treatment of Acute renal failure ?

This disorder includes the identification and treatment of underlying cause. One must avoid the substances which are toxic to kidneys and are referred as nephrotoxins. It includes the NSAIDs like ibuprofen and the use of iodinated contrasts like the CT scans and others. One can monitor the function of kidney by serum creatinine and must monitor the urine output. The insertion of urinary catheter in the hospitals helps to know about the urinary output. It relieves the bladder obstruction and is done in the case of enlarged prostrate.

In the pre renal AKI which is without the fluid overload one can go for the intra venous fluids which can improve the renal function. The fluid administration can be monitored with the help of central venous catheter. It avoids the over and under displacement of the fluid. If there is a continuous low blood pressure in the patient it can lead to the fluid replete patients and one can give the inotropes like nor epinephrine and dobutamine to improve the cardiac output. It also improves the renal perfusion. There is no evidence which can suggest a dopamine of any benefit but it can be harmful also.

The cause of intrinsic AKI needs specific therapies. It may occur due to the wegners granulomatosis and may respond to the steroids. The toxic induced pre renal AKI responds to the discontinuation of the agent which causes this trouble. It includes NSAIDs, penicillin, amino glycosides and acetaminophen. The use of diuretics does not alter the risk of complication or death. It is useful in decreasing the fluid over load. It masks the things which make it difficult for the resuscitation. There is a renal replacement therapy which involves the hemo dialysis. It can be done in some cases of this disorder.

A systematic review done in the year 2008 indicated that there was no difference in the outcome between the use of intermittent and continuous hemo dialysis and hemo filtration referred as a CVVH. In the critical ill patients an intensive renal replacement therapy with CVVH does not improve the outcome as compared to less intensive intermittent hemo dialysis.

What are the complications of acute renal failure ?

The most common complications of this disorder are the metabolic acidosis and hyper kalemia. They need medical treatment and the use of sodium bi carbonate with the anti hyper kalemic measures unless there is no need of dialysis. One may need a artificial support in the form of dialysis or hemo filteration. It can work when there is no improvement with the other methods which involve the fluid resuscitation, therapy resistant hper kalemia and metabolic acidosis with fluid over load. Most of the patients never regain the full renal function depending on the cause and have a end stage renal failure which requires a use of lifelong dialysis with a kidney transplant.

What is the history of acute renal failure ?

This disorder was referred as a uremic poisoning before the introduction of modern medicine. Uremia was used to describe the contamination of blood with the urine. The term oliguria in the year 1847 was used to describe the urine output and was thought to be caused by the mixing of urine with blood instead of it passing through the urethra. An acute kidney injury due to the ATN was recognized in the 1940 in UK where crush injury victims during the battle of Britain developed a necrosis of the renal tubules. It leads to sudden decrease in the renal function. In the Korean and Vietnam war the incidence of AKI decreased by the better management and the use of intra venous fluids.

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