Acute renal failure (ARF), also known as acute kidney injury, results in decreased kidney function (reduced glomerular filtration rate) over a relatively short period of time. This could occur as an acute-on-chronic phenomenon.
Causes of Renal Failure
In usual scenarios, renal /kidney failure is caused due to certain infection related illness. There would be no symptoms shown by the patients having an intrinsic renal disease or low-grade chronic obstruction.
Here are three categories listed below which could cause acute kidney injuries like:
- Prerenal acute kidney injury.
- Intrinsic acute renal injury.
- Post-renal Intrinsic renal injury.
Prerenal kidney injury.
A pre-renal failure, which is caused mainly by the reduction in the blood flow to the kidney. It is not due to the direct damage of the nephron itself, owing to the inability to maintain renal blood flow which results from the kidney injury. Other factors resulting in pre-renal failure are:
- Gastroenteritis, or loss of blood,
- Vasodilation caused by the drugs reaction,
- Active hypovolemia sepsis,
- Decreased cardiac output,
- Addisonian crisis,
- Salt wasting syndrome,
- Protein-losing enteropathy,
- Altered hemodynamics or dynamics of blood flow caused by dehydration,
- Deficiency of blood in kidneys by– Intrarenal redistribution, mainly caused by, vasoconstrictors, anesthesia, stress, surgery,
Intrinsic renal injury
The intrinsic renal injury is characterized by direct damage to the nephrons. It is often complex and may be secondary to another illness. Prerenal etiologies noted above could lead to acute tubular necrosis (ATN). Additional causes –
- Vasculitis (polyarteritis nodosa, Lupus, Wegener’s granulomatosis),
- Microangiopathic states (hemolytic uremic syndrome, DIC, TTP),
- Glomerulonephritis (acute post-streptococcal and others).
The post-renal injury is caused by a blockage to the flow of urine, resulting in a back pressure to the kidney, which causes damage to
- Posterior urethral valves.
- Urethral strictures – narrowing of urethra
- Bladder obstruction from clots (hemorrhagic cystitis),
- Formation of ureteral stones.
Prevention and Treatment of Renal Failure
As per the outcome of established renal /kidney failure, prevention is critical. In certain cases, the risk of developing renal failure could be predicted such as decreased perfusion secondary to abdominal surgery, coronary bypass surgery, acute blood loss in trauma, and uric acid nephropathy, where preventative strategies could prove effective. When patients with risk factors for developing renal failure are scheduled for surgery, the doctor should be aware that the likelihood of the patient developing the renal failure is high and consider preventative measures, including discontinuation of medications that might enhance the likelihood of renal damage (e.g., NSAIDs, angiotensin-converting enzyme inhibitors).
A novel approach for reducing the incidence of nephrotoxicity associated with radiocontrast dye administration is to provide prophylactically to patients who are at a high risk of acute renal failure.
Hemofiltration initiated prior to and continued for 24 hours after dye administration has resulted in a significant reduction in mortality and a reduced need for dialysis.
Dopamine and Diuretics
Given the dismal outcome of established of acute renal failure, many drugs have been investigated for its prevention. Almost all of these approaches have been shown to be of little to no value. Low doses of dopamine (≤ 2 mcg/kg/min) increases renal blood flow and might be expected to increase GFR (glomerular filtration rate). Theoretically, this could be considered beneficial, as an enhanced GFR (glomerular filtration rate) might flush nephrotoxins from the tubules, minimizing their toxicity.
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