Acute Renal Failure
Acute renal failure is a sudden and rapid decrease in renal function. This condition can develop as a consequence of prerenal, intrarenal, or postrenal disorders. Prerenal disorders are disorders that disrupt blood flow to the nephrons, these are nonurologic factors. Intrarenal conditions are ones that arise in the kidney itself, causing the destruction of the nephrons. Postrenal are factors that occur in the structures below the kidney causing an obstruction and therefore destruction of the nephrons.
There are four stages one goes through with acute renal failure. These are listed below:
1. Initiation phase
2. Oliguric phase
3. Diuretic phase
4. Recovery phase
The initiation phase is the onset of the contributing event. Its manifestation is the reduced blood flow to the nephrons. This is to the extent of tubular necrosis. This causes decreased reabsorption of water, electrolytes, and excretion of protein wastes and excess metabolic substances.
The oliguric phase is characterized by excretion of less than adequate urinary volumes. It begins within 48 hours after the initial onset and lasts from 10 – 14 days or longer. Edema, hypertension, and cardiopulmonary complications are caused by excess fluid volume. Azotemia is the accumulation of urea and other nitrogenous wastes such as creatinine and uric acid in the blood. This creates a potential for neurologic changes such as seizures, coma, and death.
Diuresis begins as the nephrons recover. The excretion of wastes and electrolytes continues to be impaired even though there is more urine being produced. The blood levels of BUN, creatinine, potassium, and phosphate levels remain elevated.
The recovery phase is characterized by the recovery of the nephrons. It may take one or more years to restore normal filtration and function. Some recover completely and some retain some form of renal impairment.
Signs and symptoms include elevated blood pressure and weight gain and decreased urine output. The medical management of acute renal failure is the prevention. Keeping clients well hydrated, treating shock and hypotension, and treating infections quickly and thoroughly are very important in the prevention of ARF.
If it is not caught before it develops measures are taken to remedy the primary cause of failure. Damage can be limited by aggressively administering parenteral fluids to increase plasma volume, giving vasodilating and diuretic drugs, and infusing dopamine to improve cardiac output and perfuse the renal arteries.
To lessen the effects of the causative factor dialysis may be performed. There are two kinds, hemodialysis where the blood is filtered through a machine, and peritoneal dialysis where fluids and electrolytes are removed by osmosis and diffusion across the peritoneum. Fluid and dietary restrictions are enforced. These include low protein, high calories, low sodium, and low potassium are required. Acid – base balance is restored by administering IV sodium bicarbonate if renal function is insufficient to do so.
