One definition of acute renal failure (ARF) is any condition, regardless of the cause or pathogenesis, resulting in sudden suppression of kidney function: decreased glomerular filtration rate (GFR), oliguria (urine output < 400ml/day) or anuria (no urine production; and rapidly increasing levels of creatinine, and nitrogenous waste products in the blood.
The traditional pathophysiologic-anatomic classification takes into account the fact that the kidneys function sequentially by creating an ultra-filtrate of arterial blood, processing this ultra-filtrate by reabsorption or secretion of various electrolytes, water, and metabolic waste products. From this, three (3) major categories of acute renal failure can be defined: prerenal ARF (reduction in renal perfusion), intrinsic renal ARF (acute, severe parenchymal renal damage), and postrenal ARF (think obstruction)
Prerenal- (25% of ARF cases)
This cause may be associated with depletion of fluid and electrolytes, hemorrhage, sepsis, or heart and/or liver failure - even extended periods of nausea and vomiting.
Renal- (65% of ARF cases)
This may be caused by actual structural damage to the internal kidney units. The glomerulus, nephrons, tubules. Nephrotoxic insults can be a common driver of this type of ARF.
Postrenal- (10% of ARF cases)
This may be caused from obstructions in urine flow and the urinary tract specifically, which increases hydrostatic pressure within the tubules. Kidney or ureteral stones can be a common clinical diagnosis associated with this type of ARF. -- See image below.
Treatment modalities for AKI
General management principles for acute kidney injury include determination of volume status, fluid resuscitation with isotonic crystalloid, treatment of volume overload with diuretics, discontinuation of nephrotoxic medications (like Vancomycin - an antibiotic and a very large molecule), and adjustment of prescribed drugs according to renal function. Additional supportive care measures may include optimizing nutritional status and glycemic control. Long term hyperglycemia is really detrimental to your overall kidney function. Your kidneys do pretty well at filtering and reabsorbing glucose levels up to about 180 mg/dl. Anything higher than that and sugar will begin to spill out into your urine.
On the flip side when chronic renal failure (CRF) is corrected, or the pathology continues unabated it will progress to end-stage renal disease (ESRD). These patients typically require dialysis (hemo -or- peritoneal) or renal transplant to survive. There are many types of diseases that may result in CRF. These include but aren't limited to: diabetes (34%), HTN (29%), glomerulonephritis (14%), interstitial nephritis (3%), cystic kidney disease (3%), and a myriad of unknown causes (15-17%).
ESRD treatment modalities
Peritoneal dialysis is performed by surgically placing a special, soft, hollow tube into the lower abdomen near the navel. After the tube is placed, a special solution called dialysate is instilled into the peritoneal cavity. The peritoneal cavity is the space in the abdomen that houses the organs and is lined by two special membrane layers called the peritoneum. The dialysate is left in the abdomen for a designated period of time which could vary. The dialysate fluid absorbs the waste products and toxins through the peritoneum. The fluid is then drained from the abdomen, measured, and discarded.
Hemodialysis can be performed at home or in a dialysis center or hospital by trained health care professionals. A special type of access, called an arteriovenous (AV) fistula, is placed surgically, usually in your arm. This involves joining an artery and a vein together. An external, central, intravenous (IV) catheter may also be inserted, but is less common for long-term dialysis. After access has been established, you will be connected to a large hemodialysis machine that drains the blood, bathes it in a special dialysate solution which removes waste substances and fluid, then returns it to your bloodstream. Due to advent of new therapies the overall long-term outlook for ESRD continues to improve.
February 19, 2024
Author: Joshua Ishmael, MBA, MLS(ASCP)CM, NRP
Pass with PASS, LLC.
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