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Acute Kidney Injury
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Formerly known as acute renal failure, acute kidney injury (AKI) is a reversible rapid reduction in glomerular filtration rate (GFR) or kidney function, resulting in an increase in serum blood urea nitrogen (BUN), creatinine, and metabolic waste products (Okusa & Rosner, 2022). If left untreated, AKI can lead to reduced urine output, fluid retention, volume overload, and chronic kidney disease.
Definition (Kellum & Lameire, 2012)
The Kidney Disease: Improving Global Outcomes (KDIGO) organization (Kellum & Lameire, 2012) defines AKI as
any of the following:
- Increase in serum creatinine (SCr) by greater than or equal to 0.3 mg/dL (25.6 µmol/L) within 48 hours
- Increase in SCr greater than or equal to 1.5 times baseline, which is known or presumed to have occurred within the prior 7 days
- Urine volume less than 0.5 mL/kg/hour for 6 hours
Classifications of Acute Kidney Injury
(Lippincott Advisor, 2022) |
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Prerenal |
Intrarenal
(Intinsic) |
Postrenal |
Pathophysiology |
Decreased blood flow to kidneys |
Structural injury that causes vessel constriction within the kidney |
Blockage along the urinary tract obstructing urine outflow from the kidney |
Causes |
- Injury or trauma to the back
- Massive fluid loss (vomiting, diarrhea, bleeding, or dehydration)
- Systemic vasodilation and hypotension caused by sepsis, anaphylaxis, anesthesia, drug overdose
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- Acute tubular necrosis
- Coagulation defect
- Malignant hypertension
- Infection and inflammation
- Leukemia, lymphoma
- Medications (antibiotics, nonsteroidal anti-inflammatory drugs)
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- Kidney stones
- Blood clots
- Hematoma
- Prostate enlargement
- Fibrosis tumors
- Genetic anatomic narrowing
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Contrast-induced AKI (CI-AKI) (Kellum & Lameire, 2012)
CI-AKI may occur in patients who receive iodinated radiocontrast for procedures. Patients should be screened for risk factors such as: advanced age, diabetes, hypertension, congestive heart failure, chronic kidney disease, volume depletion, hemodynamic instability, concurrent nephrotoxic medication use and use of large volume and/or high osmolality contrast agents. To minimize risk, consider these strategies:
- Consider alternative methods of imaging studies.
- Use low dose iso-osmolar or low-osmolar contrast medium through an intravenous (IV) route.
- Begin IV fluids (isotonic sodium chloride or sodium bicarbonate) at least one hour before administration of contrast media and continue for 3 to 6 hours after administration to achieve urine output greater than 150 mL/hour in 6 hours.