8.5 Acute Renal Failure
Acute renal failure (also known as acute kidney injury) is the sudden loss of kidney function. Acute renal failure can be reversible if it is detected early, and intervention is promptly initiated. The condition can happen over a few hours to a few days and reflects the rapid decline in the kidney’s ability to filter waste products and fluids from the blood, resulting in a buildup of waste products and toxins in the blood.
Pathophysiology and Risk Factors
Acute renal failure is the result of three main types of injury to the kidneys referred to as prerenal, intrarenal, and postrenal:
- Prerenal: Prerenal injury is caused by factors external to the kidneys that reduce renal blood flow, resulting in decreased glomerular perfusion and filtration. Examples of prerenal factors are hypovolemia, decreased cardiac output, and vascular obstruction that decrease the amount of circulating volume of blood to the kidneys.
- Intrarenal: Intrarenal injury is caused by conditions that directly damage the renal tissue, resulting in impaired nephron function. Examples of intrarenal injury are prolonged ischemia to the kidneys, nephrotoxins (such as aminoglycoside antibiotics and contrast media), excess hemoglobin released from hemolyzed RBCs, or myoglobin released from necrotic muscle cells.
- Postrenal: Postrenal injury is caused by mechanical obstruction of urinary outflow, resulting in the reflux of urine into the renal pelvis and impaired kidney function. Examples of postrenal injury include benign prostatic hyperplasia, prostate cancer, kidney stones, trauma, and tumors in the urinary tract.
See Figure 8.13[1] for an image of these types of acute renal failure.
Several factors can increase the risk of developing acute renal failure. Acute renal failure is more common in aging individuals due to a natural decline in kidney function. Individuals with underlying health conditions such as chronic kidney disease, diabetes, hypertension, heart failure, liver disease, and autoimmune disorders are also at increased risk. Risk also increases for individuals experiencing dehydration, blood loss/trauma, severe infections, or exposure to toxins.[2],[3]
Assessment
Common symptoms of acute renal failure across body systems are summarized in Table 8.5.
Table 8.5. Manifestations of Acute Renal Failure Across Body Systems[4],[5],[6]
| Body System | Clinical Manifestations of Acute Renal Failure |
|---|---|
| Renal | Oliguria, anuria, and uremia (elevated urea and nitrogenous waste in the blood) |
| Cardiovascular | Hypertension, fluid overload, pitting edema, heart failure, arrhythmias, and pericarditis |
| Respiratory | Dyspnea (shortness of breath from pulmonary edema) and Kussmaul breathing (in severe metabolic acidosis) |
| Gastrointestinal | Nausea, vomiting, anorexia, gastrointestinal bleeding, and gastritis |
| Neurological | Confusion, asterixis (flapping tremor), peripheral neuropathy, seizures, and coma |
| Hematological | Anemia (due to decr