DescriptionSurgical Other Kidney and Urinary Tract Operating Room Procedures

^Acute renal failure (ARF) is the abrupt deterioration of renal function that results in the accumulation of fluids, electrolytes, and metabolic waste products. It is usually accompanied by a marked decrease in urinary output. Although ARF is often reversible, if it is ignored or inappropriately treated, it can lead to irreversible kidney damage and chronic renal failure. Two types of ARF occur: community- and hospital-acquired. Community-acquired ARF is diagnosed in about 1% of hospital admissions at the time of initial assessment. In comparison, hospital-acquired ARF occurs in up to 4% of hospital admissions and 20% of critical care admissions. There are many reasons for this increased incidence of hospital-acquired ARF, and they include an aging population, the use of nephrotoxic medications, and increasing severity of illness in hospitalized patients.

Approximately 70% of patients develop oliguric ARF with a urine output < 500 mL/day. The other 30% of patients never develop oliguria and have what is considered nonoliguric renal failure. Oliguric ARF generally has three stages. During the initial phase (often called the oliguric phase), when trauma or insult affects the kidney tissue, the patient becomes oliguric. This stage may last a week or more. The second stage of ARF is the diuretic phase, which is heralded by a doubling of the urinary output from the previous 24 hours. During the diuretic phase, patients may produce as much as 5 L of urine in 24 hours but lack the ability for urinary concentration and regulation of waste products. This phase can last from 1 to several weeks. The final stage, the recovery phase, is characterized by a return to a normal urinary output (about 1500 to 1800 mL/24 hr), with a gradual improvement in metabolic waste removal. Some patients take up to a year to recover full renal function after the initial insult.

Complications of ARF include severe electrolyte imbalances such as hyperkalemia and hypocalcemia. The patient is also at risk for secondary infections, congestive heart failure, and pericarditis. ARF that does not respond to treatment of the underlying cause can progress to chronic renal failure (CRF; see the next chapter).

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