Volatile anesthetic agents have been shown to increase renal sympathetic nerve activity (RSNA), which causes retention of salts and water, diminished renal blood flow (RBF) and an increase in serum renin levels, but not in antidiuretic hormone (ADH). Treatment
The management of AKI hinges on identification and treatment of the underlying cause. The main objectives of initial management are to prevent cardiovascular collapse and death and to call for specialist advice from a nephrologist. In addition to treatment of the underlying disorder, management of AKI routinely includes the avoidance of substances that are toxic to the kidneys, called nephrotoxins. These include NSAIDs such as ibuprofen or naproxen, iodinated contrasts such as those used for CT scans, many antibiotics such as gentamicin, and a range of other substances.Monitoring of kidney function, by serial serum creatinine measurements and monitoring of urine output, is routinely performed. In the hospital, insertion of a urinary catheter helps monitor urine output and relieves possible bladder outlet obstruction, such as with an enlarged prostate. Prerenal
In prerenal AKI without fluid overload, administration of intravenous fluids is typically the first step to improving kidney function. Volume status may be monitored with the use of a central venous catheter to avoid over- or under-replacement of fluid.
For instance, it takes about 24 hours for the creatinine level to rise, even if both kidneys have ceased to function. A number of alternative markers have been proposed (such as NGAL, KIM-1, IL18 and cystatin C), but none of them are established enough as of 2018 to replace creatinine as a marker of kidney function.Once the diagnosis of AKI is made, further testing is often required to determine the underlying cause. It is useful to perform a bladder scan or a post void residual to rule out urinary retention. In post void residual, a catheter is inserted into the urinary tract immediately after urinating to measure fluid still in the bladder. 50–100 mL suggests neurogenic bladder dysfunction. These may include urine sediment analysis, renal ultrasound and/or kidney biopsy. Indications for kidney biopsy in the setting of AKI include the following:
Unexplained AKI, in a patient with two non-obstructed normal sized kidneys. AKI in the presence of the nephritic syndrome. Systemic disease associated with AKI. Kidney transplant dysfunction.In medical imaging, the acute changes in the kidney are often examined with renal ultrasonography as the first-line modality, where CT scan and magnetic resonance imaging (MRI) are used for the follow-up examinations and when US fails to demonstrate abnormalities. In evaluation of the acute changes in the kidney, the echogenicity of the renal structures, the delineation of the kidney, the renal vascularity, kidney size and focal abnormalities are observed.