Acute Kidney Injury (AKI)

 Acute Kidney Injury (AKI)

Acute kidney injury (AKI) is a sudden reduction in renal function causing disturbances in electrolytes, fluids, and acid-base balance which increases the risk for mortality especially in critically ill patients. 

How is Acute Kidney Injury diagnosed?  

The Kidney Disease Improving Global Outcomes (KDIGO) clinical practice guidelines, enumerates three criteria for diagnosing acute kidney injury (AKI). Only 1 criterion is enough to define acute kidney injury in a patient. The criteria are  

1.  serum creatinine increase of 0.3 mg/dL or more within 48 hours. 

2. AKI can also be defined as a serum creatinine increase to 1.5 times baseline or more within the last 7 days, 

3.  or urine output less than 0.5 mL/kg/h for 6 hours

What causes Acute Kidney Injury?

Causes of AKI may be prerenal, intrinsic, or post renal. 

Examples of pre-renal etiologies for AKI are volume redistribution as in sepsis, decreased cardiac output, medications that limit glomerular filtration.

Intrinsic etiologies can be vascular, acute tubular necrosis (ATN), acute interstitial nephritis (AIN), neurotoxins, Thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS), glomerular disease. 

Post-renal etiologies include blood clots, stones, malignancy, bladder outlet obstruction, neurogenic bladder, posterior urethral valves (PUV), and iatrogenic. 

Acute kidney injury can lead to acute renal failure (ARF)if not treated.

Indications for hemodialysis in ARF are as follows and follows the mnemonic 

AEIOU. 

A is for acidosis, 

E is for electrolytes such as hyperkalemia, 

I is for intoxication, 

O is for overload, 

U is for uremia.

There are a number of nephrotoxic drugs that should be avoided because they can cause acute kidney injury in the critically ill.  Examples of these are, non-steroidal anti-inflammatory drugs, Antibiotics (aminoglycosides, amphotericin, acyclovir), ACE-inhibitors, and radiocontrast dye. Other dialyzable drugs/toxins follow the mnemonic ISTUMBLED

I- INH, isopropyl alcohol

S- Salicylates

T- Theophylline

U- Uremia

M- Methanol

B- Barbiturates

L- Lithium

E- Ethylyne Glycol

D- Dabigatran (Pradaxa), Divalproex (Depakote)

Acute kidney injury is common in our critically ill and emergency care patients and, whenever possible, avoid nephrotoxic medications that can result in additional injury. 

Please watch the video on Understanding Acute Kidney Injury 2024 05 23

References: 

Patel JB, Sapra A. Nephrotoxic Medications. [Updated 2023 Jun 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK553144/

https://www.ncbi.nlm.nih.gov/books/NBK553144/figure/article-25714.image.f1/?report=objectonly

https://www.ncbi.nlm.nih.gov/books/NBK553144/figure/article-25714.image.f2/?report=objectonly