Perioperative Acute Kidney Injury

Sam D. Gumbert, M.D.; Felix Kork, M.D., M.Sc.; Maisie L. Jackson, M.D.; Naveen Vanga, M.D.; Semhar J. Ghebremichael, M.D.; Christy Y. Wang, M.D.; Holger K. Eltzschig, M.D., Ph.D.

Disclosures

Anesthesiology. 2019;132(1):180-204. 

In This Article

Acute Kidney Injury Definition

Acute kidney injury is one of a number of acute kidney diseases occurring in the presence or absence of other acute or chronic renal disease processes.[7] A condition that affects kidney structure and function is categorized as acute or chronic, based upon interval of time. An inclusive nomenclature to enhance understanding and communication has been proposed to systematically classify functional and structural criteria for acute kidney injury, acute kidney disease, chronic kidney disease, and no known kidney disease (Supplementary Digital Content, http://links.lww.com/ALN/C55).[7]

The publication of Risk, Injury, Failure, Loss, End-stage renal disease criteria (RIFLE) in 2004 created a standard, widely used definition for acute kidney injury.[8] The establishment of these standards ended a plethora of over 35 definitions for acute kidney injury in acute renal failure literature.[9] These standardized criteria established a uniform manner to define acute kidney injury, improving accuracy in reporting incidence and outcomes and allowing comparability of studies regarding the diagnosis of acute kidney injury. This allowed our understanding to evolve from a "simple loss of function" to a more mature reality where acute kidney injury is a multifaceted, heterogeneous disease process.[10,11] However, a significant limitation of the Risk, Injury, Failure, Loss, End-stage renal disease standards is that it underestimated the effect of small acute creatinine changes on mortality as part of the criterion.[12] In response to this shortcoming, the Acute Kidney Injury Network (AKIN) modified the Risk, Injury, Failure, Loss, End-stage criteria, taking into account small increases in creatinine (at least 0.3 mg/dl) over time (at least 48 h) (Table 1).[13] In 2012, the Kidney Disease Improving Global Outcomes (KDIGO) task force offered a cohesive interpretation of the Risk, Injury, Failure, Loss, End-stage renal disease criteria, Acute Kidney Injury Network, and pediatric Risk, Injury, Failure, Loss, End-stage renal disease criteria (pRIFLE) as "a single definition for practice, research, and public health."[14] The Kidney Disease Improving Global Outcomes classification stages the presence of acute kidney injury from an acute increase in serum creatinine or a period of oliguria.[15] As it relates to time, the Acute Dialysis Quality Initiative Group recently clarified that "acute kidney injury" occurs within 48 h or less, and "acute kidney disease" occurs when acute kidney injury persists for 7 days or longer.[15]

Acute kidney injury has two subgroups, "subclinical acute kidney injury" and "functional acute kidney injury," and has recently been described with the introduction of biomarkers as a diagnostic tool.[16] Elevated concentrations of an acute kidney injury biomarker, without meeting Kidney Disease Improving Global Outcomes classifications, is defined as subclinical acute kidney injury, whereas functional acute kidney injury meets the Kidney Disease Improving Global Outcomes definition but fails to demonstrate an increase in biomarker concentration.[17] Although it is tempting to assume that subclinical acute kidney injury is an innocuous phenomenon with surgical patients, current evidence suggests that even minor increases of perioperative creatinine levels—not meeting Kidney Disease Improving Global Outcomes definition for acute kidney injury—are related to a doubling of perioperative mortality and longer hospital length of stay.[5] Haase et al.[18] determined that even without diagnostic fluctuations in serum creatinine, subclinical acute kidney injury is associated with adverse outcomes.

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