KDIGO Clinical Practice Guideline for Acute Kidney Injury
Recommendations and Rationale

• 2.3.1: Evaluate patients with AKI promptly to determine the cause, with special attention to reversible causes.(Not Graded):
• 2.3.2: Monitor patients with AKI with measurements of SCr and urine output to stage the severity, according to Recommendation 2.1.2.(Not Graded):
• 2.3.3: Manage patients with AKI according to the stage (see Figure 4) and cause.(Not Graded):
• 2.3.4: Evaluate patients 3 months after AKI for resolution, new onset, or worsening of pre-existing CKD.(Not Graded):
  • If patients have CKD, manage these patients as detailed in the KDOQI CKD Guideline (Guidelines 7–15). (Not Graded)
  • If patients do not have CKD, consider them to be at increased risk for CKD and care for them as detailed in the KDOQI CKD Guideline 3 for patients at increased risk for CKD. (Not Graded)

Figure 4 | Stage-based management of AKI. Shading of boxes indicates priority of action—solid shading indicates actions that are equally appropriate at all stages whereas graded shading indicates increasing priority as intensity increases. AKI, acute kidney injury; ICU, intensive-care unit.

Rationale

As emphasized in Chapter 2.2, AKI is not a disease but rather a clinical syndrome with multiple etiologies. While much of the literature examining epidemiology and clinical consequences of AKI appear to treat this syndrome as a homogeneous disorder, the reality is that AKI is heterogeneous and often is the result of multiple insults. Figure 5 illustrates an approach to evaluation of AKI. Further discussion of evaluation in clinical practice is provided in Appendix D.

The clinical evaluation of AKI includes a careful history and physical examination. Drug history should include overthe- counter formulations and herbal remedies or recreational drugs. The social history should include exposure to tropical diseases (e.g., malaria), waterways or sewage systems, and exposure to rodents (e.g., leptospirosis, hantavirus). Physical examination should include evaluation of fluid status, signs for acute and chronic heart failure, infection, and sepsis.

Measurement of cardiac output, preload, preload responsiveness, and intra-abdominal pressure should be considered

Figure 5 | Evaluation of AKI according to the stage and cause.

in the appropriate clinical context. Laboratory parameters— including SCr, blood urea nitrogen (BUN), and electrolytes, complete blood count and differential—should be obtained. Urine analysis and microscopic examination as well as urinary chemistries may be helpful in determining the underlying cause of AKI. Imaging tests, especially ultrasound, are important components of the evaluation for patients with AKI. Finally, a number of biomarkers of functional change and cellular damage are under evaluation for early diagnosis, risk assessment for, and prognosis of AKI (see Appendix D for detailed discussion).

Individualize frequency and duration of monitoring based on patient risk, exposure and clinical course. Stage is a predictor of the risk for mortality and decreased kidney function (see Chapter 2.4). Dependent on the stage, the intensity of future preventive measures and therapy should be performed.

Because the stage of AKI has clearly been shown to correlate with short-term^2,5,27,29 and even longer-term outcomes,³¹ it is advisable to tailor management to AKI stage. Figure 4 lists a set of actions that should be considered for patients with AKI. Note that for patients at increased risk (see Chapters 2.2 and 2.4), these actions actually begin even before AKI is diagnosed.

Note that management and diagnostic steps are both included in Figure 4. This is because response to therapy is an important part of the diagnostic approach. There are few specific tests to establish the etiology of AKI. However, a patient’s response to treatment (e.g., discontinuation of a possible nephrotoxic agent) provides important information as to the diagnosis.

Nephrotoxic drugs account for some part of AKI in 20–30% of patients. Often, agents like antimicrobials (e.g., aminoglycosides, amphotericin) and radiocontrast are used in patients that are already at high risk for AKI (e.g., critically ill patients with sepsis). Thus, it is often difficult to discern exactly what contribution these agents have on the overall course of AKI. Nevertheless, it seems prudent to limit exposure to these agents whenever possible and to weigh the risk of developing or worsening AKI against the risk associated with not using the agent. For example, when alternative therapies or diagnostic approaches are available they should be considered.

In order to ensure adequate circulating blood volume, it is sometimes necessary to obtain hemodynamic variables. Static variables like central venous pressure are not nearly as useful as dynamic variables, such as pulse-pressure variation, inferior vena cava filling by ultrasound and echocardiographic appearance of the heart (see also Appendix D).

Note that while the actions listed in Figure 4 provide an overall starting point for stage-based evaluation and management, they are neither complete not mandatory for an individual patient. For example, the measurement of urine output does not imply that the urinary bladder catheterization is mandatory for all patients, and clinicians should balance the risks of any procedures with the benefits. Furthermore, clinicians must individualize care decisions based on the totality of the clinical situation. However, it is advisable to include AKI stage in these decisions.

The evaluation and management of patients with AKI requires attention to cause and stage of AKI, as well as factors that relate to further injury to the kidney, or complications from decreased kidney function. Since AKI is a risk factor for CKD, it is important to evaluate patients with AKI for new onset or worsening of pre-existing CKD. If patients have CKD, manage patients as detailed in the KDOQI CKD Guideline (Guidelines 7–15). If patients do not have CKD, consider them to be at increased risk for CKD and care for them as detailed in the KDOQI CKD Guideline 3 for patients at increased risk for CKD.