What is the most common cause of pre-renal acute kidney injury (AKI) in the Intensive Care Unit (ICU)?

From the Guidelines

Hypovolemia is the most common cause of pre-renal acute kidney injury (AKI) in the Intensive Care Unit (ICU), often resulting from conditions such as hemorrhage, severe dehydration, or third-spacing of fluids in conditions like sepsis, as supported by the high incidence of AKI in critically ill patients 1.

Causes of Pre-renal AKI

The causes of pre-renal AKI can be multifactorial but generally include impaired blood flow from any cause, such as:

• Hypotension
• Hypovolemia
• Decreased cardiac output
• Renal artery occlusion

Clinical Context

In the ICU setting, sepsis is a significant cause of pre-renal AKI, leading to systemic vasodilation and capillary leak, which reduces renal perfusion despite normal or even elevated cardiac output 1. Other important causes include cardiogenic shock from heart failure or myocardial infarction, reducing cardiac output and renal blood flow.

Management

Management of pre-renal AKI focuses on treating the underlying cause, optimizing volume status with crystalloid or colloid solutions, discontinuing nephrotoxic medications, and supporting hemodynamics with vasopressors like norepinephrine if fluid resuscitation alone is insufficient to maintain adequate renal perfusion pressure. The identification of the specific cause of AKI is critical for appropriate intervention, as there are different treatments for various diseases 1.

From the Research

Causes of Pre-Renal Acute Kidney Injury (AKI)

• The most common causes of pre-renal AKI in the Intensive Care Unit (ICU) include:
  • Volume depletion 2, 3
  • Haemodynamic instability 2
  • Hypovolaemic shock 4, 3
  • Sepsis 4, 3
• These conditions can lead to a decrease in renal perfusion, resulting in AKI 2, 3

Risk Factors for AKI

• Other risk factors for AKI in the ICU setting include:
  • Inflammation 2
  • Nephrotoxic exposure 2, 5
  • Mitochondrial dysfunction 2
  • Advanced age 2, 4
  • Pre-existing chronic comorbidities 2

Management of AKI

• Management of AKI involves treating the underlying cause, as well as supportive care with fluid management, vasopressor therapy, and kidney replacement therapy (KRT) 5, 6
• Fluid management is crucial in preventing and managing AKI, but excessive fluid administration can be harmful 2, 3