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Acute Kidney Injury (AKI)

Content Type: Protocols | Provider

Created: September 30, 2023
Contributor(s): Daniel Engelman MD • Alexander Zarbock MD • ERAS Cardiac Collaborative Network
Editor(s): Daniel Engelman MD • Alexander Zarbock MD • Cheryl Crisafi MSN RN CNL • Amanda Rea DNP CRNP AGACNP-BC CCRN CMC CSC E-AEC • Gina McConnell RN BSN CCRN • Shannon Crotwell RN BSN CCRN • Alexander Gregory MD FRCPC

Summary

Acute kidney injury after cardiac surgery is common and clinically significant. Even transient stage 1 AKI is associated with increased long term mortality. Early identification of patients at risk, detection of kidney stress before overt injury, and timely initiation of kidney protection strategies are essential components of an ERAS Cardiac program.

Traditional markers such as serum creatinine and urine output identify kidney injury late in the course of illness. Urinary stress biomarkers, including tissue inhibitor of metalloproteinases 2 (TIMP 2) and insulin like growth factor binding protein 7 (IGFBP7), can detect kidneys under stress before structural damage occurs. Integrating these tools into a structured AKI prevention bundle supports earlier intervention, more consistent care, and improved outcomes.

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Key Concepts in AKI Prevention after Cardiac Surgery

  • Even mild, transient stage 1 AKI is associated with increased morbidity and long term mortality after cardiac surgery.
  • AKI contributes to prolonged ICU and hospital length of stay, higher readmission rates, and increased healthcare costs.
  • Prevention and early recognition of kidney injury are central goals within ERAS Cardiac pathways.

  • Serum creatinine is a delayed marker of kidney dysfunction and may not rise until approximately 50 percent of the glomerular filtration rate has been lost.
  • Urine output is influenced by multiple factors, including volume status, hemodynamics, medications, and diuretic use, so it has low specificity for structural kidney injury.
  • Relying solely on creatinine and urine output can result in missed opportunities for early intervention.

  • Urinary TIMP 2 and IGFBP7 identify kidneys under stress prior to the development of overt AKI.
  • These biomarkers are more sensitive than creatinine or urine output for recognizing patients at high risk of AKI in the early postoperative period.
  • Biomarker guided protocols allow clinicians to escalate monitoring and implement kidney protective strategies before injury progresses.

  • The Kidney Disease Improving Global Outcomes (KDIGO) Guidelines are the primary international reference for the classification, diagnosis, management, and prevention of AKI.
  • Published in 2012, KDIGO provides graded recommendations for AKI risk assessment and kidney protection strategies in patients with kidneys under stress.
  • ERAS Cardiac pathways can align local protocols with KDIGO staging criteria and AKI risk interventions.
  • Teams are encouraged to review the full KDIGO guideline document for detailed recommendations.

  • Many cardiac surgery patients meet criteria for high risk of AKI based on age, comorbidities, surgical complexity, and perioperative hemodynamics.
  • In some programs, all patients undergoing cardiac surgery are considered at risk and are monitored using standardized AKI screening protocols.
  • Preoperative and intraoperative risk assessment tools can help stratify patients and guide the intensity of monitoring and prevention strategies.

  • Urinary biomarker results can trigger initiation or escalation of an AKI prevention bundle.
  • Core components of kidney protection bundles typically include:
    • Minimizing additional nephrotoxic exposures, such as certain medications and contrast agents.
    • Optimizing hemodynamics and perfusion through goal directed therapy.
    • Maintaining appropriate intravascular volume and avoiding both hypovolemia and fluid overload.
    • Adjusting drug dosing based on kidney function and patient specific factors.
    • Enhancing monitoring in higher risk patients, including more frequent labs and clinical assessments.
  • Bundles should be standardized, algorithm driven, and embedded into routine workflows within the ICU and ward settings.

  • AKI prevention requires tight collaboration among surgeons, anesthesiologists, intensivists, nephrologists, perfusionists, nurses, and pharmacists.
  • Teams should establish clear communication pathways for biomarker results and AKI alerts.
  • Regular multidisciplinary reviews of AKI cases can identify improvement opportunities and strengthen protocol adherence.

  • Studies in both cardiac and non cardiac surgery populations have shown that biomarker guided AKI prevention strategies can reduce the incidence and severity of AKI.
  • Protocols vary across institutions but share common features, including early biomarker measurement, standardized bundle activation, and team based care.
  • Programs should monitor local AKI rates, adoption of prevention bundles, and patient outcomes to evaluate impact and refine pathways over time.

AI Assistance Statement

This summary was developed with assistance from artificial intelligence and reviewed, edited, and approved by the listed editor(s). Reference: OpenAI (2025). ChatGPT (November version) [Large language model]. 
https://chat.openai.com

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All healthcare professionals should continue to exercise sound clinical judgment and base therapeutic decisions on the best available evidence and patient specific factors.

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References

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