Metabolic Conditioning for Renal Protection During Cardiopulmonary Bypass: A Narrative Review

Area of Science:

• Nephrology
• Cardiology
• Critical Care Medicine

Background:

• Acute kidney injury (AKI) is a frequent complication after cardiac surgery, associated with poor patient outcomes.
• Renal injury can occur despite adequate perfusion, suggesting other factors like metabolic stress are involved.
• Cardiopulmonary bypass (CPB) can induce metabolic stress and protein catabolism, increasing kidney vulnerability.

Purpose of the Study:

• To review the evidence on intravenous amino acid administration as a renal protection strategy in cardiac surgery.
• To evaluate the role of metabolic interventions in preventing cardiac surgery-associated AKI (CSA-AKI).

Main Methods:

• A narrative review of studies identified through PubMed/MEDLINE, Embase, and Cochrane Library up to March 2025.
• Included randomized controlled trials, meta-analyses, systematic reviews, and expert reviews focusing on AKI, cardiac surgery, CPB, and amino acids.
• Emphasis on high-quality evidence, including the PROTECTION trial and contemporary meta-analyses.

Main Results:

• Intravenous amino acid infusion was linked to lower rates of postoperative AKI, especially in patients with pre-existing kidney disease.
• No significant safety concerns were identified with amino acid administration.
• CSA-AKI arises from a combination of factors including altered perfusion, inflammation, ischemia-reperfusion, and CPB-induced metabolic issues.

Conclusions:

• Intravenous amino acid infusion is a promising strategy to reduce AKI following cardiac surgery.
• This metabolic approach complements goal-directed perfusion, expanding AKI prevention beyond hemodynamic management.
• Further research is needed on optimal timing, dosing, and integration into multimodal AKI prevention strategies.