How can postoperative Acute Kidney Injury (AKI) be prevented and managed in patients with Diabetes Mellitus (DM) undergoing surgery?

Prevention and Management of Postoperative Acute Kidney Injury in Diabetic Patients

Diabetic patients undergoing surgery should maintain strict glycemic control with target blood glucose levels less than 180 mg/dL to prevent postoperative acute kidney injury (AKI) while avoiding hypoglycemia. 1

Preoperative Assessment and Risk Stratification

• Evaluate renal function preoperatively using estimated glomerular filtration rate (eGFR) and albumin-to-creatinine ratio (ACR) in all diabetic patients scheduled for surgery 1
• Identify patients at high risk for AKI using urinary biomarkers (such as tissue inhibitor of metalloproteinases-2 and insulin-like growth factor-binding protein 7) which can detect kidney stress as early as 1 hour after cardiopulmonary bypass 1
• Postpone elective surgery if glycemic control is poor (HbA1c >8% or blood glucose >16.5 mmol/L) and refer to a diabetologist for improved control 2
• Assess for diabetic chronic kidney disease (DCKD), which significantly increases the risk of postoperative AKI 1

Perioperative Medication Management

• Temporarily discontinue metformin at the time of surgery due to the risk of lactic acidosis, especially in patients with compromised renal function 3
• Stop metformin prior to procedures involving iodinated contrast in patients with eGFR between 30-60 mL/min/1.73m² 3
• Discontinue angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) for 48 hours in patients at risk of AKI 1
• Avoid nephrotoxic medications in the perioperative period 1

Intraoperative Management

• Implement goal-directed fluid therapy using standardized algorithms to guide administration of fluids, vasopressors, and inotropes to avoid hypotension and low cardiac output 1
• Maintain mean arterial pressure between 60-70 mmHg, or >70 mmHg in hypertensive patients, to ensure adequate renal perfusion 1
• Monitor blood glucose levels hourly during surgery and initiate insulin therapy for glucose levels ≥180 mg/dL 1, 4
• Use continuous intravenous insulin infusion with decreasing target glucose concentrations for optimal glycemic control during cardiac surgery 1
• Consider haemodynamic monitoring to evaluate stroke volume and guide vascular filling during procedures with risk of haemodynamic instability 1

Postoperative Management

• Continue strict glycemic control postoperatively with target blood glucose <180 mg/dL 1, 5
• Implement early detection strategies for AKI using urinary biomarkers and implement intervention protocols for at-risk patients 1
• Avoid nephrotoxic agents, maintain close monitoring of creatinine and urine output, and optimize volume status and hemodynamic parameters in patients identified as high-risk for AKI 1
• Resume oral feeding as soon as possible after surgery to minimize insulin resistance 2, 6
• Monitor for and treat hypoglycemia promptly, especially in patients who may have hypoglycemia unawareness 7

Special Considerations for Diabetic Patients

• Diabetes is an independent risk factor for postoperative AKI, which can develop even in patients without previous renal dysfunction 1, 8
• Diabetic patients with AKI have higher risk of progression to chronic kidney disease and end-stage renal disease 9, 8
• Poor intraoperative glycemic control is associated with increased postoperative morbidity, particularly in cardiac surgery 4
• Stress hyperglycemia in the perioperative period is caused by insulin resistance due to surgical stress hormones and inflammatory mediators 6, 10

Common Pitfalls and How to Avoid Them

• Failing to identify patients at risk for AKI preoperatively - use risk stratification tools and biomarkers 1
• Inadequate glycemic control during surgery - implement protocols for hourly glucose monitoring and insulin therapy 1, 4
• Assuming postoperative drowsiness is solely due to anesthesia rather than possible hypoglycemia - monitor blood glucose regularly 7
• Neglecting to adjust fluid management based on renal function - use goal-directed fluid therapy 1
• Restarting nephrotoxic medications too early - wait until renal function is stable 1, 3

By implementing these evidence-based strategies, the risk of postoperative AKI in diabetic patients can be significantly reduced, leading to improved outcomes and reduced morbidity and mortality.