Evaluation of Renal Function
A comprehensive preoperative evaluation of kidney function is essential in patients with AKI. This includes reviewing baseline serum creatinine, blood urea nitrogen (BUN), urine output, and recent trends in renal function. Special attention should be given to any recent changes in renal function, electrolyte imbalances (e.g., hyperkalemia, acidosis), and volume status. In AKI, even small deviations in serum creatinine can signal significant changes in renal function, so careful monitoring and comparison to baseline values are crucial.
Risk Stratification
It is essential to stratify the risk of AKI worsening during surgery based on the patient's comorbidities, type of surgery, and any prior kidney insults. Surgical procedures such as cardiac, vascular, and major abdominal surgeries carry a higher risk of perioperative AKI due to ischemia-reperfusion injuries, extensive fluid shifts, and potential hypotension. Pre-existing chronic kidney disease (CKD), diabetes, hypertension, and heart failure are also important risk factors.
Medications Review
The anesthesia provider must review the patient's medications to identify any nephrotoxic agents (e.g., NSAIDs, certain antibiotics, ACE inhibitors, or angiotensin receptor blockers [ARBs]) and discontinue or modify them as needed. ACE inhibitors and ARBs, for example, can exacerbate AKI by impairing renal autoregulation, particularly during episodes of hypotension. If these agents are continued preoperatively, careful intraoperative blood pressure monitoring and management are required.
Volume Status and Optimization
Assessing and optimizing the patient's volume status preoperatively is critical. AKI patients often have volume imbalances, which can complicate anesthesia management. In hypovolemic patients, cautious fluid resuscitation with balanced crystalloids (e.g., lactated Ringer's solution or Plasma-Lyte) can help restore renal perfusion. However, volume overload, which is common in oliguric AKI, may necessitate diuresis or ultrafiltration before surgery to avoid complications such as pulmonary edema or heart failure.
