Should a history of Acute Kidney Injury (AKI) due to amphotericin B be considered before performing litholapaxy?

Prior Amphotericin B-Induced AKI and Litholapaxy: Risk Assessment

Yes, a history of amphotericin B-induced AKI must be carefully considered before performing litholapaxy, as prior nephrotoxic injury significantly increases vulnerability to subsequent renal insults during any procedure requiring contrast, hemodynamic stress, or additional nephrotoxic exposures.

Why Prior Amphotericin B AKI Matters

Established Vulnerability to Re-injury

• Patients who have experienced AKI from any cause, including drug-induced nephrotoxicity, remain at heightened risk for recurrent kidney injury during the recovery and post-recovery phases 1.
• The ADQI consensus emphasizes that during the acute kidney disease (AKD) period following AKI, caution must be applied to any intervention that could cause re-injury, as this vulnerable period extends well beyond the acute phase 1.
• Each additional nephrotoxin exposure increases AKI odds by 53%, and combining multiple nephrotoxic insults more than doubles the risk 1.

Amphotericin B Creates Lasting Renal Vulnerability

• Amphotericin B causes direct tubular damage and renal vasoconstriction, with some permanent impairment often occurring, especially in patients receiving large cumulative doses (>5g) or other nephrotoxic agents 2, 3.
• Even with liposomal formulations, 19-50% of patients develop some degree of renal injury, and the FDA label explicitly warns that permanent renal impairment frequently occurs 2, 3.
• Prior treatment with ACE inhibitors/ARBs or carbapenems during amphotericin therapy is associated with higher subsequent AKI rates 4.

Pre-Litholapaxy Risk Assessment Algorithm

Step 1: Evaluate Current Renal Function

• Assess current serum creatinine and compare to pre-amphotericin baseline values to determine degree of recovery 1.
• Complete renal recovery (creatinine within 10% of baseline) occurs in only approximately one-third of patients after amphotericin-induced AKI, with mean recovery time of 9.8 days when it does occur 5.
• If creatinine remains elevated above baseline, the patient is in the persistent AKD phase and at maximum vulnerability 1.

Step 2: Identify Litholapaxy-Specific Risk Factors

• Screen for pre-existing renal impairment and assess cumulative nephrotoxic burden, as litholapaxy may involve contrast exposure, irrigation fluid absorption, and hemodynamic stress 1.
• The KDIGO guidelines mandate screening for pre-existing kidney impairment before any procedure requiring contrast administration 1.

Step 3: Implement Mandatory Protective Strategies

If litholapaxy must proceed despite prior amphotericin AKI:

• Use the lowest possible contrast dose or consider contrast-free imaging alternatives when feasible 1.
• Administer IV volume expansion with isotonic sodium chloride or sodium bicarbonate rather than oral fluids alone 1.
• Consider oral N-acetylcysteine together with IV isotonic crystalloids (Grade 2D recommendation for contrast procedures) 1.
• Discontinue all non-essential nephrotoxic medications including NSAIDs, diuretics, and aminoglycosides 1, 2.

Step 4: Optimize Hemodynamic Status

• Ensure adequate volume repletion and avoid hypotension during the procedure, as hemodynamic instability compounds nephrotoxic risk 1.
• Target mean arterial pressure >65 mmHg if hemodynamic support is required 1.

Critical Caveats and Pitfalls

The "Triple Whammy" Risk

• Avoid combining NSAIDs, diuretics, and ACE inhibitors/ARBs in the perioperative period, as this pharmacodynamic interaction dramatically increases AKI risk 1.
• This is particularly relevant given that prior ACE inhibitor/ARB use during amphotericin therapy predicts higher subsequent AKI rates 4.

Timing Considerations

• If possible, delay elective litholapaxy until complete renal recovery is documented (creatinine within 10% of pre-amphotericin baseline) 5.
• The vulnerable AKD period extends beyond normalization of creatinine, so even "recovered" patients require enhanced monitoring 1.

Monitoring Requirements

• Monitor serum creatinine and electrolytes (particularly potassium and magnesium) closely in the perioperative period, as amphotericin-induced electrolyte derangements may persist 2, 3.
• Hypokalemia before any subsequent procedure requiring nephrotoxic exposure is associated with more severe AKI 4.

When to Reconsider the Procedure

Litholapaxy should be deferred or alternative management considered if:

• Serum creatinine remains >1.5× baseline from amphotericin-induced AKI 1.
• Multiple concomitant nephrotoxins cannot be discontinued 1.
• Hemodynamic instability or volume depletion cannot be corrected pre-procedure 1.
• The patient requires ongoing vasopressor support or immunosuppression, both of which compound AKI risk 4.

The fundamental principle is that prior amphotericin B-induced AKI represents established renal vulnerability that mandates aggressive preventive strategies and careful risk-benefit analysis before any procedure with nephrotoxic potential 1, 2.