Adjusting Fluid Rate in Patients with Lactic Acidosis and Acute Kidney Injury

Initial Fluid Management

• The British Journal of Anaesthesia recommends using buffered crystalloid solutions like Plasmalyte at an initial rate of 75-100 mL/h (approximately 1-1.5 mL/kg/h) in patients with lactic acidosis and AKI, guided by repeated hemodynamic assessment, with the goal of achieving euvolemia while avoiding fluid overload 1
• Buffered crystalloid solutions (including Plasmalyte) are strongly recommended over 0.9% saline in AKI patients because large volumes of saline cause hyperchloremic acidosis, renal vasoconstriction, and worsen kidney injury 1

Choice of Fluid

• The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines specifically recommend bicarbonate-buffered solutions over lactate-buffered solutions for renal replacement therapy (RRT) in patients with AKI and lactic acidemia 2, 3
• Plasmalyte contains acetate and gluconate (not lactate) as buffers, making it appropriate for this clinical scenario 1

Fluid Rate Adjustment

• In hemodynamically unstable patients with lactic acidosis, earlier vasopressor use may be more appropriate than aggressive fluid loading 4
• If hypovolemic with ongoing hypoperfusion, increase the fluid rate to achieve hemodynamic stability, but reassess frequently 4, 5

Renal Replacement Therapy

• The Kidney International recommends using bicarbonate-buffered dialysate/replacement fluid rather than lactate-buffered solutions in patients with lactic acidosis 2, 3
• Target effluent volume of 20-25 mL/kg/h for continuous renal replacement therapy (CRRT) 2, 3
• CRRT is preferred over intermittent hemodialysis in hemodynamically unstable patients 3

Monitoring and Avoiding Pitfalls

• The Kidney International recommends using dynamic indices (passive leg-raising test, pulse pressure variation, stroke volume variation) rather than static pressures (CVP) to assess fluid responsiveness 4
• Avoid using 0.9% saline instead of buffered crystalloids, as it worsens acidosis and kidney injury 1

IV Hydration in Acute Kidney Injury with Nephrostomy Tube

Rationale for IV Hydration

• Ensuring adequate hydration is essential in both preventing and treating Acute Kidney Injury (AKI), and maintaining adequate renal perfusion is critical for recovery in patients with obstructive uropathy requiring a nephrostomy tube 6

Key Principles of Fluid Management in AKI

• IV fluid administration should be guided by hemodynamic assessment with consideration for specific indications and contraindications 6
• Isotonic crystalloids (0.9% normal saline or balanced crystalloids) are the preferred initial fluids for volume expansion in patients with AKI 6

Specific Fluid Strategy

• Target a fluid rate of approximately 1.5 ml/kg/h of isotonic crystalloid to maintain adequate renal perfusion and urinary flow, which helps maintain urinary flow rates that reduce tubular toxicity and prevents dehydration that can worsen AKI 7, 8

Critical Assessment and Monitoring

• Before initiating fluids, assess for contraindications such as volume overload status, cardiac function, and current hemodynamic status 6, 9
• Monitor during fluid therapy, including urine output via nephrostomy tube (target >0.5 ml/kg/h), hemodynamic parameters, and signs of fluid overload 6, 7, 8

Specific Recommendations

• Initiate IV isotonic crystalloid at 75-100 ml/h (approximately 1-1.5 ml/kg/h for an average adult) using 0.9% normal saline or balanced crystalloid solution, and avoid potassium-containing solutions until the current potassium level is confirmed to be normal 6, 7, 8, 9
• Reassess fluid status every 6-12 hours, monitoring nephrostomy tube output, signs of fluid overload, and adjusting the fluid rate based on clinical response 6, 7, 9

Best IV Fluid for Dehydration with AKI

Fluid Type Selection

• The KDIGO guidelines recommend isotonic crystalloids rather than colloids as initial management for expansion of intravascular volume in patients at risk for AKI or with AKI, with a preference for buffered/balanced crystalloid solutions such as Plasmalyte or Ringer's lactate over 0.9% normal saline 10
• Do not use starch-containing colloid solutions—they are associated with harm in patients at risk of AKI or with established AKI 10
• Avoid albumin in patients with traumatic brain injury, as it is associated with harm in this specific population 10

Common Pitfalls to Avoid

• Do not use diuretics to prevent or treat AKI, except for management of volume overload, as recommended by the KDIGO guidelines 10
• Do not use low-dose dopamine, fenoldopam, or atrial natriuretic peptide—they have no benefit in preventing or treating AKI 10