What is the preferred fluid management option for a patient with impaired renal function, comparing balanced crystalloid solutions (such as lactated Ringer's solution or Plasma-Lyte) to sorbitol + amino acids?

Balanced Crystalloids Are Strongly Preferred Over Sorbitol + Amino Acids for Renal Patients

For patients with impaired renal function, balanced crystalloid solutions (lactated Ringer's or Plasma-Lyte) should be used as first-line fluid therapy rather than sorbitol + amino acids, as balanced crystalloids reduce major adverse kidney events and mortality in critically ill patients. 1, 2

Primary Evidence Supporting Balanced Crystalloids

The SMART trial, which enrolled 15,802 critically ill adults including those with renal dysfunction, demonstrated that balanced crystalloids resulted in significantly lower rates of major adverse kidney events (14.3% vs 15.4%, OR 0.91,95% CI 0.84-0.99, P=0.04) compared to normal saline. 2 This composite outcome included death, new renal replacement therapy, or persistent renal dysfunction. 2

Balanced crystalloids are specifically recommended by the European Society of Anaesthesiology as first-line fluid therapy to reduce mortality and adverse renal events in patients at risk for acute kidney injury. 3, 1

Why Balanced Crystalloids Protect Renal Function

• Balanced crystalloids have electrolyte compositions closer to plasma (sodium 130 mmol/L, chloride 108-109 mmol/L) compared to normal saline's supraphysiologic chloride concentration (154 mmol/L), which prevents hyperchloremic metabolic acidosis. 1, 4

• Hyperchloremic acidosis from high-chloride fluids causes renal vasoconstriction and acute kidney injury, with increased 30-day mortality when hyperchloremia develops. 1

• Large volumes of chloride-rich solutions (>5000 mL) have been associated with increased mortality in observational studies. 1

Specific Recommendations for Renal Patients

The KDIGO guidelines recommend isotonic crystalloids rather than colloids for expansion of intravascular volume in patients at risk for acute kidney injury. 5 Balanced crystalloids like lactated Ringer's are appropriate and recommended for patients with acute kidney injury, with critical exceptions noted below. 6

• The potassium content in lactated Ringer's (4 mmol/L) should not be considered a contraindication in patients with mild-to-moderate hyperkalemia or renal dysfunction, except in rhabdomyolysis/crush syndrome. 6

• In renal transplant recipients, a population at high risk for hyperkalemia, patients receiving 0.9% NaCl actually developed higher potassium levels than those receiving Ringer's lactate. 6

Critical Contraindications to Consider

Avoid lactated Ringer's in patients with severe traumatic brain injury or head trauma due to its hypotonic nature (osmolarity 273-277 mOsm/L), which can worsen cerebral edema. 6 In these specific cases, 0.9% saline is the recommended isotonic crystalloid of choice. 6

• Avoid balanced crystalloids in suspected or proven rhabdomyolysis or crush syndrome due to potassium content. 6

Why Colloids Should Be Avoided

Synthetic colloids (hydroxyethyl starch, gelatin) should be avoided in renal patients due to reported risks of renal failure and lack of mortality benefit. 3, 1 The FLASH study showed renal failure was significantly more frequent in the hydroxyethyl starch group (RR 1.34,95% CI 1.0-1.8, P=0.05). 3

Practical Algorithm for Fluid Selection in Renal Patients

1. Assess for contraindications: Check for severe TBI, rhabdomyolysis, or crush syndrome. 6

2. If no contraindications present: Use balanced crystalloids (lactated Ringer's or Plasma-Lyte) as first-line therapy. 1, 2

3. Monitor: Track urine output, vital signs, electrolytes, and renal function. 5

4. Avoid: Do not use synthetic colloids, large volumes of normal saline, or sorbitol + amino acid solutions. 3, 1

Common Pitfalls to Avoid

• Do not assume that potassium in balanced crystalloids is dangerous for renal patients—physiologically, it is not possible to create potassium excess using a fluid with potassium concentration equal to or lower than plasma concentration. 6

• Do not use large volume 0.9% saline based on outdated protocols from before 2018, as this is associated with increased mortality and major adverse kidney events. 1

• Do not use albumin for fluid resuscitation in renal patients, as studies show no benefit and it is more expensive than crystalloid solutions. 3