When is saline preferred over lactated Ringer's (LR) for fluid administration?

When to Use Saline Over Lactated Ringer's

Saline (0.9% sodium chloride) should be preferred over lactated Ringer's solution in patients with severe traumatic brain injury, hyperkalemia, or when administering blood products, particularly packed red blood cells. 1

Specific Clinical Scenarios for Saline Preference

1. Traumatic Brain Injury

• Lactated Ringer's solution is hypotonic relative to plasma and should be avoided in patients with severe head trauma 1
• Hypotonic solutions can worsen cerebral edema by promoting fluid shift into damaged cerebral tissue 1
• A secondary analysis from the PROMMTT study revealed that Ringer's lactate solutions were associated with higher adjusted mortality compared with normal saline in TBI patients 1

2. Hyperkalemia

• Lactated Ringer's contains potassium (4 mEq/L)
• In patients with hyperkalemia, saline is preferred to avoid additional potassium load
• This is particularly important in patients with renal dysfunction who cannot effectively clear potassium

3. Blood Product Administration

• Saline is preferred when administering blood products
• Calcium in lactated Ringer's can potentially bind with citrate anticoagulants in stored blood products
• This interaction may lead to clot formation in the IV line

4. Severe Metabolic Alkalosis

• Saline is preferred in patients with metabolic alkalosis
• Lactate in Ringer's solution is metabolized to bicarbonate, which can worsen alkalosis

Important Considerations When Using Saline

Volume Limitations

• If 0.9% sodium chloride solution is used, it should be limited to a maximum of 1–1.5 L 1
• Excessive saline administration can lead to:
  • Hyperchloremic metabolic acidosis
  • Increased risk of acute kidney injury
  • Electrolyte disturbances

Contraindications for Saline

• Saline solutions should not be used in severe acidosis, especially when associated with hyperchloremia 1
• In patients with hemorrhagic shock without TBI, balanced crystalloid solutions may be preferable 1

Evidence for Balanced Solutions in Other Scenarios

For most other clinical scenarios, balanced crystalloid solutions (like lactated Ringer's) may be preferable:

• The European guideline on management of major bleeding and coagulopathy recommends balanced crystalloid solutions as the initial crystalloid solution in trauma patients 1
• In emergency laparotomy, balanced crystalloids may result in improved patient outcomes with reduced morbidity and mortality compared to saline 1
• In massive hemorrhage models, lactated Ringer's has shown superior outcomes compared to normal saline (pH 7.39 vs. 7.14 and 100% vs. 50% survival) 2

Algorithm for Fluid Selection

1. Use saline (0.9% sodium chloride) if:

   • Patient has traumatic brain injury
   • Patient has hyperkalemia
   • Administering blood products
   • Patient has metabolic alkalosis

2. Use balanced crystalloids (like lactated Ringer's) if:

   • Patient has metabolic acidosis
   • Patient has hyperchloremia
   • Significant volume resuscitation is anticipated (>1.5L)
   • Patient has sepsis without contraindications to lactated Ringer's

3. Monitor for complications:

   • With saline: hyperchloremic metabolic acidosis, acute kidney injury
   • With lactated Ringer's: potential worsening of cerebral edema in TBI

By following this evidence-based approach to fluid selection, clinicians can optimize patient outcomes while minimizing potential complications associated with inappropriate fluid therapy.