From the Guidelines
0.9% sodium chloride (normal saline) is preferred over lactated Ringer's solution in patients with severe head trauma, as it has a slightly higher osmolarity that may help reduce intracranial pressure, and in patients where hypotonic solutions should be avoided 1.
Key Considerations
- Normal saline is the fluid of choice for patients with metabolic alkalosis, severe hyponatremia, or hyperkalemia since it contains no potassium and can help correct sodium deficits.
- It's also preferred in patients with traumatic brain injury or at risk for cerebral edema because it has a slightly higher osmolarity that may help reduce intracranial pressure.
- Normal saline is the recommended fluid for diluting blood products for transfusion, as calcium in lactated Ringer's can promote clotting in transfusion lines.
- Additionally, it's preferred in patients taking lithium or certain medications that are affected by calcium, and in those with severe liver disease who may have difficulty metabolizing lactate.
Clinical Context
- The higher chloride content in normal saline creates a mild acidifying effect, which can be beneficial in alkalotic states but should be used cautiously in patients with kidney disease or those at risk for hyperchloremic metabolic acidosis with prolonged administration.
- Recent guidelines suggest that balanced crystalloids may be advantageous over 0.9% sodium chloride in certain situations, but the evidence is not yet conclusive 1.
- A large RCT including 15,802 critically ill patients comparing balanced crystalloids versus 0.9% sodium chloride showed a lower rate of the composite outcome “death from any cause, new renal-replacement therapy or persistent renal dysfunction” when balanced crystalloids were used 1.
Recommendations
- Use 0.9% sodium chloride (normal saline) in patients with severe head trauma or where hypotonic solutions should be avoided 1.
- Consider using balanced crystalloids in other situations, but be aware of the potential risks and benefits.
- Always consider the individual patient's needs and clinical context when choosing a fluid for resuscitation.
From the FDA Drug Label
INDICATIONS AND USAGE: ... Isotonic Sodium Chloride Injection should be limited to cases in which the chloride loss is greater than the sodium loss, as in vomiting from pyloric obstruction, or in which the loss is about equal, as in vomiting from duodenal, jejunal or ileal obstruction and in the replacement of aspirated gastrointestinal fluids
- 0.9% sodium chloride (normal saline) is preferred over lactated Ringer's (LR) solution in cases where:
- Chloride loss is greater than sodium loss, such as vomiting from pyloric obstruction
- Chloride loss is about equal to sodium loss, such as vomiting from duodenal, jejunal or ileal obstruction
- Replacement of aspirated gastrointestinal fluids is needed 2
From the Research
Preferred Use of 0.9% Sodium Chloride
0.9% sodium chloride (normal saline) is preferred over lactated Ringer's (LR) solution in certain situations:
- In patients with severe metabolic alkalosis, as lactated Ringer's can exacerbate the condition 3
- In patients with lactic acidosis with decreased lactate clearance, as lactated Ringer's contains lactate 3
- In patients with severe hyperkalemia, as lactated Ringer's contains potassium 3
- In patients with traumatic brain injury or at risk of increased intracranial pressure, as the optimal fluid choice in these situations is still debated and may depend on individual patient factors 3
- During renal transplantation, normal saline is often used to avoid the risk of hyperkalemia associated with potassium-containing fluids, although some studies suggest that lactated Ringer's may be a safe alternative 4
Key Considerations
When choosing between normal saline and lactated Ringer's, clinicians should consider the following factors:
- The cause of hypovolemia
- The cardiovascular state of the patient
- Renal function
- Serum osmolality
- Coexisting acid-base and electrolyte disorders 3
- The potential risks and benefits of each fluid, including the risk of hyperchloremic metabolic acidosis and renal vasoconstriction associated with normal saline 3