Is it safe to keep a patient on normal saline (0.9% sodium chloride) infusion at 45 cc/hour for more than 3 days?

Safety of Prolonged Normal Saline Infusion at 45 cc/hour

Prolonged infusion of normal saline at 45 cc/hour (approximately 1080 cc/day) for more than three days is not recommended due to the risk of hyperchloremic metabolic acidosis, renal vasoconstriction, and acute kidney injury, especially in vulnerable patients.

Risks of Prolonged Normal Saline Infusion

Electrolyte and Acid-Base Disturbances

• Administration of large volumes of 0.9% saline can cause hyperchloremic acidosis, renal vasoconstriction, and acute kidney injury (AKI) 1
• Hyperchloremia has been associated with increased 30-day mortality in approximately 20% of patients undergoing noncardiac surgery 1
• The FDA label for sodium chloride IV warns that parenteral administration of sodium in excess of needed amounts may result in edema and clinical findings resembling congestive heart failure 2

Kidney Function Impact

• The SALT trial showed that patients receiving large volumes of 0.9% saline had a higher rate of major adverse kidney events compared to those receiving buffered fluids 1
• A large trial with 15,802 critically ill patients demonstrated that buffered crystalloids were associated with a lower risk of major adverse kidney events than 0.9% saline 1

Volume and Duration Considerations

Daily Fluid Load

• At 45 cc/hour, the patient would receive approximately 1080 cc/day of normal saline
• While this is not considered a large volume for acute resuscitation, the cumulative effect over more than 3 days may lead to:
  • Sodium and chloride accumulation
  • Potential fluid overload in susceptible patients
  • Progressive development of hyperchloremic metabolic acidosis

Patient-Specific Risk Factors

• Higher risk in patients with:
  • Pre-existing renal dysfunction
  • Cardiac impairment
  • Electrolyte disturbances
  • Acidosis
  • Advanced age

Recommended Alternatives

Preferred Fluid Choice

• Buffered crystalloid solutions are recommended over 0.9% saline for maintenance fluid therapy 1
• If fluid therapy is needed beyond 3 days, consider switching to a balanced electrolyte solution to minimize the risk of hyperchloremic acidosis 1

Monitoring Requirements

If normal saline infusion must be continued beyond 3 days:

• Monitor serum electrolytes daily
• Check acid-base status regularly
• Assess renal function parameters
• Track fluid balance and body weight changes
• Watch for signs of fluid overload (edema, respiratory difficulty)

Special Considerations

High-Risk Scenarios

• In patients with kidney transplantation, buffered crystalloid solutions are strongly recommended over 0.9% saline (Strong recommendation, high-quality evidence) 1
• Patients with diabetic ketoacidosis may benefit from balanced fluids rather than normal saline, with evidence showing faster resolution of DKA with balanced fluids 3

Conclusion

While short-term use of normal saline at 45 cc/hour may be acceptable in many patients, extending this beyond 3 days carries increasing risks of electrolyte abnormalities and acid-base disturbances. For prolonged maintenance fluid therapy, balanced crystalloid solutions are preferred to minimize these risks.