Can normal saline (NS) by intravenous (IV) infusion exacerbate dehydration and electrolyte imbalances in a patient with diarrhea?

Normal Saline IV Infusion for Dehydration with Diarrhea

Normal saline (NS) IV infusion is appropriate for severe dehydration due to diarrhea, but should be transitioned to oral rehydration solution (ORS) once the patient is stabilized to prevent potential electrolyte imbalances.

Initial Assessment and Fluid Choice

Normal saline is indicated in specific circumstances for patients with diarrhea:

• Severe dehydration: When there is shock, altered mental status, or failure of oral rehydration therapy 1
• Ileus: When intestinal motility is compromised 1
• Intractable vomiting: When oral intake is impossible 1

However, NS should not be the default or prolonged treatment for all cases of dehydration with diarrhea.

Potential Issues with Prolonged NS Infusion

Prolonged use of normal saline in diarrheal illness may potentially worsen:

1. Metabolic acidosis: Balanced solutions like Ringer's lactate produce higher increases in blood pH (MD 0.06,95% CI 0.03 to 0.09) and bicarbonate levels (MD 2.44 mEq/L, 95% CI 0.92 to 3.97) compared to NS 2

2. Electrolyte imbalances: NS may increase risk of hypokalaemia compared to balanced solutions (RR 0.54,95% CI 0.31 to 0.96) 2

3. Length of hospitalization: Balanced solutions likely result in slightly shorter hospital stays compared to NS (mean difference -0.35 days, 95% CI -0.60 to -0.10) 2

Optimal Rehydration Approach

For optimal management of dehydration with diarrhea:

1. Initial resuscitation: For severe dehydration, use isotonic IV fluids (NS or Ringer's lactate) at 60-100 ml/kg in the first 2-4 hours to restore circulation 3

2. Transition to ORS: Once circulation is restored and the patient is alert:

   • Switch to reduced osmolarity ORS as the primary rehydration method 1, 4
   • Continue IV rehydration only until pulse, perfusion, and mental status normalize 1

3. Maintenance phase:

   • Replace ongoing losses with ORS until diarrhea resolves 1
   • Resume age-appropriate diet during or immediately after rehydration 1, 4

Practical Algorithm for Fluid Management

1. Assess dehydration severity:

   • Mild to moderate: Use ORS exclusively
   • Severe: Begin with IV fluids

2. For severe dehydration requiring IV fluids:

   • First 2-4 hours: NS or Ringer's lactate at 60-100 ml/kg
   • Monitor: Pulse, perfusion, mental status, urine output
   • When stabilized: Transition to ORS for remaining deficit

3. If continued IV fluids needed (due to persistent vomiting or ileus):

   • Consider balanced solutions like Ringer's lactate rather than prolonged NS
   • Add potassium (20 mEq/L) once urine output is established 3

Common Pitfalls to Avoid

• Prolonged NS use: Can potentially worsen metabolic acidosis in diarrheal illness
• Delayed transition to oral therapy: IV therapy should be used only until the patient can tolerate oral intake
• Withholding food: Resume age-appropriate diet promptly to minimize nutritional impact 1, 4
• Neglecting ongoing losses: Continue to replace stool losses with ORS even after initial rehydration 1

In conclusion, while normal saline is appropriate for initial resuscitation in severe dehydration with diarrhea, prolonged use may potentially worsen electrolyte imbalances and metabolic acidosis. The optimal approach is to transition to ORS as soon as the patient is stabilized.