What is the recommended IV treatment for a patient presenting with severe diarrhea?

IV Treatment for Severe Diarrhea

For severe dehydration (≥10% fluid deficit, shock, or near shock), immediately administer IV boluses of 20 mL/kg of Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize. 1

Initial Assessment and Severity Classification

Assess degree of dehydration clinically to determine if IV therapy is necessary: 2

• Mild dehydration (3-5% deficit): Use oral rehydration solution (ORS) only 1, 2
• Moderate dehydration (6-9% deficit): Attempt ORS first; reserve IV for ORS failure 1, 2
• Severe dehydration (≥10% deficit): This is a medical emergency requiring immediate IV access 1

Severe dehydration indicators include altered mental status, shock, poor perfusion, inability to tolerate oral intake, sunken eyes, and decreased skin turgor. 2

IV Fluid Selection and Administration

Primary IV fluid choice: Ringer's lactate or normal saline (0.9% saline) are both acceptable first-line options. 1

Balanced crystalloid solutions (Ringer's lactate) likely result in slightly shorter hospital stays (0.35 days reduction) and probably reduce the risk of hypokalaemia compared to normal saline. 3

Initial resuscitation protocol: 1

• Administer 20 mL/kg boluses rapidly
• Repeat boluses until vital signs stabilize (pulse, perfusion, mental status normalize)
• May require two IV lines or alternate access sites (venous cutdown, femoral vein, intraosseous infusion) for critically ill patients
• Frequently reassess hydration status to monitor adequacy of replacement

Transition to Oral Rehydration

Once mental status returns to normal, transition the remaining fluid deficit to oral intake. 1 This approach minimizes IV complications while maintaining effective rehydration. 2

Replacement of Ongoing Losses

During both IV and oral phases, continuously replace ongoing stool and vomit losses: 1

• 10 mL/kg for each watery or loose stool
• 2 mL/kg for each episode of emesis
• If measurable: 1 mL of ORS for each gram of diarrheal stool

Adjunctive IV Therapy for Metabolic Acidosis

Sodium bicarbonate should only be administered after effective ventilation and adequate fluid resuscitation with isotonic fluids have been established. 4

Bicarbonate dosing (when indicated for documented metabolic acidosis): 4

• Most patients require 2-5 mEq/kg
• Administer 1-2 mEq/kg over 4-8 hours
• Use 0.5 mEq/mL concentration for newborn infants
• Administer through a separate IV line when possible (do not mix with vasoactive amines or calcium)

Special Considerations for Cancer Treatment-Induced Diarrhea

For complicated cases with grade 3-4 chemotherapy-induced diarrhea: 1

• Administer IV fluids for severe dehydration
• Add octreotide 100-150 mcg SC three times daily or IV (25-50 mcg/h) if severely dehydrated
• Escalate octreotide up to 500 mcg until diarrhea controlled
• Add fluoroquinolone antibiotics
• Consider hospital admission

Common Pitfalls to Avoid

Do not withhold ORS in favor of IV fluids for mild-to-moderate dehydration — ORS is equally effective and avoids IV complications. 2

Do not use sports drinks, juice, or soft drinks for rehydration — incorrect osmolarity can worsen electrolyte imbalances. 2

Do not empirically prescribe antibiotics for simple watery diarrhea — this increases resistance and may worsen STEC infections. 2

Do not administer loperamide to children, or patients with bloody/febrile diarrhea — risk of toxic megacolon and cardiac events. 2, 5