What treatment can be given to an emergency room patient presenting with diarrhea, considering their past medical history, demographics, and potential for dehydration?

Treatment of Diarrhea in the Emergency Department

The cornerstone of treating diarrhea in the ER is rehydration therapy, with oral rehydration solution (ORS) as first-line for mild-to-moderate dehydration and intravenous isotonic fluids reserved for severe dehydration, shock, or ORS failure. 1

Initial Assessment and Fluid Management

Assess Hydration Status

• Mild-to-moderate dehydration (6-9% fluid deficit): decreased skin turgor, dry mucous membranes, sunken eyes, decreased urine output 2
• Severe dehydration (≥10% fluid deficit): altered mental status, shock, poor perfusion, inability to tolerate oral intake 1, 2

First-Line Rehydration Strategy

For mild-to-moderate dehydration:

• Administer reduced osmolarity ORS (<250 mmol/L) at 100 mL/kg over 2-4 hours 1, 2
• Commercial formulations include Pedialyte, CeraLyte, or Enfalac Lytren 1
• Do NOT use apple juice, Gatorade, or soft drinks 1
• Start with small volumes (one teaspoon) and gradually increase as tolerated 2

For severe dehydration:

• Administer isotonic IV fluids (lactated Ringer's or normal saline) at 60-100 mL/kg over 2-4 hours until pulse, perfusion, and mental status normalize 1
• Once stabilized, transition to ORS for remaining deficit replacement 1

Replace Ongoing Losses

• Children <10 kg: 60-120 mL ORS per diarrheal stool (up to ~500 mL/day) 2
• Children >10 kg: 120-240 mL ORS per diarrheal stool (up to ~1 L/day) 2
• Adults: Ad libitum ORS, up to ~2 L/day 2

Antimicrobial Therapy

In most cases of acute watery diarrhea without recent international travel, empiric antimicrobial therapy is NOT recommended 1

Exceptions where empiric antibiotics should be considered:

• Immunocompromised patients with severe illness and bloody diarrhea 1
• Young infants who appear ill 1
• Clinical features of sepsis with suspected enteric fever (use broad-spectrum therapy after cultures) 1

Critical contraindication:

• Avoid antibiotics in suspected STEC O157 or Shiga toxin 2-producing E. coli as this increases risk of hemolytic uremic syndrome 1

Adjunctive Symptomatic Therapies

Antimotility Agents (Loperamide)

Loperamide is CONTRAINDICATED in:

• All children <18 years of age 1
• Any patient with fever or bloody diarrhea (risk of toxic megacolon) 1
• Suspected inflammatory diarrhea 1
• Pediatric patients <2 years due to risk of respiratory depression and cardiac adverse reactions 3

Loperamide may be given to:

• Immunocompetent adults with acute watery diarrhea only after adequate hydration 1
• Use is not a substitute for fluid therapy 1

Important safety warning:

• Higher than recommended doses can cause life-threatening cardiac arrhythmias, QT prolongation, Torsades de Pointes, and death 3
• Avoid in patients taking QT-prolonging drugs or with cardiac risk factors 3

Antiemetics

Ondansetron may be given to:

• Children >4 years of age with vomiting to facilitate oral rehydration 1, 2
• Use only after adequate hydration is initiated 1

Probiotics

Probiotic preparations may be offered to:

• Immunocompetent adults and children to reduce symptom severity and duration 1
• Evidence supports use in infectious or antimicrobial-associated diarrhea 1

Nutritional Management

Resume feeding early:

• Continue breastfeeding throughout the diarrheal episode 1
• Resume age-appropriate diet during or immediately after rehydration 1
• Previously lactose-containing formula can be continued in most cases 1
• Diluted formula offers no benefit 1

Disposition Criteria

Discharge home if:

• Mild-to-moderate dehydration successfully corrected with ORS 2
• Patient tolerates oral intake 2
• Reliable follow-up available 2

Admit if:

• Severe dehydration requiring IV fluids 4
• Infants <3 months of age 4
• Persistent vomiting despite antiemetics 4
• Toxic appearance or suspected surgical abdomen 4
• Severe malnutrition 4

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 1
• Do not give loperamide to children or patients with bloody/febrile diarrhea - risk of toxic megacolon and serious cardiac events 1, 3
• Do not prescribe antibiotics empirically for simple watery diarrhea - increases resistance and may worsen STEC infections 1
• Do not use sports drinks or juice for rehydration - incorrect osmolarity can worsen electrolyte imbalances 1