What is the initial management for a patient presenting with diarrhoea, considering their past medical history, demographics, and potential underlying causes?

Management of Diarrhoea

Immediate Rehydration is the Priority

Oral rehydration therapy (ORT) using WHO-recommended oral rehydration solution (ORS) is the cornerstone of initial management for all patients with diarrhoea who can tolerate oral fluids, regardless of the underlying cause 1, 2. This approach is lifesaving, less painful, safer, and more cost-effective than intravenous therapy 1.

Assess Hydration Status First

Rapidly evaluate the severity of dehydration through clinical examination 1, 2:

• Mild dehydration (3-5% fluid deficit): Assess for thirst, slightly decreased skin turgor, moist mucous membranes 2
• Moderate dehydration (6-9% fluid deficit): Look for postural light-headedness, reduced urination, tachycardia, orthostatic hypotension, sunken eyes 1, 2
• Severe dehydration (≥10% fluid deficit): Identify lethargy, altered mental status, decreased skin turgor, absent peripheral pulses, hypotension, oliguria 1, 2, 3

Rehydration Protocol Based on Severity

Mild Dehydration

• Administer ORS containing 50-90 mEq/L sodium at 50 mL/kg over 2-4 hours 2
• Continue breastfeeding if applicable 2
• Resume age-appropriate diet immediately after initial rehydration 2

Moderate Dehydration

• Increase ORS volume to 100 mL/kg over 2-4 hours 2
• If patient cannot tolerate oral fluids due to persistent vomiting, escalate to IV therapy 2, 3

Severe Dehydration (Medical Emergency)

• Establish immediate IV access and administer 20 mL/kg boluses of lactated Ringer's solution or normal saline rapidly 2, 3
• Repeat boluses until vital signs stabilize (pulse normalizes, perfusion improves, mental status clears) 3
• Once stabilized, transition to ORS to complete rehydration 1

Replace Ongoing Losses

• Continuously replace stool losses with 10 mL/kg for each watery stool 3
• Replace vomit losses with 2 mL/kg for each episode of emesis 3
• Maintain urine output >0.5 mL/kg/h as a target 1

Obtain Targeted Clinical History

Identify features that determine management approach 1:

Inflammatory vs. Non-inflammatory Diarrhoea:

• Red flags for inflammatory diarrhoea: Fever, visible blood or mucus in stool, severe abdominal pain, tenesmus 1, 2
• Watery diarrhoea: Suggests non-inflammatory causes (viral, enterotoxigenic bacteria, malabsorption) 1

Epidemiological Risk Factors:

• Recent travel to developing areas 1
• Day-care center exposure 1
• Consumption of unsafe foods (raw meats, eggs, shellfish, unpasteurized products) 1
• Contact with animals or ill persons 1
• Recent antibiotic use (consider Clostridioides difficile) 1
• Immunocompromised status (AIDS, immunosuppressive medications) 1

When to Use Antimotility Agents

Loperamide can be used ONLY in uncomplicated, non-inflammatory diarrhoea 1, 4:

• Initial dose: 4 mg, then 2 mg after each unformed stool (maximum 16 mg/day) 1, 4
• Contraindications 2, 4:
  • Children <2 years of age (risk of respiratory depression and cardiac toxicity) 4
  • Presence of fever, bloody stools, or mucus (inflammatory diarrhoea) 2, 4
  • Suspected C. difficile infection 4
  • Patients taking QT-prolonging medications 4

When to Obtain Stool Studies

Order stool evaluation for 1:

• Inflammatory features: Fever, bloody/mucous stools, severe abdominal pain 1
• Severe or persistent symptoms: Duration >7 days, severe dehydration, immunocompromised patients 1
• Specific testing: Stool culture for Salmonella, Shigella, Campylobacter, E. coli O157:H7; C. difficile toxin; ova and parasites 1
• Fecal leukocytes or lactoferrin: Helps identify inflammatory diarrhoea 1

Complicated Diarrhoea Requiring Hospitalization

Admit patients with 1:

• Severe dehydration despite oral rehydration attempts 1
• Sepsis features (fever with altered mental status, hypotension) 1, 2
• Neutropaenia with diarrhoea (risk of neutropaenic enterocolitis) 1
• Persistent vomiting preventing oral intake 1
• Infants <3 months of age 5

Hospital management includes 1:

• IV fluids and electrolyte replacement 1
• Broad-spectrum antibiotics if sepsis or neutropaenic enterocolitis suspected (piperacillin-tazobactam or imipenem-cilastatin) 1
• Octreotide 100-150 mcg subcutaneously three times daily for refractory cases, escalating to 500 mcg if needed 1

Critical Pitfalls to Avoid

• Never use loperamide in inflammatory diarrhoea: This can precipitate toxic megacolon, especially in patients with Shigella, C. difficile, or inflammatory bowel disease 2, 4
• Do not delay IV fluids in severe dehydration: Attempting oral rehydration in shock wastes critical time 3
• Avoid normal saline or 5% glucose alone for severe cases: These worsen acidosis and can lead to cardiac overload 6
• Do not withhold food after rehydration: Early refeeding reduces stool output and improves outcomes 1, 2

Electrolyte Monitoring

• Check serum electrolytes, particularly potassium, in patients with severe or prolonged diarrhoea 1, 7
• Hypokalemia is common and often undertreated: Standard ORS may not provide adequate potassium replacement 7
• Monitor for metabolic acidosis in severe cases; consider sodium bicarbonate only after adequate fluid resuscitation 3