What is the management of diarrhea and dehydration?

Management of Diarrhea and Dehydration

Definition and Etiology

Diarrhea with dehydration represents a fluid and electrolyte deficit resulting from excessive loss of water and electrolytes (sodium, chloride, potassium, and bicarbonate) in liquid stools. 1

• Mild dehydration is defined as 3-5% fluid deficit, characterized by increased thirst and slightly dry mucous membranes 2
• Moderate dehydration is 6-9% fluid deficit, presenting with loss of skin turgor, dry mucous membranes, and decreased urine output 2, 3
• Severe dehydration is ≥10% fluid deficit, manifesting as severe lethargy or altered consciousness, prolonged skin tenting, shock or near-shock 2

Evaluation of Dehydration

The most reliable clinical indicators are rapid deep breathing, prolonged skin retraction time, decreased perfusion, and capillary refill time. 2

• Assess pulse, perfusion, mental status, and measure body weight 1
• Sunken fontanelle and absence of tears are less reliable indicators than the above signs 2
• Capillary refill correlates with fluid deficit, though fever, ambient temperature, and age can affect this measurement 2

Management Algorithm

Step 1: Classify Dehydration Severity and Initiate Appropriate Rehydration

For Mild Dehydration (3-5% deficit):

• Administer oral rehydration solution (ORS) containing 50-90 mEq/L sodium at 50 mL/kg over 2-4 hours 1, 2
• Start with small volumes (one teaspoon) using a teaspoon, syringe, or medicine dropper, then gradually increase as tolerated 1
• Reassess hydration status after 2-4 hours; if still dehydrated, reestimate deficit and restart rehydration 1

For Moderate Dehydration (6-9% deficit):

• Use the same ORS procedure as mild dehydration but increase the volume to 100 mL/kg over 2-4 hours 1, 3
• Consider nasogastric administration if the patient cannot tolerate oral intake or is too weak to drink adequately 1
• Progress to maintenance therapy once rehydration is complete 3

For Severe Dehydration (≥10% deficit, shock, or altered mental status):

• This is a medical emergency requiring immediate IV rehydration with boluses of 20 mL/kg Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize 1, 2
• May require two IV lines or alternate access sites (venous cutdown, femoral vein, intraosseous infusion) 1
• Once consciousness returns, switch to ORS for the remaining estimated deficit 1
• Balanced crystalloid solutions (Ringer's lactate) likely result in slightly shorter hospital stays compared to 0.9% saline 4

For No Dehydration:

• Omit rehydration phase and start maintenance therapy immediately 1

Step 2: Replace Ongoing Fluid Losses

During both rehydration and maintenance, ongoing losses must be replaced continuously. 1

• Administer 10 mL/kg ORS for each watery or loose stool 1, 3
• Administer 2 mL/kg ORS for each episode of emesis 1, 3
• If losses can be measured accurately, give 1 mL ORS for each gram of diarrheal stool 1
• Use either low-sodium ORS (40-60 mEq/L) or standard ORS (75-90 mEq/L); when using the latter, provide additional low-sodium fluid (breast milk, formula, or water) 1

Step 3: Nutritional Management

Continue feeding throughout the illness—do not "rest the bowel." 2

For Infants:

• Breast-fed infants must continue nursing on demand throughout the diarrheal episode 1, 2
• Bottle-fed infants should receive full-strength, lactose-free, or lactose-reduced formulas immediately upon rehydration 1, 2
• When lactose-free formulas are unavailable, use full-strength lactose-containing formulas under supervision 1
• True lactose intolerance is diagnosed by worsening diarrhea upon lactose introduction, not by stool pH <6.0 or reducing substances >0.5% alone 1

For Older Children:

• Resume age-appropriate usual diet during or immediately after rehydration 1
• Recommended foods include starches, cereals, yogurt, fruits, and vegetables 1
• Avoid foods high in simple sugars and fats 1

Step 4: Medication Considerations

Antimotility Agents:

• Loperamide is contraindicated in all children <18 years of age with acute diarrhea 1, 5
• In immunocompetent adults with acute watery diarrhea, loperamide may be given but only after adequate hydration 1
• Avoid loperamide in suspected or proven inflammatory diarrhea, diarrhea with fever, or when toxic megacolon may result 1, 5
• Loperamide is contraindicated in children <2 years due to risks of respiratory depression and serious cardiac adverse reactions 5

Antiemetics:

• Ondansetron may be given to children >4 years and adolescents with vomiting to facilitate oral rehydration tolerance 1

Probiotics:

• May be offered to reduce symptom severity and duration in immunocompetent adults and children 1

Antimicrobials:

• In most people with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is not recommended 1
• Exceptions include immunocompromised patients or ill-appearing young infants 1

Step 5: Monitoring and Reassessment

• Reassess hydration status after 2-4 hours of rehydration therapy 1, 3
• Monitor pulse, perfusion, mental status, skin turgor, mucous membrane moisture, stool frequency, and consistency 3
• Continue ORS until diarrhea and vomiting are resolved 1

Critical Pitfalls to Avoid

• Never use soft drinks for rehydration due to high osmolality 2
• Do not withhold feeding or "rest the bowel"—this delays recovery 2
• Do not give antimotility agents to children or in inflammatory/febrile diarrhea 1, 5
• Do not use loperamide at higher than recommended doses due to cardiac risks including QT prolongation and Torsades de Pointes 5
• Do not overlook the need for fluid and electrolyte replacement—medication does not substitute for rehydration 1, 5
• Avoid loperamide in patients taking QT-prolonging drugs or with cardiac risk factors 5