What are the next steps for a 45-day-old infant presenting with diarrhea?

Management of Diarrhea in a 45-Day-Old Infant

Immediately assess the infant's hydration status by examining capillary refill time, skin turgor, mucous membranes, mental status, and pulse, then initiate oral rehydration therapy with ORS based on the degree of dehydration while continuing breastfeeding. 1, 2

Initial Assessment

Determine the degree of dehydration using the following clinical signs:

• Capillary refill time is the most reliable predictor of dehydration in infants this age 1
• Examine skin turgor, mucous membranes, mental status, and pulse 1, 2
• Look for sunken eyes, dry oral mucosa, and altered neurologic status as key indicators 3
• Weigh the infant to establish baseline and calculate fluid deficit 4

Categorize dehydration severity:

• Mild (3-5% fluid deficit): Minimal clinical signs 1, 2
• Moderate (6-9% fluid deficit): Noticeable clinical signs present 1, 2
• Severe (≥10% fluid deficit): Shock or near-shock with significantly altered perfusion 1, 2

Rehydration Protocol

For mild dehydration (3-5% deficit):

• Administer 50 mL/kg of ORS over 2-4 hours 1, 4, 2
• Use ORS containing 50-90 mEq/L of sodium 1, 4

For moderate dehydration (6-9% deficit):

• Administer 100 mL/kg of ORS over 2-4 hours 1, 4, 2
• Give small volumes initially using a teaspoon, syringe, or medicine dropper 1

For severe dehydration (≥10% deficit):

• This is a medical emergency requiring immediate IV rehydration 1, 2
• Administer 20 mL/kg boluses of Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize 1
• Transition to oral rehydration once consciousness returns 1

For infants unable to drink but not in shock:

• Use a nasogastric tube to administer ORS at 15 mL/kg/hour 1

Critical Technique for Vomiting Infants

If the infant is vomiting, do NOT allow large volume drinking:

• Give 5-10 mL of ORS every 1-2 minutes using a spoon or syringe 2
• Gradually increase the amount as tolerated 2
• Common pitfall: Allowing a thirsty infant to drink large volumes ad libitum will worsen vomiting 2

Ongoing Loss Replacement

After initial rehydration, replace continuing losses:

• Give 10 mL/kg of ORS for each watery stool 1, 4, 2
• Give 2 mL/kg of ORS for each episode of vomiting 1, 4, 2

Feeding Management

Continue breastfeeding throughout the entire episode:

• Never stop breastfeeding during diarrhea or rehydration 1, 4, 2
• Breastfeeding reduces severity and duration of diarrhea 5

For formula-fed infants:

• Resume appropriate formula immediately after rehydration 4
• Do NOT use lactose-free formulas as they have no demonstrated benefit 5

Reassessment and Monitoring

Reassess hydration status after 2-4 hours:

• If rehydrated, transition to maintenance phase 1, 4, 2
• If still dehydrated, recalculate fluid deficit and restart rehydration 1, 4

Instruct caregivers to return immediately if:

• Infant continues passing many watery stools 1
• Develops fever 1
• Shows increased thirst or sunken eyes 1
• Appears to be worsening 1
• Develops bloody diarrhea (dysentery) - requires immediate evaluation for antimicrobial therapy 2
• Shows signs of intractable vomiting preventing oral rehydration 2
• Has high stool output (>10 mL/kg/hour) 2

What NOT to Do

Avoid the following:

• Do NOT use cola drinks or soft drinks - they contain inadequate sodium and excessive osmolality that worsens diarrhea 1, 5
• Do NOT use antidiarrheal medications - they are contraindicated in children and do not prevent dehydration 2, 5
• Do NOT delay feeding until diarrhea stops - there is no justification for "bowel rest" 1