What is the management for a 2-year-old child with vomiting and metabolic acidosis?

Management of a 2-Year-Old with Vomiting and Metabolic Acidosis

The management of a 2-year-old with vomiting and metabolic acidosis (CO2 of 17) should focus on aggressive rehydration with appropriate fluids while monitoring electrolytes and addressing the underlying cause.

Initial Assessment and Stabilization

Assess Hydration Status

• Evaluate for signs of dehydration:
  • General appearance
  • Eyes (sunken or not)
  • Mucous membranes (dry or moist)
  • Tears (present or absent)
  • Capillary refill time (normal < 2 seconds)
  • Urine output (target ≥0.5 ml/kg/h)
  • Vital signs, especially heart rate and blood pressure 1, 2

Rule Out Red Flag Signs

• Bilious or bloody vomiting
• Altered mental status
• Toxic/septic appearance
• Inconsolable crying or excessive irritability
• Severe dehydration
• Signs of hypoglycemia
• Bent-over posture 3

Rehydration Strategy

Oral Rehydration (If Tolerated)

• Use oral rehydration solution (ORS) with appropriate composition:
  • Sodium: 75-90 mEq/L
  • Potassium: 20 mEq/L
  • Chloride: 65-80 mEq/L
  • Citrate: 10 mEq/L
  • Glucose: 75-111 mmol/L
  • Total osmolarity: 245-311 mOsm/L 4
• Commercial products like Pedialyte (45 mEq/L sodium) are suitable 4

Intravenous Rehydration (If Needed)

• For moderate to severe dehydration or if oral rehydration fails:
  • Initial bolus: 20-40 ml/kg of 0.9% saline 1
  • Monitor response to fluid resuscitation
  • Adjust subsequent fluid therapy based on clinical response

Addressing Metabolic Acidosis

Correct Electrolyte Abnormalities

• Monitor and correct electrolytes according to the following guidelines:
  • Glucose: If < 3 mmol/l, give 5 ml/kg of 10% dextrose
  • Potassium: If < 3.5 mmol/l, give 0.25 mmol/kg over 30 min
  • Total calcium: If < 2 mmol/l, give 0.3 ml/kg 10% Ca gluconate over 30 min
  • Magnesium: If < 0.75 mmol/l, give 0.2 ml/kg 50% MgSO4 over 30 min
  • Phosphate: If < 0.7 mmol/l, give 0.2 mmol/kg of NaPO4 over 30 min 1

Manage Metabolic Acidosis

• Metabolic acidosis typically resolves with correction of hypovolemia and treatment of any underlying anemia 1
• Avoid sodium bicarbonate administration as there is no evidence supporting its use 1
• Maintain adequate hydration with appropriate fluids containing glucose to prevent hypoglycemia 1, 5

Nutrition Management

• Resume age-appropriate diet immediately after initial rehydration (within 4-6 hours)
• Offer food every 3-4 hours
• Avoid foods high in simple sugars and fats
• Continue breastfeeding throughout the illness if applicable 4
• Ensure calorie-containing fluids rather than just water or diet beverages to prevent starvation ketoacidosis 5

Diagnostic Workup

Laboratory Tests

• Serum electrolytes and blood gases (to assess acidosis and electrolyte abnormalities)
• Blood glucose (to rule out diabetic ketoacidosis)
• Renal and liver function tests
• Consider lactate level if sepsis is suspected 3

Additional Investigations (Based on Clinical Suspicion)

• Abdominal imaging if surgical cause is suspected
• Stool studies if infectious gastroenteritis is suspected
• Metabolic workup if inborn error of metabolism is suspected 3, 6

Differential Diagnosis to Consider

1. Gastroenteritis (most common cause) 4, 3
2. Starvation ketoacidosis (especially if only consuming calorie-free beverages) 5
3. Diabetic ketoacidosis (ruled out if normal glucose)
4. Inborn errors of metabolism
5. Pyloric stenosis (can cause hypochloremic metabolic alkalosis, but consider in persistent vomiting) 7
6. Surgical causes (e.g., intussusception, appendicitis) 6
7. Sepsis or other serious infection

Monitoring and Follow-up

• Monitor vital signs, urine output, and mental status
• Serial electrolyte measurements until normalized
• Reassess hydration status regularly
• Consider escalation of care if:
  • Symptoms worsen
  • Unable to maintain hydration orally
  • Development of high fever, bloody diarrhea, or severe abdominal pain 4

Common Pitfalls and Caveats

1. Failing to recognize that metabolic acidosis in a vomiting child could indicate a serious underlying condition beyond simple gastroenteritis
2. Not providing adequate glucose in rehydration fluids, which can worsen ketoacidosis
3. Missing surgical causes of vomiting that require prompt intervention
4. Overlooking electrolyte abnormalities that require specific correction
5. Using diet beverages or plain water for rehydration, which lack calories and can worsen starvation ketoacidosis 5