Emergency Medicine · Year 3 · from Emergency Medicine

Case 3: Pediatric Dehydration - The Vomiting Toddler

Patient Demographics

• Age: 18 months
• Sex: Male
• Accompanied by: Father

Chief Complaint

"He can't keep anything down and seems really tired."

History of Present Illness

Father brings 18-month-old son for evaluation of vomiting and lethargy. Illness began 36 hours ago with non-bloody, non-bilious vomiting (8-10 episodes). Diarrhea began 24 hours ago (watery, no blood, 6 episodes). Child has refused to drink and has had only 2 wet diapers in the last 24 hours (usually 6-8). Older sister had similar symptoms last week. Father reports child has become increasingly tired and "floppy."

Initial Assessment

Pediatric Assessment Triangle:

• Appearance: Lethargic, poor eye contact, minimal response to stimulation
• Work of Breathing: Normal
• Circulation: Pale, mottled extremities, cap refill 4 seconds

ESI Level: 2 - Moderate-severe dehydration with lethargy

Vital Signs:

• Heart rate: 168 bpm
• Respiratory rate: 28 breaths/min
• SpO2: 99% on room air
• Temperature: 37.4C
• Blood pressure: 82/48 mmHg (low for age)
• Weight: 10.2 kg (baseline 11.5 kg per father)

Weight Loss Calculation: (11.5 - 10.2) / 11.5 = 11.3% weight loss = SEVERE dehydration

Dehydration Assessment

Assessment: SEVERE dehydration (>10%)

Primary Survey

Airway: Patent Breathing: Normal rate and effort Circulation: Tachycardic, hypotensive, delayed cap refill, weak pulses - SHOCK Disability: Lethargic but responds to painful stimuli, GCS 12 (E3V4M5) Exposure: Sunken eyes, dry mucous membranes, tenting skin

Immediate Resuscitation

IV Access:

• Peripheral IV attempted x2 - unsuccessful (poor veins)
• IO access placed in proximal tibia

Fluid Resuscitation:

• Normal saline 20 mL/kg bolus (200 mL) over 20 minutes
• Reassess after each bolus

Response to First Bolus:

• HR: 152 (improved)
• BP: 88/54 (improved)
• Cap refill: 3 seconds (improved)
• Mental status: More alert

Second Bolus:

• Additional NS 20 mL/kg given
• Continued improvement in perfusion

Secondary Survey

SAMPLE History:

• Symptoms: Vomiting, diarrhea, lethargy, decreased urine output
• Allergies: None
• Medications: None
• PMH: Healthy, immunizations up to date
• Last Meal: Small amount of water this morning, vomited
• Events: Sick contact (sibling with gastroenteritis)

Physical Examination (After Initial Resuscitation):

General: More alert, still appears ill

HEENT:

• Sunken eyes (improving)
• Dry mucous membranes
• No oral lesions

Cardiovascular:

• Tachycardic, improved perfusion
• Strong central pulses, weak peripheral

Abdomen:

• Soft, mildly distended
• Hyperactive bowel sounds
• No tenderness

GU:

• Dry diaper

Skin:

• Tenting improved
• No rashes

Neuro:

• More interactive
• Age-appropriate responses

Diagnostic Testing

Point-of-Care:

• Glucose: 68 mg/dL (low normal, give dextrose-containing fluids)
• Urine: Unable to obtain (minimal output)

Labs:

• BMP: Na 148, K 3.2, Cl 118, HCO3 16, BUN 32, Cr 0.8
• Glucose: 72
• VBG: pH 7.28, pCO2 28

Interpretation:

• Hypernatremic dehydration (Na 148)
• Hypokalemia (K 3.2)
• Metabolic acidosis with respiratory compensation
• Elevated BUN/Cr ratio (prerenal azotemia)

Diagnosis

Acute viral gastroenteritis with severe hypovolemic shock and hypernatremic dehydration

Management

After Resuscitation Phase:

1. Maintenance + Deficit Replacement:

• Fluid: D5 0.45% NS with 20 mEq/L KCl
• Calculate 48-hour correction (hypernatremia correction)
• Goal: Lower Na by max 0.5 mEq/L/hour (risk of cerebral edema if too fast)

1. Monitoring:

• Strict I/O
• Serial electrolytes every 4-6 hours initially
• Daily weights
• Neuro checks (for cerebral edema)

1. Nutrition:

• NPO initially, then advance diet slowly
• Oral rehydration when tolerating

Clinical Course

At 12 hours:

• HR: 120, BP: 94/58
• Na: 145 (appropriate rate of decline)
• Tolerating small amounts of Pedialyte
• Voiding

At 24 hours:

• Na: 142
• Tolerating regular diet
• Active, playful

Disposition

• Admitted for IV rehydration
• Transitioned to oral fluids at 24 hours
• Discharged home at 36 hours
• Education on oral rehydration for gastroenteritis
• Return precautions provided

Teaching Points

1. Assess dehydration severity: Clinical signs correlate with fluid deficit; weight loss is gold standard if known
2. Don't delay IV/IO for lab results: Shock requires immediate fluid resuscitation
3. 20 mL/kg boluses: Repeat and reassess until perfusion improves
4. Hypernatremic dehydration: Common in young children; correct slowly to avoid cerebral edema
5. Oral rehydration: First-line for mild-moderate dehydration; ondansetron may help success
6. IO access: Don't hesitate if IV difficult; especially in decompensating child
7. Most gastroenteritis is viral: Antibiotics rarely indicated; supportive care is mainstay

Clinical Image

Image Description: Comparison images demonstrating clinical signs of dehydration in pediatric patients, including sunken eyes, decreased skin turgor (tenting), and dry mucous membranes. These findings help clinicians estimate the degree of dehydration.

Attribution: Image from Wikimedia Commons, Signs of dehydration. Licensed under CC BY-SA 3.0. Source: https://commons.wikimedia.org/wiki/File:Dehydration_signs.svg

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