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Difficulty: EasyPediatric Gastrointestinal Disorders

A first-time mother brings her 44-week-old boy to the acute care clinic because he has been forcefully vomiting after every meal for the last 4848 hours. The vomit does not contain bile. She notes that he appears extremely hungry and eagerly attempts to feed again immediately after these episodes. Vital signs reveal a heart rate of 162 beats/min162 \text{ beats/min} and a respiratory rate of 32 breaths/min32 \text{ breaths/min}. On physical examination, the infant has dry mucous membranes, a sunken anterior fontanelle, and delayed capillary refill. Careful abdominal palpation reveals a firm, olive-shaped mass in the right upper quadrant.

Laboratory analysis demonstrates:

Laboratory ParameterResult
Sodium131 mEq/L131 \text{ mEq/L}
Potassium2.9 mEq/L2.9 \text{ mEq/L}
Chloride92 mEq/L92 \text{ mEq/L}
Bicarbonate36 mEq/L36 \text{ mEq/L}

Which of the following represents the most appropriate initial step in the care of this patient?

  1. Initiation of intravenous fluid and electrolyte resuscitationAnswer
  2. B
    Immediate transfer to the operating room for a pyloromyotomy
  3. C
    Endotracheal intubation to manage the severe metabolic alkalosis
  4. D
    Abdominal computed tomography scan to evaluate for anatomical obstruction
  5. E
    Administration of broad-spectrum intravenous antibiotics

Answer

Initiation of intravenous fluid and electrolyte resuscitation
The correct answer emphasizes that the patient requires immediate medical optimization. Hypertrophic pyloric stenosis typically presents at 33 to 66 weeks of age with nonbilious, projectile vomiting. The loss of gastric hydrochloric acid leads to a hypochloremic, hypokalemic metabolic alkalosis. Although the definitive treatment is a surgical pyloromyotomy, it is considered a medical emergency, not a surgical one. The patient must first receive aggressive intravenous fluid resuscitation with normal saline to restore intravascular volume, followed by maintenance fluids with added potassium. Surgery is delayed until the electrolyte abnormalities and acid-base status are fully normalized to prevent fatal postoperative apnea caused by respiratory depression.

Step-by-Step Solution

1
Identify the underlying diagnosis from the clinical presentation.
The patient has hypertrophic pyloric stenosis.
The infant presents with the classic triad of nonbilious projectile vomiting, an olive-shaped abdominal mass, and hypochloremic, hypokalemic metabolic alkalosis.
2
Assess the patient's physiological status and stability.
The patient is severely dehydrated and has significant metabolic derangements.
Clinical signs (tachycardia, dry mucous membranes, sunken fontanelle) and lab values confirm substantial volume depletion and electrolyte loss from recurrent vomiting.
3
Determine the most appropriate initial management step.
Intravenous fluid and electrolyte resuscitation is the priority.
Medical optimization (correcting the alkalosis and dehydration) is mandatory before definitive surgical intervention (pyloromyotomy) to minimize severe anesthetic risks, such as postoperative apnea.

Key Concept

In hypertrophic pyloric stenosis, the initial management must focus on correcting dehydration and the characteristic hypochloremic, hypokalemic metabolic alkalosis with intravenous fluids prior to surgical intervention.
Estimated Time:1m 0s
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Topics

Pediatric Gastrointestinal Disorders

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