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Common intestinal occlusive disorder appearing during the first weeks of life typically characterized explosive vomiting following feeding, progressive dehydration, and hypochloremic alkalosis. It is a common infantile disorder characterized by enlarged pyloric musculature leading to gastric outlet obstruction.

Infantile Hypertrophic Pyloric Stenosis

1:300 live births with considerable regional variation. Of the affected infants, 85% are male, with 5.7:1 male-to-female ratio. Approximately 10% are premature infants.

Mendelian inheritance of pyloric stenosis cannot be established.

Physiopathologic mechanism is not known, but a defect in pyloric relaxation (pylorospasm) has been postulated. The pylorospasm may be the result of a lack of nitric oxide synthase in pyloric tissue.

Nonbilious projectile vomiting, palpable pyloric tumor with visible peristalsis in the upper abdomen in a male infant aged 3 to 8 weeks. Confirmed diagnosis by ultrasonography. Typical laboratory finding is hypochloremic alkalosis.

Dehydration and electrolyte derangement are common (hypochloremic hypokalemic metabolic alkalosis). Full correction of the intravascular volume and of chloride and potassium deficits must be done prior to surgery and may require several days to ensure safe anesthesia and surgery. Pyloromyotomy (Ramstedt operation) remains the only satisfactory treatment, with a very low perioperative mortality rate of 0.4 to 3%. Occasional vomiting occurs postoperatively in more than half of patients, but the value of graded postoperative feeding regimen is not proven. Associated renal anomalies may occur in a small percentage of patients.

This is a medical emergency, not a surgical one. Ensure that the intravascular volume and electrolyte deficits are fully corrected prior to anesthesia. Investigations include serum electrolytes, urea, creatinine, and blood sugar levels. Arterial blood gas analysis for acid-base values might be indicated in severe cases. Urine chloride concentration is indicative of the degree of hypokalemia.

All precautions should be taken to protect against a full stomach. The nasogastric tube should be aspirated prior to induction of anesthesia. A rapid-sequence induction with preoxygenation, cricoid pressure, thiopental, and succinylcholine is often used. Inhalation induction with cricoid pressure applied until orotracheal intubation is achieved is another alternative. Awake tracheal intubation is not superior to anesthetized, paralyzed tracheal intubation technique in maintaining adequate oxygenation and heart rate or in reducing complications. Most important for the anesthesiologist is to use the airway management technique that he/she is most comfortable with. It is not time to improvise! Blood loss usually is minimal. The infant should have his/her trachea extubated fully awake at the end of the procedure in the left lateral position. Postoperative analgesia can be provided by wound infiltration with local anesthetics and administration of acetaminophen. Postoperative hypoglycemia 2 to 3 hours after the procedure and respiratory depression have been described. Consequently, the child should be monitored closely in the immediate postoperative period.

There are no specific implications except for a significant increase in susceptibility to opiates.

Bissonnette B, Sullivan PJ: Pyloric stenosis. Can ...

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