Pyloric stenosis

Pyloric stenosis

Other names	Infantile hypertrophic pyloric stenosis, IPHS
Anesthetic relevance	Critical
Anesthetic management	Delay surgery to correct electrolyte abnormalities and hypovolemia Decompress stomach prior to induction Modified RSI
Specialty	Pediatric surgery
Signs and symptoms	Projectile vomiting
Diagnosis	Ultrasound
Treatment	Fluid resuscitation Correction of electrolytes Surgery
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Pyloric stenosis (also called infantile hypertrophic pyloric stenosis, IHPS) is a disorder of early infancy caused by hypertrophy of the pylorus which leads to a narrowing of the opening from the stomach to the first part of the small intestine. This can cause an obstruction of the gastric outlet, leading to projectile vomiting without the presence of bile.

Anesthetic implications

Preoperative optimization

• Delay surgery for fluid resuscitation and electrolyte correction
  • Procedure is urgent but not emergent
• Recommended preoperative thresholds include:
  • pH ≤7.45 (base excess ≤3.5)
  • Bicarbonate <26 mmol/L
  • Sodium ≥132 mmol/L
  • Potassium ≥3.5 mmol/L
  • Chloride ≥100 mmol/L
  • Glucose ≥4.0 mmol/L (72 mg/dL)

Intraoperative management

• Decompress stomach via OG or NG prior to induction
  • Supine, left lateral decubitus, and right lateral decubitus positions
• Modified RSI IV induction
  • No increased risk of aspiration compared to traditional RSI
  • Traditional RSI leads to more hypoxia
• Extubate awake

Postoperative management

• Feeding can resume within hours after surgery
  • Modest regurgitation is not uncommon and should not delay feeding

Related surgical procedures

• Pyloromyotomy

Pathophysiology

Gastric outlet obstruction due to hypertrophy of the pylorus impairs emptying of gastric contents into the duodenum. Thus, stomach contents can only exit via vomiting. This leads to a number of physiologic derangements, including:

• Metabolic alkalosis
  • Respiratory compensation with hypoventilation and increased arterial pCO₂
• Secondary hyperaldosteronism from decreased blood volume
  • Hypokalemia
  • ± Hypernatremia
• Hypochloremia

Signs and symptoms

• Progressively worsening vomiting in the first weeks to 3 months of life
• Dehydration
• Poor feeding and weight loss
• Palpable "olive-like" mass in right upper quadrant of abdomen

Diagnosis

• Ultrasound

Treatment

Medication

• IV fluid resuscitation
• Correction of electrolytes
• Atropine can be used as an alternative to surgical correction with an 85-89% success rate

Surgery

A pyloromyotomy is the definitive treatment for pyloric stenosis. The procedure is most commonly performed laparoscopically, but can be performed open via a small incision. Incomplete correction requiring repeat surgery is rare.

Prognosis

Once corrected, pyloric stenosis generally has no long-term side effects or impact on the child's future health.

Epidemiology

• Male > female
  • Firstborn males 4x likely
• Caucasian > Hispanic > Black ≈ Asian
• Exposure to erythromycin