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  • Incidence 2–4:1,000 live births
  • Male to female 4:1
  • Usual age of presentation is 2 weeks to 2 months
  • Symptoms:
    • Persistent nonbilious “projectile” vomiting with feeds
    • Dehydration and electrolyte abnormalities:
      • Hypokalemia, hypochloremia, metabolic alkalosis
      • If dehydration is severe, may see mixed metabolic acidosis
      • If patient is still alkalotic postoperatively, hypoxia can occur as the baby attempts to correct the alkalotic state by hypoventilating
    • “Olive” palpable in hypogastric area on exam
    • Not often associated with other abnormalities


  • Medical emergency, not surgical emergency
  • Make sure patient is normovolemic and electrolyte abnormalities have been corrected. Serum values of bicarbonate, chloride, and potassium should be within normal limits. However, the most useful measure of adequate resuscitation is the clinical assessment—adequate urine output (minimum of 1 mL/kg/h), skin turgor, heart rate, etc
  • Children with severe dehydration should receive deficit fluid therapy with isotonic crystalloid solution (10–20 mL/kg) initially. However, ongoing resuscitation should be performed with 0.45% NaCl in D5W at a rate of approximately 1.5–2.0× maintenance to prevent rapid changes in volume and electrolyte levels, which can result in seizures
  • When urine output has been demonstrated, potassium chloride (10–20 mEq/L) can be added to the fluids
  • Resuscitation may take 48–72 hours, depending on degree of dehydration
  • Vitamin K given if needed


  • Standard monitors: NIBP, EKG, SpO2, temperature


  • GA most common, but regional (spinal, epidural, and caudal) has been used with success
  • Perceived advantage is the minimization of respiratory depressant use and risk of apnea postoperatively
  • Required analgesic level for pyloromyotomy is between T4 and T10 for open cases, depending on incision location (see “Surgical approach” below in the Maintenance section)
  • Epidural:
    • Single-shot epidural in left lateral position at T10–11
    • Use 20G, 50 mm Tuohy needle with LOR to saline (to minimize risk of air embolization). A catheter can also be threaded if needed
    • Ropivacaine 0.75% (0.75 mL/kg)
  • Caudal:
    • Caudal blockade with bupivacaine 0.25%
    • Difficult to obtain a sufficient thoracic level from a caudal
    • 1.6 mL/kg for pyloromyotomy achieved a success rate of 96% in one study
  • Spinal:
    • 25G (0.6 × 30 mm) or 23G (0.50 × 51 mm) neonatal LP needle
    • Isobaric bupivacaine (5 mg/mL), 0.7–0.8 mg/kg, without epinephrine is injected using a 1-mL syringe
    • Adequacy of SA determined by the presence of profound motor block in the lower extremities, inability to move feet, knees, and legs, and the absence of a skin prick response at the level of the surgical incision
    • IV sedation (midazolam 0.1 mg/kg) can be used before or during the operation if the child is crying/restless in the presence of adequate SA
    • However, patient remains at high risk for aspiration; sedation should be used either sparingly or not at all
    • Surgical time is often limited to <90 minutes, as the duration of spinal blockade in this patient population is less than that observed in adults


  • High aspiration risk
  • RSI versus awake intubation
  • Prior to induction, stomach is emptied with orogastric/nasogastric tube. Patient is positioned supine, right lateral and left lateral during suctioning to ensure optimal evacuation of stomach secretions


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