Pyloromyotomy (Pyloric Stenosis)
Patient phenotype
Infant 3-12 weeks old, projectile non-bilious vomiting, dehydration. Hypochloremic, hypokalemic, metabolic alkalosis classic ('paradoxical aciduria' as a late finding). Surgery is NOT emergent — it's a metabolic emergency that needs correction first.
Procedure
Open or laparoscopic incision of the hypertrophied pylorus muscle (Ramstedt). Brief surgery (~30 min). The anesthetic challenge is the metabolic + airway management, not the procedure.
Anesthetic plan
Wait for fluid + electrolyte correction (Cl > 100, HCO3 < 30, K > 3.0) BEFORE going to OR. RSI with awake/semi-awake intubation classically (avoid muscle relaxant if possible). Standard pediatric anesthesia.
Setup
- ·Pediatric monitors + warming
- ·OG tube to decompress stomach pre-induction (suction in 4 quadrants — supine, left lateral, right lateral, prone)
- ·Pediatric airway cart
- ·Atropine drawn (sux pretreatment if needed)
- ·Fluid bolus already running (D5/0.45 NS at maintenance)
- ·Glucometer at bedside (these babies hypoglycemic)
Biggest concerns by phase
ELECTROLYTE CORRECTION FIRST — this is not an emergency
Hypochloremic hypokalemic metabolic alkalosis from prolonged vomiting. Risks: post-op apnea, arrhythmia, hypoventilation (respiratory compensation for alkalosis). Goals: Cl ≥ 100, HCO3 ≤ 30, K ≥ 3.0. Resuscitate with NS or D5/0.45 NS bolus 20 mL/kg + maintenance fluid.
Stomach decompression — full stomach by definition
OG tube before induction. Suction in all 4 positions (supine, left lateral, right lateral, prone) — gastric outlet obstruction means food/secretions trapped. Even after suction, treat as full stomach.
Awake / semi-awake intubation (classic teaching) vs. modern RSI
Classic teaching: awake intubation (intact reflexes protect airway). Modern practice: many centers do RSI with sux 2 mg/kg + atropine 0.02 mg/kg pretreatment, propofol 3 mg/kg + roc 1.2 mg/kg (with sugammadex available). Always have suction at the head of bed.
Hypoventilation risk — alkalosis depresses respiratory drive
Even after correction, the brain may take days to readjust. Watch ETCO₂ — these babies hypoventilate easily. Maintain normocapnia. Avoid opioids beyond minimal (use local infiltration + acetaminophen).
Post-op apnea risk — extubate awake + monitor
Post-op apnea risk in infants < 60 weeks post-conceptual age. Avoid opioids if possible. Monitor SpO₂ + apnea monitoring × 24 h post-op. May need overnight admission even for outpatient-style centers.
Hypoglycemia recurrence + early feeding
These infants hypoglycemic (poor PO intake + hyperinsulinemia from prior stomach distension). Continue D5 fluids until POing. Check glucose q1-2 h post-op. Surgeon usually starts feeds 4–6 hours postop if no leak suspected.
Mock-defense scenarios
Practice answering these out loud. The probes show what an examiner is listening for.
5-week-old infant for pyloromyotomy. Labs: Na 135, K 3.4, Cl 92, HCO3 32. Surgeon is asking when you can take the patient. What do you do?
What an examiner probes for
- ▹Recognizes inadequate correction (Cl < 100, HCO3 > 30)
- ▹Plan: continue NS or D5/0.45 NS bolus 20 mL/kg, recheck in 1-2 h
- ▹Communicate with surgeon: this is metabolic, not surgical urgency
- ▹Anticipates: post-op apnea + hypoventilation risk if uncorrected
Same baby, now Cl 102, HCO3 26, K 3.8. You're ready. Walk me through the induction.
What an examiner probes for
- ▹OG tube, suction in 4 positions before induction
- ▹Pre-oxygenate via mask, atropine pretreatment
- ▹Drug choice: classic awake/semi-awake vs. modern RSI rationale
- ▹Avoid opioids, use local + acetaminophen
Sources
- Coté Practice of Anesthesia for Infants
- AAP Pediatric Anesthesia 4e
- Holzman Pediatric Anesthesia 2e
Anatomy reference
Sourced reference images. 4 matches for "stomach pyloric digestive".
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