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Pyloric Stenosis — FRCA Final MCQ

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ModeratePaediatric AnaesthesiaPyloric StenosisFRCA Final

A 6-week-old, 4 kg infant is scheduled for pyloromyotomy. Dehydration and hypochloraemic metabolic alkalosis have been corrected, blood glucose is normal, and the stomach has been thoroughly aspirated through a gastric tube immediately before induction. Which induction plan best balances the risks of pulmonary aspiration and rapid hypoxaemia?

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Reveal the answer and explanation

Correct answer: B — Sevoflurane inhalational induction, non-depolarising neuromuscular block, gentle mask ventilation, then tracheal intubation

Explanation lettering: E = shown as A · C = shown as B · D = shown as C · B = shown as D · A = shown as E

C is an appropriate controlled induction technique after full resuscitation and careful gastric aspiration. Sevoflurane permits maintenance of ventilation while a non-depolarising neuromuscular blocker takes effect, reducing the rapid desaturation associated with an apnoeic classic RSI in infants. The trachea is then intubated under optimal conditions. Gastric drainage reduces but does not abolish aspiration risk, so a protected tracheal airway remains appropriate. Options A and B impose an apnoeic interval and may cause severe hypoxaemia; routine cricoid pressure can also impair laryngoscopy in an infant. Options D and E delay definitive airway protection, while a supraglottic airway is inappropriate for gastric outlet obstruction. Importantly, pyloromyotomy should not proceed while the infant remains hypovolaemic or alkalotic.

Reference: Scrimgeour GE, Leather NW, Perry RS, Pappachan JV, Baldock AJ. Gas induction for pyloromyotomy. Paediatric Anaesthesia. 2015;25:677-680. https://pubmed.ncbi.nlm.nih.gov/31361669/