Unexpected difficult mask ventilation in a child for tonsillectomy
A 6-year-old boy weighing 20 kg is scheduled for tonsillectomy. He has a history of snoring and recurrent tonsillitis, and his tonsils are described as kissing. He is otherwise well, with no known allergies. He has a fear of needles and is very anxious. The anaesthesia provider plans an inhalational induction with sevoflurane and oxygen, followed by insertion of a supraglottic airway. After 4 minutes at 6% sevoflurane, the child is unresponsive but the jaw is tight, the oxygen saturation is falling from 98% to 88%, and there is no capnography trace. The assistant cannot achieve a seal with the face mask.
1. What is your immediate differential diagnosis and how would you manage the airway in the next 60 seconds?
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Differential:
- Airway obstruction from large tonsils and loss of tone (most likely).
- Laryngospasm triggered by secretions or light anaesthesia.
- Inadequate depth of anaesthesia causing breath-holding or coughing.
- Equipment problem: mask leak, disconnection, or capnography sampling failure.
Immediate management (next 60 seconds):
- Call for help and check the equipment: is the mask connected, is the oxygen flowing, is the capnography line patent?
- Reposition: head tilt with jaw thrust, insert an oropharyngeal airway if tolerated, and apply continuous positive airway pressure (e.g., 10–15 cmH₂O) with a tight two-person mask technique.
- Deepen anaesthesia if laryngospasm is suspected: increase sevoflurane to 8% and consider a small dose of propofol (0.5–1 mg/kg IV) if IV access exists; if not, maintain inhalational anaesthesia.
- Suction the pharynx if secretions are present.
- If saturation continues to fall below 85%, give suxamethonium 1–2 mg/kg IM (or IV if access is available) to break laryngospasm and secure the airway with intubation.
- Confirm ventilation with capnography and auscultation before proceeding.
Document the event and the interventions.
2. The child is now stable with a supraglottic airway and spontaneous ventilation. How would you plan the rest of the anaesthetic and the emergence?
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Maintenance:
- Keep the child spontaneously breathing with sevoflurane in oxygen/air, aiming for a steady end-tidal concentration of about 2.5–3%.
- Ensure adequate analgesia: give paracetamol 15 mg/kg IV and an opioid such as morphine 0.1 mg/kg IV or fentanyl 1–2 µg/kg, titrated to effect.
- Consider dexamethasone 0.15 mg/kg IV for antiemesis and airway oedema, and ondansetron 0.1 mg/kg IV.
- Monitor capnography, saturation, heart rate, and blood pressure throughout.
Emergence:
- The child is at risk of laryngospasm and bleeding, so I would remove the supraglottic airway only when the child is awake and breathing reliably, or use a deep removal technique with suction ready - the choice depends on the child's response.
- Position the child semi-prone or lateral with suction immediately available.
- Have a plan for re-intubation if bleeding or obstruction occurs.
- Observe in recovery for at least 30 minutes, monitoring for bleeding, stridor, and desaturation.
Communication: Inform the parents about the event and the plan, and document the difficult airway in the notes for future anaesthetics.