Obstetric anaesthesia12 / 17
Anterior mediastinal mass at term for caesarean26-year-old woman, 62 kg, at 37 weeks; anterior mediastinal mass found 2 weeks ago
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Know this first
- Supine breathlessness or cough warns of airway obstruction at induction.
- Over 50% tracheal compression on CT raises risk.
- Rigid bronchoscope and surgeon present; keep spontaneous breathing.
- Bypass 'standby' is too slow; cannulate before induction if GA is unavoidable.
- First rescues: change position, or rigid bronchoscopy past the obstruction.
The patient
26-year-old woman, 62 kg, at 37 weeks; anterior mediastinal mass found 2 weeks ago, probably lymphoma; no tissue diagnosis yet.
Breathless lying flat, sleeps on three pillows; facial swelling and distended neck veins.
No regular drugs. Planned caesarean delivery before oncology treatment.
Vitals (sitting): BP 112/70, HR 104, SpO2 96% on air, RR 22.
The examiner asks
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Consider
What are your concerns?
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- A 26-year-old at 37 weeks with an undiagnosed anterior mediastinal mass, for planned caesarean. Patient
- Term pregnancy adds caval compression, small FRC and a difficult airway to her mass.
- Orthopnoea warns that her airway may collapse at induction, possibly beyond any tube. Disease
- Facial swelling and full neck veins mean superior vena cava obstruction.
Prepare
How will you assess her?
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- Exactly which positions worsen or ease her breathing, and any faintness lying back. (Disease)
- CT of trachea and chest: over 50% tracheal compression marks high risk.
- Echo for pericardial effusion and compression of her heart or great vessels.
- Can tissue come from somewhere under local anaesthesia, like a neck node or effusion?
Prepare
How do you prepare for the caesarean?
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- Joint plan: obstetrics, thoracic surgery, oncology, cardiac anaesthesia, ICU and neonates. Patient
- Rigid bronchoscope and a surgeon able to use it in the room from the start. Airway
- A cannula in her leg as well as her arm, because her SVC is obstructed. Disease
- Femoral cannulas or wires placed under local first, so ECMO can start fast; bypass 'standby' alone is too slow.
Plan
What is your anaesthetic plan?
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- No general if possible: low-dose sequential CSE, or an epidural titrated slowly to T4. Disease
- Semi-sitting in her best position, with left uterine displacement; she is never laid flat. Patient
- Gradual onset keeps the fall in venous return slow. Disease
- No sedation that depresses her breathing; nasal oxygen throughout. Airway
- Neonatal team present; HDU after, since adults often obstruct in recovery. After surgery
Crisis
As the block rises she becomes stridulous and agitated; SpO2 86%, BP 88/50, HR 128, and the wound bleeds heavily. What do you do?
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- Sit her further up or turn her to her best position: that's the first rescue. (Crisis)
- 100% oxygen; she keeps breathing on her own, no relaxant.
- Obstetrician delivers now; emptying the uterus relieves her caval compression.
- Persisting obstruction: the surgeon passes a rigid bronchoscope beyond the narrowing.
- Fluid and blood through the leg cannula; arm infusions may not reach her heart.
- If she arrests: CPR with uterine displacement, deliver now; ECMO only via femoral access placed beforehand.
Fatal mistakes
- Supine general anaesthesia with a muscle relaxant.
- Venous access only in the arms with SVC obstruction.
- No planned rescue position before starting.
Checked against: Miller 10e · Barash 9e
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