Obese patient with untreated obstructive sleep apnoea for urgent cholecystectomy
A 52-year-old man (BMI 44 kg/m2, neck circumference 46 cm) presents with a 3-day history of acute cholecystitis and is booked for urgent laparoscopic cholecystectomy. He has obstructive sleep apnoea with a documented apnoea-hypopnoea index of 42 events per hour; CPAP was prescribed two years ago but he stopped using it eight months ago. His STOP-BANG score is 6. He also has type 2 diabetes (HbA1c 8.9%) and takes oxycodone 10 mg twice daily for chronic back pain. He reports loud snoring, witnessed apnoeas and morning headaches. Airway examination shows a Mallampati 3 view, mouth opening of 3.5 cm, a short thyromental distance and full dentition. Blood pressure is 156/88 mmHg, SpO2 93% on room air, and the chest radiograph is clear. The surgeon requests pneumoperitoneum at 15 mmHg with reverse Trendelenburg positioning. The hospital has a post-anaesthesia care unit and a step-down unit, but no intensive care bed is currently free.
1. How would you plan induction of anaesthesia and airway management, and why?
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The dominant risk here is the airway: BMI 44, Mallampati 3, mouth opening 3.5 cm, short thyromental distance, dentition and a baseline SpO2 of 93% all predict difficult mask ventilation and difficult intubation, and the low baseline oxygen reserve means desaturation will be rapid. A 'routine' induction with a paralysing dose before confirming ventilatability is unsafe.
Plan:
- Position ramped (ear-to-sternal notch) and preoxygenate with CPAP 10 cmH2O for 3-5 minutes plus high-flow nasal oxygen 15 L/min for apnoeic oxygenation.
- Check equipment and personnel before induction: two working suction units, videolaryngoscope with both standard and hyperangulated blades, second-generation supraglottic airway, flexible scope and a front-of-neck access kit, with a second anaesthetist present.
- Rapid sequence induction using propofol dosed on adjusted body weight (about 1.5-2 mg/kg) and rocuronium 1.2 mg/kg, with gentle mask ventilation permitted after loss of consciousness (the aspiration risk from cholecystitis is moderate and mask ventilation is likely to be difficult, so a brief gentle attempt is acceptable).
- First intubation attempt with videolaryngoscopy, maximum three attempts with optimisation between each, then a supraglottic airway and, if ventilation fails, a declared CICO plan.
Because he has a full stomach and difficult airway, awake videolaryngoscopy is a defensible alternative if the airway examination worsens on the day.
2. Outline your intraoperative anaesthetic and analgesic strategy, naming agents and doses where relevant, and justify each choice.
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Every element aims to minimise the opioid load, because opioid-induced respiratory depression superimposed on untreated OSA is the main cause of postoperative harm.
- Maintenance: sevoflurane 0.9-1.0 MAC in an oxygen-air mix, or propofol TIVA; keep pneumoperitoneum at 10-12 mmHg rather than 15 if surgical exposure allows, and use PEEP 8-10 cmH2O with reverse Trendelenburg to protect functional residual capacity.
- Adjuncts: dexmedetomidine 0.3-0.5 mcg/kg/h (expect bradycardia), lidocaine 1.5 mg/kg before induction, ketamine 0.3 mg/kg at induction, dexamethasone 8 mg and ondansetron 4 mg for nausea, and ketorolac 15-30 mg if renal function is acceptable.
- Regional: surgeon-infiltrated port-site local anaesthetic or a bilateral transversus abdominis plane block with 0.25% bupivacaine, 20 mL per side, to reduce the opioid requirement substantially.
- Neuromuscular block: quantitative train-of-four monitoring throughout; reverse with sugammadex 2 mg/kg and document a train-of-four ratio of at least 0.9 before extubation. Sugammadex is preferable to neostigmine here because it avoids cholinergic side effects and gives reliable, rapid recovery.
- Extubate awake, sitting up, obeying commands, with tidal volumes at least 5 mL/kg.
A remifentanil infusion would give smooth conditions but provides no opioid sparing once stopped; if used, it must be paired with the multimodal regimen above and not continued as a postoperative infusion.
3. Where should this patient recover, and what criteria would you use before extubation and before leaving the recovery area?
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This patient is not an ambulatory or ward-level candidate. He has untreated severe OSA, is opioid-tolerant with a high baseline requirement, and has no ICU bed available, so the correct disposition is a step-down or high-dependency bed with continuous pulse oximetry, capnography where available, and immediate access to CPAP and a re-intubation trolley.
Extubation criteria: awake and obeying commands, train-of-four ratio at least 0.9, spontaneous tidal volume at least 5 mL/kg with respiratory rate below 20, stable haemodynamics with systolic pressure within 20% of baseline, and analgesia adequate at rest without a background opioid infusion. Extubate in the sitting position and apply CPAP immediately after extubation, since his pharyngeal tone and functional residual capacity will both be poor.
Criteria before transfer out of recovery: Aldrete score of 9 or higher, sustained SpO2 above 92% on room air or his baseline oxygen, no apnoeic episodes or desaturations below 90% for at least 60 minutes, pain controlled with oral or nurse-administered bolus opioids only, and no sedation score deeper than 2 on the POSS scale.
Avoid continuous or background opioid infusions, avoid sedative-hypnotics for agitation, restart his CPAP or provide a new machine, and organise a sleep study and CPAP re-titration before discharge.