Anaesthesia for hemimandibulectomy

1. Preoperative assessment

• Mouth opening, Mallampati grade, mandibular protrusion, neck movement, dentition, nasal patency.
• Look for tumour-related distortion, trismus, bleeding, infection, tongue displacement, dysphagia, stridor, prior radiotherapy, and previous airway surgery.
• Review CT/MRI and, where indicated, flexible nasendoscopy with the surgical team.
• Anticipate difficult mask ventilation, laryngoscopy and intubation. Previous radiotherapy may cause fibrosis and distorted airway anatomy.

• Common comorbidities include smoking-related COPD, coronary disease, hypertension, diabetes, alcohol dependence, malnutrition and anaemia.
• Check CBC, coagulation, renal function, electrolytes, glucose, ECG and group-and-crossmatch. Correct anaemia, dehydration, electrolyte disturbance and malnutrition where feasible.
• Establish the reconstruction plan: radial forearm, fibula, scapular or anterolateral thigh flap. Avoid arterial/IV access in a proposed radial-forearm donor limb.
• Discuss the airway and extubation/tracheostomy plan jointly with the surgeon before induction.

2. Airway plan

Usual options

• Maintain spontaneous ventilation until the airway is secured if loss of the airway is a realistic concern.
• Use a reinforced, appropriately secured tube because the head and neck are inaccessible after draping.
• Nasal intubation is usually useful for intraoral access but is contraindicated or unsuitable with skull-base fracture, major nasal pathology, coagulopathy, or tumour involvement of the nasal route.
• Confirm tube position carefully after positioning and again after surgical manipulation.

3. Intraoperative conduct

Monitoring and access

• Standard ASA monitoring plus temperature and neuromuscular monitoring.
• Arterial line is usually appropriate for major resection/reconstruction: beat-to-beat blood pressure, blood gases, haemoglobin, glucose and lactate.
• At least two wide-bore IV cannulae.
• Urinary catheter for long surgery and fluid-output assessment.
• Central venous access only if necessary. Discuss the site with the surgeon because neck vessels may be required for dissection or microvascular anastomosis. Femoral or antecubital access can be alternatives.
• Verify all lines after arms are tucked and before draping.

Maintenance of anaesthesia

• General anaesthesia with a volatile agent or TIVA is suitable.
• Avoid prolonged hypotension, hypoxaemia, hypercarbia, hypothermia and severe anaemia, particularly during microvascular flap reconstruction.
• Use short-acting agents where possible to facilitate postoperative neurological and airway assessment.
• Use careful, quantitative neuromuscular monitoring and ensure full reversal before extubation if extubation is planned.
• If surgical nerve monitoring is planned, coordinate neuromuscular blockade with the surgeon.

Blood loss and fluids

• Major hemimandibulectomy can cause substantial bleeding, especially with neck dissection and flap harvest. Activate a blood-management plan and have blood products immediately available.
• Use balanced crystalloid in a goal-directed manner, replace blood loss promptly, and monitor serial Hb/ABG/lactate.
• Avoid both hypovolaemia and excessive crystalloid. Fluid overload promotes head and neck/flap oedema and can threaten airway and flap inset.
• Maintain normothermia with forced-air warming and warmed fluids. Hypothermia-related vasoconstriction can impair free-flap perfusion (Morgan and Mikhail's Clinical Anesthesiology, 7e, p. 1479).
• Treat clinically significant hypotension first by excluding bleeding, correcting volume deficit and optimising anaesthetic depth. Vasopressors may be used judiciously when required to maintain systemic perfusion, rather than allowing sustained hypotension.

Free-flap considerations

• Communicate closely at the time of microvascular anastomosis.
• Maintain normal temperature, oxygenation, normocapnia, adequate haemoglobin and perfusion pressure.
• Avoid mechanical compression or inappropriate positioning of the pedicle.
• Check that BP cuffs, lines and positioning do not compromise the donor limb or flap circulation.

4. Analgesia and PONV prophylaxis

• Paracetamol.
• NSAID/COX-2 inhibitor if not contraindicated and acceptable to the surgical team.
• Opioid titration or PCA when appropriate.
• Consider low-dose ketamine, dexmedetomidine or lidocaine infusion in selected patients to reduce opioid needs.
• Local infiltration or regional analgesia may be used when compatible with operative anatomy and flap monitoring.

5. Emergence and postoperative airway management

Consider elective tracheostomy or continued intubation if:

• Large oral cavity/floor-of-mouth resection.
• Bulky free flap or expected major oedema.
• Bilateral neck dissection.
• Difficult primary airway.
• Prolonged surgery, high fluid requirement, major transfusion, persistent bleeding risk.
• Tongue-base involvement, poor pulmonary reserve, or inability to protect the airway.

• Fully awake and cooperative.
• Full neuromuscular reversal.
• Adequate oxygenation/ventilation.
• Minimal airway oedema and bleeding.
• Reliable airway access if reintubation is required.
• Senior anaesthetist and surgeon agree that extubation is safe.

• Airway patency, neck swelling/haematoma, bleeding and aspiration.
• Flap colour, capillary refill, temperature, Doppler signal and venous congestion according to local flap protocol.
• Haemoglobin, coagulation, glucose, temperature and urine output.
• Respiratory complications, delirium, pain and nausea.

Short exam-style summary