Microlaryngoscopy and laser airway surgery

Surgical approach

Patient supine; head on ring; neck extension (“sniffing”/Boyce position) to align oral–pharyngeal–laryngeal axes
Suspension microlaryngoscopy: rigid laryngoscope inserted transorally and suspended on a stand; microscope/endoscope used for magnification
- Procedures: biopsy, excision of polyps/nodules, papillomatosis debulking, cordectomy, dilation, subglottic stenosis work, foreign body removal
Laser airway surgery: laser delivered via micromanipulator (CO₂) or fibre (e.g. KTP) to ablate/cut lesions
- Laser safety: eye protection, warning signs, smoke evacuation, wet swabs around laryngoscope, minimise oxidiser concentration
Shared airway: surgeon requires unobstructed view of glottis/subglottis; may request intermittent apnoea, jet ventilation, or small/laser tube

Anaesthetic management

Type of anaesthesia: General anaesthesia with controlled ventilation or tubeless technique (apnoea/jet/spontaneous) depending on lesion and surgeon preference
Airway device options: laser-resistant ETT (cuffed), microlaryngeal tube (MLT), tubeless (THRIVE, jet ventilation, intermittent apnoea)
Typical duration: 20–90 minutes (can be longer for extensive papillomatosis/stenosis work)
Pain: usually mild–moderate; main issues are airway irritation, coughing, laryngospasm, sore throat; consider opioid-sparing to aid smooth emergence
Key priorities: oxygenation/ventilation with shared airway, immobility, suppression of airway reflexes, fire prevention, and a rehearsed airway rescue plan

Indications and patient factors

Common indications: vocal cord polyps/nodules, Reinke’s oedema, papillomatosis, leukoplakia/dysplasia, early glottic cancer, subglottic stenosis, granuloma, foreign body
Symptoms suggesting difficult/critical airway: stridor (inspiratory/biphasic), dyspnoea at rest, voice change, inability to lie flat, previous radiotherapy, prior airway surgery
Comorbidity considerations: OSA/obesity (airway obstruction), COPD/asthma (air trapping with jet ventilation), reflux (laryngeal irritation), anticoagulation (bleeding obscures view/aspiration)
Pre-op assessment: flexible nasendoscopy findings if available; imaging (CT) for stenosis/tumour; baseline voice/airway symptoms; previous anaesthetic records

Pre-operative planning and communication

Agree with surgeon: lesion location (supraglottic/glottic/subglottic/tracheal), need for laser, need for tubeless field, and rescue strategy (including emergency tracheostomy/cricothyrotomy)
Discuss ventilation strategy: MLT/laser tube vs jet vs THRIVE vs intermittent apnoea; define triggers for stopping surgery and re-establishing ventilation
Prepare difficult airway equipment: videolaryngoscope, fibreoptic scope, bougies, smaller tubes, front-of-neck access kit; ensure ENT tracheostomy set immediately available
Laser checklist: laser sign, key control, eye protection for all, wet swabs, smoke evacuation, appropriate ETT, lowest feasible FiO₂, avoid N₂O

Airway/ventilation techniques (pros/cons)

Microlaryngeal tube (MLT) (e.g. 5.0–6.0 ID, longer): good ventilation and protection from blood/debris; still obstructs surgical view; tube movement can hinder precision
- Useful when laser not used or when surgeon accepts tube in field
Laser-resistant ETT (cuffed): reduces ignition risk but not fire-proof; cuff can be filled with saline (often with dye) to detect rupture; use lowest FiO₂ and avoid N₂O
- Disadvantages: larger external diameter, reduced view, potential cuff injury/airway trauma
Intermittent apnoea: preoxygenate, apnoeic window for surgery, then re-ventilate; excellent view; simple; limited by desaturation/hypercapnia and repeated instrumentation
THRIVE (high-flow nasal oxygen): extends apnoea time and improves oxygenation; CO₂ rises progressively; less reliable in severe obstruction; fire risk if laser near oxygen plume—must coordinate and minimise FiO₂/flow as appropriate
- Monitor: continuous SpO₂; consider transcutaneous CO₂ or frequent ETCO₂ surrogates when ventilation resumes
Jet ventilation (supraglottic/infraglottic/subglottic): tubeless field; requires expertise; risks include barotrauma, pneumothorax, subcutaneous emphysema, inadequate exhalation/air trapping, aspiration of blood/debris
- Contraindications/relative: severe distal obstruction, poor egress (stenosis), bullous lung disease, severe COPD, active lower airway pathology
- Monitoring: chest movement, SpO₂, airway pressure alarms (if available), careful observation for surgical emphysema; ETCO₂ may be unreliable
Spontaneous ventilation with TIVA/volatile: sometimes used for dynamic lesions; risk of coughing/laryngospasm and movement; may be useful when maintaining tone is desired (selected cases)

Anaesthetic technique

Induction: IV induction common (propofol ± opioid); consider inhalational induction if critical obstruction/stridor and concern about losing airway tone
- If critical obstruction: maintain spontaneous ventilation until ability to ventilate confirmed; have ENT present and front-of-neck access plan
Maintenance: TIVA (propofol/remifentanil) often preferred for immobility, rapid wake-up, reduced airway reactivity, and stable conditions during tubeless phases
- Volatile is acceptable if airway secured and no long apnoeic phases; beware theatre pollution if frequent circuit disconnections
Muscle relaxation: commonly used for tubed techniques and intermittent apnoea; avoid if surgeon requests spontaneous ventilation; ensure full reversal before extubation
Topicalisation: lidocaine to larynx/trachea can reduce reflexes; keep within safe dose (consider all sources)
Analgesia: paracetamol ± NSAID (if appropriate); small opioid doses often sufficient; consider dexamethasone for PONV and airway oedema
Emergence: aim for smooth, non-coughing wake-up to avoid bleeding/airway trauma; consider lidocaine, remifentanil washout strategy, and extubation plan (deep vs awake depending on risk)
- High-risk airway oedema/bleeding/obstruction: extubate fully awake with ENT present; consider staged extubation or post-op HDU/ICU

Laser-specific considerations

Fire triangle: ignition source (laser), oxidiser (O₂/N₂O), fuel (ETT, swabs, drapes, airway secretions)
Oxidiser control: use the lowest FiO₂ compatible with safe oxygenation; avoid N₂O (supports combustion and expands cuffs/bowel gas)
Tube/cuff: use laser-resistant tube when appropriate; fill cuff with saline (often tinted) and protect with wet pledgets; keep cuff below cords if possible
Gas leaks: minimise leaks around tube; avoid oxygen pooling in pharynx; coordinate with surgeon before laser activation
Smoke plume: use smoke evacuation; consider staff exposure and visibility; plume contains particulates and potentially viral material (e.g. papillomatosis)

Management of airway fire

Immediate actions: stop laser; stop ventilation and disconnect circuit; turn off oxygen/air flows
Remove burning material: remove ETT (and any fragments) promptly; remove burning swabs/foreign material from airway
Extinguish: pour saline/water into airway if needed; then re-establish ventilation with air/lowest FiO₂ via mask or reintubation
Re-assess airway: rigid/fibreoptic bronchoscopy to assess thermal injury and remove debris; consider ICU, humidified oxygen, steroids, antibiotics per local policy
Escalate: if cannot ventilate/intubate—front-of-neck access; involve ENT immediately

Complications and post-operative care

Airway: laryngospasm, bronchospasm, airway oedema, bleeding/haematoma, aspiration of blood/debris, dental/lip trauma from suspension laryngoscope
Ventilation strategy complications: hypercapnia (apnoea/THRIVE), barotrauma/pneumothorax (jet), gastric insufflation/aspiration (jet), tube displacement
Laser: airway fire, thermal injury, eye injury, plume exposure
Post-op: observe for stridor/respiratory distress; consider nebulised adrenaline, steroids, humidification; low threshold for re-examination and ICU if concern

You are asked to anaesthetise a patient for microlaryngoscopy and CO₂ laser excision of a vocal cord lesion. What are your main anaesthetic concerns?

Structure around shared airway, fire risk, and safe emergence.

Shared airway: maintaining oxygenation/ventilation while providing an unobstructed surgical field; anticipate repeated airway manipulation
Airway fire risk: laser + oxidiser + fuel; plan to minimise FiO₂, avoid N₂O, use appropriate tube/cuff strategy and wet swabs
Need for immobility and suppression of airway reflexes (coughing/laryngospasm) to allow precise laser work
Airway rescue: plan for loss of airway, bleeding, laryngospasm, tube displacement; ensure ENT and FONA readiness
Post-op obstruction risks: oedema, bleeding, laryngospasm; plan extubation and post-op observation/ICU if indicated

Describe how you would reduce the risk of airway fire during laser airway surgery.

Address each side of the fire triangle: oxidiser, fuel, ignition source.

Oxidiser: use lowest FiO₂ compatible with safe SpO₂; avoid N₂O; minimise oxygen pooling (avoid large leaks, consider air/oxygen blend)
Fuel: use laser-resistant ETT when appropriate; saline-filled cuff (often dyed); protect cuff/tube with wet pledgets; keep surgical field free of dry swabs
Ignition control: clear communication—laser only on when ready; standby mode when not in use; laser safety checks and trained operator
Environment: eye protection for all; warning signs; smoke evacuation; avoid flammable prep solutions pooling

What is your immediate management if an endotracheal tube ignites during laser surgery?

Time-critical drill; prioritise stopping combustion and re-establishing oxygenation.

Stop laser immediately; stop ventilation; disconnect circuit; turn off all gas flows
Remove ETT promptly (and any burning fragments); remove burning swabs/foreign material
Flood airway with saline/water if needed to extinguish residual fire
Re-oxygenate/ventilate with air then lowest FiO₂; reintubate as required (consider smaller tube) or mask ventilate
Bronchoscopy to assess injury and remove debris; plan ICU, humidification, steroids/analgesia; document and incident report

Compare options for ventilation during microlaryngoscopy: MLT/laser tube vs intermittent apnoea vs jet ventilation vs THRIVE.

Compare in terms of view, oxygenation/CO₂ control, aspiration protection, and complications.

MLT/laser tube: reliable ventilation and airway protection; tube obstructs view and can be struck by laser; fire risk remains
Intermittent apnoea: excellent view; simple; limited by desaturation/hypercapnia; repeated instrumentation and potential trauma
Jet ventilation: tubeless field and continuous oxygenation; risks barotrauma, air trapping, pneumothorax, surgical emphysema; CO₂ monitoring difficult; aspiration risk
THRIVE: prolongs apnoea and improves oxygenation; CO₂ rises; less effective in severe obstruction; must manage oxygen plume/fire risk with laser

A patient has stridor and a suspected laryngeal tumour for microlaryngoscopy and biopsy. How would you approach induction and securing the airway?

Goal: avoid converting partial obstruction into complete obstruction; maintain oxygenation and a rescue route.

Pre-op: review nasendoscopy/imaging; assess severity (resting stridor, inability to lie flat); discuss with ENT and plan for emergency tracheostomy
Induction strategy: consider maintaining spontaneous ventilation (e.g. inhalational or carefully titrated IV) until ability to ventilate is confirmed
Airway options: awake fibreoptic intubation may be difficult if lesion bleeds/obstructs; consider awake tracheostomy in extreme cases; have smaller tubes and alternative devices ready
Avoid: heavy sedation without a plan; paralysis before confirming mask ventilation in a precarious airway
Rescue: clear triggers for abandoning attempts and proceeding to FONA; ensure skilled help present

How would you monitor ventilation during jet ventilation or prolonged apnoeic techniques?

ETCO₂ may be unreliable; use multiple modalities and clinical assessment.

Oxygenation: continuous pulse oximetry; consider arterial line if high risk/long case
Ventilation: observe chest movement; listen for exhalation; watch for air trapping; consider transcutaneous CO₂ monitoring
CO₂: intermittent capnography when circuit reconnected; arterial blood gases if prolonged/unstable
Complications: monitor for surgical emphysema, pneumothorax (sudden desaturation, hypotension, increased airway pressure if measurable)

What are the advantages of TIVA for microlaryngoscopy and laser airway surgery?

Think: operating conditions, rapid control, and compatibility with tubeless phases.

Stable depth with minimal movement/coughing (propofol + remifentanil commonly used)
Rapid wake-up and titratability, useful when alternating between apnoea and ventilation
Less theatre pollution during frequent circuit disconnections compared with volatile techniques
Potentially reduced PONV with propofol-based techniques

List complications specific to suspension microlaryngoscopy and how you would mitigate them.

Mainly mechanical trauma and airway events.

Dental/lip/tongue trauma: careful insertion, dental guards, padding, check pressure points; document pre-existing dental issues
Tongue oedema/neuropraxia from prolonged suspension: minimise duration, intermittent release if long case, monitor post-op swelling
Laryngospasm/bronchospasm: adequate depth, topical lidocaine, smooth emergence; treat promptly (CPAP, propofol, suxamethonium if needed)
Bleeding/aspiration: secure airway when appropriate; suction available; consider throat pack with clear documentation and removal

How would you plan extubation after laser surgery on the vocal cords?

Balance smoothness vs safety; anticipate oedema and bleeding.

Assess risk: extent of surgery, bleeding, airway swelling, pre-op stridor, difficult airway, comorbid OSA/obesity
Smooth emergence: minimise coughing (consider lidocaine, careful opioid strategy); ensure full reversal and adequate ventilation
High-risk: extubate fully awake with ENT immediately available; consider staged extubation (airway exchange catheter) or post-op intubation/ICU
Post-op: monitor for stridor; treat with humidified oxygen, nebulised adrenaline, steroids; low threshold to re-scope/reintubate