Airway Fire Protocol in Laser Surgery

Notes for MD Anaesthesiology Examination

1. Introduction

2. The Fire Triad (Fire Tetrahedron)

Key fact: A PVC ETT will ignite in as little as 25% O2. Once ignited, it produces a "blowtorch" effect - an intensely burning jet of flame directed down the airway, producing toxic combustion debris.

3. Types of Lasers Used in Airway Surgery

CO2 laser: risk increases with continuous lasing >5 seconds (risk ×72) and lasing charred tissue (risk ×98). Every 10% increase in FiO2 above 60% raises fire risk ×2.3 with KTP laser.

4. Prevention of Airway Fire - The Anaesthesiologist's Role

4a. Pre-operative / Time-Out

• Discuss fire risk explicitly during surgical time-out with the entire team
• Assign roles: who stops laser, who removes ETT, who pours saline
• Post laser warning signs on OR doors
• Ensure wavelength-appropriate eye protection for all personnel (including patient)
• Have water/saline in a 60 mL syringe and basin immediately available at the field

4b. ETT Selection for Laser Surgery

Wrapping conventional ETTs with metallic foil tape is obsolete and not FDA-approved - the tape can break/unravel, the adhesive backing can ignite, and it may reflect laser onto non-targeted tissue.

4c. ETT Cuff Management

• Fill both cuffs with saline (not air) - water absorbs laser energy and resists ignition
• Add methylene blue dye to saline - acts as a visible indicator if the cuff is perforated by the laser (blue-stained fluid appears in the field)
• Double-cuffed laser tubes offer added protection: if proximal cuff is perforated, distal cuff continues to protect
• Position ETT cuff sufficiently deep below the vocal cords so it is away from the operative field

4d. Gas Management

• Keep FiO2 as low as clinically feasible - target FiO2 <0.3 (30%) if tolerated
• Avoid nitrous oxide entirely - N2O is an oxidising agent that actively supports combustion
• Use air as the carrier gas - many patients tolerate FiO2 of 21%
• Confirm FiO2 <0.3 on end-tidal gas analyser before surgeon activates laser (may require several minutes to dilute O2 at current fresh gas flow)
• Use TIVA (Total IV Anaesthesia) with propofol infusion - avoids volatile agents and N2O

4e. Laser Technique Precautions

• Surgeon should use pulsed lasing mode at minimum power
• Laser must be in STANDBY mode when not actively in use (not fired indiscriminately)
• Surgeon must give the anaesthesiologist adequate notice before activating laser (to confirm FiO2)
• Place saline-saturated pledgets/cottonoids around the ETT and adjacent tissue to limit ignition
• Avoid lasing adipose or charred tissue (highest fire risk)
• Limit continuous lasing duration to under 5 seconds per burst

5. Alternative Ventilation Strategies (Avoiding ETT Altogether)

6. Recognition of Airway Fire - Early Warning Signs

• Visible flame or flash in the operative field
• Unusual sound - a "pop" or "snap"
• Unusual odour or smoke
• Unexpected heat sensation felt by surgeon
• Unexpected movement or discolouration of breathing circuit or surgical drapes
• Unexpected patient movement
• Drop in SpO2 or sudden change in ventilator parameters

7. Airway Fire Protocol - Immediate Management

ASA Algorithm / Standard Protocol (Morgan & Mikhail Table 37-3):

• Cease all ventilation immediately
• Remove the ETT from the airway

• Turn off oxygen at the anaesthesia machine
• Disconnect the breathing circuit from the machine
• Stop N2O and all anaesthetic gas delivery

• Remove the burning ETT from the airway
• Remove all flammable materials: sponges, pledgets, gauze
• Submerge the removed ETT in water/saline to extinguish it

• Pour saline or water directly into the trachea to extinguish residual fire
• This addresses any residual burning tissue/charring within the airway

• Reventilate with face mask once fire confirmed extinguished
• Avoid supplemental oxygen initially if clinically possible
• Reintubate when airway control is regained, before oedema develops
• Reintubation should ideally be coordinated with bronchoscopy

• Perform bronchoscopy to:
  • Confirm fire is extinguished
  • Assess extent of thermal/inhalation injury
  • Remove all foreign body fragments (ETT debris, ash, sponge pieces)
  • Examine the entire airway including distal bronchi
• Serial chest X-rays
• Arterial blood gases (ABG) monitoring
• Consider bronchial lavage and corticosteroids for inhalation injury

Quick Memory Aid: "STOP, DROP, POUR, SCOPE"

• STOP ventilation and laser
• DROP (remove) the ETT and all flammable materials
• POUR saline into the airway
• SCOPE (bronchoscopy) to assess damage

8. Post-Fire Management

• Transfer to ICU for monitoring
• Monitor for:
  • Acute airway oedema (may require prolonged intubation or tracheostomy)
  • Chemical/thermal tracheobronchitis
  • ARDS from inhalation injury
  • Pneumonia (secondary to retained debris)
  • Late tracheal stenosis (can develop weeks to months later)
• IV corticosteroids (dexamethasone) to reduce airway inflammation
• Consider humidified oxygen and bronchodilators
• Nebulised N-acetylcysteine for mucosal protection
• Notify medicolegal and report the incident

9. Special Considerations

ETT Fire with Difficult Airway

Paediatric Patients

• Smaller airways = smaller calibre ETTs with thinner walls = ignite faster
• Laser-compatible ETTs may not be available in very small sizes (Nd:YAG-compatible tubes not available in half sizes)
• HFJV or intermittent apnoea techniques often preferred in children
• Papillomatosis (recurrent respiratory papillomatosis, RRP) is the most common indication for laser airway surgery in children

Tracheostomy

• High-risk scenario for airway fire even without laser: the electrocautery/diathermy is used in proximity to the trachea while the patient is receiving supplemental O2 via ETT
• Should reduce FiO2 before tracheal incision
• Protocol remains the same

10. Summary Table - Prevention vs Management

Key Exam Points to Remember

1. Fire triad: Fuel + Oxidiser + Ignition source. All three must be present.
2. PVC ETT ignites at 25% O2 - it is never truly safe in laser surgery.
3. No ETT is completely laser-proof - precautions reduce but never eliminate risk.
4. Methylene blue in cuff saline = visual indicator of cuff puncture.
5. N2O is an oxidiser - absolutely contraindicated in laser airway surgery.
6. First step in airway fire = Stop ventilation AND remove ETT simultaneously.
7. Pour saline into the airway - do not use CO2 fire extinguisher inside the airway.
8. Bronchoscopy is mandatory after every airway fire to remove debris and assess injury.
9. Continuous lasing >5 sec increases fire risk ×72 (Barash 9e).
10. ASA Practice Advisory on Operating Room Fires is the authoritative guideline.

What's Inside (10 Slides)