Airway Fire in the Operating Room - Prevention and Management

Quick Answer

Immediate Management (Critical First 60 Seconds):

1. Simultaneously: Remove all airway devices (ETT, LMA, nasal tube, etc.)
2. Disconnect oxygen source - flood circuit with air
3. Pour sterile saline into airway (300-500 mL if available)
4. Call for help - team fire drill protocol
5. Stop surgery - surgeon remove all ignition sources
6. Re-establish ventilation once fire confirmed extinguished

Key Prevention Principles:

• Avoid nitrous oxide in airway/laser surgery (minimum alveolar concentration for combustion 20%)
• FiO2 ≤30% for airway surgery when possible
• Use cuff pressure monitoring (EAMS system or regular checks)
• Maintain cuff pressure >20 cmH2O to prevent oxygen diffusion
• Use saline-filled cuffs when appropriate
• Laser-resistant ETT for head/neck laser surgery

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Indigenous Health Considerations

Airway fire and surgical safety concerns present unique challenges for Aboriginal, Torres Strait Islander, and Māori communities in Australia and New Zealand. For Aboriginal and Torres Strait Islander patients, higher rates of smoking (approximately 37% in remote communities) increase tracheal oxygen concentration during sedation and airway procedures, elevating fire risk during high-dependency surgical cases. Remote health facilities often lack comprehensive fire safety protocols and advanced airway equipment for fire emergencies, requiring early recognition and transfer protocols.

Cultural safety considerations are paramount when managing surgical emergencies in Indigenous populations. Many Aboriginal patients exhibit heightened anxiety in metropolitan hospital settings due to historical medical mistrust and institutional racism. During crisis situations like airway fire, family communication must involve Aboriginal Liaison Officers and culturally appropriate interpretation services where language barriers exist. Patient decision-making often involves extended kinship groups, and consent discussions must accommodate collective decision-making processes.

Māori health considerations include higher rates of obesity and obstructive sleep apnea, which can complicate airway management and fire risk assessment. Whānau involvement in surgical consent and crisis management follows principles of manaakitanga (hospitality and care) and whakawhanaungatanga (relationship-building). When surgical fires occur, Māori patients and families may require access to karakia (prayers) and spiritual support during crisis situations.

Remote and rural considerations are critical for both Aboriginal and Māori populations, where patients may present for emergency airway surgery at regional hospitals with limited anaesthetic expertise. RFDS transfer protocols must include airway fire management training for retrieval teams. Healthcare providers must engage with local Aboriginal Medical Services (AMS), Māori Health Workers, and community elders to develop culturally safe fire prevention protocols and emergency response procedures. Indigenous health workers should be involved in pre-operative safety briefings and crisis management planning.

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Clinical Overview

Definition and Classification

Operating room (OR) fire is defined as any uncontrolled combustion occurring within the operating theatre environment, with three essential components required: an oxidiser, a fuel, and an ignition source (the "fire triangle"). [1] Airway fire specifically refers to combustion within the patient's respiratory tract or involving airway devices (endotracheal tubes, laryngeal mask airways, nasal cannulae). [2]

Classification of OR Fires: [3]

• Type 1 (Surgical fire): Combustion at surgical site (drapes, hair, bowel gas)
• Type 2 (Airway fire): Combustion involving respiratory tract or breathing circuit
• Type 3 (Preparation/Recovery fire): Patient preparation or recovery area

Incidence and Epidemiology

OR fires occur in approximately 1 in 50,000 to 1 in 100,000 surgical procedures, though reporting is incomplete. [4,5] Airway fires represent 20-30% of all OR fires, with head and neck surgery accounting for the majority. [6] The incidence has declined with improved safety protocols but remains a significant concern, particularly during high-risk procedures.

High-Risk Procedures: [7,8]

• Head and neck surgery (25-30% of airway fires)
• Tonsillectomy/adenoidectomy
• Tracheostomy
• Laser airway surgery
• Oropharyngeal procedures with cautery
• Bronchoscopy with cautery or laser

Pathophysiology of Combustion in the Airway

The Fire Triangle in Anaesthesia: [9]

1. Oxidiser: Oxygen and/or nitrous oxide
2. Fuel: ETT materials (PVC, rubber), surgical drapes, tissue, hair, bowel gas (methane/hydrogen)
3. Ignition: Electrocautery, laser, heated probes, defibrillator

Critical Thresholds: [10,11]

• Oxygen concentration: Flammability increases exponentially >25% FiO2
• Nitrous oxide: Supports combustion at concentrations >20%
• PVC ETT ignition: Can occur at 34% oxygen concentration with cautery
• Silicone/red rubber ETT: Higher ignition temperature but still combustible
• Laser-resistant ETT: Metal foil or matte black surface protection

Mechanism of Airway Fire Propagation: [12] When ignition occurs in the presence of oxygen-enriched atmosphere within the airway:

1. Localised heating of ETT material
2. Decomposition releasing toxic gases (hydrogen chloride from PVC)
3. Flash fire spreading along oxygen column
4. Potential for tracheal mucosa thermal injury
5. Risk of distal embolisation of burning debris

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Prevention Strategies

ANZCA PS04(G) - Anaesthesia and Fire Risk Management

ANZCA Professional Document PS04(G) establishes minimum standards for fire safety in Australian and New Zealand operating theatres. [13,14]

Key Requirements:

• Pre-operative fire risk assessment documented
• Oxygen concentration minimisation protocols
• Nitrous oxide avoidance in high-risk cases
• Availability of saline for fire extinguishment
• Team fire drill protocols established

Risk Assessment and Stratification

Pre-Operative Fire Risk Checklist: [15]

Score 6-9: High-risk - Mandatory fire prevention protocol Score 3-5: Moderate-risk - Standard precautions enhanced

Oxygen Concentration Management

ANZCA Recommendations: [16,17]

1. Target FiO2 ≤30% for all head/neck surgery when safe
2. Room air ventilation for facial/dental surgery when possible
3. Titrated oxygen delivery via nasal cannula at lowest effective flow
4. Pre-oxygenation considerations: Use lowest effective FiO2, limit time

Safe FiO2 Targets by Procedure:

• Tonsillectomy: 21-25% (room air to minimal supplementation)
• Tracheostomy: 21-30% (higher only if desaturation)
• Head/neck flap: 25-30% balanced with tissue perfusion
• Laser laryngeal: 21% (room air mandatory when feasible)

Nitrous Oxide Avoidance

Scientific Basis: [18,19]

Nitrous oxide (N₂O) is an oxidising agent that:

• Lowers ignition temperature of fuels
• Increases combustion intensity
• Spreads flames rapidly
• Minimum alveolar concentration for combustion: 20%

ANZCA Guidelines mandate avoiding N₂O when:

• Open airway to atmosphere (face, oropharynx, trachea)
• Head and neck surgery with cautery
• Laser airway procedures
• Bowel surgery with cautery
• Tonsillectomy/adenoidectomy

Alternative Agents: [20]

• Air/oxygen mixture
• Total intravenous anaesthesia (TIVA)
• Volatile agents (sevoflurane, desflurane) with air carrier

Airway Device Selection and Management

Endotracheal Tube Selection: [21,22]

Cuff Pressure Management: [23,24]

Critical Importance: Oxygen diffuses across ETT cuff into trachea, creating oxygen-enriched pocket susceptible to ignition.

ANZCA Recommendations:

1. Maintain cuff pressure 20-30 cmH₂O (minimum 20 cmH₂O)
2. Use cuff pressure manometer every 30-60 minutes
3. Consider continuous monitoring (EAMS system) for high-risk cases
4. Saline-filled cuffs for laser cases (no oxygen diffusion)
5. Cuff deflation before cautery/laser application (when safe)

Saline-Filled Cuff Technique: [25]

• Remove all air from cuff via pilot balloon
• Inject 4-8 mL sterile saline (adult ETT)
• No oxygen diffusion across liquid barrier
• Visible indicator of cuff integrity

Surgical Draping and Preparation

Drape Configuration Protocol: [26,27]

1. Avoid oxygen pooling: Do not create "tenting" with drapes
2. Head drape configuration: Allow oxygen to dissipate
3. Adhesive drapes: Secure but allow air circulation
4. Tenting prevention: Use split sheets, avoid enclosed spaces
5. Hair management: Wet hair thoroughly, consider removal

Bowel Surgery Considerations: [28,29]

• Bowel gas composition: Methane (flammable), hydrogen (highly flammable), hydrogen sulfide
• Pre-operative bowel prep: Reduces gas volume
• N₂O avoidance: Prevents diffusion into bowel lumen
• Cautery precautions: Avoid contact with bowel gas

Team Communication and Fire Drills

WHO Surgical Safety Checklist - Fire Risk: [30,31]

Before every high-risk case:

1. Confirm fire risk assessment complete
2. Verify oxygen concentration strategy
3. Ensure saline available for extinguishment
4. Assign roles for fire emergency
5. Confirm evacuation pathway

Fire Drill Protocol: [32]

• Quarterly drills for all OR staff
• Scenario-based training (airway fire simulation)
• Role assignment clarity (surgeon, anaesthetist, scout nurse, circulating nurse)
• Communication hierarchy during crisis
• Debriefing and protocol review

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Recognition and Diagnosis

Early Warning Signs

Pre-ignition Indicators: [33]

• Acrid smell (burning PVC/rubber)
• Visible smoke from airway
• Unexpected patient movement or distress
• Change in ventilator pressures
• Discoloration of ETT

Active Airway Fire Signs: [34]

• Flames visible in oropharynx or at ETT connection
• Smoke from airway or breathing circuit
• Sudden loss of EtCO2 waveform
• Patient distress: Gasping, agitation, desaturation
• Audible sounds: Crackling, popping noises
• Equipment damage: Melted circuit components

Severity Grading

Airway Fire Severity Classification: [35]

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Acute Management

Immediate Response (First 60 Seconds)

STEP 1: Stop the Fire (All Actions Simultaneous) [36,37]

Anaesthetist Actions:

1. Disconnect oxygen source immediately
   • Remove circuit from patient
   • Turn off fresh gas flow
   • Flush machine with air
2. Remove airway device
   • Deflate ETT cuff if safe and feasible
   • Remove ETT/LMA/nasal cannula rapidly
   • Do NOT attempt to extinguish fire in situ

Surgeon Actions:

1. Remove ignition source
   • Stop cautery/laser immediately
   • Remove any heated instruments
   • Douse surgical site with saline
2. Remove drapes and fuel sources
   • Strip away burning/melted drapes
   • Wet any remaining fuel

STEP 2: Extinguishment [38,39]

1. Flood airway with sterile saline (300-500 mL if available)
   • Pour directly into oropharynx/trachea
   • Use largest available syringe or fluid bag
   • Continue until no smoke/flames visible
2. Maintain airway patency
   • Suction debris and fluid aggressively
   • Manual ventilation with 100% oxygen once fire out

STEP 3: Assess and Re-establish [40,41]

1. Visual inspection of airway
   • Direct laryngoscopy to assess damage
   • Look for ETT fragments, soot, debris
   • Assess vocal cord movement
2. Re-intubation when safe
   • Cricoid pressure if full stomach
   • Smaller ETT size may be required
   • Consider awake fibreoptic if difficult
3. Bronchoscopy indication
   • All Grade 2-4 fires
   • Any suspected distal debris
   • Persistent desaturation or respiratory distress

Post-Fire Algorithm

Immediate Post-Fire Assessment: [42,43]

Investigations:

• Chest X-ray: Look for pneumothorax, thermal injury signs
• CT chest: If suspected tracheal/bronchial injury
• ABG: COHb (carboxyhaemoglobin) if smoke inhalation
• Fibreoptic bronchoscopy: Mandatory for Grade 2-4 fires

Ventilation Strategy Post-Fire

Initial Ventilation Settings: [44,45]

1. FiO2 100% initially (titrate down as appropriate)
2. Protective lung ventilation:
   • Tidal volume 6-8 mL/kg IBW
   • Plateau pressure <30 cmH₂O
   • PEEP 5-10 cmH₂O
3. Bronchodilators: Salbutamol if bronchospasm
4. Humidification: Heated humidification essential

Airway Injury Patterns: [46,47]

• Supraglottic: Most common, oedema develops 6-24 hours
• Glottic: Vocal cord injury, potential airway obstruction
• Subglottic/tracheal: Life-threatening, requires ICU monitoring
• Bronchial: Thermal smoke inhalation, ARDS risk

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Complications and Sequelae

Immediate Complications

Airway Injury: [48,49]

• Thermal burns to supraglottic structures (75% of cases)
• Tracheal mucosal sloughing
• Airway oedema (peak at 12-24 hours)
• Risk of airway obstruction
• Laryngospasm from chemical irritation

Respiratory: [50]

• Smoke inhalation injury
• Chemical pneumonitis (HCl from PVC combustion)
• ARDS development
• Pneumothorax from barotrauma
• Bronchospasm

Systemic: [51,52]

• Carbon monoxide poisoning (COHb elevation)
• Cyanide toxicity (from combustion of nitrogen-containing materials)
• Hypoxic brain injury if prolonged desaturation
• Psychological trauma to patient and staff

Long-Term Sequelae

Chronic Complications: [53,54]

• Subglottic/tracheal stenosis (5-10% of significant injuries)
• Vocal cord dysfunction
• Chronic respiratory symptoms
• Post-traumatic stress disorder
• Airway reactivity

Surgical Sequelae: [55]

• Need for tracheostomy (temporary or permanent)
• Airway stenting
• Repeated bronchoscopies
• Reconstructive laryngeal surgery

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Special Considerations

Laser Airway Surgery

Laser-Specific Protocols: [56,57]

1. Laser-resistant ETT mandatory
   • Metal foil wrapped ETT
   • Specialised laser tubes (Sheridan, Xomed)
   • Verify laser compatibility (wavelength-specific)
2. FiO2 ≤30% (ideally 21%)
3. Saline-soaked pledgets around tube
4. Laser safety officer designated
5. Eye protection for all staff
6. Warning signs posted ("Laser in Use")

Laser ETT Failure Mode: [58]

• Laser strike on unprotected area
• Rapid heating of adjacent tissue
• Potential for airway ignition even with protected tube

Paediatric Considerations

Unique Risks in Children: [59,60]

1. Smaller airway diameter: Greater risk of obstruction from oedema
2. Higher oxygen consumption: May require higher FiO2, increasing risk
3. Tonsillectomy: Most common paediatric airway fire scenario
4. Uncuffed ETT use: Cannot use cuff pressure management

Paediatric Fire Prevention:

• FiO2 titrated to lowest safe level
• Venturi mask oxygen delivery (controlled concentration)
• Vigilant draping to prevent oxygen pooling
• Rapid sequence induction for tonsillectomy
• Liberal use of saline-soaked gauze

Pregnancy Considerations

Obstetric Fire Risks: [61,62]

• Foetal oxygen requirements: Higher FiO2 may be "required"
• Tonsillectomy in pregnancy: Rare but documented
• Emergency airway procedures: Time pressure may compromise safety
• Left lateral tilt: Can affect drape configuration and oxygen pooling

Management Principles:

• Balance maternal oxygenation with fire risk
• Prioritise maternal safety (foetal survival depends on maternal survival)
• Titrated oxygen rather than routine high FiO2
• Team communication about dual-patient risk

Emergency Surgery

Challenges in Emergency Cases: [63,64]

• Time pressure compromises safety checks
• Full stomach increases aspiration risk during ETT change
• Inexperienced teams (after-hours)
• Limited equipment availability

Mitigation Strategies:

• Use crisis checklists even in emergencies
• Brief team on fire risk even if brief
• Ensure saline immediately available
• Assign specific fire response roles

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Indigenous Health Considerations

Note: This section expands on the Quick Answer section above for comprehensive cultural safety training.

Aboriginal and Torres Strait Islander Health

Epidemiological Context: [65,66]

Aboriginal and Torres Strait Islander peoples experience disproportionate rates of smoking-related diseases, with 37% of remote Indigenous adults smoking daily compared to 12% of non-Indigenous Australians. This significantly impacts airway management:

• Higher baseline carboxyhaemoglobin: Chronic smoke exposure
• Increased airway reactivity: Chronic bronchitis, COPD
• Greater oxygen requirements: Pre-existing hypoxaemia
• Elevated fire risk: Tracheal oxygen concentration higher with nasal oxygen

Cultural Safety in Crisis Management: [67,68]

When airway fire occurs, healthcare providers must recognise that historical trauma affects how Indigenous families respond to medical emergencies:

1. Communication Barriers:

   • Many Aboriginal patients speak English as second or third language
   • Medical terminology and crisis explanations require translation
   • Aboriginal Liaison Officers essential for family communication
   • Allow time for family decision-making (collective consensus)

2. Trust and Engagement: [69]

   • Explain all procedures clearly before surgery
   • Acknowledge past negative experiences with healthcare system
   • Involve Aboriginal Health Workers in pre-operative planning
   • Maintain transparency during crisis situations

3. Remote/Rural Considerations: [70,71]

   • Regional hospitals serving Indigenous populations may lack:
     • Laser-resistant ETT inventory
     • Advanced airway fire management training
     • Fibreoptic bronchoscopy capability
   • Early recognition of limitations and transfer protocols essential
   • RFDS retrieval teams require airway fire management training

4. Kinship and Decision-Making: [72,73]

   • Surgical consent often involves extended family
   • Crisis decisions (re-intubation, tracheostomy) require family consultation
   • Sorry Business considerations if adverse outcomes occur
   • Access to traditional healers and cultural practices during recovery

Māori Health (Aotearoa New Zealand)

Māori Health Disparities: [74,75]

Māori experience significant health inequities in New Zealand, with higher rates of:

• Obesity (48% vs 29% non-Māori)
• Obstructive sleep apnoea
• Smoking (32% vs 13% non-Māori)

These factors increase anaesthetic complexity and fire risk during airway procedures.

Te Tiriti o Waitangi (Treaty of Waitangi) Obligations: [76,77]

Healthcare providers have treaty obligations to ensure:

• Partnership: Māori involvement in health service design
• Participation: Māori workforce in healthcare delivery
• Protection: Equity in health outcomes

Application to Airway Fire Management:

1. Whānau-Centred Care: [78]

   • Whānau (extended family) involvement in surgical planning
   • Karakia (prayers) before and after surgery
   • Māori Health Workers in multidisciplinary team
   • Cultural safety training for all OR staff

2. Communication Protocols: [79,80]

   • Te reo Māori interpreters when required
   • Understanding of non-verbal communication styles
   • Respect for tapu (sacred) and noa (common) concepts in healthcare
   • Whakawhanaungatanga (relationship-building) before procedures

3. Post-Crisis Support: [81,82]

   • Rongoā Māori (traditional healing) alongside Western medicine
   • Access to kaumatua (elders) for spiritual guidance
   • Whānau support during ICU admission if required
   • Trauma-informed care recognising historical health system trauma

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ANZCA Exam Focus

Written Examination (SAQ)

High-Yield Topics:

1. Fire triangle and anaesthetic modification
2. Nitrous oxide avoidance rationale (MAC for combustion, diffusion)
3. Cuff pressure management (why >20 cmH₂O, diffusion physics)
4. FiO2 targets for specific procedures (tonsilllectomy, tracheostomy)
5. Laser airway protocols (ETT selection, FiO2 limits, safety measures)
6. Bowel surgery fire prevention (N₂O avoidance, gas composition)

Common SAQ Scenarios:

Scenario 1: "A 45-year-old patient undergoing tonsillectomy under general anaesthesia experiences an airway fire. Describe your immediate management and subsequent investigation plan. (20 marks)"

Scenario 2: "A patient is scheduled for laser excision of vocal cord lesion. Describe your anaesthetic management to minimise fire risk. (15 marks)"

Viva Voce Examinations

Expected Viva Themes:

Theme 1: Fire Prevention Protocol

• "You're anaesthetising for head and neck surgery. How do you prevent an airway fire?"
  • Key points: Risk assessment, FiO2 minimisation, N₂O avoidance, cuff pressure

Theme 2: Crisis Management

• "The surgeon shouts 'Fire!' during tracheostomy. What are your immediate actions?"
  • Key points: Simultaneous disconnect oxygen/remove ETT, saline flood, team coordination

Theme 3: Post-Fire Care

• "Following an airway fire, what investigations and monitoring are required?"
  • Key points: Bronchoscopy, oedema monitoring, ICU admission criteria

Viva Scenario Example

Examiner: "You are anaesthetising a 35-year-old for laser debulking of laryngeal papillomas. How do you minimise fire risk?"

Candidate Response Framework:

1. Pre-operative:

   • "I would conduct a fire risk assessment and brief the team"
   • "Laser-resistant ETT mandatory - either specialised tube or foil-wrapped"
   • "Confirm laser wavelength compatibility"

2. Intra-operative Oxygen Strategy:

   • "Use room air or FiO2 ≤30% - lowest safe concentration"
   • "Avoid nitrous oxide completely"
   • "Consider TIVA to avoid volatile agents in high oxygen"

3. Airway Management:

   • "Saline-filled ETT cuff to prevent oxygen diffusion"
   • "Regular cuff pressure monitoring if air-filled"
   • "Saline-soaked pledgets around tube"

4. Team Coordination:

   • "Communication with surgeon about laser activation timing"
   • "Saline immediately available for extinguishment"
   • "Fire drill protocol agreed"

5. Monitoring:

   • "SpO2 monitoring with target 94-98% (not 100%)"
   • "End-tidal oxygen monitoring if available"
   • "Vigilance for early signs (smell, smoke)"

Examiner Follow-up: "The laser ignites the ETT. What do you do?"

Candidate: "Immediate simultaneous actions: disconnect oxygen source, remove the ETT, and pour saline into the airway. Stop the laser. Re-establish airway when safe with bronchoscopic assessment."

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Short Answer Questions

SAQ 1: Fire Prevention in Tonsillectomy

Question: (20 marks) A 28-year-old patient is scheduled for elective tonsillectomy under general anaesthesia.

a) Outline the fire risk assessment for this procedure. (5 marks)

b) Describe your strategy to minimise fire risk during this case. (10 marks)

c) The surgical team plans to use diathermy. What additional precautions are required? (5 marks)

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Model Answer:

a) Fire Risk Assessment (5 marks):

Risk scoring: 6-9/9 (High-risk category)

b) Fire Risk Minimisation Strategy (10 marks):

1. Oxygen Management (4 marks):

   • Use lowest effective FiO2 (target 21-30%)
   • Consider air/oxygen mixture rather than 100% O2
   • Pre-oxygenate with 100% then reduce to 30% before cautery
   • Avoid nitrous oxide (supports combustion, MAC 20%)

2. Airway Device Management (3 marks):

   • Use standard cuffed ETT (not uncuffed)
   • Maintain cuff pressure >20 cmH₂O (prevents O2 diffusion)
   • Check cuff pressure every 30 minutes
   • Consider saline-filled cuff for additional safety

3. Surgical Coordination (3 marks):

   • Communicate with surgeon about cautery timing
   • Ensure surgeon informs anaesthetist before each cautery use
   • Surgeon to use lowest effective power setting
   • Keep cautery tip clean (no tissue/debris build-up)

c) Electrocautery Precautions (5 marks):

1. Device Settings:

   • Lowest effective power (coagulation mode preferred over cut)
   • Clean tip before use
   • Short bursts rather than continuous application

2. Operational Protocol:

   • "Cautery warning" - surgeon announces intent
   • Reduce FiO2 to 21% if SpO2 permits during cautery
   • Avoid cautery near ETT cuff
   • Suction to remove smoke and prevent pooling

3. Emergency Preparedness:

   • 500 mL sterile saline immediately available
   • Fire drill protocol activated
   • Roles assigned (who disconnects, who removes ETT, who floods airway)

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SAQ 2: Post-Airway Fire Management

Question: (20 marks) An airway fire occurred during laser laryngeal surgery. The fire has been extinguished and the patient has been re-intubated.

a) Describe your immediate post-fire assessment. (8 marks)

b) What investigations are indicated? (4 marks)

c) Outline the subsequent management plan for the first 24 hours. (8 marks)

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Model Answer:

a) Immediate Post-Fire Assessment (8 marks):

1. Airway Assessment (3 marks):

   • Visual inspection via laryngoscopy: oedema, burns, debris
   • Check ETT position and security (may need smaller tube)
   • Assess vocal cord movement if feasible
   • Look for signs of thermal injury (charring, sloughing)

2. Breathing Assessment (2 marks):

   • Auscultation for wheeze, asymmetry
   • SpO2 monitoring on 100% O2
   • EtCO2 waveform analysis
   • Respiratory rate and pattern

3. Circulation/Neurological (2 marks):

   • HR, BP for signs of stress response or hypovolaemia
   • GCS assessment (exclude hypoxic injury)
   • Pupil examination (hypoxic brain injury)

4. Fire Debris Assessment (1 mark):

   • Suction oropharynx for ETT fragments
   • Document findings

b) Investigations (4 marks):

1. Mandatory (2 marks):

   • Fibreoptic bronchoscopy: assess tracheobronchial tree for burns, debris, strictures
   • Chest X-ray: exclude pneumothorax, look for thermal injury signs

2. As Indicated (2 marks):

   • ABG with COHb (carboxyhaemoglobin) if smoke inhalation suspected
   • CT chest if tracheal perforation suspected
   • Laryngoscopy by ENT surgeon for detailed assessment
   • Spirometry once recovered (baseline lung function)

c) 24-Hour Management Plan (8 marks):

1. Airway Management (3 marks):

   • Secure airway with cuffed ETT
   • Humidified oxygen (heated humidification)
   • Elevation of head to 30° (reduce airway oedema)
   • Steroids: Dexamethasone 8mg IV q8h (reduce oedema)

2. Monitoring (2 marks):

   • ICU or HDU admission (Grade 2-4 fires)
   • Continuous SpO2 monitoring
   • Peak airway oedema at 12-24 hours - highest risk period
   • Hourly respiratory rate, auscultation

3. Respiratory Support (2 marks):

   • Bronchodilators if bronchospasm (salbutamol)
   • Nebulised adrenaline if significant supraglottic oedema
   • Protective lung ventilation (TV 6-8 mL/kg, plateau <30)
   • PEEP 5-10 cmH₂O

4. Follow-up (1 mark):

   • Repeat bronchoscopy at 24-48 hours
   • Speech therapy referral if vocal cord injury
   • Psychological support for patient
   • Incident reporting and root cause analysis

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SAQ 3: Bowel Surgery Fire Prevention

Question: (15 marks) You are anaesthetising a patient for laparoscopic right hemicolectomy.

a) Explain why bowel surgery presents fire risk. (5 marks)

b) What specific measures do you take to prevent fire during this procedure? (10 marks)

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Model Answer:

a) Bowel Surgery Fire Risk (5 marks):

1. Fuel Sources (3 marks):

   • Intraluminal bowel gas: 50-60% nitrogen, 20-30% carbon dioxide, 7-10% methane, 2-4% hydrogen, trace hydrogen sulfide
   • Methane: Flammable (flammable range 5-15% in air)
   • Hydrogen: Highly flammable (flammable range 4-75%)
   • Peritoneal gas from insufflation can contain escaped bowel gas

2. Ignition Sources (1 mark):

   • Electrocautery (monopolar/bipolar)
   • Harmonic scalpel/ultrasonic devices
   • Heated irrigation solutions
   • Laser (rare in bowel surgery)

3. Oxidiser (1 mark):

   • Oxygen from pneumoperitoneum leakage
   • Nitrous oxide diffuses into bowel lumen (concentration builds up)

b) Fire Prevention Measures (10 marks):

1. Anaesthetic Gas Management (4 marks):

   • Avoid nitrous oxide: Diffuses into bowel lumen, increases gas volume, supports combustion
   • Use air/oxygen mixture or total intravenous anaesthesia
   • Maintain FiO2 at lowest safe level (21-30%)
   • Ensure adequate muscle relaxation (prevents straining)

2. Surgical Coordination (3 marks):

   • Pre-operative bowel preparation (reduces intraluminal gas volume)
   • Suction bowel gas before anastomosis
   • Surgeon to "vent" bowel before cautery use near bowel
   • Minimise use of cautery near unprotected bowel

3. Pneumoperitoneum Management (2 marks):

   • Use CO2 for insufflation (not air/N₂O)
   • Maintain adequate but not excessive pressure (12-15 mmHg typical)
   • Regular desufflation to release accumulated gas

4. Preparation and Monitoring (1 mark):

   • Fire risk assessment documented
   • Saline available for dousing if fire occurs
   • Team briefing on fire protocol
   • Check cautery grounding pad

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